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Sample records for tio2 solar cell

  1. Doping of TiO2 for sensitized solar cells.

    PubMed

    Roose, Bart; Pathak, Sandeep; Steiner, Ullrich

    2015-11-21

    This review gives a detailed summary and evaluation of the use of TiO2 doping to improve the performance of dye sensitized solar cells. Doping has a major effect on the band structure and trap states of TiO2, which in turn affect important properties such as the conduction band energy, charge transport, recombination and collection. The defect states of TiO2 are highly dependent on the synthesis method and thus the effect of doping may vary for different synthesis techniques, making it difficult to compare the suitability of different dopants. High-throughput methods may be employed to achieve a rough prediction on the suitability of dopants for a specific synthesis method. It was however found that nearly every employed dopant can be used to increase device performance, indicating that the improvement is not so much caused by the dopant itself, as by the defects it eliminates from TiO2. Furthermore, with the field shifting from dye sensitized solar cells to perovskite solar cells, the role doping can play to further advance this emerging field is also discussed.

  2. Effect of TiO2 blocking layer on TiO2 nanorod arrays based dye sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Sivakumar, R.; Paulraj, M.

    2016-05-01

    Highly ordered rutile titanium dioxide nanorod (TNR) arrays (1.2 to 6.2 μm thickness) were grown on TiO2 blocking layer chemically deposited on fluorine doped tin oxide (FTO) substrate and were used as photo-electrodes to fabricate dye sensitized solar cells (DSSC's). Homogeneous layer of TiO2 on FTO was achieved by using aqueous peroxo- titanium complex (PTC) solutions via chemical bath deposition. Structural and morphological properties of the prepared samples were investigated using X-ray diffraction (XRD), scanning electron microscopy (SEM) measurements. TNR arrays (6.2 μm) with TiO2 blocking layer showed higher energy conversion efficiency (1.46%) than that without TiO2 blocking layer. The reason can be ascertained to the suppression of electron-hole recombination at the semiconductor/electrolyte interface by the effect of TiO2 blocking layer.

  3. Enhanced performance of natural dye sensitised solar cells fabricated using rutile TIO2 nanorods

    NASA Astrophysics Data System (ADS)

    Akila, Y.; Muthukumarasamy, N.; Agilan, S.; Mallick, Tapas K.; Senthilarasu, S.; Velauthapillai, Dhayalan

    2016-08-01

    Due to the lower cost, natural dye molecules are good alternatives for the ruthenium based sensitizers in the dye-sensitized solar cells. In this article, we have reported the natural sensitizer based dye-sensitized solar cells fabricated using TiO2 nanorods. Rutile phase TiO2 nanorods have been synthesized by template free hydrothermal method which results in TiO2 nanorods in the form of acropora corals. These TiO2 nanorods have been sensitized by flowers of Sesbania grandiflora, leaves of Camellia sinensis and roots of Rubia tinctorum. The maximum conversion efficiency of 1.53% has been obtained for TiO2 nanorods based solar cells sensitized with the leaves of Camellia sinensis. The flowers of Sesbania grandiflora and roots of Rubia tinctorum sensitized TiO2 nanorods based solar cells exhibited an efficiency of 0.65% and 1.28% respectively.

  4. Mesoporous submicrometer TiO(2) hollow spheres as scatterers in dye-sensitized solar cells.

    PubMed

    Dadgostar, Shabnam; Tajabadi, Fariba; Taghavinia, Nima

    2012-06-27

    Hierarchical submicrometer TiO2 hollow spheres with outer diameter of 300-700 nm and shell thickness of 200 nm are synthesized by liquid phase deposition of TiO2 over carbon microspheres as sacrificial templates. The final TiO2 hollow spheres are applied as a scattering layer on top of a transparent nanocrystalline TiO2 film, serving as the photoanode of a dye-sensitized solar cell (DSC). In addition to efficient light scattering, the mesoporous structure of TiO2 hollow spheres provides a high surface area, 74 m(2)/g, which allows for higher dye loading. This dual functioning suggests that TiO2 hollow spheres may be good replacements for conventional TiO2 spheres as scatterers in DSCs. A high efficiency of 8.3% is achieved with TiO2 hollow spheres, compared with 6.0% for the electrode with 400 nm spherical TiO2 scatterers, at identical conditions. PMID:22606936

  5. Inverted polymer solar cells with employing of electrochemical-anodizing synthesized TiO2 nanotubes

    NASA Astrophysics Data System (ADS)

    Mehdi, Ahmadi; Sajjad Rashidi, Dafeh; Hamed, Fatehy

    2016-04-01

    An inverted structure of polymer solar cells based on Poly(3-hexylthiophene)(P3HT):[6-6] Phenyl-(6) butyric acid methyl ester (PCBM) with using thin films of TiO2 nanotubes and nanoparticles as an efficient cathode buffer layer is developed. A total of three cells employing TiO2 thin films with different thickness values are fabricated. Two cells use layers of TiO2 nanotubes prepared via self-organized electrochemical-anodizing leading to thickness values of 203 and 423.7 nm, while the other cell uses only a simple sol-gel synthesized TiO2 thin film of nanoparticles with a thickness of 100 nm as electron transport layer. Experimental results demonstrate that TiO2 nanotubes with these thickness values are inefficient as the power conversion efficiency of the cell using 100-nm TiO2 thin film is 1.55%, which is more than the best power conversion efficiency of other cells. This can be a result of the weakness of the electrochemical anodizing method to grow nanotubes with lower thickness values. In fact as the TiO2 nanotubes grow in length the series resistance (R s) between the active polymer layer and electron transport layer increases, meanwhile the fill factor of cells falls dramatically which finally downgrades the power conversion efficiency of the cells as the fill factor falls.

  6. Efficient Perovskite Solar Cells Depending on TiO2 Nanorod Arrays.

    PubMed

    Li, Xin; Dai, Si-Min; Zhu, Pei; Deng, Lin-Long; Xie, Su-Yuan; Cui, Qian; Chen, Hong; Wang, Ning; Lin, Hong

    2016-08-24

    Perovskite solar cells (PSCs) with TiO2 materials have attracted much attention due to their high photovoltaic performance. Aligned TiO2 nanorods have long been used for potential application in highly efficient perovskite solar cells, but the previously reported efficiencies of perovskite solar cells based on TiO2 nanorod arrays were underrated. Here we show a solvothermal method based on a modified ketone-HCl system with the addition of organic acids suitable for modulation of the TiO2 nanorod array films to fabricate highly efficient perovskite solar cells. Photovoltaic measurements indicated that efficient nanorod-structured perovskite solar cells can be achieved with the length of the nanorods as long as approximately 200 nm. A record efficiency of 18.22% under the reverse scan direction has been optimized by avoiding direct contact between the TiO2 nanorods and the hole transport materials, eliminating the organic residues on the nanorod surfaces using UV-ozone treatment and tuning the nanorod array morphologies through addition of different organic acids in the solvothermal process. PMID:27480286

  7. Efficient Perovskite Solar Cells Depending on TiO2 Nanorod Arrays.

    PubMed

    Li, Xin; Dai, Si-Min; Zhu, Pei; Deng, Lin-Long; Xie, Su-Yuan; Cui, Qian; Chen, Hong; Wang, Ning; Lin, Hong

    2016-08-24

    Perovskite solar cells (PSCs) with TiO2 materials have attracted much attention due to their high photovoltaic performance. Aligned TiO2 nanorods have long been used for potential application in highly efficient perovskite solar cells, but the previously reported efficiencies of perovskite solar cells based on TiO2 nanorod arrays were underrated. Here we show a solvothermal method based on a modified ketone-HCl system with the addition of organic acids suitable for modulation of the TiO2 nanorod array films to fabricate highly efficient perovskite solar cells. Photovoltaic measurements indicated that efficient nanorod-structured perovskite solar cells can be achieved with the length of the nanorods as long as approximately 200 nm. A record efficiency of 18.22% under the reverse scan direction has been optimized by avoiding direct contact between the TiO2 nanorods and the hole transport materials, eliminating the organic residues on the nanorod surfaces using UV-ozone treatment and tuning the nanorod array morphologies through addition of different organic acids in the solvothermal process.

  8. TiO2 Sub-microsphere Film as Scaffold Layer for Efficient Perovskite Solar Cells.

    PubMed

    Huang, Yang; Zhu, Jun; Ding, Yong; Chen, Shuanghong; Zhang, Changneng; Dai, Songyuan

    2016-03-01

    TiO2 sub-microspheres composed of anatase granular-like nanocrystallines with an average diameter ∼250 nm are synthesized using sol-gel method and employed as the scaffold layer for efficient mesocopic perovskite solar cells. Compared with mesoporous TiO2 films composed of ∼18 nm nanoparticles, the sub-microsphere films show superior light-trapping characteristics and significantly improve the light-harvesting capability of the solar cells. In addition, the charge-transport performance is also dramatically improved according to the transient photocurrent decay despite there being no significant difference in the perovskite layer surface morphology. As a result, an average power conversion efficiency of 15% with a highly uniform distribution is achieved for the solar cells with TiO2 sub-microsphere films, 12% higher than those with TiO2 nanoparticle films. The combination of light-harvesting capability and fast charge transfer make the TiO2 sub-microsphere film a good candidate as the scaffold layer for efficient perovskite solar cells. PMID:26953635

  9. TiO2 Sub-microsphere Film as Scaffold Layer for Efficient Perovskite Solar Cells.

    PubMed

    Huang, Yang; Zhu, Jun; Ding, Yong; Chen, Shuanghong; Zhang, Changneng; Dai, Songyuan

    2016-03-01

    TiO2 sub-microspheres composed of anatase granular-like nanocrystallines with an average diameter ∼250 nm are synthesized using sol-gel method and employed as the scaffold layer for efficient mesocopic perovskite solar cells. Compared with mesoporous TiO2 films composed of ∼18 nm nanoparticles, the sub-microsphere films show superior light-trapping characteristics and significantly improve the light-harvesting capability of the solar cells. In addition, the charge-transport performance is also dramatically improved according to the transient photocurrent decay despite there being no significant difference in the perovskite layer surface morphology. As a result, an average power conversion efficiency of 15% with a highly uniform distribution is achieved for the solar cells with TiO2 sub-microsphere films, 12% higher than those with TiO2 nanoparticle films. The combination of light-harvesting capability and fast charge transfer make the TiO2 sub-microsphere film a good candidate as the scaffold layer for efficient perovskite solar cells.

  10. Microwave-assisted synthesis of nanocrystalline TiO2 for dye-sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Kuo, Ta-Chuan; Guo, Tzung-Fang; Chen, Peter

    2012-09-01

    The main purposes of this study are replacing conventional hydro-thermal method by microwave heating using water as reaction medium to rapidly synthesize TiO2.Titanium tetraisopropoxide (TTIP) was hydrolyzed in water. The solution is subsequently processed with microwave heating for crystal growth. The reaction time could be shortened into few minutes. Then we chose different acids as dispersion agents to prepare TiO2 paste for investigating the effects of dispersion on the power conversion efficiency of dye-sensitized solar cells (DSCs). The photovoltaic performance of the microwave-assisted synthesized TiO2 achieved power conversion efficiency of 6.31% under AM 1.5 G condition (100 mW/cm2). This PCE value is compatible with that of the devices made from commercial TiO2.

  11. Research Update: Doping ZnO and TiO2 for solar cells

    NASA Astrophysics Data System (ADS)

    Hoye, Robert L. Z.; Musselman, Kevin P.; MacManus-Driscoll, Judith L.

    2013-12-01

    ZnO and TiO2 are two of the most commonly used n-type metal oxide semiconductors in new generation solar cells due to their abundance, low-cost, and stability. ZnO and TiO2 can be used as active layers, photoanodes, buffer layers, transparent conducting oxides, hole-blocking layers, and intermediate layers. Doping is essential to tailor the materials properties for each application. The dopants used and their impact in solar cells are reviewed. In addition, the advantages, disadvantages, and commercial potential of the various fabrication methods of these oxides are presented.

  12. Eco-friendly synthesis of TiO2, Au and Pt doped TiO2 nanoparticles for dye sensitized solar cell applications and evaluation of toxicity

    NASA Astrophysics Data System (ADS)

    Gopinath, K.; Kumaraguru, S.; Bhakyaraj, K.; Thirumal, S.; Arumugam, A.

    2016-04-01

    Driven by the demand of pure TiO2, Au and Pt doped TiO2 NPs were successfully synthesized using Terminalia arjuna bark extract. The eco-friendly synthesized NPs were characterized by UV-Vis-DRS, ATR-FT-IR, PL, XRD, Raman, SEM with EDX and TEM analysis. The synthesized NPs were investigation for dye sensitized solar cell applications. UV-Vis-Diffused Reflectance Spectra clearly showed that the expected TiO2 inter band absorption below 306 nm, incorporation of gold shows surface plasma resonant (SPR) near 555 nm and platinum incorporated TiO2 NPs shows absorbance at 460 nm. The energy conversion efficiency for Au doped TiO2 NPs when compared to pure and Pt doped TiO2 NPs. In addition to that, Au noble metal present TiO2 matrix and an improve open-circuit voltage (Voc) of DSSC. Synthesized NPs was evaluated into antibacterial and antifungal activities by disk diffusion method. It is observed that NPs have not shown any activities in all tested bacterial and fungal strains. In this eco-friendly synthesis method to provide non toxic and environmental friendly nanomaterials can be used for solar energy device application.

  13. Spherical TiO2 aggregates with different building units for dye-sensitized solar cells.

    PubMed

    Liu, Zhaohui; Su, Xunjia; Hou, Genliang; Bi, Song; Xiao, Zhou; Jia, Haipeng

    2013-09-01

    Tailoring the architectures of spherical TiO2 aggregates is crucial to obtain superior photovoltaic properties and promote their application in dye-sensitized solar cells (DSSCs). Herein, we synthesized spherical TiO2 aggregates using different building units, including nanocrystallites, nanorods, nanosheets, and nanotubes, via a hydrothermal method, and studied the effect of the building units on the performances of DSSCs. The aggregates assembled by uniform nanosheet and nanotube building units were synthesized with the use of spherical TiO2 nanorod aggregates as titanium sources in an alkaline hydrothermal reaction. Compared with TiO2 nanoparticles, the spherical TiO2 aggregates possess higher surface area, more efficient light scattering ability, and better electron transport properties. Among the four types of spherical TiO2 aggregates; the nanorod, nanotube, and nanosheet aggregates demonstrate better electron transport properties than the nanocrystallite aggregates; the nanotube and nanosheet aggregates exhibit more efficient light scattering than the nanocrystallite and nanorod aggregates; and the nanotube aggregates show the highest surface area. Thus the DSSC based on nanotube aggregates exhibited the highest energy conversion efficiency of 7.48%, which is 16.0%, 9.7%, and 19.5% higher than those of the DSSCs based on the nanosheet, nanorod, and nanocrystallite aggregates, respectively.

  14. Plasmonic Effect in Au-Added TiO2-Based Solar Cell

    NASA Astrophysics Data System (ADS)

    Van Hong, Le; Cat, Do Tran; Chi, Le Ha; Thuy, Nguyen Thi; Van Hung, Tran; Tai, Ly Ngoc; Long, Pham Duy

    2016-06-01

    TiO2 nano thin films have been fabricated on fluoride tin oxide (FTO) film electrodes by hydrothermal synthesis at temperatures of 80°C, 120°C, 150°C, and 200°C for different synthesis times of 1 h, 2 h, and 3 h in 2.5 mol, 5 mol, and 7.5 mol NaOH solution. X-ray diffraction patterns and field-emission scanning electron microscopy (FESEM) images were recorded for all the film samples, and the results confirmed that TiO2 anatase phase was generally formed in nanowire form. The influence of synthesis temperature, processing time, and NaOH content on the structure and morphology of the TiO2 material was studied. Au nanoparticles with size of around 2 × 10-8 m were added into the TiO2 thin films by thermal evaporation in vacuum combined with thermal annealing. Based on photocurrent-voltage (I-V) characteristics measured under irradiation with visible light, the short-circuit current, open-circuit voltage, and efficiency of solar cells with FTO/Au-added TiO2/(I-/I2-) electrolyte/Pt configuration were evaluated. The short-circuit current and efficiency of the Au-added solar cell were greatly improved, which is supposed to be related to a contribution of the surface plasmon resonance effect.

  15. Microstructure design of nanoporous TiO2 photoelectrodes for dye-sensitized solar cell modules.

    PubMed

    Hu, Linhua; Dai, Songyuan; Weng, Jian; Xiao, Shangfeng; Sui, Yifeng; Huang, Yang; Chen, Shuanghong; Kong, Fantai; Pan, Xu; Liang, Linyun; Wang, Kongjia

    2007-01-18

    The optimization of dye-sensitized solar cells, especially the design of nanoporous TiO2 film microstructure, is an urgent problem for high efficiency and future commercial applications. However, up to now, little attention has been focused on the design of nanoporous TiO2 microstructure for a high efficiency of dye-sensitized solar cell modules. The optimization and design of TiO2 photoelectrode microstructure are discussed in this paper. TiO2 photoelectrodes with three different layers, including layers of small pore size films, larger pore size films, and light-scattering particles on the conducting glass with the desirable thickness, were designed and investigated. Moreover, the photovoltaic properties showed that the different porosities, pore size distribution, and BET surface area of each layer have a dramatic influence on short-circuit current, open-circuit voltage, and fill factor of the modules. The optimization and design of TiO2 photoelectrode microstructure contribute a high efficiency of DSC modules. The photoelectric conversion efficiency around 6% with 15 x 20 cm2 modules under illumination of simulated AM1.5 sunlight (100 mW/cm2) and 40 x 60 cm2 panels with the same performance tested outdoor have been achieved by our group.

  16. Plasmonic Effect in Au-Added TiO2-Based Solar Cell

    NASA Astrophysics Data System (ADS)

    Van Hong, Le; Cat, Do Tran; Chi, Le Ha; Thuy, Nguyen Thi; Van Hung, Tran; Tai, Ly Ngoc; Long, Pham Duy

    2016-10-01

    TiO2 nano thin films have been fabricated on fluoride tin oxide (FTO) film electrodes by hydrothermal synthesis at temperatures of 80°C, 120°C, 150°C, and 200°C for different synthesis times of 1 h, 2 h, and 3 h in 2.5 mol, 5 mol, and 7.5 mol NaOH solution. X-ray diffraction patterns and field-emission scanning electron microscopy (FESEM) images were recorded for all the film samples, and the results confirmed that TiO2 anatase phase was generally formed in nanowire form. The influence of synthesis temperature, processing time, and NaOH content on the structure and morphology of the TiO2 material was studied. Au nanoparticles with size of around 2 × 10-8 m were added into the TiO2 thin films by thermal evaporation in vacuum combined with thermal annealing. Based on photocurrent-voltage ( I- V) characteristics measured under irradiation with visible light, the short-circuit current, open-circuit voltage, and efficiency of solar cells with FTO/Au-added TiO2/(I-/I2-) electrolyte/Pt configuration were evaluated. The short-circuit current and efficiency of the Au-added solar cell were greatly improved, which is supposed to be related to a contribution of the surface plasmon resonance effect.

  17. Low crystallinity TiO2 film with inherent low oxygen vacancy for sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Tang, Xiao; Liu, Xiaoyan; Zhang, Ling; Xing, Yali; Tian, Yi

    2014-09-01

    Instead of perfect crystallization or surface defect-removing treatments, this study suggests an alternative route of oxygen vacancy reduction, i.e. amorphization, to improve the electron transport properties of TiO2 mesoporous films. In this paper, a low crystallinity TiO2 mesoporous film with inherent low content of oxygen vacancies is used as the photoanode of dye-sensitized solar cells (DSCs). Electrochemical impedance spectroscopy (EIS) analysis indicates the high electron diffusion coefficient and long electron life time of the low crystallinity TiO2 photoanode. An extraordinary high open photovoltage of 860 mV is achieved owing to the low oxygen vacancy. And also the charge recombination of the internal cell significantly decreases, thus enhances the utilization efficiency of dye, which has been characterized with the high ratio of short circuit photocurrent to dye-loading.

  18. Electrodeposited Ultrathin TiO2 Blocking Layers for Efficient Perovskite Solar Cells

    PubMed Central

    Su, Tzu-Sen; Hsieh, Tsung-Yu; Hong, Cheng-You; Wei, Tzu-Chien

    2015-01-01

    In this study, the electrodeposition (ED) of ultrathin, compact TiO2 blocking layers (BLs) on fluorine-doped tin oxide (FTO) glass for perovskite solar cells (PSCs) is evaluated. This bottom-up method allows for controlling the morphology and thickness of TiO2 films by simply manipulating deposition conditions. Compared with BLs produced using the spin-coating (SC) method, BLs produced using ED exhibit satisfactory surface coverage, even with a film thickness of 29 nm. Evidence from cyclic voltammetry shows that an ED BL suppresses interfacial recombination more profoundly than an SC BL does, consequently improving the photovoltaic properties of the PSC significantly. A PSC equipped with an ED TiO2 BL having a 13.6% power conversion efficiency is demonstrated. PMID:26526771

  19. Electrodeposited Ultrathin TiO2 Blocking Layers for Efficient Perovskite Solar Cells

    NASA Astrophysics Data System (ADS)

    Su, Tzu-Sen; Hsieh, Tsung-Yu; Hong, Cheng-You; Wei, Tzu-Chien

    2015-11-01

    In this study, the electrodeposition (ED) of ultrathin, compact TiO2 blocking layers (BLs) on fluorine-doped tin oxide (FTO) glass for perovskite solar cells (PSCs) is evaluated. This bottom-up method allows for controlling the morphology and thickness of TiO2 films by simply manipulating deposition conditions. Compared with BLs produced using the spin-coating (SC) method, BLs produced using ED exhibit satisfactory surface coverage, even with a film thickness of 29 nm. Evidence from cyclic voltammetry shows that an ED BL suppresses interfacial recombination more profoundly than an SC BL does, consequently improving the photovoltaic properties of the PSC significantly. A PSC equipped with an ED TiO2 BL having a 13.6% power conversion efficiency is demonstrated.

  20. TiO2-Coated Carbon Nanotube-Silicon Solar Cells with Efficiency of 15%

    NASA Astrophysics Data System (ADS)

    Shi, Enzheng; Zhang, Luhui; Li, Zhen; Li, Peixu; Shang, Yuanyuan; Jia, Yi; Wei, Jinquan; Wang, Kunlin; Zhu, Hongwei; Wu, Dehai; Zhang, Sen; Cao, Anyuan

    2012-11-01

    Combining carbon nanotubes (CNTs), graphene or conducting polymers with conventional silicon wafers leads to promising solar cell architectures with rapidly improved power conversion efficiency until recently. Here, we report CNT-Si junction solar cells with efficiencies reaching 15% by coating a TiO2 antireflection layer and doping CNTs with oxidative chemicals, under air mass (AM 1.5) illumination at a calibrated intensity of 100 mW/cm2 and an active device area of 15 mm2. The TiO2 layer significantly inhibits light reflectance from the Si surface, resulting in much enhanced short-circuit current (by 30%) and external quantum efficiency. Our method is simple, well-controlled, and very effective in boosting the performance of CNT-Si solar cells.

  1. TiO2 hierarchical nanostructures: Hydrothermal fabrication and application in dye-sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Liang, Jia; Zhang, Gengmin; Yang, Jin; Sun, Wentao; Shi, Mingji

    2015-01-01

    Arrays of TiO2 hierarchical nanostructures that consisted of rutile nanorods and anatase branches were hydrothermally fabricated and employed as photoanodes in dye-sensitized solar cells (DSSCs). Each hierarchical nanostructure array was attained in two steps. First, a primary nanorod array was synthesized in aqueous solutions of hydrochloric acid (HCl) and tetrabutyl titanate (C16H36O4Ti); subsequently, secondary branches were grown on the nanorods in aqueous solutions of ammonium hexafluorotitanate ((NH4)2TiF6) and boric acid (H3BO3). The secondary anatase branches filled part of the space among the primary rutile nanorods and gave rise to a larger surface area. Light-harvesting capability of the DSSCs with TiO2 hierarchical nanostructures as photoanodes was appreciably improved because more dye molecules could be loaded on the photoanodes and more light could be scattered inside the DSSCs. Therefore, the conversion efficiencies of the DSSCs were doubled by replacing the photoanode of primary TiO2 nanorod array with the photoanodes of TiO2 hierarchical nanostructure arrays. Furthermore, in order to reach a compromise between the photoanode surface area and the inter-nanorod space volume, the growth time of the secondary TiO2 anatase branches was optimized.

  2. Vertically aligned nanostructured TiO2 photoelectrodes for high efficiency perovskite solar cells via a block copolymer template approach

    NASA Astrophysics Data System (ADS)

    Seo, Myung-Seok; Jeong, Inyoung; Park, Joon-Suh; Lee, Jinwoo; Han, Il Ki; Lee, Wan In; Son, Hae Jung; Sohn, Byeong-Hyeok; Ko, Min Jae

    2016-06-01

    We fabricated perovskite solar cells with enhanced device efficiency based on vertically oriented TiO2 nanostructures using a nanoporous template of block copolymers (BCPs). The dimension and shape controllability of the nanopores of the BCP template allowed for the construction of one-dimensional (1-D) TiO2 nanorods and two-dimensional (2-D) TiO2 nanowalls. The TiO2 nanorod-based perovskite solar cells showed a more efficient charge separation and a lower charge recombination, leading to better performance compared to TiO2 nanowall-based solar cells. The best solar cells employing 1-D TiO2 nanorods showed an efficiency of 15.5% with VOC = 1.02 V, JSC = 20.0 mA cm-2 and fill factor = 76.1%. Thus, TiO2 nanostructures fabricated from BCP nanotemplates could be applied to the preparation of electron transport layers for improving the efficiency of perovskite solar cells.We fabricated perovskite solar cells with enhanced device efficiency based on vertically oriented TiO2 nanostructures using a nanoporous template of block copolymers (BCPs). The dimension and shape controllability of the nanopores of the BCP template allowed for the construction of one-dimensional (1-D) TiO2 nanorods and two-dimensional (2-D) TiO2 nanowalls. The TiO2 nanorod-based perovskite solar cells showed a more efficient charge separation and a lower charge recombination, leading to better performance compared to TiO2 nanowall-based solar cells. The best solar cells employing 1-D TiO2 nanorods showed an efficiency of 15.5% with VOC = 1.02 V, JSC = 20.0 mA cm-2 and fill factor = 76.1%. Thus, TiO2 nanostructures fabricated from BCP nanotemplates could be applied to the preparation of electron transport layers for improving the efficiency of perovskite solar cells. Electronic supplementary information (ESI) available. See DOI: 10.1039/c6nr01010e

  3. Hydrothermal Etching Treatment to Rutile TiO2 Nanorod Arrays for Improving the Efficiency of CdS-Sensitized TiO2 Solar Cells.

    PubMed

    Wan, Jingshu; Liu, Rong; Tong, Yuzhu; Chen, Shuhuang; Hu, Yunxia; Wang, Baoyuan; Xu, Yang; Wang, Hao

    2016-12-01

    Highly ordered TiO2 nanorod arrays (NRAs) were directly grown on an F:SnO2 (FTO) substrate without any seed layer by hydrothermal route. For a larger surface area, the second-step hydrothermal treatment in hydrochloric acid was carried out to the as-prepared TiO2 NRAs. The results showed that the center portion of the TiO2 nanorods were dissolved in the etching solution to form a nanocave at the initial etching process. As the etching time extended, the tip parts of the nanocave wall split into lots of nanowires with a reduced diameter, giving rise to a remarkable increase of specific surface area for the TiO2 NRAs. The TiO2 films after etching treatment were sensitized by CdS quantum dots (QDs) to fabricate quantum dot-sensitized solar cells (QDSSCs), which exhibited a significant improvement in the photocurrent density in comparison with that of the un-treated device, this mainly attributed to the enhancement of QD loading and diffused reflectance ability. Through modifying the etching TiO2 films with TiCl4, a relatively high power conversion efficiency (PCE) of 3.14 % was obtained after optimizing the etching time.

  4. Hydrothermal Etching Treatment to Rutile TiO2 Nanorod Arrays for Improving the Efficiency of CdS-Sensitized TiO2 Solar Cells

    NASA Astrophysics Data System (ADS)

    Wan, Jingshu; Liu, Rong; Tong, Yuzhu; Chen, Shuhuang; Hu, Yunxia; Wang, Baoyuan; Xu, Yang; Wang, Hao

    2016-01-01

    Highly ordered TiO2 nanorod arrays (NRAs) were directly grown on an F:SnO2 (FTO) substrate without any seed layer by hydrothermal route. For a larger surface area, the second-step hydrothermal treatment in hydrochloric acid was carried out to the as-prepared TiO2 NRAs. The results showed that the center portion of the TiO2 nanorods were dissolved in the etching solution to form a nanocave at the initial etching process. As the etching time extended, the tip parts of the nanocave wall split into lots of nanowires with a reduced diameter, giving rise to a remarkable increase of specific surface area for the TiO2 NRAs. The TiO2 films after etching treatment were sensitized by CdS quantum dots (QDs) to fabricate quantum dot-sensitized solar cells (QDSSCs), which exhibited a significant improvement in the photocurrent density in comparison with that of the un-treated device, this mainly attributed to the enhancement of QD loading and diffused reflectance ability. Through modifying the etching TiO2 films with TiCl4, a relatively high power conversion efficiency (PCE) of 3.14 % was obtained after optimizing the etching time.

  5. An efficient photoanode consisting of TiO2 nanoparticle-filled TiO2 nanotube arrays for dye sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Zhang, Jun; Li, Quantong; Li, Siqian; Wang, Yi; Ye, Cong; Ruterana, Pierre; Wang, Hao

    2014-12-01

    An efficient photoanode consisting of TiO2 nanoparticle-filled TiO2 nanotube (TNT) arrays is prepared by a sol-gel process through hydrolysis and condensation of titaniumtetrachloride in an aqueous medium containing alcohol and ammonia. By introducing the TiO2 nanoparticles of proper particle size ∼20 nm into TNT arrays, the surface area, dye adsorption, short-circuit photocurrent density (Jsc), open circuit voltage (Voc) and the power conversion efficiency (PCE) of dye-sensitized solar cells (DSSCs) are significantly improved (up to 107% enhancement on PCE). Particularly, the addition of alcohol and ammonia in TiO2 sol results in more hydroxyl groups chemisorbed onto the surface of the photoanodes, which is favorable for achieving large amount of dye adsorption. The influence of sol-treating time on the microstructure, morphology of photoanodes and the corresponding photovoltaic performance of DSSCs are investigated. It is found that immersing the TNT arrays into TiO2 sol for 0.5-2 h gives PCE of DSSC higher than 9.6%, and the highest PCE of 9.86% is achieved in DSSC when treating the TNT arrays with TiO2 sol for 2 h.

  6. Improved performance of dye-sensitized solar cells using TiO2 nanotubes infiltrated by TiO2 nanoparticles using a dipping-rinsing-hydrolysis process

    NASA Astrophysics Data System (ADS)

    Lin, Lu-Yin; Chen, Chia-Yuan; Yeh, Min-Hsin; Tsai, Keng-Wei; Lee, Chuan-Pei; Vittal, R.; Wu, Chun-Guey; Ho, Kuo-Chuan

    2013-12-01

    An efficient back-illuminated dye-sensitized solar cell (DSSC) is made with a flexible Ti-foil based photoanode composed of a composite TiO2 film with TiO2 nanotubes (TNT) and TiO2 nanoparticles (TNP). The composite TiO2 film is fabricated through a novel dipping-rinsing-hydrolysis (DRH) process by inserting TiO2 into TNT and sintering the product to form TNP inside TNT. By directly placing TiO2 nanoparticles into TNT, the former grow internally from the base of TNT to occupy it completely. This solves previous problems of incomplete filling of TNP into TNT, which used partial penetration of TiCl4 reactant from the top of the TNT. In the present case, the TNP are grown from the base of TNT. A DSSC containing TNT and TNP prepared in this way shows a photoelectric efficiency of 6.45%, which is much higher than that (4.21%) of a DSSC with untreated TNT. The films are characterized by using scanning electron microscopy (SEM) and X-ray diffraction (XRD) analysis. The improvement in the photoelectric efficiency is explained by using electrochemical impedance spectroscopy (EIS), incident photon-to-current conversion efficiency (IPCE) analysis, and UV-absorption spectra analysis.

  7. Preparation of flexible TiO2 photoelectrodes for dye-sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Li, Wen-Ren; Wang, Hsiu-Hsuan; Lin, Chia-Feng; Su, Chaochin

    2014-09-01

    Dye-sensitized solar cells (DSSCs) based on nanocrystalline TiO2 photoelectrodes on indium tin oxide (ITO) coated polymer substrates have drawn great attention due to its lightweight, flexibility and advantages in commercial applications. However, the thermal instability of polymer substrates limits the process temperature to below 150 °C. In order to assure high and firm interparticle connection between TiO2 nanocrystals (TiO2-NC) and polymer substrates, the post-treatment of flexible TiO2 photoelectrodes (F-TiO2-PE) by mechanical compression was employed. In this work, Degussa P25 TiO2-NC was mixed with tert-butyl alcohol and DI-water to form TiO2 paste. F-TiO2-PE was then prepared by coating the TiO2 paste onto ITO coated polyethylene terephthalate (PET) substrate using doctor blade followed by low temperature sintering at 120 °C for 2 hours. To study the effect of mechanical compression, we applied 50 and 100 kg/cm2 pressure on TiO2/PET to complete the fabrication of F-TiO2-PE. The surface morphology of F-TiO2-PE was characterized using scanning electron microscopy. The resultant F-TiO2-PE sample exhibited a smooth, crack-free structure indicating the great improvement in the interparticle connection of TiO2-NC. Increase of compression pressure could lead to the increase of DSSC photoconversion efficiency. The best photoconversion efficiency of 4.19 % (open circuit voltage (Voc) = 0.79 V, short-circuit photocurrent density (Jsc) = 7.75 mA/cm2, fill factor (FF) = 0.68) was obtained for the F-TiO2-PE device, which showed great enhancement compared with the F-TiO2-PE cell without compression treatment. The effect of compression in DSSC performance was vindicated by the electrochemical impedance spectroscopy measurement.

  8. Influence of TiO2 Nanorod Arrays on the Bilayered Photoanode for Dye-Sensitized Solar Cells

    NASA Astrophysics Data System (ADS)

    Cao, Ya; Li, Zhen; Wang, Yang; Zhang, Tao; Li, Yinchang; Liu, Xueqin; Li, Fei

    2016-10-01

    A TiO2 bilayered structure consisting of TiO2 nanoparticles (TiO2NP) as an overlayer and single-crystal rutile TiO2 nanorods (TiO2 NRs) as an underlayer on a transparent conductive fluorine-doped tin oxide substrate was designed as the photoanode of dye-sensitized solar cells (DSSCs) through a facile hydrothermal treatment followed by a doctor-blade method. DSSCs based on the hierarchical TiO2 nano-architecture photoelectrode shows a power conversion efficiency of 7.39% because the relatively large specific surface area of TiO2NP increased the dye absorption, and oriented one-dimensional TiO2 NRs enhanced the light harvesting capability, accelerating interfacial electron transport. In particular, we observed the growth morphology of the TiO2 nanorod arrays in the bilayered photoanode and the influence of the whole solar cell. The result indicated that the TiO2 NRs layer clearly impacted the photoelectron chemical properties, while the vertical and intensive nanorod arrays significantly increased their performance.

  9. Yttrium-substituted nanocrystalline TiO2 photoanodes for perovskite based heterojunction solar cells

    NASA Astrophysics Data System (ADS)

    Qin, Peng; Domanski, Anna L.; Chandiran, Aravind Kumar; Berger, Rüdiger; Butt, Hans-Jürgen; Dar, M. Ibrahim; Moehl, Thomas; Tetreault, Nicolas; Gao, Peng; Ahmad, Shahzada; Nazeeruddin, Mohammad K.; Grätzel, Michael

    2014-01-01

    We report the use of Y3+-substituted TiO2 (0.5%Y-TiO2) in solid-state mesoscopic solar cells, consisting of CH3NH3PbI3 as the light harvester and spiro-OMeTAD as the hole transport material. A power conversion efficiency of 11.2% under simulated AM 1.5 full sun illumination was measured. A 15% improvement in the short-circuit current density was obtained compared with pure TiO2, due to the effect of Y3+ on the dimensions of perovskite nanoparticles formed on the semiconductor surface, showing that the surface modification of the semiconductor is an effective way to improve the light harvesters' morphology and electron transfer properties in the solid-state mesoscopic solar cells.We report the use of Y3+-substituted TiO2 (0.5%Y-TiO2) in solid-state mesoscopic solar cells, consisting of CH3NH3PbI3 as the light harvester and spiro-OMeTAD as the hole transport material. A power conversion efficiency of 11.2% under simulated AM 1.5 full sun illumination was measured. A 15% improvement in the short-circuit current density was obtained compared with pure TiO2, due to the effect of Y3+ on the dimensions of perovskite nanoparticles formed on the semiconductor surface, showing that the surface modification of the semiconductor is an effective way to improve the light harvesters' morphology and electron transfer properties in the solid-state mesoscopic solar cells. Electronic supplementary information (ESI) available: Paste preparation; the HRTEM micrograph of dark coloured individual nanoparticles deposited on TiO2; histogram plots of solar cell performance parameters for 15 cells based on TiO2; the Nyquist plot of the device without Y at 500 mV forward bias. See DOI: 10.1039/c3nr05884k

  10. Anatase TiO(2) nanosheets with exposed (001) facets: improved photoelectric conversion efficiency in dye-sensitized solar cells.

    PubMed

    Yu, Jiaguo; Fan, Jiajie; Lv, Kangle

    2010-10-01

    Dye-sensitized solar cells (DSSCs) are fabricated based on anatase TiO(2) nanosheets (TiO(2)-NSs) with exposed {001} facets, which were obtained by a simple one-pot hydrothermal route using HF as a morphology controlling agent and Ti(OC(4)H(9))(4) as precursor. The prepared samples were characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, UV-vis absorption spectroscopy and N(2) adsorption-desorption isotherms. The photoelectric conversion performances of TiO(2)-NSs solar cells are also compared with TiO(2) nanoparticles (TiO(2)-NPs) and commercial-grade Degussa P25 TiO(2) nanoparticle (P25) solar cells at the same film thickness, and their photoelectric conversion efficiencies (η) are 4.56, 4.24 and 3.64%, respectively. The enhanced performance of the TiO(2)-NS solar cell is due to their good crystallization, high pore volume, large particle size and enhanced light scattering. The prepared TiO(2) nanosheet film electrode should also find wide-ranging potential applications in various fields including photocatalysis, catalysis, electrochemistry, separation, purification and so on.

  11. Anatase TiO2 nanosheets with exposed (001) facets: improved photoelectric conversion efficiency in dye-sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Yu, Jiaguo; Fan, Jiajie; Lv, Kangle

    2010-10-01

    Dye-sensitized solar cells (DSSCs) are fabricated based on anatase TiO2 nanosheets (TiO2-NSs) with exposed {001} facets, which were obtained by a simple one-pot hydrothermal route using HF as a morphology controlling agent and Ti(OC4H9)4 as precursor. The prepared samples were characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, UV-vis absorption spectroscopy and N2 adsorption-desorption isotherms. The photoelectric conversion performances of TiO2-NSs solar cells are also compared with TiO2 nanoparticles (TiO2-NPs) and commercial-grade Degussa P25 TiO2 nanoparticle (P25) solar cells at the same film thickness, and their photoelectric conversion efficiencies (η) are 4.56, 4.24 and 3.64%, respectively. The enhanced performance of the TiO2-NS solar cell is due to their good crystallization, high pore volume, large particle size and enhanced light scattering. The prepared TiO2 nanosheet film electrode should also find wide-ranging potential applications in various fields including photocatalysis, catalysis, electrochemistry, separation, purification and so on.

  12. Wire-shaped perovskite solar cell based on TiO2 nanotubes

    NASA Astrophysics Data System (ADS)

    Wang, Xiaoyan; Kulkarni, Sneha A.; Li, Zhen; Xu, Wenjing; Batabyal, Sudip K.; Zhang, Sam; Cao, Anyuan; Wong, Lydia Helena

    2016-05-01

    In this work, a wire-shaped perovskite solar cell based on TiO2 nanotube (TNT) arrays is demonstrated for the first time by integrating a perovskite absorber on TNT-coated Ti wire. Anodization was adopted for the conformal growth of TNTs on Ti wire, together with the simultaneous formation of a compact TiO2 layer. A sequential step dipping process is employed to produce a uniform and compact perovskite layer on top of TNTs with conformal coverage as the efficient light absorber. Transparent carbon nanotube film is wrapped around Ti wire as the hole collector and counter electrode. The integrated perovskite solar cell wire by facile fabrication approaches shows a promising future in portable and wearable textile electronics.

  13. Wire-shaped perovskite solar cell based on TiO2 nanotubes.

    PubMed

    Wang, Xiaoyan; Kulkarni, Sneha A; Li, Zhen; Xu, Wenjing; Batabyal, Sudip K; Zhang, Sam; Cao, Anyuan; Wong, Lydia Helena

    2016-05-20

    In this work, a wire-shaped perovskite solar cell based on TiO2 nanotube (TNT) arrays is demonstrated for the first time by integrating a perovskite absorber on TNT-coated Ti wire. Anodization was adopted for the conformal growth of TNTs on Ti wire, together with the simultaneous formation of a compact TiO2 layer. A sequential step dipping process is employed to produce a uniform and compact perovskite layer on top of TNTs with conformal coverage as the efficient light absorber. Transparent carbon nanotube film is wrapped around Ti wire as the hole collector and counter electrode. The integrated perovskite solar cell wire by facile fabrication approaches shows a promising future in portable and wearable textile electronics.

  14. Reduced Graphene Oxide/Mesoporous TiO2 Nanocomposite Based Perovskite Solar Cells.

    PubMed

    Han, Gill Sang; Song, Young Hyun; Jin, Young Un; Lee, Jin-Wook; Park, Nam-Gyu; Kang, Bong Kyun; Lee, Jung-Kun; Cho, In Sun; Yoon, Dae Ho; Jung, Hyun Suk

    2015-10-28

    We report on reduced graphene oxide (rGO)/mesoporous (mp)-TiO2 nanocomposite based mesostructured perovskite solar cells that show an improved electron transport property owing to the reduced interfacial resistance. The amount of rGO added to the TiO2 nanoparticles electron transport layer was optimized, and their impacts on film resistivity, electron diffusion, recombination time, and photovoltaic performance were investigated. The rGO/mp-TiO2 nanocomposite film reduces interfacial resistance when compared to the mp-TiO2 film, and hence, it improves charge collection efficiency. This effect significantly increases the short circuit current density and open circuit voltage. The rGO/mp-TiO2 nanocomposite film with an optimal rGO content of 0.4 vol % shows 18% higher photon conversion efficiency compared with the TiO2 nanoparticles based perovskite solar cells.

  15. Wire-shaped perovskite solar cell based on TiO2 nanotubes.

    PubMed

    Wang, Xiaoyan; Kulkarni, Sneha A; Li, Zhen; Xu, Wenjing; Batabyal, Sudip K; Zhang, Sam; Cao, Anyuan; Wong, Lydia Helena

    2016-05-20

    In this work, a wire-shaped perovskite solar cell based on TiO2 nanotube (TNT) arrays is demonstrated for the first time by integrating a perovskite absorber on TNT-coated Ti wire. Anodization was adopted for the conformal growth of TNTs on Ti wire, together with the simultaneous formation of a compact TiO2 layer. A sequential step dipping process is employed to produce a uniform and compact perovskite layer on top of TNTs with conformal coverage as the efficient light absorber. Transparent carbon nanotube film is wrapped around Ti wire as the hole collector and counter electrode. The integrated perovskite solar cell wire by facile fabrication approaches shows a promising future in portable and wearable textile electronics. PMID:27070991

  16. Vertically aligned nanostructured TiO2 photoelectrodes for high efficiency perovskite solar cells via a block copolymer template approach.

    PubMed

    Seo, Myung-Seok; Jeong, Inyoung; Park, Joon-Suh; Lee, Jinwoo; Han, Il Ki; Lee, Wan In; Son, Hae Jung; Sohn, Byeong-Hyeok; Ko, Min Jae

    2016-06-01

    We fabricated perovskite solar cells with enhanced device efficiency based on vertically oriented TiO2 nanostructures using a nanoporous template of block copolymers (BCPs). The dimension and shape controllability of the nanopores of the BCP template allowed for the construction of one-dimensional (1-D) TiO2 nanorods and two-dimensional (2-D) TiO2 nanowalls. The TiO2 nanorod-based perovskite solar cells showed a more efficient charge separation and a lower charge recombination, leading to better performance compared to TiO2 nanowall-based solar cells. The best solar cells employing 1-D TiO2 nanorods showed an efficiency of 15.5% with VOC = 1.02 V, JSC = 20.0 mA cm(-2) and fill factor = 76.1%. Thus, TiO2 nanostructures fabricated from BCP nanotemplates could be applied to the preparation of electron transport layers for improving the efficiency of perovskite solar cells.

  17. Improved efficiency of dye-sensitized solar cells applied with nanostructured N-F doped TiO2 electrode

    NASA Astrophysics Data System (ADS)

    Yang, Shuming; Xue, Hongbin; Wang, Hongjun; Kou, Huizhi; Wang, Jichao; Zhu, Guanghui

    2012-07-01

    Dye-sensitized solar cells (DSSCs) were fabricated with N-F-doped TiO2 electrodes. The XRD pattern of the N-F-doped TiO2 is almost the same as that of pure TiO2, showing that N and F doping has little influence on the formation of anatase titania. The influence of dopant N and F on band energetics and photoelectrochemical properties of nanostructured TiO2 electrodes were investigated. Compared with pure TiO2 electrodes, the Efb of N-F-doped TiO2 electrodes shifted a little in electrolytes containing LiClO4. However the total trap densities were remarkably decreased as TiO2 electrodes were doped with N and F. Finally the N-F-doped TiO2 electrodes were sensitized with N3 and their photoelectrochemical properties were studied. Experimental results showed that the photoelectric conversion efficiency of N3 sensitized N-F-doped TiO2 electrodes was 8.61% under irradiation of 100 mW cm-2 white light, about 17.1% higher than that of a pure TiO2 electrode.

  18. Improved conversion efficiency of dye sensitized solar cell using Zn doped TiO2-ZrO2 nanocomposite

    NASA Astrophysics Data System (ADS)

    Tomar, Laxmi J.; Bhatt, Piyush J.; Desai, Rahul K.; Chakrabarty, B. S.; Panchal, C. J.

    2016-05-01

    TiO2-ZrO2 and Zn doped TiO2-ZrO2 nanocomposites were prepared by hydrothermal method for dye sensitized solar cell (DSSC) application. The structural and optical properties were investigated by X -ray diffraction (XRD) and UV-Visible spectroscopy respectively. XRD results revealed the formation of material in nano size. The average crystallite size is 22.32 nm, 17.41 nm and 6.31 nm for TiO2, TiO2-ZrO2 and Zn doped TiO2-ZrO2 nanocomposites respectively. The optical bandgap varies from 2.04 eV to 3.75 eV. Dye sensitized solar cells were fabricated using the prepared material. Pomegranate juice was used as a sensitizer and graphite coated conducting glass plate was used as counter electrode. The I - V characteristics were recorded to measure photo response of DSSC. Photovoltaic parameter like open circuit voltage, power conversion efficiency, and fill factor were evaluated for fabricated solar cell. The power conversion efficiency of DSSC fabricated with TiO2, TiO2-ZrO2 and Zn doped TiO2-ZrO2 nanocomposites were found 0.71%, 1.97% and 4.58% respectively.

  19. Mesoporous TiO2 Nanowire Film for Dye-Sensitized Solar Cell.

    PubMed

    Xiao, Li; Xu, Jia; Liu, Xiu; Zhang, Yongzhe; Zhang, Bing; Yao, Jianxi; Dai, Songyuan; Tan, Zhanao; Pan, Xu

    2016-06-01

    In this work, TiO2 nanowire arrays were grown on fluorine-doped tin oxide (FTO) glass substrate, and then were converted into mesoporous nanowires (MNWs). The TiO2 MNWs are about 5 μm in length and 30-200 nm in diameter, with mesopores size of 5-30 nm randomly distributed on the NW surface. X-ray diffraction pattern reports show that the NWs are single crystallized rutile TiO2 and oriented grown along [001]. Through further characterization of FT-IR and TG-DSC, we proposed a reasonable explanation for pore existence. After dye-sensitized solar cells (DSSCs) assembly, the photoelectric conversion efficiency (PCE) of MNWs based DSSC achieved 3.2%. It means tenfold enhancement of photoelectric property compare with the as-grown NWs. Furthermore, dye absorb capacity of MNWs can reach up to 4.11 x 10(-8) mol/cm2. However, such MNWs can not only provide quick and efficient electron transmission channel, but also owns big specific surface area to absorb abundant dyes, thus conducive to fabricate solar cell with a high PCE.

  20. Mesoporous TiO2 Nanowire Film for Dye-Sensitized Solar Cell.

    PubMed

    Xiao, Li; Xu, Jia; Liu, Xiu; Zhang, Yongzhe; Zhang, Bing; Yao, Jianxi; Dai, Songyuan; Tan, Zhanao; Pan, Xu

    2016-06-01

    In this work, TiO2 nanowire arrays were grown on fluorine-doped tin oxide (FTO) glass substrate, and then were converted into mesoporous nanowires (MNWs). The TiO2 MNWs are about 5 μm in length and 30-200 nm in diameter, with mesopores size of 5-30 nm randomly distributed on the NW surface. X-ray diffraction pattern reports show that the NWs are single crystallized rutile TiO2 and oriented grown along [001]. Through further characterization of FT-IR and TG-DSC, we proposed a reasonable explanation for pore existence. After dye-sensitized solar cells (DSSCs) assembly, the photoelectric conversion efficiency (PCE) of MNWs based DSSC achieved 3.2%. It means tenfold enhancement of photoelectric property compare with the as-grown NWs. Furthermore, dye absorb capacity of MNWs can reach up to 4.11 x 10(-8) mol/cm2. However, such MNWs can not only provide quick and efficient electron transmission channel, but also owns big specific surface area to absorb abundant dyes, thus conducive to fabricate solar cell with a high PCE. PMID:27427603

  1. Aggregated TiO2 Based Nanotubes for Dye Sensitized Solar Cells

    SciTech Connect

    Nie, Zimin; Zhou, Xiaoyuan; Zhang, Qifeng; Cao, Guozhong; Liu, Jun

    2013-11-01

    One-dimensional (1D) semiconducting oxides have attracted great attention for dye sensitized solar cells (DSCs), but the overall performance is still quite limited as compared to TiO2 nanocrystalline DSCs. Here, we report the synthesis of aggregated TiO2 based nanotubes with controlled morphologies and crystalline structures to obtain an overall power conversion efficiency of 9.9% using conventional dye without any additional chemical treatment steps. The high efficiency is attributed to the unique aggregate structure for light harvesting, optimized high surface area, and good crystallinity of the nanotube aggregates obtained through proper thermal annealing. This study demonstrates that high efficiency DSCs can be obtained with 1D nanomaterials, and provides lessons on the importance of optimizing both the nanocrystalline structure and the overall microscale morphology.

  2. TiO2/Ni composite as antireflection coating for solar cell application

    NASA Astrophysics Data System (ADS)

    Haider, Adawiya J.; Najim, Aus A.; Muhi, Malik A. H.

    2016-07-01

    Titanium dioxide (TiO2) considered as one of the best material already used as a window in solar cells due to its antireflection capability. In this work, pure and Ni-doped (1, 3 and 5 wt%) TiO2 thin films were deposited using pulsed laser deposition (PLD) method. The optical measurements obtained by UV-vis indicate that the highest optical band gap was found with (5%) doping level (Eg=3.82 eV), corresponding to a lower reflectance and higher transmittance. Empirical equations between energy band gap and concentration level, reflectance with energy band gap, refractive index and concentration have been determined; a perfect fit with the experimental data was obtained.

  3. Low temperature synthesis of hierarchical TiO2 nanostructures for high performance perovskite solar cells by pulsed laser deposition

    DOE PAGES

    Yang, Bin; Mahjouri-Samani, Masoud; Rouleau, Christopher M.; Geohegan, David B.; Xiao, Kai

    2016-06-10

    A promising way to advance perovskite solar cells is to improve the quality of the electron transport material e.g., titanium dioxide (TiO2) in a direction that increases electron transport and extraction. Although dense TiO2 films are easily grown in solution, efficient electron extraction suffers due to a lack of interfacial contact area with the perovskite. Conversely, mesoporous films do offer high surface-area-to-volume ratios, thereby promoting efficient electron extraction, but their morphology is relatively difficult to control via conventional solution synthesis methods. Here, a pulsed laser deposition method was used to assemble TiO2 nanoparticles into TiO2 hierarchical nanoarchitectures having the anatasemore » crystal structure, and prototype solar cells employing these structures yielded power conversion efficiencies of ~ 14%. Our approach demonstrates a way to grow high aspect-ratio TiO2 nanostructures for improved interfacial contact between TiO2 and perovskite materials, leading to high electron-hole pair separation and electron extraction efficiencies for superior photovoltaic performance. In addition, compared to conventional solution-processed TiO2 films that require 500 °C to obtain a good crystallinity, our relatively low temperature (300 °C) TiO2 processing method may promote reduced energy-consumption during device fabrication as well as enable compatibility with various flexible polymer substrates.« less

  4. Nanostructured TiO2 films for dye-sensitized solar cells prepared by the sol-gel method.

    PubMed

    Jin, Young Sam; Kim, Kyung Hwan; Park, Sang Joon; Yoon, Hyon Hee; Choi, Hyung Wook

    2011-12-01

    TiO2 films were prepared on glass substrates using the sol-gel process for a dye-sensitized solar cell application. The TiO2 sol was prepared using hydrolysis/polycondensation. Titanium (IV) Tetra Isopropoxide (TTIP) was used as precursor and Nitric acid (HNO3) was used as a catalyst for the peptization. The crystal structure and morphology of the prepared materials were characterized by XRD, and an SEM. The observations confirmed the nanocrystalline nature of the TiO2. The reaction parameters, such as the catalyst concentrations, the calcination time, and the calcination temperature were varied during the synthesis in order to achieve nanosize TiO2 particles. The prepared TiO2 particles were coated onto FTO glass using a screen printing technique. The prepared TiO2 films were characterized by UV-vis. The TiO2 particles calcinated at low temperatures showed an anatase phase they grew into a rutile phase when the calcination temperature increased. The size and structure of the TiO2 particles were adjusted to specific surface areas. It was found that the conversion efficiency of the DSSC was highly affected by the properties of the TiO2 particles. PMID:22409037

  5. Nanostructured TiO2 films for dye-sensitized solar cells prepared by the sol-gel method.

    PubMed

    Jin, Young Sam; Kim, Kyung Hwan; Park, Sang Joon; Yoon, Hyon Hee; Choi, Hyung Wook

    2011-12-01

    TiO2 films were prepared on glass substrates using the sol-gel process for a dye-sensitized solar cell application. The TiO2 sol was prepared using hydrolysis/polycondensation. Titanium (IV) Tetra Isopropoxide (TTIP) was used as precursor and Nitric acid (HNO3) was used as a catalyst for the peptization. The crystal structure and morphology of the prepared materials were characterized by XRD, and an SEM. The observations confirmed the nanocrystalline nature of the TiO2. The reaction parameters, such as the catalyst concentrations, the calcination time, and the calcination temperature were varied during the synthesis in order to achieve nanosize TiO2 particles. The prepared TiO2 particles were coated onto FTO glass using a screen printing technique. The prepared TiO2 films were characterized by UV-vis. The TiO2 particles calcinated at low temperatures showed an anatase phase they grew into a rutile phase when the calcination temperature increased. The size and structure of the TiO2 particles were adjusted to specific surface areas. It was found that the conversion efficiency of the DSSC was highly affected by the properties of the TiO2 particles.

  6. Effect of sulfur doped TiO2 on photovoltaic properties of dye-sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Seo, Hyunwoong; Nam, Sang-Hun; Itagaki, Naho; Koga, Kazunori; Shiratani, Masaharu; Boo, Jin-Hyo

    2016-07-01

    In a dye-sensitized solar cell (DSC), a nano-porous semiconductor layer plays an important role in the performance. It determines open-circuit voltage and it affects the dye adsorption capacity and charge transfer, which are closely associated with photocurrent and overall performance. TiO2 is the most proper material for nano-porous layer since the first development of DSCs. This work focuses on the enhancement of TiO2 by doping. Sulfur (S) doping enhances charge transfer and the photoconversion of TiO2. Therefore, the increase in photocurrent and efficiency is expected by S doping. S is doped into TiO2 by hydrolysis method. The amount of S is varied and their photo-responses are verified. The most effective S doped TiO2 is applied to DSCs. Overall performance of DSC is enhanced by the addition of S doped TiO2. Especially, the photocurrent is much increased by the improvement on charge transfer, electron lifetime, and photo-conversion. The photovoltaic properties of DSCs are investigated with various ratios of undoped and S doped TiO2. Finally, a DSC based on undoped and S doped TiO2 ratio of 1:1 has the highest efficiency, better than that of a standard DSC based on undoped TiO2. [Figure not available: see fulltext.

  7. Interaction of Sensitizing Dyes with Nanostructured TiO2 Film in Dye-Sensitized Solar Cells Using Terahertz Spectroscopy

    PubMed Central

    Ghann, William; Rahman, Aunik; Rahman, Anis; Uddin, Jamal

    2016-01-01

    The objective of this investigation was to shed light on the nature of interaction of different organic dyes and an inorganic dye, Ruthenium (II) polypyridine complex, with TiO2 nanoparticles. TiO2 is commonly deployed as an efficient energy transfer electrode in dye sensitized solar cells. The efficiency of dye sensitized solar cells is a function of the interaction of a dye with the electrode material such as TiO2. To the best of our knowledge the present study is the first effort in the determination of terahertz absorbance signals, investigation of real-time dye permeation kinetics, and the surface profiling and 3D imaging of dye sensitized TiO2 films. Herein, we report that the terahertz spectra of the natural dye sensitized TiO2 films were distinctively different from that of the inorganic dye with prominent absorption of natural dyes occurring at approximately the same wavelength. It was observed that the permeation of the natural dyes were more uniform through the layers of the mesoporous TiO2 compared to the inorganic dye. Finally, defects and flaws on TiO2 film were easily recognized via surface profiling and 3D imaging of the films. The findings thus offer a new approach in characterization of dye sensitized solar cells. PMID:27443236

  8. Interaction of Sensitizing Dyes with Nanostructured TiO2 Film in Dye-Sensitized Solar Cells Using Terahertz Spectroscopy.

    PubMed

    Ghann, William; Rahman, Aunik; Rahman, Anis; Uddin, Jamal

    2016-07-22

    The objective of this investigation was to shed light on the nature of interaction of different organic dyes and an inorganic dye, Ruthenium (II) polypyridine complex, with TiO2 nanoparticles. TiO2 is commonly deployed as an efficient energy transfer electrode in dye sensitized solar cells. The efficiency of dye sensitized solar cells is a function of the interaction of a dye with the electrode material such as TiO2. To the best of our knowledge the present study is the first effort in the determination of terahertz absorbance signals, investigation of real-time dye permeation kinetics, and the surface profiling and 3D imaging of dye sensitized TiO2 films. Herein, we report that the terahertz spectra of the natural dye sensitized TiO2 films were distinctively different from that of the inorganic dye with prominent absorption of natural dyes occurring at approximately the same wavelength. It was observed that the permeation of the natural dyes were more uniform through the layers of the mesoporous TiO2 compared to the inorganic dye. Finally, defects and flaws on TiO2 film were easily recognized via surface profiling and 3D imaging of the films. The findings thus offer a new approach in characterization of dye sensitized solar cells.

  9. Interaction of Sensitizing Dyes with Nanostructured TiO2 Film in Dye-Sensitized Solar Cells Using Terahertz Spectroscopy

    NASA Astrophysics Data System (ADS)

    Ghann, William; Rahman, Aunik; Rahman, Anis; Uddin, Jamal

    2016-07-01

    The objective of this investigation was to shed light on the nature of interaction of different organic dyes and an inorganic dye, Ruthenium (II) polypyridine complex, with TiO2 nanoparticles. TiO2 is commonly deployed as an efficient energy transfer electrode in dye sensitized solar cells. The efficiency of dye sensitized solar cells is a function of the interaction of a dye with the electrode material such as TiO2. To the best of our knowledge the present study is the first effort in the determination of terahertz absorbance signals, investigation of real-time dye permeation kinetics, and the surface profiling and 3D imaging of dye sensitized TiO2 films. Herein, we report that the terahertz spectra of the natural dye sensitized TiO2 films were distinctively different from that of the inorganic dye with prominent absorption of natural dyes occurring at approximately the same wavelength. It was observed that the permeation of the natural dyes were more uniform through the layers of the mesoporous TiO2 compared to the inorganic dye. Finally, defects and flaws on TiO2 film were easily recognized via surface profiling and 3D imaging of the films. The findings thus offer a new approach in characterization of dye sensitized solar cells.

  10. Interaction of Sensitizing Dyes with Nanostructured TiO2 Film in Dye-Sensitized Solar Cells Using Terahertz Spectroscopy.

    PubMed

    Ghann, William; Rahman, Aunik; Rahman, Anis; Uddin, Jamal

    2016-01-01

    The objective of this investigation was to shed light on the nature of interaction of different organic dyes and an inorganic dye, Ruthenium (II) polypyridine complex, with TiO2 nanoparticles. TiO2 is commonly deployed as an efficient energy transfer electrode in dye sensitized solar cells. The efficiency of dye sensitized solar cells is a function of the interaction of a dye with the electrode material such as TiO2. To the best of our knowledge the present study is the first effort in the determination of terahertz absorbance signals, investigation of real-time dye permeation kinetics, and the surface profiling and 3D imaging of dye sensitized TiO2 films. Herein, we report that the terahertz spectra of the natural dye sensitized TiO2 films were distinctively different from that of the inorganic dye with prominent absorption of natural dyes occurring at approximately the same wavelength. It was observed that the permeation of the natural dyes were more uniform through the layers of the mesoporous TiO2 compared to the inorganic dye. Finally, defects and flaws on TiO2 film were easily recognized via surface profiling and 3D imaging of the films. The findings thus offer a new approach in characterization of dye sensitized solar cells. PMID:27443236

  11. Effect of Perovskite Overlayers on TiO2 Electrodes in Perovskite-Sensitized Solar Cells.

    PubMed

    Kim, Kang-Pil; Kim, Jeong-Hwa; Hwang, Dae-Kue

    2016-05-01

    In this paper, we have studied the effect of the thickness of a CH3NH3PbI3 perovskite overlayer on mesoporous TiO2 electrodes in perovskite solar cells. The overlayers were prepared by spin coating PbI2 films on the electrodes, which were subsequently exposed to a CH3NH3I/2-propanol solution. We controlled the thickness of the perovskite overlayer by changing the PbI2 solution concentration. The thicknesses of the overlayers spin-coated from 0.5, 0.75, 0.9, and 1 M PbI2 solutions were approximately 179, 262, 316, and 341 nm, respectively. Perovskite solar cells with an approximately 316-nm-thick overlayer showed the highest efficiency of 9.11%. We conclude that optimization of the perovskite overlayer thickness in the solar cell structure is necessary to improve the cell efficiency. PMID:27483921

  12. Chemical synthesis of CdS onto TiO2 nanorods for quantum dot sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Pawar, Sachin A.; Patil, Dipali S.; Lokhande, Abhishek C.; Gang, Myeng Gil; Shin, Jae Cheol; Patil, Pramod S.; Kim, Jin Hyeok

    2016-08-01

    A quantum dot sensitized solar cell (QDSSC) is fabricated using hydrothermally grown TiO2 nanorods and successive ionic layer adsorption and reaction (SILAR) deposited CdS. Surface morphology of the TiO2 films coated with different SILAR cycles of CdS is examined by Scanning Electron Microscopy which revealed aggregated CdS QDs coverage grow on increasing onto the TiO2 nanorods with respect to cycle number. Under AM 1.5G illumination, we found the TiO2/CdS QDSSC photoelectrode shows a power conversion efficiency of 1.75%, in an aqueous polysulfide electrolyte with short-circuit photocurrent density of 4.04 mA/cm2 which is higher than that of a bare TiO2 nanorods array.

  13. Hybrid bulk heterojunction solar cells from a blend of poly(3-hexylthiophene) and TiO 2 nanotubes

    NASA Astrophysics Data System (ADS)

    Wang, Z. J.; Qu, S. C.; Zeng, X. B.; Liu, J. P.; Zhang, C. S.; Tan, F. R.; Jin, L.; Wang, Z. G.

    2008-12-01

    Hybrid bulk heterojunction solar cells based on blend of poly(3-hexylthiophene) (P3HT) and TiO 2 nanotubes or dye(N719) modified TiO 2 nanotubes were processed from solution and characterized to research the nature of organic/inorganic hybrid materials. Compared with the pristine polymer P3HT and TiO 2 nanoparticles/P3HT solar cells, the TiO 2 nanotubes/P3HT hybrid solar cells show obvious performance improvement, due to the formation of the bulk heterojunction and charge transport improvement. A further improvement in the device performance can be achieved by modifying TiO 2 nanotube surface with a standard dye N719 which can play a role in the improvement of both the light absorption and charge dissociation. Compared with the non-modified TiO 2 nanotubes solar cells, the modified ones have better power conversion efficiency under 100 mW/cm 2 illumination with 500 W Xenon lamp.

  14. Hierarchical TiO2 photoanode for dye-sensitized solar cells.

    PubMed

    Sauvage, F; Di Fonzo, F; Li Bassi, A; Casari, C S; Russo, V; Divitini, G; Ducati, C; Bottani, C E; Comte, P; Graetzel, M

    2010-07-14

    Hierarchical or one-dimensional architectures are among the most exciting developments in material science these recent years. We present a nanostructured TiO(2) assembly combining these two concepts and resembling a forest composed of individual, high aspect-ratio, treelike nanostructures. We propose to use these structures for the photoanode in dye-sensitized solar cells, and we achieved 4.9% conversion efficiency in combination with C101 dye. We demonstrate this morphology beneficial to hamper the electron recombination and also mass transport control in the mesopores when solvent-free ionic liquid electrolyte is used.

  15. Opto-electronic properties of a TiO2/PS/mc-Si heterojunction based solar cell

    NASA Astrophysics Data System (ADS)

    Janene, N.; Ghrairi, N.; Allagui, A.; Alawadhi, H.; Khakani, M. A. El; Bessais, B.; Gaidi, M.

    2016-04-01

    In this work, we show the results of our investigation on the photoelectric properties of heterojunction solar cells based on Au/PS/mc-Si/Al and Au/TiO2/PS/mc-Si/Al structures. Porous silicon (PS) were prepared by an electrochemical etching process with different values of current density. The surface porosity was found to increase with the increase of current density. Pulsed laser deposition was used to deposit 80 nm TiO2 thin films. Surface morphology and structural properties of TiO2/PS were characterized by using scanning electron microscopy (SEM) and atomic force microscopy (AFM). An enhancement of the electrical properties of the TiO2/PS/mc-Si heterojunction was observed after coating with TiO2. As a consequence, the solar cell efficiencies increased from 1.4% for the uncoated PS/mc-Si structure to 5% for the TiO2 coated one. Impedance spectroscopy confirmed the passivation effect of TiO2 through the improvement of the elaborated cells' electron lifetime and the formation of a TiO2/PS/Au heterojunction with the appearance of a second semi-circle in the Nyquist plot.

  16. Hierarchical Oriented Anatase TiO2 Nanostructure arrays on Flexible Substrate for Efficient Dye-sensitized Solar Cells

    PubMed Central

    Wu, Wu-Qiang; Rao, Hua-Shang; Xu, Yang-Fan; Wang, Yu-Fen; Su, Cheng-Yong; Kuang, Dai-Bin

    2013-01-01

    The vertically oriented anatase single crystalline TiO2 nanostructure arrays (TNAs) consisting of TiO2 truncated octahedrons with exposed {001} facets or hierarchical TiO2 nanotubes (HNTs) consisting of numerous nanocrystals on Ti-foil substrate were synthesized via a two-step hydrothermal growth process. The first step hydrothermal reaction of Ti foil and NaOH leads to the formation of H-titanate nanowire arrays, which is further performed the second step hydrothermal reaction to obtain the oriented anatase single crystalline TiO2 nanostructures such as TiO2 nanoarrays assembly with truncated octahedral TiO2 nanocrystals in the presence of NH4F aqueous or hierarchical TiO2 nanotubes with walls made of nanocrystals in the presence of pure water. Subsequently, these TiO2 nanostructures were utilized to produce dye-sensitized solar cells in a backside illumination pattern, yielding a significant high power conversion efficiency (PCE) of 4.66% (TNAs, JSC = 7.46 mA cm−2, VOC = 839 mV, FF = 0.75) and 5.84% (HNTs, JSC = 10.02 mA cm−2, VOC = 817 mV, FF = 0.72), respectively. PMID:23715529

  17. Tailoring the interface using thiophene small molecules in TiO2/P3HT hybrid solar cells.

    PubMed

    Freitas, Flavio S; Clifford, John N; Palomares, Emilio; Nogueira, Ana F

    2012-09-14

    In this paper we focus on the effect of carboxylated thiophene small molecules as interface modifiers in TiO(2)/P3HT hybrid solar cells. Our results show that small differences in the chemical structure of these molecules, for example, the presence of the -CH(2)- group in the 2-thiopheneacetic acid (TAA), can greatly increase the TiO(2) surface wettability, improving the TiO(2)/polymer contact. This effect is important to enhance exciton splitting and charge separation. PMID:22842849

  18. Electron-Selective TiO2 Contact for Cu(In,Ga)Se2 Solar Cells

    NASA Astrophysics Data System (ADS)

    Hsu, Weitse; Sutter-Fella, Carolin M.; Hettick, Mark; Cheng, Lungteng; Chan, Shengwen; Chen, Yunfeng; Zeng, Yuping; Zheng, Maxwell; Wang, Hsin-Ping; Chiang, Chien-Chih; Javey, Ali

    2015-11-01

    The non-toxic and wide bandgap material TiO2 is explored as an n-type buffer layer on p-type Cu(In,Ga)Se2 (CIGS) absorber layer for thin film solar cells. The amorphous TiO2 thin film deposited by atomic layer deposition process at low temperatures shows conformal coverage on the CIGS absorber layer. Solar cells from non-vacuum deposited CIGS absorbers with TiO2 buffer layer result in a high short-circuit current density of 38.9 mA/cm2 as compared to 36.9 mA/cm2 measured in the reference cell with CdS buffer layer, without compromising open-circuit voltage. The significant photocurrent gain, mainly in the UV part of the spectrum, can be attributed to the low parasitic absorption loss in the ultrathin TiO2 layer (~10 nm) with a larger bandgap of 3.4 eV compared to 2.4 eV of the traditionally used CdS. Overall the solar cell conversion efficiency was improved from 9.5% to 9.9% by substituting the CdS by TiO2 on an active cell area of 10.5 mm2. Optimized TiO2/CIGS solar cells show excellent long-term stability. The results imply that TiO2 is a promising buffer layer material for CIGS solar cells, avoiding the toxic CdS buffer layer with added performance advantage.

  19. Electron-Selective TiO2 Contact for Cu(In,Ga)Se2 Solar Cells

    DOE PAGES

    Hsu, Weitse; Sutter-Fella, Carolin M.; Hettick, Mark; Cheng, Lungteng; Chan, Shengwen; Chen, Yunfeng; Zeng, Yuping; Zheng, Maxwell; Wang, Hsin-Ping; Chiang, Chien-Chih; et al

    2015-11-03

    The non-toxic and wide bandgap material TiO2 is explored as an n-type buffer layer on p-type Cu(In,Ga)Se2 (CIGS) absorber layer for thin film solar cells. The amorphous TiO2 thin film deposited by atomic layer deposition process at low temperatures shows conformal coverage on the CIGS absorber layer. Solar cells from non-vacuum deposited CIGS absorbers with TiO2 buffer layer result in a high short-circuit current density of 38.9 mA/cm2 as compared to 36.9 mA/cm2 measured in the reference cell with CdS buffer layer, without compromising open-circuit voltage. The significant photocurrent gain, mainly in the UV part of the spectrum, can bemore » attributed to the low parasitic absorption loss in the ultrathin TiO2 layer (~10 nm) with a larger bandgap of 3.4 eV compared to 2.4 eV of the traditionally used CdS. Overall the solar cell conversion efficiency was improved from 9.5% to 9.9% by substituting the CdS by TiO2 on an active cell area of 10.5 mm2. In conclusion, optimized TiO2/CIGS solar cells show excellent long-term stability. The results imply that TiO2 is a promising buffer layer material for CIGS solar cells, avoiding the toxic CdS buffer layer with added performance advantage.« less

  20. Electron-Selective TiO2 Contact for Cu(In,Ga)Se2 Solar Cells

    PubMed Central

    Hsu, Weitse; Sutter-Fella, Carolin M.; Hettick, Mark; Cheng, Lungteng; Chan, Shengwen; Chen, Yunfeng; Zeng, Yuping; Zheng, Maxwell; Wang, Hsin-Ping; Chiang, Chien-Chih; Javey, Ali

    2015-01-01

    The non-toxic and wide bandgap material TiO2 is explored as an n-type buffer layer on p-type Cu(In,Ga)Se2 (CIGS) absorber layer for thin film solar cells. The amorphous TiO2 thin film deposited by atomic layer deposition process at low temperatures shows conformal coverage on the CIGS absorber layer. Solar cells from non-vacuum deposited CIGS absorbers with TiO2 buffer layer result in a high short-circuit current density of 38.9 mA/cm2 as compared to 36.9 mA/cm2 measured in the reference cell with CdS buffer layer, without compromising open-circuit voltage. The significant photocurrent gain, mainly in the UV part of the spectrum, can be attributed to the low parasitic absorption loss in the ultrathin TiO2 layer (~10 nm) with a larger bandgap of 3.4 eV compared to 2.4 eV of the traditionally used CdS. Overall the solar cell conversion efficiency was improved from 9.5% to 9.9% by substituting the CdS by TiO2 on an active cell area of 10.5 mm2. Optimized TiO2/CIGS solar cells show excellent long-term stability. The results imply that TiO2 is a promising buffer layer material for CIGS solar cells, avoiding the toxic CdS buffer layer with added performance advantage. PMID:26526426

  1. Photochemical solar cells based on dye-sensitization of nanocrystalline TiO2

    NASA Astrophysics Data System (ADS)

    Frank, A. J.; Gregg, B. A.; Grätzel, M.; Nozik, A. J.; Zaban, A.; Ferrere, S.; Schlichthörl, G.; Huang, S. Y.

    1997-04-01

    A new type of photovoltaic cell is described. It is a photoelectrochemical device that is based on the dye sensitization of thin (10-30 μm) films of TiO2 nanoparticles in contact with a non-aqueous liquid electrolyte. The cell is very simple to fabricate and, in principle, its color can be tuned through the visible spectrum, ranging from being completely transparent to black by changing the absorption characteristics of the dye; the photovoltage of the cell is not determined by the threshold energy for light absorption (bandgap) as in conventional photovoltaic cells based on solid-state semiconductors. The highest present efficiency of the dye-sensitized photochemical solar cell is about 11%. The cell has the potential to be a low-cost photovoltaic option. Unique applications include photovoltaic power windows and photoelectrochromic windows.

  2. Hyperbranched quasi-1D TiO2 nanostructure for hybrid organic-inorganic solar cells.

    PubMed

    Ghadirzadeh, Ali; Passoni, Luca; Grancini, Giulia; Terraneo, Giancarlo; Li Bassi, Andrea; Petrozza, Annamaria; Di Fonzo, Fabio

    2015-04-15

    The performance of hybrid solar cells is strongly affected by the device morphology. In this work, we demonstrate a poly(3-hexylthiophene-2,5-diyl)/TiO2 hybrid solar cell where the TiO2 photoanode comprises an array of tree-like hyperbranched quasi-1D nanostructures self-assembled from the gas phase. This advanced architecture enables us to increase the power conversion efficiency to over 1%, doubling the efficiency with respect to state of the art devices employing standard mesoporous titania photoanodes. This improvement is attributed to several peculiar features of this array of nanostructures: high interfacial area; increased optical density thanks to the enhanced light scattering; and enhanced crystallization of poly(3-hexylthiophene-2,5-diyl) inside the quasi-1D nanostructure. PMID:25822757

  3. Enhancing the efficiency of dye-sensitized solar cells by adding diatom frustules into TiO2 working electrodes

    NASA Astrophysics Data System (ADS)

    Huang, Der-Ray; Jiang, Yan-Jang; Liou, Run-Lin; Chen, Chih-Han; Chen, Yi-An; Tsai, Chih-Hung

    2015-08-01

    In this study, diatom frustules were added into TiO2 paste to prepare a TiO2-diatom paste mixture. Spin-coating and high-temperature sintering techniques were then used to fabricate working electrodes for dye-sensitized solar cells (DSSCs). Mixing the diatom frustules with the TiO2 paste improved the light-trapping effect and scattering properties of the incident light in the TiO2-diatom working electrodes, thereby enhancing the power conversion efficiency of the DSSCs. In this study, a high-speed centrifugal processing technology and sedimentation-rate separation techniques were first used to obtain the diatom frustules, which were then mixed with the TiO2 paste at a weight ratio of 1:50; a spin-coating technique was then used to fabricate the working electrodes. Finally, a high-temperature sintering process (500 °C) was performed. In this study, optical microscopy, scanning electron microscopy, atomic force microscopy, X-ray photoelectron spectroscopy, Raman spectroscopy, and a surface profiler and spectrometer were used to analyze the characteristics of the working electrodes. The TiO2 or TiO2-diatom working electrodes were prepared under various spin-coating conditions for fabricating and analyzing the characteristics of the DSSCs. The results indicated that under identical conditions, the power conversion efficiency of the DSSCs was 3.81% when coated three times with a conventional TiO2 paste, and 5.26% when coated once with the TiO2-diatom paste before being coated twice again with the TiO2 paste, indicating a 38% increase in efficiency.

  4. Sea grass like arranged TiO2 nanorods sensitized by natural dyes for solar cell applications

    NASA Astrophysics Data System (ADS)

    Akila, Y.; Muthukumarasamy, N.; Agilan, S.; Senthilarasu, S.; Velauthapillai, Dhayalan

    2016-08-01

    Rutile-phase seagrass-like-arranged TiO2 nanorods have been synthesized by low-temperature template-free hydrothermal method. These TiO2 nanorods have been sensitized by flowers of Sesbania grandiflora, leaves of Camellia sinensis and roots of Rubia tinctorum. The sensitized TiO2 nanorods-based films have been used as photoanode in natural dye-sensitized solar cells. The films were photoelectrochemically active, and the fabricated solar cells had short-circuit photocurrent density (JSC) lying in the range of 3.7-4.7mAcm-2. The efficiency of the fabricated natural dye-sensitized solar cells was found to lie in the range of 0.6-1.036 %, respectively

  5. Surfactant free most probable TiO2 nanostructures via hydrothermal and its dye sensitized solar cell properties

    PubMed Central

    Mali, Sawanta S.; Kim, Hyungjin; Shim, Chang Su; Patil, Pramod S.; Kim, Jin Hyeok; Hong, Chang Kook

    2013-01-01

    Tailoring the nano-morphology and nano-architecture of titanium dioxide (TiO2) is the most important task in the third generation solar cells (Dye sensitized solar cells/Quantum dot sensitized solar cells) (DSSCs/QDSSCs). In this article we present complete study of surfactant free synthesis of TiO2 nanostructures by a simple and promising hydrothermal route. The plethora of nanostructures like nanoparticles clusters, 1D tetragonal nanorods, 3D dendrites containing nanorods having <30 nm diameter and 3D hollow urchin like have been synthesized. These nanostructures possess effective large surface area and thus useful in DSSCs. In the present work, 7.16% power conversion efficiency has been demonstrated for 3D dendritic hollow urchin like morphology. Our synthetic strategy provides an effective solution for surfactant free synthesis of efficient TiO2 nanoarchitectures. PMID:24141599

  6. Basella alba rubra spinach pigment-sensitized TiO2 thin film-based solar cells

    NASA Astrophysics Data System (ADS)

    Gokilamani, N.; Muthukumarasamy, N.; Thambidurai, M.; Ranjitha, A.; Velauthapillai, Dhayalan

    2015-03-01

    Nanocrystalline TiO2 thin films have been prepared by sol-gel dip coating method. The X-ray diffraction results showed that TiO2 thin films annealed at 400, 450 and 500 °C are of anatase phase and the peak corresponding to the (101) plane is present in all the samples. The grain size of TiO2 thin films was found to increase with increasing annealing temperature. The grain size is found to be 20, 25 and 33 nm for the films annealed at 400, 450 and 500 °C. The structure of the TiO2 nanocrystalline thin films have been examined by high-resolution transmission electron microscope, Raman spectroscopy and FTIR spectroscopy. TiO2 thin films were sensitized by natural dyes extracted from basella alba rubra spinach. It was found that the absorption peak of basella alba rubra extract is at about 665 nm. The dye-sensitized TiO2-based solar cell sensitized using basella alba rubra exhibited a J sc of 4.35 mA cm-2, V oc of 0.48 V, FF of 0.35 and efficiency of 0.70 %. Natural dyes as sensitizers for dye-sensitized solar cells are promising because of their environmental friendliness, low-cost production and fully biodegradable.

  7. Synthesis of TiO2 microspheres building on the etherification and its application for high efficiency solar cells

    NASA Astrophysics Data System (ADS)

    Liu, Shi-Dong; Ren, Ying-Ke; Zhou, Zheng; Chen, Wang-Chao; Li, Zhao-Qian; Guo, Fu-Ling; Mo, Li-E.; Wu, Ji-Huai; Hu, Lin-Hua; Dai, Song-Yuan

    2016-10-01

    This paper describes a facile solvothermal method to synthesize TiO2 microspheres by employing ethylene glycol monomethyl ether and ethylene glycol as solvent. By analyzing the resulted supernatant after reaction, it was proved that the etherification reaction of glycol monomethyl ether and the ligand exchange between ethylene glycol and tetra-n-butyl titanate played a key role in synthesis of TiO2 microspheres. These as-obtained TiO2 microspheres exhibited high specific surface area up to 113.24 m2 g-1 and have a narrow pore size distribution (6.94 nm). When applied to the photoanode, the TiO2 microsphere-based dye-sensitized solar cells achieved a high power conversion efficiency up to 10.25%.

  8. Mesoporous nitrogen-doped TiO2 sphere applied for quasi-solid-state dye-sensitized solar cell

    PubMed Central

    2011-01-01

    A mesoscopic nitrogen-doped TiO2 sphere has been developed for a quasi-solid-state dye-sensitized solar cell [DSSC]. Compared with the undoped TiO2 sphere, the quasi-solid-state DSSC based on the nitrogen-doped TiO2 sphere shows more excellent photovoltaic performance. The photoelectrochemistry of electrodes based on nitrogen-doped and undoped TiO2 spheres was characterized with Mott-Schottky analysis, intensity modulated photocurrent spectroscopy, and electrochemical impedance spectroscopy, which indicated that both the quasi-Fermi level and the charge transport of the photoelectrode were improved after being doped with nitrogen. As a result, a photoelectric conversion efficiency of 6.01% was obtained for the quasi-solid-state DSSC. PMID:22115421

  9. Facile and effective synthesis of hierarchical TiO2 spheres for efficient dye-sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Ye, Meidan; Chen, Chang; Lv, Miaoqiang; Zheng, Dajiang; Guo, Wenxi; Lin, Changjian

    2013-06-01

    Three-dimensional (3D) crystalline anatase TiO2 hierarchical spheres were successfully derived from Ti foils via a fast, template-free, low-temperature hydrothermal route followed by a calcination post-treatment. These dandelion-like TiO2 spheres are composed of numerous ultrathin nanoribbons, which were subsequently split into fragile nanoflakes as a result of the decomposition of Ti-complex intermediates to TiO2 and H2O at high temperature. The dye-sensitized solar cells (DSSCs) employing such hierarchically structured TiO2 spheres as the photoanodes exhibited a light-to-electricity conversion efficiency of 8.50%, yielding a 28% enhancement in comparison with that (6.64%) of P25-based DSSCs, which mainly benefited from the enhanced capacity of dye loading in combination with effective light scattering and trapping from hierarchical architecture.Three-dimensional (3D) crystalline anatase TiO2 hierarchical spheres were successfully derived from Ti foils via a fast, template-free, low-temperature hydrothermal route followed by a calcination post-treatment. These dandelion-like TiO2 spheres are composed of numerous ultrathin nanoribbons, which were subsequently split into fragile nanoflakes as a result of the decomposition of Ti-complex intermediates to TiO2 and H2O at high temperature. The dye-sensitized solar cells (DSSCs) employing such hierarchically structured TiO2 spheres as the photoanodes exhibited a light-to-electricity conversion efficiency of 8.50%, yielding a 28% enhancement in comparison with that (6.64%) of P25-based DSSCs, which mainly benefited from the enhanced capacity of dye loading in combination with effective light scattering and trapping from hierarchical architecture. Electronic supplementary information (ESI) available: FESEM images of samples prepared in other control experiments and a cross-sectional view of the three films. See DOI: 10.1039/c3nr01604h

  10. Influences of Sr-Incorporated TiO2 Layer on the Photovoltaic Properties of Dye-Sensitized Solar Cells.

    PubMed

    Kim, Eun Seong; Kim, Dae-Hwan; Lee, Sang-Ju; Han, Yoon Soo

    2016-03-01

    Effects of a mixed overlayer composed of TiO2 and TiSrO3 on the performance of dye-sensitized solar cells (DSSCs) were investigated. The surface of TiO2 photoelectrode formed on F-doped SnO2 (FTO) was modified by soaking it in a TiCl4:SrCl2 mixed aqueous solution with various molar ratios and then calcining to produce the TiCl4:SrCl2-treated TiO2 photoelectrode (Ti:Sr-TiO2/FTO). The highest power conversion efficiency (PCE) was obtained from DSSC with Ti:Sr(7:3)-TiO2/FTO, which was prepared from the mixed solution with the molar ratio of 7:3 (TiOl4:SrCl2). An enhancement in short-circuit photocurrent (J(sc)) and open-circuit voltage (V(oc)) of DSSC with Ti:Sr(7:3)-TiO2/FTO was achieved, compared to those of the reference device with Ti:Sr(10:0)-TiC2/FTO (i.e., TiO2-coated TiO2/FTO). The incorporation of the mixed overlayer on the nanoporous TiO2 photoelectorde led to an improvement in the electron collection efficiency by a prolonged electron lifetime, thereby increasing the J(sc) value. The increase in V(oc) value of the device with Ti:Sr(7:3)-TiO2/FTO was due to the suppression of the charge recombination between injected electrons and I3(-) ions.

  11. Conical islands of TiO2 nanotube arrays in the photoelectrode of dye-sensitized solar cells.

    PubMed

    Kim, Woong-Rae; Park, Hun; Choi, Won-Youl

    2015-01-01

    Ti conical island structures were fabricated using photolithography and the reactive ion etching method. The resulting conical island structures were anodized in ethylene glycol solution containing 0.25 wt% NH4F and 2 vol% H2O, and conical islands composed of TiO2 nanotubes were successfully formed on the Ti foils. The conical islands composed of TiO2 nanotubes were employed in photoelectrodes for dye-sensitized solar cells (DSCs). DSC photoelectrodes based on planar Ti structures covered with TiO2 nanotubes were also fabricated as a reference. The short-circuit current (J sc) and efficiency of DSCs based on the conical island structures were higher than those of the reference samples. The efficiency of DSCs based on the conical island structures reached up to 1.866%. From electrochemical impedance spectroscopy and open-circuit voltage (V oc) decay measurements, DSCs based on the conical island structures exhibited a lower charge transfer resistance at the counter cathode and a longer electron lifetime at the interface of the photoelectrode and electrolyte compared to the reference samples. The conical island structure was very effective at improving performances of DSCs based on TiO2 nanotubes. Graphical AbstractConical islands of TiO2 nanotube arrays are fabricated by an anodizing process with Ti protruding dots which have a conical shape. The conical islands are applied for use in DSC photoelectrodes. DSCs based on the conical islands of TiO2 nanotube arrays have the potential to achieve higher efficiency levels compared to DSCs based on normal TiO2 nanotubes and TiO2 nanoparticles because the conical islands of TiO2 nanotube arrays enlarge the surface area for dye adsorption.

  12. Improved solar efficiency by introducing graphene oxide in purple cabbage dye sensitized TiO2 based solar cell

    NASA Astrophysics Data System (ADS)

    Al-Ghamdi, Ahmed A.; Gupta, R. K.; Kahol, P. K.; Wageh, S.; Al-Turki, Y. A.; El Shirbeeny, W.; Yakuphanoglu, F.

    2014-04-01

    Natural dye extracted from purple cabbage was used for fabrication of TiO2 dye-sensitized solar cells (DSSCs). The effect of light intensity on the solar efficiency of the device was investigated. It was observed that the efficiency of the DSSC increases with increasing the light intensity e.g. the efficiency of the solar cell increases from 0.013±0.002% to 0.150±0.020% by increase in light intensity from 30 to 100 mW/cm2, respectively. The solar efficiency of the natural dye used in this research was compared with commercial dye (N 719) under similar experimental conditions and observed that the natural (purple cabbage) dye has higher efficiency (0.150±0.020%) than N 719 (0.078±0.002%). It was further evaluated that the efficiency of the fabricated solar cell could improve by incorporating graphene oxide. The efficiency of the TiO2 dye-sensitized solar cell was found to increase from 0.150±0.020% to 0.361±0.009% by incorporating graphene oxide into purple cabbage dye.

  13. Photovoltaic performance of dye-sensitized solar cells using TiO2 nanotubes aggregates produced by hydrothermal synthesis

    NASA Astrophysics Data System (ADS)

    Chen, Qiufan; Sun, Xiaonan; Liu, Anping; Zhang, Qifeng; Cao, Guozhong; Zhou, Xiaoyuan

    2015-09-01

    This paper reports the synthesis, detailed structural characterization of aggregated TiO2 nanotubes and the application of such aggregated TiO2 nanotubes as photoelectrodes in solar cells (dye sensitized DSCs). A maximum overall conversion efficiency of 7.9% has been achieved, which use conventional dyes without any additional chemical treatments under circumstances of an open-circuit voltage of 710 mV, a short-circuit current density of 16.8mA/cm2, and a fill factor of 66%. This impressive performance is believed to attribute to the micron-sized aggregate structure which may be favorable for light harvesting, the desired high specific surface area and pure anatase phase for dye absorption. This significant improvement in the conversion efficiency indicates that DSCs based on aggregated TiO2 nanotubes are a promising alternative to semiconductor-based solar cells.

  14. Enhancement of the photoelectric performance of dye-sensitized solar cells using Ag-doped TiO2 nanofibers in a TiO2 film as electrode.

    PubMed

    Jin, En Mei; Zhao, Xing Guan; Park, Ju-Young; Gu, Hal-Bon

    2012-01-01

    For high solar conversion efficiency of dye-sensitized solar cells [DSSCs], TiO2 nanofiber [TN] and Ag-doped TiO2 nanofiber [ATN] have been extended to be included in TiO2 films to increase the amount of dye loading for a higher short-circuit current. The ATN was used on affected DSSCs to increase the open circuit voltage. This process had enhanced the exit in dye molecules which were rapidly split into electrons, and the DSSCs with ATN stop the recombination of the electronic process. The conversion efficiency of TiO2 photoelectrode-based DSSCs was 4.74%; it was increased to 6.13% after adding 5 wt.% ATN into TiO2 films. The electron lifetime of DSSCs with ATN increased from 0.29 to 0.34 s and that electron recombination was reduced.

  15. Improve efficiency of perovskite solar cells by using Magnesium doped ZnO and TiO2 compact layers

    NASA Astrophysics Data System (ADS)

    Baktash, Ardeshir; Amiri, Omid; Sasani, Alireza

    2016-05-01

    Here the effect of Magnesium doped TiO2 and ZnO as hole blocking layers (HBLs) are investigated by using solar cell capacitance simulator (SCAPS). The Impact of Magnesium concentration into the TiO2 and ZnO and effect of operating temperature on the performance of the perovskite solar cell are investigated. Best cell performance for both TiO2 and ZnO HBLs (with cell efficiencies of 19.86% and 19.57% respectively) are concluded for the doping level of 10% of Mg into the structure of HBLs. Increase in operating temperature from 300 K to 400 K are decreased the performance of the perovskite solar cell with both pure and Mg-doped HBLs. However, the cells with pure ZnO layer and with Zn0.9 Mg0.1O layer show the highest (with a decline of 8.88% in efficiency) and the lowest stability (with a decline of 50.49% in efficiency) at higher temperatures respectively. Moreover, the cell with Ti0.9 Mg0.1O2 layer shows better stability (with 21.85% reduction in efficiency) than the cell with pure TiO2 compact layer (with 23.28% reduction in efficiency) at higher operating temperatures.

  16. The effect of dye-sensitized solar cell based on the composite layer by anodic TiO2 nanotubes

    NASA Astrophysics Data System (ADS)

    Yang, Jun Hyuk; Kim, Kyung Hwan; Bark, Chung Wung; Choi, Hyung Wook

    2014-12-01

    TiO2 nanotube arrays are very attractive for dye-sensitized solar cells (DSSCs) owing to their superior charge percolation and slower charge recombination. Highly ordered, vertically aligned TiO2 nanotube arrays have been fabricated by a three-step anodization process. Although the use of a one-dimensional structure provides an enhanced photoelectrical performance, the smaller surface area reduces the adsorption of dye on the TiO2 surface. To overcome this problem, we investigated the effect of DSSCs constructed with a multilayer photoelectrode made of TiO2 nanoparticles and TiO2 nanotube arrays. We fabricated the novel multilayer photoelectrode via a layer-by-layer assembly process and thoroughly investigated the effect of various structures on the sample efficiency. The DSSC with a four-layer photoelectrode exhibited a maximum conversion efficiency of 7.22% because of effective electron transport and enhanced adsorption of dye on the TiO2 surface.

  17. Ultra-High Speed Fabrication of TiO2 Photoanode by Flash Light for Dye-Sensitized Solar Cell.

    PubMed

    Hwang, Hyun-Jun; Kim, Hak-Sung

    2015-07-01

    In this work, a new way to fabricate nanoporous TiO2 photoanode by flash light is demonstrated. TiO2 nanoparticles are sintered on FTO glass by flash light irradiation at room temperature in ambient condition, which is dramatically simple, ultrahigh speed and one-shot large area fabrication process compared to a conventional high temperature (120 °C) thermal sintering process. The effect of the flash light conditions (flash light energy, pulse numbers and pulse duration) on the nanostructures of sintered TiO2 layer, was studied and discussed using several microscopic and spectroscopic characterization techniques such as SEM, FT-IR, XRD and XPS. The sintered TiO2 photoanodes by flash light were used in DSSC and its performance were compared with that of DSSC fabricated by conventional thermal sintering process. It was found that a flash light sintered TiO2 photoanode has efficiency which is similar to that of the thermal sintered photoanode. It is expected that the newly developed flash light sintering technique of TiO2 nanoparticles would be a strong alternative to realize the room temperature and in-situ sintering of photoanode fabrication for outdoor solar cell fabrication.

  18. Energy level alignment in TiO2/metal sulfide/polymer interfaces for solar cell applications.

    PubMed

    Lindblad, Rebecka; Cappel, Ute B; O'Mahony, Flannan T F; Siegbahn, Hans; Johansson, Erik M J; Haque, Saif A; Rensmo, Håkan

    2014-08-28

    Semiconductor sensitized solar cell interfaces have been studied with photoelectron spectroscopy to understand the interfacial electronic structures. In particular, the experimental energy level alignment has been determined for complete TiO2/metal sulfide/polymer interfaces. For the metal sulfides CdS, Sb2S3 and Bi2S3 deposited from single source metal xanthate precursors, it was shown that both driving forces for electron injection into TiO2 and hole transfer to the polymer decrease for narrower bandgaps. The energy level alignment results were used in the discussion of the function of solar cells with the same metal sulfides as light absorbers. For example Sb2S3 showed the most favourable energy level alignment with 0.3 eV driving force for electron injection and 0.4 eV driving force for hole transfer and also the most efficient solar cells due to high photocurrent generation. The energy level alignment of the TiO2/Bi2S3 interface on the other hand showed no driving force for electron injection to TiO2, and the performance of the corresponding solar cell was very low.

  19. Preparation of TiO2 nanotube/nanoparticle composite particles and their applications in dye-sensitized solar cells

    PubMed Central

    2012-01-01

    Efficiency of dye-sensitized solar cells [DSSCs] was enhanced by combining the use of TiO2 nanotubes [TNTs] and nanoparticles. TNTs were fabricated by a sol-gel method, and TiO2 powders were produced through an alkali hydrothermal transformation. DSSCs were constructed using TNTs and TiO2 nanoparticles at various weight percentages. TNTs and TiO2 nanoparticles were coated onto FTO glass by the screen printing method. The DSSCs were fabricated using ruthenium(II) (N-719) and electrolyte (I3/I3-) dyes. The crystalline structure and morphology were characterized by X-ray diffraction and using a scanning electron microscope. The absorption spectra were measured using an UV-Vis spectrometer. The incident photocurrent conversion efficiency was measured using a solar simulator (100 mW/cm2). The DSSCs based on TNT/TiO2 nanoparticle hybrids showed better photovoltaic performance than cells made purely of TiO2 nanoparticles. PMID:22222095

  20. Highly efficient solar cells using TiO(2) nanotube arrays sensitized with a donor-antenna dye.

    PubMed

    Shankar, Karthik; Bandara, Jayasundera; Paulose, Maggie; Wietasch, Helga; Varghese, Oomman K; Mor, Gopal K; LaTempa, Thomas J; Thelakkat, Mukundan; Grimes, Craig A

    2008-06-01

    Donor antenna dyes provide an exciting route to improving the efficiency of dye sensitized solar cells owing to their high molar extinction coefficients and the effective spatial separation of charges in the charge-separated state, which decelerates the recombination of photogenerated charges. Vertically oriented TiO(2) nanotube arrays provide an optimal material architecture for photoelectrochemical devices because of their large internal surface area, lower recombination losses, and vectorial charge transport along the nanotube axis. In this study, the results obtained by sensitizing TiO(2) nanotube arrays with the donor antenna dye Ru-TPA-NCS are presented. Solar cells fabricated using an antenna dye-sensitized array of 14.4 microm long TiO(2) nanotubes on Ti foil subjected to AM 1.5 one sun illumination in the backside geometry exhibited an overall conversion efficiency of 6.1%. An efficiency of 4.1% was obtained in the frontside illumination geometry using a 1 microm long array of transparent TiO(2) nanotubes subjected to a TiCl(4) treatment and then sensitized with the Ru-TPA-NCS dye. Open circuit voltage decay measurements give insight into the recombination behavior in antenna-dye sensitized nanotube photoelectrodes, demonstrating outstanding properties likely due to a reduction in the influence of the surface traps and reduced electron transfer from TiO(2) to ions in solution.

  1. Dye-sensitized solar cells based on anatase TiO 2 hollow spheres/carbon nanotube composite films

    NASA Astrophysics Data System (ADS)

    Yu, Jiaguo; Fan, Jiajie; Cheng, Bei

    Dye-sensitized solar cells (DSSCs) based on anatase TiO 2 hollow spheres (TiO2HS)/multi-walled carbon nanotubes (CNT) nanocomposite films are prepared by a directly mechanical mixing and doctor blade method. The prepared samples are characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, UV-vis absorption spectroscopy and N 2 adsorption-desorption isotherms. The photoelectric conversion performances of the DSSCs based on TiO2HS/CNT composite film electrodes are also compared with commercial-grade Degussa P25 TiO 2 nanoparticles (P25)/CNT composite solar cells at the same film thickness. The results indicate that the photoelectric conversion efficiencies (η) of the TiO2HS/CNT composite DSSCs are dependent on CNT loading in the electrodes. A small amount of CNT clearly enhances DSSC efficiency, while excessive CNT loading significantly lowers their performance. The former is because CNT enhance the transport of electrons from the films to FTO substrates. The latter is due to high CNT loading shielding the visible light from being adsorbed by dyes.

  2. Zn-doped nanocrystalline TiO2 films for CdS quantum dot sensitized solar cells.

    PubMed

    Zhu, Guang; Cheng, Zujun; Lv, Tian; Pan, Likun; Zhao, Qingfei; Sun, Zhuo

    2010-07-01

    Quantum dot-sensitized solar cells based on Zn-doped TiO(2) (Zn-TiO(2)) film photoanode and polysulfide electrolyte were fabricated. Zn-TiO(2) nanoparticles were obtained via a hydrothermal method and screen printed on the fluorine-doped tin oxide glass to prepare the photoanode. The structure, morphology and impedance of the Zn-TiO(2)/CdS film and the photovoltaic performance of the Zn-TiO(2)/CdS cell were investigated. It was found that the photovoltaic efficiency was improved by 24% when the Zn-TiO(2) film was adopted as the photoanode of CdS QDSSCs instead of only the TiO(2) layer. The improvement was ascribed to the reduction of electron recombination and the enhancement of electron transport in the TiO(2) film by Zn doping.

  3. Electrophoretic deposited TiO2 pigment-based back reflectors for thin film solar cells

    DOE PAGES

    Bills, Braden; Morris, Nathan; Dubey, Mukul; Wang, Qi; Fan, Qi Hua

    2015-01-16

    Highly reflective coatings with strong light scattering effect have many applications in optical components and optoelectronic devices. This paper reports titanium dioxide (TiO2) pigment-based reflectors that have 2.5 times higher broadband diffuse reflection than commercially produced aluminum or silver based reflectors and result in efficiency enhancements of a single-junction amorphous Si solar cell. Electrophoretic deposition is used to produce pigment-based back reflectors with high pigment density, controllable film thickness and site-specific deposition. Electrical conductivity of the pigment-based back reflectors is improved by creating electrical vias throughout the pigment-based back reflector by making holes using an electrical discharge / dielectric breakdownmore » approach followed by a second electrophoretic deposition of conductive nanoparticles into the holes. While previous studies have demonstrated the use of pigment-based back reflectors, for example white paint, on glass superstrate configured thin film Si solar cells, this work presents a scheme for producing pigment-based reflectors on complex shape and flexible substrates. Finally, mechanical durability and scalability are demonstrated on a continuous electrophoretic deposition roll-to-roll system which has flexible metal substrate capability of 4 inch wide and 300 feet long.« less

  4. TiO2 nanocrystals coated rutile nanorod microspheres as the scattering layers for dye-sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Gao, Mengyu; Wang, Hongzhi; Li, Yaogang; Zhang, Qinghong

    2013-12-01

    Anatase TiO2 nanocrystals were deposited on the rutile TiO2 nanorod microspheres (NCRNMs) via the controlled hydrolysis and condensation of titanium (IV) bis(ammonium lactato) dihydroxide (TALH) in the presence of polyethyleneimine (PEI). The anatase TiO2 nanocrystals prevented the growth of rutile TiO2 nanorod microspheres from sintering process. By coating of anatase nanocrystals, the decreasing of specific surface area of rutile TiO2 nanorod microspheres (RNMs) were efficiently inhibited. The specific surface area of NCRNM was 47.0 m2/g after sintering at 500 °C,which was 50% increment compared to RNM. The dye sensitized solar cells (DSSCs) were assembled using the semitransparent underlayers and NCRNM scattering layers as the photoanodes. The incident photon to current conversion efficiency (IPCE) analysis showed the DSSCs in the presence of NCRNMs adsorbed more dye molecules while kept a high light-harvesting efficiency. The cell covered with the NCRNM scattering layer had the efficiency of 7.33%, which was 20% increment compared to that of the absence one.

  5. Improvement in performance of dye-sensitized solar cells with porous TiO2 electrodes using squid ink particles

    NASA Astrophysics Data System (ADS)

    Matsuura, Toshihiko; Nagai, Sakura; Ogasawara, Kou; Minato, Ken-ichi; Sakai, Mitsuo; Ueno, Takashi

    2016-06-01

    A potentially appealing alternative to the traditional fabrication process of TiO2 film electrodes for dye-sensitized solar cells (DSSCs) was presented by utilizing water-soluble TiO2 composite pastes containing size-controlled ink particles (SIPs) isolated from the squid. The mixture ratios of SIPs in the paste formulations affected the photoelectric conversion efficiency (PCE). The highest PCE was achieved when the mixture ratio of SIPs was 20%. The process is highly reproducible and leads to a 35% increase in PCE compared with that in the DSSC without SIP addition. The utilization of SIPs in the fabrication of TiO2 film electrodes enhanced the performance of DSSCs.

  6. Revealing the Origin of Fast Electron Transfer in TiO2-Based Dye-Sensitized Solar Cells.

    PubMed

    Wei, Hai; Luo, Jun-Wei; Li, Shu-Shen; Wang, Lin-Wang

    2016-07-01

    In dye-sensitized solar cells (DSCs), the electron transfer from photoexcited dye molecules to semiconductor substrates remains a major bottleneck. Replacing TiO2 with ZnO is expected to enhance the efficiency of DSCs, owing to the latter possesses a much larger electron mobility, but similar bandgap and band positions as TiO2 remain. However, the record efficiency of ZnO-based DSCs is only 7% compared with 13% of TiO2-based DSCs due to the even slower electron-transfer rate in ZnO-based DSCs, which becomes a long-standing puzzle. Here, we computationally investigate the electron transfer from the dye molecule into ZnO and TiO2, respectively, by performing the first-principles calculations within the frame of the Marcus theory. The predicted electron-transfer rate in the TiO2-based DSC is about 1.15 × 10(9) s(-1), a factor of 15 faster than that of the ZnO-based DSC, which is in good agreement with experimental data. We find that the much larger density of states of the TiO2 compared with ZnO near the conduction band edge is the dominant factor, which is responsible for the faster electron-transfer rate in TiO2-based DSCs. These denser states provide additional efficient channels for the electron transfer. We also provide design principles to boost the efficiency of DSCs through surface engineering of high mobility photoanode semiconductors.

  7. Preparation of highly porous TiO2 nanofibers for dye-sensitized solar cells (DSSCs) by electro-spinning

    NASA Astrophysics Data System (ADS)

    Jung, Won Ho; Kwak, Noh-Seok; Hwang, Taek Sung; Yi, Kwang Bok

    2012-11-01

    TiO2 nanofibers for use in dye-sensitized solar cells (DSSCs) were prepared from a solution of polymerized titanium tetraisopropoxide using a modified electro-spinning process to create fibers with high specific surface areas. The sol-gel technique was utilized to prepare the spinning solution, and glycerin was added to investigate its effects on the surface area and porosity of the TiO2 nanofibers. The spinning rate, tip-to-collector distance, voltage, and amount of glycerin were varied simultaneously and independently to determine the optimal conditions for the preparation of highly porous TiO2 nanofibers. The optimal conditions for producing such electrospun TiO2 nanofibers were 0.4 g of glycerin per 29 ml of spinning solution, an applied voltage of 22 kV, a flow rate of 0.1 ml/h, and a tip-to-collector distance (TCD) of 20 cm. The thermal decomposition of glycerin during the calcination process increased the surface area of the finished TiO2 nanofibers. SEM and XRD analyses confirmed that the TiO2 nanofibers had an anatase crystallite structure and possessed thicknesses of 80-150 nm, a maximum specific surface area of 103.3 m2/g, maximum porosity of 80.5% and maximum efficiency of 4.6%, which was significantly higher than that of typical TiO2 nanofibers. Thermogravimetric analysis revealed that the solvent, binder, and impurities were removed at 100 °C, 250 °C and 450 °C, respectively.

  8. Revealing the Origin of Fast Electron Transfer in TiO2-Based Dye-Sensitized Solar Cells.

    PubMed

    Wei, Hai; Luo, Jun-Wei; Li, Shu-Shen; Wang, Lin-Wang

    2016-07-01

    In dye-sensitized solar cells (DSCs), the electron transfer from photoexcited dye molecules to semiconductor substrates remains a major bottleneck. Replacing TiO2 with ZnO is expected to enhance the efficiency of DSCs, owing to the latter possesses a much larger electron mobility, but similar bandgap and band positions as TiO2 remain. However, the record efficiency of ZnO-based DSCs is only 7% compared with 13% of TiO2-based DSCs due to the even slower electron-transfer rate in ZnO-based DSCs, which becomes a long-standing puzzle. Here, we computationally investigate the electron transfer from the dye molecule into ZnO and TiO2, respectively, by performing the first-principles calculations within the frame of the Marcus theory. The predicted electron-transfer rate in the TiO2-based DSC is about 1.15 × 10(9) s(-1), a factor of 15 faster than that of the ZnO-based DSC, which is in good agreement with experimental data. We find that the much larger density of states of the TiO2 compared with ZnO near the conduction band edge is the dominant factor, which is responsible for the faster electron-transfer rate in TiO2-based DSCs. These denser states provide additional efficient channels for the electron transfer. We also provide design principles to boost the efficiency of DSCs through surface engineering of high mobility photoanode semiconductors. PMID:27282781

  9. Shell-in-Shell TiO2 hollow microspheres and optimized application in light-trapping perovskite solar cells

    NASA Astrophysics Data System (ADS)

    Sun, Hongxia; Ruan, Peng; Bao, Zhongqiu; Chen, Lei; Zhou, Xingfu

    2015-02-01

    The shell-in-shell structured TiO2 hollow microspheres with enhanced light scattering ability were synthesized via a facile one step hydrothermal process. The diameter of the microsphere is about 1.5 μm, the core of the unique shell-in-shell structure is composed of TiO2 nanoparticles with a diameter of about 15 nm, while the shell is constructed with ∼50 nm TiO2 nanocubes. The hollow space between the outer shell and the inner shell is about 230 nm. The formation mechanism of the unique shell-in-shell structure is interpreted. The design and the optimized application of shell-in-shell structured TiO2 hollow microspheres in the light-trapping perovskite solar cells are also investigated. Owing to the light scattering properties of the shell-in-shell structure of the hollow microsphere, the optimized photoelectrode exhibits an enhanced photoelectric conversion efficiency of 4.29% using perovskite CH3NH3PbI3 as the sensitizer. The shell-in-shell hollow TiO2 microsphere shows a 21.2% increase in conversion efficiency when compared with P25 nanoparticels photoanode. The conversion efficiency enhancement is mainly attributed to the increase of short-current density induced by the light scattering effect.

  10. Defective TiO2 with high photoconductive gain for efficient and stable planar heterojunction perovskite solar cells.

    PubMed

    Li, Yanbo; Cooper, Jason K; Liu, Wenjun; Sutter-Fella, Carolin M; Amani, Matin; Beeman, Jeffrey W; Javey, Ali; Ager, Joel W; Liu, Yi; Toma, Francesca M; Sharp, Ian D

    2016-01-01

    Formation of planar heterojunction perovskite solar cells exhibiting both high efficiency and stability under continuous operation remains a challenge. Here, we show this can be achieved by using a defective TiO2 thin film as the electron transport layer. TiO2 layers with native defects are deposited by electron beam evaporation in an oxygen-deficient environment. Deep-level hole traps are introduced in the TiO2 layers and contribute to a high photoconductive gain and reduced photocatalytic activity. The high photoconductivity of the TiO2 electron transport layer leads to improved efficiency for the fabricated planar devices. A maximum power conversion efficiency of 19.0% and an average PCE of 17.5% are achieved. In addition, the reduced photocatalytic activity of the TiO2 layer leads to enhanced long-term stability for the planar devices. Under continuous operation near the maximum power point, an efficiency of over 15.4% is demonstrated for 100 h.

  11. Defective TiO2 with high photoconductive gain for efficient and stable planar heterojunction perovskite solar cells

    PubMed Central

    Li, Yanbo; Cooper, Jason K.; Liu, Wenjun; Sutter-Fella, Carolin M.; Amani, Matin; Beeman, Jeffrey W.; Javey, Ali; Ager, Joel W.; Liu, Yi; Toma, Francesca M.; Sharp, Ian D.

    2016-01-01

    Formation of planar heterojunction perovskite solar cells exhibiting both high efficiency and stability under continuous operation remains a challenge. Here, we show this can be achieved by using a defective TiO2 thin film as the electron transport layer. TiO2 layers with native defects are deposited by electron beam evaporation in an oxygen-deficient environment. Deep-level hole traps are introduced in the TiO2 layers and contribute to a high photoconductive gain and reduced photocatalytic activity. The high photoconductivity of the TiO2 electron transport layer leads to improved efficiency for the fabricated planar devices. A maximum power conversion efficiency of 19.0% and an average PCE of 17.5% are achieved. In addition, the reduced photocatalytic activity of the TiO2 layer leads to enhanced long-term stability for the planar devices. Under continuous operation near the maximum power point, an efficiency of over 15.4% is demonstrated for 100 h. PMID:27534585

  12. Effect of TiO2 Particle Size on the Performance of Flexible Dye Sensitized Solar Cells.

    PubMed

    Li, Zhen-yu; Akhtar, M Shaheer; Yang, O-bong

    2015-09-01

    The size TiO2 nanoparticles was controlled by changing the concentration of titanium tetraisopropanolate (TTIP) and utilized as light scattering particles in the efficient flexible photoelectrodes for flexible dye sensitized solar cells (DSSCs). The flexible photoelectrodes were prepared by TiO2 nanoparticles (-25 nm) paste with different concentrations of ethanolic TTIP solution. The addition of TTIP produced the bigger TiO2 nanoparticles, which significantly enhanced the dye absorption of flexible TiO2 photoelectrode. The fabricated flexible DSSCs showed the reasonable conversion efficiency of 2.50% with short circuit current (J(sc)) of 6.3 mA/cm2, open circuit voltage (V(oc)) of 0.720 V and fill factor (FF) of 0.55. The improvement in photovoltaic performance with 25 wt% TTIP might due to uniform distribution of small TiO2 nanoparticles over the big particles to lead the enhancement in the surface area, resulting in the high dye absorption and light harvesting efficiency. PMID:26716227

  13. Sugar apple-shaped TiO2 hierarchical spheres for highly efficient dye-sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Lei, Bing-Xin; Zeng, Li-Li; Zhang, Ping; Qiao, He-Kang; Sun, Zhen-Fan

    2014-05-01

    The sugar apple-shaped TiO2 hierarchical spheres are prepared by a facile hydrothermal method using polyethylene glycol 600 as stabilized reagent, (NH4)2TiF6 and urea as starting materials at 180 °C. The characterizations show that the TiO2 hierarchical sphere has well-defined pyramid-shaped crystal facets. The as-prepared TiO2 hierarchical spheres are crystalline of the anatase phase, with a diameter of about 2-4 μm and a surface area of 36.846 m2 g-1. The optical investigation evidences that the sugar apple-shaped TiO2 hierarchical sphere film exhibits a prominent light scattering effect at a wavelength range of 600-800 nm due to the unique hierarchical morphology. Furthermore, the sugar apple-shaped TiO2 hierarchical spheres are deposited as the scattering layer to balance the dye adsorption and light scattering effect in DSSCs and a 7.20% solar energy conversion efficiency is demonstrated, indicating an improvement compared with the P25 cell (6.68%). Based on the optical and electrochemical investigations, the high conversion efficiency is mainly due to the effective suppression of the back reaction of the injected electron with the I3- in the electrolyte and excellent light scattering ability.

  14. Defective TiO2 with high photoconductive gain for efficient and stable planar heterojunction perovskite solar cells

    NASA Astrophysics Data System (ADS)

    Li, Yanbo; Cooper, Jason K.; Liu, Wenjun; Sutter-Fella, Carolin M.; Amani, Matin; Beeman, Jeffrey W.; Javey, Ali; Ager, Joel W.; Liu, Yi; Toma, Francesca M.; Sharp, Ian D.

    2016-08-01

    Formation of planar heterojunction perovskite solar cells exhibiting both high efficiency and stability under continuous operation remains a challenge. Here, we show this can be achieved by using a defective TiO2 thin film as the electron transport layer. TiO2 layers with native defects are deposited by electron beam evaporation in an oxygen-deficient environment. Deep-level hole traps are introduced in the TiO2 layers and contribute to a high photoconductive gain and reduced photocatalytic activity. The high photoconductivity of the TiO2 electron transport layer leads to improved efficiency for the fabricated planar devices. A maximum power conversion efficiency of 19.0% and an average PCE of 17.5% are achieved. In addition, the reduced photocatalytic activity of the TiO2 layer leads to enhanced long-term stability for the planar devices. Under continuous operation near the maximum power point, an efficiency of over 15.4% is demonstrated for 100 h.

  15. Controllable preparation of TiO2 nanowire arrays on titanium mesh for flexible dye-sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Liu, Wenwu; Lu, Hui; Zhang, Mei; Guo, Min

    2015-08-01

    TiO2 nanowire arrays (NWAs) with an average diameter of 80 nm have been successfully synthesized on titanium (Ti) mesh substrates via hydrothermal method. The effects of preparing conditions such as concentration of NaOH solution, reaction time, and hydrothermal temperature on the growth of TiO2 nanoarrays and its related photovoltaic properties were systematically investigated by scanning electron microscopy, X-ray diffraction, and photovoltaic properties test. The growth mechanism of the Ti mesh-supported TiO2 nanostructures was discussed in detail. Moreover, a parametric study was performed to determine the optimized temperature and time of the dye sensitized process for the flexible dye-sensitized solar cell (DSSC). It is demonstrated that hydrothermal parameters had obvious influence on the morphology and growth density of the as-prepared TiO2 nanoarrays. In addition, the performance of the flexible DSSC depended strongly on the sensitization temperature and time. By utilizing Ti mesh-supported TiO2 NWAs (with a length of about 14 μm) as a photoanode, the flexible DSSC with a short circuit current density of 10.49 mA cm-2, an open-circuit voltage of 0.69 V, and an overall power conversion efficiency of 3.42% was achieved.

  16. Defective TiO2 with high photoconductive gain for efficient and stable planar heterojunction perovskite solar cells.

    PubMed

    Li, Yanbo; Cooper, Jason K; Liu, Wenjun; Sutter-Fella, Carolin M; Amani, Matin; Beeman, Jeffrey W; Javey, Ali; Ager, Joel W; Liu, Yi; Toma, Francesca M; Sharp, Ian D

    2016-01-01

    Formation of planar heterojunction perovskite solar cells exhibiting both high efficiency and stability under continuous operation remains a challenge. Here, we show this can be achieved by using a defective TiO2 thin film as the electron transport layer. TiO2 layers with native defects are deposited by electron beam evaporation in an oxygen-deficient environment. Deep-level hole traps are introduced in the TiO2 layers and contribute to a high photoconductive gain and reduced photocatalytic activity. The high photoconductivity of the TiO2 electron transport layer leads to improved efficiency for the fabricated planar devices. A maximum power conversion efficiency of 19.0% and an average PCE of 17.5% are achieved. In addition, the reduced photocatalytic activity of the TiO2 layer leads to enhanced long-term stability for the planar devices. Under continuous operation near the maximum power point, an efficiency of over 15.4% is demonstrated for 100 h. PMID:27534585

  17. Photovoltaic performance of nanoporous TiO2 replicas synthesized from mesoporous materials for dye-sensitized solar cells.

    PubMed

    Hwang, Kyung-Jun; Yoo, Seung-Joon; Kim, Sung-Soo; Kim, Ji-Man; Shim, Wang-Geun; Kim, Sun-Il; Lee, Jae-Wook

    2008-10-01

    For dye-sensitized solar cell (DSSC), highly ordered nanoporous TiO2 materials with crystalline frameworks were successfully synthesized from different silica templates including SBA-15, KIT-6 and MSU-H. A photoelectrode in DSSC was fabricated by adsorbing cis-bis(isothiocyanato)bis(2,2'-bipyridyl-4,4'-dicarboxylato)-ruthenium(II)bis-tetrabutylammonium dye (N719) onto the prepared TiO2 nanoparticles. The samples were characterized by XRD, TEM, FE-SEM, AFM and Brunauer-Emmett-Teller (BET), and FT-IR analysis. An investigation of the influence of the bonding structure of N719 dye and nanoporous TiO2 on the photovoltaic performance of DSSC revealed that the bonding structure of N719 on TiO2 films is caused by the unidentate and bidentate linkage. Based on the overall conversion efficiency (eta), fill factor (FF), open-circuit voltage (V(oc)) and short-circuit current (/sc) from the I-V curves measured, it was observed that the photoelectric performance is strongly dependent on the dispersion properties of the nanoporous TiO2 replicas from mesoporous silica templates.

  18. Photovoltaic study of dye sensitized solar cells based on TiO2, ZnO:Al3+ nanoparticles

    NASA Astrophysics Data System (ADS)

    Sánchez Godoy, H. E.; Rodríguez-Rojas, R. A.; Castañeda-Contreras, J.; Marañón-Ruiz, V. F.; Pérez-Ladrón de Guevara, H.; López-Luke, T.; De la Rosa-Cruz

    2015-10-01

    A technique to fabricate dye (rhodamine B) sensitized solar cells based on Titanium Oxide (TiO2) and Zinc Oxide (ZnO) nanoparticles are reported. The TiO2 was synthesized using the sol-gel method and the ZnO was synthesized by hydrolysis method to obtain nanoparticles of ~ 5 nm and 150 nm respectively. ZnO was doped with Al3+ in order to enhance the photovoltaic efficiency to promote the electrons mobility. The photovoltaic conversion characterization of films of TiO2, ZnO and ZnO:Al3+ nanoparticles is also reported. The generated photocurrent was measured by two methods; one of those uses a three electrode electrochemical cell and the other use an electronic array where the cells were exposed to UV lamp and the sun light. The role of the TiO2, ZnO and Al3+ doped ZnO nanoparticles is discussed to obtain a better efficiency in the generation of photocurrent (PC). The results exhibited by the electrochemical cell method, efficiencies of 0.55 (PC=187 μA/cm2) and 0.22 (PC=149 μA/cm2) for TiO2 and undoped ZnO respectively. However, when ZnO is doped with Al3+ at the higher concentration the efficiency was 0.44. While using the electronic array the results exhibited efficiencies of 0.31 (PC=45 μA/cm2) and 0.09 (PC=16 μA/cm2) for TiO2 and undoped ZnO respectively. However, when ZnO is doped with Al3+ at the higher concentration the efficiency was 0.44 and 0.48 for electrochemical cell and electronic array respectively. This shows that Al3+ enhances the photogenerated charge carriers increasing the mobility of electrons.

  19. TiO2 nanotube membranes on transparent conducting glass for high efficiency dye-sensitized solar cells.

    PubMed

    Dubey, Mukul; Shrestha, Maheshwar; Zhong, Yihan; Galipeau, David; He, Hongshan

    2011-07-15

    Crack-free TiO(2) nanotube (NT) membranes were obtained by short time re-anodization of a sintered TiO(2) NT array on Ti foil, followed by dilute HF etching at room temperature. The resulting freestanding TiO(2) membranes were opaque with a slight yellow color having one end open and another end closed. The membranes were then fixed on transparent fluorine-tin-oxide glass using a thin layer of screen-printed TiO(2) nanoparticles (NPs) as a binding medium. It was found that low temperature treatment of the resulting NT/NP film under appropriate pressure before sintering at 450 °C was critical for successful fixation of the NT membrane on the NP layer. The resulting films with open-ends of NT membranes facing the NP layer (open-ends down, OED, configuration) exhibited better interfacial contact between NTs and NPs than those with closed-ends facing the NP layer (closed-ends down, CED, configuration). The cells with an OED configuration exhibit higher external quantum efficiency, greater charge transfer resistance from FTO/TiO(2) to electrolyte, and better dye loading compared to CED configurations. The solar cells with the OED configuration gave 6.1% energy conversion efficiency under AM1.5G condition when the commercial N719 was used as a dye and I(-)/I(3)(-) as a redox couple, showing the promise of this method for high efficiency solar cells.

  20. The effect of light-scattering layer on the performance of dye-sensitized solar cell assembled using TiO2 double-layered films as photoanodes

    NASA Astrophysics Data System (ADS)

    Zhu, L.; Zhao, Y. L.; Lin, X. P.; Gu, X. Q.; Qiang, Y. H.

    2014-01-01

    Dye-sensitized solar cells (DSSCs) are fabricated based on double-layered films of TiO2 nanospheres and TiO2 nanorod arrays (NRAs). TiO2 nanospheres, including TiO2 hollow spheres (HSs) and TiO2 solid spheres (SSs), were served as light-scattering layers on TiO2 NRAs as composite photoanodes. The as-prepared TiO2 NRAs, TiO2 HSs and TiO2 SSs have been characterized by field emission scanning electron microscopy, transmission electron microscopy and X-ray diffraction. The photoelectric properties of DSSCs were investigated by UV-vis reflectance spectra, current-voltage curves and electrochemical impedance spectroscopy. Owing to the synergic effects of the TiO2 HSs (SSs) and NRAs, including large specific surface area of HSs (SSs) as light-scattering layer for effective dye adsorption and harvesting light and rapid electron transport in one dimensional TiO2 NRAs, the optimal energy conversion efficiency of DSSCs with as-prepared double-layered films as nanocomposite photoanode (5.40%) were far higher than the ones using single-layered NRAs films (1.56%).

  1. TiO2 nanowires for potential facile integration of solar cells and electrochromic devices.

    PubMed

    Qiang, Pengfei; Chen, Zhongwei; Yang, Peihua; Cai, Xiang; Tan, Shaozao; Liu, Pengyi; Mai, Wenjie

    2013-11-01

    Self-powered systems usually consist of energy-acquisition components, energy-storage components and functional components. The development of nanoscience and nanotechnology has greatly improved the performance of all the components of self-powered systems. However, huge differences in the materials and configurations in the components cause large difficulties for integration and miniaturization of self-powered systems. Design and fabrication of different components in a self-powered system with the same or similar materials/configurations should be able to make the above goal easier. In this work, a proof-of-concept experiment involving an integrated self-powered color-changing system consisting of TiO2 nanowire based sandwich dye-sensitized solar cells (DSSCs) and electrochromic devices (ECDs) is designed and demonstrated. When sunlight illuminates the entire system, the DSSCs generate electrical power and turn the ECD to a darker color, dimming the light; by switching the connection polarity of the DSSCs, the lighter color can be regained, implying the potential application of this self-powered color-changing system for next generation sun glasses and smart windows. PMID:24107414

  2. TiO2 nanowires for potential facile integration of solar cells and electrochromic devices.

    PubMed

    Qiang, Pengfei; Chen, Zhongwei; Yang, Peihua; Cai, Xiang; Tan, Shaozao; Liu, Pengyi; Mai, Wenjie

    2013-11-01

    Self-powered systems usually consist of energy-acquisition components, energy-storage components and functional components. The development of nanoscience and nanotechnology has greatly improved the performance of all the components of self-powered systems. However, huge differences in the materials and configurations in the components cause large difficulties for integration and miniaturization of self-powered systems. Design and fabrication of different components in a self-powered system with the same or similar materials/configurations should be able to make the above goal easier. In this work, a proof-of-concept experiment involving an integrated self-powered color-changing system consisting of TiO2 nanowire based sandwich dye-sensitized solar cells (DSSCs) and electrochromic devices (ECDs) is designed and demonstrated. When sunlight illuminates the entire system, the DSSCs generate electrical power and turn the ECD to a darker color, dimming the light; by switching the connection polarity of the DSSCs, the lighter color can be regained, implying the potential application of this self-powered color-changing system for next generation sun glasses and smart windows.

  3. TiO2 nanowires for potential facile integration of solar cells and electrochromic devices

    NASA Astrophysics Data System (ADS)

    Qiang, Pengfei; Chen, Zhongwei; Yang, Peihua; Cai, Xiang; Tan, Shaozao; Liu, Pengyi; Mai, Wenjie

    2013-11-01

    Self-powered systems usually consist of energy-acquisition components, energy-storage components and functional components. The development of nanoscience and nanotechnology has greatly improved the performance of all the components of self-powered systems. However, huge differences in the materials and configurations in the components cause large difficulties for integration and miniaturization of self-powered systems. Design and fabrication of different components in a self-powered system with the same or similar materials/configurations should be able to make the above goal easier. In this work, a proof-of-concept experiment involving an integrated self-powered color-changing system consisting of TiO2 nanowire based sandwich dye-sensitized solar cells (DSSCs) and electrochromic devices (ECDs) is designed and demonstrated. When sunlight illuminates the entire system, the DSSCs generate electrical power and turn the ECD to a darker color, dimming the light; by switching the connection polarity of the DSSCs, the lighter color can be regained, implying the potential application of this self-powered color-changing system for next generation sun glasses and smart windows.

  4. Improvement of Charge Transportation in Si Quantum Dot-Sensitized Solar Cells Using Vanadium Doped TiO2.

    PubMed

    Seo, Hyunwoong; Ichida, Daiki; Hashimoto, Shinji; Itagaki, Naho; Koga, Kazunori; Shiratani, Masaharu; Nam, Sang-Hun; Boo, Jin-Hyo

    2016-05-01

    The multiple exciton generation characteristics of quantum dots have been expected to enhance the performance of photochemical solar cells. In previous work, we first introduced Si quantum dot for sensitized solar cells. The Si quantum dots were fabricated by multi-hollow discharge plasma chemical vapor deposition, and were characterized optically and morphologically. The Si quantum dot-sensitized solar cells had poor performance due to significant electron loss by charge recombination. Although the large Si particle size resulted in the exposure of a large TiO2 surface area, there was a limit to ho much the particle size could be decreased due to the reduced absorbance of small particles. Therefore, this work focused on decreasing the internal impedance to improve charge transfer. TiO2 was electronically modified by doping with vanadium, which can improve electron transfer in the TiO2 network, and which is stable in the redox electrolyte. Photogenerated electrons can more easily arrive at the conductive electrode due to the decreased internal impedance. The dark photovoltaic properties confirmed the reduction of charge recombination, and the photon-to-current conversion efficiency reflected the improved electron transfer. Impedance analysis confirmed a decrease in internal impedance and an increased electron lifetime. Consequently, these improvements by vanadium doping enhanced the overall performance of Si quantum dot-sensitized solar cells. PMID:27483838

  5. Effect of TiO2 rutile nanorods on the photoelectrodes of dye-sensitized solar cells

    PubMed Central

    2013-01-01

    In order to enhance the electron transport on the photoelectrodes of dye-sensitized solar cells, one-dimensional rutile nanorods were prepared using electrospun TiO2 nanofibers. The grain size of the nanorods increased with increasing temperature. Electrochemical impedance spectroscopy measurements revealed reduced interface resistance of the cells with the one-dimensional rutile nanorods due to the improved electron transport and the enhanced electrolyte penetration. Intensity-modulated photocurrent/photovoltage spectroscopy showed that the one-dimensional rutile nanorods provided the electrons with a moving pathway and suppressed the recombination of photogenerated electrons. However, an excessive quantity of rutile nanorods created an obstacle to the electrons moving in the TiO2 thin film. The photoelectrode with 7 wt.% rutile nanorods optimized the performance of the dye-sensitized solar cells. PMID:23331863

  6. Characterization of screen-printed dye-sensitized nanocrystalline TiO2 solar cells

    NASA Astrophysics Data System (ADS)

    Gupta, Tapan K.; Cirignano, Leonard J.; Shah, Kanai S.; Moy, Larry P.; Kelly, David J.; Squillante, Michael R.; Entine, Gerald; Smestad, Greg P.

    1999-10-01

    Titanium dioxide (TiO2) films have been deposited on SnO2 coated glass substrates by screen-printing. Film morphology and structure have been characterized by scanning electron microscopy, x-ray diffraction and BET analysis. Dye-sensitized TiO2 photoelectrochemical cells have been assembled and characterized. Cells sensitized with anthocyanin and a ruthenium complex have been investigated. A 0.77 cm2 ruthenium dye sensitized cell with 6.1% power conversion efficiency under Air Mass (AM1.5) conditions was obtained. Results obtained with a pure anthocyanin dye and dye extracted from blackberries were compared. Finally, a natural gel was found to improve the stability of anthocyanin sensitized cells.

  7. Niobium Doping Effects on TiO2 Mesoscopic Electron Transport Layer-Based Perovskite Solar Cells.

    PubMed

    Kim, Dong Hoe; Han, Gill Sang; Seong, Won Mo; Lee, Jin-Wook; Kim, Byeong Jo; Park, Nam-Gyu; Hong, Kug Sun; Lee, Sangwook; Jung, Hyun Suk

    2015-07-20

    Perovskite solar cells (PSCs) are the most promising candidates as next-generation solar energy conversion systems. To design a highly efficient PSC, understanding electronic properties of mesoporous metal oxides is essential. Herein, we explore the effect of Nb doping of TiO2 on electronic structure and photovoltaic properties of PSCs. Light Nb doping (0.5 and 1.0 at %) increased the optical band gap slightly, but heavy doping (5.0 at %) distinctively decreased it. The relative Fermi level position of the conduction band is similar for the lightly Nb-doped TiO2 (NTO) and the undoped TiO2 whereas that of the heavy doped NTO decreased by as much as ∼0.3 eV. The lightly doped NTO-based PSCs exhibit 10 % higher efficiency than PSCs based on undoped TiO2 (from 12.2 % to 13.4 %) and 52 % higher than the PSCs utilizing heavy doped NTO (from 8.8 % to 13.4 %), which is attributed to fast electron injection/transport and preserved electron lifetime, verified by transient photocurrent decay and impedance studies.

  8. N719- and D149-sensitized 3D hierarchical rutile TiO2 solar cells--a comparative study.

    PubMed

    Lin, Jianjian; Heo, Yoon-Uk; Nattestad, Andrew; Shahabuddin, Mohammed; Yamauchi, Yusuke; Kim, Jung Ho

    2015-03-21

    Poor dye loading on rutile TiO2 is one of the chief reasons for lower solar-to-electric conversion efficiency (η) in dye-sensitized solar cells (DSCs), compared to their anatase based counterparts. Previously, we showed that similar light harvesting for both rutile and anatase was realized by using a metal-free organic indoline dye, D149 [Sci. Rep., 2014, 4, 5769]. This was in contrast to the bulk of previous studies, which employed ruthenium based N719, leading to significant differences in light harvesting. To date, there has been no report directly comparing N719 and D149 for rutile based DSCs. In this work, three-dimensional hierarchical rutile TiO2 architecture (HRTA), consisting of one-dimensional nanorods, was successfully prepared via a facile hydrothermal method, and subsequently optimized as effective photoelectrodes for DSCs. Two dyes, N719 and D149, were used as sensitizers of the HRTA-based DSCs, with maximum η of 5.6% and 5.8% achieved, respectively. The higher η of the D149-sensitized DSC is ascribed to its higher extinction co-efficient, allowing a greater amount of light to be harvested with a thinner TiO2 layer. This study suggests that some of the limitations typically observed for rutile TiO2 based DSCs can be overcome through the use of strongly absorbing metal-free organic sensitizers. Furthermore, it reemphasises the importance of viewing DSCs as whole systems, rather than individual components.

  9. Reduced interfacial recombination in dye-sensitized solar cells assisted with NiO:Eu(3+),Tb(3+) coated TiO2 film.

    PubMed

    Yao, Nannan; Huang, Jinzhao; Fu, Ke; Deng, Xiaolong; Ding, Meng; Zhang, Shouwei; Xu, Xijin; Li, Lin

    2016-01-01

    Eu(3+),Tb(3+) doped and undoped NiO films were deposited on TiO2 by a sol-gel spin-coating method as the photoanodes of dye sensitized solar cells (DSSCs). A comparative study with different structures including TiO2, TiO2/NiO and TiO2/NiO:Eu(3+),Tb(3+) as the photoanodes was carried out to illustrate the photovoltaic performance of solar cells. NiO could enhance the performance of DSSCs ascribed to acting as a barrier for the charge recombination from the fluorine doped tin oxide (FTO) to electrolyte and forming a p-n junction (NiO/TiO2). Moreover, Eu(3+), Tb(3+) co-doped NiO could accelerate the electron transfer at TiO2/dye/electrolyte interface, which further benefited the performance of solar cells. The solar cells assembled with the photoelectrodes consisting of NiO:Eu(3+),Tb(3+) and TiO2 exhibited short-circuit current density (JSC) of 17.4 mA cm(-2), open-circuit voltage (VOC) of 780 mV and conversion efficiency of 8.8%, which were higher than that with TiO2/NiO and pure TiO2. The mechanisms of the influence of NiO and NiO:Eu(3+),Tb(3+) on the photovoltaic performance of DSSCs were discussed. PMID:27506930

  10. Reduced interfacial recombination in dye-sensitized solar cells assisted with NiO:Eu3+,Tb3+ coated TiO2 film

    PubMed Central

    Yao, Nannan; Huang, Jinzhao; Fu, Ke; Deng, Xiaolong; Ding, Meng; Zhang, Shouwei; Xu, Xijin; Li, Lin

    2016-01-01

    Eu3+,Tb3+ doped and undoped NiO films were deposited on TiO2 by a sol-gel spin-coating method as the photoanodes of dye sensitized solar cells (DSSCs). A comparative study with different structures including TiO2, TiO2/NiO and TiO2/NiO:Eu3+,Tb3+ as the photoanodes was carried out to illustrate the photovoltaic performance of solar cells. NiO could enhance the performance of DSSCs ascribed to acting as a barrier for the charge recombination from the fluorine doped tin oxide (FTO) to electrolyte and forming a p-n junction (NiO/TiO2). Moreover, Eu3+, Tb3+ co-doped NiO could accelerate the electron transfer at TiO2/dye/electrolyte interface, which further benefited the performance of solar cells. The solar cells assembled with the photoelectrodes consisting of NiO:Eu3+,Tb3+ and TiO2 exhibited short-circuit current density (JSC) of 17.4 mA cm−2, open-circuit voltage (VOC) of 780 mV and conversion efficiency of 8.8%, which were higher than that with TiO2/NiO and pure TiO2. The mechanisms of the influence of NiO and NiO:Eu3+,Tb3+ on the photovoltaic performance of DSSCs were discussed. PMID:27506930

  11. Reduced interfacial recombination in dye-sensitized solar cells assisted with NiO:Eu3+,Tb3+ coated TiO2 film

    NASA Astrophysics Data System (ADS)

    Yao, Nannan; Huang, Jinzhao; Fu, Ke; Deng, Xiaolong; Ding, Meng; Zhang, Shouwei; Xu, Xijin; Li, Lin

    2016-08-01

    Eu3+,Tb3+ doped and undoped NiO films were deposited on TiO2 by a sol-gel spin-coating method as the photoanodes of dye sensitized solar cells (DSSCs). A comparative study with different structures including TiO2, TiO2/NiO and TiO2/NiO:Eu3+,Tb3+ as the photoanodes was carried out to illustrate the photovoltaic performance of solar cells. NiO could enhance the performance of DSSCs ascribed to acting as a barrier for the charge recombination from the fluorine doped tin oxide (FTO) to electrolyte and forming a p-n junction (NiO/TiO2). Moreover, Eu3+, Tb3+ co-doped NiO could accelerate the electron transfer at TiO2/dye/electrolyte interface, which further benefited the performance of solar cells. The solar cells assembled with the photoelectrodes consisting of NiO:Eu3+,Tb3+ and TiO2 exhibited short-circuit current density (JSC) of 17.4 mA cm‑2, open-circuit voltage (VOC) of 780 mV and conversion efficiency of 8.8%, which were higher than that with TiO2/NiO and pure TiO2. The mechanisms of the influence of NiO and NiO:Eu3+,Tb3+ on the photovoltaic performance of DSSCs were discussed.

  12. Enhanced electronic properties in mesoporous TiO2 via lithium doping for high-efficiency perovskite solar cells

    NASA Astrophysics Data System (ADS)

    Giordano, Fabrizio; Abate, Antonio; Correa Baena, Juan Pablo; Saliba, Michael; Matsui, Taisuke; Im, Sang Hyuk; Zakeeruddin, Shaik M.; Nazeeruddin, Mohammad Khaja; Hagfeldt, Anders; Graetzel, Michael

    2016-01-01

    Perovskite solar cells are one of the most promising photovoltaic technologies with their extraordinary progress in efficiency and the simple processes required to produce them. However, the frequent presence of a pronounced hysteresis in the current voltage characteristic of these devices arises concerns on the intrinsic stability of organo-metal halides, challenging the reliability of technology itself. Here, we show that n-doping of mesoporous TiO2 is accomplished by facile post treatment of the films with lithium salts. We demonstrate that the Li-doped TiO2 electrodes exhibit superior electronic properties, by reducing electronic trap states enabling faster electron transport. Perovskite solar cells prepared using the Li-doped films as scaffold to host the CH3NH3PbI3 light harvester produce substantially higher performances compared with undoped electrodes, improving the power conversion efficiency from 17 to over 19% with negligible hysteretic behaviour (lower than 0.3%).

  13. Enhanced electronic properties in mesoporous TiO2 via lithium doping for high-efficiency perovskite solar cells.

    PubMed

    Giordano, Fabrizio; Abate, Antonio; Correa Baena, Juan Pablo; Saliba, Michael; Matsui, Taisuke; Im, Sang Hyuk; Zakeeruddin, Shaik M; Nazeeruddin, Mohammad Khaja; Hagfeldt, Anders; Graetzel, Michael

    2016-01-01

    Perovskite solar cells are one of the most promising photovoltaic technologies with their extraordinary progress in efficiency and the simple processes required to produce them. However, the frequent presence of a pronounced hysteresis in the current voltage characteristic of these devices arises concerns on the intrinsic stability of organo-metal halides, challenging the reliability of technology itself. Here, we show that n-doping of mesoporous TiO2 is accomplished by facile post treatment of the films with lithium salts. We demonstrate that the Li-doped TiO2 electrodes exhibit superior electronic properties, by reducing electronic trap states enabling faster electron transport. Perovskite solar cells prepared using the Li-doped films as scaffold to host the CH3NH3PbI3 light harvester produce substantially higher performances compared with undoped electrodes, improving the power conversion efficiency from 17 to over 19% with negligible hysteretic behaviour (lower than 0.3%). PMID:26758549

  14. Enhanced electronic properties in mesoporous TiO2 via lithium doping for high-efficiency perovskite solar cells

    PubMed Central

    Giordano, Fabrizio; Abate, Antonio; Correa Baena, Juan Pablo; Saliba, Michael; Matsui, Taisuke; Im, Sang Hyuk; Zakeeruddin, Shaik M.; Nazeeruddin, Mohammad Khaja; Hagfeldt, Anders; Graetzel, Michael

    2016-01-01

    Perovskite solar cells are one of the most promising photovoltaic technologies with their extraordinary progress in efficiency and the simple processes required to produce them. However, the frequent presence of a pronounced hysteresis in the current voltage characteristic of these devices arises concerns on the intrinsic stability of organo-metal halides, challenging the reliability of technology itself. Here, we show that n-doping of mesoporous TiO2 is accomplished by facile post treatment of the films with lithium salts. We demonstrate that the Li-doped TiO2 electrodes exhibit superior electronic properties, by reducing electronic trap states enabling faster electron transport. Perovskite solar cells prepared using the Li-doped films as scaffold to host the CH3NH3PbI3 light harvester produce substantially higher performances compared with undoped electrodes, improving the power conversion efficiency from 17 to over 19% with negligible hysteretic behaviour (lower than 0.3%). PMID:26758549

  15. Ag nanoparticle-deposited TiO2 nanotube arrays for electrodes of Dye-sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Kawamura, Go; Ohmi, Hayato; Tan, Wai Kian; Lockman, Zainovia; Muto, Hiroyuki; Matsuda, Atsunori

    2015-05-01

    Dye-sensitized solar cells composed of a photoanode of Ag nanoparticle (NP)-deposited TiO2 nanotube (TNT) arrays were fabricated. The TNT arrays were prepared by anodizing Ti films on fluorine-doped tin oxide (FTO)-coated glass substrates. Efficient charge transportation through the ordered nanostructure of TNT arrays should be carried out compared to conventional particulate TiO2 electrodes. However, it has been a big challenge to grow TNT arrays on FTO glass substrates with the lengths needed for sufficient light-harvesting (tens of micrometers). In this work, we deposited Ag nanoparticles (NPs) on the wall of TNT arrays to enhance light-harvesting property. Dye-sensitized solar cells with these Ag NP-deposited TNT arrays yielded a higher power conversion efficiency (2.03 %) than those without Ag NPs (1.39 %).

  16. Low thermal budget, photonic-cured compact TiO2 layers for high-efficiency perovskite solar cells

    DOE PAGES

    Das, Sanjib; Gu, Gong; Joshi, Pooran C.; Yang, Bin; Aytug, Tolga; Rouleau, Christopher M.; Geohegan, David B.; Xiao, Kai

    2016-05-25

    Rapid advances in organometallic trihalide perovskite solar cells (PSCs) have positioned them to be one of the leading next generation photovoltaic technologies. However, most of the high-performance PSCs, particularly those using compact TiO2 as an electron transport layer, require a high-temperature sintering step, which is not compatible with flexible polymer-based substrates. Considering the materials of interest for PSCs and corresponding device configurations, it is technologically imperative to fabricate high-efficiency cells at low thermal budget so that they can be realized on low-temperature plastic substrates. In this paper, we report on a new photonic curing technique that produces crystalline anatase-phase TiO2more » films on indium tin oxide-coated glass and flexible polyethylene terephthalate (PET) substrates. Finally, the planar PSCs, using photonic-cured TiO2 films, exhibit PCEs as high as 15.0% and 11.2% on glass and flexible PET substrates, respectively, comparable to the device performance of PSCs incorporating furnace annealed TiO2 films.« less

  17. Universal Features of Electron Dynamics in Solar Cells with TiO2 Contact: From Dye Solar Cells to Perovskite Solar Cells.

    PubMed

    Todinova, Anna; Idígoras, Jesús; Salado, Manuel; Kazim, Samrana; Anta, Juan A

    2015-10-01

    The electron dynamics of solar cells with mesoporous TiO2 contact is studied by electrochemical small-perturbation techniques. The study involved dye solar cells (DSC), solid-state perovskite solar cells (SSPSC), and devices where the perovskite acts as sensitizer in a liquid-junction device. Using a transport-recombination continuity equation we found that mid-frequency time constants are proper lifetimes that determine the current-voltage curve. This is not the case for the SSPSC, where a lifetime of ∼1 μs, 1 order of magnitude longer, is required to reproduce the current-voltage curve. This mismatch is attributed to the dielectric response on the mid-frequency component. Correcting for this effect, lifetimes lie on a common exponential trend with respect to open-circuit voltage. Electron transport times share a common trend line too. This universal behavior of lifetimes and transport times suggests that the main difference between the cells is the power to populate the mesoporous TiO2 contact with electrons. PMID:26704621

  18. Universal Features of Electron Dynamics in Solar Cells with TiO2 Contact: From Dye Solar Cells to Perovskite Solar Cells.

    PubMed

    Todinova, Anna; Idígoras, Jesús; Salado, Manuel; Kazim, Samrana; Anta, Juan A

    2015-10-01

    The electron dynamics of solar cells with mesoporous TiO2 contact is studied by electrochemical small-perturbation techniques. The study involved dye solar cells (DSC), solid-state perovskite solar cells (SSPSC), and devices where the perovskite acts as sensitizer in a liquid-junction device. Using a transport-recombination continuity equation we found that mid-frequency time constants are proper lifetimes that determine the current-voltage curve. This is not the case for the SSPSC, where a lifetime of ∼1 μs, 1 order of magnitude longer, is required to reproduce the current-voltage curve. This mismatch is attributed to the dielectric response on the mid-frequency component. Correcting for this effect, lifetimes lie on a common exponential trend with respect to open-circuit voltage. Electron transport times share a common trend line too. This universal behavior of lifetimes and transport times suggests that the main difference between the cells is the power to populate the mesoporous TiO2 contact with electrons.

  19. Enhanced electron transport in mesoporous TiO2 films modified by sol-gel necking for dye-sensitized solar cells.

    PubMed

    An, Sang-Yeop; Park, Jeong-Hyun; Kim, Jae-Hong; Choi, Chel-Jong; Kim, Hyunsoo; Ahn, Kwang-Soon

    2012-04-01

    Mesoporous TiO2 films modified via sol-gel necking were fabricated by dispersing Ti tetra-isopropoxide (TTIP; 8 to 16 wt% over TiO2) with TiO2 nanoparticles in isopropyl alcohol. The dye-sensitized solar cells (DSSCs) with 13 wt% TTIP-modified TiO2 film exhibited significantly improved overall energy conversion efficiency, despite having less adsorbed dye when compared with DSSCs with untreated and TiCl4 post-treated TiO2 films. The improvement can be attributed to the sol-gel necking (or interconnection) between the nanoparticles which leads to a much faster electron transport and a suppression of the recombination (or back electron transfer) between the TiO2 and electrolyte. PMID:22849132

  20. Contributions of Ag Nanowires to the Photoelectric Conversion Efficiency Enhancement of TiO2 Dye-Sensitized Solar Cells.

    PubMed

    Liu, Yunyu; She, Guangwei; Qi, Xiaopeng; Mu, Lixuan; Wang, Xuesong; Shi, Wensheng

    2015-09-01

    Ag nanowires (AgNWs) were employed in mesoporous TiO2 dye-sensitized solar cells (DSSCs) to enhance the photoelectric conversion efficiency (PCE). The possible reasons for PCE improvement, i.e., improvement in electron transport and light harvesting due to light scattering and plasmonic resonance effect of AgNWs are investigated. Electrochemical impedance spectra (EIS) study proved that addition of AgNWs can enhance the conductivity of TiO2 thin film photoanode, which is an important reason for the increase of photocurrent. Furthermore, through the comparison experiments as well as the UV-Vis absorption and IPCE characterization, contributions of the light scattering and plasmonic resonance effect to the enhancement of light harvest, and thus PCE of the DSSCs were demonstrated. It was found that fast electron transport of AgNWs played more important role for the PCE improvement than the light harvest enhancement due to light scattering and plasmonic effect. Based on these investigations, the AgNWs modified TiO2 thin film DSSCs were optimized. After integrating AgNWs into the photoanode, the photocurrent increased significantly and PCE increased -50% comparing with the pure TiO2-based DSSCs.

  1. Synthesis of SUB-10 NM TiO2 Nanowires for the Application of Dye-Sensitized Solar Cells

    NASA Astrophysics Data System (ADS)

    Liu, Jun; Liu, Zhen; Lin, Kangbao; Wei, Aixiang

    2013-04-01

    Highly oriented single-crystalline rutile TiO2 nanowires on transparent conductive fluorine-doped tin oxide (FTO) substrates are prepared by low-temperature hydrothermal method. The small lattice mismatch between FTO substrate and rutile TiO2 promote the epitaxial nucleation and growth of rutile TiO2 nanowires on FTO, with the diameter of 4-6 nm. Due to Van der waals force, the ultrafine nanowires tend to gather together, forming nanowire bundles. Using the ultrafine nanowire bundle array as the photoanode and ruthenium complex (N719) as the sensitizer, dye-sensitized solar cells (DSSCs) are assembled. The effect of the TiO2 nanowire gathering on the power conversion of the DSSCs has been investigated. Experimental result shows that the light-to-electricity conversion efficiency is increased by reducing the gathering of the nanowires through introducing toluene into reactant precursors. The DSSCs based on the bundles with smallest average width (i.e., least nanowire gathering) show the highest power conversion efficiency of 3.70%. The relatively high energy conversion efficiency is contributed to the large surface area, which enhances the adsorption of dye molecules.

  2. Contributions of Ag Nanowires to the Photoelectric Conversion Efficiency Enhancement of TiO2 Dye-Sensitized Solar Cells.

    PubMed

    Liu, Yunyu; She, Guangwei; Qi, Xiaopeng; Mu, Lixuan; Wang, Xuesong; Shi, Wensheng

    2015-09-01

    Ag nanowires (AgNWs) were employed in mesoporous TiO2 dye-sensitized solar cells (DSSCs) to enhance the photoelectric conversion efficiency (PCE). The possible reasons for PCE improvement, i.e., improvement in electron transport and light harvesting due to light scattering and plasmonic resonance effect of AgNWs are investigated. Electrochemical impedance spectra (EIS) study proved that addition of AgNWs can enhance the conductivity of TiO2 thin film photoanode, which is an important reason for the increase of photocurrent. Furthermore, through the comparison experiments as well as the UV-Vis absorption and IPCE characterization, contributions of the light scattering and plasmonic resonance effect to the enhancement of light harvest, and thus PCE of the DSSCs were demonstrated. It was found that fast electron transport of AgNWs played more important role for the PCE improvement than the light harvest enhancement due to light scattering and plasmonic effect. Based on these investigations, the AgNWs modified TiO2 thin film DSSCs were optimized. After integrating AgNWs into the photoanode, the photocurrent increased significantly and PCE increased -50% comparing with the pure TiO2-based DSSCs. PMID:26716285

  3. Bilayer hollow/spindle-like anatase TiO2 photoanode for high efficiency dye-sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Wang, Guanxi; Zhu, Xunjin; Yu, Jiaguo

    2015-03-01

    Derived from a hollow TiO2 nanoparticle (HNP) as underlayer and a TiO2 spindle (SP) as light scattering overlayer, a new bilayer single-crystalline photoanode (HNP/SP) is fabricated for dye-sensitized solar cell (DSSC) application. The prepared bilayer TiO2 photoanode and two comparative HNP/HNP and SP/SP ones are fully characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, UV-vis absorption spectroscopy and N2 adsorption-desorption isotherms. An overall photoelectric conversion efficiency of 8.65% has been achieved for HNP/SP DSSC, which is 25% higher than that of HNP/HNP DSSC, and also far superior to that of SP/SP or conventional P25 DSSC. The improved photovoltaic performance of HNP/SP DSSC is attributed to the synergic effects, i.e. the single-crystalline bilayer structure favoring for rapid interfacial electron transport, the relatively large specific surface area of HNP for effective dye adsorption, and the 1D geometry of single-crystalline TiO2 spindles for direct electron transport pathway and strong light scattering effect.

  4. Preferred Molecular Orientation of Coumarin 343 on TiO2 Surfaces: Application to Dye-Sensitized Solar Cells.

    PubMed

    McCree-Grey, Jonathan; Cole, Jacqueline M; Evans, Peter J

    2015-08-01

    The dye···TiO2 interfacial structure in working electrodes of dye-sensitized solar cells (DSCs) is known to influence its photovoltaic device performance. Despite this, direct and quantitative reports of such structure remain sparse. This case study presents the application of X-ray reflectometry to determine the preferred structural orientation and molecular packing of the organic dye, Coumarin 343, adsorbed onto amorphous TiO2. Results show that the dye molecules are, on average, tilted by 61.1° relative to the TiO2 surface, and are separated from each other by 8.2 Å. These findings emulate the molecular packing arrangement of a monolayer of Coumarin 343 within its crystal structure. This suggests that the dye adsorbs onto TiO2 in one of its lowest energy configurations; that is, dye···TiO2 self-assembly is driven more by thermodynamic rather than kinetic means. Complementary DSC device tests illustrate that this interfacial structure compromises photovoltaic performance, unless a suitably sized coadsorbant is interdispersed between the Coumarin 343 chromophores on the TiO2 surface. PMID:26159229

  5. Well-Defined Nanostructured, Single-Crystalline TiO2 Electron Transport Layer for Efficient Planar Perovskite Solar Cells.

    PubMed

    Choi, Jongmin; Song, Seulki; Hörantner, Maximilian T; Snaith, Henry J; Park, Taiho

    2016-06-28

    An electron transporting layer (ETL) plays an important role in extracting electrons from a perovskite layer and blocking recombination between electrons in the fluorine-doped tin oxide (FTO) and holes in the perovskite layers, especially in planar perovskite solar cells. Dense TiO2 ETLs prepared by a solution-processed spin-coating method (S-TiO2) are mainly used in devices due to their ease of fabrication. Herein, we found that fatal morphological defects at the S-TiO2 interface due to a rough FTO surface, including an irregular film thickness, discontinuous areas, and poor physical contact between the S-TiO2 and the FTO layers, were inevitable and lowered the charge transport properties through the planar perovskite solar cells. The effects of the morphological defects were mitigated in this work using a TiO2 ETL produced from sputtering and anodization. This method produced a well-defined nanostructured TiO2 ETL with an excellent transmittance, single-crystalline properties, a uniform film thickness, a large effective area, and defect-free physical contact with a rough substrate that provided outstanding electron extraction and hole blocking in a planar perovskite solar cell. In planar perovskite devices, anodized TiO2 ETL (A-TiO2) increased the power conversion efficiency by 22% (from 12.5 to 15.2%), and the stabilized maximum power output efficiency increased by 44% (from 8.9 to 12.8%) compared with S-TiO2. This work highlights the importance of the ETL geometry for maximizing device performance and provides insights into achieving ideal ETL morphologies that remedy the drawbacks observed in conventional spin-coated ETLs.

  6. Photovoltaic Characterization and Electrochemical Impedance Spectroscopy Analysis of Dye-Sensitized Solar Cells Based on Composite TiO2-MWCNT Photoelectrodes

    NASA Astrophysics Data System (ADS)

    Parvazian, E.; Karimzadeh, F.; Enayati, M. H.

    2014-05-01

    Dye-sensitized solar cells (DSSCs) use the effect of light on dye molecules to generate electricity through a photoelectrochemical mechanism. The aim of this study is to synthesize nanostructured DSSCs based on titania-multiwalled carbon nanotube (TiO2-MWCNT) composite photoelectrodes and improve their performance and efficiency. DSSCs were fabricated based on single-layer TiO2-MWCNT photoelectrodes with various weight percentages of multiwalled carbon nanotubes and bilayer TiO2/TiO2-2%MWCNT photoelectrodes. The microstructure and thickness of the anodic layers were characterized by field-emission scanning electron microscopy and optical microscopy. Also, to compare the conversion efficiency and determine the electron behavior in the electrical equivalent circuit of these cells, photovoltaic characterization and electrochemical impedance spectroscopy (EIS) analysis were used. The DSSC based on a single-layer TiO2-2%MWCNT electrode, compared with other single-layer DSSCs in this study, had the highest conversion efficiency of 3.9% (for anodic layer thickness of 9 μm). The efficiency of the solar cell with the bilayer TiO2/TiO2-2%MWCNT photoelectrode, in comparison with the single-layer solar cell with the TiO2-2%MWCNT electrode, showed a 23% increase from 4.33% to 5.35% (for anodic layer thickness of 18 μm). EIS analysis indicated that the charge-transport resistance of the DSSC based on the bilayer photoelectrode, in comparison with the single-layer TiO2 and TiO2-2%MWCNT solar cells, was decreased by 68% and 57%, respectively.

  7. Enhanced performance of TiO2 nanoparticle and aerogel composite electrode for dye sensitized solar cell.

    PubMed

    Kim, Chang-Yeoul; Park, Yu-Sik; Hwang, Hae-Jin

    2012-04-01

    To evaluate the effects of specific surface area to the photocurrent conversion efficiency of dye-sensitized solar cell (DSC), we adopted TiO2 aerogel (TA)/nanoparticle (TP) composite as a photoelectrode. We prepared three types of photoelectrodes, TPs, TAs, and TATPs (1:1 TAs and TPs composite photoelectrode). The performance of TATP composite electrode was compared with that of TP and TAs. TATPs showed the improved cell efficiency, more than 0.5%, compared with a reference TPs below 15 micrometer thickness. Although the introduction of TAs increases the specific surface area for the dye adsorption, DSC composed of only TAs does not show the best efficiency result due to the crack generation. In conclusion, to produce the best photocurrent conversion efficiency, the high specific surface area of TiO2 photoelectrode for high dye adsorption should be balanced with proper control of the good electron transfer path. PMID:22849065

  8. Recombination reduction on lead halide perovskite solar cells based on low temperature synthesized hierarchical TiO2 nanorods

    NASA Astrophysics Data System (ADS)

    Jaramillo-Quintero, Oscar A.; Solís de La Fuente, Mauricio; Sanchez, Rafael S.; Recalde, Ileana B.; Juarez-Perez, Emilio J.; Rincón, Marina E.; Mora-Seró, Iván

    2016-03-01

    Intensive research on the electron transport material (ETM) has been pursued to improve the efficiency of perovskite solar cells (PSCs) and decrease their cost. More importantly, the role of the ETM layer is not yet fully understood, and research on new device architectures is still needed. Here, we report the use of three-dimensional (3D) TiO2 with a hierarchical architecture based on rutile nanorods (NR) as photoanode material for PSCs. The proposed hierarchical nanorod (HNR) films were synthesized by a two-step low temperature (180 °C) hydrothermal method, and consist of TiO2 nanorod trunks with optimal lengths of 540 nm and TiO2 nanobranches with lengths of 45 nm. Different device configurations were fabricated with TiO2 structures (compact layer, NR and HNR) and CH3NH3PbI3, using different synthetic routes, as the active material. PSCs based on HNR-CH3NH3PbI3 achieved the highest power conversion efficiency compared to PSCs with other TiO2 structures. This result can be ascribed mainly to lower charge recombination as determined by impedance spectroscopy. Furthermore, we have observed that the CH3NH3PbI3 perovskite deposited by the two-step route shows higher efficiency, surface coverage and infiltration within the structure of 3D HNR than the one-step CH3NH3PbI3-xClx perovskite.Intensive research on the electron transport material (ETM) has been pursued to improve the efficiency of perovskite solar cells (PSCs) and decrease their cost. More importantly, the role of the ETM layer is not yet fully understood, and research on new device architectures is still needed. Here, we report the use of three-dimensional (3D) TiO2 with a hierarchical architecture based on rutile nanorods (NR) as photoanode material for PSCs. The proposed hierarchical nanorod (HNR) films were synthesized by a two-step low temperature (180 °C) hydrothermal method, and consist of TiO2 nanorod trunks with optimal lengths of 540 nm and TiO2 nanobranches with lengths of 45 nm. Different

  9. Mesoporous TiO2 Bragg Stack Templated by Graft Copolymer for Dye-sensitized Solar Cells

    PubMed Central

    Park, Jung Tae; Chi, Won Seok; Kim, Sang Jin; Lee, Daeyeon; Kim, Jong Hak

    2014-01-01

    Organized mesoporous TiO2 Bragg stacks (om-TiO2 BS) consisting of alternating high and low refractive index organized mesoporous TiO2 (om-TiO2) films were prepared to enhance dye loading, light harvesting, electron transport, and electrolyte pore-infiltration in dye-sensitized solar cells (DSSCs). The om-TiO2 films were synthesized via a sol-gel reaction using amphiphilic graft copolymers consisting of poly(vinyl chloride) backbones and poly(oxyethylene methacrylate) side chains, i.e., PVC-g-POEM as templates. To generate high and low index films, the refractive index of om-TiO2 film was tuned by controlling the grafting ratio of PVC-g-POEM via atomic transfer radical polymerization (ATRP). A polymerized ionic liquid (PIL)-based DSSC fabricated with a 1.2-μm-thick om-TiO2 BS-based photoanode exhibited an efficiency of 4.3%, which is much higher than that of conventional DSSCs with a nanocrystalline TiO2 layer (nc-TiO2 layer) (1.7%). A PIL-based DSSC with a heterostructured photoanode consisting of 400-nm-thick organized mesoporous TiO2 interfacial (om-TiO2 IF) layer, 7-μm-thick nc-TiO2, and 1.2-μm-thick om-TiO2 BS as the bottom, middle and top layers, respectively, exhibited an excellent efficiency of 7.5%, which is much higher than that of nanocrystaline TiO2 photoanode (3.5%). PMID:24980936

  10. Carbonate Doping in TiO2 Microsphere: The Key Parameter Influencing Others for Efficient Dye Sensitized Solar Cell

    PubMed Central

    Seddigi, Zaki S.; Ahmed, Saleh A.; Sardar, Samim; Pal, Samir Kumar

    2016-01-01

    Four key parameters namely light trapping, density of light harvesting centre, photoinduced electron injection and electron transport without self-recombination are universally important across all kinds of solar cells. In the present study, we have considered the parameters in the context of a model Dye Sensitized Solar Cell (DSSC). Our experimental studies reveal that carbonate doping of TiO2 mesoporous microspheres (doped MS) makes positive influence to all the above mentioned key parameters responsible for the enhanced solar cell efficiency. A simple method has been employed to synthesize the doped MS for the photoanode of a N719 (ruthenium dye)-based DSSC. A detail electron microscopy has been used to characterize the change in morphology of the MS upon doping. The optical absorption spectrum of the doped MS reveals significant shift of TiO2 (compared to that of the MS without doping) towards maximum solar radiance (~500 nm) and the excellent scattering in the entire absorption band of the sensitizing dye (N719). Finally, and most importantly, for the first time we have demonstrated that the solar cells with doped MS offers better efficiency (7.6%) in light harvesting compared to MS without doping (5.2%) and also reveal minimum self recombination of photoelectrons in the redox chain. PMID:26984765

  11. Improved performance of dye-sensitized solar cell based on TiO2 photoanode with FTO glass and film both treated by TiCl4

    NASA Astrophysics Data System (ADS)

    Li, Jinlun; Zhang, Haiyan; Wang, Wenguang; Qian, Yannan; Li, Zhenghui

    2016-11-01

    The dye-sensitized solar cell (DSSC) based on TiO2 photoanode with FTO glass and TiO2 film co-treated by TiCl4 were fabricated. The effects of TiCl4 treatment on the photovoltaic performance of the DSSCs were investigated. TiCl4 treatment of the FTO glass resulted in the formation of a compact TiO2 thin layer on its surface, which could increase the electron collection efficiency. Meanwhile, TiCl4 treatment of the TiO2 film could fill gaps between nanoparticles in the TiO2 film, leading to better electron transfer. These advantages make the DSSC exhibit a highest conversion efficiency of 3.34% under a simulated solar irradiation with an intensity of 100 mW/cm2 (1 sun), increased by 38% compared with that of the untreated DSSC.

  12. High-temperature annealing of TiO2 nanotube membranes for efficient dye-sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Mohammadpour, Fatemeh; Altomare, Marco; So, Seulgi; Lee, Kiyoung; Mokhtar, Mohamed; Alshehri, Abdelmohsen; Al-Thabaiti, Shaeel A.; Schmuki, Patrik

    2016-01-01

    We fabricate photo-anodes by transferring anodic TiO2 nanotube membranes in tube-top-down configuration on FTO glass, and use them for constructing frontside illuminated dye-sensitized solar cells. Prior to solar cell construction, the tube-based photo-anodes are crystallized at different temperatures (400-800 °C), and the effects of tube electron transport properties on the photovoltaic performance of the solar cells are investigated. We show that improved solar cell efficiencies (up to ca. 8.0%) can be reached by high-temperature treatment of the tube membranes. Consistent with electron transport time measurements, remarkably enhanced electron mobility is enabled when tube membranes are crystallized at 600 °C.

  13. 19.2% Efficient InP Heterojunction Solar Cell with Electron-Selective TiO2 Contact

    PubMed Central

    2015-01-01

    We demonstrate an InP heterojunction solar cell employing an ultrathin layer (∼10 nm) of amorphous TiO2 deposited at 120 °C by atomic layer deposition as the transparent electron-selective contact. The TiO2 film selectively extracts minority electrons from the conduction band of p-type InP while blocking the majority holes due to the large valence band offset, enabling a high maximum open-circuit voltage of 785 mV. A hydrogen plasma treatment of the InP surface drastically improves the long-wavelength response of the device, resulting in a high short-circuit current density of 30.5 mA/cm2 and a high power conversion efficiency of 19.2%. PMID:25679010

  14. 19.2% Efficient InP Heterojunction Solar Cell with Electron-Selective TiO2 Contact

    DOE PAGES

    Yin, Xingtian; Battaglia, Corsin; Lin, Yongjing; Chen, Kevin; Hettick, Mark; Zheng, Maxwell; Chen, Cheng-Ying; Kiriya, Daisuke; Javey, Ali

    2014-09-25

    We demonstrate an InP heterojunction solar cell employing an ultrathin layer (~10 nm) of amorphous TiO2 deposited at 120°C by atomic layer deposition as the transparent electron-selective contact. The TiO2 film selectively extracts minority electrons from the conduction band of p-type InP while blocking the majority holes due to the large valence band offset, enabling a high maximum open-circuit voltage of 785 mV. Lastly, a hydrogen plasma treatment of the InP surface drastically improves the long-wavelength response of the device, resulting in a high short-circuit current density of 30.5 mA/cm2 and a high power conversion efficiency of 19.2%.

  15. Photodeposition of Ag2S on TiO2 nanorod arrays for quantum dot-sensitized solar cells

    PubMed Central

    2013-01-01

    Ag2S quantum dots were deposited on the surface of TiO2 nanorod arrays by a two-step photodeposition. The prepared TiO2 nanorod arrays as well as the Ag2S deposited electrodes were characterized by X-ray diffraction, scanning electron microscope, and transmission electron microscope, suggesting a large coverage of Ag2S quantum dots on the ordered TiO2 nanorod arrays. UV–vis absorption spectra of Ag2S deposited electrodes show a broad absorption range of the visible light. The quantum dot-sensitized solar cells (QDSSCs) based on these electrodes were fabricated, and the photoelectrochemical properties were examined. A high photocurrent density of 10.25 mA/cm2 with a conversion efficiency of 0.98% at AM 1.5 solar light of 100 mW/cm2 was obtained with an optimal photodeposition time. The performance of the QDSSC at different incident light intensities was also investigated. The results display a better performance at a lower incident light level with a conversion efficiency of 1.25% at 47 mW/cm2. PMID:23286551

  16. Enhanced conversion efficiency of dye-sensitized solar cells using a CNT-incorporated TiO2 slurry-based photoanode

    NASA Astrophysics Data System (ADS)

    Cai, Jiaoping; Chen, Zexiang; Li, Jun; Wang, Yan; Xiang, Dong; Zhang, Jijun; Li, Hai

    2015-02-01

    A new titanium dioxide (TiO2) slurry formulation is herein reported for the fabrication of TiO2 photoanode for use in dye-sensitized solar cells (DSSCs). The prepared TiO2 photoanode featured a highly uniform mesoporous structure with well-dispersed TiO2 nanoparticles. The energy conversion efficiency of the resulting TiO2 slurry-based DSSC was ˜63% higher than that achieved by a DSSC prepared using a commercial TiO2 slurry. Subsequently, the incorporation of acid-treated multi-walled carbon nanotubes (CNTs) into the TiO2 slurry was examined. More specifically, the effect of varying the concentration of the CNTs in this slurry on the performance of the resulting DSSCs was studied. The chemical state of the CNTs-incorporated TiO2 photoanode was investigated by Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy. A high energy conversion efficiency of 6.23% was obtained at an optimum CNT concentration of ˜0.06 wt.%. The obtained efficiency corresponds to a 63% enhancement when compared with that obtained from a DSSC based on a commercial TiO2 slurry. The higher efficiency was attributed to the improvement in the collection and transport of excited electrons in the presence of the CNTs.

  17. Inverted organic solar cells using a solution-processed TiO2/CdSe electron transport layer to improve performance

    NASA Astrophysics Data System (ADS)

    Ma, Xiaoxiao; Xiong, Zhicheng; Wang, Wen; Zhang, Luming; Wu, Sujuan; Lu, Xubing; Gao, Xingsen; Shui, Lingling; Liu, Jun-Ming

    2016-04-01

    In the present work, cadmium selenide (CdSe) nanoparticles are deposited directly on TiO2 film to fabricate the TiO2/CdSe interlayer by a chemical bath deposition method. The inverted organic solar cells using poly(3-hexylthiophene) (P3HT) and [6,6]-phenyl C61 butyric acid methyl ester (PCBM) bulk heterojunction as an active layer and TiO2/CdSe interlayer as an electron transport layer (ETL) are fabricated in air. A series of microstructural, photo-electronic, and electrochemical characterizations on these cells are performed. The TiO2/CdSe structure with respect to either the TiO2 layer or the CdSe layer as the ETL exhibits significantly enhanced external quantum efficiency (EQE) in the visible region. The photoluminescence (PL) measurement shows that the exciton dissociation in the TiO2/CdSe structure is more effective than that in either the TiO2 or CdSe structure. The Nyquist plots obtained from electrochemical impedance spectroscopy (EIS) implies that the charge recombination in the TiO2/CdSe structure can be suppressed with respect to that in either the CdSe or TiO2 structure. The photovoltaic performances of the cells with the TiO2/CdSe ETL are clearly improved compared with the reference cells only with the TiO2 layer or CdSe layer as the ETL.

  18. Comparison of Dye-Sensitized Rutile- and Anatase-Based TiO2 Solar Cells

    SciTech Connect

    Park, N. G.; van de Lagemaat, J.; Frank, A. J.

    2000-01-01

    The objective of this work is to develop and optimize the new dye-sensitized solar cell technology. In view of the infancy of rutile material development for solar cells, the PV response of the dye-sensitized rutile-based solar cell is remarkably close to that of the anatase-based cell.

  19. Treatment of TiO2 with COOH-functionalized germanium nanoparticles to enhance the photocurrent of dye-sensitized solar cells.

    PubMed

    Kim, Chang-Ho; Ha, Eun-Sung; Baik, Hionsuck; Kim, Kang-Jin

    2011-03-01

    A dye-sensitized solar cell (DSSC) containing a TiO(2) film treated with COOH-functionalized germanium nanoparticles (Ge-COOH Nps) exhibited a higher short-circuit photocurrent density (J(sc); 15.4 mA cm(-2)) compared to the corresponding untreated DSSC (13.4 mA cm(-2)) using N719 and a 12 μm thick TiO(2) film at 100 mW cm(-2). The amount of N719 attached to the treated TiO(2) film was 21% greater than that attached to the untreated TiO(2) film. Enhancement of the J(sc) value by 15% was attributed mostly to an intramolecular charge transfer from N719 attached to the Ge-COOH Nps to the TiO(2) conduction band through the Ge-COOH Nps.

  20. Metal-free organic dyes for TiO2 and ZnO dye-sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Selopal, Gurpreet Singh; Wu, Hui-Ping; Lu, Jianfeng; Chang, Yu-Cheng; Wang, Mingkui; Vomiero, Alberto; Concina, Isabella; Diau, Eric Wei-Guang

    2016-01-01

    We report the synthesis and characterization of new metal-free organic dyes (namely B18, BTD-R, and CPTD-R) which designed with D-π-A concept to extending the light absorption region by strong conjugation group of π-linker part and applied as light harvester in dye sensitized solar cells (DSSCs). We compared the photovoltaic performance of these dyes in two different photoanodes: a standard TiO2 mesoporous photoanode and a ZnO photoanode composed of hierarchically assembled nanostructures. The results demonstrated that B18 dye has better photovoltaic properties compared to other two dyes (BTD-R and CPTD-R) and each dye has higher current density (Jsc) when applied to hierarchical ZnO nanocrystallites than the standard TiO2 mesoporous film. Transient photocurrent and photovoltage decay measurements (TCD/TVD) were applied to systematically study the charge transport and recombination kinetics in these devices, showing the electron life time (τR) of B18 dye in ZnO and TiO2 based DSSCs is higher than CPTD-R and BTD-R based DSSCs, which is consistent with the photovoltaic performances. The conversion efficiency in ZnO based DSSCs can be further boosted by 35%, when a compact ZnO blocking layer (BL) is applied to inhibit electron back reaction.

  1. FeS2 quantum dots sensitized nanostructured TiO2 solar cell: photoelectrochemical and photoinduced absorption spectroscopy studies

    NASA Astrophysics Data System (ADS)

    Bedja, I.

    2011-09-01

    Thin films of nanostructured TiO2 have been modified with FeS2 (pyrite) nano-particles by a low temperature chemical reaction of iron pentacarbonyl with sulfur in xylene. Quantum size effects are manifested by the observation of a blue shift in both absorption and photocurrent action spectra. PIA (Photoinduced absorption spectroscopy), where the excitation is provided by a square-wave modulated (on/off) monochromatic light emitting diode, is a multipurpose tool in the study of dye-sensitized solar cells. Here, PIA is used to study quantum-dot modified TiO2 nanostructured electrodes. The PIA spectra obtained give evidence for long-lived photoinduced charge separation: electrons are injected into the metal oxide and holes are left behind in the FeS2 quantum dot. Time-resolved PIA shows that recombination between electrons and holes occurs on a millisecond timescale. The Incident-Photon-to-Current Efficiency of about 23 % was obtained at 400 nm excitation. The performances of TiO2 electrodes modified with FeS2 are relatively low, which is explained by the presence of FeS2 phases other than the photoactive pyrite phase, as follows from the XRD spectrum.

  2. Metal-free organic dyes for TiO2 and ZnO dye-sensitized solar cells

    PubMed Central

    Selopal, Gurpreet Singh; Wu, Hui-Ping; Lu, Jianfeng; Chang, Yu-Cheng; Wang, Mingkui; Vomiero, Alberto; Concina, Isabella; Diau, Eric Wei-Guang

    2016-01-01

    We report the synthesis and characterization of new metal-free organic dyes (namely B18, BTD-R, and CPTD-R) which designed with D-π-A concept to extending the light absorption region by strong conjugation group of π-linker part and applied as light harvester in dye sensitized solar cells (DSSCs). We compared the photovoltaic performance of these dyes in two different photoanodes: a standard TiO2 mesoporous photoanode and a ZnO photoanode composed of hierarchically assembled nanostructures. The results demonstrated that B18 dye has better photovoltaic properties compared to other two dyes (BTD-R and CPTD-R) and each dye has higher current density (Jsc) when applied to hierarchical ZnO nanocrystallites than the standard TiO2 mesoporous film. Transient photocurrent and photovoltage decay measurements (TCD/TVD) were applied to systematically study the charge transport and recombination kinetics in these devices, showing the electron life time (τR) of B18 dye in ZnO and TiO2 based DSSCs is higher than CPTD-R and BTD-R based DSSCs, which is consistent with the photovoltaic performances. The conversion efficiency in ZnO based DSSCs can be further boosted by 35%, when a compact ZnO blocking layer (BL) is applied to inhibit electron back reaction. PMID:26738698

  3. Mechanism of biphasic charge recombination and accumulation in TiO2 mesoporous structured perovskite solar cells.

    PubMed

    Wang, Hao-Yi; Wang, Yi; Yu, Man; Han, Jun; Guo, Zhi-Xin; Ai, Xi-Cheng; Zhang, Jian-Ping; Qin, Yujun

    2016-04-28

    Organic-inorganic halide perovskite solar cells are becoming the next big thing in the photovoltaic field owing to their rapidly developing photoelectric conversion performance. Herein, mesoporous structured perovskite devices with various perovskite grain sizes are fabricated by a sequential dropping method, and the charge recombination dynamics is investigated by transient optical-electric measurements. All devices exhibit an overall power conversion efficiency around 15%. More importantly, a biphasic trap-limited charge recombination process is proposed and interpreted by taking into account the specific charge accumulation mechanism in perovskite solar cells. At low Fermi levels, photo-generated electrons predominately populate in the perovskite phase, while at high Fermi levels, most electrons occupy traps in mesoporous TiO2. As a result, the dynamics of charge recombination is, respectively, dominated by the perovskite phase and mesoporous TiO2 in these two cases. The present work would give a new perspective on the charge recombination process in meso-structured perovskite solar cells.

  4. Mechanism of biphasic charge recombination and accumulation in TiO2 mesoporous structured perovskite solar cells.

    PubMed

    Wang, Hao-Yi; Wang, Yi; Yu, Man; Han, Jun; Guo, Zhi-Xin; Ai, Xi-Cheng; Zhang, Jian-Ping; Qin, Yujun

    2016-04-28

    Organic-inorganic halide perovskite solar cells are becoming the next big thing in the photovoltaic field owing to their rapidly developing photoelectric conversion performance. Herein, mesoporous structured perovskite devices with various perovskite grain sizes are fabricated by a sequential dropping method, and the charge recombination dynamics is investigated by transient optical-electric measurements. All devices exhibit an overall power conversion efficiency around 15%. More importantly, a biphasic trap-limited charge recombination process is proposed and interpreted by taking into account the specific charge accumulation mechanism in perovskite solar cells. At low Fermi levels, photo-generated electrons predominately populate in the perovskite phase, while at high Fermi levels, most electrons occupy traps in mesoporous TiO2. As a result, the dynamics of charge recombination is, respectively, dominated by the perovskite phase and mesoporous TiO2 in these two cases. The present work would give a new perspective on the charge recombination process in meso-structured perovskite solar cells. PMID:27076212

  5. Perovskite Solar Cells: Moth-Eye TiO2 Layer for Improving Light Harvesting Efficiency in Perovskite Solar Cells (Small 18/2016).

    PubMed

    Kang, Seong Min; Jang, Segeun; Lee, Jong-Kwon; Yoon, Jungjin; Yoo, Dong-Eun; Lee, Jin-Wook; Choi, Mansoo; Park, Nam-Gyu

    2016-05-01

    A moth-eye patterned mesoporous (mp) TiO2 layer is fabricated in the form of submicron scale by using lithography, nano-imprinting and polydimethyl siloxane (PDMS) stamping methods. On page 2443, M. Choi, N.-G. Park, and co-workers demonstrate an excellent light harvesting property of perovskite solar cell by employing the moth-eye nanostructured mp-TiO2 film. These novel fabrication methods are expected to be optically beneficial to opto-electronic devices.

  6. Amphiphilic block-graft copolymer templates for organized mesoporous TiO2 films in dye-sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Lim, Jung Yup; Lee, Chang Soo; Lee, Jung Min; Ahn, Joonmo; Cho, Hyung Hee; Kim, Jong Hak

    2016-01-01

    Amphiphilic block-graft copolymers composed of poly(styrene-b-butadiene-b-styrene) (SBS) backbone and poly(oxyethylene methacrylate) (POEM) side chains are synthesized and combined with hydrophilically preformed TiO2 (Pre-TiO2), which works as a structural binder as well as titania source. This results in the formation of crack free, 6-μm-thick, organized mesoporous TiO2 (OM-TiO2) films via one-step doctor-blading based on self-assembly of SBS-g-POEM as well as preferential interaction of POEM chains with Pre-TiO2. SBS-g-POEM with different numbers of ethylene oxide repeating units, SBS-g-POEM(500) and SBS-g-POEM(950), are used to form OM-TiO2(500) and OM-TiO2(950), respectively. The efficiencies of dye-sensitized solar cells (DSSCs) with a quasi-solid-state polymer electrolyte reach 5.7% and 5.8% at 100 mW/cm2 for OM-TiO2(500) and OM-TiO2(950), respectively. The surface area of OM-TiO2(950) was greater than that of OM-TiO2(500) but the light reflectance was lower in the former, which is responsible for similar efficiency. Both DSSCs exhibit much higher efficiency than one (4.8%) with randomly-organized particulate TiO2 (Ran-TiO2), which is attributed to the higher dye loading, reduced charge recombination and improved pore infiltration of OM-TiO2. When utilizing poly((1-(4-ethenylphenyl)methyl)-3-butyl-imidazolium iodide) (PEBII) and mesoporous TiO2 spheres as the solid electrolyte and the scattering layer, the efficiency increases up to 7.5%, one of the highest values for N719-based solid-state DSSCs.

  7. Mesoporous TiO2 Yolk-Shell Microspheres for Dye-sensitized Solar Cells with a High Efficiency Exceeding 11%.

    PubMed

    Li, Zhao-Qian; Chen, Wang-Chao; Guo, Fu-Ling; Mo, Li-E; Hu, Lin-Hua; Dai, Song-Yuan

    2015-09-18

    Yolk-shell TiO2 microspheres were synthesized via a one-pot template-free solvothermal method building on the aldol condensation reaction of acetylacetone. This unique structure shows superior light scattering ability resulting in power conversion efficiency as high as 11%. This work provided a new synthesis system for TiO2 microspheres from solid to hollow and a novel material platform for high performance solar cells.

  8. Mesoporous TiO2 Yolk-Shell Microspheres for Dye-sensitized Solar Cells with a High Efficiency Exceeding 11%

    PubMed Central

    Li, Zhao-Qian; Chen, Wang-Chao; Guo, Fu-Ling; Mo, Li-E; Hu, Lin-Hua; Dai, Song-Yuan

    2015-01-01

    Yolk-shell TiO2 microspheres were synthesized via a one-pot template-free solvothermal method building on the aldol condensation reaction of acetylacetone. This unique structure shows superior light scattering ability resulting in power conversion efficiency as high as 11%. This work provided a new synthesis system for TiO2 microspheres from solid to hollow and a novel material platform for high performance solar cells. PMID:26384004

  9. Optimisation of ruthenium dye sensitised solar cells efficiency via Sn diffusion into the TiO2 mesoporous layer.

    PubMed

    Andrei, Codrin; Zerulla, Dominic

    2013-01-01

    Dye sensitised solar cells (DSCs) typically include a mesoporous titanium dioxide (TiO2) scaffold, sensitised with an adsorbed dye, as the main active element responsible for the photon absorption and charge separation functionalities. The sintering process employed in the TiO2 active layer fabrication plays a crucial role in the formation of the nanoparticle (NP) scaffold and hence in the performance of a dye sensitised solar cell, as it allows the particles to form efficient inter-crystalline electric contacts providing high electron conductivity. Furthermore, the DSC design requires a conductive transparent top electrode which is typically made of fluorinated stannic oxide. Here we report on a highly spatially resolved scanning electron microscopy study in conjunction with focussed ion beam milling and energy dispersive X-ray (EDX) mapping of the distribution of all relevant elements within a DSC subsequent to a classical sintering process in the range of 350°C-550°C. Additionally, the article provides quantitative results regarding the found Sn diffusion and its effect on efficiency confirmed via J-V measurements. The effective spatial resolution of the EDX studies was calculated by Monte Carlo simulations of the electron trajectories and X-ray emission region. This permits to construct a model for the migration of Sn from the transparent conductive oxide into the TiO2 scaffold, resulting in alterations in the composition of the complex system which has a direct effect on the DSC performance. J-V measurements conclude that sintering temperature of 500°C is close to the optimum regarding Sn diffusion enhancement of DSCs. Sintering temperatures above 500°C were causing a drop in the DSC efficiency and are therefore not recommended. In order to optimize the DSC efficiency, the results are summarized by a model that explains how the efficiency varies with the Sn diffusion process.

  10. Optimisation of Ruthenium Dye Sensitised Solar Cells Efficiency via Sn Diffusion into the TiO2 Mesoporous Layer

    PubMed Central

    Andrei, Codrin; Zerulla, Dominic

    2013-01-01

    Dye sensitised solar cells (DSCs) typically include a mesoporous titanium dioxide (TiO2) scaffold, sensitised with an adsorbed dye, as the main active element responsible for the photon absorption and charge separation functionalities. The sintering process employed in the TiO2 active layer fabrication plays a crucial role in the formation of the nanoparticle (NP) scaffold and hence in the performance of a dye sensitised solar cell, as it allows the particles to form efficient inter-crystalline electric contacts providing high electron conductivity. Furthermore, the DSC design requires a conductive transparent top electrode which is typically made of fluorinated stannic oxide. Here we report on a highly spatially resolved scanning electron microscopy study in conjunction with focussed ion beam milling and energy dispersive X-ray (EDX) mapping of the distribution of all relevant elements within a DSC subsequent to a classical sintering process in the range of 350°C–550°C. Additionally, the article provides quantitative results regarding the found Sn diffusion and its effect on efficiency confirmed via J-V measurements. The effective spatial resolution of the EDX studies was calculated by Monte Carlo simulations of the electron trajectories and X-ray emission region. This permits to construct a model for the migration of Sn from the transparent conductive oxide into the TiO2 scaffold, resulting in alterations in the composition of the complex system which has a direct effect on the DSC performance. J-V measurements conclude that sintering temperature of 500°C is close to the optimum regarding Sn diffusion enhancement of DSCs. Sintering temperatures above 500°C were causing a drop in the DSC efficiency and are therefore not recommended. In order to optimize the DSC efficiency, the results are summarized by a model that explains how the efficiency varies with the Sn diffusion process. PMID:23704956

  11. Efficiency Enhancement of Nanotextured Black Silicon Solar Cells Using Al2O3/TiO2 Dual-Layer Passivation Stack Prepared by Atomic Layer Deposition.

    PubMed

    Wang, Wei-Cheng; Tsai, Meng-Chen; Yang, Jason; Hsu, Chuck; Chen, Miin-Jang

    2015-05-20

    In this study, efficient nanotextured black silicon (NBSi) solar cells composed of silicon nanowire arrays and an Al2O3/TiO2 dual-layer passivation stack on the n(+) emitter were fabricated. The highly conformal Al2O3 and TiO2 surface passivation layers were deposited on the high-aspect-ratio surface of the NBSi wafers using atomic layer deposition. Instead of the single Al2O3 passivation layer with a negative oxide charge density, the Al2O3/TiO2 dual-layer passivation stack treated with forming gas annealing provides a high positive oxide charge density and a low interfacial state density, which are essential for the effective field-effect and chemical passivation of the n(+) emitter. In addition, the Al2O3/TiO2 dual-layer passivation stack suppresses the total reflectance over a broad range of wavelengths (400-1000 nm). Therefore, with the Al2O3/TiO2 dual-layer passivation stack, the short-circuit current density and efficiency of the NBSi solar cell were increased by 11% and 20%, respectively. In conclusion, a high efficiency of 18.5% was achieved with the NBSi solar cells by using the n(+)-emitter/p-base structure passivated with the Al2O3/TiO2 stack.

  12. Efficiency Enhancement of Nanotextured Black Silicon Solar Cells Using Al2O3/TiO2 Dual-Layer Passivation Stack Prepared by Atomic Layer Deposition.

    PubMed

    Wang, Wei-Cheng; Tsai, Meng-Chen; Yang, Jason; Hsu, Chuck; Chen, Miin-Jang

    2015-05-20

    In this study, efficient nanotextured black silicon (NBSi) solar cells composed of silicon nanowire arrays and an Al2O3/TiO2 dual-layer passivation stack on the n(+) emitter were fabricated. The highly conformal Al2O3 and TiO2 surface passivation layers were deposited on the high-aspect-ratio surface of the NBSi wafers using atomic layer deposition. Instead of the single Al2O3 passivation layer with a negative oxide charge density, the Al2O3/TiO2 dual-layer passivation stack treated with forming gas annealing provides a high positive oxide charge density and a low interfacial state density, which are essential for the effective field-effect and chemical passivation of the n(+) emitter. In addition, the Al2O3/TiO2 dual-layer passivation stack suppresses the total reflectance over a broad range of wavelengths (400-1000 nm). Therefore, with the Al2O3/TiO2 dual-layer passivation stack, the short-circuit current density and efficiency of the NBSi solar cell were increased by 11% and 20%, respectively. In conclusion, a high efficiency of 18.5% was achieved with the NBSi solar cells by using the n(+)-emitter/p-base structure passivated with the Al2O3/TiO2 stack. PMID:25919200

  13. Efficient Planar Perovskite Solar Cells with Reduced Hysteresis and Enhanced Open Circuit Voltage by Using PW12-TiO2 as Electron Transport Layer.

    PubMed

    Huang, Chun; Liu, Canjun; Di, Yunxiang; Li, Wenzhang; Liu, Fangyang; Jiang, Liangxing; Li, Jie; Hao, Xiaojing; Huang, Haitao

    2016-04-01

    An electron transport layer is essential for effective operation of planar perovskite solar cells. In this Article, PW12-TiO2 composite was used as the electron transport layer for the planar perovskite solar cell in the device structure of fluorine-doped tin oxide (FTO)-glass/PW12-TiO2/perovskite/spiro-OMeTAD/Au. A proper downward shift of the conduction band minimum (CBM) enhanced electron extraction from the perovskite layer to the PW12-TiO2 composite layer. Consequently, the common hysteresis effect in TiO2-based planar perovskite solar cells was significantly reduced and the open circuit voltage was greatly increased to about 1.1 V. Perovskite solar cells using the PW12-TiO2 compact layer showed an efficiency of 15.45%. This work can contribute to the studies on the electron transport layer and interface engineering for the further development of perovskite solar cells.

  14. Porous (001)-faceted anatase TiO2 nanorice thin film for efficient dye-sensitized solar cell

    NASA Astrophysics Data System (ADS)

    Shah, Athar Ali; Umar, Akrajas Ali; Mat Salleh, Muhamad

    2016-01-01

    Anatase TiO2 structures with nanorice-like morphology and high exposure of (001) facet has been successfully synthesized on an ITO surface using ammonium Hexafluoro Titanate and Hexamethylenetetramine as precursor and capping agent, respectively, under a microwave-assisted liquid-phase deposition method. These anatase TiO2 nanoparticles were prepared within five minutes of reaction time by utilizing an inverter microwave system at a normal atmospheric pressure. The morphology and the size (approximately from 6 to 70 nm) of these nanostructures can be controlled. Homogenous, porous, 5.64 ± 0.002 μm thick layer of spongy-nanorice with facets (101) and (001) was grown on ITO substrate and used as a photo-anode in a dye-sensitized solar cell (DSSC). This solar cell device has emerged out with 4.05 ± 0.10% power conversion efficiency (PCE) and 72% of incident photon-to-current efficiency (IPCE) under AM1.5 G illumination.

  15. Improved performance of Ag-doped TiO2 synthesized by modified sol-gel method as photoanode of dye-sensitized solar cell

    NASA Astrophysics Data System (ADS)

    Gupta, Arun Kumar; Srivastava, Pankaj; Bahadur, Lal

    2016-08-01

    Ag-doped TiO2 with Ag content ranging from 1 to 7 mol% was synthesized by a modified sol-gel route, and its performance as the photoanode of dye-sensitized solar cells (DSSCs) was compared with undoped TiO2 photoanode. Titanium(IV)isopropoxide was used as precursor and hexamethylenetetramine as the capping agent. XRD results show the formation of TiO2 nanoparticles with an average crystallite size of 5 nm (1 % Ag-doped TiO2) and 9 nm (undoped TiO2), respectively. The TiO2 nanopowder was used to prepare its thin film photoelectrode using doctor's blade method. Significant improvement in light-to-energy conversion efficiency was achieved when thin films of 1 % Ag-doped TiO2 were applied as photoanode in DSSC taking N719 as the sensitizer dye. As evidenced by EIS measurements, the electron lifetime of DSSC with Ag-doped TiO2 increased from 1.33 (for undoped TiO2) to 2.05 ms. The short-circuit current density ( J sc), open-circuit voltage ( V oc), fill factor (FF) and the overall energy conversion efficiency ( η) were 1.07 mA cm-2, 0.72 V, 0.73 and 0.40 %, respectively, with the use of 1 % Ag-doped TiO2 photoanode, whereas with undoped TiO2 under similar conditions, J sc = 0.63 mA cm-2, V oc = 0.70 V, fill factor 0.45 and conversion efficiency 0.14 % could be obtained. Therefore, compared with the reference DSSC containing an undoped TiO2 photoanode, the power conversion efficiency of the cell based on Ag-doped TiO2 has been remarkably enhanced by ~70 %. The substantial improvement in the device performance is attributed to the reduced band-gap energy, retarded charge recombination and greater surface coverage of the sensitizing dye over Ag-doped TiO2, which ultimately resulted in improved IPCE, J SC and η values.

  16. Combinatorial solar cell libraries for the investigation of different metal back contacts for TiO2-Cu2O hetero-junction solar cells.

    PubMed

    Rühle, S; Barad, H N; Bouhadana, Y; Keller, D A; Ginsburg, A; Shimanovich, K; Majhi, K; Lovrincic, R; Anderson, A Y; Zaban, A

    2014-04-21

    Here we present a comprehensive investigation of TiO2-Cu2O hetero-junction solar cells with different back contacts (Au, ITO, Cu or Ag). Combinatorial hetero-junction libraries consisting of a linear TiO2 thickness gradient produced by spray pyrolysis and a bell shaped Cu2O profile synthesized by pulsed laser deposition were chosen to investigate the impact of the two metal oxide layer thicknesses. The back contacts were deposited as round patches onto a grid of 13 × 13 points, 169 contacts for each contact material, forming a library containing 4 × 13 × 13 = 676 back contacts. Each back contact represented a solar cell with an individual TiO2 and Cu2O thickness. I-V measurements show that all four materials provide an ohmic contact and that the open circuit voltage of ∼300 mV is rather independent of both layer thicknesses and contact material. The size of the Cu2O crystals drastically decreases with distance from the center of deposition, which leads to a drastic increase of series resistance when the crystal size is <50 nm. PMID:24615619

  17. Combinatorial solar cell libraries for the investigation of different metal back contacts for TiO2-Cu2O hetero-junction solar cells.

    PubMed

    Rühle, S; Barad, H N; Bouhadana, Y; Keller, D A; Ginsburg, A; Shimanovich, K; Majhi, K; Lovrincic, R; Anderson, A Y; Zaban, A

    2014-04-21

    Here we present a comprehensive investigation of TiO2-Cu2O hetero-junction solar cells with different back contacts (Au, ITO, Cu or Ag). Combinatorial hetero-junction libraries consisting of a linear TiO2 thickness gradient produced by spray pyrolysis and a bell shaped Cu2O profile synthesized by pulsed laser deposition were chosen to investigate the impact of the two metal oxide layer thicknesses. The back contacts were deposited as round patches onto a grid of 13 × 13 points, 169 contacts for each contact material, forming a library containing 4 × 13 × 13 = 676 back contacts. Each back contact represented a solar cell with an individual TiO2 and Cu2O thickness. I-V measurements show that all four materials provide an ohmic contact and that the open circuit voltage of ∼300 mV is rather independent of both layer thicknesses and contact material. The size of the Cu2O crystals drastically decreases with distance from the center of deposition, which leads to a drastic increase of series resistance when the crystal size is <50 nm.

  18. Synergistic effect between anatase and rutile TiO2 nanoparticles in dye-sensitized solar cells.

    PubMed

    Li, Gonghu; Richter, Christiaan P; Milot, Rebecca L; Cai, Lawrence; Schmuttenmaer, Charles A; Crabtree, Robert H; Brudvig, Gary W; Batista, Victor S

    2009-12-01

    A synergistic effect between anatase and rutile TiO2 is known, in which the addition of rutile can remarkably enhance the photocatalytic activity of anatase in the degradation of organic contaminants. In this study, mixed-phase TiO2 nanocomposites consisting of anatase and rutile nanoparticles (NPs) were prepared for use as photoanodes in dye-sensitized solar cells (DSSCs) and were characterized by using UV-vis spectroscopy, powder X-ray diffraction and scanning electron microscopy. The addition of 10-15% rutile significantly improved light harvesting and the overall solar conversion efficiency of anatase NPs in DSSCs. The underlying mechanism for the synergistic effect in DSSCs is now explored by using time-resolved terahertz spectroscopy. It is clearly demonstrated that photo-excited electrons injected into the rutile NPs can migrate to the conduction band of anatase NPs, enhancing the photocurrent and efficiency. Interfacial electron transfer from rutile to anatase, similar to that in heterogeneous photocatalysis, is proposed to account for the synergistic effect in DSSCs. Our results further suggest that the synergistic effect can be used to explain the beneficial effect of TiCl4 treatment on DSSC efficiency.

  19. The Effect of Scattering Layer on the Performance of Dye-Sensitized Solar Cells Using TiO2 Hollow Spheres/TiO2 Nanoparticles Films as Photoanodes.

    PubMed

    Park, Su Kyung; Suh, Soong-Hyuck; Lee, Min Woo; Yun, Tae Kwan; Bae, Jae Young

    2015-10-01

    TiO2 hollow spheres were successfully synthesized using poly styrene as the template. Dye-sensitized solar cells are fabricated based on double-layered composite films of TiO2 nanoparticles and TiO2 hollow spheres. The photoelectric conversion performances of Dye-sensitized solar cells based on TiO2 nanoparticles/TiO2 nanoparticles, TiO2 nanoparticles/TiO2 hollow spheres and TiO2 hollow spheres/TiO2 hollow spheres double-layered films are investigated, and their photoelectric conversion efficiencies were determined to 4.52, 7.10 and 5.48%, respectively. Dye-sensitized solar cells based on double layered composite films of TiO2 nanoparticles and TiO2 hollow spheres exhibit the highest photo-electric conversion efficiency mainly due to the combined effect of two factors, the high light scattering of over-layer hollow spheres that enhance harvesting light of the Dye-sensitized solar cells and the under-layer TiO2 nanoparticle layer that ensures good electronic contact between TiO2 film and FTO conducting glass. The double layered composite TiO2 film electrodes are a promising development in enhancing the performance of dye-sensitized solar cells.

  20. The Effect of Scattering Layer on the Performance of Dye-Sensitized Solar Cells Using TiO2 Hollow Spheres/TiO2 Nanoparticles Films as Photoanodes.

    PubMed

    Park, Su Kyung; Suh, Soong-Hyuck; Lee, Min Woo; Yun, Tae Kwan; Bae, Jae Young

    2015-10-01

    TiO2 hollow spheres were successfully synthesized using poly styrene as the template. Dye-sensitized solar cells are fabricated based on double-layered composite films of TiO2 nanoparticles and TiO2 hollow spheres. The photoelectric conversion performances of Dye-sensitized solar cells based on TiO2 nanoparticles/TiO2 nanoparticles, TiO2 nanoparticles/TiO2 hollow spheres and TiO2 hollow spheres/TiO2 hollow spheres double-layered films are investigated, and their photoelectric conversion efficiencies were determined to 4.52, 7.10 and 5.48%, respectively. Dye-sensitized solar cells based on double layered composite films of TiO2 nanoparticles and TiO2 hollow spheres exhibit the highest photo-electric conversion efficiency mainly due to the combined effect of two factors, the high light scattering of over-layer hollow spheres that enhance harvesting light of the Dye-sensitized solar cells and the under-layer TiO2 nanoparticle layer that ensures good electronic contact between TiO2 film and FTO conducting glass. The double layered composite TiO2 film electrodes are a promising development in enhancing the performance of dye-sensitized solar cells. PMID:26726506

  1. Efficient dye-sensitised solar cell based on uniform In-doped TiO2 spherical particles

    NASA Astrophysics Data System (ADS)

    Bakhshayesh, A. M.; Farajisafiloo, N.

    2015-07-01

    A facile deposition of uniform photoanode electrodes by a novel anatase-stabilised gel for dye-sensitised solar cells (DSCs) applications is reported. Highly crystalline anatase-TiO2 phase is stabilised by indium nitrate at 500 °C. The electrodes are composed of uniform spherical particles with diameter around 3 µm, containing small nanoparticles with the average grain size of 40 nm, deposited by dip-coating method. X-ray photoelectron spectroscopy reveals that 6 at.% In3+ was incorporated into titania crystal lattice and stabilised anatase phase by limiting the transformation from anatase to rutile phase. UV-Visible spectra show that the stabilised film has lower band gap energy than that of undoped TiO2, extending the absorption of TiO2 into visible region. Electrochemical impedance spectroscopy demonstrates that the anatase-stabilised DSC enjoys less recombination and internal resistances, improving the photovoltaic performance of the cell. The anatase-stabilised DSC has higher power conversion efficiency of 7.48 % than that of unstabilised cell (6.37 %).

  2. Preparation of Nanoporous TiO2 for Dye-Sensitized Solar Cell (DSSC) Using Various Dyes

    NASA Astrophysics Data System (ADS)

    Yuliarto, Brian; Fanani, Fahiem; Fuadi, M. Kasyful; Nugraha

    2010-10-01

    This article reports the development of organic dyes as an attempt to reduce material costs of Dye-Sensitized Solar Cell (DSSC). Indonesia, a country with variety and considerable number of botanical resources, is suitable to perform the research. Indonesian black rice, curcuma, papaya leaf, and the combination were chosen as organic dyes source. Dyes were extracted using organic solvent and adsorbed on mesoporous Titanium Dioxide (TiO2) which has been optimized in our laboratory. The best dyes light absorbance and performance obtained from papaya leaf as chlorophyll dyes that gives two peaks at 432 nm and 664 nm from UV-Vis Spectrophotometry and performance under 100 mW/cm2 Xenon light solar simulator gives VOC = 0.566 Volt, JSC = 0.24 mA/cm2, Fill Factor = 0.33, and efficiency of energy conversion 0,045%.

  3. Tailoring of nanoporous TiO2 spheres with 100-200 nm sizes for efficient dye-sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Yu, Sora; You, Ji Su; Yang, In Seok; Kang, Paul; Rawal, Sher Bahadur; Sung, Sang Do; Lee, Wan In

    2016-09-01

    Highly porous and monodispersed TiO2 spheres (SPs) with diameters in the range of 100-200 nm, notably smaller than the conventional SPs reported thus far, were selectively controlled, and found to be an outstanding building block for the mesoporous TiO2 layer in dye-sensitized solar cells (DSCs). The prepared TiO2 films employing these SPs are highly transparent, and the fabricated DSCs exhibit significantly enhanced photovoltaic performances. Particularly, the 100 nm-sized TiO2 SP (SP100) provides a photovoltaic conversion efficiency (PCE) of 10.66% with a JSC of 17.98 mA/cm2, VOC of 808 mV, and FF of 0.734, which is higher than the PCE of DSCs with the typical 20 nm-sized TiO2 nanoparticle (NP20) or conventional 250 nm-sized SP (SP250). Transient photoelectron spectroscopic analyses revealed that both the electron diffusion coefficient and electron lifetime of the TiO2 layer increase as the size of the SPs decreases. The tiny TiO2 SPs prepared in this work offer distinct advantages in electron transport as well as dye-soaking and electrolyte diffusion.

  4. Hydrothermal growth of TiO2 nanorod arrays and in situ conversion to nanotube arrays for highly efficient quantum dot-sensitized solar cells.

    PubMed

    Huang, Hui; Pan, Lei; Lim, Chiew Keat; Gong, Hua; Guo, Jun; Tse, Man Siu; Tan, Ooi Kiang

    2013-09-23

    TiO2 nanorod (NR) and nanotube (NT) arrays grown on transparent conductive substrates are attractive electrode for solar cells. In this paper, TiO2 NR arrays are hydrothermally grown on FTO substrate, and are in situ converted into NT arrays by hydrothermally etching. The TiO2 NR arrays are reported as single crystalline, but the TiO2 NR arrays are demonstrated to be polycrystalline with a bundle of 2-5 nm single crystalline nanocolumns grown along [001] throughout the whole NR from bottom to top. TiO2 NRs can be converted to NTs by hydrothermal selective etching of the (001) core and remaining the inert sidewall of (110) face. A growth mechanism of the NR and NT arrays is proposed. Quantum dot-sensitized solar cells (QDSCs) are fabricated by coating CdSe QDs on to the TiO2 arrays. After conversion from NRs to NTs, more QDs can be filled in the NTs and the energy conversion efficiency of the QDSCs almost double.

  5. Synthesis and characterization of UV-treated Fe-doped bismuth lanthanum titanate-doped TiO2 layers in dye-sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Song, Myoung Geun; Bark, Chung Wung

    2016-06-01

    Dye-sensitized solar cells (DSSCs) based on titanium dioxide (TiO2) have been extensively studied because they constitute promising low-cost alternatives to their conventional semiconductor-based counterparts. However, much of the effort aimed at achieving high conversion efficiencies has focused on dye and liquid electrolytes. In this work, we report the photovoltaic characteristics of DSSCs fabricated by mixing TiO2 with Fe-doped bismuth lanthanum titanate (Fe-BLT). These nanosized Fe-BLT powders were prepared by using a high-energy ball-milling process. In addition, we used a UV radiation-ozone (UV-O3) treatment to change the surface wettability of TiO2 from hydrophobic to hydrophilic and thereby prevented the easy separation of the Fe-BLT-mixed TiO2 from the fluorine-doped tin-oxide (FTO) coating glass.

  6. Three-dimensional ordered TiO2 hollow spheres as scattering layer in dye-sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Chen, Yang; Chen, Zhigang

    2016-03-01

    TiO2 nanostructure was constructed to obtain an improved photoelectric conversion performance. The design was based on the three-dimensional ordered assembly of TiO2 hollow spheres (3D-TiO2 HPs), which were synthesized using polystyrene colloidal crystals as sacrificial templates. Owing to this highly periodic structure and high specific surface area, the double-layered photoanode films derived from 3D-TiO2 HPs as light scattering layer exhibited enhanced conversion efficiency (7.0 %), thus leading to a 46 % increment of photovoltaic performance compared to the cell based on P25 TiO2 photoanode (4.8 %).

  7. Enhanced photovoltaic performance of inverted hybrid bulk-heterojunction solar cells using TiO2/reduced graphene oxide films as electron transport layers

    NASA Astrophysics Data System (ADS)

    Morais, Andreia; Alves, João Paulo C.; Lima, Francisco Anderson S.; Lira-Cantu, Monica; Nogueira, Ana Flavia

    2015-01-01

    In this study, we investigated inverted hybrid bulk-heterojunction solar cells with the following configuration: fluorine-doped tin oxide (FTO) |TiO2/RGO|P3HT:PC61BM|V2O5 or PEDOT:PSS|Ag. The TiO2/GO dispersions were prepared by sol-gel method, employing titanium isopropoxide and graphene oxide (GO) as starting materials. The GO concentration was varied from 0.1 to 4.0 wt%. The corresponding dispersions were spin-coated onto FTO substrates and a thermal treatment was performed to remove organic materials and to reduce GO to reduced graphene oxide (RGO). The TiO2/RGO films were characterized by x-ray diffraction, Raman spectroscopy, and microscopy techniques. Atomic force microscopy (AFM) images showed that the addition of RGO significantly changes the morphology of the TiO2 films, with loss of uniformity and increase in surface roughness. Independent of the use of V2O5 or PEDOT: PSS films as the hole transport layer, the incorporation of 2.0 wt% of RGO into TiO2 films was the optimal concentration for the best organic photovoltaic performance. The solar cells based on TiO2/RGO (2.0 wt%) electrode exhibited a ˜22.3% and ˜28.9% short circuit current density (Jsc) and a power conversion efficiency enhancement, respectively, if compared with the devices based on pure TiO2 films. Kelvin probe force microscopy images suggest that the incorporation of RGO into TiO2 films can promote the appearance of regions with different charge dissipation capacities.

  8. Photoanode using hollow spherical TiO2 for duel functions in dye-sensitized solar cell.

    PubMed

    Ko, Hwan Ho; Yi, Sung; Jeong, Sung Hoon

    2013-12-01

    We report a new fabrication method of a bilayer photoanode for dye sensitized solar cell having highly crystalline TiO2 with hollow spherical nanoparticles. The hollow spherical TiO2 nanoparticles in DSSC work not only as scattering layer but also as channel of electrolyte. This is due to the fact that incident light is scattered by the hollow spherical nanoparticle according to Mie theory and spherical hollow spheres allow the empty space inside each sphere to circulate the electrolyte more effectively. The nanoparticles were synthesized by hydrothermal method. The space inside the spheres was fully developed by Ostwald Ripening process and the size of hollow spheres was controlled by concentration of PVPs and hydrothermal synthesis conditions (time and temperature). The nanoparticle size and photoanode morphology of the hollow spheres were measured by scanning electron microscope (SEM). Finally, the power conversion efficiency of 6.26% has been achieved under AM 1.5G simulated sunlights (100 mW cm(-2)). PMID:24266162

  9. Home-made experiment of Dye-sensitized TiO2 Nanocrystalline Solar Cells and its education evaluation

    NASA Astrophysics Data System (ADS)

    Tai, M. F.; Shieh, M. C.; Chen, T. W.

    2010-03-01

    Dyes extracted from some natural fruits including anthocyanins absorb sunlight and effectively activate electrons of anthocyanins. Thus these activated electrons are conducted between TiO2 nanocrystals and form electric potential and current between two electrodes. The dyes can be gotten from the natural fruits, such as blackberries, raspberry, pomegranate seeds and bing cherries. This principle permits making a dye sensitized TiO2 nanocrystallines solar cell (DSSC). All required materials and tools for fabricating a home- made DSSC are easy to obtain around home. The procedures are perfect hands-on experiment as well as demonstration in K-12 schools or home settings. We have designed several protocols for fabricating DSSC and have successfully demonstrated in more than 100 activities with different level students. K-12 Students were able to build their own working DSSC's within 2-3 hours sessions and learned about alternative energy sources. These experiments can inspire students and general public about the modern technology in daily life. Low cost (low than US 3 in Taiwan)and safety are also ensured in our DSSC experiments.

  10. Effect of compressed TiO2 nanoparticle thin film thickness on the performance of dye-sensitized solar cells

    PubMed Central

    2013-01-01

    In this study, dye-sensitized solar cells (DSSCs) were fabricated using nanocrystalline titanium dioxide (TiO2) nanoparticles as photoanode. Photoanode thin films were prepared by doctor blading method with 420 kg/cm2 of mechanical compression process and heat treatment in the air at 500°C for 30 min. The optimal thickness of the TiO2 NP photoanode is 26.6 μm with an efficiency of 9.01% under AM 1.5G illumination at 100 mW/cm2. The efficiency is around two times higher than that of conventional DSSCs with an uncompressed photoanode. The open-circuit voltage of DSSCs decreases as the thickness increases. One DSSC (sample D) has the highest conversion efficiency while it has the maximum short-circuit current density. The results indicate that the short-circuit current density is a compromise between two conflict factors: enlargement of the surface area by increasing photoanode thickness and extension of the electron diffusion length to the electrode as the thickness increases. PMID:24192482

  11. Hole-Conductor-Free Mesoscopic TiO2/CH3NH3PbI3 Heterojunction Solar Cells Based on Anatase Nanosheets and Carbon Counter Electrodes.

    PubMed

    Rong, Yaoguang; Ku, Zhiliang; Mei, Anyi; Liu, Tongfa; Xu, Mi; Ko, Songguk; Li, Xiong; Han, Hongwei

    2014-06-19

    A hole-conductor-free fully printable mesoscopic TiO2/CH3NH3PbI3 heterojunction solar cell was developed with TiO2 nanosheets containing high levels of exposed (001) facets. The solar cell embodiment employed a double layer of mesoporous TiO2 and ZrO2 as a scaffold infiltrated by perovskite as a light harvester. No hole conductor or Au reflector was employed. Instead, the back contact was simply a printable carbon layer. The perovskite was infiltrated from solution through the porous carbon layer. The high reactivity of (001) facets in TiO2 nanosheets improved the interfacial properties between the perovskite and the electron collector. As a result, photoelectric conversion efficiency of up to 10.64% was obtained with the hole-conductor-free fully printable mesoscopic TiO2/CH3NH3PbI3 heterojunction solar cell. The advantages of fully printable technology and the use of low-cost carbon-materials-based counter electrode and hole-conductor-free structure provide this design a promising prospect to approach low-cost photovoltaic devices.

  12. One-pot synthesis of peacock-shaped TiO2 light scattering layer with TiO2 nanorods film for dye-sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Kim, Hyun Sik; Kim, Young-Jea; Lee, Wonjoo; Kang, Soon Hyung

    2013-05-01

    A titanium dioxide (TiO2) film, showing distinctive functions and morphology, was prepared using the hydrothermal method by controlling the ratio of HCl:CH3COOH in acidic medium. A one-dimensional (1-D) TiO2 nanorod (NR) film was synthesized with a length of 2 μm using a 1:2 ratio of HCl:CH3COOH, whereas a 1-D TiO2 NR film with peacock shaped TiO2 nanobundles as a light scattering layer (LSL) was acquired by employing a 2:1 ratio of HCl:CH3COOH. This LSL exhibited remarkable dual functions with respect to high light harvesting, which was attributable to the large surface area of the micrometer-sized TiO2 nanobundles, consisting of small-sized TiO2 NRs of 30-40 nm in diameter and a light scattering effect in the long wavelength region of 550-700 nm. Accordingly, the dual functions of the LSL resulted in a sharp increase in conversion efficiency (3.93%) that was about twice that (1.49%) of TiO2 NR film synthesized using a 1:2 ratio of HCl:CH3COOH. In particular, a considerably enhanced short-circuit photocurrent (Jsc) was mainly responsible for the resulting increase in overall efficiency with a moderate increase in fill factor and slightly reduced open-circuit voltage.

  13. TiO2 dye sensitized solar cell (DSSC): linear relationship of maximum power point and anthocyanin concentration

    NASA Astrophysics Data System (ADS)

    Ahmadian, Radin

    2010-09-01

    This study investigated the relationship of anthocyanin concentration from different organic fruit species and output voltage and current in a TiO2 dye-sensitized solar cell (DSSC) and hypothesized that fruits with greater anthocyanin concentration produce higher maximum power point (MPP) which would lead to higher current and voltage. Anthocyanin dye solution was made with crushing of a group of fresh fruits with different anthocyanin content in 2 mL of de-ionized water and filtration. Using these test fruit dyes, multiple DSSCs were assembled such that light enters through the TiO2 side of the cell. The full current-voltage (I-V) co-variations were measured using a 500 Ω potentiometer as a variable load. Point-by point current and voltage data pairs were measured at various incremental resistance values. The maximum power point (MPP) generated by the solar cell was defined as a dependent variable and the anthocyanin concentration in the fruit used in the DSSC as the independent variable. A regression model was used to investigate the linear relationship between study variables. Regression analysis showed a significant linear relationship between MPP and anthocyanin concentration with a p-value of 0.007. Fruits like blueberry and black raspberry with the highest anthocyanin content generated higher MPP. In a DSSC, a linear model may predict MPP based on the anthocyanin concentration. This model is the first step to find organic anthocyanin sources in the nature with the highest dye concentration to generate energy.

  14. Enhanced photoelectric performance of PbS/CdS quantum dot co-sensitized solar cells via hydrogenated TiO2 nanorod arrays.

    PubMed

    Chen, Yanli; Tao, Qiang; Fu, Wuyou; Yang, Haibin; Zhou, Xiaoming; Su, Shi; Ding, Dong; Mu, Yannan; Li, Xue; Li, Minghui

    2014-08-28

    The enhanced photoelectric performance of quantum dot sensitized solar cells via hydrogenated TiO2 is proposed. The best energy conversion efficiency is 1.5 times higher than cells without hydrogen treatment. We demonstrated that introducing oxygen vacancies by hydrogenation is an effective and feasible method for enhanced photoelectric performance.

  15. Electro-spray deposition of a mesoporous TiO2 charge collection layer: toward large scale and continuous production of high efficiency perovskite solar cells.

    PubMed

    Kim, Min-cheol; Kim, Byeong Jo; Yoon, Jungjin; Lee, Jin-wook; Suh, Dongchul; Park, Nam-gyu; Choi, Mansoo; Jung, Hyun Suk

    2015-12-28

    The spin-coating method, which is widely used for thin film device fabrication, is incapable of large-area deposition or being performed continuously. In perovskite hybrid solar cells using CH(3)NH(3)PbI(3) (MAPbI(3)), large-area deposition is essential for their potential use in mass production. Prior to replacing all the spin-coating process for fabrication of perovskite solar cells, herein, a mesoporous TiO(2) electron-collection layer is fabricated by using the electro-spray deposition (ESD) system. Moreover, impedance spectroscopy and transient photocurrent and photovoltage measurements reveal that the electro-sprayed mesoscopic TiO(2) film facilitates charge collection from the perovskite. The series resistance of the perovskite solar cell is also reduced owing to the highly porous nature of, and the low density of point defects in, the film. An optimized power conversion efficiency of 15.11% is achieved under an illumination of 1 sun; this efficiency is higher than that (13.67%) of the perovskite solar cell with the conventional spin-coated TiO(2) films. Furthermore, the large-area coating capability of the ESD process is verified through the coating of uniform 10 × 10 cm(2) TiO(2) films. This study clearly shows that ESD constitutes therefore a viable alternative for the fabrication of high-throughput, large-area perovskite solar cells.

  16. Efficiency enhancement of dye-sensitized solar cells by use of ZrO2-doped TiO2 nanofibers photoanode.

    PubMed

    Mohamed, Ibrahim M A; Dao, Van-Duong; Barakat, Nasser A M; Yasin, Ahmed S; Yousef, Ahmed; Choi, Ho-Suk

    2016-08-15

    Due to the good stability and convenient optical properties, TiO2 nanostructures still the prominent photoanode materials in the Dye Sensitized Solar Cells (DSCs). However, the well-known low bandgap energy and weak adsorption affinity for the dye distinctly constrain the wide application. This work discusses the impact of Zr-doping and nanofibrous morphology on the performance and physicochemical properties of TiO2. Zr-doped TiO2 nanofibers (NFs), with various zirconia content (0, 0.5, 1, 1.5 and 2wt%) were prepared by calcination of electrospun mats composed of polyvinyl acetate, titanium isopropoxyl and zirconium n-propoxyl. For all formulations, the results have shown that the prepared materials are continuous, randomly oriented, and good morphology nanofibers. The average diameter decreased from 353.85nm to 210.78nm after calcination without a considerable influence on the nanofibrous structure regardless the zirconia content. XRD result shows that there is no Rutile nor Brookite phases in the obtained material and the average crystallite size of the sample is affected by the presence of Zr-doping and changed from 23.01nm to 37.63nm for TiO2 and Zr-doped TiO2, respectively. Optical studies have shown Zr-doped TiO2 NFs have more absorbance in the visible region than that of pristine TiO2 NFs; the maximum absorbance is corresponding to the NFs having 1wt% zirconia. The improved spectra of Zr-doped TiO2 in the visible region is attributed to the heterostructure composition resulting from Zr-doping. The absorption bandgaps were calculated using Tauc model as 3.202 and 3.217 for pristine and Zr (1wt%)-doped TiO2 NFs, respectively. Furthermore, in Dye-sensitized Solar Cells, utilizing Zr (1wt%)-doped TiO2 nanofibers achieved higher efficiency of 4.51% compared to the 1.61% obtained from the pristine TiO2 NFs.

  17. Perovskite Solar Cells: Moth-Eye TiO2 Layer for Improving Light Harvesting Efficiency in Perovskite Solar Cells (Small 18/2016).

    PubMed

    Kang, Seong Min; Jang, Segeun; Lee, Jong-Kwon; Yoon, Jungjin; Yoo, Dong-Eun; Lee, Jin-Wook; Choi, Mansoo; Park, Nam-Gyu

    2016-05-01

    A moth-eye patterned mesoporous (mp) TiO2 layer is fabricated in the form of submicron scale by using lithography, nano-imprinting and polydimethyl siloxane (PDMS) stamping methods. On page 2443, M. Choi, N.-G. Park, and co-workers demonstrate an excellent light harvesting property of perovskite solar cell by employing the moth-eye nanostructured mp-TiO2 film. These novel fabrication methods are expected to be optically beneficial to opto-electronic devices. PMID:27151831

  18. CdS/CdSe Co-sensitized Solar Cells Based on Hierarchically Structured SnO2/TiO2 Hybrid Films

    NASA Astrophysics Data System (ADS)

    Chen, Zeng; Wei, Chaochao; Li, Shengjun; Diao, Chunli; Li, Wei; Kong, Wenping; Zhang, Zhenlong; Zhang, Weifeng

    2016-06-01

    SnO2 nanosheet-structured films were prepared on a fluorine-doped tin oxide (FTO) substrate using ZnO nanosheet as template. The as-prepared SnO2 nanosheets contained plenty of nano-voids and were generally vertical to the substrate. TiO2 nanoparticles were homogeneously deposited into the intervals between the SnO2 nanosheets to prepare a hierarchically structured SnO2/TiO2 hybrid film. The hybrid films were co-sensitized with CdS and CdSe quantum dots. The sensitized solar cells assembled with the SnO2/TiO2 hybrid film showed much higher photoelectricity conversion efficiency than the cells assembled with pure TiO2 films. The lifetime of photoinduced electron was also investigated through electrochemical impedance spectroscopy, which showed that the SnO2/TiO2 hybrid film electrode is as long as the TiO2 film electrode.

  19. Combined Embedding of N/F-Doping and CaCO3 Surface Modification in the TiO2 Photoanode for Dye-Sensitized Solar Cells.

    PubMed

    Park, Su Kyung; Yun, Tae Kwan; Bae, Jae Young

    2016-03-01

    N/F-doping and CaCO3 surface modification was carried out in TiO2 photoelectrodes for dye-sensitized solar cells (DSSCs). The combined effect of the N/F doped TiO2 and the CaCO3 coating showed a great increase of the short-circuit current (J(sc)), and photoelectric conversion efficiency (η) of the prepared cells; the efficiency (η) was improved from 7.00% of a commercial TiO2 photoelectrode to 7.90% of an uncoated N/F-doped electrode, and to 9.09% of a N/F-doped and CaCO3 surface modified electrode. An enhanced photoresponse in N/F-doped TiO2 nanoparticles generate more photo-excited electrons, as supported by measured UV-Vis diffuse reflectance spectra. A successive CaCO3 surface modification then forms a barrier on the surface of the N/F-doped TiO2 particles; the higher basicity of the CaCO3 modified TiO2 facilitates the dye adsorption, as supported by the direct measurement of the amount of adsorbed dye.

  20. Influence of PVP template on the formation of porous TiO2 nanofibers by electrospinning technique for dye-sensitized solar cell

    NASA Astrophysics Data System (ADS)

    Elayappan, Vijayakumar; Panneerselvam, Pratheep; Nemala, Sivasankar; Nallathambi, Karthick S.; Angaiah, Subramania

    2015-09-01

    The porous TiO2 nanofibers were prepared by electrospinning technique using polyvinylpyrrolidone (PVP) as template as well as pore-forming agent at the calcination temperature of 475 °C for 5 h. The influence of various concentrations of PVP (5, 8 and 10 wt%) on the surface area and porosity of the prepared TiO2 nanofibers (NFs) were studied by using BET-specific surface area analyzer. The TiO2 NFs obtained by using 5 wt% of PVP had higher surface area and porosity than those obtained by using 8 and 10 wt% of PVP. The prepared electrospun TiO2 NFs were characterized by using TG analysis, X-ray diffraction, FTIR, FE-SEM and TEM studies. Finally, dye-sensitized solar cells were assembled using the prepared TiO2 NFs as the photoanode, Pt as the cathode and 0.5 M 1-butyl-3-methylimidazolium iodide, 0.5 M LiI, 0.05 M I2, 0.5 M 4-tertbutylpyridine in acetonitrile as an electrolyte. Among the three photoanodes, the cell assembled using porous TiO2 NFs obtained by using 5 wt% of PVP showed higher power conversion efficiency (PCE) of 4.81 % than those obtained by using 8 and 10 wt% of PVP, which showed the lower PCE of 4.13 and 3.42 %, respectively.

  1. Combined Embedding of N/F-Doping and CaCO3 Surface Modification in the TiO2 Photoanode for Dye-Sensitized Solar Cells.

    PubMed

    Park, Su Kyung; Yun, Tae Kwan; Bae, Jae Young

    2016-03-01

    N/F-doping and CaCO3 surface modification was carried out in TiO2 photoelectrodes for dye-sensitized solar cells (DSSCs). The combined effect of the N/F doped TiO2 and the CaCO3 coating showed a great increase of the short-circuit current (J(sc)), and photoelectric conversion efficiency (η) of the prepared cells; the efficiency (η) was improved from 7.00% of a commercial TiO2 photoelectrode to 7.90% of an uncoated N/F-doped electrode, and to 9.09% of a N/F-doped and CaCO3 surface modified electrode. An enhanced photoresponse in N/F-doped TiO2 nanoparticles generate more photo-excited electrons, as supported by measured UV-Vis diffuse reflectance spectra. A successive CaCO3 surface modification then forms a barrier on the surface of the N/F-doped TiO2 particles; the higher basicity of the CaCO3 modified TiO2 facilitates the dye adsorption, as supported by the direct measurement of the amount of adsorbed dye. PMID:27455671

  2. Preparation of TiO2 nanowires/nanotubes using polycarbonate membranes and their uses in dye-sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Roh, Dong Kyu; Patel, Rajkumar; Ahn, Sung Hoon; Kim, Dong Jun; Kim, Jong Hak

    2011-10-01

    Track-etched polycarbonate (PC) membranes were used as a soft template to synthesize mesoporous TiO2 for use in dye-sensitized solar cells (DSSCs). The Ti precursor infiltrated into the cylindrical confined spaces of PC membranes. Upon calcination at 500 °C, TiO2 nanowires (15TNW) were obtained from PC with a 15 nm pore diameter, whereas TiO2 nanotubes (50TNT and 100TNT) were generated from PC with 50 and 100 nm diameter pores, respectively. TNW and TNT were used as photoelectrodes in DSSCs employing a polymer electrolyte. The ranking of the cell efficiencies of the 200 nm thick TiO2 films was 50TNT (1.1%) > 15TNW (0.8%) ≅ 100TNT (0.7%), which was mostly attributed to different amounts of dye adsorption due to different surface areas. These TNW and TNT films were further coated with the graft copolymer-directed mesoporous TiO2 and were used as interfacial layers between the FTO glass and the 4 μm thick nanocrystalline TiO2 film. As a result, the order of energy conversion efficiency was 15TNW (5.0%) ≅ 50TNT (4.8%) > 100TNT (4.1%). The improved performance of 15TNW was due to a higher transmittance through the electrode and a longer electron lifetime for recombination. The DSSC performance was systematically investigated in terms of interfacial resistance and charge recombination using electrochemical impedance spectroscopy.

  3. Morphology control studies of TiO2 microstructures via surfactant-assisted hydrothermal process for dye-sensitized solar cell applications

    NASA Astrophysics Data System (ADS)

    Lekphet, Woranan; Ke, Tsai-Chyuan; Su, Chaochin; Kathirvel, Sasipriya; Sireesha, Pedaballi; Akula, Suri Babu; Li, Wen-Ren

    2016-09-01

    The controlled morphological TiO2 particles have gained great importance in a wide variety of applications due to their promising physico-chemical properties. In this study, TiO2 microstructures with various shapes to utilize as scattering layer in dye-sensitized solar cell (DSSC) applications were successfully synthesized via different hydrothermal conditions. The effects of the versatile preparation parameters including the amount of titania precursor and surfactant, the addition of ethanol/water, and the hydrothermal process temperature and time on the TiO2 morphology were investigated. The structural and morphological analysis clearly shown that the preparation conditions played crucial roles in the morphology, particle size, and crystalline phase of the TiO2 microparticles. Different kinds of shapes such as rice- (∼1.10 μm (l) and ∼0.41 μm (w)), star- (∼3.60 μm) and flower-like (3.75 μm) TiO2 morphological structures were obtained. The morphology and size of the TiO2 particles were mainly governed by the concentrations of titanium tetraisopropoxide (TTIP) precursor, amounts of tetramethylammonium hydroxide (TMAH) surfactant and hydrothermal temperatures and durations. The as-prepared rice-shaped TiO2 was composed of mixed anatase and brookite binary phases, whereas the star- and flower-shaped TiO2 microstructures were consisted of ternary anatase, rutile, and brookite crystalline TiO2 phases. The three different rice-, star-, and flower-shaped TiO2 microstructures were employed as scattering layers for photoanodes in DSSCs. Among them, the star-like TiO2 photoanode based DSSC exhibited the highest power conversion efficiency of 9.56%, which was also better than those of the devices fabricated without scattering layer (a-TiO2, 8.38%) and with commercial P25 as scattering layer (a-TiO2/P25-TiO2, 8.52%) at the same film thickness of ∼14 μm.

  4. Analysis of changes in efficiency by simulating dye-sensitized solar cells varying the characteristics of TiO2

    NASA Astrophysics Data System (ADS)

    Gagliardi, Alessio; Gentilini, Desiree; Giordano, Fabrizio; Auf der Maur, Matthias; Di Carlo, Aldo

    2010-02-01

    Dye Sensitized solar cells (DSC) are an interesting alternative to conventional silicon based solar cells. Although DSCs are very close to be commercialized, still many issues need to be addressed. Part of the problem is related to the lack of a reliable and consistent simulator able to catch the physics and the chemistry underlining the functioning of the cell. The need of a reliable simulator and modelling is particularly important for the engineering of the cell and to define trends not only in the component characteristics, but also in the building of the device. Among the different parts which compone a DSC the relevance of semiconductor titanium oxide substrate can hardly be underestimated. TiO2 is where the dye molecule is chemisorbed and where the recombination occurs. Moreover, changes in the topology of the semiconductor paste can lead to other smaller effects in the total efficiency. In this paper we investigate the effects of changing working parameters for the titanium oxide and varying its topology. The simulations are performed using a finite element code based on TiberCAD software1 to describe in details the electrical properties of the cell. The CAD allows to calculate steady-state properties and ideal I-V characteristics of the cell solving a set of differential equations on meshes in 1, 2 and 3 dimensions.

  5. Radio Frequency Magnetron Sputtering Deposition of TiO2 Thin Films and Their Perovskite Solar Cell Applications.

    PubMed

    Chen, Cong; Cheng, Yu; Dai, Qilin; Song, Hongwei

    2015-12-03

    In this work, we report a physical deposition based, compact (cp) layer synthesis for planar heterojunction perovskite solar cells. Typical solution-based synthesis of cp layer for perovskite solar cells involves low-quality of thin films, high-temperature annealing, non-flexible devices, limitation of large-scale production and that the effects of the cp layer on carrier transport have not been fully understood. In this research, using radio frequency magnetron sputtering (RFMS), TiO2 cp layers were fabricated and the thickness could be controlled by deposition time; CH3NH3PbI3 films were prepared by evaporation &immersion (E &I) method, in which PbI2 films made by thermal evaporation technique were immersed in CH3NH3I solution. The devices exhibit power conversion efficiency (PCE) of 12.1% and the photovoltaic performance can maintain 77% of its initial PCE after 1440 h. The method developed in this study has the capability of fabricating large active area devices (40 × 40 mm(2)) showing a promising PCE of 4.8%. Low temperature and flexible devices were realized and a PCE of 8.9% was obtained on the PET/ITO substrates. These approaches could be used in thin film based solar cells which require high-quality films leading to reduced fabrication cost and improved device performance.

  6. Radio Frequency Magnetron Sputtering Deposition of TiO2 Thin Films and Their Perovskite Solar Cell Applications.

    PubMed

    Chen, Cong; Cheng, Yu; Dai, Qilin; Song, Hongwei

    2015-01-01

    In this work, we report a physical deposition based, compact (cp) layer synthesis for planar heterojunction perovskite solar cells. Typical solution-based synthesis of cp layer for perovskite solar cells involves low-quality of thin films, high-temperature annealing, non-flexible devices, limitation of large-scale production and that the effects of the cp layer on carrier transport have not been fully understood. In this research, using radio frequency magnetron sputtering (RFMS), TiO2 cp layers were fabricated and the thickness could be controlled by deposition time; CH3NH3PbI3 films were prepared by evaporation &immersion (E &I) method, in which PbI2 films made by thermal evaporation technique were immersed in CH3NH3I solution. The devices exhibit power conversion efficiency (PCE) of 12.1% and the photovoltaic performance can maintain 77% of its initial PCE after 1440 h. The method developed in this study has the capability of fabricating large active area devices (40 × 40 mm(2)) showing a promising PCE of 4.8%. Low temperature and flexible devices were realized and a PCE of 8.9% was obtained on the PET/ITO substrates. These approaches could be used in thin film based solar cells which require high-quality films leading to reduced fabrication cost and improved device performance. PMID:26631493

  7. Radio Frequency Magnetron Sputtering Deposition of TiO2 Thin Films and Their Perovskite Solar Cell Applications

    PubMed Central

    Chen, Cong; Cheng, Yu; Dai, Qilin; Song, Hongwei

    2015-01-01

    In this work, we report a physical deposition based, compact (cp) layer synthesis for planar heterojunction perovskite solar cells. Typical solution-based synthesis of cp layer for perovskite solar cells involves low-quality of thin films, high-temperature annealing, non-flexible devices, limitation of large-scale production and that the effects of the cp layer on carrier transport have not been fully understood. In this research, using radio frequency magnetron sputtering (RFMS), TiO2 cp layers were fabricated and the thickness could be controlled by deposition time; CH3NH3PbI3 films were prepared by evaporation & immersion (E & I) method, in which PbI2 films made by thermal evaporation technique were immersed in CH3NH3I solution. The devices exhibit power conversion efficiency (PCE) of 12.1% and the photovoltaic performance can maintain 77% of its initial PCE after 1440 h. The method developed in this study has the capability of fabricating large active area devices (40 × 40 mm2) showing a promising PCE of 4.8%. Low temperature and flexible devices were realized and a PCE of 8.9% was obtained on the PET/ITO substrates. These approaches could be used in thin film based solar cells which require high-quality films leading to reduced fabrication cost and improved device performance. PMID:26631493

  8. Photoconversion of Dye-Sensitized Solar Cells with a 3D-Structured Photoelectrode Consisting of Both TiO2 Nanofibers and Nanoparticles

    NASA Astrophysics Data System (ADS)

    Hwang, Tae-Hwan; Kim, Wan-Tae; Choi, Won-Youl

    2016-06-01

    In dye-sensitized solar cells, a three-dimensional (3-D)-structured photoelectrode of TiO2 nanofibers and nanoparticles was successfully fabricated by electro-spinning and screen-printing processes. Structures with one-dimensional nanofibers can be expected to improve the charge transport in a photoelectrode. The microstructure and crystalline structure were observed by field-emission scanning electron microscopy and with an x-ray diffractometer, respectively. The particle size of the TiO2 particles and the diameters of the TiO2 nanofiber in the 3-D-structured photoelectrode were ~30 nm and ~500 nm, respectively. The total thickness of the TiO2 layer in the 3-D-structured photoelectrode, which is composed of a nanoparticle layer of ~12 μm and a nanofiber layer of ~8 μm, was ~20 μm. The crystalline, anatase phase was also determined. In these dye-sensitized solar cells with a 3-D-structured layer, a short-circuit current density of 12.36 mA/cm2, an open-circuit voltage of 0.74 V, a fill factor of 0.46, and an energy conversion efficiency of 4.18% were observed. These values are higher than those of dye-sensitized solar cells with a conventional TiO2 nanoparticle layer. The proposed 3-D-structured photoelectrode consisting of TiO2 nanofibers and nanoparticles can help improve the performance of commercial dye-sensitized solar cells.

  9. Enhanced photoelectrical performance of dye-sensitized solar cells with double-layer TiO2 on perovskite SrTiO3 substrate

    NASA Astrophysics Data System (ADS)

    Liu, Qiuhong; Sun, Qiong; Zhang, Min; Li, Yang; Zhao, Mei; Dong, Lifeng

    2016-04-01

    In this research, perovskite SrTiO3 particles are synthesized by a hydrothermal method, and TiO2 with a double-layer structure is grown on the SrTiO3 surface by a hydrolysis-condensation process. Structural characterizations reveal that TiO2 comprises of two phases: anatase film at the bottom and single-crystal rutile nanorods grown along the [110] direction on top. The TiO2-SrTiO3 composite film is investigated as photoanode material for dye-sensitized solar cells. In comparison with pure TiO2 and SrTiO3, the composite photoanode shows a much better performance in photoelectric conversion efficiency (1.35 %), which is about 2 and 100 times as efficient as pure TiO2 and SrTiO3, respectively. This indicates that the composite structure can facilitate charge carrier transfer and reduce electron-hole recombination to enhance photoelectrical properties of TiO2-based photoanode materials.

  10. A strategy to enhance the efficiency of dye-sensitized solar cells by the highly efficient TiO2/ZnS photoanode.

    PubMed

    Srinivasa Rao, S; Punnoose, Dinah; Venkata Tulasivarma, Ch; Pavan Kumar, C H S S; Gopi, Chandu V V M; Kim, Soo-Kyoung; Kim, Hee-Je

    2015-02-01

    In dye-sensitized solar cells (DSSCs), the TiO2 photoanode film plays an important role in increasing the power conversion efficiency. In this work, TiO2 nanoparticles were first coated on fluorine-doped tin oxide by the doctor-blade method, and then a thin film of zinc sulfide (ZnS) was successfully fabricated on the surface of the TiO2 nanoparticles using the successive ionic layer adsorption and reaction method. The performance of the DSSCs was examined in detail using a cobalt sulfide counter electrode and I(-)/I3(-) electrolyte. X-ray diffraction and energy dispersive X-ray spectroscopy measurements were used to find the composition of the films. Characterization with electrochemical impedance spectroscopy indicated that the recombination rate decreased drastically during the electron transportation. The DSSCs based on ZnS coated TiO2 photoanode achieved a power conversion efficiency of 5.90% under 1 sunlight illumination, which is higher than that of the bare TiO2 photoanode (4.43%). This suggests that the promising ZnS-coated TiO2 nanoparticles accumulate a large number of photo-injected electrons in the conduction band of the photoanode and the N719 dye lowers the recombination of photo-injected electrons with the redox electrolyte. PMID:25556975

  11. A General Method for Preparing Anatase TiO2 Treelike-Nanoarrays on Various Metal Wires for Fiber Dye-Sensitized Solar Cells

    PubMed Central

    Chu, Liang; Li, Luying; Su, Jun; Tu, Fanfan; Liu, Nishuang; Gao, Yihua

    2014-01-01

    Anatase TiO2 tree-like nanoarrays were prepared on various metal wires (Ti, W, Ni, etc.) through one-step facile hydrothermal reaction. The anatase TiO2 tree-like nanoarrays consist of long TiO2 nanowire trunks with direct charge transport channels, and a large number of short TiO2 nanorod branches with large surface areas. Fiber dye-sensitized solar cells (FDSSCs) based on the anatase TiO2 tree-like nanoarrays deposited on Ti wires can achieve outstanding power conversion efficiency (PCE) of 6.32%, while FDSSCs on W wires have lower PCE of 3.24% due to the formation of WO3 layer, which might enhance recombination of charges. When the substrate is changed to a Nicole oxide wire, a novel p-n heterojunction can be obtained. This universal method is simple, facile, and low cost for preparing anatase TiO2 treelike-nanoarrays on various metal wires, which may find potential applications in fabrication of optoelectronic devices. PMID:24646952

  12. Double-layer electrode based on TiO2 nanotubes arrays for enhancing photovoltaic properties in dye-sensitized solar cells.

    PubMed

    He, Zuoli; Que, Wenxiu; Sun, Peng; Ren, Jiangbo

    2013-12-26

    The present work reports a rapid and facile method to fabricate a novel double-layer TiO2 photoanode, which is based on highly ordered TiO2 nanotube arrays and monodispersive scattering microspheres. This double-layer TiO2 sphere/TNTA photoanode have got many unique structural and optical properties from TiO2 scattering microspheres, such as high specific surface area, multiple interparticle scattering, and efficient light-harvesting. Results indicate that this as-fabricated double-layer TiO2 sphere/TNTA front-illumination dye-sensitized solar cell, which is fabricated from the TiO2 nanotube arrays with a 17.4 μm length after TiCl4 treatment, exhibits a pronounced power conversion efficiency of 7.24% under an AM1.5 G irradiation, which can be attributed to the increased incident photon-to-current conversion and light-harvesting efficiency. PMID:24304127

  13. An upconversion NaYF4:Yb3+,Er3+/TiO2 core-shell nanoparticle photoelectrode for improved efficiencies of dye-sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Zhang, Jun; Shen, Haiou; Guo, Wei; Wang, Shunhao; Zhu, Chuntao; Xue, Fang; Hou, Jinfeng; Su, Haiquan; Yuan, Zhuobin

    2013-03-01

    Novel upconversion NaYF4:Yb3+,Er3+/TiO2 core-shell nanoparticles (NPs) are synthesized and used to prepare the photoelectrode (PE) of dye-sensitized solar cells (DSSCs). The morphology, structure, photoluminescence characterization of the NaYF4:Yb3+,Er3+/TiO2 core-shell NPs and the photoelectric performance, alternating current impedance spectroscopy of DSSCs are characterized using transmission electron microscopy, X-ray diffraction, upconversion luminescence (UCL) spectrofluorimetry and electrochemistry. Compared with the pure TiO2 PE or the NaYF4:Yb3+,Er3+ upconversion NPs and TiO2 simply mixed prepared PE as the volume ratio of the core-shell structure, the DSSCs with the upconversion core-shell PE show a greater photovoltaic efficiency. The energy conversion efficiency of the DSSCs with a NaYF4:Yb3+,Er3+/TiO2 PE is 23.1% higher than with a pure TiO2 PE and 99.1% higher than with a mixed PE using the same conditions. This enhancement is due to the UCL core extending the spectral response range of DSSCs to the infrared region and their particular shell structure, retaining its semiconductor character. This method represents a novel approach to increase the efficiencies of DSSCs.

  14. Correction: Dye adsorption mechanisms in TiO2 films, and their effects on the photodynamic and photovoltaic properties in dye-sensitized solar cells.

    PubMed

    Hwang, Kyung-Jun; Shim, Wang-Geun; Kim, Dajung; An, Jongdeok; Im, Chan; Kim, Youngjin; Kim, Gunwoo; Choi, Chulmin; Kang, Sang Ook; Cho, Dae Won

    2016-02-21

    Correction for 'Dye adsorption mechanisms in TiO2 films, and their effects on the photodynamic and photovoltaic properties in dye-sensitized solar cells' by Kyung-Jun Hwang et al., Phys. Chem. Chem. Phys., 2015, 17, 21974-21981.

  15. Conveniently fabricated heterojunction ZnO/TiO2 electrodes using TiO2 nanotube arrays for dye-sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Liu, Rui; Yang, Wein-Duo; Qiang, Liang-Sheng; Liu, Hsin-Yi

    2012-12-01

    TiO2 nanotube arrays with an inner average pore diameter of 83 nm and a length of 14 μm are grown on Ti foils by electrochemical anodization in ammonium fluoride-water-glycerol solution. ZnO is introduced into the TiO2 nanotube arrays by a convenient electrodeposition technique. ZnO/TiO2 nanocomposites supported on Ti substrate are used as the photo-anode electrode for dye-sensitized solar cells (DSSCs). The morphology, structure and electrochemical properties are investigated using field-emission scanning electron microscopy, transmission electron microscopy, X-ray diffraction, UV-vis diffusion reflection spectroscopy, X-ray photoelectron spectroscopy and cyclic voltammetry measurements. It is found that ZnO have been embedded in the TiO2 nanotube arrays, and changed some photoelectric properties. The conversion efficiency of the dye-sensitized solar cells is more than doubled, compared with that of bare TiO2 nanotube arrays with deposited 60 min. This improvement comes from the synergetic effect between ZnO and TiO2, which increases dye absorption, electron transport and electron lifetime.

  16. In situ processed gold nanoparticle-embedded TiO2 nanofibers enabling plasmonic perovskite solar cells to exceed 14% conversion efficiency

    NASA Astrophysics Data System (ADS)

    Mali, Sawanta S.; Shim, Chang Su; Kim, Hyungjin; Patil, Pramod S.; Hong, Chang Kook

    2016-01-01

    We have demonstrated organometallic perovskite solar cells (PSCs) based on Au decorated TiO2 nanofibers and methylammonium lead iodide (MAPbI3). A power conversion efficiency of 14.92% was achieved, which is significantly higher than that of conventional mesoporous (mp) TiO2, as well as TiO2 nanofiber-based devices. The present synthetic process provides new opportunities for the development of efficient plasmonic PSCs based on metal oxide nanofibers. Solar cells based on these architectures exhibit a short-circuit current density JSC of 21.63 +/- 0.36 mA cm-2, VOC of 0.986 +/- 0.01 V and fill factor of 70% +/- 3%, which provide a power conversion efficiency of 14.92% +/- 0.33% under standard AM 1.5 conditions. The results of time-resolved photoluminescence (TRPL) spectroscopy and solid-state impedance spectroscopy (ssIS) revealed that PSCs based on Au-decorated TiO2 nanofibers exhibit a low recombination rate. The present results are much higher than those for reported PSCs based on a Au@TiO2 electron-transporting layer (ETL).We have demonstrated organometallic perovskite solar cells (PSCs) based on Au decorated TiO2 nanofibers and methylammonium lead iodide (MAPbI3). A power conversion efficiency of 14.92% was achieved, which is significantly higher than that of conventional mesoporous (mp) TiO2, as well as TiO2 nanofiber-based devices. The present synthetic process provides new opportunities for the development of efficient plasmonic PSCs based on metal oxide nanofibers. Solar cells based on these architectures exhibit a short-circuit current density JSC of 21.63 +/- 0.36 mA cm-2, VOC of 0.986 +/- 0.01 V and fill factor of 70% +/- 3%, which provide a power conversion efficiency of 14.92% +/- 0.33% under standard AM 1.5 conditions. The results of time-resolved photoluminescence (TRPL) spectroscopy and solid-state impedance spectroscopy (ssIS) revealed that PSCs based on Au-decorated TiO2 nanofibers exhibit a low recombination rate. The present results are much

  17. Hyperbranched anatase TiO2 nanocrystals: nonaqueous synthesis, growth mechanism, and exploitation in dye-sensitized solar cells.

    PubMed

    Buonsanti, Raffaella; Carlino, Elvio; Giannini, Cinzia; Altamura, Davide; De Marco, Luisa; Giannuzzi, Roberto; Manca, Michele; Gigli, Giuseppe; Cozzoli, P Davide

    2011-11-30

    A colloidal crystal-splitting growth regime has been accessed, in which TiO(2) nanocrystals, selectively trapped in the metastable anatase phase, can evolve to anisotropic shapes with tunable hyperbranched topologies over a broad size interval. The synthetic strategy relies on a nonaqueous sol-gel route involving programmed activation of aminolysis and pyrolysis of titanium carboxylate complexes in hot surfactant media via a simple multi-injection reactant delivery technique. Detailed investigations indicate that the branched objects initially formed upon the aminolysis reaction possess a strained monocrystalline skeleton, while their corresponding larger derivatives grown in the subsequent pyrolysis stage accommodate additional arms crystallographically decoupled from the lattice underneath. The complex evolution of the nanoarchitectures is rationalized within the frame of complementary mechanistic arguments. Thermodynamic pathways, determined by the shape-directing effect of the anatase structure and free-energy changes accompanying branching and anisotropic development, are considered to interplay with kinetic processes, related to diffusion-limited, spatially inhomogeneous monomer fluxes, lattice symmetry breaking at transient Ti(5)O(5) domains, and surfactant-induced stabilization. Finally, as a proof of functionality, the fabrication of dye-sensitized solar cells based on thin-film photoelectrodes that incorporate networked branched nanocrystals with intact crystal structure and geometric features is demonstrated. An energy conversion efficiency of 6.2% has been achieved with standard device configuration, which significantly overcomes the best performance ever approached with previously documented prototypes of split TiO(2) nanostructures. Analysis of the relevant photovoltaic parameters reveals that the utilized branched building blocks indeed offer light-harvesting and charge-collecting properties that can overwhelm detrimental electron losses due to

  18. Fe-ions implantation to modify TiO2 trilayer films for dye-sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Luo, Jun; Pang, Pan; Liao, Bin; Xianying, Wu; Zhang, Xu

    2016-06-01

    A series of Fe-doped TiO2 trilayer films were prepared successfully by using the ion-implantation technique. The aim of the ion implantation was to enhance charge transfer and to reduce charge recombination. A maximum conversion efficiency of 4.86% was achieved in cells using Fe-ion-implanted electrodes with the illumination of 6×1015 atom/cm2. It is 14.1% higher than that of the cells without ion implantations. The significant improvement in conversion efficiency by Fe-ion implantation could be contributed to the enhancement of dye uptake and charge transfer, as indicated from the incident photon-to-collected electron conversion efficiency and ultraviolet-visible measurements. Furthermore, the implanted Fe-ions introduce impurity levels in the bandgap of TiO2, and this improves the electron injection efficiency from lowest unoccupied molecular orbital of excited N719 into the conduction band of TiO2.

  19. Designing nanostructured one-dimensional TiO2 nanotube and TiO2 nanoparticle multilayer composite film as photoanode in dye-sensitized solar cells to increase the charge collection efficiency

    NASA Astrophysics Data System (ADS)

    Akilavasan, Jeganathan; Al-Jassim, Maufick; Bandara, Jayasundera

    2015-01-01

    A photoanode consisting of hydrothermally synthesized TiO2 nanotubes (TNT) and TiO2 nanoparticles (TNP) was designed for efficient charge collection in dye-sensitized solar cells. TNT and TNP films were fabricated on a conductive glass substrate by using electrophoretic deposition and doctor-blade methods, respectively. The TNP, TNT, and TNT/TNP bi-layer electrodes exhibit solar cell efficiencies of 5.3, 7.4, and 9.2%, respectively. Solar cell performance results indicate a higher short-circuit current density (Jsc) for the TNT/TNP bi-layer electrode when compared to a TNT or TNP electrode alone. The open-circuit voltages (Voc) of TNT/TNP and TNT electrodes are comparable while the Voc of TNP electrode is inferior to that of the TNT/TNP electrode. Fill factors of TNT/TNP, TNT, and TNP electrodes also exhibit similar behaviors. The enhanced efficiency of the TNT/TNP bi-layer electrode is found to be mainly due to the enhancement of charge collection efficiency, which is confirmed by the charge transport parameters measured by electrochemical impedance spectroscopy (EIS). EIS analyses also revealed that the TNT/TNP incurs smaller charge transport resistances and longer electron life times when compared to those of TNT or TNP electrodes alone. It was demonstrated that the TNT/TNP bi-layer electrode can possess the advantages of both rapid electron transport rate and a high light scattering effect.

  20. Photoelectrochemical cell/dye-sensitized solar cell tandem water splitting systems with transparent and vertically aligned quantum dot sensitized TiO2 nanorod arrays

    NASA Astrophysics Data System (ADS)

    Shin, Kahee; Yoo, Ji-Beom; Park, Jong Hyeok

    2013-03-01

    The present work reports fabrication of vertically aligned CdS sensitized TiO2 nanorod arrays grown on transparent conducting oxide substrate with high transparency as a photoanode in photoelectrochemical cell for water splitting. To realize an unassisted water splitting system, the photoanode and dye-sensitized solar cell tandem structures are tried and their electrochemical behaviors are also investigated. The hydrothermally grown TiO2 nanorod arrays followed by CdS nanoparticle decoration can improve the light absorption of long wavelength light resulting in increased photocurrent density. Two different techniques (electrodeposition and spray pyrolysis deposition) of CdS nanoparticle sensitization are carried out and their water splitting behaviors in the tandem cell are compared.

  1. The effect of optical properties on photovoltaic performance in dye-sensitized TiO2 nanocrystalline solar cells.

    PubMed

    Ji, Ya-Jun; Zhang, Ming-Dao; Cui, Jie-Hu; Zheng, He-Gen; Zhu, Jun-Jie

    2013-06-01

    In this study, well-crystallized TiO2 nanoparticles with average size of -20 nm were synthesized by hydrolysis of titania salt in aqueous medium. The effect of the optical properties of the obtained titania particles based thin films with different thickness on the photovoltaic performance of dye-sensitized solar cells were investigated. Differential thermal analysis/thermo-gravimetric analysis, scanning electron microscopy, transmission electron microscopy and X-ray diffraction were used to characterize the morphology, structure and crystal formation of the obtained samples. The optical properties such as reflectance and transmittance of the photoanodes with different thickness were systematically investigated. The reflectance property increased with increasing the film thickness, however, the transmittance property showed the opposite way. The improved scattering property with increasing the film thickness facilitated efficient utilization of solar spectrum, which was verified by incident photon-to-current conversion efficiency. The maximum energy conversion efficiency of 5.0% was achieved on photoelectrode film with 17.8 microm.

  2. Wet chemical synthesis and self-assembly of SnS2 nanoparticles on TiO2 for quantum dot-sensitized solar cells.

    PubMed

    Tsukigase, Hiroki; Suzuki, Yoshikazu; Berger, Marie-Hélène; Sagawa, Takashi; Yoshikawa, Susumu

    2011-04-01

    SnS2 nanoparticles were synthesized through a simple wet chemical process at room temperature. The SnS2 nanoparticles were approximately spherical in shape and had diameter about 3-4 nm. SnS2-sensitized TiO2 electrodes were fabricated by the immersion of chemically modified TiO2 to well-dispersed SnS2 solution for 72 h (i.e., self-assembly method.) SnS2-sensitized TiO2 electrodes were applied in quantum dot-sensitized solar cells (QDSSCs). Under AM1.5 irradiation with 100 mW/cm2 light intensity (at 1 sun), the short-circuit current density (J(sc)), the open-circuit voltage (V(oc)), the fill factor (FF), and the energy conversion efficiency (eta) were 0.47 mA/cm2, 0.29 V, 0.58 and 0.081%, respectively.

  3. Fine Tuning of Nanocrystal and Pore Sizes of TiO2 Submicrospheres toward High Performance Dye-Sensitized Solar Cells.

    PubMed

    Li, Zhao-Qian; Ding, Yong; Mo, Li-E; Hu, Lin-Hua; Wu, Ji-Huai; Dai, Song-Yuan

    2015-10-14

    In general, the properties and performance of mesoporous TiO2 are greatly dependent on its crystal size, crystallinity, porosity, surface area, and morphology; in this regard, design and fine-tuning the crystal and pore sizes of the TiO2 submicrospheres and investigating the effect of these factors on the properties and photoelectric performance of dye-sensitized solar cells (DSSCs) is essential. In this work, uniform TiO2 submicrospheres were synthesized by a two-step procedure containing hydrolysis and solvothermal process. The crystal and pore sizes of the TiO2 submicrospheres were fine-tuned and controlled in a narrow range by adjusting the quantity of NH4OH during the solvothermal process. The effect of crystal and pore size of TiO2 submicrosphere on the performance of the DSSCs and their properties including dye-loading capacity, light scattering effect, power conversion efficiency (PCE), incident photon-to-electron conversion efficiencies (IPCEs), and electron recombination were compared and analyzed. The results show that increasing pore size plays a more significant role in improving the dye-loading capacity and PCE than increasing surface area, and an overall PCE value of 8.62% was obtained for the device with a 7.0 μm film thickness based on the TiO2 submicrospheres treated with 0.6 mL of NH4OH. Finally, the best TiO2 submicrosphere based photoanode film was optimized by TiCl4 treatment, and increasing film thickness and a remarkable PCE up to 11.11% were achieved.

  4. Enhanced photovoltaic performance of fully flexible dye-sensitized solar cells based on the Nb2O5 coated hierarchical TiO2 nanowire-nanosheet arrays

    NASA Astrophysics Data System (ADS)

    Liu, Wenwu; Hong, Chengxun; Wang, Hui-gang; Zhang, Mei; Guo, Min

    2016-02-01

    Nb2O5 coated hierarchical TiO2 nanowire-sheet arrays photoanode was synthesized on flexible Ti-mesh substrate by using a hydrothermal approach. The effect of TiO2 morphology and Nb2O5 coating layer on the photovoltaic performance of the flexible dye sensitized solar cells (DSSCs) based on Ti-mesh supported nanostructures were systematically investigated. Compared to the TiO2 nanowire arrays (NWAs), hierarchical TiO2 nanowire arrays (HNWAs) with enlarged internal surface area and strong light scattering properties exhibited higher overall conversion efficiency. The introduction of thin Nb2O5 coating layers on the surface of the TiO2 HNWAs played a key role in improving the photovoltaic performance of the flexible DSSC. By separating the TiO2 and electrolyte (I-/I3-), the Nb2O5 energy barrier decreased the electron recombination rate and increased electron collection efficiency and injection efficiency, resulting in improved Jsc and Voc. Furthermore, the influence of Nb2O5 coating amounts on the power conversion efficiency were discussed in detail. The fully flexible DSSC based on Nb2O5 coated TiO2 HNWAs films with a thickness of 14 μm displayed a well photovoltaic property of 4.55% (Jsc = 10.50 mA cm-2, Voc = 0.75 V, FF = 0.58). The performance enhancement of the flexible DSSC is largely attributed to the reduced electron recombination, enlarged internal surface area and superior light scattering ability of the formed hierarchical nanostructures.

  5. Graphene oxide nanosheets as an effective template for the synthesis of porous TiO2 film in dye-sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Wang, Ping; He, Fenglong; Wang, Jin; Yu, Huogen; Zhao, Li

    2015-12-01

    Template method by using various organic components as the pore-forming agent is an effective strategy for the preparation of various porous inorganic materials. After high-temperature calcination in air, the organic components can be in situ decomposed into the gaseous CO2, resulting in the formation of porous structures in inorganic materials. In addition to the well-known organic components, it is highly required to develop new and simple carbon-containing template to prepare porous inorganic nanostructures. In this study, graphene oxide (GO) nanosheets were used as a new template for the preparation of porous TiO2 film photoelectrode, which can be applied in dye-sensitized solar cells (DSSCs). The porous TiO2 film was fabricated via a three-step method, including the initially homogeneous grafting of GO nanosheets on the TiO2 surface (TiO2-GO), the preparation of TiO2-GO film using blade method and final formation of porous structure after the in situ removal of GO by high-temperature calcination. The effect of GO content on photoelectric conversion performance of the as-fabricated DSSCs was investigated. It was found that the conversion efficiency of DSSC based on porous TiO2-GO (0.75%) film reached up to a maximum value (4.65%), which was much higher than that of DSSC based on nonporous TiO2 film (4.01%). The enhanced conversion efficiency can be attributed to the formation of more porous structures caused by the GO nanosheets after high-temperature calcination. This work may provide a new insight for preparing other porous structured materials.

  6. Nitrogen doped TiO2-Cu(x)O core-shell mesoporous spherical hybrids for high-performance dye-sensitized solar cells.

    PubMed

    Guo, Enyan; Yin, Longwei

    2015-01-01

    We report on high-performance dye-sensitized solar cells (DSSCs) based on nitrogen doped anatase TiO2-CuxO core-shell mesoporous hybrids synthesized through a facile and controlled combined sol-gel and hydrothermal process in the presence of hexadecylamine as the structure-directing agent. The matching of band edges between CuxO and TiO2 to form a semiconductor heterojunction plays an important role in effective separation of light induced electrons and holes, providing a promising photoanode for DSSCs because of its wide absorption spectrum, high electron injection efficiency, and fast electron transference. DSSCs based on the mesoporous TiO2-CuxO core-shell hybrids show a high short-circuit current density of 9.60 mA cm(-2) and a conversion efficiency of 3.86% under one sun illumination. While DSSCs based on the N-doped mesoporous TiO2-CuxO hybrids exhibit the higher short-circuit current density of 13.24 mA cm(-2) and a conversion efficiency of 4.57% under one sun illumination. In comparison with un-doped TiO2-CuxO hybrids, the doping of nitrogen into the lattice of TiO2 can extend the light absorption in the ultraviolet range to the visible light region and effectively decrease the recombination rate of photo-generated electrons and holes. The presented N-doped mesoporous TiO2-CuxO hybrids as photoanodes could find potential applications for high performance DSSCs.

  7. Fine Tuning of Nanocrystal and Pore Sizes of TiO2 Submicrospheres toward High Performance Dye-Sensitized Solar Cells.

    PubMed

    Li, Zhao-Qian; Ding, Yong; Mo, Li-E; Hu, Lin-Hua; Wu, Ji-Huai; Dai, Song-Yuan

    2015-10-14

    In general, the properties and performance of mesoporous TiO2 are greatly dependent on its crystal size, crystallinity, porosity, surface area, and morphology; in this regard, design and fine-tuning the crystal and pore sizes of the TiO2 submicrospheres and investigating the effect of these factors on the properties and photoelectric performance of dye-sensitized solar cells (DSSCs) is essential. In this work, uniform TiO2 submicrospheres were synthesized by a two-step procedure containing hydrolysis and solvothermal process. The crystal and pore sizes of the TiO2 submicrospheres were fine-tuned and controlled in a narrow range by adjusting the quantity of NH4OH during the solvothermal process. The effect of crystal and pore size of TiO2 submicrosphere on the performance of the DSSCs and their properties including dye-loading capacity, light scattering effect, power conversion efficiency (PCE), incident photon-to-electron conversion efficiencies (IPCEs), and electron recombination were compared and analyzed. The results show that increasing pore size plays a more significant role in improving the dye-loading capacity and PCE than increasing surface area, and an overall PCE value of 8.62% was obtained for the device with a 7.0 μm film thickness based on the TiO2 submicrospheres treated with 0.6 mL of NH4OH. Finally, the best TiO2 submicrosphere based photoanode film was optimized by TiCl4 treatment, and increasing film thickness and a remarkable PCE up to 11.11% were achieved. PMID:26393366

  8. Aqueous-phase linker-assisted attachment of cysteinate(2-)-capped cdse quantum dots to TiO2 for quantum dot-sensitized solar cells.

    PubMed

    Coughlin, Kathleen M; Nevins, Jeremy S; Watson, David F

    2013-09-11

    We have synthesized water-dispersible cysteinate(2-)-capped CdSe nanocrystals and attached them to TiO2 using one-step linker-assisted assembly. Room-temperature syntheses yielded CdSe magic-sized clusters (MSCs) exhibiting a narrow and intense first excitonic absorption band centered at 422 nm. Syntheses at 80 °C yielded regular CdSe quantum dots (RQDs) with broader and red-shifted first excitonic absorption bands. Cysteinate(2-)-capped CdSe MSCs and RQDs adsorbed to bare nanocrystalline TiO2 films from aqueous dispersions. CdSe-functionalized TiO2 films were incorporated into working electrodes of quantum dot-sensitized solar cells (QDSSCs). Short-circuit photocurrent action spectra of QDSSCs corresponded closely to absorptance spectra of CdSe-functionalized TiO2 films. Power-conversion efficiencies were (0.43±0.04)% for MSC-functionalized TiO2 and (0.83±0.11)% for RQD-functionalized TiO2. Absorbed photon-to-current efficiencies under white-light illumination were approximately 0.3 for both MSC- and RQD-based QDSSCs, despite the significant differences in the electronic properties of MSCs and RQDs. Cysteinate(2-) is an attractive capping group and ligand, as it engenders water-dispersibility of CdSe nanocrystals with a range of photophysical properties, enables facile all-aqueous linker-assisted attachment of nanocrystals to TiO2, and promotes efficient interfacial charge transfer.

  9. Fabrication and characterization of a nanostructured TiO2/In2S3-Sb2S3/CuSCN extremely thin absorber (eta) solar cell

    NASA Astrophysics Data System (ADS)

    Huerta-Flores, Alí M.; García-Gómez, Nora A.; de la Parra-Arciniega, Salomé M.; Sánchez, Eduardo M.

    2016-08-01

    In this work we report the successful assembly and characterization of a TiO2/In2S3-Sb2S3/CuSCN extremely thin absorber solar cell. Nanostructured TiO2 deposited by screen printing on an ITO substrate was used as an n-type electrode. An ∼80 nm extremely thin layer of the system In2S3-Sb2S3 deposited by successive ionic layer adsorption and a reaction (silar) method was used as an absorber. The voids were filled with p-type CuSCN and the entire assembly was completed with a gold contact. The solar cell fabricated with this heterostructure showed an energy conversion efficiency of 4.9%, which is a promising result in the development of low cost and simple fabrication of solar cells.

  10. Dye-sensitized solar cells employing a single film of mesoporous TiO2 beads achieve power conversion efficiencies over 10%.

    PubMed

    Sauvage, Frédéric; Chen, Dehong; Comte, Pascal; Huang, Fuzhi; Heiniger, Leo-Philipp; Cheng, Yi-Bing; Caruso, Rachel A; Graetzel, Michael

    2010-08-24

    Dye-sensitized solar cells employing mesoporous TiO(2) beads have demonstrated longer electron diffusion lengths and extended electron lifetimes over Degussa P25 titania electrodes due to the well interconnected, densely packed nanocrystalline TiO(2) particles inside the beads. Careful selection of the dye to match the dye photon absorption characteristics with the light scattering properties of the beads have improved the light harvesting and conversion efficiency of the bead electrode in the dye-sensitized solar cell. This has resulted in a solar to electric power conversion efficiency (PCE) of greater than 10% (10.6% for Ru(II)-based dye C101 and 10.7% using C106) for the first time using a single screen-printed titania layer cell construction (that is, without an additional scattering layer).

  11. Bilayer film electrode of brookite TiO2 particles with different morphology to improve the performance of pure brookite-based dye-sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Xu, Jinlei; Wu, Shufang; Ri, Jin Hyok; Jin, Jingpeng; Peng, Tianyou

    2016-09-01

    A novel bilayer brookite TiO2 film photoanode consisting of quasi nanocube film as underlayer and rice-like submicrometer particle film as overlayer are fabricated for improving the photovoltaic properties of the pure brookite-based dye-sensitized solar cells (DSSCs). The brookite TiO2 nanocubes have a mean size of ∼50 nm, and the brookite TiO2 rice-like particles have diameter of ∼600 nm and length of ∼1100 nm. An optimal photovoltaic conversion efficiency of 5.51% is obtained from the bilayer brookite-based solar cell, with ∼41% improvement in the efficiency as compared to the single brookite nanocube film-based one (3.91%) under AM 1.5G one sun irradiation. The bilayer brookite-based solar cell shows not only reduced charge recombination and dark current, but also prolonged electron lifetime compared to the single brookite nanocube film-based one. All these lead to a higher photocurrent and voltage, and then to the improved efficiency of the brookite-based solar cell. The present results demonstrate a clear advance towards efficient improvement of the photovoltaic performance of pure brookite-based solar cells.

  12. TiO2 film decorated with highly dispersed polyoxometalate nanoparticles synthesized by micelle directed method for the efficiency enhancement of dye-sensitized solar cells

    NASA Astrophysics Data System (ADS)

    He, Lifei; Chen, Li; Zhao, Yue; Chen, Weilin; Shan, Chunhui; Su, Zhongmin; Wang, Enbo

    2016-10-01

    In this work, two kinds of polyoxometalate (POM) nanoparticles with controlled shapes and structures were synthesized by micelle directed method and then composited with TiO2 via calcination to remove the surfactants owing to the excellent electronic storage and transmission ability of POM, finally obtaining two kinds of TiO2 composites with highly dispersed and small-sized POM nanoparticles (∼1 nm). The TiO2 composites were then induced into the photoanodes of dye-sensitized (N719) solar cells (DSSCs). The separation of electron-holes becomes more favorable due to the nanostructure and high dispersion of POM which provide more active sites than pure POM tending to agglomeration. The TiO2 composite photoanodes finally yielded the power conversion efficiency (PCE) of 8.4% and 8.2%, respectively, which were 42% and 39% higher than the pristine TiO2 based anodes. In addition, the mechanisms of POM in DSSC are proposed.

  13. Effect of Nb-doped TiO2 on nanocomposited aligned ZnO nanorod/TiO2:Nb for dye-sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Saurdi, I.; Shafura, A. K.; Azhar, N. E. A.; Ishak, A.; Malek, M. F.; Alrokayan, A. H. Salman; Khan, Haseeb A.; Mamat, M. H.; Rusop, M.

    2016-07-01

    The Nb-doped TiO2 films were deposited on glass substrate at different Nb concentrations of 0 at.%, 1 at.%, 3 at.%, 5 at.% and 7 at.%, respectively and their electrical and structural properties were investigated. Subsequently, the Nb-doped TiO2 films were deposited on top of aligned ZnO Nanorod on ITO glass substrates using spin coating technique. The nanocomposited aligned ZnO nanorod/Nb-doped TiO2 (TiO2:Nb) were coated with different Nb concentrations of 0 at.%, 1 at.%, 3 at.%, 5 at.% and 7 at.%, respectively. The Dye-sensitized solar cells were fabricated from the nanocomposited aligned ZnO nanorod/TiO2:Nb photoanodes and their effects on the performance of the DSSCs were investigated. From the solar simulator measurement of DSSC the solar energy conversion efficiency (η) of 5.376% under AM 1.5 was obtained for the ZnO nanorod/TiO2:Nb-5at.%.

  14. Design of Ag@C@SnO2@TiO2 yolk-shell nanospheres with enhanced photoelectric properties for dye sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Zhao, Peilu; Li, Dan; Yao, Shiting; Zhang, Yiqun; Liu, Fengmin; Sun, Peng; Chuai, Xiaohong; Gao, Yuan; Lu, Geyu

    2016-06-01

    The hierarchical Ag@C@SnO2@TiO2 nanospheres (ACSTS) have been successfully synthesized by deposition of SnO2 and TiO2 on the Ag@C templates layer by layer. The size of ACSTS is ca. 360 nm while the Ag@C cores have an average diameter of about 300 nm. The rough and porous shell structure consisting of SnO2 and TiO2 ensures a large specific surface area (115.5 m2 g-1). To demonstrate how such a unique structure might lead to more excellent photovoltaic property, several kinds of dye-sensitized solar cells (DSSCs) are also fabricated using different nanospheres based photoanodes. It is found that the ACSTS based DSSC exhibits an obvious improvement in cell performance. According to various technical characterization, the ACSTS can provide dual-functions of light absorption and charge transfer, hence resulting in an enhanced short-circuit photocurrent density of 18.68 mA cm-2 and a higher FF of 63% compared with other DSSCs. The ACSTS cell finally obtains a PCE of up to 8.62%, increasing by 70.4% and 10.2% than hollow TiO2 nanospheres and Ag@C@TiO2 nanospheres based cells, respectively. The improved photovoltaic properties of ACSTS cell can be mainly ascribed to the unique microstructure and the synergistic effect of the encapsulated Ag@C cores.

  15. Anatase TiO2 nanowires functionalized by organic sensitizers for solar cells: A screened Coulomb hybrid density functional study

    NASA Astrophysics Data System (ADS)

    Ünal, Hatice; Gunceler, Deniz; Gülseren, Oǧuz; Ellialtioǧlu, Şinasi; Mete, Ersen

    2015-11-01

    The adsorption of two different organic molecules cyanidin glucoside (C21O11H20) and TA-St-CA on anatase (101) and (001) nanowires has been investigated using the standard and the range separated hybrid density functional theory calculations. The electronic structures and optical spectra of resulting dye-nanowire combined systems show distinct features for these types of photochromophores. The lowest unoccupied molecular orbital of the natural dye cyanidin glucoside is located below the conduction band of the semiconductor while, in the case of TA-St-CA, it resonates with the states inside the conduction band. The wide-bandgap anatase nanowires can be functionalized for solar cells through electron-hole generation and subsequent charge injection by these dye sensitizers. The intermolecular charge transfer character of Donor-π-Acceptor type dye TA-St-CA is substantially modified by its adsorption on TiO2 surfaces. Cyanidin glucoside exhibits relatively stronger anchoring on the nanowires through its hydroxyl groups. The atomic structures of dye-nanowire systems re-optimized with the inclusion of nonlinear solvation effects showed that the binding strengths of both dyes remain moderate even in ionic solutions.

  16. Anatase mesoporous TiO2 nanofibers with high surface area for solid-state dye-sensitized solar cells.

    PubMed

    Zhang, Wei; Zhu, Rui; Ke, Lin; Liu, Xizhe; Liu, Bin; Ramakrishna, Seeram

    2010-10-01

    Mesoporous nanofibers (NFs) with a high surface area of 112 m(2)/g have been prepared by electrospinning technique. The structures of mesoporous NFs and regular NFs are characterized and compared through scanning electron microscope (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD) and selected area electron diffraction (SAED) studies. Using mesoporous TiO(2) NFs as the photoelectrode, solid-state dye-sensitized solar cells (SDSCs) have been fabricated employing D131 as the sensitizer and P3HT as the hole transporting material to yield an energy conversion efficiency (η) of 1.82%. A J(sc) of 3.979 mA cm(-2) is obtained for mesoporous NF-based devices, which is 3-fold higher than that (0.973 mA cm(-2)) for regular NF-based devices fabricated under the same condition (η = 0.42%). Incident photon-to-current conversion efficiency (IPCE) and dye-desorption test demonstrate that the increase in J(sc) is mainly due to greatly improved dye adsorption for mesoporous NFs as compared to that for regular NFs. In addition, intensity modulated photocurrent spectroscopy (IMPS) and intensity modulated photovoltage spectroscopy (IMVS) measurements indicate that the mesopores on NF surface have very minor effects on charge transport and collection. Initial aging test proves good stability of the fabricated devices, which indicates the promise of mesoporous NFs as photoelectrode for low-cost SDSCs.

  17. An easy-to-fabricate low-temperature TiO2 electron collection layer for high efficiency planar heterojunction perovskite solar cells

    NASA Astrophysics Data System (ADS)

    Conings, B.; Baeten, L.; Jacobs, T.; Dera, R.; D'Haen, J.; Manca, J.; Boyen, H.-G.

    2014-08-01

    Organometal trihalide perovskite solar cells arguably represent the most auspicious new photovoltaic technology so far, as they possess an astonishing combination of properties. The impressive and brisk advances achieved so far bring forth highly efficient and solution processable solar cells, holding great promise to grow into a mature technology that is ready to be embedded on a large scale. However, the vast majority of state-of-the-art perovskite solar cells contains a dense TiO2 electron collection layer that requires a high temperature treatment (>450 °C), which obstructs the road towards roll-to-roll processing on flexible foils that can withstand no more than ˜150 °C. Furthermore, this high temperature treatment leads to an overall increased energy payback time and cumulative energy demand for this emerging photovoltaic technology. Here we present the implementation of an alternative TiO2 layer formed from an easily prepared nanoparticle dispersion, with annealing needs well within reach of roll-to-roll processing, making this technology also appealing from the energy payback aspect. Chemical and morphological analysis allows to understand and optimize the processing conditions of the TiO2 layer, finally resulting in a maximum obtained efficiency of 13.6% for a planar heterojunction solar cell within an ITO/TiO2/CH3NH3PbI3-xClxpoly(3-hexylthiophene)/Ag architecture.

  18. Double-sided brush-shaped TiO2 nanostructure assemblies with highly ordered nanowires for dye-sensitized solar cells.

    PubMed

    Zha, Chenyang; Shen, Liming; Zhang, Xiaoyan; Wang, Yifeng; Korgel, Brian A; Gupta, Arunava; Bao, Ningzhong

    2014-01-01

    We describe a seeded hydrothermal process for the growth of unique double-sided brush-shaped (DSBS) TiO2 nanostructure assemblies consisting of highly ordered rutile nanowires vertically aligned around an annealed TiO2 nanoparticle layer. The annealed TiO2 nanoparticle layer seeds the nanowire growth and also supports the DSBS structure. The morphology of the DSBS TiO2 nanostructure depends on the hydrothermal reaction time. The diameter of the nanowires is about 6.6 nm, and with increasing reaction time from 1 to 8 h the nanowire length increases from 0.6 to 6.2 μm, whereas the thickness of the nanoparticle layer decreases from 4.3 to 2.8 μm. These free-standing nanowire arrays provide large internal surface area, which is essential for minimizing carrier recombination in high performance photovoltaic devices. Furthermore, the nanowire architecture can help increase the rate of charge transport as compared to particulate films because of lower concentration of grain boundaries. The power conversion efficiency of backside (DSBS TiO2/FTO photoanode) illuminated dye-sensitized solar cells fabricated using the DSBS TiO2 nanostructure assembly is found to be depended on the nanowire length. A cell fabricated using 15.2 μm thick nanostructures sensitized by N719 has a short-circuit current density of 12.18 mA cm(-2), 0.78 V open circuit potential, and a 0.59 filling factor, yielding a maximum power conversion efficiency of 5.61% under AM 1.5 illumination.

  19. Improved performance of dye sensitized solar cells using Cu-doped TiO2 as photoanode materials: Band edge movement study by spectroelectrochemistry

    NASA Astrophysics Data System (ADS)

    Zhou, Li; Wei, Liguo; Yang, Yulin; Xia, Xue; Wang, Ping; Yu, Jia; Luan, Tianzhu

    2016-08-01

    Cu-doped TiO2 nanoparticles are prepared and used as semiconductor materials of photoanode to improve the performance of dye sensitized solar cells (DSSCs). UV-Vis spectroscopy and variable temperature spectroelectrochemistry study are used to characterize the influence of copper dopant with different concentrations on the band gap energies of TiO2 nanoparticles. The prepared Cu-doped TiO2 semiconductor has avoided the formation of CuO during hydrothermal process and lowered the conduction band position of TiO2, which contribute to increase the short circuit current density of DSSCs. At the optimum Cu concentration of 1.0 at.%, the short circuit current density increased from 12.54 to 14.98 mA cm-2, full sun solar power conversion efficiencies increased from 5.58% up to 6.71% as compared to the blank DSSC. This showed that the presence of copper in DSSCs leads to improvements of up to 20% in the conversion efficiency of DSSCs.

  20. D-sorbitol-induced phase control of TiO2 nanoparticles and its application for dye-sensitized solar cells.

    PubMed

    Shaikh, Shoyebmohamad F; Mane, Rajaram S; Min, Byoung Koun; Hwang, Yun Jeong; Joo, Oh-shim

    2016-02-09

    Using a simple hydrothermal synthesis, the crystal structure of TiO2 nanoparticles was controlled from rutile to anatase using a sugar alcohol, D-sorbitol. Adding small amounts of D-sorbitol to an aqueous TiCl4 solution resulted in changes in the crystal phase, particle size, and surface area by affecting the hydrolysis rate of TiCl4. These changes led to improvements of the solar-to-electrical power conversion efficiency (η) of dye-sensitized solar cells (DSSC) fabricated using these nanoparticles. A postulated reaction mechanism concerning the role of D-sorbitol in the formation of rutile and anatase was proposed. Fourier-transform infrared spectroscopy, (13)C NMR spectroscopy, and dynamic light scattering analyses were used to better understand the interaction between the Ti precursor and D-sorbitol. The crystal phase and size of the synthesized TiO2 nanocrystallites as well as photovoltaic performance of the DSSC were examined using X-ray diffraction, Raman spectroscopy, field-emission scanning electron microscopy, high-resolution transmission electron microscopy, and photocurrent density-applied voltage spectroscopy measurement techniques. The DSSC fabricated using the anatase TiO2 nanoparticles synthesized in the presence of D-sorbitol, exhibited an enhanced η (6%, 1.5-fold improvement) compared with the device fabricated using the rutile TiO2 synthesized without D-sorbitol.

  1. D-sorbitol-induced phase control of TiO2 nanoparticles and its application for dye-sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Shaikh, Shoyebmohamad F.; Mane, Rajaram S.; Min, Byoung Koun; Hwang, Yun Jeong; Joo, Oh-Shim

    2016-02-01

    Using a simple hydrothermal synthesis, the crystal structure of TiO2 nanoparticles was controlled from rutile to anatase using a sugar alcohol, D-sorbitol. Adding small amounts of D-sorbitol to an aqueous TiCl4 solution resulted in changes in the crystal phase, particle size, and surface area by affecting the hydrolysis rate of TiCl4. These changes led to improvements of the solar-to-electrical power conversion efficiency (η) of dye-sensitized solar cells (DSSC) fabricated using these nanoparticles. A postulated reaction mechanism concerning the role of D-sorbitol in the formation of rutile and anatase was proposed. Fourier-transform infrared spectroscopy, 13C NMR spectroscopy, and dynamic light scattering analyses were used to better understand the interaction between the Ti precursor and D-sorbitol. The crystal phase and size of the synthesized TiO2 nanocrystallites as well as photovoltaic performance of the DSSC were examined using X-ray diffraction, Raman spectroscopy, field-emission scanning electron microscopy, high-resolution transmission electron microscopy, and photocurrent density-applied voltage spectroscopy measurement techniques. The DSSC fabricated using the anatase TiO2 nanoparticles synthesized in the presence of D-sorbitol, exhibited an enhanced η (6%, 1.5-fold improvement) compared with the device fabricated using the rutile TiO2 synthesized without D-sorbitol.

  2. D-sorbitol-induced phase control of TiO2 nanoparticles and its application for dye-sensitized solar cells

    PubMed Central

    Shaikh, Shoyebmohamad F.; Mane, Rajaram S.; Min, Byoung Koun; Hwang, Yun Jeong; Joo, Oh-shim

    2016-01-01

    Using a simple hydrothermal synthesis, the crystal structure of TiO2 nanoparticles was controlled from rutile to anatase using a sugar alcohol, D-sorbitol. Adding small amounts of D-sorbitol to an aqueous TiCl4 solution resulted in changes in the crystal phase, particle size, and surface area by affecting the hydrolysis rate of TiCl4. These changes led to improvements of the solar-to-electrical power conversion efficiency (η) of dye-sensitized solar cells (DSSC) fabricated using these nanoparticles. A postulated reaction mechanism concerning the role of D-sorbitol in the formation of rutile and anatase was proposed. Fourier-transform infrared spectroscopy, 13C NMR spectroscopy, and dynamic light scattering analyses were used to better understand the interaction between the Ti precursor and D-sorbitol. The crystal phase and size of the synthesized TiO2 nanocrystallites as well as photovoltaic performance of the DSSC were examined using X-ray diffraction, Raman spectroscopy, field-emission scanning electron microscopy, high-resolution transmission electron microscopy, and photocurrent density-applied voltage spectroscopy measurement techniques. The DSSC fabricated using the anatase TiO2 nanoparticles synthesized in the presence of D-sorbitol, exhibited an enhanced η (6%, 1.5-fold improvement) compared with the device fabricated using the rutile TiO2 synthesized without D-sorbitol. PMID:26857963

  3. Transparent, 3-dimensional light-collected, and flexible fiber-type dye-sensitized solar cells based on highly ordered hierarchical anatase TiO2 nanorod arrays

    NASA Astrophysics Data System (ADS)

    Liang, Jia; Zhang, Gengmin; Yin, Jianbo; Yang, Yingchao

    2014-12-01

    Two kinds of hierarchical anatase TiO2 structures are synthesized by a facile hydrothermal method in this report. A new transparent, 3D light-collected, and flexible fiber-type dye-sensitized solar cell (FF-DSSC) with such hierarchical TiO2 structures is developed. The conversion efficiency of the FF-DSSC based on a TiCl4-treated TiO2 nanorod array (hierarchical structure I) exhibits about 4 times higher than that based on a HCl-treated TiO2 nanorod array, and further rises to 4.4% when the TiCl4-treated TiO2 nanorod array is treated in a mixed solution of (NH4)2TiF6 and H3BO3 three times (hierarchical structure II). The obvious enhancement in conversion efficiency can be ascribed to the dye adsorption promotion benefiting from their hierarchical structures. Beyond the attractive conversion efficiency, the new designed FF-DSSC possesses several advantages including good flexibility, excellent stability, and 3D light-collection. The conversion efficiencies of the FF-DSSCs can still keep 85%-90% even the FF-DSSCs are bent for 1000 times. The maximum power outputs of the FF-DSSCs characterized by Diffuse Illumination Mode using home-made Al reflector exhibit about 3 times higher than that done by Standard Illumination Mode due to 3D light-collections. The FF-DSSCs based on highly ordered hierarchical anatase TiO2 nanorod arrays hold great promise in future energy harvest.

  4. A SnOx-brookite TiO2 bilayer electron collector for hysteresis-less high efficiency plastic perovskite solar cells fabricated at low process temperature.

    PubMed

    Kogo, Atsushi; Ikegami, Masashi; Miyasaka, Tsutomu

    2016-06-21

    Thin plastic film-based CH3NH3PbI3-xClx perovskite solar cells were fabricated at low process temperature using a bilayer comprising an amorphous SnOx and mesoporous brookite TiO2 as electron collectors. Void-less high quality heterojunction structures achieve hysteresis-less photovoltaic performance with a power conversion efficiency as high as 13.4% and mechanical stability against cyclic bending.

  5. Core/Shell Structured TiO2/CdS Electrode to Enhance the Light Stability of Perovskite Solar Cells.

    PubMed

    Hwang, Insung; Baek, Minki; Yong, Kijung

    2015-12-23

    In this work, enhanced light stability of perovskite solar cell (PSC) achieved by the introduction of a core/shell-structured CdS/TiO2 electrode and the related mechanism are reported. By a simple solution-based process (SILAR), a uniform CdS shell was coated onto the surface of a TiO2 layer, suppressing the activation of intrinsic trap sites originating from the oxygen vacancies of the TiO2 layer. As a result, the proposed CdS-PSC exhibited highly improved light stability, maintaining nearly 80% of the initial efficiency after 12 h of full sunlight illumination. From the X-ray diffraction analyses, it is suggested that the degradation of the efficiency of PSC during illumination occurs regardless of the decomposition of the perovskite absorber. Considering the light-soaking profiles of the encapsulated cells and the OCVD characteristics, it is likely that the CdS shell had efficiently suppressed the undesirable electron kinetics, such as trapping at the surface defects of the TiO2 and preventing the resultant charge losses by recombination. This study suggests that further complementary research on various effective methods for passivation of the TiO2 layer would be highly meaningful, leading to insight into the fabrication of PSCs stable to UV-light for a long time.

  6. Effect of Cu2O Doping in TiO2 Films on Device Performance of Dye-Sensitized Solar Cells

    NASA Astrophysics Data System (ADS)

    Koo, Horng-Show; Wang, Der-Tsuey; Yu, Yi-Kuei; Ho, Shao-Hung; Jhang, Jia-Yu; Chen, Mi; Tai, Ming-Fong

    2012-10-01

    We demonstrated the effects of Cu2O doping at various weight ratios in TiO2 photoanode films on the photovoltaic performance of dye-sensitized solar cells (DSSCs). The photovoltaic characteristics, namely, open-circuit voltage, short-circuit current, fill factor, and energy conversion efficiency, of DSSCs with 0.3 wt % Cu2O doping in the photoanode are 690 mV, 4.55 mA/cm2, 52.0%, and 1.96%, respectively. The photovoltaic parameters of the sample with 0.3 wt % Cu2O doping are better than those of other Cu2O-doped samples, which are inferior to undoped TiO2-based DSSCs. The measured cell performance shows that the addition of Cu2O to the TiO2 photoanode in DSSCs results in the reduction of photovoltaic parameters. The degradation mechanism upon Cu2O doping in the TiO2 photoanode of DSSCs may be attributed to the variations in the valence numbers of copper and titanium ions during calcination and the reduction-oxidation reaction, resulting in the formation of oxygen vacancy-Ti+3 defects and related recombination centers.

  7. PbS Quantum Dots Sensitized TiO2 Solar Cells Prepared by Successive Ionic Layer Absorption and Reaction with Different Adsorption Layers.

    PubMed

    Yi, Jie; Duan, Yanfang; Liu, Chunxia; Gao, Shaohong; Han, Xueting; An, Limin

    2016-04-01

    Lead sulfide (PbS) quantum dots (QDs) have been synthesized via successive ionic layer adsorption and reaction (SILAR) on a titanium dioxide (TiO2) nanoporous film for the fabrication of quantum dot-sensitized solar cells (QDSCs). The reaction is environmental friendly and energy saving. The green synthesized PbS QDs match the maximum remittance region of the solar spectrum and are suitable as sensitizers for TiO2 electrodes for cell devices application. PbS QDs were adsorbed in different adsorption layers in order to improve the solar cell performance. The optical properties of PbS sensitized TiO2 films were studied by scanning electron microscopy and UV-Vis absorbance spectroscopy. The photovoltaic characteristics of the PbS QDSCs were analyzed by I-V characteristics and electrochemical impedance spectroscopy. As a result, the light harvesting was enhanced with increasing SILAR adsorption layers. The maximum photovoltaic conversion efficiency of the PbS QDSCs (3.14%) was obtained at the 12 adsorption layers with the highest short circuit current density and lowest charge transfer resistance. PMID:27451735

  8. Absorption enhancement in CH3NH3PbI3 solar cell using a TiO2/MoS2 nanocomposite electron selective contact

    NASA Astrophysics Data System (ADS)

    Imran Ahmed, Muhammad; Hussain, Zakir; Khalid, Amir; Noman Amin, Hafiz Muhammad; Habib, Amir

    2016-04-01

    In the present contribution, perovskite absorbers have been combined with few layer thick MoS2 semiconductor to put together a solar cell allowing broad spectrum harvesting of solar radiations. Such modification allows to achieve solar light harvesting at the band edges, addressing a drawback of CH3NH3PbI3 absorbers. We recorded an improved efficiency from 3.7% to 4.3% on the back of this methodology. We have also worked out a novel methodology to synthesize TiO2/MoS2 nanocomposite by in situ dispersion of liquid exfoliated MoS2 sheets in the sol gel reaction.

  9. Rose Bengal sensitized bilayered photoanode of nano-crystalline TiO2-CeO2 for dye-sensitized solar cell application

    NASA Astrophysics Data System (ADS)

    Sayyed, Suhail A. A. R.; Beedri, Niyamat I.; Kadam, Vishal S.; Pathan, Habib M.

    2016-08-01

    The present work deals with the study of TiO2-CeO2 bilayered photoanode with low-cost Rose Bengal (RB) dye as sensitizer for dye-sensitized solar cell application. The recombination reactions are reduced in bilayered TiO2-CeO2 photoanode as compared to the single-layered CeO2 photoanode. Once the electrons get transferred from lowest unoccupied molecular orbital level of RB dye to the conduction band (CB) of TiO2, then the possibilities of recombination of electrons with oxidized dye molecules or oxidized redox couple are reduced. This is because the CB position of CeO2 is higher than that of TiO2, which blocks the path of electrons. The electrochemical impedance spectroscopy (EIS) analysis shows negative shift in frequency for bilayered TiO2-CeO2 photoanode as compared to CeO2 photoanode. Hence, in bilayered photoanode lifetime of electrons is more than in single-layered photoanode, confirming reduction in recombination reactions. The X-ray diffraction patterns confirm both anatase TiO2 and CeO2 with crystalline size using Scherrer formula as 24 and 10 nm, respectively. The scanning electron microscopy images of photoanode show the porous structure useful for dye adsorption. The presence of Ti and Ce is confirmed by electron diffraction studies. The band gap values for TiO2 and CeO2 were calculated as 3.20 and 3.11 eV, respectively, using diffused reflectance spectroscopy. The bilayered TiO2-CeO2 photoanode showed open-circuit voltage ( V OC) ~500 mV and short-circuit photocurrent density ( J SC) ~0.29 mA/cm2 with fill factor (FF) ~62.17 %. There is increase in V OC and J SC values by 66.67 and 38.10 %, respectively, compared to RB-sensitized CeO2 photoanode.

  10. Synthesis of CdSe -- TiO2 Nanocomposites and Their Applications to TiO2 Sensitized Solar Cells

    SciTech Connect

    Kim, J. Y.; Choi, S. B.; Noh, J. H.; HunYoon, S.; Lee, S.; Noh, T. H.; Frank, A. J.; Hong, K. S.

    2009-01-01

    CdSe-TiO{sub 2} nanocomposites were synthesized via aminolysis of Ti-oleate complexes in the presence of CdSe nanocrystals, and their application as sensitizers for TiO{sub 2} solar cells was investigated. The formation of CdSe-TiO{sub 2} nanocomposites was confirmed using transmission electron microscopy and Raman spectroscopy. The emission spectrum of CdSe-TiO{sub 2} nanocomposites revealed photoinduced charge separation at the CdSe-TiO{sub 2} interface of the composite. The photocurrent-voltage properties of CdSe-TiO{sub 2}-sensitized TiO{sub 2} particle films compared favorably with those of CdSe-sensitized TiO{sub 2} films. Evidence was also found indicating that the TiO{sub 2} component of the composite protects CdSe against degradation during film annealing.

  11. g-C3N4 modified TiO2 nanosheets with enhanced photoelectric conversion efficiency in dye-sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Xu, Jian; Wang, Guanxi; Fan, Jiajie; Liu, Baoshun; Cao, Shaowen; Yu, Jiaguo

    2015-01-01

    Dye-sensitized solar cells (DSSCs) were fabricated by using g-C3N4 modified TiO2 nanosheets (CTS) as photoanode materials in this research. A thin layer of g-C3N4 was coated on the surface of TiO2 nanosheets by simply heating the mixture of TiO2 nanosheets and urea, which led to the formation of TiO2@g-C3N4 nanosheet heterostructure. The experimental results showed that the photoelectric conversion efficiency of DSSCs was obviously improved after modified by g-C3N4. The measurements of I-V characteristic indicated that the introduction of g-C3N4 could increase both the open circuit voltage and short-circuit photocurrent density. Along with the analysis of electrochemical impedance spectroscopy, it is considered that the thin layer of g-C3N4 can act as the blocking layer for electron backward recombination with electrolyte, which can be used as the functional material to increase the DSSC performance.

  12. Extremely enhanced photovoltaic properties of dye-sensitized solar cells by sintering mesoporous TiO2 photoanodes with crystalline titania chelated by acetic acid

    NASA Astrophysics Data System (ADS)

    Liu, Bo-Tau; Chou, Ya-Hui; Liu, Jin-Yan

    2016-04-01

    The study presents a significant improvement on the performance of dye-sensitized solar cells (DSSCs) through incorporating the crystalline titania chelated by acetic acid (TAc) into the mesoporous TiO2 photoanodes. The effects of TAc on the blocking layer, mesoporous TiO2 layer, and post-treatment have been investigated. The TAc blocking layer displays compact construction, revealing superior response time and resistance to suppress dark current compared to the blocking layer made from titanium(IV) isopropoxide (TTIP). The power conversion efficiency of DSSCs with the TAc treatment can reach as high as 10.49%, which is much higher than that of pristine DSSCs (5.67%) and that of DSSCs treated by TTIP (7.86%). We find that the TAc incorporation can lead to the decrease of charge transfer resistance and the increase of dye adsorption. The result may be attributed to the fact that the TAc possesses high crystallinity, exposed (101) planes, and acid groups chelated on surface, which are favorable for dye attachment and strong bonding at the FTO/TiO2 and the TiO2/TiO2 interfaces, These improvements result in the remarkable increase of photocurrent and thereby that of power conversion efficiency.

  13. Effects of size-controlled TiO2 nanopowders synthesized by chemical vapor condensation process on conversion efficiency of dye-sensitized solar cells.

    PubMed

    Kim, Woo-Byoung; Lee, Jai-Sung

    2013-07-01

    To investigate the microstructural effects of the synthesized TiO2 nanopowders such as particle size, specific surface area, pore size and pore distributions for the application of an anode material of dye-sensitized solar cells (DSSC), size-controlled and well-dispersed TiO2 nanopowders were synthesized by chemical vapor condensation (CVC) process in the range of 800-1000 degreesC under a pressure of 50 mbar. The average particle size of synthesized TiO2 nanopowders was increased with increasing temperature from 13 nm for 800 degreesC, 15 nm for 900 degreesC and 26 nm. The specific surface area of synthesized nanoparticles were measured as 119.1 m2/g for 800 degreesC, 104.7 m2/g for 900 degreesC and 59.5 m2/g for 1000 degreesC, respectively. The conversion efficiency values (eta%) of DSSC with the synthesized TiO2 nanopowders at 800 degreesC, 900 degreesC, and 1000 degreesC were 2.59%, 5.96% and 3.66%, respectively. The highest conversion efficiency obtained in the 900 degreesC (5.96%) sample is thought to be attributable to homogeneous particle size and pore distributions, large specific surface area, and high transmittance in regions of dye absorption wavelength.

  14. Efficient Performance of Electrostatic Spray-Deposited TiO2 Blocking Layers in Dye-Sensitized Solar Cells after Swift Heavy Ion Beam Irradiation.

    PubMed

    Sudhagar, P; Asokan, K; Jung, June Hyuk; Lee, Yong-Gun; Park, Suil; Kang, Yong Soo

    2011-12-01

    A compact TiO2 layer (~1.1 μm) prepared by electrostatic spray deposition (ESD) and swift heavy ion beam (SHI) irradiation using oxygen ions onto a fluorinated tin oxide (FTO) conducting substrate showed enhancement of photovoltaic performance in dye-sensitized solar cells (DSSCs). The short circuit current density (Jsc = 12.2 mA cm(-2)) of DSSCs was found to increase significantly when an ESD technique was applied for fabrication of the TiO2 blocking layer, compared to a conventional spin-coated layer (Jsc = 8.9 mA cm(-2)). When SHI irradiation of oxygen ions of fluence 1 × 10(13) ions/cm(2) was carried out on the ESD TiO2, it was found that the energy conversion efficiency improved mainly due to the increase in open circuit voltage of DSSCs. This increased energy conversion efficiency seems to be associated with improved electronic energy transfer by increasing the densification of the blocking layer and improving the adhesion between the blocking layer and the FTO substrate. The adhesion results from instantaneous local melting of the TiO2 particles. An increase in the electron transport from the blocking layer may also retard the electron recombination process due to the oxidized species present in the electrolyte. These findings from novel treatments using ESD and SHI irradiation techniques may provide a new tool to improve the photovoltaic performance of DSSCs.

  15. Preparation and characterization of TiO2 anode film with spinodal phase separation structure in dye-sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Guli, Mina; Yao, Jianxi; Zhao, Jingyong; Rao, Wangping; Xiao, Li; Tian, Hongxin

    2013-10-01

    Low electronic transmission efficiency and high charge recombination are the existing problems of photoanode film in traditional dye sensitized solar cells (DSSCs). This paper put forward the photoanode TiO2 films with spinodal phase separation structure (SPSS) and continuous TiO2 skeleton which were triggered by the photopolymerization of organic monomers in a photomonomer-inorganic precursor system. The photoanode TiO2 films fabricated by different precursor solution compositions and different coating layers were characterized mainly by scanning electron microscopy (SEM), photocatalysis and photoelectric performance test. The results indicated that, the as-prepared TiO2 anode film with seven coating layers and heat treated at 500 °C showed higher photoelectric conversion efficiency at about 2% than that of other samples with less coating layers and lower heat treatment temperature. The film also showed excellent photocatalytic activity by using methylene blue (MB) dye as a model organic substrate under fluorescent lamp irradiation. It is suggested that the film with SPSS structure has the potential to improve the electronic transmission efficiency and reduce the carrier recombination due to its particular structure, higher surface area, and lack of bottleneck in electronic transmission. It is worth noting that the SPSS structure provides new ideas to develop new photoanode films and further improve the photoelectric conversion performance of the DSSC in future.

  16. Surface Modification of TiO2 Photoanodes with Fluorinated Self-Assembled Monolayers for Highly Efficient Dye-Sensitized Solar Cells.

    PubMed

    Wooh, Sanghyuk; Kim, Tea-Yon; Song, Donghoon; Lee, Yong-Gun; Lee, Tae Kyung; Bergmann, Victor W; Weber, Stefan A L; Bisquert, Juan; Kang, Yong Soo; Char, Kookheon

    2015-11-25

    Dye aggregation and electron recombination in TiO2 photoanodes are the two major phenomena lowering the energy conversion efficiency of dye-sensitized solar cells (DSCs). Herein, we introduce a novel surface modification strategy of TiO2 photoanodes by the fluorinated self-assembled monolayer (F-SAM) formation with 1H,1H,2H,2H-perfluorooctyltriethoxysilane (PFTS), blocking the vacant sites of the TiO2 surface after dye adsorption. The F-SAM helps to efficiently lower the surface tension, resulting in efficient repelling ions, e.g., I3(-), in the electrolyte to decrease the electron recombination rate, and the role of F-SAM is characterized in detail by impedance spectroscopy using a diffusion-recombination model. In addition, the dye aggregates on the TiO2 surface are relaxed by the F-SAM with large conformational perturbation (i.e., helix structure) seemingly because of steric hindrance developed during the SAM formation. Such multifunctional effects suppress the electron recombination as well as the intermolecular interactions of dye aggregates without the loss of adsorbed dyes, enhancing both the photocurrent density (11.9 → 13.5 mA cm(-2)) and open-circuit voltage (0.67 → 0.72 V). Moreover, the combined surface modification with the F-SAM and the classical coadsorbent further improves the photovoltaic performance in DSCs. PMID:26506252

  17. Fabrication N, F, and N/F-Doped TiO2 Photoelectrodes for Dye-Sensitized Solar Cells.

    PubMed

    Park, Su Kyung; Yun, Tae Kwan; Bae, Jae Young

    2015-08-01

    In this study, pure TiO2, N-doped TiO2, F-doped TiO2, and N/F-doped TiO2 particles were successfully synthesized through the hydrolysis of TiCl4 in the presence of ammonia water and NH4F, respectively. The introduction of doping materials did not affect the crystalline structure. No absorption peak for pure TiO2 was observed above the wavelength of 400 nm. However, the N-doped TiO2 and N/F-doped TiO2 powders exhibited a new absorption peak in the visible light region between 400 and 530 nm. The Jsc value of DSSCs based on the N/F-doped TiO2 electrode was increased by 10% compared to DSSCs using a pure TiO2 electrode, and the energy conversion efficiency was increased by 12%.

  18. Callindra haematocephata and Peltophorum pterocarpum flowers as natural sensitizers for TiO2 thin film based dye-sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Maurya, Ishwar Chandra; Neetu; Gupta, Arun Kumar; Srivastava, Pankaj; Bahadur, Lal

    2016-10-01

    We have studied the performance of dye-sensitized solar cells employing natural dye extracted from the flowers Callindra haematocephata and Peltophorum pterocarpum as sensitizers for TiO2 photoanode. The extracts have shown appreciable absorption in the visible region. FTIR studies indicated the presence of anthocyanins and β-carotene in the flowers of C. haematocephata and P. pterocarpum respectively. The extracts were anchored on TiO2 film deposited on transparent conductive glass (FTO) which were used as photoanode. The dye coated TiO2 film electrode, Pt counter electrode and electrolyte (I-3) assembled into a cell module was illuminated by a light source with intensity 100 mW/cm2 to measure the photoelectric conversion efficiency of the DSSCs. From the J-V characteristic curves of cells, the parameters related to the solar cell performance were determined. The conversion efficiency of the DSSC employing natural dye extract from the flower C. haematocephata and P. pterocarpumwere was found as 0.06% and 0.04%, with open-circuit voltage (VOC) of 370 mV & 400 mV, short-circuit current density (JSC) of 0.25 mA/cm2 & 0.15 mA/cm2, fill factor (FF) of 0.70 & 0.71 and Pmax of 65 & 45 μW cm-2 respectively. The extract of the flower C. haematocephata exhibited better photosensitization action compared to the flower of P. pterocarpum.

  19. Microsphere assembly of TiO2 mesoporous nanosheets with highly exposed (101) facets and application in a light-trapping quasi-solid-state dye-sensitized solar cell

    NASA Astrophysics Data System (ADS)

    Tao, Xiyun; Ruan, Peng; Zhang, Xiang; Sun, Hongxia; Zhou, Xingfu

    2015-02-01

    The morphology of nano-titania has a significant effect on the photoelectric properties of dye-sensitized solar cells. In this study, microsphere assembly of a TiO2 mesoporous nanosheet constructed by nanocuboids was conducted via a simple hydrothermal process. The XRD pattern indicated that the hierarchical mesoporous microspheres are anatase phase with decreased (004) peaks. Raman spectrum shows enhanced Eg peaks at 143 and 638 cm-1 caused by the symmetric stretching vibration of O-Ti-O of the (101) crystalline facet in anatase TiO2. FESEM and TEM images show that well monodispersed TiO2 microspheres with a diameter of 2 μm are assembled by TiO2 mesoporous nanosheets with exposed (101) facets. The oriented attachment of TiO2 nanocuboids along the (101) direction leads to the formation of mesoporous titania nanosheets. The UV-Vis spectrum shows that the mesoporous TiO2 nanosheets have high scattering ability and light absorption by dye. Quasi-solid-state dye-sensitized solar cells that incorporate these microspheres into the top scattering layers exhibit a prominent improvement in the power conversion efficiency of 7.51%, which shows a 45.8% increase in the overall conversion efficiency when compared with the spine hierarchical TiO2 microspheres (5.15%). There is the potential application for microsphere assembly of mesoporous TiO2 nanosheets in quasi-solid-state dye-sensitized solar cells with excellent stability.

  20. Microsphere assembly of TiO2 mesoporous nanosheets with highly exposed (101) facets and application in a light-trapping quasi-solid-state dye-sensitized solar cell.

    PubMed

    Tao, Xiyun; Ruan, Peng; Zhang, Xiang; Sun, Hongxia; Zhou, Xingfu

    2015-02-28

    The morphology of nano-titania has a significant effect on the photoelectric properties of dye-sensitized solar cells. In this study, microsphere assembly of a TiO2 mesoporous nanosheet constructed by nanocuboids was conducted via a simple hydrothermal process. The XRD pattern indicated that the hierarchical mesoporous microspheres are anatase phase with decreased (004) peaks. Raman spectrum shows enhanced Eg peaks at 143 and 638 cm(-1) caused by the symmetric stretching vibration of O-Ti-O of the (101) crystalline facet in anatase TiO2. FESEM and TEM images show that well monodispersed TiO2 microspheres with a diameter of 2 μm are assembled by TiO2 mesoporous nanosheets with exposed (101) facets. The oriented attachment of TiO2 nanocuboids along the (101) direction leads to the formation of mesoporous titania nanosheets. The UV-Vis spectrum shows that the mesoporous TiO2 nanosheets have high scattering ability and light absorption by dye. Quasi-solid-state dye-sensitized solar cells that incorporate these microspheres into the top scattering layers exhibit a prominent improvement in the power conversion efficiency of 7.51%, which shows a 45.8% increase in the overall conversion efficiency when compared with the spine hierarchical TiO2 microspheres (5.15%). There is the potential application for microsphere assembly of mesoporous TiO2 nanosheets in quasi-solid-state dye-sensitized solar cells with excellent stability.

  1. Preparation of ultra-thin and high-quality WO3 compact layers and comparision of WO3 and TiO2 compact layer thickness in planar perovskite solar cells

    NASA Astrophysics Data System (ADS)

    Zhang, Jincheng; Shi, Chengwu; Chen, Junjun; Wang, Yanqing; Li, Mingqian

    2016-06-01

    In this paper, the ultra-thin and high-quality WO3 compact layers were successfully prepared by spin-coating-pyrolysis method using the tungsten isopropoxide solution in isopropanol. The influence of WO3 and TiO2 compact layer thickness on the photovoltaic performance of planar perovskite solar cells was systematically compared, and the interface charge transfer and recombination in planar perovskite solar cells with TiO2 compact layer was analyzed by electrochemical impedance spectroscopy. The results revealed that the optimum thickness of WO3 and TiO2 compact layer was 15 nm and 60 nm. The planar perovskite solar cell with 15 nm WO3 compact layer gave a 9.69% average and 10.14% maximum photoelectric conversion efficiency, whereas the planar perovskite solar cell with 60 nm TiO2 compact layer achieved a 11.79% average and 12.64% maximum photoelectric conversion efficiency.

  2. Effect of a Coadsorbent on the Performance of Dye-Sensitized TiO2 Solar Cells: Shielding versus Band-Edge Movement

    SciTech Connect

    Frank, A. J.; Neale, N. R.; Kopidakis, N.; van de Lagemaat, J.; Gratzel, M.

    2005-11-01

    The objective of this research is to determine the operational characteristics key to efficient, low-cost, stable solar cells based on dye-sensitized mesoporous films (in collaboration with DOE's Office of Science Program). Toward this end, we have investigated the mechanism by which the adsorbent chenodeoxycholate, cografted with a sensitizer onto TiO2 nanocrystals, improves the open-circuit photovoltage (VOC) and short-circuit photocurrent density (JSC). We find that adding chenodeoxycholate not only shifts the TiO2 conduction-band edge to negative potentials but also accelerates the rate of recombination. The net effect of these opposing phenomena is to produce a higher photovoltage. It is also found that chenodeoxycholate reduces the dye loading significantly but has only a modest effect on JSC. Implications of these results to developing more efficient cells are discussed.

  3. Preparation of SnS/CdS Co-sensitized TiO2 Photoelectrodes for Quantum Dots Sensitized Solar Cells

    NASA Astrophysics Data System (ADS)

    Xie, Yu-Long; Song, Ping; Zhao, Su-Qing

    2016-10-01

    TiO2 porous films have been prepared by electrophoresis deposition method, while tin sulfide (SnS) and cadmium sulfide quantum dots (QDs) have been deposited by a simple and inexpensive successive ionic layer adsorption and reaction method. The CdS and SnS QDs modifications expanded the photoresponse range of TiO2 nanoparticles from the ultraviolet region to visible range. Such prepared SnS/CdS/TiO2 films were used as photo-anodes to assemble QDs sensitized solar cells with I-/I3 - liquid electrolyte and Pt-coated fluorine-doped tin oxide glass counter electrode. The best resulting cells had an open circuit voltage of 520 mV, a short circuit current density of 2.972 mA cm-2, a fill factor of 0.61, and with a conversion efficiency of 0.936%.

  4. All solid-state solar cells based on CH3NH3PbI3-sensitized TiO2 nanotube arrays

    NASA Astrophysics Data System (ADS)

    Yang, Xiuchun; Liu, Wei; Ren, Peng

    2016-09-01

    TiO2 nanotube arrays (TiO2 NTAs) were firstly used as photoanode in methylammonium lead iodide (CH3NH3PbI3) perovskite/TiO2 NTAs heterojunction solar cell, where CH3NH3PbI3 functions as both light absorber and hole conductor. The composition, structure and photoelectrochemical properties of the as-prepared samples were characterized by x-ray diffractometer (XRD), field-emission scanning electron microscope (FE-SEM), ultraviolet-visible (UV-vis) spectrophotometer and electrochemical workstation. The results indicate that the as-prepared CH3NH3PbI3 belongs to the cubic crystal system, and TiO2 NTAs sensitized by 0.3 M CH3NH3I and PbI2 exhibit the best photoelectrochemical properties with an open-circuit voltage of 0.422 V and a short-circuit current density of 173.4 μA cm-2. The EIS result shows that the extremely large resistance at CH3NH3PbI3/FTO interface contributes to the low current density of the perovskite solar cell.

  5. Front-side illuminated CdS/CdSe quantum dots co-sensitized solar cells based on TiO2 nanotube arrays

    NASA Astrophysics Data System (ADS)

    Guan, Xiao-Fang; Huang, Shu-Qing; Zhang, Quan-Xin; Shen, Xi; Sun, Hui-Cheng; Li, Dong-Mei; Luo, Yan-Hong; Yu, Ri-Cheng; Meng, Qing-Bo

    2011-11-01

    We fabricated a front-side illuminated CdS/CdSe quantum dots co-sensitized solar cell based on TiO2 nanotube arrays. The freestanding TiO2 nanotube arrays were first detached from anodic oxidized Ti foils and then transferred to the fluorine-doped tin oxide to form photoanodes. An opaque Cu2S with high electrochemical activity was used as the counter electrode. A photovoltaic conversion efficiency as high as 3.01% under one sun illumination has been achieved after optimizing the deposition time of CdSe quantum dots and the length of the TiO2 nanotube arrays. It is observed that the power conversion efficiency of quantum dots sensitized solar cells from the front-side illumination mode (3.01%) is much higher than that of the back-side illumination mode (1.32%) owing to the poor catalytic activity of Pt to polysulfide electrolytes and light absorption by the electrolytes for the latter.

  6. Structural and optical characterization of electrodeposited CdSe in mesoporous anatase TiO2 for regenerative quantum-dot-sensitized solar cells.

    PubMed

    Sauvage, Frédéric; Davoisne, Carine; Philippe, Laetitia; Elias, Jamil

    2012-10-01

    We investigated CdSe-sensitized TiO(2) solar cells by means of electrodeposition under galvanostatic control. The electrodeposition of CdSe within the mesoporous film of TiO(2) gives rise to a uniform, thickness controlled, conformal layer of nanostructured CdSe particles intimately wrapping the anatase TiO(2) nanoparticles. This technique has the advantage of providing not only a fast method for sensitization ( < 5 min) but also being easily scalable to the sensitization of large-area panels. XRD together with SAED analysis highlight that the deposit of CdSe is exclusively constituted of the hexagonal polymorph. In addition, hierarchical growth has also been shown, starting from the formation of a TiO(2)-CdSe core-shell structure followed by the growth of an assembly of CdSe nanoparticles resembling cauliflowers. This assembly exhibits at its core a mosaic texture with crystallites of about 3 nm in size, in contrast to a shell composed of well-crystallized single crystals between 5 and 10 nm in size. Preliminary results on the photovoltaic performance of such a nanostructured composite of TiO(2) and CdSe show 0.8% power conversion efficiency under A.M.1.5 G conditions-100 mW cm(-2) in association with a new regenerative redox couple based on cobalt(+III/+II) polypyridil complex (V(oc ) = 485 mV, J(sc ) = 4.26 mA cm (-2), ff=0.37).

  7. Structural and optical characterization of electrodeposited CdSe in mesoporous anatase TiO2 for regenerative quantum-dot-sensitized solar cells.

    PubMed

    Sauvage, Frédéric; Davoisne, Carine; Philippe, Laetitia; Elias, Jamil

    2012-10-01

    We investigated CdSe-sensitized TiO(2) solar cells by means of electrodeposition under galvanostatic control. The electrodeposition of CdSe within the mesoporous film of TiO(2) gives rise to a uniform, thickness controlled, conformal layer of nanostructured CdSe particles intimately wrapping the anatase TiO(2) nanoparticles. This technique has the advantage of providing not only a fast method for sensitization ( < 5 min) but also being easily scalable to the sensitization of large-area panels. XRD together with SAED analysis highlight that the deposit of CdSe is exclusively constituted of the hexagonal polymorph. In addition, hierarchical growth has also been shown, starting from the formation of a TiO(2)-CdSe core-shell structure followed by the growth of an assembly of CdSe nanoparticles resembling cauliflowers. This assembly exhibits at its core a mosaic texture with crystallites of about 3 nm in size, in contrast to a shell composed of well-crystallized single crystals between 5 and 10 nm in size. Preliminary results on the photovoltaic performance of such a nanostructured composite of TiO(2) and CdSe show 0.8% power conversion efficiency under A.M.1.5 G conditions-100 mW cm(-2) in association with a new regenerative redox couple based on cobalt(+III/+II) polypyridil complex (V(oc ) = 485 mV, J(sc ) = 4.26 mA cm (-2), ff=0.37). PMID:22972037

  8. Improving efficiency by hybrid TiO(2) nanorods with 1,10-phenanthroline as a cathode buffer layer for inverted organic solar cells.

    PubMed

    Sun, Chunming; Wu, Yulei; Zhang, Wenjun; Jiang, Nianquan; Jiu, Tonggang; Fang, Junfeng

    2014-01-22

    We reported a significant improvement in the efficiency of organic solar cells by introducing hybrid TiO2:1,10-phenanthroline as a cathode buffer layer. The devices based on polymer thieno[3,4-b]thiophene/benzodithiophene:[6,6]-phenyl C71-butyric acid methyl ester (PTB7:PC71BM) with hybrid buffer layer exhibited an average power conversion efficiency (PCE) as high as 8.02%, accounting for 20.8% enhancement compared with the TiO2 based devices. The cathode modification function of this hybrid material could also be extended to the poly(3-hexylthiophene):[6,6]-phenyl-C61-butyric acid methyl ester (P3HT:PC61BM) system. We anticipate that this study will stimulate further research on hybrid materials to achieve more efficient charge collection and device performance.

  9. Study of copper sulfide counter electrode on the performances of CdS/CdSe/ZnS-sensitized hierarchical TiO2 spheres quantum dots solar cells

    NASA Astrophysics Data System (ADS)

    Buatong, Nattha; Tang, I.-Ming; Pon-On, Weeraphat

    2015-07-01

    The effects of using copper sulfide (CuS) counter electrodes on the performances of solar cells made with CdS/CdSe/ZnS quantum dots co-sensitized onto hierarchical TiO2 spheres (HTS) used as photoelectrode is reported. The HTS in the QDSSCs is composed of an assembly of numerous TiO2 spheres made by the solvolthermal method. The photoelectrical performance of HTS/CdS/CdSe/ZnS coupled to CuS counter electrode was compared to those coupled to Pt CE. The HTS/CdS/CdSe/ZnS coupled to the CuS CE showed the highest power conversion efficiency η (of 1.310 %.) which is significantly higher than those using a standard Pt CE (η = 0.374%) (3.50 fold). This higher efficiency is the results of the higher electrocatalytic activities when the copper sulfide CEs is used.

  10. A cylindrical core-shell-like TiO2 nanotube array anode for flexible fiber-type dye-sensitized solar cells

    PubMed Central

    2011-01-01

    A versatile anodization method was reported to anodize Ti wires into cylindrical core-shell-like and thermally crystallized TiO2 nanotube (TNT) arrays that can be directly used as the photoanodes for semi- and all-solid fiber-type dye-sensitized solar cells (F-DSSC). Both F-DSSCs showed higher power conversion efficiencies than or competitive to those of previously reported counterparts fabricated by depositing TiO2 particles onto flexible substrates. The substantial enhancement is presumably attributed to the reduction of grain boundaries and defects in the prepared TNT anodes, which may suppress the recombination of the generated electrons and holes, and accordingly lead to more efficient carrier-transfer channels. PMID:21711629

  11. Surface thulium-doped TiO2 nanoparticles used as photoelectrodes in dye-sensitized solar cells: improving the open-circuit voltage

    NASA Astrophysics Data System (ADS)

    Aguilar, Teresa; Navas, Javier; Alcántara, Rodrigo; Fernández-Lorenzo, Concha; Blanco, Ginesa; Sánchez-Coronilla, Antonio; Martín-Calleja, Joaquín

    2015-11-01

    This study presents the incorporation of thulium oxide onto the surface of TiO2 nanoparticles, which were used as the photoelectrode in dye-sensitized solar cells. The Tm-TiO2-based semiconductors were widely characterized using techniques such as atomic emission spectroscopy, X-ray diffraction, Raman spectroscopy, UV-Vis spectroscopy, and X-ray photoelectron spectroscopy. The presence of a Tm oxide on the surface was confirmed, and neither the crystalline phases present nor the band gap of TiO2 were affected. In turn, the presence of Tm3+ resulted in new electronic transitions, which led to luminescence processes in the Tm-TiO2 semiconductors. Furthermore, the use of these semiconductors as photoelectrodes in DSSCs led to an increase in open-circuit voltage of up to 6 %. This increase can be reasonably explained by the negative shift of the flat-band potential of the photoelectrodes.

  12. Photovoltaic performance of TiO2 electrode adsorbed with gardenia yellow purified by nonionic polymeric sorbent in dye-sensitized solar cells.

    PubMed

    Kwon, Oh Oun; Kim, Eui Jin; Lee, Jae Hyeok; Kim, Tae Young; Park, Kyung Hee; Kim, Sang Yook; Suh, Hwa Jin; Lee, Hyo Jung; Lee, Jae Wook

    2015-02-01

    To improve the photovoltaic conversion efficiency in dye-sensitized solar cells (DSSCs), TiO2 electrode adsorbed with gardenia yellow purified by nonionic polymeric sorbent was successfully formulated on nanoporous TiO2 surface. Adsorption and desorption properties of crude gardenia yellow solution on a macroporous resin, XAD-1600, were investigated to purify gardenia yellow because of its strong adsorption and desorption abilities as well as high selectivity. To this end, adsorption equilibrium and kinetic data were measured and fitted using adsorption isotherms and kinetic models. Adsorption and desorption breakthrough curves in a column packed with XAD-1600 resin was obtained to optimize the separation process of gardenia yellow. The photovoltaic performance of the photo-electrode adsorbed with the crude and purified gardenia yellow in DSSCs was compared from current-voltage measurements. The results showed that the photovoltaic conversion efficiency was highly dependent on how to separate and purify gardenia yellow as a photosensitizer.

  13. Hierarchical growth of TiO2 nanosheets on anodic ZnO nanowires for high efficiency dye-sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Miles, David O.; Lee, Chang Soo; Cameron, Petra J.; Mattia, Davide; Kim, Jong Hak

    2016-09-01

    We present a novel route to hierarchical core-shell structures consisting of an anodic ZnO nanowire core surrounded by a shell of TiO2 nanosheets (ZNW@TNS). This material combines the beneficial properties of enhanced electron transport, provided by the nanowire core, with the high surface area and chemical stability of the TiO2 shell. Quasi-solid-state dye-sensitized solar cells (qssDSSCs) are prepared using different quantities of either the bare ZnO nanowires or the hierarchical nanowire structures and the effect on cell performance is examined. It is found that whilst the addition of the bare ZnO nanowires results in a decrease in cell performance, significant improvements can be achieved with the addition of small quantities of the hierarchical structures. Power conversion efficiencies of up to 7.5% are achieved under 1 Sun, AM 1.5 simulated sunlight, with a ∼30% increase compared to non-hierarchical mesoporous TiO2 films. A solid-state DSSC (ssDSSC) with a single component solid polymer also exhibits excellent efficiency of 7.2%. The improvement in cell performance is related to the improved light scattering, surface area and electron transport properties via the use of reflectance spectroscopy, BET surface area measurements and electrochemical impedance spectroscopy.

  14. Extremely stable all solution processed organic tandem solar cells with TiO2/GO recombination layer under continuous light illumination

    NASA Astrophysics Data System (ADS)

    Yusoff, Abd. Rashid Bin Mohd; Jose da Silva, Wilson; Kim, Hyeong Pil; Jang, Jin

    2013-10-01

    One approach to harvest a wide solar spectral solar energy is to stack two solar cells with different absorption characteristics in a tandem cell architecture. Herein, solution processed tandem solar cells, with highly transparent titanium oxide (TiO2) and graphene oxide (GO) as an efficient recombination layer, were designed, fabricated and characterized. We have adopted poly[(4,4'-bis(3-ethylhexyl)dithieno[3,2-b:''3'-d]silole)-2,6-diyl-alt-(2,5-(3-(2-ethylhexyl)thiophen-2-yl)thiazolo[5,4-d]thiazole]:indene-C60 bisadduct (PSEHTT:ICBA) and poly[(4,4'-bis(2-ethylhexyl)dithieno[3,2-b:2',3'-d]silole)-2,6-diyl-alt-(2,1,3-benzothiadiazole)-4,7-diyl]:[6,6]-phenyl-C70 butyric acid methyl ester (PSBTBT:PC70BM) as the active layers for the front and rear cells, respectively. The TiO2/GO serves as an electron and hole collecting and recombination layer. The tandem solar cells showed a high open circuit voltage (VOC) 1.62 V, a moderate short circuit current density (JSC) 8.23 mA cm-2, fill factor (FF) 62.98%, leading to the power conversion efficiency of 8.40%. The obtained VOC value of tandem solar cells is ideal for the summation of VOCs attained from front and rear cells and it is evident that our tandem solar cells are well connected in series. Moreover, this tandem cell exhibits a 20% drop in conversion efficiency under continuous AM illumination for 2880 h.One approach to harvest a wide solar spectral solar energy is to stack two solar cells with different absorption characteristics in a tandem cell architecture. Herein, solution processed tandem solar cells, with highly transparent titanium oxide (TiO2) and graphene oxide (GO) as an efficient recombination layer, were designed, fabricated and characterized. We have adopted poly[(4,4'-bis(3-ethylhexyl)dithieno[3,2-b:''3'-d]silole)-2,6-diyl-alt-(2,5-(3-(2-ethylhexyl)thiophen-2-yl)thiazolo[5,4-d]thiazole]:indene-C60 bisadduct (PSEHTT:ICBA) and poly[(4,4'-bis(2-ethylhexyl)dithieno[3,2-b:2',3'-d]silole)-2,6-diyl-alt-(2

  15. A CdSe thin film: a versatile buffer layer for improving the performance of TiO2 nanorod array:PbS quantum dot solar cells

    NASA Astrophysics Data System (ADS)

    Tan, Furui; Wang, Zhijie; Qu, Shengchun; Cao, Dawei; Liu, Kong; Jiang, Qiwei; Yang, Ying; Pang, Shan; Zhang, Weifeng; Lei, Yong; Wang, Zhanguo

    2016-05-01

    To fully utilize the multiple exciton generation effects in quantum dots and improve the overall efficiency of the corresponding photovoltaic devices, nanostructuralizing the electron conducting layer turns out to be a feasible strategy. Herein, PbS quantum dot solar cells were fabricated on the basis of morphologically optimized TiO2 nanorod arrays. By inserting a thin layer of CdSe quantum dots into the interface of TiO2 and PbS, a dramatic enhancement in the power conversion efficiency from 4.2% to 5.2% was realized and the resulting efficiency is one of the highest values for quantum dot solar cells based on nanostructuralized buffer layers. The constructed double heterojunction with a cascade type-II energy level alignment is beneficial for promoting photogenerated charge separation and reducing charge recombination, thereby responsible for the performance improvement, as revealed by steady-state analyses as well as ultra-fast photoluminescence and photovoltage decays. Thus this paper provides a good buffer layer to the community of quantum dot solar cells.To fully utilize the multiple exciton generation effects in quantum dots and improve the overall efficiency of the corresponding photovoltaic devices, nanostructuralizing the electron conducting layer turns out to be a feasible strategy. Herein, PbS quantum dot solar cells were fabricated on the basis of morphologically optimized TiO2 nanorod arrays. By inserting a thin layer of CdSe quantum dots into the interface of TiO2 and PbS, a dramatic enhancement in the power conversion efficiency from 4.2% to 5.2% was realized and the resulting efficiency is one of the highest values for quantum dot solar cells based on nanostructuralized buffer layers. The constructed double heterojunction with a cascade type-II energy level alignment is beneficial for promoting photogenerated charge separation and reducing charge recombination, thereby responsible for the performance improvement, as revealed by steady

  16. Electrodeposited AgInSe2 onto TiO2 films for semiconductor-sensitized solar cell application: The influence of electrodeposited time

    NASA Astrophysics Data System (ADS)

    Chen, Lung-Chuan; Ho, Yi-Ching; Yang, Ru-Yuan; Chen, Jean-Hong; Huang, Chao-Ming

    2012-06-01

    The influence of electrodeposited time (EDT) on Ag-In-Se species growth onto TiO2 films for possible semiconductor-sensitized solar cells (SSSCs) application was investigated. XRD analysis illustrated that the Ag-In-Se film was predominantly comprised by AgInSe2 species with tetragonal body structure and crystal size of 6.05-7.50 nm when EDT was in the region of 15-60 min at a bias of -1.25 V (verse Hg/Hg2SO4 (MSE)). Scanning electron microscope (SEM) indicated a high porosity of AgInSe2/ITO morphology, permitting electrolytes freely percolated through these films. The prepared AgInSe2 films exhibited n-type semiconductor behavior with two band gap energies at 1.27 and 1.80 eV. Photoelectrochemical measurement reflected that open circuit potential varied little with EDT, however, significant change was associated with short circuit current and fill factor (FF), causing the AgInSe2/TiO2 films with EDT of 45 min exhibited the best solar to electricity conversion efficiency of 0.26%. The AgInSe2/TiO2 films with EDT of 45 min demonstrated the longest electron lifetime according to the open circuit voltage decay analysis.

  17. In situ growth of CuInS2 nanocrystals on nanoporous TiO2 film for constructing inorganic/organic heterojunction solar cells.

    PubMed

    Chen, Zhigang; Tang, Minghua; Song, Linlin; Tang, Guoqiang; Zhang, Bingjie; Zhang, Lisha; Yang, Jianmao; Hu, Junqing

    2013-01-01

    Inorganic/organic heterojunction solar cells (HSCs) have attracted increasing attention as a cost-effective alternative to conventional solar cells. This work presents an HSC by in situ growth of CuInS2(CIS) layer as the photoabsorption material on nanoporous TiO2 film with the use of poly(3-hexylthiophene) (P3HT) as hole-transport material. The in situ growth of CIS nanocrystals has been realized by solvothermally treating nanoporous TiO2 film in ethanol solution containing InCl3 · 4H2O, CuSO4 · 5H2O, and thioacetamide with a constant concentration ratio of 1:1:2. InCl3 concentration plays a significant role in controlling the surface morphology of CIS layer. When InCl3 concentration is 0.1 M, there is a layer of CIS flower-shaped superstructures on TiO2 film, and CIS superstructures are in fact composed of ultrathin nanoplates as 'petals' with plenty of nanopores. In addition, the nanopores of TiO2 film are filled by CIS nanocrystals, as confirmed using scanning electron microscopy image and by energy dispersive spectroscopy line scan analysis. Subsequently, HSC with a structure of FTO/TiO2/CIS/P3HT/PEDOT:PSS/Au has been fabricated, and it yields a power conversion efficiency of 1.4%. Further improvement of the efficiency can be expected by the optimization of the morphology and thickness of CIS layer and the device structure.

  18. In situ growth of CuInS2 nanocrystals on nanoporous TiO2 film for constructing inorganic/organic heterojunction solar cells

    PubMed Central

    2013-01-01

    Inorganic/organic heterojunction solar cells (HSCs) have attracted increasing attention as a cost-effective alternative to conventional solar cells. This work presents an HSC by in situ growth of CuInS2(CIS) layer as the photoabsorption material on nanoporous TiO2 film with the use of poly(3-hexylthiophene) (P3HT) as hole-transport material. The in situ growth of CIS nanocrystals has been realized by solvothermally treating nanoporous TiO2 film in ethanol solution containing InCl3 · 4H2O, CuSO4 · 5H2O, and thioacetamide with a constant concentration ratio of 1:1:2. InCl3 concentration plays a significant role in controlling the surface morphology of CIS layer. When InCl3 concentration is 0.1 M, there is a layer of CIS flower-shaped superstructures on TiO2 film, and CIS superstructures are in fact composed of ultrathin nanoplates as ‘petals’ with plenty of nanopores. In addition, the nanopores of TiO2 film are filled by CIS nanocrystals, as confirmed using scanning electron microscopy image and by energy dispersive spectroscopy line scan analysis. Subsequently, HSC with a structure of FTO/TiO2/CIS/P3HT/PEDOT:PSS/Au has been fabricated, and it yields a power conversion efficiency of 1.4%. Further improvement of the efficiency can be expected by the optimization of the morphology and thickness of CIS layer and the device structure. PMID:23947562

  19. Extremely stable all solution processed organic tandem solar cells with TiO2/GO recombination layer under continuous light illumination.

    PubMed

    Yusoff, Abd Rashid bin Mohd; Jose da Silva, Wilson; Kim, Hyeong Pil; Jang, Jin

    2013-11-21

    One approach to harvest a wide solar spectral solar energy is to stack two solar cells with different absorption characteristics in a tandem cell architecture. Herein, solution processed tandem solar cells, with highly transparent titanium oxide (TiO2) and graphene oxide (GO) as an efficient recombination layer, were designed, fabricated and characterized. We have adopted poly[(4,4'-bis(3-ethylhexyl)dithieno[3,2-b:''3'-d]silole)-2,6-diyl-alt-(2,5-(3-(2-ethylhexyl)thiophen-2-yl)thiazolo[5,4-d]thiazole]:indene-C60 bisadduct (PSEHTT:ICBA) and poly[(4,4'-bis(2-ethylhexyl)dithieno[3,2-b:2',3'-d]silole)-2,6-diyl-alt-(2,1,3-benzothiadiazole)-4,7-diyl]:[6,6]-phenyl-C70 butyric acid methyl ester (PSBTBT:PC70BM) as the active layers for the front and rear cells, respectively. The TiO2/GO serves as an electron and hole collecting and recombination layer. The tandem solar cells showed a high open circuit voltage (VOC) 1.62 V, a moderate short circuit current density (JSC) 8.23 mA cm(-2), fill factor (FF) 62.98%, leading to the power conversion efficiency of 8.40%. The obtained VOC value of tandem solar cells is ideal for the summation of VOCs attained from front and rear cells and it is evident that our tandem solar cells are well connected in series. Moreover, this tandem cell exhibits a 20% drop in conversion efficiency under continuous AM illumination for 2880 h.

  20. Effects of nano anatase-rutile TiO2 volume fraction with natural dye containing anthocyanin on the dye sensitized solar cell performance

    NASA Astrophysics Data System (ADS)

    Agustini, S.; Wahyuono, R. A.; Sawitri, D.; Risanti, D. D.

    2013-09-01

    Since its first development, efforts to improve efficiency of Dye Sensitized Solar Cell (DSSC) are continuously carried out, either through selection of dye materials, the type of semiconductor, counter electrode design or the sandwiched structure. It is widely known that anatase and rutile are phases of TiO2 that often being used for fabrication of DSSC. Rutile is thermodynamically more stable phase having band-gap suitable for absorption of sunlight spectrum. On the other hand, anatase has higher electrical conductivity, capability to adsorp dye as well as higher electron diffusion coefficient than those of rutile. Present research uses mangosteen pericarp and Rhoeo spathacea extracted in ethanol as natural dye containing anthocyanin. These dyes were characterized by using UV-Vis and FTIR, showing that the absorption maxima peaks obtained at 389 nm and 413 nm, for mangosteen and Rhoeo spathacea, respectively. The nano TiO2 was prepared by means of co-precipitation method. The particle size were 9-11 nm and 54.5 nm for anatase and rutile, respectively, according to Scherrer's equation. DSSCs were fabricated in various volume fractions of anatase and rutile TiO2. The fabricated DSSCs were tested under 17 mW/cm2 of solar irradiation. The current-voltage (I-V) characteristic of DSSCs employing 75%: 25% volume fraction of anatase and rutile TiO2 have outstanding result than others. The highest conversion efficiencies of 0.037% and 0.013% are obtained for DSSC employing natural dye extract from mangosteen pericarp and Rhoeo spathacea, respectively.

  1. Excellent Passivation and Low Reflectivity Al2O3/TiO2 Bilayer Coatings for n-Wafer Silicon Solar Cells: Preprint

    SciTech Connect

    Lee, B. G.; Skarp, J.; Malinen, V.; Li, S.; Choi, S.; Branz, H. M.

    2012-06-01

    A bilayer coating of Al2O3 and TiO2 is used to simultaneously achieve excellent passivation and low reflectivity on p-type silicon. This coating is targeted for achieving high efficiency n-wafer Si solar cells, where both passivation and anti-reflection (AR) are needed at the front-side p-type emitter. It could also be valuable for front-side passivation and AR of rear-emitter and interdigitated back contact p-wafer cells. We achieve high minority carrier lifetimes {approx}1 ms, as well as a nearly 2% decrease in absolute reflectivity, as compared to a standard silicon nitride AR coating.

  2. TiO2 hierarchical porous film constructed by ultrastable foams as photoanode for quantum dot-sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Du, Xing; He, Xuan; Zhao, Lei; Chen, Hui; Li, Weixin; Fang, Wei; Zhang, Wanqiu; Wang, Junjie; Chen, Huan

    2016-11-01

    It reported a novel and simple method for the first time to prepare TiO2 hierarchical porous film (THPF) using ultrastable foams as a soft template to construct porous structures. Moreover, dodecanol as one foam component was creatively used as solvent during the synthesis of CdSe quantum dots (QDs) to decrease reaction temperature and simplify precipitation process. The result showed that hierarchical pores in scale of microns introduced by foams were regarded to benefit for high coverage and unimodal distribution of QDs on the surface of THPF to increase the efficiencies of light-harvesting, charge-collection and charge-transfer. The increased efficiencies caused an enhancement in quantum efficiency of the cell and thus remarkably increased the short circuit current density (Jsc). In addition, the decrease of charge recombination resulted in the increase of the open circuit voltage (Voc) as well. The QDSSC based on THPF exhibited about 2-fold higher power conversion efficiency (η = 2.20%, Jsc = 13.82 mA cm-2, Voc = 0.572 V) than that of TiO2 nanoparticles film (TNF) (η = 1.06%, Jsc = 6.70 mA cm-2, Voc = 0.505 V). It provided a basis to use foams both as soft template and carrier to realize simultaneously construction and in-situ sensitization of photoanode in further work.

  3. Tuning band alignment by CdS layers using a SILAR method to enhance TiO2/CdS/CdSe quantum-dot solar-cell performance.

    PubMed

    Zhang, Bingkai; Zheng, Jiaxin; Li, Xiaoning; Fang, Yanyan; Wang, Lin-Wang; Lin, Yuan; Pan, Feng

    2016-04-28

    We report tuning band alignment by optimized CdS layers using a SILAR method to achieve the recorded best performance with about 6% PCE in TiO2/CdS/CdSe QDSSCs. Combining experimental and theoretical studies, we find that a better lattices match between CdS and TiO2 assists the growth of CdSe, and the combined effect of charge transfer and surface dipole moment at the TiO2/CdS/CdSe interface shifts the energy levels of TiO2 upward and increases Voc of the solar cells. More importantly, the band gap of CdS buffer layers is sensitive to the distortion induced by lattice mismatch and numbers of CdS layers. For example, the barrier for charge transfer disappears when there are more than 4 layers of CdS, facilitating the charge injection from CdSe to TiO2.

  4. Effect of the rutile content on the photovoltaic performance of the dye-sensitized solar cells composed of mixed-phase TiO2 photoelectrodes.

    PubMed

    Yun, Tae Kwan; Park, Sung Soo; Kim, Duckhyun; Shim, Jae-Hyun; Bae, Jae Young; Huh, Seong; Won, Yong Sun

    2012-01-28

    The effect of the rutile content on the photovoltaic performance of dye-sensitized solar cells (DSSCs) composed of mixed-phase TiO(2) photoelectrode has been investigated. The mixed-phase TiO(2) particles with varied amounts of rutile, relative to anatase phase, are synthesized by an in situ method where the concentration of sulfate ion is used as a phase-controlling parameter in the formation of TiO(2) using TiCl(4) hydrolysis. The surface area (S(BET)) varies from 33 (pure rutile) to 165 (pure anatase) m(2) g(-1). Generally, both the current density (J(sc)) and photo-conversion efficiency (η) decrease as the rutile content increases. The incorporation of rod-shaped rutile particles causes low uptake of dye due to the reduced surface area, as well as slow electron transport in less efficiently-stacked structure. However, maximum J(sc) (14.63 mA cm(-2)) and η (8.69%) appear when relatively low rutile content (16%) is employed. The reported synergistic effect by the efficient interparticle electron transport from rutile to anatase seems to overbalance the decrease of surface area when small amount of rutile particles is incorporated. PMID:22124477

  5. Periodic density functional theory study on the interaction mode and mechanism of typical additives with TiO2 substrates for dye-sensitized solar cell applications

    NASA Astrophysics Data System (ADS)

    Wang, Xiao-Lin; Wu, Meng; Ding, Jie; Li, Ze-Sheng; Sun, Ke-Ning

    2014-01-01

    Five typical additives N-Butylbenzimidazole (NBB), N-Methylbenzimidazole (NMBI), 3-Methoxypropionitrile (MPN), 4-tert-butylpyridine (TBP) and Guanidinium thiocyanate (GNCS) are selected to investigate the diverse interactions with TiO2 anatase (101), (100) and (001) surfaces in vacuum and acetonitrile conditions, respectively, by means of the analyses of adsorption mode and electronic structure based on a periodic density functional theory method. Five additives are adsorbed more strongly in the order (101) < (100) < (001). The defects that appear in the upmost TiO2 (001) surface induced by additive adsorption affect bonding greatly. GNCS possesses the maximum adsorption energy due to special multidentate and dissociative adsorption modes, while MPN has the minimum adsorption energy, no matter which surface is used. Positive Fermi energy shift (i.e. negative potential shift) is in the order (100) < (001) < (101) for every additive adsorption. The larger shift results in the higher open-circuit photovoltage of dye-sensitized solar cells. Acetonitrile addition reduces the adsorption energy but improves the shift trend of Fermi energy except TBP-TiO2 (100) and (001) systems. There should be a critical point of adsorption density for MPN and TBP adsorption on the TiO2 (100) and (001) surfaces, changing Fermi energy shift from negative to positive value.

  6. Fabrication of 3D interconnected porous TiO2 nanotubes templated by poly(vinyl chloride-g-4-vinyl pyridine) for dye-sensitized solar cells.

    PubMed

    Koh, Joo Hwan; Koh, Jong Kwan; Seo, Jin Ah; Shin, Jong-Shik; Kim, Jong Hak

    2011-09-01

    Porous TiO(2) nanotube arrays with three-dimensional (3D) interconnectivity were prepared using a sol-gel process assisted by poly(vinyl chloride-graft-4-vinyl pyridine), PVC-g-P4VP graft copolymer and a ZnO nanorod template. A 7 µm long ZnO nanorod array was grown from the fluorine-doped tin oxide (FTO) glass via a liquid phase deposition method. The TiO(2) sol-gel solution templated by the PVC-g-P4VP graft copolymer produced a random 3D interconnection between the adjacent ZnO nanorods during spin coating. Upon etching of ZnO, TiO(2) nanotubes consisting of 10-15 nm nanoparticles were generated, as confirmed by wide-angle x-ray scattering (WAXS), energy-filtering transmission electron microscopy (EF-TEM) and field-emission scanning electron microscopy (FE-SEM). The ordered and interconnected nanotube architecture showed an enhanced light scattering effect and increased penetration of polymer electrolytes in dye-sensitized solar cells (DSSC). The energy conversion efficiency reached 1.82% for liquid electrolyte, and 1.46% for low molecular weight (M(w)) and 0.74% for high M(w) polymer electrolytes.

  7. Hydrothermal Synthesis of TiO2 Porous Hollow Nanospheres for Coating on the Photoelectrode of Dye-Sensitized Solar Cells

    NASA Astrophysics Data System (ADS)

    Madhu Mohan, Varishetty; Murakami, Kenji

    2012-02-01

    Various sizes of TiO2 hollow nanosphers were synthesized by a hydrolysis followed by the hydrothermal treatment using different water content and titanium isopropoxide (TTIP) while the remaining components such as methylamine, ethanol and acetonitrile were kept as a constant. We synthesized the various sizes of spheres, 150, 250, 400, 450, and 600 nm in diameter; those are represented as SP150, SP250, SP400, SP450, and SP600. The prepared spheres diameters were confirmed by scanning electron microscopy (SEM). These spheres were coated by using a simple spray technique with the TiO2 colloidal solution as a scattering layer for the TiO2 photoelectrode of dye-sensitized solar cells. Optical absorption measurements did not find a difference in the dye adsorption amount with and without the scattering layer. The scattering effect was observed by incident photon to current conversion efficiency (IPCE) measurements especially in the wavelength region of 550-700 nm. The current-voltage (I-V) measurements show that the scattering layer with 450 nm spheres coated on the photoelectrode gave the improved photovoltaic performances compared to other diameters of the spheres. In the present study, the best energy conversion efficiency of 9.56% was obtained for the photoelectrode with the scattering layer, while the pure photoelectrode without the layer gave 8.4%.

  8. Rational design of anatase TiO2 architecture with hierarchical nanotubes and hollow microspheres for high-performance dye-sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Gu, Jiuwang; Khan, Javid; Chai, Zhisheng; Yuan, Yufei; Yu, Xiang; Liu, Pengyi; Wu, Mingmei; Mai, Wenjie

    2016-01-01

    Large surface area, sufficient light-harvesting and superior electron transport property are the major factors for an ideal photoanode of dye-sensitized solar cells (DSSCs), which requires rational design of the nanoarchitectures and smart integration of state-of-the-art technologies. In this work, a 3D anatase TiO2 architecture consisting of vertically aligned 1D hierarchical TiO2 nanotubes (NTs) with ultra-dense branches (HTNTs, bottom layer) and 0D hollow TiO2 microspheres with rough surface (HTS, top layer) is first successfully constructed on transparent conductive fluorine-doped tin oxide glass through a series of facile processes. When used as photoanodes, the DSSCs achieve a very large short-current density of 19.46 mA cm-2 and a high overall power conversion efficiency of 8.38%. The remarkable photovoltaic performance is predominantly ascribed to the enhanced charge transport capacity of the NTs (function as the electron highway), the large surface area of the branches (act as the electron branch lines), the pronounced light harvesting efficiency of the HTS (serve as the light scattering centers), and the engineered intimate interfaces between all of them (minimize the recombination effect). Our work demonstrates a possibility of fabricating superior photoanodes for high-performance DSSCs by rational design of nanoarchitectures and smart integration of multi-functional components.

  9. Correlation between Energy and Spatial Distribution of Intragap Trap States in the TiO2 Photoanode of Dye-Sensitized Solar Cells.

    PubMed

    Wang, Yi; Wu, Dapeng; Fu, Li-Min; Ai, Xi-Cheng; Xu, Dongsheng; Zhang, Jian-Ping

    2015-07-20

    The energy and spatial distribution of intragap trap states of the TiO2 photoanode of dye-sensitized solar cells and their impact on charge recombination were investigated by means of time-resolved charge extraction (TRCE) and transient photovoltage (TPV). The photoanodes were built from TiO2 nanospheroids with different aspect ratios, and the TRCE results allowed differentiation of two different types of trap states, that is, deep and shallow ones at the surface and in the bulk of the TiO2 particles, respectively. These trap states exhibit distinctly different characteristic energy with only a slight variation in the particle size, as derived from the results of the density of states. Analyses of the size-dependent TPV kinetics revealed that in a moderate photovoltage regime of about 375-625 mV, the dynamics of electron recombination are dominated by shallow trap states in the bulk, which can be well accounted for by the mechanism of multiple-trap-limited charge transport.

  10. Effect of thermal treatment on TiO2 nanorod electrodes prepared by the solvothermal method for dye-sensitized solar cells: Surface reconfiguration and improved electron transport

    NASA Astrophysics Data System (ADS)

    Zhao, Jingyong; Yao, Jianxi; Zhang, Yongzhe; Guli, Mina; Xiao, Li

    2014-06-01

    Solvothermal synthesis is considered a novel method of preparing the photoanode in dye-sensitized solar cells (DSSCs), which can directly synthesize material with good crystallinity at low temperatures without thermal treatment. However, how thermal treatment influences the properties of the materials synthesized by this method is still unclear, especial at the microscopic level. In this study, we applied TiO2 nanorod arrays prepared by the solvothermal method to DSSCs. X-ray Diffraction (XRD) and Raman results indicate that the crystal structure of TiO2 nanorods did not change after thermal treatment. However, the photovoltaic performance improved by 39%. Detailed analysis of high-resolution transmission electron microscopy (HRTEM) results demonstrate that a surface reconfiguration occurred, shifting one thin amorphous TiO2 layer to tiny crystallite spheres. The X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FTIR) measurements further confirm this morphology change, and the surface states also become more suitable for dye absorption, which leads to a significant improvement in efficiency. Moreover, good electrical transport is observed due to the low concentration of surface defects. Therefore, we believe the performance improvement comes from crystalline surface and surface chemical bonding improvements. Our results could be useful in photoelectrical applications of the solvothermal synthesis method.

  11. An integrated power pack of dye-sensitized solar cell and Li battery based on double-sided TiO2 nanotube arrays.

    PubMed

    Guo, Wenxi; Xue, Xinyu; Wang, Sihong; Lin, Changjian; Wang, Zhong Lin

    2012-05-01

    We present a new approach to fabricate an integrated power pack by hybridizing energy harvest and storage processes. This power pack incorporates a series-wound dye-sensitized solar cell (DSSC) and a lithium ion battery (LIB) on the same Ti foil that has double-sided TiO(2) nanotube (NTs) arrays. The solar cell part is made of two different cosensitized tandem solar cells based on TiO(2) nanorod arrays (NRs) and NTs, respectively, which provide an open-circuit voltage of 3.39 V and a short-circuit current density of 1.01 mA/cm(2). The power pack can be charged to about 3 V in about 8 min, and the discharge capacity is about 38.89 μAh under the discharge density of 100 μA. The total energy conversion and storage efficiency for this system is 0.82%. Such an integrated power pack could serve as a power source for mobile electronics.

  12. Modification of ZnS-inserting layer in the TiO2 inverse opal-based photoanode to enhance the efficiency of quantum dot-sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Deng, Fei; Wan, Xiangyu; Mei, Xingan; Fan, Runzhou; Yan, Xuemin; Wan, Li; Shi, Dean; Xiong, Yan

    2016-07-01

    Modification of ZnS-inserting layer in the titanium dioxide (TiO2) inverse opal-based photoanode was investigated, and it is an effective and easy approach to enhance the efficiency of quantum dot-sensitized solar cells (QDSSCs). The introduction of ZnS between TiO2 and quantum dots (QDs) not only enhanced the light harvesting of QDs on its top, but also lessened the charge-transfer resistances at the TiO2/QD/electrolyte interfaces. The TiO2 inverse opal-based QDSSCs increased the energy conversion efficiency by modifying the ZnS-inserting layer in the photoanode, particularly the CdS/CdSe QD co-sensitized solar cells which attained 79% rate of increase in cell efficiency.

  13. SiO(2) /TiO(2) hollow nanoparticles decorated with Ag nanoparticles: enhanced visible light absorption and improved light scattering in dye-sensitized solar cells.

    PubMed

    Hwang, Sun Hye; Shin, Dong Hoon; Yun, Juyoung; Kim, Chanhoi; Choi, Moonjung; Jang, Jyongsik

    2014-04-01

    Hollow SiO2 /TiO2 nanoparticles decorated with Ag nanoparticles (NPs) of controlled size (Ag@HNPs) were fabricated in order to enhance visible-light absorption and improve light scattering in dye-sensitized solar cells (DSSCs). They exhibited localized surface plasmon resonance (LSPR) and the LSPR effects were significantly influenced by the size of the Ag NPs. The absorption peak of the LSPR band dramatically increased with increasing Ag NP size. The LSPR of the large Ag NPs mainly increased the light absorption at short wavelengths, whereas the scattering from the SiO2 /TiO2 HNPs improved the light absorption at long wavelengths. This enabled the working electrode to use the full solar spectrum. Furthermore, the SiO2 layer thickness was adjusted to maximize the LSPR from the Ag NPs and avoid corrosion of the Ag NPs by the electrolyte. Importantly, the power conversion efficiency (PCE) increased from 7.1 % with purely TiO2 -based DSSCs to 8.1 % with HNP-based DSSCs, which is an approximately 12 % enhancement and can be attributed to greater light scattering. Furthermore, the PCEs of Ag@HNP-based DSSCs were 11 % higher (8.1 vs. 9.0 %) than the bare-HNP-based DSSCs, which can be attributed to LSPR. Together, the PCE of Ag@HNP-based DSSCs improved by a total of 27 %, from 7.1 to 9.0 %, due to these two effects. This comparative research will offer guidance in the design of multifunctional nanomaterials and the optimization of solar-cell performance.

  14. Enhanced performance of dye-sensitized solar cells aided by Sr,Cr co-doped TiO2 xerogel films made of uniform spheres.

    PubMed

    Bakhshayesh, A M; Bakhshayesh, N

    2015-12-15

    One-pot preparation of Sr,Cr co-doped TiO2 xerogel film for boosting the short circuit current density of dye-sensitized solar cells (DSCs) is reported. The 2.5-μm-diameter spheres are assembled from 60nm nanoparticles by a modified sol-gel method. X-ray photoelectron spectroscopy (XPS) shows that Sr(2+) and Cr(3+) ions to be well incorporated into the titania crystal lattice without forming specific strontium and chromium compositions. The crystallite size, phase composition, and band structure of the particles depend on the dopants concentration. Isolated energy levels near valence band as a result of the transition ion (i.e., Cr) introduction, in conjunction with the local lattice distortions owing to the alkaline earth ion (i.e., Sr) insertion, improves the photocatalytic activity of the prepared TiO2 spheres, enhancing the short circuit current density of the cells. The DSC co-doped with 0.075 at.% Sr and 2.5 at.% Cr (i.e., S7C25 solar cell) showed the highest power conversion efficiency of 7.89% and short circuit current density of 18.58mA/cm(2) thanks to lower charge transfer resistance (2.35Ωcm(2)), lower electron transit time (1.26ms), and higher electron diffusion coefficient (17.1×10(4)cm(2)S(-1)) compared to the other cells, demonstrated by electrochemical impedance spectroscopy (EIS). The concept of simultaneously introduction of alkaline earth ions and transition ions into TiO2 lattice will open up a new insight into the fabrication of high performance DSCs.

  15. Hierarchical TiO2 microspheres comprised of anatase nanospindles for improved electron transport in dye-sensitized solar cells.

    PubMed

    Wu, Dapeng; Wang, Yi; Dong, Hui; Zhu, Feng; Gao, Shuyan; Jiang, Kai; Fu, Limin; Zhang, Jianping; Xu, Dongsheng

    2013-01-01

    Hierarchical TiO(2) microspheres assembled by nanospindles were prepared via a two-step hydrothermal method. The as-prepared products have uniform diameters of ~450 nm and surface area of ~88 m(2) g(-1). The optical investigation evidenced that the photoanode film has a prominent light scattering effect at a wavelength range of 600-800 nm and possesses enhanced dye loading capacity. In addition, the electron recombination and transport dynamic measurements indicated that these hierarchical products could suppress the recombination and improve the diffusion coefficient of the photoelectrons, which can be attributed to the improvement of the connectivity by bridging the neighbouring microspheres through the embedded nanospindles. As a result, a high power conversion efficiency of 8.5% was demonstrated, indicating a ~30% improvement compared with the cell derived from the well-defined nanocrystalline microspheres (6.5%). PMID:23165289

  16. Improvement of solar energy conversion with Nb-incorporated TiO2 hierarchical microspheres.

    PubMed

    Hoang, Son; Ngo, Thong Q; Berglund, Sean P; Fullon, Raymond R; Ekerdt, John G; Mullins, C Buddie

    2013-07-22

    Niobium-modified TiO2 hierarchical spherical micrometer-size particles, which consist of many nanowires, are synthesized by solvothermal synthesis and studied as photoelectrodes for water photo-oxidation and dye-sensitized solar cell (DSSC) applications. Incorporation of Nb leads to a rutile-to-anatase TiO2 phase transition in the TiO2 hierarchical spheres (HSs), with the anatase percentage increasing from 0% for the pristine TiO2 HSs to 47.6% for the 1.82 at.% Nb-incorporated TiO2 sample. Incorporation of Nb leads to significant improvements in water photo-oxidation with the photocurrents reaching 70.5 μA cm(-2) at 1.23 V versus the reversible hydrogen electrode, compared with 28.3 μA cm(-2) for the pristine TiO2 sample. The photoconversion efficiency of Nb:TiO2 HS-based DSSCs reaches 6.09±0.15% at 0.25 at.% Nb, significantly higher than that for the pristine TiO2 HS cells (3.99±0.02%). In addition, the incident-photon-to-current efficiency spectra for DSSCs show that employing TiO2 and Nb:TiO2 HSs provides better light harvesting, especially of long-wavelength photons, than anatase TiO2 nanoparticle-based DSSCs. PMID:23512241

  17. Study of TiO2 nano-tubes using electrochemical anodization method for applications in dye-sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Ghani, T.; Mujahid, M.; Mehmood, M.; Shahzad, Q.

    2016-08-01

    TiO2 nano-tubes are getting strong attraction in many fields due to their unique properties. They are important in biomedical application, Dye sensitized solar cells, sensor and photocatalys is applications, etc. Our prime interest is to grow these tubes for dye-sensitized solar cells with high conversion efficiency and low production cost. In this research, we have synthesized TiO2 naonotubes by anodizing 25 µm thick titanium foil at 40V using two-step anodization method. The electrolyte used is the ethylene glycol with varying concentration of NH4F and fixed concentration of deionized water. Effect of different concentrations of the electrolyte on tube crystal structure has been studied. It is observed that crystallinity increases with increased concentration of fluoride ions. It is found that two-stepanodization method results in more crystalline and open structures. Scanning electron microscopy is utilized to study the surface morphology and tubes growth, whereas observation of the crystal structure of nano-tubes is made by X-ray diffraction.

  18. One-pot synthesis of Cd1- x In x Te semiconductor as a sensitizer on TiO2 mesoporous for potential solar cell devices

    NASA Astrophysics Data System (ADS)

    Singsa-ngah, Mutika; Tubtimtae, Auttasit

    2015-08-01

    We demonstrated the synthesis of a new ternary semiconductor nanoparticle Cd1- x In x Te, as a sensitizer for solar cell devices via a one-pot mixed precursor solution. The Cd1- x In x Te nanoparticles (NPs) were prepared using the chemical bath deposition process and coated onto a TiO2 photoelectrode. A tetragonal structure of Cd1- x In x Te NPs was constituted on the TiO2 photoelectrode with a diameter range ˜25-30 nm, and the atomic percentages of the chemical elements showed that the structure could be Cd0.1In0.9Te incorporated with the CdIn2Te4 structure. When the dipping cycle increased, the energy gaps became narrower from 1.2 to 0.6 eV due to the increasing amount and the larger size of nanoparticles. The photovoltaic properties of various cycles were investigated, and the best power conversion efficiency ( η) of 0.49 % under full 1 sun illumination (100 mW/cm2, AM 1.5G) was obtained for the seven-cycle-Cd1- x In x Te NPs with a current density ( J sc) of 2.64 mA/cm2, an open-circuit voltage ( V oc) of 638 mV, and a fill factor ( FF) of 0.29. The efficiency of this material can be further improved for higher potential solar cell devices.

  19. The Interface between FTO and the TiO2 Compact Layer Can Be One of the Origins to Hysteresis in Planar Heterojunction Perovskite Solar Cells.

    PubMed

    Jena, Ajay Kumar; Chen, Hsin-Wei; Kogo, Atsushi; Sanehira, Yoshitaka; Ikegami, Masashi; Miyasaka, Tsutomu

    2015-05-13

    Organometal halide perovskite solar cells have shown rapid rise in power conversion efficiency, and therefore, they have gained enormous attention in the past few years. However, hysteretic photovoltaic characteristics, found in these solid-state devices, have been a major problem. Although it is being proposed that the ferroelectric property of perovskite causes hysteresis in the device, we observed hysteresis in a device made of nonferroelectric PbI2 as a light absorber. This result evidently supports the fact that ferroelectric property cannot be the sole reason for hysteresis. The present study investigates the roles of some key interfaces in a planar heterojunction perovskite (CH3NH3PbI(3-x)Cl(x)) solar cell that can potentially cause hysteresis. The results confirm that the interface between fluorine doped tin oxide (FTO) substrate and the TiO2 compact layer has a definite contribution to hysteresis. Although this interface is one of the origins to hysteresis, we think that other interfaces, especially the interface of the TiO2 compact layer with perovskite, can also play major roles. Nevertheless, the results indicate that hysteresis in such devices can be reduced/eliminated by changing the interlayer between FTO and perovskite.

  20. TiO2 quantum dots as superb compact block layers for high-performance CH3NH3PbI3 perovskite solar cells with an efficiency of 16.97%

    NASA Astrophysics Data System (ADS)

    Tu, Yongguang; Wu, Jihuai; Zheng, Min; Huo, Jinghao; Zhou, Pei; Lan, Zhang; Lin, Jianming; Huang, Miaoliang

    2015-12-01

    A compact TiO2 layer is crucial to achieve high-efficiency perovskite solar cells. In this study, we developed a facile, low-cost and efficient method to fabricate a pinhole-free and ultrathin blocking layer based on highly crystallized TiO2 quantum dots (QDs) with an average diameter of 3.6 nm. The surface morphology of the blocking layer and the photoelectric performance of the perovskite solar cells were investigated by spin-coating with three different materials: colloidal TiO2 QDs, titanium precursor solution, and aqueous TiCl4. Among these three treatments, the perovskite solar cell based on the TiO2 QD compact layer offered the highest power conversion efficiency (PCE) of 16.97% with a photocurrent density of 22.48 mA cm-2, a photovoltage of 1.063 V and a fill factor of 0.71. The enhancement of PCE mainly stems from the small series resistance and the large shunt resistance of the TiO2 QD layer.A compact TiO2 layer is crucial to achieve high-efficiency perovskite solar cells. In this study, we developed a facile, low-cost and efficient method to fabricate a pinhole-free and ultrathin blocking layer based on highly crystallized TiO2 quantum dots (QDs) with an average diameter of 3.6 nm. The surface morphology of the blocking layer and the photoelectric performance of the perovskite solar cells were investigated by spin-coating with three different materials: colloidal TiO2 QDs, titanium precursor solution, and aqueous TiCl4. Among these three treatments, the perovskite solar cell based on the TiO2 QD compact layer offered the highest power conversion efficiency (PCE) of 16.97% with a photocurrent density of 22.48 mA cm-2, a photovoltage of 1.063 V and a fill factor of 0.71. The enhancement of PCE mainly stems from the small series resistance and the large shunt resistance of the TiO2 QD layer. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr05563f

  1. Synthesis and characterization of TiO2/SiO2 nano composites for solar cell applications

    NASA Astrophysics Data System (ADS)

    Arun Kumar, D.; Merline Shyla, J.; Xavier, Francis P.

    2012-12-01

    The use of titania-silica in photocatalytic process has been proposed as an alternative to the conventional TiO2 catalysts. Mesoporous materials have been of great interest as catalysts because of their unique textural and structural properties. Mesoporous TiO2, SiO2 nanoparticles and TiO2/SiO2 nanocomposites were successfully synthesized by sol-gel method using titanium (IV) isopropoxide, tetra-ethylorthosilicate as starting materials. The synthesized samples are characterized by X-ray diffraction, UV-Vis spectroscopy, Fourier transform infrared spectroscopy, Brunauett-Emmett-Teller and field-dependent photoconductivity. The UV-Vis spectrum of as-synthesized samples shows similar absorption in the visible range. The crystallite size of the as-synthesized samples was calculated by Scherrer's formula. The BET surface area for TiO2/SiO2 nanocomposite is found to be 303 m2/g and pore size distribution has average pore diameter about 10 nm. It also confirms the absence of macropores and the presence of micro and mesopores. The field-dependent photoconductivity of TiO2/SiO2 nanocomposite shows nearly 300 folds more than that of TiO2 nanoparticle for a field of 800 V/cm.

  2. Microsphere assembly of TiO2 mesoporous nanosheets with highly exposed (101) facets and application in a light-trapping quasi-solid-state dye-sensitized solar cell.

    PubMed

    Tao, Xiyun; Ruan, Peng; Zhang, Xiang; Sun, Hongxia; Zhou, Xingfu

    2015-02-28

    The morphology of nano-titania has a significant effect on the photoelectric properties of dye-sensitized solar cells. In this study, microsphere assembly of a TiO2 mesoporous nanosheet constructed by nanocuboids was conducted via a simple hydrothermal process. The XRD pattern indicated that the hierarchical mesoporous microspheres are anatase phase with decreased (004) peaks. Raman spectrum shows enhanced Eg peaks at 143 and 638 cm(-1) caused by the symmetric stretching vibration of O-Ti-O of the (101) crystalline facet in anatase TiO2. FESEM and TEM images show that well monodispersed TiO2 microspheres with a diameter of 2 μm are assembled by TiO2 mesoporous nanosheets with exposed (101) facets. The oriented attachment of TiO2 nanocuboids along the (101) direction leads to the formation of mesoporous titania nanosheets. The UV-Vis spectrum shows that the mesoporous TiO2 nanosheets have high scattering ability and light absorption by dye. Quasi-solid-state dye-sensitized solar cells that incorporate these microspheres into the top scattering layers exhibit a prominent improvement in the power conversion efficiency of 7.51%, which shows a 45.8% increase in the overall conversion efficiency when compared with the spine hierarchical TiO2 microspheres (5.15%). There is the potential application for microsphere assembly of mesoporous TiO2 nanosheets in quasi-solid-state dye-sensitized solar cells with excellent stability. PMID:25631573

  3. Synergistic effect of TiCl4-ZnO treated TiO2 nanotubes in dye-sensitized solar cell

    NASA Astrophysics Data System (ADS)

    Lee, Jin Soo; Kim, Kyung Hwan; Kim, Chang Seob; Choi, Hyung Wook

    2015-06-01

    Oxide semiconducting TiO2 nanoparticles (TNPs) with TiO2 nanotubes (TNTs) have attracted considerable attention because of a fast electron migration process in the photoelectrode. However, TNT films of dye-sensitized solar cells (DSSCs) displayed low conversion efficiency because of lower dye loading and sunlight absorption than in the case of TNPs films. For high-performance DSSCs, an aqueous solution treatment using titanium tetrachloride (TiCl4) and zinc oxide (ZnO) was used on the TNT film. The TNT array was prepared by an anodization process. Herein, we studied that a double dip-coating TiCl4-ZnO treatment of the TNTs enhanced photocurrent density and fill factor due to an improvement in electron transfer, increase in dye adsorption, and reduction in the recombination charge rate. The results show that the DSSCs with a TiCl4-ZnO treatment show a maximum conversion efficiency of 8.29% and JSC of 21.19 mA/cm2 under a simulated solar light irradiation of 100 mW/cm2 (AM 1.5).

  4. Influence of difference quantity La-doped TiO2 photoanodes on the performance of dye-sensitized solar cells: A strategy for choosing an appropriate doping quantity

    NASA Astrophysics Data System (ADS)

    Zhang, Zige; Li, Guoxiang; Cui, Zijian; Zhang, Kaiyue; Feng, Yaqing; Meng, Shuxian

    2016-05-01

    Facilitated by TiO2 particles adsorbing lanthanide ions in hydrosol, La-doped TiO2 was produced by a hydrothermal method. The structure, optical and photoluminescence properties of down-converting photoelectrode with the La3+ were characterized by X-ray (XRD), Scanning electron microscopy (SEM), Energy dispersive X-ray detector (EDX) and N2 adsorption-desorption isotherms measurement. The photoelectric conversion efficiency of dye-sensitized solar cells (DSSCs) fabricated with 0.05 g-La/TiO2 reached 7.02%, which gave an efficiency improved by 10.36% compared with that of cells fabricated from pure TiO2. The improvement in efficiency was ascribed to more dyes adsorbed on the surface of TiO2.

  5. Enhanced performance of reversely transferred, doubly open-ended TiO2 nanotube arrays for front-illuminated dye-sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Kim, Hyunsoo; Lee, Soo-Yong; Kim, Jae-Hong; Ahn, Kwang-Soon; Kang, Soon-Hyung

    2016-01-01

    Doubly open-ended conventional TiO2 nanotube arrays (Type I) and nanoporous-layer-covered nanotube arrays (Type II) were transferred to transparent fluorine-doped tin oxides (FTOs) for front-illuminated dye-sensitized solar cells (DSSCs). FTO/Type II exhibited a long electron lifetime ( τ e ) and rapid electron transport compared to FTO/Type I because of the reduced surface defect-state-mediated recombination rate. In particular, Type II transferred reversely to the FTO (FTO/Type II-rev) had beneficial geometric effects, leading to a decrease in pore size from the bottom to the top and a nanoporous TiO2 thin bottom layer. These enabled more effective light scattering near the FTO and facilitated lateral electron movement toward the FTO, leading to a shortened electron pathway and a reduced recombination rate. The significantly enhanced electron lifetime and the shortened electron transit time of the FTO/Type II-rev improved the charge collection efficiency significantly. Furthermore, the enhanced light scattering increased the light harvesting efficiency. These beneficial geometric effects of FTO/Type II-rev contributed to the greatly enhanced overall cell efficiency (7.61%) of the DSSC compared to the DSSCs with FTO/Type I (5.27%) and FTO/Type II (6.65%).

  6. The real TiO2/HTM interface of solid-state dye solar cells: role of trapped states from a multiscale modelling perspective.

    PubMed

    Gagliardi, Alessio; Auf der Maur, Matthias; Gentilini, Desiree; di Fonzo, Fabio; Abrusci, Agnese; Snaith, Henry J; Divitini, Giorgio; Ducati, Caterina; Di Carlo, Aldo

    2015-01-21

    In this paper we present a multiscale simulation of charge transport in a solid-state dye-sensitized solar cell, where the real morphology between TiO2 and the hole transport material is included. The geometry of the interface is obtained from an electron tomography measurement and imported in a simulation software. Charge distribution, electric field and current densities are computed using the drift-diffusion model. We use this approach to investigate the electrostatic effect of trap states at the interface between the electron and hole transport materials. The simulations show that when the trapped electrons are not screened by external additives, the dynamics of holes is perturbed. Holes accumulate at the interface, enhancing recombination and reducing cell performance.

  7. High-performance plastic dye-sensitized solar cells based on low-cost commercial P25 TiO2 and organic dye.

    PubMed

    Yin, Xiong; Xue, Zhaosheng; Wang, Long; Cheng, Yueming; Liu, Bin

    2012-03-01

    High-performance plastic dye-sensitized solar cells (DSCs) based on low-cost commercial Degussa P25 TiO(2) and organic indoline dye D149 have been fabricated using electrophoretic deposition (EPD) with compression post-treatment at room temperature. The pressed EPD electrode outperformed the sintered EPD electrode and as-prepared EPD electrode in short-circuit current density and power conversion efficiency. About 150% and 180% enhancement in power conversion efficiency have been achieved in DSC devices with sintering and compression post-treatment as compared to the as-prepared electrode, respectively. Several characterizations including intensity modulated photocurrent spectroscopy, incident photon-to-electron conversion efficiency and electrochemical impedance spectra have been employed to reveal the nature of improvement with post-treatment. Experimental results indicate that the sintering and compression post-treatment are beneficial to improve the electron transport and thus lead to the enhancement of photocurrent and power conversion efficiency. In addition, the compression post-treatment is more efficient than sintering post-treatment in improving interparticle connection in the as-prepared EPD electrode. Under optimized conditions, the conversion efficiency of plastic devices with D149-sensitized P25 TiO(2) photoanode has reached 5.76% under illumination of AM 1.5G (100 mW cm(-2)). This study demonstrates that the EPD combined with compression post-treatment provides a way to fabricate highly efficient plastic photovoltaic devices.

  8. Adsorption of porphyrin and carminic acid on TiO2 nanoparticles: A photo-active nano-hybrid material for hybrid bulk heterojunction solar cells.

    PubMed

    Munir, Shamsa; Shah, Syed Mujtaba; Hussain, Hazrat; Siddiq, Muhammad

    2015-12-01

    A photo-active nano-hybrid material consisting of titania nanoparticles, carminic acid, and sulphonic acid functionalized porphyrin is reported here. In an attempt to extend the absorption spectrum of titania to visible region by co-adsorbing carminic acid and sulphonic acid functionalized porphyrin on its surface. Interesting changes in the UV-visible and fluorescence spectra were noticed. The adsorption of carminic acid resulted in the formation of charge transfer complex with titania nanoparticles. This was confirmed by the electronic absorption and fluorescence emission spectroscopies. Chemisorption of porphyrin on the carminic acid functionalized titania further boosted the charge transfer effect. This was noticed by the increase in intensity and width of the charge transfer absorption and emission bands. Energy level diagram showed that the interaction among the constituents of the nano-hybrid assembly permitted the flow of electron in a cascade manner from carminic acid to TiO2.This also allowed direct flow of electrons either from carminic acid or porphyrin toward titania. The material was used as an active blend in hybrid bulk heterojunction solar cells. Co-functionalized TiO2-based devices were found 3.5 times more efficient than the reference device but morphology of the device proved a major setback. PMID:26555643

  9. High open voltage and superior light-harvesting dye-sensitized solar cells fabricated by flower-like hierarchical TiO2 composed with highly crystalline nanosheets

    NASA Astrophysics Data System (ADS)

    Que, Ya-Ping; Weng, Jian; Hu, Lin-Hua; Wu, Ji-Huai; Dai, Song-Yuan

    2016-03-01

    The morphology, microstructure and crystallography of titanium dioxide (TiO2) have great effect on the photoelectric performance of dye-sensitized solar cells (DSSCs). Herein, flower-like 3D TiO2 microstructures based on well-defined high-crystalline nanosheets are synthesized through a facile hydrothermal method. Especially, morphological evolution process and mechanism of this hierarchical structure are investigated. Due to the highly crystalline nature and smaller surface area of these nanosheets, the corresponding device shows an extremely high open-current voltage up to 0.84 V, which results from the less electron recombination. When applied as a scattering layer on top of the nanoparticle layer, the power conversion efficiency (PCE) can be significantly improved and give birth to a PCE value of 9.6%, which is 24.6% higher than that of an analogous device using nanoparticles (NP) (7.7%). As reflected by diffusion reflection spectra, intensity of the modulated photocurrent/photovoltage spectroscopy (IMPS/IMVS) and electrochemical impedance spectra (EIS), this hierarchical structure can not only enhance light harvesting, but also reduce electron recombination, facilitate electron transport and improve electron collection efficiency.

  10. Morphology-controlled cactus-like branched anatase TiO2 arrays with high light-harvesting efficiency for dye-sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Wu, Wu-Qiang; Rao, Hua-Shang; Feng, Hao-Lin; Guo, Xin-Dong; Su, Cheng-Yong; Kuang, Dai-Bin

    2014-08-01

    The present work establishes a facile process for one-step hydrothermal growth of vertically aligned anatase cactus-like branched TiO2 (CBT) arrays on a transparent conducting oxide (TCO) substrate. Various CBT morphologies are obtained by adjusting the potassium titanium oxide oxalate (PTO) reactant concentration (from 0.05 M to 0.15 M) and this yields a morphologically-controllable branched TiO2 arrays geometry. The CBT arrays consist of a vertically oriented nanowire (NW) or nanosheet (NS) stem and a host of short nanorod (NR) branches. The hierarchical CBT arrays demonstrate their excellent candidatures as photoanodes, which are capable of exhibiting high light-harvesting efficiency in dye-sensitized solar cells (DSSCs). Consequently, DSSCs based on 7 μm long optimized CBT arrays (0.05 M PTO), which are assembled with high density and high aspect-ratio NR branches, exhibit an impressive power conversion efficiency of 6.43% under AM 1.5G one sun illumination. The high performance can be attributed to the prominent light-harvesting efficiency, resulting from larger surface area and superior light-scattering capability.

  11. Worm-like mesoporous TiO2 thin films templated using comb copolymer for dye-sensitized solar cells with polymer electrolyte

    NASA Astrophysics Data System (ADS)

    Lee, Jae Hun; Park, Cheol Hun; Jung, Jung Pyo; Kim, Jong Hak

    2015-12-01

    A comb copolymer consisting of hydrophobic poly(2-[3-(2H-benzotriazol-2-yl)-4-hydroxyphenyl] ethyl methacrylate) (PBEM) and hydrophilic poly(oxyethylene methacrylate) (POEM) is synthesized via one-pot free radical polymerization. The PBEM-POEM comb copolymer is used as an agent to direct the structure toward one consisting of worm-like mesoporous TiO2 (WM-TiO2) films. The selective, preferential interaction between the titania precursor and the hydrophilic POEM chains is responsible for the formation of a well-organized worm-like mesostructure. The morphology of the WM-TiO2 films is characterized by scanning electron microscopy (SEM) and atomic force microscopy (AFM). In particular, the effects of film thickness on the optical and electrochemical properties are systematically investigated. The introduction of the WM-TiO2 layer between the nanocrystalline TiO2 (NC-TiO2) layer and fluorine-doped tin oxide (FTO) glass results in increased transmittance of visible light due to an antireflective property, decreased interfacial resistance and suppressed charge recombination at the interfaces of NC-TiO2/FTO glass. As a result, the photovoltaic conversion efficiency of the dye-sensitized solar cell (DSSC) with a polymer electrolyte is improved from 5.3% to 6.6% at an optimum film thickness (310 nm). The obtained efficiency represents a higher efficiency for the N719-based DSSC with a solvent-free, polymer electrolyte.

  12. Effect of the microstructural characteristics of a Ga-doped TiO2 hole block layer on an inverted structure organic solar cell

    NASA Astrophysics Data System (ADS)

    Lee, Eun Ju; Ryu, Sang Ouk

    2016-09-01

    Inverted-structure organic solar cells (OSCs) were fabricated using atomic-layer-deposition (ALD) processed Ga-doped TiO2 as hole blocking layer (HBL). Measured photovoltaic efficiencies were greatly related to the crystallinity of the TiO2 films. However, the efficiencies of the OSCs and the crystallinity of the HBL did not show a linear relationship. The HBL was fully crystallized at a deposition temperature of 200 °C or above, and the power conversion efficiency was measured to be 2.7% with for the HBL processed at 200 °C, but the efficiency decreased to 2.4% for the HBL processed at 250 °C. On the other hand, the surface roughness of the crystallized films was found be increased to two fold in the studied temperature range. Once the HBL had been fully crystallized, the major factor that determined the overall performance of OSCs was the surface roughness of the HBL.

  13. Adsorption of porphyrin and carminic acid on TiO2 nanoparticles: A photo-active nano-hybrid material for hybrid bulk heterojunction solar cells.

    PubMed

    Munir, Shamsa; Shah, Syed Mujtaba; Hussain, Hazrat; Siddiq, Muhammad

    2015-12-01

    A photo-active nano-hybrid material consisting of titania nanoparticles, carminic acid, and sulphonic acid functionalized porphyrin is reported here. In an attempt to extend the absorption spectrum of titania to visible region by co-adsorbing carminic acid and sulphonic acid functionalized porphyrin on its surface. Interesting changes in the UV-visible and fluorescence spectra were noticed. The adsorption of carminic acid resulted in the formation of charge transfer complex with titania nanoparticles. This was confirmed by the electronic absorption and fluorescence emission spectroscopies. Chemisorption of porphyrin on the carminic acid functionalized titania further boosted the charge transfer effect. This was noticed by the increase in intensity and width of the charge transfer absorption and emission bands. Energy level diagram showed that the interaction among the constituents of the nano-hybrid assembly permitted the flow of electron in a cascade manner from carminic acid to TiO2.This also allowed direct flow of electrons either from carminic acid or porphyrin toward titania. The material was used as an active blend in hybrid bulk heterojunction solar cells. Co-functionalized TiO2-based devices were found 3.5 times more efficient than the reference device but morphology of the device proved a major setback.

  14. Correlations of Optical Absorption, Charge Trapping, and Surface Roughness of TiO2 Photoanode Layer Loaded with Neat Ag-NPs for Efficient Perovskite Solar Cells.

    PubMed

    Yang, Dongwook; Jang, Jae Gyu; Lim, Joohyun; Lee, Jin-Kyu; Kim, Sung Hyun; Hong, Jong-In

    2016-08-24

    We systematically investigated the effect of silver nanoparticles (Ag-NPs) on the power conversion efficiency (PCE) of perovskite solar cells (PSCs). Neat, spherical Ag-NPs at loading levels of 0.0, 0.5, 1.0, and 2.0 wt % were embedded into the titanium dioxide (TiO2) photoanode layer. The plasmonic effect of the Ag-NPs strongly enhanced the incident light absorption over a wide range of the visible wavelength region in addition to the inherent absorbance of the perovskite sensitizer. The low conduction energy level of the Ag-NPs compared to that of TiO2 provides trap sites for free charge carriers. Thus, the correlation between the enhancement of the optical absorption and the number of charge traps provided by the Ag-NPs is critical to determine the device performance, especially current density (Jsc) and PCE. This is confirmed by the quantitative comparison of the incident light absorption and the time-resolved photoluminescence decay according to the loading levels of the Ag-NPs in the TiO2 layer. The absorption enhancement from 380 to 750 nm in the UV-visible spectrum is proportional to the increase in the loading levels of the Ag-NPs. However, the Jsc increases with the device with 0.5 wt % Ag-NPs and gradually decreases with increases in the loading level above 0.5 wt % because of the different contributions to the absorbance and the charge trapping by different Ag-NP loading levels. In addition, the suppression of the surface roughness with dense packing by the Ag-NPs helps to improve the Jsc and the following PCE. Consequently, the PCE of the PSC with 0.5 wt % Ag-NPs is increased to 11.96%. These results are attributed to the balance between increased absorbance by the localized surface plasmon resonance and the decreased charge trapping as well as the decreased surface roughness of the TiO2 layer with the Ag-NPs. PMID:27471777

  15. TiO2 quantum dots as superb compact block layers for high-performance CH3NH3PbI3 perovskite solar cells with an efficiency of 16.97.

    PubMed

    Tu, Yongguang; Wu, Jihuai; Zheng, Min; Huo, Jinghao; Zhou, Pei; Lan, Zhang; Lin, Jianming; Huang, Miaoliang

    2015-12-28

    A compact TiO(2) layer is crucial to achieve high-efficiency perovskite solar cells. In this study, we developed a facile, low-cost and efficient method to fabricate a pinhole-free and ultrathin blocking layer based on highly crystallized TiO(2) quantum dots (QDs) with an average diameter of 3.6 nm. The surface morphology of the blocking layer and the photoelectric performance of the perovskite solar cells were investigated by spin-coating with three different materials: colloidal TiO(2) QDs, titanium precursor solution, and aqueous TiCl(4). Among these three treatments, the perovskite solar cell based on the TiO(2) QD compact layer offered the highest power conversion efficiency (PCE) of 16.97% with a photocurrent density of 22.48 mA cm(-2), a photovoltage of 1.063 V and a fill factor of 0.71. The enhancement of PCE mainly stems from the small series resistance and the large shunt resistance of the TiO(2) QD layer.

  16. TiO2 quantum dots as superb compact block layers for high-performance CH3NH3PbI3 perovskite solar cells with an efficiency of 16.97.

    PubMed

    Tu, Yongguang; Wu, Jihuai; Zheng, Min; Huo, Jinghao; Zhou, Pei; Lan, Zhang; Lin, Jianming; Huang, Miaoliang

    2015-12-28

    A compact TiO(2) layer is crucial to achieve high-efficiency perovskite solar cells. In this study, we developed a facile, low-cost and efficient method to fabricate a pinhole-free and ultrathin blocking layer based on highly crystallized TiO(2) quantum dots (QDs) with an average diameter of 3.6 nm. The surface morphology of the blocking layer and the photoelectric performance of the perovskite solar cells were investigated by spin-coating with three different materials: colloidal TiO(2) QDs, titanium precursor solution, and aqueous TiCl(4). Among these three treatments, the perovskite solar cell based on the TiO(2) QD compact layer offered the highest power conversion efficiency (PCE) of 16.97% with a photocurrent density of 22.48 mA cm(-2), a photovoltage of 1.063 V and a fill factor of 0.71. The enhancement of PCE mainly stems from the small series resistance and the large shunt resistance of the TiO(2) QD layer. PMID:26585357

  17. The Study of Femtosecond Laser Irradiation on GaAs Solar Cells With TiO2/SiO2 Anti-Reflection Films

    NASA Astrophysics Data System (ADS)

    Hua, Yinqun; Shi, Zhiguo; Wu, Wenhui; Chen, Ruifang; Rong, Zhen; Ye, Yunxia; Liu, Haixia

    Femtosecond laser ablation on GaAs solar cells for space power has been investigated. In particular, we studied the effects of laser energy and laser number on the ablation of solar cells. Furthermore, the morphologies and microstructure of ablation were characterized by the non-contact optical profilometer and scanning electron microscope (SEM). The photovoltaic properties were tested by the volt ampere characteristic test system. The abaltion threshold of the TiO2/SiO2 anti-reflection film of GaAs solar cells was obtained from the linear fit of the dependence of the square diameter of the ablated area with the natural logarithm of the femtosecond laser pulse energy, the resulting threshold of the laser fluence is about 0.31J/cm2, and the corresponding energy is 5.4uJ. The ablation depth showed nonlinear dependence of energy. With the fixed energy 6uJ and the increasing laser number, the damage degree increases obviously. Furthermore, the electric properties also suffer a certain degradation. Among all the evaluated electric properties, the photoelectric conversion efficiency (η) degraded remarkably.

  18. Moth-Eye TiO2 Layer for Improving Light Harvesting Efficiency in Perovskite Solar Cells.

    PubMed

    Kang, Seong Min; Jang, Segeun; Lee, Jong-Kwon; Yoon, Jungjin; Yoo, Dong-Eun; Lee, Jin-Wook; Choi, Mansoo; Park, Nam-Gyu

    2016-05-01

    A moth-eye nanostructured mp-TiO2 film using conventional lithography, nano-imprinting and polydimethyl-siloxane (PDMS) stamping methods is demonstrated for the first time. Power conversion efficiency of the moth-eye patterned perovskite solar cell is improved by ≈11%, which mainly results from increasing light harvesting efficiency by structural optical property.

  19. Study on the blocking effect of a quantum-dot TiO2 compact layer in dye-sensitized solar cells with ionic liquid electrolyte under low-intensity illumination

    NASA Astrophysics Data System (ADS)

    Zhai, Peng; Lee, Hyeonseok; Huang, Yu-Ting; Wei, Tzu-Chien; Feng, Shien-Ping

    2016-10-01

    In this study, ultrasmall and ultrafine TiO2 quantum dots (QDs) were prepared and used as a high-performance compact layer (CL) in dye-sensitized solar cells (DSCs). We systematically investigated the performance of TiO2 CL under both low-intensity light and indoor fluorescent light illumination and found that the efficiency of DSCs with the insertion of optimal TiO2 QDs-CL was increased up to 18.3% under indoor T5 fluorescent light illumination (7000 lux). We clarified the controversy over the blocking effect of TiO2 CL for the efficiency increment and confirmed that the TiO2 QDs-CL performed significantly better under low-intensity illumination due to the efficient suppression of electron recombination at the FTO/electrolyte interface. We, for the first time, demonstrate this potential for the application of the DSCs with TiO2 QDs-CL in the low-intensity light and indoor fluorescent light illumination.

  20. Atomic Layer Deposition of TiO2 for a High-Efficiency Hole-Blocking Layer in Hole-Conductor-Free Perovskite Solar Cells Processed in Ambient Air.

    PubMed

    Hu, Hang; Dong, Binghai; Hu, Huating; Chen, Fengxiang; Kong, Mengqin; Zhang, Qiuping; Luo, Tianyue; Zhao, Li; Guo, Zhiguang; Li, Jing; Xu, Zuxun; Wang, Shimin; Eder, Dominik; Wan, Li

    2016-07-20

    In this study we design and construct high-efficiency, low-cost, highly stable, hole-conductor-free, solid-state perovskite solar cells, with TiO2 as the electron transport layer (ETL) and carbon as the hole collection layer, in ambient air. First, uniform, pinhole-free TiO2 films of various thicknesses were deposited on fluorine-doped tin oxide (FTO) electrodes by atomic layer deposition (ALD) technology. Based on these TiO2 films, a series of hole-conductor-free perovskite solar cells (PSCs) with carbon as the counter electrode were fabricated in ambient air, and the effect of thickness of TiO2 compact film on the device performance was investigated in detail. It was found that the performance of PSCs depends on the thickness of the compact layer due to the difference in surface roughness, transmittance, charge transport resistance, electron-hole recombination rate, and the charge lifetime. The best-performance devices based on optimized TiO2 compact film (by 2000 cycles ALD) can achieve power conversion efficiencies (PCEs) of as high as 7.82%. Furthermore, they can maintain over 96% of their initial PCE after 651 h (about 1 month) storage in ambient air, thus exhibiting excellent long-term stability.

  1. Preparation and characterization of nanorod-like TiO2 and ZnO films used for charge-transport buffer layers in P3HT based organic solar cells

    NASA Astrophysics Data System (ADS)

    Thao, Tran Thi; Long, Dang Dinh; Truong, Vo-Van; Dinh, Nguyen Nang

    2016-08-01

    With the aim of findingout the appropriate buffer layers for organic solar cells (OSC), TiO2 and ZnO on ITO/glass were prepared as nanorod-like thin films. The TiO2 films were crystallyzed in the anatase phase and the ZnO films, in the wurtzite structure. The nanorods in both the fims have a similar size of 15 to 20 nm in diameter and 30 to 50 nm in length. The nanorods have an orientation nearly perpendicular to the ITO-substrate surface. From UV-Vis data the bandgap of the TiO2 and ZnO films were determined tobe 3.26 eV and 3.42 eV, respectively. The laminar organic solar cells with added TiO2 and ZnO, namely ITO/TiO2/P3HT:PCBM/LiF/Al (TBD) and ITO/ZnO/P3HT:PCBM/LiF/Al (ZBD)were made for characterization of the energy conversion performance. As a result, comparing to TiO2,the nanorod-likeZnO filmwas found to be a much better buffer layer that made the fill factor improve from a value of 0.60 for TBD to 0.82 for ZBD, and consequently thePCE was enhanced from 0.84 for TBD to 1.17% for ZBD.

  2. Atomic Layer Deposition of TiO2 for a High-Efficiency Hole-Blocking Layer in Hole-Conductor-Free Perovskite Solar Cells Processed in Ambient Air.

    PubMed

    Hu, Hang; Dong, Binghai; Hu, Huating; Chen, Fengxiang; Kong, Mengqin; Zhang, Qiuping; Luo, Tianyue; Zhao, Li; Guo, Zhiguang; Li, Jing; Xu, Zuxun; Wang, Shimin; Eder, Dominik; Wan, Li

    2016-07-20

    In this study we design and construct high-efficiency, low-cost, highly stable, hole-conductor-free, solid-state perovskite solar cells, with TiO2 as the electron transport layer (ETL) and carbon as the hole collection layer, in ambient air. First, uniform, pinhole-free TiO2 films of various thicknesses were deposited on fluorine-doped tin oxide (FTO) electrodes by atomic layer deposition (ALD) technology. Based on these TiO2 films, a series of hole-conductor-free perovskite solar cells (PSCs) with carbon as the counter electrode were fabricated in ambient air, and the effect of thickness of TiO2 compact film on the device performance was investigated in detail. It was found that the performance of PSCs depends on the thickness of the compact layer due to the difference in surface roughness, transmittance, charge transport resistance, electron-hole recombination rate, and the charge lifetime. The best-performance devices based on optimized TiO2 compact film (by 2000 cycles ALD) can achieve power conversion efficiencies (PCEs) of as high as 7.82%. Furthermore, they can maintain over 96% of their initial PCE after 651 h (about 1 month) storage in ambient air, thus exhibiting excellent long-term stability. PMID:27340730

  3. A low-cost, high-efficiency solar cell based on dye-sensitized colloidal TiO2 films

    NASA Astrophysics Data System (ADS)

    O'Regan, Brian; Graetzel, Michael

    1991-10-01

    A photovoltaic cell created from low- to medium-purity materials by low-cost processes is described which exhibits a commercially realistic energy-conversion efficiency. The device is based on a 10-micron thick optically transparent film of titanium dioxide particles a few nm in size, coated with a monolayer of a charge-transfer dye to sensitize the film for light harvesting. The device harvests a high proportion of the incident solar energy flux and shows exceptionally high efficiencies for the conversion of incident photons to electrical current. The overall light-to-electric energy conversion yield is 7.1-7.9 percent in simulated solar light and 12 percent in diffuse daylight. The large current densities and exceptional stability as well as the low cost make practical applications feasible.

  4. Dye adsorption mechanisms in TiO2 films, and their effects on the photodynamic and photovoltaic properties in dye-sensitized solar cells.

    PubMed

    Hwang, Kyung-Jun; Shim, Wang-Geun; Kim, Youngjin; Kim, Gunwoo; Choi, Chulmin; Kang, Sang Ook; Cho, Dae Won

    2015-09-14

    The adsorption mechanism for the N719 dye on a TiO2 electrode was examined by the kinetic and diffusion models (pseudo-first order, pseudo-second order, and intra-particle diffusion models). Among these methods, the observed adsorption kinetics are well-described using the pseudo-second order model. Moreover, the film diffusion process was the main controlling step of adsorption, which was analysed using a diffusion-based model. The photodynamic properties in dye-sensitized solar cells (DSSCs) were investigated using time-resolved transient absorption techniques. The photodynamics of the oxidized N719 species were shown to be dependent on the adsorption time, and also the adsorbed concentration of N719. The photovoltaic parameters (Jsc, Voc, FF and η) of this DSSC were determined in terms of the dye adsorption amounts. The solar cell performance correlates significantly with charge recombination and dye regeneration dynamics, which are also affected by the dye adsorption amounts. Therefore, the photovoltaic performance of this DSSC can be interpreted in terms of the adsorption kinetics and the photodynamics of oxidized N719.

  5. Enhanced photovoltaic performance of dye-sensitized solar cells based on NaYF4:Yb(3+), Er(3+)-incorporated nanocrystalline TiO2 electrodes.

    PubMed

    Zhu, Guang; Wang, Hongyan; Zhang, Quanxin; Zhang, Li

    2015-08-01

    Near infrared to visible up-conversion of light by rare earth ion-doped phosphors (NaYF4:Yb(3+), Er(3+)) that convert multiple photons of lower energy to higher energy photons offer new possibilities for improved performance of photovoltaic devices. Here, up-conversion phosphor NaYF4:Yb(3+), Er(3+) doped nanocrystalline TiO2 films are designed and used as a electrode for dye-sensitized solar cells, and the photovoltaic performance of DSSCs based on composite electrodes are investigated. The results show the cell with NaYF4:Yb(3+), Er(3+) achieves a power conversion efficiency of 7.65% under one sun illumination (AM 1.5G, 100mWcm(-2)), which is an increase of 14% compared to the cell without NaYF4:Yb(3+), Er(3+) (6.71%). The performance improvement is attributed to the dual effects of enhanced light harvesting from extended light absorption range and increased light scattering, and lower electron transfer resistance.

  6. Adsorption of organic dyes on TiO2 surfaces in dye-sensitized solar cells: interplay of theory and experiment.

    PubMed

    Anselmi, Chiara; Mosconi, Edoardo; Pastore, Mariachiara; Ronca, Enrico; De Angelis, Filippo

    2012-12-14

    First-principles computer simulations can contribute to a deeper understanding of the dye/semiconductor interface lying at the heart of Dye-sensitized Solar Cells (DSCs). Here, we present the results of simulation of dye adsorption onto TiO(2) surfaces, and of their implications for the functioning of the corresponding solar cells. We propose an integrated strategy which combines FT-IR measurements with DFT calculations to individuate the energetically favorable TiO(2) adsorption mode of acetic acid, as a meaningful model for realistic organic dyes. Although we found a sizable variability in the relative stability of the considered adsorption modes with the model system and the method, a bridged bidentate structure was found to closely match the FT-IR frequency pattern, also being calculated as the most stable adsorption mode by calculations in solution. This adsorption mode was found to be the most stable binding also for realistic organic dyes bearing cyanoacrylic anchoring groups, while for a rhodanine-3-acetic acid anchoring group, an undissociated monodentate adsorption mode was found to be of comparable stability. The structural differences induced by the different anchoring groups were related to the different electron injection/recombination with oxidized dye properties which were experimentally assessed for the two classes of dyes. A stronger coupling and a possibly faster electron injection were also calculated for the bridged bidentate mode. We then investigated the adsorption mode and I(2) binding of prototype organic dyes. Car-Parrinello molecular dynamics and geometry optimizations were performed for two coumarin dyes differing by the length of the π-bridge separating the donor and acceptor moieties. We related the decreasing distance of the carbonylic oxygen from the titania to an increased I(2) concentration in proximity of the oxide surface, which might account for the different observed photovoltaic performances. The interplay between theory

  7. First principles study of thieno[2,3-b]indole-based organic dyes for dye-sensitized solar cells: Screen novel π-linkers and explore the interface between photosensitizers and TiO2

    NASA Astrophysics Data System (ADS)

    Wen, Yaping; Wu, Wenpeng; Li, Yuanyuan; Zhang, Weiyi; Zeng, Zhaoyang; Wang, Li; Zhang, Jinglai

    2016-09-01

    Four organic compounds with different π-linkers are theoretically explored as potential photosensitizers for application in dye-sensitized solar cells (DSSCs). Besides the isolated dyes, the interfacial properties of dyes adsorbed on TiO2 anatase (101) surface are theoretically investigated. The overall conversion efficiency (η) of DSSCs is evaluated by the following items on the basis of the isolated dyes, including structures, absorption spectrum, energy gap, open-circuit voltage (Voc), short-circuit current density (Jsc), and reorganization energies (λtotal). After adsorbed on the TiO2 surface, the electron would be efficiently injected from dye into the TiO2 surface because of the increased of the lowest unoccupied molecular orbital (LUMO) energy level of the dyes, the decreased of the conduction band of TiO2 surface, and the narrowed band gaps for both dye and TiO2. Moreover, the injection times are in a reasonable range indicating that they are ideal dyes. Combination of all items, the performance of THI-2T-C (See Scheme 1, the sketch structures of all the investigated isolated dyes) stands out from the rest investigated dyes from the theoretical viewpoint. Only enlargement of the π-linker extent is not a smart choice, since the nature of π-linker plays a more important role in affecting the performance of DSSCs.

  8. Chemical reactions in TiO2/SnO2/TiCl4 hybrid electrodes and their impacts to power conversion efficiency of dye-sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Chou, Chuen-Shii; Jhang, Jhih-Wei; Chou, Sheng-Wei; Wu, Ping

    2015-01-01

    This study examined the applicability of TiO2/SnO2/TiCl4 hybrid electrodes in dye-sensitized solar cells (DSSCs) by combining chemical modeling with experimentation. The interfacial chemical reactions in a TiO2/SnO2/TiCl4 system were simulated using a thermochemistry software package, which led to the design and testing of hybrid working electrodes. Chemical thermodynamic modeling proved that TiCl4 is an effective agent in removing Tin+ (n<4) and Snm+ (m<4) ion impurities from dry-mixed TiO2/SnO2 composite particles. Our results demonstrate that the power conversion efficiency of DSSC with a TiO2/SnO2/TiCl4 hybrid electrode exceeds that of the conventional DSSC with a TiO2 electrode due to the effects of light-scattering and the formation of additional absorbance (SnCl2), which is an unexpected side effect of TiCl4 treatment enabling the absorption of visible light. The proposed approach is ideally suited to establishing relationships between chemistry theory and the structure and performance of advanced DSSCs as well as photo-electro-chemical systems.

  9. DC sputtering assisted nano-branched core-shell TiO2/ZnO electrodes for application in dye-sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Zhang, Zengming; Hu, Yong; Qin, Fuyu; Ding, Yutian

    2016-07-01

    TiO2/ZnO core-shell photo-anodes with a large surface area were synthesised by a combination of chemical growth and direct current (DC) magnetron sputtering (MS). The use of these combined methods for the advancement of dye-sensitized solar cells (DSSCs) was discussed. An understanding of the morphology and structure of this core-shell material was obtained from the use of scanning electron microscopy (SEM) and transmission electron microscopy (TEM). It was found that the thickness of the ZnO nanoshells (as assessed by using TEM), prepared by MS, has a significant effect on improvements in the conversion efficiency. The conversion efficiency can be greatly improved from 0.06% to 0.72% by optimising different experimental conditions, such as ZnO nanoshell MS time and chemical bath deposition time. The enhanced efficiency may be attributed to the emergence of a ZnO energy barrier and the improvement of the photo-anode surface area.

  10. Molecular Engineering, Photophysical and Electrochemical Characterizations of Novel Ru(II) and BODIPY Sensitizers for Mesoporous TiO2 Solar Cells

    NASA Astrophysics Data System (ADS)

    Cheema, Hammad Arshad

    To realize the dream of a low carbon society and ensure the wide spread application of renewable energy sources such as solar energy, photovoltaic devices should be highly efficient, cost-effective and stable for at least 20 years. Dye sensitized solar cells (DSCs) are photovoltaic cells that mimic the natural photosynthesis. In a DSC, the dye absorbs photons from incident light and converts those photons to electric charges, which are then extracted to the outer circuit through semiconductor TiO2, whereas the mediator regenerates the oxidized dye. A sensitizer is the pivotal component in the device in terms of determining the spectral response, color, photocurrent density, long term stability, and thickness of a DSC. The breakthrough report by O'Regan and Gratzel in 1991 has garnered more than 18,673 citations (as of October 9, 2014), which indicates the immense scientific interest to better understand and improve the fundamental science of this technology. With the aforementioned in mind, this study has focused on the molecular engineering of novel sensitizers to provide a better understanding of structure-property relationships of novel sensitizers for DSCs. The characterization of sensitizers (HD-1-mono, HD-2-mono and HD-2) for photovoltaic applications showed that the photocurrent response of DSCs can be increased by using mono-ancillary ligand instead of bis-ancillary ligands, which is of great commercial value considering the difference in the molecular weights of both dyes. The results of this work were published in Journal of Materials Chemistry A (doi:10.1039/c4ta01942c) and ACS Applied Materials and Interfaces (doi: 10.1021/am502400b). Furthermore, structure-property relationships were investigated in Ru (II) sensitizers HL-41 and HL-42 in order to elucidate the steric effects of electron donating ancillary ligands on photocurrent and photovoltage, as discussed in Chapter 4. It was found that the electron donating group (ethoxy) ortho to the CH=CH spacer

  11. Towards high efficiency air-processed near-infrared responsive photovoltaics: bulk heterojunction solar cells based on PbS/CdS core-shell quantum dots and TiO2 nanorod arrays.

    PubMed

    Gonfa, Belete Atomsa; Kim, Mee Rahn; Delegan, Nazar; Tavares, Ana C; Izquierdo, Ricardo; Wu, Nianqiang; El Khakani, My Ali; Ma, Dongling

    2015-06-14

    Near infrared (NIR) PbS quantum dots (QDs) have attracted significant research interest in solar cell applications as they offer several advantages, such as tunable band gaps, capability of absorbing NIR photons, low cost solution processability and high potential for multiple exciton generation. Nonetheless, reports on solar cells based on NIR PbS/CdS core-shell QDs, which are in general more stable and better passivated than PbS QDs and thus more promising for solar cell applications, remain very rare. Herein we report high efficiency bulk heterojunction QD solar cells involving hydrothermally grown TiO2 nanorod arrays and PbS/CdS core-shell QDs processed in air (except for a device thermal annealing step) with a photoresponse extended to wavelengths >1200 nm and with a power conversion efficiency (PCE) as high as 4.43%. This efficiency was achieved by introducing a thin, sputter-deposited, uniform TiO2 seed layer to improve the interface between the TiO2 nanorod arrays and the front electrode, by optimizing TiO2 nanorod length and by conducting QD annealing treatment to enhance charge carrier transport. It was found that the effect of the seed layer became more obvious when the TiO2 nanorods were longer. Although photocurrent did not change much, both open circuit voltage and fill factor clearly changed with TiO2 nanorod length. This was mainly attributed to the variation of charge transport and recombination processes, as evidenced by series and shunt resistance studies. The optimal PCE was obtained at the nanorod length of ∼450 nm. Annealing is shown to further increase the PCE by ∼18%, because of the improvement of charge carrier transport in the devices as evidenced by considerably increased photocurrent. Our results clearly demonstrate the potential of the PbS/CdS core-shell QDs for the achievement of high PCE, solution processable and NIR responsive QD solar cells.

  12. Enhanced performance of dye-sensitized solar cells based on organic dopant incorporated PVDF-HFP/PEO polymer blend electrolyte with g-C3N4/TiO2 photoanode

    NASA Astrophysics Data System (ADS)

    Senthil, R. A.; Theerthagiri, J.; Madhavan, J.; Murugan, K.; Arunachalam, Prabhakarn; Arof, A. K.

    2016-10-01

    This work describes the effect of 2-aminopyrimidine (2-APY) on poly(vinylidinefluoride-co-hexafluoropropylene) (PVDF-HFP)/polyethylene oxide (PEO) blend polymer electrolyte along with binary iodide salts (tetrabutylammonium iodide (TBAI) and potassium iodide (KI)) and iodine (I2) were studied for enhancing the efficiency of the dye-sensitized solar cells (DSSCs) consisting of g-C3N4/TiO2 composite as photoanode. The g-C3N4 was synthesized from low cost urea by thermal condensation method. It was used as a precursor to synthesize the various weight percentage ratios (5%, 10% and 15%) of g-C3N4/TiO2 composites by wet-impregnation method. The pure and 2-APY incorporated PVDF-HFP/PEO polymer blend electrolytes were arranged by wet chemical process (casting method) using DMF as a solvent. The synthesized g-C3N4/TiO2 composites and polymer blend electrolytes were studied and analyzed by Fourier transform infrared (FT-IR) spectroscopy, X-ray diffractometer (XRD) and scanning electron microscopy (SEM). The ionic conductivity values of the pure and 2-APY incorporated PVDF-HFP/PEO blend electrolytes were estimated to be 4.53×10-5 and 1.87×10-4 Scm-1 respectively. The UV-vis absorption spectroscopy was carried out for the pure and different wt% of g-C3N4/TiO2 composites coated FTO films after N3 dye-sensitization. The 10 wt% g-C3N4/TiO2 composite film showed a maximum absorption compared to the others. The DSSC assembled with 10 wt% g-C3N4/TiO2 as photoanode using the pure polymer blend electrolyte exhibited a power conversion efficiency (PCE) of 3.17% , which was superior than that of DSSC based pure TiO2 (2.46%). However, the PCE was increased to 4.73% for the DSSC assembled using 10 wt% g-C3N4/TiO2 as photoanode with 2-APY incorporated polymer blend electrolyte. Hence, the present study is a successful attempt to provide a new pathway to enhance the performance of DSSCs.

  13. Effects of calcination treatment on the morphology, crystallinity, and photoelectric properties of all-solid-state dye-sensitized solar cells assembled by TiO2 nanorod arrays.

    PubMed

    Sun, Xianmiao; Sun, Qiong; Li, Yang; Sui, Lina; Dong, Lifeng

    2013-11-14

    TiO2 has been extensively investigated due to its unique photoelectric properties. In this study, oriented single-crystal rutile TiO2 nanorod arrays were synthesized and then calcined at different temperatures in the atmosphere. The morphology and crystalline characterization indicated that the length of TiO2 nanorods increased rapidly and the nanorods became aggregated and fragile after calcination, yet the sintering treatment seemed to have almost no effect on the crystallinity. To obtain the all-solid-state, dye-sensitized solar cells (DSSCs), a newly reported solid inorganic semiconductor, CsSnI2.95F0.05, was employed as the electrolyte, and the Pt deposited on the conductive side of the fluorine-doped tin oxide (FTO) glass substrate was used as the counter-electrode. The effects of the calcination treatment on the photoelectric properties of the solar cells, including external quantum efficiency (EQE), open circuit voltage (V(OC)), short-circuit current (J(SC)), and photoelectric conversion efficiency (η), were investigated under the illumination of a solar simulator. As a result, all of the EQE, V(OC), J(SC), and η values of the cells first increased and then declined with the increase of calcination temperatures, and the highest η of 2.81% was obtained by the cell assembled with its TiO2 electrode sintered at 450 °C for 3 h, a value almost 2.5 times that of the non-sintered sample (1.1%).

  14. Photosensitizing activity of ferrocenyl bearing Ni(II) and Cu(II) dithiocarbamates in dye sensitized TiO2 solar cells.

    PubMed

    Singh, Vikram; Chauhan, Ratna; Gupta, Ajit N; Kumar, Vinod; Drew, Michael G B; Bahadur, Lal; Singh, Nanhai

    2014-03-28

    Biferrocene bearing planar metal dithiocarbamates, namely, [M(FcCH2dtc)2] (dtc = furan-2-ylmethyldithiocarbamate, M = Cu(II) 1, Ni(II) 4; dtc = benzo[d][1,3]dioxol-5-ylmethyl dithiocarbamate, M = Cu(II) 2, Ni(II) 5; dtc = pyridin-2-ylmethyldithiocarbamate, M = Cu(II) 3, Ni(II) 6; Fc = ferrocenyl; Fe(η(5)-C5H5)(η(5)-C5H4-)), have been synthesized and characterized by microanalysis, magnetic susceptibility and cyclic voltammetry. Structures of 1, 2 and 4 have been obtained by single crystal X-ray diffraction. These complexes with pyridyl, piperonyl and furfuryl as heteroaromatic groups in the dithiocarbamate ligands have been exploited as sensitizers in dye sensitized TiO2 solar cells for converting sunlight into electrical energy. Light-to-electrical energy conversion efficiencies achieved using these sensitizers are considerably greater than those obtained with analogous compounds previously reported by us. The overall conversion efficiency (η) is found to be dependent upon the nature of the heteroaromatic conjugated linkers and increases in the order η (ferrocenylfurfuryl) > η (ferrocenylpiperonyl) > η (ferrocenylpyridyl) all values being lower than that obtained in the reference Ru dye N719 under similar experimental conditions. The conversion efficiencies also vary with the metal being higher for Ni (4, 5 and 6) than for Cu complexes (1, 2 and 3). The X-ray structural analyses reveal the existence of rare M···H-C intermolecular anagostic interactions involving the metal atom in chain motifs in 1 and 4, which are retained in solution as evidenced by (1)H NMR spectroscopy. PMID:24473675

  15. Photocatalyzed degradation of flumequine by doped TiO2 and simulated solar light.

    PubMed

    Nieto, J; Freer, J; Contreras, D; Candal, R J; Sileo, E E; Mansilla, H D

    2008-06-30

    Titanium dioxide was obtained in its pure form (TiO2) and in the presence of urea (u-TiO2) and thiourea (t-TiO2) using the sol-gel technique. The obtained powders were characterized by BET surface area analysis, Infrared Spectroscopy, Diffuse Reflectance Spectroscopy and the Rietveld refinement of XRD measurements. All the prepared catalysts show high anatase content (>99%). The a and b-cell parameters of anatase increase in the order TiO2cell dimensions, the cell grows thicker and shorter when prepared in the presence of urea and thiourea, respectively. The cell volume decreases in the order t-TiO2>u-TiO2>TiO2. The photocatalytic activities of the samples were determined on flumequine under solar-simulated irradiation. The most active catalysts were u-TiO2 and t-TiO2, reaching values over 90% of flumequine degradation after 15 min irradiation, compared with values of 55% for the pure TiO2 catalyst. Changing simultaneously the catalyst amount (t-TiO2) and pH, multivariate analysis using the response surface methodology was used to determine the roughly optimal conditions for flumequine degradation. The optimized conditions found were pH below 7 and a catalyst amount of 1.6 g L(-1).

  16. Deliberate Design of TiO2 Nanostructures towards Superior Photovoltaic Cells.

    PubMed

    Sun, Ziqi; Liao, Ting; Sheng, Liyuan; Kou, Liangzhi; Kim, Jung Ho; Dou, Shi Xue

    2016-08-01

    TiO2 nanostructures are being sought after as flexibly utilizable building blocks for the fabrication of the mesoporous thin-film photoelectrodes that are the heart of the third-generation photovoltaic devices, such as dye-sensitized solar cells (DSSCs), quantum-dot-sensitized solar cells (QDSSCs), and the recently promoted perovskite-type solar cells. Here, we report deliberate tailoring of TiO2 nanostructures for superior photovoltaic cells. Morphology engineering of TiO2 nanostructures is realized by designing synthetic protocols in which the precursor hydrolysis, crystal growth, and oligomer self-organization are precisely controlled. TiO2 nanostructures in forms varying from isolated nanocubes, nanorods, and cross-linked nanorods to complex hierarchical structures and shape-defined mesoporous micro-/nanostructures were successfully synthesized. The photoanodes made from the shape-defined mesoporous TiO2 microspheres and nanospindles presented superior performances, owing to the well-defined overall shapes and the inner ordered nanochannels, which allow not only a high amount of dye uptake, but also improved visible-light absorption. This study provides a new way to seek an optimal synthetic protocol to meet the required functionality of the nanomaterials. PMID:27381513

  17. Deliberate Design of TiO2 Nanostructures towards Superior Photovoltaic Cells.

    PubMed

    Sun, Ziqi; Liao, Ting; Sheng, Liyuan; Kou, Liangzhi; Kim, Jung Ho; Dou, Shi Xue

    2016-08-01

    TiO2 nanostructures are being sought after as flexibly utilizable building blocks for the fabrication of the mesoporous thin-film photoelectrodes that are the heart of the third-generation photovoltaic devices, such as dye-sensitized solar cells (DSSCs), quantum-dot-sensitized solar cells (QDSSCs), and the recently promoted perovskite-type solar cells. Here, we report deliberate tailoring of TiO2 nanostructures for superior photovoltaic cells. Morphology engineering of TiO2 nanostructures is realized by designing synthetic protocols in which the precursor hydrolysis, crystal growth, and oligomer self-organization are precisely controlled. TiO2 nanostructures in forms varying from isolated nanocubes, nanorods, and cross-linked nanorods to complex hierarchical structures and shape-defined mesoporous micro-/nanostructures were successfully synthesized. The photoanodes made from the shape-defined mesoporous TiO2 microspheres and nanospindles presented superior performances, owing to the well-defined overall shapes and the inner ordered nanochannels, which allow not only a high amount of dye uptake, but also improved visible-light absorption. This study provides a new way to seek an optimal synthetic protocol to meet the required functionality of the nanomaterials.

  18. Arginine Interactions with Anatase TiO2 (100) Surface and the Perturbation of 49Ti NMR Chemical Shifts - A DFT Investigation: Relevance to Renu-Seeram Bio Solar Cell

    SciTech Connect

    Koch, Rainer; Lipton, Andrew S.; Filipek, S.; Renugopalakrishnan, Venkatesan M.

    2011-06-01

    Density functional theoretical calculations have been utilized to investigate the interaction of the amino acid arginine with the (100) surface of anatase and the reproduction of experimentally measured 49Ti NMR chemical shifts of anatase. Significant binding of arginine through electrostatic interaction and hydrogen bonds of the arginine guanidinium protons to the TiO2 surface oxygen atoms is observed, allowing attachment of proteins to titania surfaces in the construction of bio-sensitized solar cells. GIAO-B3LYP/6-31G(d) NMR calculation of a three-layer model based on the experimental structure of this TiO2 modification gives an excellent reproduction of the experimental value (-927 ppm) within +/- 7 ppm, however, the change in relative chemical shifts, EFGs and CSA suggest that the effect of the electrostatic arginine binding might be too small for experimental detection.

  19. Effects of TiO2 and TiC Nanofillers on the Performance of Dye Sensitized Solar Cells Based on the Polymer Gel Electrolyte of a Cobalt Redox System.

    PubMed

    Venkatesan, Shanmuganathan; Liu, I-Ping; Chen, Li-Tung; Hou, Yi-Chen; Li, Chiao-Wei; Lee, Yuh-Lang

    2016-09-21

    Polymer gel electrolytes (PGEs) of cobalt redox system are prepared for dye sensitized solar cell (DSSC) applications. Poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) is used as a gelator of an acetonitrile (ACN) liquid electrolyte containing tris(2,2'-bipyridine)cobalt(II/III) redox couple. Titanium dioxide (TiO2) and titanium carbide (TiC) nanoparticles are utilized as nanofillers (NFs) of this PGE, and the effects of the two NFs on the conductivity of the PGEs, charge-transfer resistances at the electrode/PGE interface, and the performance of the gel-state DSSCs are studied and compared. The results show that the presence of TiC NFs significantly increases the conductivity of the PGE and decreases the charge-transfer resistance at the Pt counter-electrode (CE)/PGE interface. Therefore, the gel-state DSSC utilizing TiC NFs can achieve a conversion efficiency (6.29%) comparable to its liquid counterpart (6.30%), and, furthermore, the cell efficiency can retain 94% of its initial value after a 1000 h stability test at 50 °C. On the contrary, introduction of TiO2 NFs in the PGE causes a decrease of cell performances. It shows that the presence of TiO2 NFs increases the charge-transfer resistance at the Pt CE/PGE interface, induces the charge recombination at the photoanode/PGE interface, and, furthermore, causes a dye desorption in a long-term-stability test. These results are different from those reported for the iodide redox system and are ascribed to a specific attractive interaction between TiO2 and cobalt redox ions.

  20. Effects of TiO2 and TiC Nanofillers on the Performance of Dye Sensitized Solar Cells Based on the Polymer Gel Electrolyte of a Cobalt Redox System.

    PubMed

    Venkatesan, Shanmuganathan; Liu, I-Ping; Chen, Li-Tung; Hou, Yi-Chen; Li, Chiao-Wei; Lee, Yuh-Lang

    2016-09-21

    Polymer gel electrolytes (PGEs) of cobalt redox system are prepared for dye sensitized solar cell (DSSC) applications. Poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) is used as a gelator of an acetonitrile (ACN) liquid electrolyte containing tris(2,2'-bipyridine)cobalt(II/III) redox couple. Titanium dioxide (TiO2) and titanium carbide (TiC) nanoparticles are utilized as nanofillers (NFs) of this PGE, and the effects of the two NFs on the conductivity of the PGEs, charge-transfer resistances at the electrode/PGE interface, and the performance of the gel-state DSSCs are studied and compared. The results show that the presence of TiC NFs significantly increases the conductivity of the PGE and decreases the charge-transfer resistance at the Pt counter-electrode (CE)/PGE interface. Therefore, the gel-state DSSC utilizing TiC NFs can achieve a conversion efficiency (6.29%) comparable to its liquid counterpart (6.30%), and, furthermore, the cell efficiency can retain 94% of its initial value after a 1000 h stability test at 50 °C. On the contrary, introduction of TiO2 NFs in the PGE causes a decrease of cell performances. It shows that the presence of TiO2 NFs increases the charge-transfer resistance at the Pt CE/PGE interface, induces the charge recombination at the photoanode/PGE interface, and, furthermore, causes a dye desorption in a long-term-stability test. These results are different from those reported for the iodide redox system and are ascribed to a specific attractive interaction between TiO2 and cobalt redox ions. PMID:27563731

  1. Parameters Affecting I-V Hysteresis of CH3NH3PbI3 Perovskite Solar Cells: Effects of Perovskite Crystal Size and Mesoporous TiO2 Layer.

    PubMed

    Kim, Hui-Seon; Park, Nam-Gyu

    2014-09-01

    Current-voltage (I-V) characteristics of CH3NH3PbI3 perovskite solar cells are studied using a time-dependent current response with stepwise sweeping of the bias voltage. Compared with the crystalline Si solar cell showing time-independent current at a given bias voltage, the perovskite solar cells exhibit time-dependent current response. The current increases with time and becomes steady at forward scan from short-circuit to open-circuit, whereas it is decayed and saturated with time at reverse scan from open-circuit to short-circuit. Time-dependent current response eventually leads to I-V hysteresis depending on the scan direction and the scan rate. Crystal size of CH3NH3PbI3 and the mesoporous TiO2 (mp-TiO2) film are found to influence I-V hysteresis, where the I-V hysteresis is alleviated as crystal size increases and in the presence of mp-TiO2. The capacitance observed at low frequency (0.1 to 1 Hz), associated with dipole polarization, tends to diminish as size of perovskite and mp-TiO2 layer thickness increases, which suggests that the origin of hysteresis correlates to the capacitive characteristic of CH3NH3PbI3 and the degree of hysteresis depends strongly on perovskite crystal size and mesoporous TiO2 layer.

  2. Solar-driven photocatalytic treatment of diclofenac using immobilized TiO2-based zeolite composites.

    PubMed

    Kovacic, Marin; Salaeh, Subhan; Kusic, Hrvoje; Suligoj, Andraz; Kete, Marko; Fanetti, Mattia; Stangar, Urska Lavrencic; Dionysiou, Dionysios D; Bozic, Ana Loncaric

    2016-09-01

    The study is aimed at evaluating the potential of immobilized TiO2-based zeolite composite for solar-driven photocatalytic water treatment. In that purpose, TiO2-iron-exchanged zeolite (FeZ) composite was prepared using commercial Aeroxide TiO2 P25 and iron-exchanged zeolite of ZSM5 type, FeZ. The activity of TiO2-FeZ, immobilized on glass support, was evaluated under solar irradiation for removal of diclofenac (DCF) in water. TiO2-FeZ immobilized in a form of thin film was characterized for its morphology, structure, and composition using scanning electron microscopy/energy-dispersive x-ray spectroscopy (SEM/EDX). Diffuse reflectance spectroscopy (DRS) was used to determine potential changes in band gaps of prepared TiO2-FeZ in comparison to pure TiO2. The influence of pH, concentration of hydrogen peroxide, FeZ wt% within the composite, and photocatalyst dosage on DCF removal and conversion efficiency by solar/TiO2-FeZ/H2O2 process was investigated. TiO2-FeZ demonstrated higher photocatalytic activity than pure TiO2 under solar irradiation in acidic conditions and presence of H2O2.

  3. Solar-driven photocatalytic treatment of diclofenac using immobilized TiO2-based zeolite composites.

    PubMed

    Kovacic, Marin; Salaeh, Subhan; Kusic, Hrvoje; Suligoj, Andraz; Kete, Marko; Fanetti, Mattia; Stangar, Urska Lavrencic; Dionysiou, Dionysios D; Bozic, Ana Loncaric

    2016-09-01

    The study is aimed at evaluating the potential of immobilized TiO2-based zeolite composite for solar-driven photocatalytic water treatment. In that purpose, TiO2-iron-exchanged zeolite (FeZ) composite was prepared using commercial Aeroxide TiO2 P25 and iron-exchanged zeolite of ZSM5 type, FeZ. The activity of TiO2-FeZ, immobilized on glass support, was evaluated under solar irradiation for removal of diclofenac (DCF) in water. TiO2-FeZ immobilized in a form of thin film was characterized for its morphology, structure, and composition using scanning electron microscopy/energy-dispersive x-ray spectroscopy (SEM/EDX). Diffuse reflectance spectroscopy (DRS) was used to determine potential changes in band gaps of prepared TiO2-FeZ in comparison to pure TiO2. The influence of pH, concentration of hydrogen peroxide, FeZ wt% within the composite, and photocatalyst dosage on DCF removal and conversion efficiency by solar/TiO2-FeZ/H2O2 process was investigated. TiO2-FeZ demonstrated higher photocatalytic activity than pure TiO2 under solar irradiation in acidic conditions and presence of H2O2. PMID:27255319

  4. Polyol thermolysis synthesis of TiO2 nanoparticles and its paste formulation to fabricate photoanode for dye-sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Pratheep, P.; Vijayakumar, E.; Subramania, A.

    2015-05-01

    Titanium dioxide (TiO2) nanoparticles (NPs) were prepared by a simple polyol thermolysis process using various mole ratios of titanium tetrachloride (TiCl4) and polyvinylpyrrolidone (PVP). The prepared TiO2 NPs were characterized by TG/DTA, XRD, SEM, and BET analysis. The TiO2 NPs obtained using 0.1 M of TiCl4 and 0.02 M of PVP have high surface area with lesser particles size than the same obtained using 0.1 M of TiCl4 with other mole ratios of PVP. The high surface area TiO2 NPs were used to formulate TiO2 paste. The impact of ethyl cellulose, terpineol, and dibutyl phthalate in the formulation of TiO2 paste was optimized with respect to standard TiO2 paste ( Dyesol Ltd.) on the adsorption of dye was studied by UV-Vis spectroscopy. The photovoltaic performance of DSSCs fabricated using the formulated TiO2 paste has achieved 97.83 % of power conversion efficiency (PCE) (η = 4.5 %) with respect to the standard TiO2 paste ( Dyesol Ltd.) and its PCE were found to be 4.6 % (η). This PCE value was nearly closer to that of the same DSSC fabricated using the standard TiO2 paste ( Dyesol Ltd.) and higher than the P25 TiO2 ( Degussa) paste and its achieved PCE were found to be 86.04 %.

  5. Polymer-Based Ruthenium(II) Polypyridyl Chromophores on TiO2 for Solar Energy Conversion.

    PubMed

    Leem, Gyu; Morseth, Zachary A; Wee, Kyung-Ryang; Jiang, Junlin; Brennaman, M Kyle; Papanikolas, John M; Schanze, Kirk S

    2016-04-20

    A polychromophoric light-harvesting assembly featuring a polystyrene (PS) backbone with ionic carboxylate-functionalized Ru(II) polypyridyl complexes as pendant groups (PS-Ru-A) was synthesized and successfully anchored onto mesoporous structured TiO2 films (TiO2 //PS-Ru-A). Studies of the resulting TiO2 //PS-Ru-A films carried out by transmission electron microscopy (TEM), scanning electron microscopy (SEM), and atomic force microscopy (AFM) confirmed that the ionic carboxylated Ru(II) complexes from PS-Ru-A led to the surface immobilization on the TiO2 film. Monochromatic light photocurrent spectroscopy (IPCE) and white light (AM1.5G) current-voltage studies of dye-sensitized solar cells using the TiO2 //PS-Ru-A photoanode give rise to modest photocurrent and white light efficiency (24 % peak IPCE and 0.33 % PCE, respectively). The photostability of surface-bound TiO2 //PS-Ru-A films was tested and compared to a monomeric Ru(II) complex (TiO2 //Ru-A), showing an enhancement of ∼14 % in the photostability of PS-Ru-A. Transient absorption measurements reveal that electron injection from surface-bound pendants occurs on the picosecond time scale, similar to TiO2 //Ru-A, while time-resolved emission measurements reveal delayed electron injection occurring in TiO2 //PS-Ru-A on the nanosecond time scale, underscoring energy transport from unbound to surface-bound complexes. Additionally, charge recombination is delayed in PS-Ru-A, pointing towards intra-assembly hole transport to complexes away from the surface. Molecular dynamics simulations of PS-Ru-A in fluid solution indicate that a majority of the pendant Ru(II) complexes lie within 10-20 Å of each other, facilitating efficient energy- and charge transport among the pendant complexes.

  6. Effect of solvents on the extraction of natural pigments and adsorption onto TiO2 for dye-sensitized solar cell applications

    NASA Astrophysics Data System (ADS)

    Al-Alwani, Mahmoud A. M.; Mohamad, Abu Bakar; Kadhum, Abd. Amir H.; Ludin, Norasikin A.

    2015-03-01

    Nine solvents, namely, n-hexane, ethanol, acetonitrile, chloroform, ethyl-ether, ethyl-acetate, petroleum ether, n-butyl alcohol, and methanol were used to extract natural dyes from Cordyline fruticosa, Pandannus amaryllifolius and Hylocereus polyrhizus. To improve the adsorption of dyes onto the TiO2 particles, betalain and chlorophyll dyes were mixed with methanol or ethanol and water at various ratios. The adsorption of the dyes mixed with titanium dioxide (TiO2) was also observed. The highest adsorption of the C.fruticosa dye mixed with TiO2 was achieved at ratio 3:1 of methanol: water. The highest adsorption of P.amaryllifolius dye mixed with TiO2 was observed at 2:1 of ethanol: water. H.polyrhizus dye extracted by water and mixed with TiO2 demonstrated the highest adsorption among the solvents. All extracted dye was adsorbed onto the surface of TiO2 based on Fourier Transform Infrared Spectroscopy (FTIR) analysis. The inhibition of crystallinity of TiO2 was likewise investigated by X-ray analysis. The morphological properties and composition of dyes were analyzed via SEM and EDX.

  7. Effect of solvents on the extraction of natural pigments and adsorption onto TiO2 for dye-sensitized solar cell applications.

    PubMed

    Al-Alwani, Mahmoud A M; Mohamad, Abu Bakar; Kadhum, Abd Amir H; Ludin, Norasikin A

    2015-03-01

    Nine solvents, namely, n-hexane, ethanol, acetonitrile, chloroform, ethyl-ether, ethyl-acetate, petroleum ether, n-butyl alcohol, and methanol were used to extract natural dyes from Cordyline fruticosa, Pandannus amaryllifolius and Hylocereus polyrhizus. To improve the adsorption of dyes onto the TiO2 particles, betalain and chlorophyll dyes were mixed with methanol or ethanol and water at various ratios. The adsorption of the dyes mixed with titanium dioxide (TiO2) was also observed. The highest adsorption of the C.fruticosa dye mixed with TiO2 was achieved at ratio 3:1 of methanol: water. The highest adsorption of P.amaryllifolius dye mixed with TiO2 was observed at 2:1 of ethanol: water. H.polyrhizus dye extracted by water and mixed with TiO2 demonstrated the highest adsorption among the solvents. All extracted dye was adsorbed onto the surface of TiO2 based on Fourier Transform Infrared Spectroscopy (FTIR) analysis. The inhibition of crystallinity of TiO2 was likewise investigated by X-ray analysis. The morphological properties and composition of dyes were analyzed via SEM and EDX.

  8. Defect chemistry and defect engineering of TiO2-based semiconductors for solar energy conversion.

    PubMed

    Nowotny, Janusz; Alim, Mohammad Abdul; Bak, Tadeusz; Idris, Mohammad Asri; Ionescu, Mihail; Prince, Kathryn; Sahdan, Mohd Zainizan; Sopian, Kamaruzzaman; Mat Teridi, Mohd Asri; Sigmund, Wolfgang

    2015-12-01

    This tutorial review considers defect chemistry of TiO2 and its solid solutions as well as defect-related properties associated with solar-to-chemical energy conversion, such as Fermi level, bandgap, charge transport and surface active sites. Defect disorder is discussed in terms of defect reactions and the related charge compensation. Defect equilibria are used in derivation of defect diagrams showing the effect of oxygen activity and temperature on the concentration of both ionic and electronic defects. These defect diagrams may be used for imposition of desired semiconducting properties that are needed to maximize the performance of TiO2-based photoelectrodes for the generation of solar hydrogen fuel using photo electrochemical cells (PECs) and photocatalysts for water purification. The performance of the TiO2-based semiconductors is considered in terms of the key performance-related properties (KPPs) that are defect related. It is shown that defect engineering may be applied for optimization of the KPPs in order to achieve optimum performance. PMID:26446476

  9. Graphene-embedded 3D TiO2 inverse opal electrodes for highly efficient dye-sensitized solar cells: morphological characteristics and photocurrent enhancement.

    PubMed

    Kim, Hye-Na; Yoo, Haemin; Moon, Jun Hyuk

    2013-05-21

    We demonstrated the preparation of graphene-embedded 3D inverse opal electrodes for use in DSSCs. The graphene was incorporated locally into the top layers of the inverse opal structures and was embedded into the TiO2 matrix via post-treatment of the TiO2 precursors. DSSCs comprising the bare and 1-5 wt% graphene-incorporated TiO2 inverse opal electrodes were compared. We observed that the local arrangement of graphene sheets effectively enhanced electron transport without significantly reducing light harvesting by the dye molecules. A high efficiency of 7.5% was achieved in DSSCs prepared with the 3 wt% graphene-incorporated TiO2 inverse opal electrodes, constituting a 50% increase over the efficiencies of DSSCs prepared without graphene. The increase in efficiency was mainly attributed to an increase in J(SC), as determined by the photovoltaic parameters and the electrochemical impedance spectroscopy analysis. PMID:23536037

  10. Improved conversion efficiency of Ag2S quantum dot-sensitized solar cells based on TiO2 nanotubes with a ZnO recombination barrier layer

    PubMed Central

    2011-01-01

    We improve the conversion efficiency of Ag2S quantum dot (QD)-sensitized TiO2 nanotube-array electrodes by chemically depositing ZnO recombination barrier layer on plain TiO2 nanotube-array electrodes. The optical properties, structural properties, compositional analysis, and photoelectrochemistry properties of prepared electrodes have been investigated. It is found that for the prepared electrodes, with increasing the cycles of Ag2S deposition, the photocurrent density and the conversion efficiency increase. In addition, as compared to the Ag2S QD-sensitized TiO2 nanotube-array electrode without the ZnO layers, the conversion efficiency of the electrode with the ZnO layers increases significantly due to the formation of efficient recombination layer between the TiO2 nanotube array and electrolyte. PMID:21777458

  11. Graphene-embedded 3D TiO2 inverse opal electrodes for highly efficient dye-sensitized solar cells: morphological characteristics and photocurrent enhancement.

    PubMed

    Kim, Hye-Na; Yoo, Haemin; Moon, Jun Hyuk

    2013-05-21

    We demonstrated the preparation of graphene-embedded 3D inverse opal electrodes for use in DSSCs. The graphene was incorporated locally into the top layers of the inverse opal structures and was embedded into the TiO2 matrix via post-treatment of the TiO2 precursors. DSSCs comprising the bare and 1-5 wt% graphene-incorporated TiO2 inverse opal electrodes were compared. We observed that the local arrangement of graphene sheets effectively enhanced electron transport without significantly reducing light harvesting by the dye molecules. A high efficiency of 7.5% was achieved in DSSCs prepared with the 3 wt% graphene-incorporated TiO2 inverse opal electrodes, constituting a 50% increase over the efficiencies of DSSCs prepared without graphene. The increase in efficiency was mainly attributed to an increase in J(SC), as determined by the photovoltaic parameters and the electrochemical impedance spectroscopy analysis.

  12. Impedance analysis for dye-sensitized solar cells based on TiO2 electrode coated with Cr2O3

    NASA Astrophysics Data System (ADS)

    Li, Y.; Zhuang, Q. C.; Wang, H. T.; Xu, X. Q.; Qiang, Y. H.; Fang, L.

    2013-09-01

    TiO2 nanomaterial with typical anatase was prepared by hydrothermal method. A surface modification method was carried out by dip TiO2 electrode into Cr(NO3)3 solution. The TiO2/Cr2O3 thin film was characterized by X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM). The current-voltage (I-V) curve revealed that short circuit current and photoelectric transfer efficiency of the modified electrode enhanced by 19.3% and 21%, respectively. The main features of electrochemical impedance spectroscopy (EIS) were discussed in a wide range of potential applied. The parameters of electron transport resistance in TiO2 film (Rw), the overall charge transfer resistance (Rct) and capacitance (Cfilm) of film were analyzed using an equivalent circuit. It was found that Rw, Rct and Cfilm switch to exponential behavior at high bias.

  13. Improved photoanode structure based on anodic titania nanotube array covered by TiO2-NPs/nanographite composite layer for ETA-cells

    NASA Astrophysics Data System (ADS)

    Gavrilin, I. M.; Dronov, A. A.; Shilyaeva, Yu I.; Lebedev, E. A.; Kuzmicheva, M. S.; Savchuk, T. P.; Gavrilov, S. A.

    2016-08-01

    This work is devoted to the morphology and electrical properties optimization of flexible photoanodes based on anodic titanium oxide nanotubular arrays (TiO2-NTAs) for solar cells with extremely thin absorbing layer (ETA-cells) by TiO2-nanographite thin composite layer formation on the TiO2-NTAs surface. First, the carbon doped TiO2-NTAs were synthesized by annealing of the as-anodized TiO2-NTAs in argon without foreign carbonaceous precursor. The residual ethylene glycol absorbed on the nanotube wall during anodization serves as the carbon source and the C species are uniformly distributed along the entire nanotube to form the C-TiO2 NTAs. Further decorating of C-TiO2-NTAs surface by TiO2 nanoparticles to form the TiO2-nanographite (NG) composite layer with high conductivity and increased photoanode effective area showed improved ETA-cells performance.

  14. The role of surface modification for TiO2 nanoparticles in cancer cells.

    PubMed

    Xie, Jin; Pan, Xiaobo; Wang, Mengyan; Ma, Jiong; Fei, Yiyan; Wang, Pei-Nan; Mi, Lan

    2016-07-01

    Titanium dioxide nanoparticles (TiO2 NPs) have a potential in the field of biological application. However, its poor dispersibility in water hampered its applications. In this study, 3-phosphonopropionic acid and 3-aminopropyl-triethoxysilane were respectively used for surface modification on TiO2 NPs with negative and positive surface charges (denoted as TiO2-COOH and TiO2-NH2). Zeta potentials of the prepared samples with high absolute value demonstrate the great improvement in their dispersibility. In terms of viability experiment, both TiO2-COOH and TiO2-NH2 showed low cytotoxicity. The cellular uptake efficiency and the uptake pathways of TiO2-COOH and TiO2-NH2 for cancer cells were studied. The exocytosis of TiO2-NH2 was also observed in the experiment. PMID:27003465

  15. Preparation of Carbon-Doped TiO2 and Its Application as a Photoelectrodes in Dye-Sensitized Solar Cells.

    PubMed

    Park, Su Kyung; Jeong, Jin Seong; Yun, Tae Kwan; Bae, Jae Young

    2015-02-01

    In this study, C-doped TiO2 particles were successfully synthesized by a hydrothermal method. Three binding energy peaks were observed at 284.6, 286.2, and 288.5 eV in the C is region of the XPS. The signals at 286.2 and 288.5 eV were attributed to chemically bound C-O and Ti-C-O linkages within the crystalline TiO2 lattice, respectively. The introduction of carbon did not affect the crystallite structure or BET surface area of TiO2. The JSC value of DSSCs based on a C-doped TiO2 electrode was increased by 20% compared to DSSCs using a pure TiO2 electrode, and the energy conversion efficiency was increased by 23%. This was due to the enhancement of dye adsorption and high electrical conductivity of the carbon. High energy conversion efficiency was achieved with the DSSCs based on the C-doped TiC2 electrode.

  16. Electrodeposited ZnO thin film as an efficient alternative blocking layer for TiCl4 pre-treatment in TiO2-based dye sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Kouhestanian, E.; Mozaffari, S. A.; Ranjbar, M.; SalarAmoli, H.; Armanmehr, M. H.

    2016-08-01

    Recently, ZnO nanostructures have received considerable attention in fabrication of dye sensitized solar cell (DSSC) photoanodes due to their unique transport properties. In the present study, a chronoamperometric method was performed to fabricate the ZnO nanostructures as an appropriate alternative of TiCl4 pre-treatment to reduce the recombination reactions, while retaining the TiO2-based DSSC performance. The effect of polyvinyl alcohol (PVA) on ZnO electrodeposition to control the growth and crystallization of ZnO nanostructures was investigated. ZnO/TiO2 based-DSSCs were fabricated using N719 ruthenium dye and all photovoltaic parameters were characterized. Incident photon to current efficiency (IPCE), electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV) and VOC decay techniques were employed for studying the cell properties which is resulted in a significant enhancement in cell performance.

  17. Full Printable Processed Mesoscopic CH3NH3PbI3/TiO2 Heterojunction Solar Cells with Carbon Counter Electrode

    PubMed Central

    Ku, Zhiliang; Rong, Yaoguang; Xu, Mi; Liu, Tongfa; Han, Hongwei

    2013-01-01

    A mesoscopic methylammonium lead iodide (CH3NH3PbI3) perovskite/TiO2 heterojunction solar cell is developed with low-cost carbon counter electrode (CE) and full printable process. With carbon black/spheroidal graphite CE, this mesoscopic heterojunction solar cell presents high stability and power conversion efficiency of 6.64%, which is higher than that of the flaky graphite based device and comparable to the conventional Au version. PMID:24185501

  18. Synthesis of Ag-doped TiO2 nanoparticles by combining laser decomposition of titanium isopropoxide and ablation of Ag for dye-sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Al-Kamal, Ahmed Kamal

    Nanostructured powders of TiO2 and Ag-doped TiO2 are synthesized by a novel pulsed-laser process that combines laser ablation of a silver (Ag) disc with laser decomposition of a titanium tetra-isopropoxide (TTIP) solution. Nanoparticles are formed by rapid condensation of vaporized species in the plasma plume generated by the high power laser, resulting in the formation of rapidly quenched Ag-doped TiO2 nanoparticles that have far-from-equilibrium or metastable structures. The uniqueness of the new ablation process is that it is a one-step process, in contrast to the two-step process developed by previous researchers in the field. Moreover, its ability to synthesize an extended-solid solution phase of Ag in TiO 2 may also be unique. The present work implies that other oxide phases, such as Al2O3, MgO and MgAl2O4, can be doped with normally insoluble metals, such as Pt and Ir, thus opening new opportunities for catalytic applications. Again, there is the prospect of being able to synthesize nanopowders of diamond, c-BN, and mixtures thereof, which are of interest for applications in machine tools, rock-drill bits, and lightweight armor. A wet-chemistry method is also investigated, which has much in common with that adopted by previous workers in the field. However, photo-voltaic properties do not measure up to expectations based on published data. A possible explanation is that the selected Ag concentrations are too high, so that recombination of holes and electrons occurs via a quantum-tunneling mechanism reduces photo-activity. Future work, therefore, will investigate lower concentrations of Ag dopant in TiO2, while also examining the effects of metastable states, including extended solid solution, amorphous, and semi-crystalline structures.

  19. Growth of Cu2ZnSnS4 Nanocrystallites on TiO2 Nanorod Arrays as Novel Extremely Thin Absorber Solar Cell Structure via the Successive-Ion-Layer-Adsorption-Reaction Method.

    PubMed

    Wang, Zhuoran; Demopoulos, George P

    2015-10-21

    Cu2ZnSnS4 (CZTS) is an environmentally benign semiconductor with excellent optoelectronic properties that attracts a lot of interest in thin film photovoltaics. In departure from that conventional configuration, we fabricate and test a novel absorber-conductor structure featuring in situ successive-ion-layer-adsorption-reaction (SILAR)-deposited CZTS nanocrystallites as a light absorber on one-dimensional TiO2 (rutile) nanorods as an electron conductor. The effectiveness of the nanoscale heterostructure in visible light harvesting and photoelectron generation is demonstrated with an initial short circuit current density of 3.22 mA/cm(2) and an internal quantum efficiency of ∼60% at the blue light region, revealing great potential in developing CZTS extremely thin absorber (ETA) solar cells. PMID:26422062

  20. Efficient solar photocatalytic activity of TiO2 coated nano-porous silicon by atomic layer deposition

    NASA Astrophysics Data System (ADS)

    Sampath, Sridhar; Maydannik, Philipp; Ivanova, Tatiana; Shestakova, Marina; Homola, Tomáš; Bryukvin, Anton; Sillanpää, Mika; Nagumothu, Rameshbabu; Alagan, Viswanathan

    2016-09-01

    In the present study, TiO2 coated nano-porous silicon (TiO2/PS) was prepared by atomic layer deposition (ALD) whereas porous silicon was prepared by stain etching method for efficient solar photocatalytic activity. TiO2/PS was characterized by FESEM, AFM, XRD, XPS and DRS UV-vis spectrophotometer. Absorbance spectrum revealed that TiO2/PS absorbs complete solar light with wave length range of 300 nm-800 nm and most importantly, it absorbs stronger visible light than UV light. The reason for efficient solar light absorption of TiO2/PS is that nanostructured TiO2 layer absorbs UV light and nano-porous silicon layer absorbs visible light which is transparent to TiO2 layer. The amount of visible light absorption of TiO2/PS directly increases with increase of silicon etching time. The effect of silicon etching time of TiO2/PS on solar photocatalytic activity was investigated towards methylene blue dye degradation. Layer by layer solar absorption mechanism was used to explain the enhanced photocatalytic activity of TiO2/PS solar absorber. According to this, the photo-generated electrons of porous silicon will be effectively injected into TiO2 via hetero junction interface which leads to efficient charge separation even though porous silicon is not participating in any redox reactions in direct.

  1. A maskless synthesis of TiO2-nanofiber-based hierarchical structures for solid-state dye-sensitized solar cells with improved performance

    PubMed Central

    2014-01-01

    TiO2 hierarchical nanostructures with secondary growth have been successfully synthesized on electrospun nanofibers via surfactant-free hydrothermal route. The effect of hydrothermal reaction time on the secondary nanostructures has been studied. The synthesized nanostructures comprise electrospun nanofibers which are polycrystalline with anatase phase and have single crystalline, rutile TiO2 nanorod-like structures growing on them. These secondary nanostructures have a preferential growth direction [110]. UV–vis spectroscopy measurements point to better dye loading capability and incident photon to current conversion efficiency spectra show enhanced light harvesting of the synthesized hierarchical structures. Concomitantly, the dye molecules act as spacers between the conduction band electrons of TiO2 and holes in the hole transporting medium, i.e., spiro-OMeTAD and thus enhance open circuit voltage. The charge transport and recombination effects are characterized by electrochemical impedance spectroscopy measurements. As a result of improved light harvesting, dye loading, and reduced recombination losses, the hierarchical nanofibers yield 2.14% electrochemical conversion efficiency which is 50% higher than the efficiency obtained by plain nanofibers. PMID:24410851

  2. DNA mediated wire-like clusters of self-assembled TiO2 nanomaterials: supercapacitor and dye sensitized solar cell applications

    NASA Astrophysics Data System (ADS)

    Nithiyanantham, U.; Ramadoss, Ananthakumar; Ede, Sivasankara Rao; Kundu, Subrata

    2014-06-01

    A new route for the formation of wire-like clusters of TiO2 nanomaterials self-assembled in DNA scaffold within an hour of reaction time is reported. TiO2 nanomaterials are synthesized by the reaction of titanium-isopropoxide with ethanol and water in the presence of DNA under continuous stirring and heating at 60 °C. The individual size of the TiO2 NPs self-assembled in DNA and the diameter of the wires can be tuned by controlling the DNA to Ti-salt molar ratios and other reaction parameters. The eventual diameter of the individual particles varies between 15 +/- 5 nm ranges, whereas the length of the nanowires varies in the 2-3 μm range. The synthesized wire-like DNA-TiO2 nanomaterials are excellent materials for electrochemical supercapacitor and DSSC applications. From the electrochemical supercapacitor experiment, it was found that the TiO2 nanomaterials showed different specific capacitance (Cs) values for the various nanowires, and the order of Cs values are as follows: wire-like clusters (small size) > wire-like clusters (large size). The highest Cs of 2.69 F g-1 was observed for TiO2 having wire-like structure with small sizes. The study of the long term cycling stability of wire-like clusters (small size) electrode were shown to be stable, retaining ca. 80% of the initial specific capacitance, even after 5000 cycles. The potentiality of the DNA-TiO2 nanomaterials was also tested in photo-voltaic applications and the observed efficiency was found higher in the case of wire-like TiO2 nanostructures with larger sizes compared to smaller sizes. In future, the described method can be extended for the synthesis of other oxide based materials on DNA scaffold and can be further used in other applications like sensors, Li-ion battery materials or treatment for environmental waste water.A new route for the formation of wire-like clusters of TiO2 nanomaterials self-assembled in DNA scaffold within an hour of reaction time is reported. TiO2 nanomaterials are synthesized by the reaction of titanium-isopropoxide with ethanol and water in the presence of DNA under continuous stirring and heating at 60 °C. The individual size of the TiO2 NPs self-assembled in DNA and the diameter of the wires can be tuned by controlling the DNA to Ti-salt molar ratios and other reaction parameters. The eventual diameter of the individual particles varies between 15 +/- 5 nm ranges, whereas the length of the nanowires varies in the 2-3 μm range. The synthesized wire-like DNA-TiO2 nanomaterials are excellent materials for electrochemical supercapacitor and DSSC applications. From the electrochemical supercapacitor experiment, it was found that the TiO2 nanomaterials showed different specific capacitance (Cs) values for the various nanowires, and the order of Cs values are as follows: wire-like clusters (small size) > wire-like clusters (large size). The highest Cs of 2.69 F g-1 was observed for TiO2 having wire-like structure with small sizes. The study of the long term cycling stability of wire-like clusters (small size) electrode were shown to be stable, retaining ca. 80% of the initial specific capacitance, even after 5000 cycles. The potentiality of the DNA-TiO2 nanomaterials was also tested in photo-voltaic applications and the observed efficiency was found higher in the case of wire-like TiO2 nanostructures with larger sizes compared to smaller sizes. In future, the described method can be extended for the synthesis of other oxide based materials on DNA scaffold and can be further used in other applications like sensors, Li-ion battery materials or treatment for environmental waste water. Electronic supplementary information (ESI) available: The details about the instrument used for various characterizations and figures related to FE-SEM analysis, EDS analysis, photoluminescence (PL) and LASER Raman study are provided. Table related to FT-IR analysis is also provided. See DOI: 10.1039/c4nr01836b

  3. Photo-electrochemical studies of chemically deposited nanocrystalline meso-porous n-type TiO2 thin films for dye-sensitized solar cell (DSSC) using simple synthesized azo dye

    NASA Astrophysics Data System (ADS)

    Ezema, C. G.; Nwanya, A. C.; Ezema, B. E.; Patil, B. H.; Bulakhe, R. N.; Ukoha, P. O.; Lokhande, C. D.; Maaza, Malik; Ezema, Fabian I.

    2016-04-01

    Nanocrystalline titanium dioxide (TiO2) thin films were deposited by successive ionic layer adsorption and reaction method onto fluorine doped tin oxide coated glass substrate at room temperature (300 K). Titanium trichloride and sodium hydroxide were used as cationic and anionic sources, respectively. The as-deposited and annealed films were characterized for structural, morphological, optical, electrical and wettability properties. The photoelectrochemical study of TiO2 sensitized with a laboratory synthesized organic dye (azo) was evaluated in the polyiodide electrolyte at 40 mW cm-2 light illumination intensity. The photovoltaic characteristics show a fill factor of 0.24 and solar conversion efficiency value of 0.032 % for a TiO2 thickness of 0.96 µm as compared to efficiency of 0.014 % for rose Bengal of the same thickness.

  4. High Efficiency Dye-sensitized Solar Cells Constructed with Composites of TiO2 and the Hot-bubbling Synthesized Ultra-Small SnO2 Nanocrystals

    PubMed Central

    Mao, Xiaoli; Zhou, Ru; Zhang, Shouwei; Ding, Liping; Wan, Lei; Qin, Shengxian; Chen, Zhesheng; Xu, Jinzhang; Miao, Shiding

    2016-01-01

    An efficient photo-anode for the dye-sensitized solar cells (DSSCs) should have features of high loading of dye molecules, favorable band alignments and good efficiency in electron transport. Herein, the 3.4 nm-sized SnO2 nanocrystals (NCs) of high crystallinity, synthesized via the hot-bubbling method, were incorporated with the commercial TiO2 (P25) particles to fabricate the photo-anodes. The optimal percentage of the doped SnO2 NCs was found at ~7.5% (SnO2/TiO2, w/w), and the fabricated DSSC delivers a power conversion efficiency up to 6.7%, which is 1.52 times of the P25 based DSSCs. The ultra-small SnO2 NCs offer three benefits, (1) the incorporation of SnO2 NCs enlarges surface areas of the photo-anode films, and higher dye-loading amounts were achieved; (2) the high charge mobility provided by SnO2 was confirmed to accelerate the electron transport, and the photo-electron recombination was suppressed by the highly-crystallized NCs; (3) the conduction band minimum (CBM) of the SnO2 NCs was uplifted due to the quantum size effects, and this was found to alleviate the decrement in the open-circuit voltage. This work highlights great contributions of the SnO2 NCs to the improvement of the photovoltaic performances in the DSSCs. PMID:26758941

  5. One-step synthesis of vertically aligned anatase thornbush-like TiO2 nanowire arrays on transparent conducting oxides for solid-state dye-sensitized solar cells.

    PubMed

    Roh, Dong Kyu; Chi, Won Seok; Ahn, Sung Hoon; Jeon, Harim; Kim, Jong Hak

    2013-08-01

    Herein, we report a facile synthesis of high-density anatase-phase vertically aligned thornbush-like TiO2 nanowires (TBWs) on transparent conducting oxide glasses. Morphologically controllable TBW arrays of 9 μm in length are generated through a one-step hydrothermal reaction at 200 °C over 11 h using potassium titanium oxide oxalate dehydrate, diethylene glycol (DEG), and water. The TBWs consist of a large number of nanoplates or nanorods, as confirmed by SEM and TEM imaging. The morphologies of TBWs are controllable by adjusting DEG/water ratios. TBW diameters gradually decrease from 600 (TBW600) to 400 (TBW400) to 200 nm (TBW200) and morphologies change from nanoplates to nanorods with an increase in DEG content. TBWs are utilized as photoanodes for quasi-solid-state dye-sensitized solar cells (qssDSSCs) and solid-state DSSCs (ssDSSCs). The energy-conversion efficiency of qssDSSCs is in the order: TBW200 (5.2%)>TBW400 (4.5%)>TBW600 (3.4%). These results can be attributed to the different surface areas, light-scattering effects, and charge transport rates, as confirmed by dye-loading measurements, reflectance spectroscopy, and incident photon-to-electron conversion efficiency and intensity-modulated photovoltage spectroscopy/intensity-modulated photocurrent spectroscopy analyses. TBW200 is further treated with a graft-copolymer-directed organized mesoporous TiO2 to increase the surface area and interconnectivity of TBWs. As a result, the energy-conversion efficiency of the ssDSSC increases to 6.7% at 100 mW cm(-2) , which is among the highest values for N719-dye-based ssDSSCs.

  6. [Performance of solar/S-doped TiO2 on the decomposition of bisphenol A].

    PubMed

    Liu, Cheng; Chen, Wei; Tao, Hui; Lin, Tao

    2009-06-15

    Removal efficiency and influencing factors of bisphenol A by the combined process of solar irradiation and S-doped TiO2 were studied in detail, in which S-doped TiO2 photo-catalyst with high activity was prepared by acid catalyzed hydrolysis method using thiourea as sulfur source. Results showed that bisphenol A could be more effectively oxidized by the solar/S-doped TiO2 process than by solar/TiO2 process, whose removal effect were 79% and 49% after 30 min's irradiation, respectively. Pseudo-first-order model could be used to simulate the oxidation process in which the degradation rate coefficients were independent of the initial concentration of bisphenol A. Degradation rate could be greatly affected by the concentration of H2O2, and the optimum concentration for the system of solar/S-doped TiO2 was found to be 20 mg/L, which was 5 mg/L higher than that of solar/TiO2 system. Lower water pH favored the degradation of bisphenol A, whose degradation rate coefficients at pH 5.5 were about 50% higher than that at pH 8.5. Humic acids decreased both the degradation rate of the two processes, and the influence could be fitted by second-order equation. In addition, solar/S-doped TiO2 process was more easily affected, for the humic acids could not only compete with molecular bisphenol-A for radicals but also adsorb part of visible sunlight which can excite radical with TiO2.

  7. Characterization and improved solar light activity of vanadium doped TiO2/diatomite hybrid catalysts.

    PubMed

    Wang, Bin; Zhang, Guangxin; Leng, Xue; Sun, Zhiming; Zheng, Shuilin

    2015-03-21

    V-doped TiO2/diatomite composite photocatalysts with different vanadium concentrations were synthesized by a modified sol-gel method. The diatomite was responsible for the well dispersion of TiO2 nanoparticles on the matrix and consequently inhibited the agglomeration. V-TiO2/diatomite hybrids showed red shift in TiO2 absorption edge with enhanced absorption intensity. Most importantly, the dopant energy levels were formed in the TiO2 bandgap due to V(4+) ions substituted to Ti(4+) sites. The 0.5% V-TiO2/diatomite photocatalyst displayed narrower bandgap (2.95 eV) compared to undoped sample (3.13 eV) and other doped samples (3.05 eV) with higher doping concentration. The photocatalytic activities of V doped TiO2/diatomite samples for the degradation of Rhodamine B under stimulated solar light illumination were significantly improved compared with the undoped sample. In our case, V(4+) ions incorporated in TiO2 lattice were responsible for increased visible-light absorption and electron transfer to oxygen molecules adsorbed on the surface of TiO2 to produce superoxide radicals ˙O2(-), while V(5+) species presented on the surface of TiO2 particles in the form of V2O5 contributed to e(-)-h(+) separation. In addition, due to the combination of diatomite as support, this hybrid photocatalyst could be separated from solution quickly by natural settlement and exhibited good reusability.

  8. Characterization and improved solar light activity of vanadium doped TiO2/diatomite hybrid catalysts.

    PubMed

    Wang, Bin; Zhang, Guangxin; Leng, Xue; Sun, Zhiming; Zheng, Shuilin

    2015-03-21

    V-doped TiO2/diatomite composite photocatalysts with different vanadium concentrations were synthesized by a modified sol-gel method. The diatomite was responsible for the well dispersion of TiO2 nanoparticles on the matrix and consequently inhibited the agglomeration. V-TiO2/diatomite hybrids showed red shift in TiO2 absorption edge with enhanced absorption intensity. Most importantly, the dopant energy levels were formed in the TiO2 bandgap due to V(4+) ions substituted to Ti(4+) sites. The 0.5% V-TiO2/diatomite photocatalyst displayed narrower bandgap (2.95 eV) compared to undoped sample (3.13 eV) and other doped samples (3.05 eV) with higher doping concentration. The photocatalytic activities of V doped TiO2/diatomite samples for the degradation of Rhodamine B under stimulated solar light illumination were significantly improved compared with the undoped sample. In our case, V(4+) ions incorporated in TiO2 lattice were responsible for increased visible-light absorption and electron transfer to oxygen molecules adsorbed on the surface of TiO2 to produce superoxide radicals ˙O2(-), while V(5+) species presented on the surface of TiO2 particles in the form of V2O5 contributed to e(-)-h(+) separation. In addition, due to the combination of diatomite as support, this hybrid photocatalyst could be separated from solution quickly by natural settlement and exhibited good reusability. PMID:25497036

  9. Near-uv photon efficiency in a TiO2 electrode - Application to hydrogen production from solar energy

    NASA Technical Reports Server (NTRS)

    Desplat, J.-L.

    1976-01-01

    An n-type (001) TiO2 electrode irradiated at 365 nm was tested under anodic polarization. A saturation current independent of pH and proportional to light intensity has been observed. Accurate measurements of the incident power lead to a 60 per cent photon efficiency. A photoelectrochemical cell built with such an electrode, operated under solar irradiation without concentration, produced an electrolysis current of 0.7 mA/sq cm without applied voltage.

  10. Vertical TiO2 Nanorods as a Medium for Stable and High-Efficiency Perovskite Solar Modules.

    PubMed

    Fakharuddin, Azhar; Di Giacomo, Francesco; Palma, Alessandro L; Matteocci, Fabio; Ahmed, Irfan; Razza, Stefano; D'Epifanio, Alessandra; Licoccia, Silvia; Ismail, Jamil; Di Carlo, Aldo; Brown, Thomas M; Jose, Rajan

    2015-08-25

    Perovskite solar cells employing CH3NH3PbI3-xClx active layers show power conversion efficiency (PCE) as high as 20% in single cells and 13% in large area modules. However, their operational stability has often been limited due to degradation of the CH3NH3PbI3-xClx active layer. Here, we report a perovskite solar module (PSM, best and av. PCE 10.5 and 8.1%), employing solution-grown TiO2 nanorods (NRs) as the electron transport layer, which showed an increase in performance (∼5%) even after shelf-life investigation for 2500 h. A crucial issue on the module fabrication was the patterning of the TiO2 NRs, which was solved by interfacial engineering during the growth process and using an optimized laser pulse for patterning. A shelf-life comparison with PSMs built on TiO2 nanoparticles (NPs, best and av. PCE 7.9 and 5.5%) of similar thickness and on a compact TiO2 layer (CL, best and av. PCE 5.8 and 4.9%) shows, in contrast to that observed for NR PSMs, that PCE in NPs and CL PSMs dropped by ∼50 and ∼90%, respectively. This is due to the fact that the CH3NH3PbI3-xClx active layer shows superior phase stability when incorporated in devices with TiO2 NR scaffolds.

  11. Vertical TiO2 Nanorods as a Medium for Stable and High-Efficiency Perovskite Solar Modules.

    PubMed

    Fakharuddin, Azhar; Di Giacomo, Francesco; Palma, Alessandro L; Matteocci, Fabio; Ahmed, Irfan; Razza, Stefano; D'Epifanio, Alessandra; Licoccia, Silvia; Ismail, Jamil; Di Carlo, Aldo; Brown, Thomas M; Jose, Rajan

    2015-08-25

    Perovskite solar cells employing CH3NH3PbI3-xClx active layers show power conversion efficiency (PCE) as high as 20% in single cells and 13% in large area modules. However, their operational stability has often been limited due to degradation of the CH3NH3PbI3-xClx active layer. Here, we report a perovskite solar module (PSM, best and av. PCE 10.5 and 8.1%), employing solution-grown TiO2 nanorods (NRs) as the electron transport layer, which showed an increase in performance (∼5%) even after shelf-life investigation for 2500 h. A crucial issue on the module fabrication was the patterning of the TiO2 NRs, which was solved by interfacial engineering during the growth process and using an optimized laser pulse for patterning. A shelf-life comparison with PSMs built on TiO2 nanoparticles (NPs, best and av. PCE 7.9 and 5.5%) of similar thickness and on a compact TiO2 layer (CL, best and av. PCE 5.8 and 4.9%) shows, in contrast to that observed for NR PSMs, that PCE in NPs and CL PSMs dropped by ∼50 and ∼90%, respectively. This is due to the fact that the CH3NH3PbI3-xClx active layer shows superior phase stability when incorporated in devices with TiO2 NR scaffolds. PMID:26208221

  12. WO3/TiO2 nanotube photoanodes for solar water splitting with simultaneous wastewater treatment.

    SciTech Connect

    Reyes, Karla Rosa; Robinson, David B.

    2013-05-01

    Nanostructured WO3/TiO2 nanotubes with properties that enhance solar photoconversion reactions were developed, characterized and tested. The TiO2 nanotubes were prepared by anodization of Ti foil, and WO3 was electrodeposited on top of the nanotubes. SEM images show that these materials have the same ordered structure as TiO2 nanotubes, with an external nanostructured WO3 layer. Diffuse reflectance spectra showed an increase in the visible absorption relative to bare TiO2 nanotubes, and in the UV absorption relative to bare WO3 films. Incident simulated solar photon-to-current efficiency increased from 30% (for bare WO3) to 50% (for WO3/TiO2 composites). With the addition of diverse organic pollutants, the photocurrent densities exhibited more than a 5-fold increase. Chemical oxygen demand measurements showed the simultaneous photodegradation of organic pollutants. The results of this work indicate that the unique structure and composition of these composite materials enhance the charge carrier transport and optical properties compared with the parent materials.

  13. Array of solid-state dye-sensitized solar cells with micropatterned TiO2 nanoparticles for a high-voltage power source.

    PubMed

    Cho, Seong-Min; Park, Hea-Lim; Kim, Min-Hoi; Kim, Se-Um; Lee, Sin-Doo

    2013-11-20

    We demonstrate an array of solid-state dye-sensitized solar cells (SS-DSSCs) for a high-voltage power source based on micropatterned titanium dioxide nanoparticles (TNPs) as photoanodes connected in series. The underlying concept of patterning the TNP of a few micrometers thick lies on the combination of the lift-off process of transfer-printed patterns of a sacrificial layer and the soft-cure treatment of the TNP for fixation. This sacrificial layer approach allows for high pattern fidelity and stability, and it enables to construct stable, micrometer-thick, and contamination-free TNP patterns for developing the SS-DSSC array for miniature high-voltage applications. The array of 20 SS-DSSCs integrated in series is found to show a voltage output of around 7 V.

  14. Growth of aligned single-crystalline rutile TiO2 nanowires on arbitrary substrates and their application in dye-sensitized solar cells

    SciTech Connect

    Kumar, Akshay; Madaria, Anuj R.; Zhou, Chongwu

    2010-05-06

    TiO{sub 2} is a wide band gap semiconductor with important applications in photovoltaic cells and photocatalysis. In this paper, we report synthesis of single-crystalline rutile phase TiO{sub 2} nanowires on arbitrary substrates, including fluorine-doped tin oxide (FTO), glass slides, tin-doped indium oxide (ITO), Si/SiO{sub 2}, Si(100), Si(111), and glass rods. By controlling the growth parameters such as growth temperature, precursor concentrations, and so forth, we demonstrate that anisotropic growth of TiO{sub 2} is possible leading to various morphologies of nanowires. Optimization of the growth recipe leads to well-aligned vertical array of TiO{sub 2} nanowires on both FTO and glass substrates. Effects of various titanium precursors on the growth kinetics, especially on the growth rate of nanowires, are also studied. Finally, application of vertical array of TiO{sub 2} nanowires on FTO as the photoanode is demonstrated in dye-sensitized solar cell with an efficiency of 2.9 ± 0.2%.

  15. A Novel Method for the Preparation of CdS Quantum Dots Sensitized Solar Cells Based on Free-Standing and Through-Hole TiO2 Nanotube Arrays.

    PubMed

    Wang, Yang; Li, Zhen; Li, Fei; Tian, Yunfeng; Zhao, Wen; Liu, Xueqin; Yang, Jianbo

    2016-06-01

    The crystallized free-standing through-hole TiO2 nanotube arrays (TNAs) membranes were fabricated by a facile method. CdS quantum dots (QDs) are assembled onto free-standing through-hole NTAs films using successive ionic layer adsorption and reaction (SILAR) process. The CdS/TNAs were easily transferred to the fluorine-doped tin oxide glass to form photoanodes after they were sensitized by modifying the traditional procedure. The morphology and crystalline phase of the TiO2 nanotubes were studied by field emission scanning electron microscopy (FESEM) and X-ray diffraction (XRD). The cells with 5 SILAR cycles show photovoltaic conversion efficiency as high as 3.34% under simulated sunlight (AM 1.5, 100 mW x cm(-2)). Obviously, the new approach promotes the uniform distribution of CdS on the densely aligned TNAs and prevents the clogging of CdS quantum dots (QDs) at the TiO2 nanotube mouth. Such enhanced properties may be ascribed to the strong combination between CdS and TiO2, favorable for charge separation of TNAs. PMID:27427675

  16. Size-tunable TiO2 nanorod microspheres synthesised via a one-pot solvothermal method and used as the scattering layer for dye-sensitized solar cells.

    PubMed

    Rui, Yichuan; Li, Yaogang; Zhang, Qinghong; Wang, Hongzhi

    2013-12-21

    TiO2 microspheres assembled by single crystalline rutile TiO2 nanorods were synthesized by one-pot solvothermal treatment at 180 °C based on an aqueous-organic mixture solution containing n-hexane, distilled water, titanium n-butoxide and hydrochloric acid. The spheres had a radiative structure from the center, and their diameters were controlled in the range from 1 to 5 μm by adjusting the volume of the reactant water. Nitrogen adsorption-desorption isotherms showed that all the as-prepared microspheres had relatively high specific surface areas of about 50 m(2) g(-1). The 1 μm sized TiO2 nanorod microspheres were fabricated as a scattering overlayer in DSSCs, leading to a remarkable improvement in the power conversion efficiency: 8.22% of the bi-layer DSSCs versus 7.00% for the reference cell made of a single-layer film prepared from nanocrystalline TiO2. Such improvement was mainly attributed to the enhanced light harvesting and dye loading brought by the effective scattering centers.

  17. Size-tunable TiO2 nanorod microspheres synthesised via a one-pot solvothermal method and used as the scattering layer for dye-sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Rui, Yichuan; Li, Yaogang; Zhang, Qinghong; Wang, Hongzhi

    2013-11-01

    TiO2 microspheres assembled by single crystalline rutile TiO2 nanorods were synthesized by one-pot solvothermal treatment at 180 °C based on an aqueous-organic mixture solution containing n-hexane, distilled water, titanium n-butoxide and hydrochloric acid. The spheres had a radiative structure from the center, and their diameters were controlled in the range from 1 to 5 μm by adjusting the volume of the reactant water. Nitrogen adsorption-desorption isotherms showed that all the as-prepared microspheres had relatively high specific surface areas of about 50 m2 g-1. The 1 μm sized TiO2 nanorod microspheres were fabricated as a scattering overlayer in DSSCs, leading to a remarkable improvement in the power conversion efficiency: 8.22% of the bi-layer DSSCs versus 7.00% for the reference cell made of a single-layer film prepared from nanocrystalline TiO2. Such improvement was mainly attributed to the enhanced light harvesting and dye loading brought by the effective scattering centers.TiO2 microspheres assembled by single crystalline rutile TiO2 nanorods were synthesized by one-pot solvothermal treatment at 180 °C based on an aqueous-organic mixture solution containing n-hexane, distilled water, titanium n-butoxide and hydrochloric acid. The spheres had a radiative structure from the center, and their diameters were controlled in the range from 1 to 5 μm by adjusting the volume of the reactant water. Nitrogen adsorption-desorption isotherms showed that all the as-prepared microspheres had relatively high specific surface areas of about 50 m2 g-1. The 1 μm sized TiO2 nanorod microspheres were fabricated as a scattering overlayer in DSSCs, leading to a remarkable improvement in the power conversion efficiency: 8.22% of the bi-layer DSSCs versus 7.00% for the reference cell made of a single-layer film prepared from nanocrystalline TiO2. Such improvement was mainly attributed to the enhanced light harvesting and dye loading brought by the effective scattering

  18. A Multiscale TiO2 Nanorod Array for Ultrasensitive Capture of Circulating Tumor Cells.

    PubMed

    Sun, Na; Li, Xinpan; Wang, Zhili; Zhang, Ruihua; Wang, Jine; Wang, Kewei; Pei, Renjun

    2016-05-25

    In this work, a uniform multiscale TiO2 nanorod array is fabricated to provide a "multi-scale interacting platform" for cell capture, which exhibits excellent capture specificity and sensitivity of the target cells after modification with bovine serum albumin (BSA) and DNA aptamer. After studying the capture performance of the BSA-aptamer TiO2 nanorod substrates and other nanostructured substrates, we can conclude that the multisacle TiO2 nanorod substrates could indeed effectively enhance the capture yields of target cancer cells. The capture yield of artificial blood samples on the BSA-aptamer TiO2 nanorod substrates is up to 85%-95%, revealing the potential application of the TiO2 nanorods on efficient and sensitive capture of rare circulating tumor cells. PMID:27176724

  19. CdS sensitized 3D hierarchical TiO2/ZnO heterostructure for efficient solar energy conversion

    NASA Astrophysics Data System (ADS)

    Zheng, Zhaoke; Xie, Wen; Lim, Zhi Shiuh; You, Lu; Wang, Junling

    2014-07-01

    For conventional dye or quantum dot sensitized solar cells, which are fabricated using mesoporous films, the inefficient electron transport due to defects such as grain boundaries and surface traps is a major drawback. To simultaneously increase the carrier transport efficiency as well as the surface area, optimal-assembling of hierarchical nanostructures is an attractive approach. Here, a three dimensional (3D) hierarchical heterostructure, consisting of CdS sensitized one dimensional (1D) ZnO nanorods deposited on two dimensional (2D) TiO2 (001) nanosheet, is prepared via a solution-process method. Such heterstructure exhibits significantly enhanced photoelectric and photocatalytic H2 evolution performance compared with CdS sensitized 1D ZnO nanorods/1D TiO2 nanorods photoanode, as a result of the more efficient light harvesting over the entire visible light spectrum and the effective electron transport through a highly connected 3D network.

  20. CdS sensitized 3D hierarchical TiO2/ZnO heterostructure for efficient solar energy conversion

    PubMed Central

    Zheng, Zhaoke; Xie, Wen; Lim, Zhi Shiuh; You, Lu; Wang, Junling

    2014-01-01

    For conventional dye or quantum dot sensitized solar cells, which are fabricated using mesoporous films, the inefficient electron transport due to defects such as grain boundaries and surface traps is a major drawback. To simultaneously increase the carrier transport efficiency as well as the surface area, optimal-assembling of hierarchical nanostructures is an attractive approach. Here, a three dimensional (3D) hierarchical heterostructure, consisting of CdS sensitized one dimensional (1D) ZnO nanorods deposited on two dimensional (2D) TiO2 (001) nanosheet, is prepared via a solution-process method. Such heterstructure exhibits significantly enhanced photoelectric and photocatalytic H2 evolution performance compared with CdS sensitized 1D ZnO nanorods/1D TiO2 nanorods photoanode, as a result of the more efficient light harvesting over the entire visible light spectrum and the effective electron transport through a highly connected 3D network. PMID:25030846

  1. Increased biodegradability of Ultracid in aqueous solutions with solar TiO2 photocatalysis.

    PubMed

    García-Ripoll, A; Amat, A M; Arques, A; Vicente, R; López, M F; Oller, I; Maldonado, M I; Gernjak, W

    2007-06-01

    A study of solar TiO(2) photocatalytic degradation of the insecticide Ultracidtrade mark, a commercial formulation containing methidathion as the active ingredient, is described. Total elimination of methidathion can be achieved in less than 2h of irradiation, although longer solar exposures are needed for complete mineralisation of the solution (7-8h). Activated sludge respirometry shows that when methidathion is eliminated, the solution is detoxified, so further irradiation does not seem necessary. A Zahn-Wellens test also indicates improved biodegradability of the treated sample after abatement of the active ingredient. Finally, analysis of the ions formed indicates that the thiophosphate moiety of the molecule is preferentially attacked in the early stages of the reaction, while the thiadiazole ring is more sluggish to the effect of TiO(2)-photocatalysis.

  2. A facile method to prepare SnO2 nanotubes for use in efficient SnO2-TiO2 core-shell dye-sensitized solar cells.

    PubMed

    Gao, Caitian; Li, Xiaodong; Lu, Bingan; Chen, Lulu; Wang, Youqing; Teng, Feng; Wang, Jiangtao; Zhang, Zhenxing; Pan, Xiaojun; Xie, Erqing

    2012-06-01

    A high-efficiency photoelectrode for dye-sensitized solar cells (DSSCs) should combine the advantageous features of fast electron transport, slow interfacial electron recombination and large specific surface area. However, these three requirements usually cannot be achieved simultaneously in the present state-of-the-art research. Here we report a simple procedure to combine the three conflicting requirements by using porous SnO(2) nanotube-TiO(2) (SnO(2) NT-TiO(2)) core-shell structured photoanodes for DSSCs. The SnO(2) nanotubes are prepared by electrospinning of polyvinyl pyrrolidone (PVP)/tin dichloride dihydrate (SnCl(2)·2H(2)O) solution followed by direct sintering of the as-spun nanofibers. A possible evolution mechanism is proposed. The power conversion efficiency (PCE) value of the SnO(2) NT-TiO(2) core-shell structured DSSCs (∼5.11%) is above five times higher than that of SnO(2) nanotube (SnO(2) NT) DSSCs (∼0.99%). This PCE value is also higher than that of TiO(2) nanoparticles (P25) DSSCs (∼4.82%), even though the amount of dye molecules adsorbed to the SnO(2) NT-TiO(2) photoanode is less than half of that in the P25 film. This simple procedure provides a new approach to achieve the three conflicting requirements simultaneously, which has been demonstrated as a promising strategy to obtain high-efficiency DSSCs. PMID:22572999

  3. Enhanced performance of CH3NH3PbI3- x Cl x perovskite solar cells by CH3NH3I modification of TiO2-perovskite layer interface

    NASA Astrophysics Data System (ADS)

    Wang, Wen; Zhang, Zongbao; Cai, Yangyang; Chen, Jinshan; Wang, Jianming; Huang, Riyan; Lu, Xubing; Gao, Xingsen; Shui, Lingling; Wu, Sujuan; Liu, Jun-Ming

    2016-06-01

    In this work, perovskite solar cells (PSCs) with CH3NH3PbI3- x Cl x as active layer and spiro-OMeTAD as hole-transport media have been fabricated by one-step method. The methylammonium iodide (CH3NH3I) solution with different concentrations is used to modify the interface between mesoporous TiO2 (meso-TiO2) film and CH3NH3PbI3- x Cl x perovskite layer. Several techniques including X-ray diffraction, scanning electron microscopy, optical absorption, electrochemical impedance spectroscopy (EIS) and photoluminescence are used to investigate the effect of the interfacial modification. It is found that the interfacial modification by CH3NH3I enhance the crystallinity and increase the grain size of CH3NH3PbI3- x Cl x layer, and improve the surface wetting properties of perovskite precursor on meso-TiO2 film. The sunlight absorption and external quantum efficiency of PSCs in the visible region with wavelength less than 600 nm have been improved. The Nyquist plots obtained from the EIS suggest that the CH3NH3I modification can reduce the charge recombination rates. The photoluminescence measurement shows that the exciton dissociation in the modified devices is more effective than that in the control samples. The photovoltaic performance of the modified devices can be significantly improved with respect to the reference (control) devices. The CH3NH3I modified devices at the optimized concentration demonstrate the average power conversion efficiency of 12.27 % in comparison with the average efficiency of 9.68 % for the reference devices.

  4. Enhanced performance of CH3NH3PbI3-x Cl x perovskite solar cells by CH3NH3I modification of TiO2-perovskite layer interface.

    PubMed

    Wang, Wen; Zhang, Zongbao; Cai, Yangyang; Chen, Jinshan; Wang, Jianming; Huang, Riyan; Lu, Xubing; Gao, Xingsen; Shui, Lingling; Wu, Sujuan; Liu, Jun-Ming

    2016-12-01

    In this work, perovskite solar cells (PSCs) with CH3NH3PbI3-x Cl x as active layer and spiro-OMeTAD as hole-transport media have been fabricated by one-step method. The methylammonium iodide (CH3NH3I) solution with different concentrations is used to modify the interface between mesoporous TiO2 (meso-TiO2) film and CH3NH3PbI3-x Cl x perovskite layer. Several techniques including X-ray diffraction, scanning electron microscopy, optical absorption, electrochemical impedance spectroscopy (EIS) and photoluminescence are used to investigate the effect of the interfacial modification. It is found that the interfacial modification by CH3NH3I enhance the crystallinity and increase the grain size of CH3NH3PbI3-x Cl x layer, and improve the surface wetting properties of perovskite precursor on meso-TiO2 film. The sunlight absorption and external quantum efficiency of PSCs in the visible region with wavelength less than 600 nm have been improved. The Nyquist plots obtained from the EIS suggest that the CH3NH3I modification can reduce the charge recombination rates. The photoluminescence measurement shows that the exciton dissociation in the modified devices is more effective than that in the control samples. The photovoltaic performance of the modified devices can be significantly improved with respect to the reference (control) devices. The CH3NH3I modified devices at the optimized concentration demonstrate the average power conversion efficiency of 12.27 % in comparison with the average efficiency of 9.68 % for the reference devices.

  5. Solar-light photocatalytic disinfection using crystalline/amorphous low energy bandgap reduced TiO2

    NASA Astrophysics Data System (ADS)

    Kim, Youngmin; Hwang, Hee Min; Wang, Luyang; Kim, Ikjoon; Yoon, Yeoheung; Lee, Hyoyoung

    2016-04-01

    A generation of reactive oxygen species (ROS) from TiO2 under solar light has been long sought since the ROS can disinfect organic pollutants. We found that newly developed crystalline/amorphous reduced TiO2 (rTiO2) that has low energy bandgap can effectively generate ROS under solar light and successfully remove a bloom of algae. The preparation of rTiO2 is a one-pot and mass productive solution-process reduction using lithium-ethylene diamine (Li-EDA) at room temperature. Interestingly only the rutile phase of TiO2 crystal was reduced, while the anatase phase even in case of both anatase/rutile phased TiO2 was not reduced. Only reduced TiO2 materials can generate ROS under solar light, which was confirmed by electron spin resonance. Among the three different types of Li-EDA treated TiO2 (anatase, rutile and both phased TiO2), the both phased rTiO2 showed the best performance to produce ROS. The generated ROS effectively removed the common green algae Chlamydomonas. This is the first report on algae degradation under solar light, proving the feasibility of commercially available products for disinfection.

  6. Solar-light photocatalytic disinfection using crystalline/amorphous low energy bandgap reduced TiO2

    PubMed Central

    Kim, Youngmin; Hwang, Hee Min; Wang, Luyang; Kim, Ikjoon; Yoon, Yeoheung; Lee, Hyoyoung

    2016-01-01

    A generation of reactive oxygen species (ROS) from TiO2 under solar light has been long sought since the ROS can disinfect organic pollutants. We found that newly developed crystalline/amorphous reduced TiO2 (rTiO2) that has low energy bandgap can effectively generate ROS under solar light and successfully remove a bloom of algae. The preparation of rTiO2 is a one-pot and mass productive solution-process reduction using lithium-ethylene diamine (Li-EDA) at room temperature. Interestingly only the rutile phase of TiO2 crystal was reduced, while the anatase phase even in case of both anatase/rutile phased TiO2 was not reduced. Only reduced TiO2 materials can generate ROS under solar light, which was confirmed by electron spin resonance. Among the three different types of Li-EDA treated TiO2 (anatase, rutile and both phased TiO2), the both phased rTiO2 showed the best performance to produce ROS. The generated ROS effectively removed the common green algae Chlamydomonas. This is the first report on algae degradation under solar light, proving the feasibility of commercially available products for disinfection. PMID:27121120

  7. Solar-light photocatalytic disinfection using crystalline/amorphous low energy bandgap reduced TiO2.

    PubMed

    Kim, Youngmin; Hwang, Hee Min; Wang, Luyang; Kim, Ikjoon; Yoon, Yeoheung; Lee, Hyoyoung

    2016-04-28

    A generation of reactive oxygen species (ROS) from TiO2 under solar light has been long sought since the ROS can disinfect organic pollutants. We found that newly developed crystalline/amorphous reduced TiO2 (rTiO2) that has low energy bandgap can effectively generate ROS under solar light and successfully remove a bloom of algae. The preparation of rTiO2 is a one-pot and mass productive solution-process reduction using lithium-ethylene diamine (Li-EDA) at room temperature. Interestingly only the rutile phase of TiO2 crystal was reduced, while the anatase phase even in case of both anatase/rutile phased TiO2 was not reduced. Only reduced TiO2 materials can generate ROS under solar light, which was confirmed by electron spin resonance. Among the three different types of Li-EDA treated TiO2 (anatase, rutile and both phased TiO2), the both phased rTiO2 showed the best performance to produce ROS. The generated ROS effectively removed the common green algae Chlamydomonas. This is the first report on algae degradation under solar light, proving the feasibility of commercially available products for disinfection.

  8. Solar-light photocatalytic disinfection using crystalline/amorphous low energy bandgap reduced TiO2.

    PubMed

    Kim, Youngmin; Hwang, Hee Min; Wang, Luyang; Kim, Ikjoon; Yoon, Yeoheung; Lee, Hyoyoung

    2016-01-01

    A generation of reactive oxygen species (ROS) from TiO2 under solar light has been long sought since the ROS can disinfect organic pollutants. We found that newly developed crystalline/amorphous reduced TiO2 (rTiO2) that has low energy bandgap can effectively generate ROS under solar light and successfully remove a bloom of algae. The preparation of rTiO2 is a one-pot and mass productive solution-process reduction using lithium-ethylene diamine (Li-EDA) at room temperature. Interestingly only the rutile phase of TiO2 crystal was reduced, while the anatase phase even in case of both anatase/rutile phased TiO2 was not reduced. Only reduced TiO2 materials can generate ROS under solar light, which was confirmed by electron spin resonance. Among the three different types of Li-EDA treated TiO2 (anatase, rutile and both phased TiO2), the both phased rTiO2 showed the best performance to produce ROS. The generated ROS effectively removed the common green algae Chlamydomonas. This is the first report on algae degradation under solar light, proving the feasibility of commercially available products for disinfection. PMID:27121120

  9. Advanced nanoporous TiO2 photocatalysts by hydrogen plasma for efficient solar-light photocatalytic application.

    PubMed

    An, Ha-Rim; Park, So Young; Kim, Hyeran; Lee, Che Yoon; Choi, Saehae; Lee, Soon Chang; Seo, Soonjoo; Park, Edmond Changkyun; Oh, You-Kwan; Song, Chan-Geun; Won, Jonghan; Kim, Youn Jung; Lee, Jouhahn; Lee, Hyun Uk; Lee, Young-Chul

    2016-01-01

    We report an effect involving hydrogen (H2)-plasma-treated nanoporous TiO2(H-TiO2) photocatalysts that improve photocatalytic performance under solar-light illumination. H-TiO2 photocatalysts were prepared by application of hydrogen plasma of assynthesized TiO2(a-TiO2) without annealing process. Compared with the a-TiO2, the H-TiO2 exhibited high anatase/brookite bicrystallinity and a porous structure. Our study demonstrated that H2 plasma is a simple strategy to fabricate H-TiO2 covering a large surface area that offers many active sites for the extension of the adsorption spectra from ultraviolet (UV) to visible range. Notably, the H-TiO2 showed strong ·OH free-radical generation on the TiO2 surface under both UV- and visible-light irradiation with a large responsive surface area, which enhanced photocatalytic efficiency. Under solar-light irradiation, the optimized H-TiO2 120(H2-plasma treatment time: 120 min) photocatalysts showed unprecedentedly excellent removal capability for phenol (Ph), reactive black 5(RB 5), rhodamine B (Rho B) and methylene blue (MB) - approximately four-times higher than those of the other photocatalysts (a-TiO2 and P25) - resulting in complete purification of the water. Such well-purified water (>90%) can utilize culturing of cervical cancer cells (HeLa), breast cancer cells (MCF-7), and keratinocyte cells (HaCaT) while showing minimal cytotoxicity. Significantly, H-TiO2 photocatalysts can be mass-produced and easily processed at room temperature. We believe this novel method can find important environmental and biomedical applications. PMID:27406992

  10. Advanced nanoporous TiO2 photocatalysts by hydrogen plasma for efficient solar-light photocatalytic application

    PubMed Central

    An, Ha-Rim; Park, So Young; Kim, Hyeran; Lee, Che Yoon; Choi, Saehae; Lee, Soon Chang; Seo, Soonjoo; Park, Edmond Changkyun; Oh, You-Kwan; Song, Chan-Geun; Won, Jonghan; Kim, Youn Jung; Lee, Jouhahn; Lee, Hyun Uk; Lee, Young-Chul

    2016-01-01

    We report an effect involving hydrogen (H2)-plasma-treated nanoporous TiO2(H-TiO2) photocatalysts that improve photocatalytic performance under solar-light illumination. H-TiO2 photocatalysts were prepared by application of hydrogen plasma of assynthesized TiO2(a-TiO2) without annealing process. Compared with the a-TiO2, the H-TiO2 exhibited high anatase/brookite bicrystallinity and a porous structure. Our study demonstrated that H2 plasma is a simple strategy to fabricate H-TiO2 covering a large surface area that offers many active sites for the extension of the adsorption spectra from ultraviolet (UV) to visible range. Notably, the H-TiO2 showed strong ·OH free-radical generation on the TiO2 surface under both UV- and visible-light irradiation with a large responsive surface area, which enhanced photocatalytic efficiency. Under solar-light irradiation, the optimized H-TiO2 120(H2-plasma treatment time: 120 min) photocatalysts showed unprecedentedly excellent removal capability for phenol (Ph), reactive black 5(RB 5), rhodamine B (Rho B) and methylene blue (MB) — approximately four-times higher than those of the other photocatalysts (a-TiO2 and P25) — resulting in complete purification of the water. Such well-purified water (>90%) can utilize culturing of cervical cancer cells (HeLa), breast cancer cells (MCF-7), and keratinocyte cells (HaCaT) while showing minimal cytotoxicity. Significantly, H-TiO2 photocatalysts can be mass-produced and easily processed at room temperature. We believe this novel method can find important environmental and biomedical applications. PMID:27406992

  11. Advanced nanoporous TiO2 photocatalysts by hydrogen plasma for efficient solar-light photocatalytic application

    NASA Astrophysics Data System (ADS)

    An, Ha-Rim; Park, So Young; Kim, Hyeran; Lee, Che Yoon; Choi, Saehae; Lee, Soon Chang; Seo, Soonjoo; Park, Edmond Changkyun; Oh, You-Kwan; Song, Chan-Geun; Won, Jonghan; Kim, Youn Jung; Lee, Jouhahn; Lee, Hyun Uk; Lee, Young-Chul

    2016-07-01

    We report an effect involving hydrogen (H2)-plasma-treated nanoporous TiO2(H-TiO2) photocatalysts that improve photocatalytic performance under solar-light illumination. H-TiO2 photocatalysts were prepared by application of hydrogen plasma of assynthesized TiO2(a-TiO2) without annealing process. Compared with the a-TiO2, the H-TiO2 exhibited high anatase/brookite bicrystallinity and a porous structure. Our study demonstrated that H2 plasma is a simple strategy to fabricate H-TiO2 covering a large surface area that offers many active sites for the extension of the adsorption spectra from ultraviolet (UV) to visible range. Notably, the H-TiO2 showed strong ·OH free-radical generation on the TiO2 surface under both UV- and visible-light irradiation with a large responsive surface area, which enhanced photocatalytic efficiency. Under solar-light irradiation, the optimized H-TiO2 120(H2-plasma treatment time: 120 min) photocatalysts showed unprecedentedly excellent removal capability for phenol (Ph), reactive black 5(RB 5), rhodamine B (Rho B) and methylene blue (MB) — approximately four-times higher than those of the other photocatalysts (a-TiO2 and P25) — resulting in complete purification of the water. Such well-purified water (>90%) can utilize culturing of cervical cancer cells (HeLa), breast cancer cells (MCF-7), and keratinocyte cells (HaCaT) while showing minimal cytotoxicity. Significantly, H-TiO2 photocatalysts can be mass-produced and easily processed at room temperature. We believe this novel method can find important environmental and biomedical applications.

  12. Exposure to TiO2 nanoparticles increases Staphylococcusaureusinfection of HeLa cells

    NASA Astrophysics Data System (ADS)

    Xu, Yan; Wei, Ming-Tzo; Walker, Stephen. G.; Wang, Hong Zhan; Gondon, Chris; Brink, Peter; Guterman, Shoshana; Zawacki, Emma; Applebaum, Eliana; Rafailovich, Miriam; Ou-Yang, H. Daniel; Mironava, Tatsiana

    TiO2 is one of the most common nanoparticles in industry from food additives to energy generation. Even though TiO2 is also used as an anti-bacterial agent in combination with UV, we found that, in the absence of UV, exposure of HeLa cells to TiO2 nanoparticles largely increased their risk of bacterial invasion. HeLa cells cultured with low dosage rutile and anatase TiO2 nanoparticles (0.1 mg/ml) for 24 hrs prior to exposure to bacteria had 350% and 250% respectively more bacteria infected per cell. The increase was attributed to increased LDH leakage, and changes in the mechanical response of the cell membrane. On the other hand, macrophages exposed to TiO2 particles ingested 40% fewer bacteria, further increasing the risk of infection. In combination, these two factors raise serious concerns regarding the impact of exposure to TiO2 nanoparticles on the ability of organisms to resist bacterial infection.

  13. Superior Antibacterial Activity of Fe3O4-TiO2 Nanosheets under Solar Light.

    PubMed

    Ma, Shuanglong; Zhan, Sihui; Jia, Yanan; Zhou, Qixing

    2015-10-01

    Fe3O4-TiO2 nanosheets (Fe3O4-TNS) were synthesized by means of lamellar reverse micelles and solvothermal method, which were characterized by TEM, XRD, XPS, BET, and magnetic property analysis. It can be found that Fe3O4-TNS nanosheets exhibited better photocatalytic antibacterial activity toward Gram-negative Escherichia coli and Gram-positive Staphylococcus aureus than pure Fe3O4 and TNS, and the antibacterial efficiency could reach 87.2% and 93.7% toward E. coli and S. aureus with 100 μg/mL Fe3O4-TNS after 2 h of simulated solar light illumination, respectively. The photocatalytic destruction of bacteria was further confirmed by fluorescent-based cell live/dead test and SEM images. It was uncovered that Fe3O4-TNS inactivated G- E. coli and G+ S. aureus by different mechanisms: the destruction of outer membranes and ruptured cell bodies were responsible for the bactericidal effect against E. coli, while the antibacterial effect toward S. aureus were due to the fact that the cells were adsorbed in form of clusters by massive Fe3O4-TNS, which could restrict their activities and cause malfunction of the selective permeable barriers. Furthermore, the antibacterial mechanism was studied by employing scavengers to understand exact roles of different reactive species, indicating the key roles of h(+) and H2O2. The recovery and reusability experiments indicated that Fe3O4-TNS still retained more than 90% bacteria removal efficiency even after five cycles. Considering the easy magnetic separation, bulk availability, and high antibacterial activity of Fe3O4-TNS, it is a promising candidate for cleaning the microbial contaminated water environment.

  14. Superior Antibacterial Activity of Fe3O4-TiO2 Nanosheets under Solar Light.

    PubMed

    Ma, Shuanglong; Zhan, Sihui; Jia, Yanan; Zhou, Qixing

    2015-10-01

    Fe3O4-TiO2 nanosheets (Fe3O4-TNS) were synthesized by means of lamellar reverse micelles and solvothermal method, which were characterized by TEM, XRD, XPS, BET, and magnetic property analysis. It can be found that Fe3O4-TNS nanosheets exhibited better photocatalytic antibacterial activity toward Gram-negative Escherichia coli and Gram-positive Staphylococcus aureus than pure Fe3O4 and TNS, and the antibacterial efficiency could reach 87.2% and 93.7% toward E. coli and S. aureus with 100 μg/mL Fe3O4-TNS after 2 h of simulated solar light illumination, respectively. The photocatalytic destruction of bacteria was further confirmed by fluorescent-based cell live/dead test and SEM images. It was uncovered that Fe3O4-TNS inactivated G- E. coli and G+ S. aureus by different mechanisms: the destruction of outer membranes and ruptured cell bodies were responsible for the bactericidal effect against E. coli, while the antibacterial effect toward S. aureus were due to the fact that the cells were adsorbed in form of clusters by massive Fe3O4-TNS, which could restrict their activities and cause malfunction of the selective permeable barriers. Furthermore, the antibacterial mechanism was studied by employing scavengers to understand exact roles of different reactive species, indicating the key roles of h(+) and H2O2. The recovery and reusability experiments indicated that Fe3O4-TNS still retained more than 90% bacteria removal efficiency even after five cycles. Considering the easy magnetic separation, bulk availability, and high antibacterial activity of Fe3O4-TNS, it is a promising candidate for cleaning the microbial contaminated water environment. PMID:26372171

  15. Fe vs. TiO2 Photo-assisted Processes for Enhancing the Solar Inactivation of Bacteria in Water.

    PubMed

    Pulgarin, César

    2015-01-01

    Batch solar water disinfection (SODIS) is a known, simple and low-cost water treatment technology. SODIS is based on the synergistic action of temperature increase and light-assisted generation of Reactive Oxygen Species (ROS) on bacteria. ROS are generated via the action of solar photons on i) Natural Organic Matter (NOM), ii) some mineral components of water (Fe oxides or Fe-organic complexes, nitrogen compounds) and iii) endogenous bacteria photosensitizers (e.g. cytochrome). SODIS has proven its effectiveness for remote settlements or urban slums in regions with high incident solar radiation. All of the internal and external simultaneous processes are often driven by photoactive Fe-species present in the cell, as well as in the natural water sources. In SODIS, a temperature of 50 °C is required and due to this temperature dependence, only 1-2 L can be treated at a time. As required exposure time strongly depends on irradiation intensity and temperature, some SODIS households could be overburdened, leading to inadequate treatment and probable bacterial re-growth. This is why TiO(2) photocatalysis and Fe photo-assisted systems (i.e. photo-Fenton reactants) have been considered to enhance the photo-catalytic processes already present in natural water sources when exposed to solar light. Both TiO(2) and Fe-photoassisted processes, when applied to water disinfection aim to improve the performance of solar bacteria inactivation systems by i) enhancing ROS production, ii) making the process independent from the rise in temperature and as a consequence iii) allowing the treatment of larger volumes than 1-2 L of water and iv) prevent bacterial (re)growth, sometimes observed after sole solar treatment. PMID:26507082

  16. Optimum Thickness Conditions of TiO2 Nanotubes Layer for Efficient Electrochemical Luminescence Cells Application.

    PubMed

    Choi, Min-Ki; Sung, Youl-Moon; Park, Min-Woo

    2015-02-01

    We report a TiO2 nanotubes (NTs)-based Electrochemical luminescence (ECL) cell. The ECL cell was fabricated using the electrode of TiO2 NTs and Ru(II) complex (Ru(bpy)2+(3)) as a luminescence materials. The fabricated ECL cell is composed of F-doped SnO2 (FTO) glass/Ru(II)/TiO2 NTs/Ti plate. At a bias voltage of 3 V, the measured ECL efficiencies were 0 Im/W for cell without NTs, 0.03 Im/W for NTs-6.5 µm, 0.07 Im/W for NTs-8 µm and 0.1 Im/W for NTs-10 µm, respectively. The use of Ti02 NTs increases ECL intensities by about 2 times compared to the typical ECL cell without the use of TiO2 NTs.

  17. Pt deposited TiO2 catalyst fabricated by thermal decomposition of titanium complex for solar hydrogen production

    NASA Astrophysics Data System (ADS)

    Truong, Quang Duc; Le, Thanh Son; Ling, Yong-Chien

    2014-12-01

    C, N codoped TiO2 catalyst has been synthesized by thermal decomposition of a novel water-soluble titanium complex. The structure, morphology, and optical properties of the synthesized TiO2 catalyst were characterized by X-ray diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy, and UV-vis diffuse reflectance spectroscopy. The photocatalytic activity of the Pt deposited TiO2 catalysts synthesized at different temperatures was evaluated by means of hydrogen evolution reaction under both UV-vis and visible light irradiation. The investigation results reveal that the photocatalytic H2 evolution rate strongly depended on the crystalline grain size as well as specific surface area of the synthesized catalyst. Our studies successfully demonstrate a simple method for the synthesis of visible-light responsive Pt deposited TiO2 catalyst for solar hydrogen production.

  18. Improved Performance of Dye-Sensitized Solar Cells Fabricated from a Coumarin NKX-2700 Dye-Sensitized TiO2/MgO Core-Shell Photoanode with an HfO2 Blocking Layer and a Quasi-Solid-State Electrolyte

    NASA Astrophysics Data System (ADS)

    Maheswari, D.; Venkatachalam, P.

    2015-03-01

    Dye sensitized solar cells (DSSC) were fabricated from a coumarin NKX-2700 dye-sensitized core-shell photoanode and a quasi-solid-state electrolyte, sandwiched together, with a cobalt sulfide-coated counter electrode. The core-shell photoanode consisted of a composite mixture of 90% TiO2 nanoparticles and 10% TiO2 nanowires (TNPW) as core layer and MgO nanoparticles (MNP) as shell layer. Hafnium oxide (HfO2) was applied to the core-shell photoanode film as a blocking layer. TiO2 nanoparticles, TiO2 nanowires, and TNPW/MNP were characterized by x-ray diffractometry, scanning electron microscopy, and transmission electron microscopy. It was apparent from the UV-visible spectrum of the sensitizing dye coumarin NKX-2700 that its absorption was maximum at 525 nm. Power conversion efficiency (PCE) was greater for DSSC-1, fabricated with a core-shell TNPW/MNP/HfO2 photoanode, than for the other DSSC; its photovoltaic properties were: short circuit photocurrent J sc = 19 mA/cm2, open circuit voltage ( V oc) = 720 mV, fill factor ( FF) = 66%, and PCE ( η) = 9.02%. The charge-transport and charge-recombination behavior of the DSSC were investigated by electrochemical impedance spectroscopy; the results showed that the composite core-shell film resulted in the lowest charge-transfer resistance ( R CE) and the longest electron lifetime ( τ eff). Hence, the improved performance of DSSC-1 could be ascribed to the core-shell photoanode with blocking layer, which increased electron transport and suppressed recombination of charge carriers at the photoanode/dye/electrolyte interface.

  19. Detecting HER2 on cancer cells by TiO2 spheres Mie scattering.

    PubMed

    Tsai, Min-Chiao; Tsai, Tsung-Lin; Shieh, Dar-Bin; Chiu, Hsin-Tien; Lee, Chi-Young

    2009-09-15

    This work is the first to describe a bioimaging method that uses highly uniformly sized TiO(2) submicrometer and micrometer spheres based on Mie scattering. Transmembrane proteins (HER2) located on the surface of cancer cells were detected by bonded antibody-linked TiO(2) spheres using optic microscopy and UV-vis spectroscopy. A particular HER2 bond on cancer cells, which has a weaker binding affinity than the biotin/avidin interaction, can be identified between TiO(2) spheres that are linked to anti-HER2 antibodies and those that are linked to nonspecific mouse IgG antibodies by observing the cells under an optical microscope or by measuring absorbance from a UV-vis spectrum. The TiO(2) spheres used in this work was prepared by reacting TTIP with carboxylic acid, as described elsewhere and the uniformity of the TiO(2) sphere was further improved by adjusting the amount of water used. The water content was inversely related to particle size and the size distribution: as more water was used, smaller spheres with a narrower size distribution were obtained. The most uniform sphere obtained had a diameter of about 1 microm with a size variation of 3%. PMID:19653662

  20. Nanoscale TiO2 and Fe2O3 Architectures for Solar Energy Conversion Schemes

    NASA Astrophysics Data System (ADS)

    Sedach, Pavel Anatolyvich

    The direct conversion of sunlight into more useable forms of energy has the potential of alleviating the environmental and social problems associated with a dependence on fossil fuels. If solar energy is to be utilized en-masse, however, it must be inexpensive and widely available. In this vein, the focus of this thesis is on nanostructured materials relevant to solar energy conversion and storage. Specifically, this thesis describes the ambient sol-gel synthesis of titanium dioxide (Ti02) nanowires designed for enhanced charge-transfer in solar collection devices, and the synthesis of novel disordered metal-oxide (MOx) catalysts for water oxidation. The introductory chapter of this thesis gives an overview of the various approaches to solar energy conversion. Sol---gel reaction conditions that enable the growth of one-dimensional (1-D) anatase TiO2 nanostructures from fluorine-doped tin oxide (FTO) for photovoltaics (PVs) are described in the second chapter. The generation of these linear nanostructures in the absence of an external bias or template is achieved by using facile experimental conditions (e.g., acetic acid (HOAc) and titanium isopropoxide (Ti(OiPr)4) in anhydrous heptane). The procedure was developed by functionalizing base-treated substrates with Ti-oxide nucleation sites that serve as a foundation for the growth of linear Ti-oxide macromolecules, which upon calcination, render uniform films of randomly oriented anatase TiO2 nanowires. A systematic evaluation of how reaction conditions (e.g., solvent volume, stoichiometry of reagents, substrate base treatment) affect the generation of these TiO 2 films is presented. A photo-organic MO. deposition route (i.e., photochemical metal-organic deposition (PMOD)) used to deposit thin-films of amorphous iron oxide (a-Fe2O3) for water oxidation catalysis is detailed in third chapter. It is shown that the irradiation of a spin-coated metal-organic film produces a film of non-crystalline a-Fe203. It is shown

  1. Photopatterning Proteins and Cells in Aqueous Environment Using TiO2 Photocatalysis.

    PubMed

    Yamamoto, Hideaki; Demura, Takanori; Sekine, Kohei; Kono, Sho; Niwano, Michio; Hirano-Iwata, Ayumi; Tanii, Takashi

    2015-01-01

    Organic contaminants adsorbed on the surface of titanium dioxide (TiO2) can be decomposed by photocatalysis under ultraviolet (UV) light. Here we describe a novel protocol employing the TiO2 photocatalysis to locally alter cell affinity of the substrate surface. For this experiment, a thin TiO2 film was sputter-coated on a glass coverslip, and the TiO2 surface was subsequently modified with an organosilane monolayer derived from octadecyltrichlorosilane (OTS), which inhibits cell adhesion. The sample was immersed in a cell culture medium, and focused UV light was irradiated to an octagonal region. When a neuronal cell line PC12 cells were plated on the sample, cells adhered only on the UV-irradiated area. We further show that this surface modification can also be performed in situ, i.e., even when cells are growing on the substrate. Proper modification of the surface required an extracellular matrix protein collagen to be present in the medium at the time of UV irradiation. The technique presented here can potentially be employed in patterning multiple cell types for constructing coculture systems or to arbitrarily manipulate cells under culture. PMID:26554338

  2. Photopatterning Proteins and Cells in Aqueous Environment Using TiO2 Photocatalysis.

    PubMed

    Yamamoto, Hideaki; Demura, Takanori; Sekine, Kohei; Kono, Sho; Niwano, Michio; Hirano-Iwata, Ayumi; Tanii, Takashi

    2015-10-26

    Organic contaminants adsorbed on the surface of titanium dioxide (TiO2) can be decomposed by photocatalysis under ultraviolet (UV) light. Here we describe a novel protocol employing the TiO2 photocatalysis to locally alter cell affinity of the substrate surface. For this experiment, a thin TiO2 film was sputter-coated on a glass coverslip, and the TiO2 surface was subsequently modified with an organosilane monolayer derived from octadecyltrichlorosilane (OTS), which inhibits cell adhesion. The sample was immersed in a cell culture medium, and focused UV light was irradiated to an octagonal region. When a neuronal cell line PC12 cells were plated on the sample, cells adhered only on the UV-irradiated area. We further show that this surface modification can also be performed in situ, i.e., even when cells are growing on the substrate. Proper modification of the surface required an extracellular matrix protein collagen to be present in the medium at the time of UV irradiation. The technique presented here can potentially be employed in patterning multiple cell types for constructing coculture systems or to arbitrarily manipulate cells under culture.

  3. Cu2ZnSnS4 Nanoparticle Sensitized Metal-Organic Framework Derived Mesoporous TiO2 as Photoanodes for High-Performance Dye-Sensitized Solar Cells.

    PubMed

    Tang, Rui; Xie, Zhirun; Zhou, Shujie; Zhang, Yanan; Yuan, Zhimin; Zhang, Luyuan; Yin, Longwei

    2016-08-31

    We present a facile hot injection and hydrothermal method to synthesize Cu2ZnSnS4 (CZTS) nanoparticles sensitized metal-organic frameworks (MOFs)-derived mesoporous TiO2. The MOFs-derived TiO2 inherits the large specific surface area and abundantly porous structures of the MOFs structure, which is of great benefit to effectively enhance the dye loading capacity, prolong the incident light traveling length by enhancing the multiple interparticle light-scattering process, and therefore improve the light absorption capacity. The sensitization of CZTS nanoparticles effectively enlarges the photoresponse range of TiO2 to the visible light region and facilitates photoinduced carrier transport. The formed heterostructure between CZTS nanoparticles and MOFs-derived TiO2 with matched band gap structure effectively suppresses the recombination rates of photogenerated electron/hole pairs and prolongs the lifespan of the carriers. Photoanodes based upon CZTS/MOFs-derived TiO2 photoanodes can achieve the maximal photocurrent of 17.27 mA cm(-2) and photoelectric conversion performance of 8.10%, nearly 1.93 and 2.21 times higher than those of TiO2-based photoanode. The related mechanism and model are investigated. The strikingly improved photoelectric properties are ascribed to a synergistic action between the MOFs-derived TiO2 and the sensitization of CZTS nanoparticles.

  4. Cu2ZnSnS4 Nanoparticle Sensitized Metal-Organic Framework Derived Mesoporous TiO2 as Photoanodes for High-Performance Dye-Sensitized Solar Cells.

    PubMed

    Tang, Rui; Xie, Zhirun; Zhou, Shujie; Zhang, Yanan; Yuan, Zhimin; Zhang, Luyuan; Yin, Longwei

    2016-08-31

    We present a facile hot injection and hydrothermal method to synthesize Cu2ZnSnS4 (CZTS) nanoparticles sensitized metal-organic frameworks (MOFs)-derived mesoporous TiO2. The MOFs-derived TiO2 inherits the large specific surface area and abundantly porous structures of the MOFs structure, which is of great benefit to effectively enhance the dye loading capacity, prolong the incident light traveling length by enhancing the multiple interparticle light-scattering process, and therefore improve the light absorption capacity. The sensitization of CZTS nanoparticles effectively enlarges the photoresponse range of TiO2 to the visible light region and facilitates photoinduced carrier transport. The formed heterostructure between CZTS nanoparticles and MOFs-derived TiO2 with matched band gap structure effectively suppresses the recombination rates of photogenerated electron/hole pairs and prolongs the lifespan of the carriers. Photoanodes based upon CZTS/MOFs-derived TiO2 photoanodes can achieve the maximal photocurrent of 17.27 mA cm(-2) and photoelectric conversion performance of 8.10%, nearly 1.93 and 2.21 times higher than those of TiO2-based photoanode. The related mechanism and model are investigated. The strikingly improved photoelectric properties are ascribed to a synergistic action between the MOFs-derived TiO2 and the sensitization of CZTS nanoparticles. PMID:27494761

  5. Superiority of solar Fenton oxidation over TiO2 photocatalysis for the degradation of trimethoprim in secondary treated effluents.

    PubMed

    Michael, I; Hapeshi, E; Michael, C; Fatta-Kassinos, D

    2013-01-01

    The overall aim of this work was to examine the degradation of trimethoprim (TMP), which is an antibacterial agent, during the application of two advanced oxidation process (AOP) systems in secondary treated domestic effluents. The homogeneous solar Fenton process (hv/Fe(2+)/H2O2) and heterogeneous photocatalysis with titanium dioxide (TiO2) suspensions were tested. It was found that the degradation of TMP depends on several parameters such as the amount of iron salt and H2O2, concentration of TiO2, pH of solution, solar irradiation, temperature and initial substrate concentration. The optimum dosages of Fe(2+) and H2O2 for homogeneous ([Fe(2+)] = 5 mg L(-1), [H2O2] = 3.062 mmol L(-1)) and TiO2 ([TiO2] = 3 g L(-1)) for heterogeneous photocatalysis were established. The study indicated that the degradation of TMP during the solar Fenton process is described by a pseudo-first-order reaction and the substrate degradation during the heterogeneous photocatalysis by the Langmuir-Hinshelwood kinetics. The toxicity of the treated samples was evaluated using a Daphnia magna bioassay and was finally decreased by both processes. The results indicated that solar Fenton is more effective than the solar TiO2 process, yielding complete degradation of the examined substrate within 30 min of illumination and dissolved organic carbon (DOC) reduction of about 44% whereas the respective values for the TiO2 process were ∼70% degradation of TMP within 120 min of treatment and 13% DOC removal.

  6. Aperiodic TiO2 nanotube photonic crystal: full-visible-spectrum solar light harvesting in photovoltaic devices.

    PubMed

    Guo, Min; Xie, Keyu; Wang, Yu; Zhou, Limin; Huang, Haitao

    2014-09-23

    Bandgap engineering of a photonic crystal is highly desirable for photon management in photonic sensors and devices. Aperiodic photonic crystals (APCs) can provide unprecedented opportunities for much more versatile photon management, due to increased degrees of freedom in the design and the unique properties brought about by the aperiodic structures as compared to their periodic counterparts. However, many efforts still remain on conceptual approaches, practical achievements in APCs are rarely reported due to the difficulties in fabrication. Here, we report a simple but highly controllable current-pulse anodization process to design and fabricate TiO2 nanotube APCs. By coupling an APC into the photoanode of a dye-sensitized solar cell, we demonstrate the concept of using APC to achieve nearly full-visible-spectrum light harvesting, as evidenced by both experimental and simulated results. It is anticipated that this work will lead to more fruitful practical applications of APCs in high-efficiency photovoltaics, sensors and optoelectronic devices.

  7. Solar Disinfection of Water by TiO2 Photoassisted Processes: Physicochemical, Biological, and Engineering Aspects

    NASA Astrophysics Data System (ADS)

    Rincón, Angela Guiovana; Pulgarin, Cesar

    In this chapter, an overview of photocatalytic bacterial inactivation is given together with recent relevant literature examples and references. The most important parameters influencing the process are classified in physicochemical, biological, and engineering aspects. Experiments carried out at laboratory and field scale are illustrated and discussed. Limitations, advantages, and drawbacks are pointed out. Sensitivity of bacteria to solar disinfection in the absence and presence of TiO2 can vary for each species of microorganism according to strain, stage of the culture, growth medium, initial bacterial load, and type of plating medium used for bacterial cultivation and counting. Physicochemical parameters and reactor design among others also influence the process. However, to comply with requirements in the disinfection systems, it is important to determine for each condition the length of the irradiation period or effective disinfection time (EDT) that ensures death of the bacteria and consequently the end of the treatment.

  8. Evaluation of solar photocatalysis using TiO2 slurry in the inactivation of Cryptosporidium parvum oocysts in water.

    PubMed

    Abeledo-Lameiro, María Jesús; Ares-Mazás, Elvira; Gómez-Couso, Hipólito

    2016-10-01

    Cryptosporidium is a genus of enteric protozoan parasites of medical and veterinary importance, whose oocysts have been reported to occur in different types of water worldwide, offering a great resistant to the water treatment processes. Heterogeneous solar photocatalysis using titanium dioxide (TiO2) slurry was evaluated on inactivation of Cryptosporidium parvum oocysts in water. Suspensions of TiO2 (0, 63, 100 and 200mg/L) in distilled water (DW) or simulated municipal wastewater treatment plant (MWTP) effluent spiked with C. parvum oocysts were exposed to simulated solar radiation. The use of TiO2 slurry at concentrations of 100 and 200mg/L in DW yielded a high level of oocyst inactivation after 5h of exposure (4.16±2.35% and 15.03±4.54%, respectively, vs 99.33±0.58%, initial value), representing a good improvement relative to the results obtained in the samples exposed without TiO2 (51.06±9.35%). However, in the assays carried out using simulated MWTP effluent, addition of the photocatalyst did not offer better results. Examination of the samples under bright field and epifluorescence microscopy revealed the existence of aggregates comprising TiO2 particles and parasitic forms, which size increased as the concentration of catalyst and the exposure time increased, while the intensity of fluorescence of the oocyst walls decreased. After photocatalytic disinfection process, the recovery of TiO2 slurry by sedimentation provided a substantial reduction in the parasitic load in treated water samples (57.81±1.10% and 82.10±2.64% for 200mg/L of TiO2 in DW and in simulated MWTP effluent, respectively). Although further studies are need to optimize TiO2 photocatalytic disinfection against Cryptosporidium, the results obtained in the present study show the effectiveness of solar photocatalysis using TiO2 slurry in the inactivation of C. parvum oocysts in distilled water.

  9. Evaluation of solar photocatalysis using TiO2 slurry in the inactivation of Cryptosporidium parvum oocysts in water.

    PubMed

    Abeledo-Lameiro, María Jesús; Ares-Mazás, Elvira; Gómez-Couso, Hipólito

    2016-10-01

    Cryptosporidium is a genus of enteric protozoan parasites of medical and veterinary importance, whose oocysts have been reported to occur in different types of water worldwide, offering a great resistant to the water treatment processes. Heterogeneous solar photocatalysis using titanium dioxide (TiO2) slurry was evaluated on inactivation of Cryptosporidium parvum oocysts in water. Suspensions of TiO2 (0, 63, 100 and 200mg/L) in distilled water (DW) or simulated municipal wastewater treatment plant (MWTP) effluent spiked with C. parvum oocysts were exposed to simulated solar radiation. The use of TiO2 slurry at concentrations of 100 and 200mg/L in DW yielded a high level of oocyst inactivation after 5h of exposure (4.16±2.35% and 15.03±4.54%, respectively, vs 99.33±0.58%, initial value), representing a good improvement relative to the results obtained in the samples exposed without TiO2 (51.06±9.35%). However, in the assays carried out using simulated MWTP effluent, addition of the photocatalyst did not offer better results. Examination of the samples under bright field and epifluorescence microscopy revealed the existence of aggregates comprising TiO2 particles and parasitic forms, which size increased as the concentration of catalyst and the exposure time increased, while the intensity of fluorescence of the oocyst walls decreased. After photocatalytic disinfection process, the recovery of TiO2 slurry by sedimentation provided a substantial reduction in the parasitic load in treated water samples (57.81±1.10% and 82.10±2.64% for 200mg/L of TiO2 in DW and in simulated MWTP effluent, respectively). Although further studies are need to optimize TiO2 photocatalytic disinfection against Cryptosporidium, the results obtained in the present study show the effectiveness of solar photocatalysis using TiO2 slurry in the inactivation of C. parvum oocysts in distilled water. PMID:27543761

  10. Nanoparticle size and combined toxicity of TiO2 and DSLS (surfactant) contribute to lysosomal responses in digestive cells of mussels exposed to TiO2 nanoparticles.

    PubMed

    Jimeno-Romero, A; Oron, M; Cajaraville, M P; Soto, M; Marigómez, I

    2016-10-01

    The aim of this investigation was to understand the bioaccumulation, cell and tissue distribution and biological effects of disodium laureth sulfosuccinate (DSLS)-stabilised TiO2 nanoparticles (NPs) in marine mussels, Mytilus galloprovincialis. Mussels were exposed in vivo to 0.1, 1 and 10 mg Ti/L either as TiO2 NPs (60 and 180 nm) or bulk TiO2, as well as to DSLS alone. A significant Ti accumulation was observed in mussels exposed to TiO2 NPs, which were localised in endosomes, lysosomes and residual bodies of digestive cells, and in the lumen of digestive tubules, as demonstrated by ultrastructural observations and electron probe X-ray microanalysis. TiO2 NPs of 60 nm were internalised within digestive cell lysosomes to a higher extent than TiO2 NPs of 180 nm, as confirmed by the quantification of black silver deposits after autometallography. The latter were localised mainly forming large aggregates in the lumen of the gut. Consequently, lysosomal membrane stability (LMS) was significantly reduced upon exposure to both TiO2 NPs although more markedly after exposure to TiO2-60 NPs. Exposure to bulk TiO2 and to DSLS also affected the stability of the lysosomal membrane. Thus, effects on the lysosomal membrane depended on the nanoparticle size and on the combined biological effects of TiO2 and DSLS.

  11. Remediation of 17-α-ethinylestradiol aqueous solution by photocatalysis and electrochemically-assisted photocatalysis using TiO2 and TiO2/WO3 electrodes irradiated by a solar simulator.

    PubMed

    Oliveira, Haroldo G; Ferreira, Leticia H; Bertazzoli, Rodnei; Longo, Claudia

    2015-04-01

    TiO2 and TiO2/WO3 electrodes, irradiated by a solar simulator in configurations for heterogeneous photocatalysis (HP) and electrochemically-assisted HP (EHP), were used to remediate aqueous solutions containing 10 mg L(-1) (34 μmol L(-1)) of 17-α-ethinylestradiol (EE2), active component of most oral contraceptives. The photocatalysts consisted of 4.5 μm thick porous films of TiO2 and TiO2/WO3 (molar ratio W/Ti of 12%) deposited on transparent electrodes from aqueous suspensions of TiO2 particles and WO3 precursors, followed by thermal treatment at 450 (°)C. First, an energy diagram was organized with photoelectrochemical and UV-Vis absorption spectroscopy data and revealed that EE2 could be directly oxidized by the photogenerated holes at the semiconductor surfaces, considering the relative HOMO level for EE2 and the semiconductor valence band edges. Also, for the irradiated hybrid photocatalyst, electrons in TiO2 should be transferred to WO3 conduction band, while holes move toward TiO2 valence band, improving charge separation. The remediated EE2 solutions were analyzed by fluorescence, HPLC and total organic carbon measurements. As expected from the energy diagram, both photocatalysts promoted the EE2 oxidation in HP configuration; after 4 h, the EE2 concentration decayed to 6.2 mg L(-1) (35% of EE2 removal) with irradiated TiO2 while TiO2/WO3 electrode resulted in 45% EE2 removal. A higher performance was achieved in EHP systems, when a Pt wire was introduced as a counter-electrode and the photoelectrodes were biased at +0.7 V; then, the EE2 removal corresponded to 48 and 54% for the TiO2 and TiO2/WO3, respectively. The hybrid TiO2/WO3, when compared to TiO2 electrode, exhibited enhanced sunlight harvesting and improved separation of photogenerated charge carriers, resulting in higher performance for removing this contaminant of emerging concern from aqueous solution.

  12. Preparation and Solar Light Photocatalytic Activity of N-Doped TiO2-Loaded Halloysite Nanotubes Nanocomposites

    NASA Astrophysics Data System (ADS)

    Cheng, Zhi-Lin; Sun, Wei

    2015-10-01

    A novel method to prepare N-doped TiO2-loaded halloysite nanotubes (N-TiO2/HNTs) nanocomposites was achieved by using the chemical vapor deposition in autoclave. The N-TiO2/HNTs nanocomposites obtained by the different form of the doping N source were studied through a series of characterizations. The XRD, SEM, and TEM characterizations verified the anatase structure of TiO2 nanoparticles with the size of ca.20nm loaded on the outer surface of HNTs. The UV-vis characterization of the N-TiO2/HNTs presented a further red-shift compared to the pure N-TiO2 nanoparticles.. The XPS characterizations confirmed the N element doped into the crystal structure of TiO2 nanoparticles. The photocatalytic activities of N-TiO2/HNTs nanocomposites prepared were evaluated by degradation of phenol at room temperature under simulated solar light irradiation.

  13. TiO2 film/Cu2O microgrid heterojunction with photocatalytic activity under solar light irradiation.

    PubMed

    Zhang, Junying; Zhu, Hailing; Zheng, Shukai; Pan, Feng; Wang, Tianmin

    2009-10-01

    Coupling a narrow-band-gap semiconductor with TiO(2) is an effective method to produce photocatalysts that work under UV-vis light irradiation. Usually photocatalytic coupled-semiconductors exist mainly as powders, and photocatalytic activity is only favored when a small loading amount of narrow-band-gap semiconductor is used. Here we propose a heavy-loading photocatalyst configuration in which 51% of the surface of the TiO(2) film is covered by a Cu(2)O microgrid. The coupled system shows higher photocatalytic activity under solar light irradiation than TiO(2) and Cu(2)O films. This improved performance is due to the efficient charge transfer between the two phases and the similar opportunity each has to be exposed to irradiation and adsorbates. PMID:20355842

  14. Low-temperature preparation of F-doped TiO 2 film and its photocatalytic activity under solar light

    NASA Astrophysics Data System (ADS)

    Xu, Jingjing; Ao, Yanhui; Fu, Degang; Yuan, Chunwei

    2008-03-01

    A novel and simple method for preparing F-doped anatase TiO 2 (defined as FTO) film with high photocatalytic activity was developed using titanium- n-butoxide and NH 4F as TiO 2 and fluorine precursors under mild condition, i.e. low temperature (lower than 373 K) and ambient pressure. The prepared samples were characterized by XRD, SEM, X-ray photoelectron spectroscopy (XPS), diffuse reflectance spectrum (DRS), photoluminescence spectrum (PL) and TG-DSC analysis. The photocatalytic activity was evaluated by decomposing X-3B under artificial solar light. The results showed that the crystallinity of TiO 2 was improved by F-doping. F - ions can prevent the grain growth, and the transformation of anatase to rutile phase was also inhibited. The doped fluorine atoms existed in two chemical forms, and the ones incorporated into TiO 2 lattice might take a positive role in photocatalysis. Compared with surface fluorination samples, FTO film exhibited better photocatalytic activity. The high photocatalytic activity of FTO may due to extrinsic absorption through the creation of oxygen vacancies rather than the excitation of the intrinsic absorption band of bulk TiO 2. Furthermore, the FTO can be recycled with little photocatalytic activity depression. Without any further treatment besides rinsing, after 6 recycle utilization, the photocatalytic activity of FTO film was still higher than 79%.

  15. Effects of TiO2 and Co3O4 Nanoparticles on Circulating Angiogenic Cells

    PubMed Central

    Spigoni, Valentina; Cito, Monia; Alinovi, Rossella; Pinelli, Silvana; Passeri, Giovanni; Zavaroni, Ivana; Goldoni, Matteo; Campanini, Marco; Aliatis, Irene; Mutti, Antonio

    2015-01-01

    Background and Aim Sparse evidence suggests a possible link between exposure to airborne nanoparticles (NPs) and cardiovascular (CV) risk, perhaps through mechanisms involving oxidative stress and inflammation. We assessed the effects of TiO2 and Co3O4 NPs in human circulating angiogenic cells (CACs), which take part in vascular endothelium repair/replacement. Methods CACs were isolated from healthy donors’ buffy coats after culturing lymphomonocytes on fibronectin-coated dishes in endothelial medium for 7 days. CACs were pre-incubated with increasing concentration of TiO2 and Co3O4 (from 1 to 100 μg/ml) to test the effects of NP – characterized by Transmission Electron Microscopy – on CAC viability, apoptosis (caspase 3/7 activation), function (fibronectin adhesion assay), oxidative stress and inflammatory cytokine gene expression. Results Neither oxidative stress nor cell death were associated with exposure to TiO2 NP (except at the highest concentration tested), which, however, induced a higher pro-inflammatory effect compared to Co3O4 NPs (p<0.01). Exposure to Co3O4 NPs significantly reduced cell viability (p<0.01) and increased caspase activity (p<0.01), lipid peroxidation end-products (p<0.05) and pro-inflammatory cytokine gene expression (p<0.05 or lower). Notably, CAC functional activity was impaired after exposure to both TiO2 (p<0.05 or lower) and Co3O4 (p<0.01) NPs. Conclusions In vitro exposure to TiO2 and Co3O4 NPs exerts detrimental effects on CAC viability and function, possibly mediated by accelerated apoptosis, increased oxidant stress (Co3O4 NPs only) and enhancement of inflammatory pathways (both TiO2 and Co3O4 NPs). Such adverse effects may be relevant for a potential role of exposure to TiO2 and Co3O4 NPs in enhancing CV risk in humans. PMID:25803285

  16. Toxicity of ZnO and TiO2 to Escherichia coli cells

    NASA Astrophysics Data System (ADS)

    Leung, Yu Hang; Xu, Xiaoying; Ma, Angel P. Y.; Liu, Fangzhou; Ng, Alan M. C.; Shen, Zhiyong; Gethings, Lee A.; Guo, Mu Yao; Djurišić, Aleksandra B.; Lee, Patrick K. H.; Lee, Hung Kay; Chan, Wai Kin; Leung, Frederick C. C.

    2016-10-01

    We performed a comprehensive investigation of the toxicity of ZnO and TiO2 nanoparticles using Escherichia coli as a model organism. Both materials are wide band gap n-type semiconductors and they can interact with lipopolysaccharide molecules present in the outer membrane of E. coli, as well as produce reactive oxygen species (ROS) under UV illumination. Despite the similarities in their properties, the response of the bacteria to the two nanomaterials was fundamentally different. When the ROS generation is observed, the toxicity of nanomaterial is commonly attributed to oxidative stress and cell membrane damage caused by lipid peroxidation. However, we found that significant toxicity does not necessarily correlate with up-regulation of ROS-related proteins. TiO2 exhibited significant antibacterial activity, but the protein expression profile of bacteria exposed to TiO2 was different compared to H2O2 and the ROS-related proteins were not strongly expressed. On the other hand, ZnO exhibited lower antibacterial activity compared to TiO2, and the bacterial response involved up-regulating ROS-related proteins similar to the bacterial response to the exposure to H2O2. Reasons for the observed differences in toxicity and bacterial response to the two metal oxides are discussed.

  17. Mechanisms of stem cell osteogenic differentiation on TiO2 nanotubes.

    PubMed

    Yu, Weiqiang; Qian, Chao; Jiang, Xinquan; Zhang, Fuqiang; Weng, Weimin

    2015-12-01

    TiO2 nanotubes could stimulate osteogenic differentiation of stem cells, but the molecular mechanisms underlying the interactions between nanotubes and stem cells remain unclear. In this study, we investigated the response of bone marrow stromal cells to nanotubes of different diameters using microarray-based bioinformatics approach. Gene ontology (GO) and GO enrichment network analysis indicated that larger TiO2 nanotubes were more potent than smaller nanotubes in inducing the expression of genes involved in cell proliferation, differentiation, and immune responses, and inhibiting that of genes responsible for cell adhesion. The analysis of the signaling network containing significantly affected genes suggested that Na(+)/K(+) transporting ATPases ATP1A2 (alpha 2 polypeptide) and ATP1A3 (alpha 3 polypeptide), and MAP3K11 (mitogen-activated protein kinase kinase kinase 11) were important for inducing osteogenic differentiation of bone marrow stromal cells without additional osteogenic stimuli. The upregulation of the ATP1A2 and MAP3K11 genes confirmed by real-time PCR indicates that the response of bone marrow stromal cells to nanotube cues may be mediated by the pathways previously implicated in transducing mechanical stress signals. Our results revealed some molecular mechanisms by which TiO2 nanotubes may direct osteogenic differentiation of stem cells.

  18. Modulating the interaction between gold and TiO2 nanowires for enhanced solar driven photoelectrocatalytic hydrogen generation.

    PubMed

    Sudhagar, P; Song, Taeseup; Devadoss, Anitha; Lee, Jung Woo; Haro, Marta; Terashima, Chiaki; Lysak, Volodymyr V; Bisquert, Juan; Fujishima, Akira; Gimenez, Sixto; Paik, Ungyu

    2015-07-15

    The interaction strength of Au nanoparticles with pristine and nitrogen doped TiO2 nanowire surfaces was analysed using density functional theory and their significance in enhancing the solar driven photoelectrocatalytic properties was elucidated. In this article, we prepared 4-dimethylaminopyridine capped Au nanoparticle decorated TiO2 nanowire systems. The density functional theory calculations show {101} facets of TiO2 as the preferred phase for dimethylaminopyridine-Au nanoparticles anchoring with a binding energy of -8.282 kcal mol(-1). Besides, the interaction strength of Au nanoparticles was enhanced nearly four-fold (-35.559 kcal mol(-1)) at {101} facets via nitrogen doping, which indeed amplified the Au nanoparticle density on nitrided TiO2. The Au coated nitrogen doped TiO2 (N-TiO2-Au) hybrid electrodes show higher absorbance owing to the light scattering effect of Au nanoparticles. In addition, N-TiO2-Au hybrid electrodes block the charge leakage from the electrode to the electrolyte and thus reduce the charge recombination at the electrode/electrolyte interface. Despite the beneficial band narrowing effect of nitrogen in TiO2 on the electrochemical and visible light activity in N-TiO2-Au hybrid electrodes, it results in low photocurrent generation at higher Au NP loading (3.4 × 10(-7) M) due to light blocking the N-TiO2 surface. Strikingly, even with a ten-fold lower Au NP loading (0.34 × 10(-7) M), the synergistic effects of nitrogen doping and Au NPs on the N-TiO2-Au hybrid system yield high photocurrent compared to TiO2 and TiO2-Au electrodes. As a result, the N-TiO2-Au electrode produces nearly 270 μmol h(-1) cm(-2) hydrogen, which is nearly two-fold higher than the pristine TiO2 counterpart. The implications of these findings for the design of efficient hybrid photoelectrocatalytic electrodes are discussed.

  19. Assessment of solar driven TiO2-assisted photocatalysis efficiency on amoxicillin degradation.

    PubMed

    Pereira, João H O S; Reis, Ana C; Nunes, Olga C; Borges, Maria T; Vilar, Vítor J P; Boaventura, Rui A R

    2014-01-01

    The objective of this work was to evaluate the efficiency of a solar TiO2-assisted photocatalytic process on amoxicillin (AMX) degradation, an antibiotic widely used in human and veterinary medicine. Firstly, solar photolysis of AMX was compared with solar photocatalysis in a compound parabolic collectors pilot scale photoreactor to assess the amount of accumulated UV energy in the system (Q UV) necessary to remove 20 mg L(-1) AMX from aqueous solution and mineralize the intermediary by-products. Another experiment was also carried out to accurately follow the antibacterial activity against Escherichia coli DSM 1103 and Staphylococcus aureus DSM 1104 and mineralization of AMX by tracing the contents of dissolved organic carbon (DOC), low molecular weight carboxylate anions, and inorganic anions. Finally, the influence of individual inorganic ions on AMX photocatalytic degradation efficiency and the involvement of some reactive oxygen species were also assessed. Photolysis was shown to be completely ineffective, while only 3.1 kJUV L(-1) was sufficient to fully degrade 20 mg L(-1) AMX and remove 61% of initial DOC content in the presence of the photocatalyst and sunlight. In the experiment with an initial AMX concentration of 40 mg L(-1), antibacterial activity of the solution was considerably reduced after elimination of AMX to levels below the respective detection limit. After 11.7 kJUV L(-1), DOC decreased by 71%; 30% of the AMX nitrogen was converted into ammonium and all sulfur compounds were converted into sulfate. A large percentage of the remaining DOC was in the form of low molecular weight carboxylic acids. Presence of phosphate ions promoted the removal of AMX from solution, while no sizeable effects on the kinetics were found for other inorganic ions. Although the AMX degradation was mainly attributed to hydroxyl radicals, singlet oxygen also plays an important role in AMX self-photosensitization under UV/visible solar light.

  20. Activities of Combined TiO2 Semiconductor Nanocatalysts Under Solar Light on the Reduction of CO2.

    PubMed

    Liu, Hongfang; Dao, Anh Quang; Fu, Chaoyang

    2016-04-01

    The materials based on TiO2 semiconductors are a promising option for electro-photocatalytic systems working as solar energy low-carbon fuels exchanger. These materials' structures are modified by doping metals and metal oxides, by metal sulfides sensitization, or by graphene supported membrane, enhancing their catalytic activity. The basic phenomenon of CO2 reduction to CH4 on Pd modified TiO2 under UV irradiation could be enhanced by Pd, or RuO2 co-doped TiO2. Sensitization with metal sulfide QDs is effective by moving of photo-excited electron from QDs to TiO2 particles. Based on characteristics of the catalysts various combinations of catalysts are proposed in order to creat catalyst systems with good CO2 reduction efficiency. From this critical review of the CO2 reduction to organic compounds by converting solar light and CO2 to storable fuels it is clear that more studies are still attractive and needed. PMID:27451648

  1. Synthesis of Nanoscale TiO2 and Study of the Effect of Their Crystal Structure on Single Cell Response

    PubMed Central

    Ismagilov, Z. R.; Shikina, N. V.; Mazurkova, N. A.; Tsikoza, L. T.; Tuzikov, F. V.; Ushakov, V. A.; Ishchenko, A. V.; Rudina, N. A.; Korneev, D. V.; Ryabchikova, E. I.

    2012-01-01

    To study the effect of nanoscale titanium dioxide (TiO2) on cell responses, we synthesized four modifications of the TiO2 (amorphous, anatase, brookite, and rutile) capable of keeping their physicochemical characteristics in a cell culture medium. The modifications of nanoscale TiO2 were obtained by hydrolysis of TiCl4 and Ti(i-OC3H7)4 (TIP) upon variation of the synthesis conditions; their textural, morphological, structural, and dispersion characteristics were examined by a set of physicochemical methods: XRD, BET, SAXS, DLS, AFM, SEM, and HR-TEM. The effect of synthesis conditions (nature of precursor, pH, temperature, and addition of a complexing agent) on the structural-dispersion properties of TiO2 nanoparticles was studied. The hydrolysis methods providing the preparation of amorphous, anatase, brookite, and rutile modifications of TiO2 nanoparticles 3–5 nm in size were selected. Examination of different forms of TiO2 nanoparticles interaction with MDCK cells by transmission electron microscopy of ultrathin sections revealed different cell responses after treatment with different crystalline modifications and amorphous form of TiO2. The obtained results allowed us to conclude that direct contact of the nanoparticles with cell plasma membrane is the primary and critical step of their interaction and defines a subsequent response of the cell. PMID:22623903

  2. TiO2 nanotube structures for enhanced cell and biological functionality

    NASA Astrophysics Data System (ADS)

    Brammer, Karla S.; Oh, Seunghan; Frandsen, Christine J.; Jin, Sungho

    2010-04-01

    Nanostructures have pronounced effects on biological processes such as growth of cells and their functionality. Advances in biomaterial surface structure and design have resulted in improved tissue engineering. Nanotechnology can be utilized for optimization of titanium implants with a formation of vertically aligned TiO2 nanotube arrays on the implant surface. The anodic oxidation of the titanium implant surface to form a TiO2 nanotube array involves electrochemical processes and self assembly. In this paper, the mechanism of nanotube formation, nanotube bio-characteristics, and their emerging role in soft and hard tissue engineering as well as in regenerative medicine will be reviewed, and the beneficial effects of surface nanotubes on cell adhesion, proliferation, and functionality will be discussed in relation to potential orthopedics applications.

  3. Solar photolysis versus TiO2-mediated solar photocatalysis: a kinetic study of the degradation of naproxen and diclofenac in various water matrices.

    PubMed

    Kanakaraju, Devagi; Motti, Cherie A; Glass, Beverley D; Oelgemöller, Michael

    2016-09-01

    Given that drugs and their degradation products are likely to occur as concoctions in wastewater, the degradation of a mixture of two nonsteroidal anti-inflammatory drugs (NSAIDs), diclofenac (DCF) and naproxen (NPX), was investigated by solar photolysis and titanium dioxide (TiO2)-mediated solar photocatalysis using an immersion-well photoreactor. An equimolar ratio (1:1) of both NSAIDs in distilled water, drinking water, and river water was subjected to solar degradation. Solar photolysis of the DCF and NPX mixture was competitive particularly in drinking water and river water, as both drugs have the ability to undergo photolysis. However, the addition of TiO2 in the mixture significantly enhanced the degradation rate of both APIs compared to solar photolysis alone. Mineralization, as measured by chemical oxygen demand (COD), was incomplete under all conditions investigated. TiO2-mediated solar photocatalytic degradation of DCF and NPX mixtures produced 15 identifiable degradants corresponding to degradation of the individual NSAIDs, while two degradation products with much higher molecular weight than the parent NSAIDs were identified by liquid chromatography mass spectrometry (LC-MS) and Fourier transform-ion cyclotron resonance-mass spectrometry (FT-ICR-MS). This study showed that the solar light intensity and the water matrix appear to be the main factors influencing the overall performance of the solar photolysis and TiO2-mediated solar photocatalysis for degradation of DCF and NPX mixtures. PMID:27230148

  4. Solar photolysis versus TiO2-mediated solar photocatalysis: a kinetic study of the degradation of naproxen and diclofenac in various water matrices.

    PubMed

    Kanakaraju, Devagi; Motti, Cherie A; Glass, Beverley D; Oelgemöller, Michael

    2016-09-01

    Given that drugs and their degradation products are likely to occur as concoctions in wastewater, the degradation of a mixture of two nonsteroidal anti-inflammatory drugs (NSAIDs), diclofenac (DCF) and naproxen (NPX), was investigated by solar photolysis and titanium dioxide (TiO2)-mediated solar photocatalysis using an immersion-well photoreactor. An equimolar ratio (1:1) of both NSAIDs in distilled water, drinking water, and river water was subjected to solar degradation. Solar photolysis of the DCF and NPX mixture was competitive particularly in drinking water and river water, as both drugs have the ability to undergo photolysis. However, the addition of TiO2 in the mixture significantly enhanced the degradation rate of both APIs compared to solar photolysis alone. Mineralization, as measured by chemical oxygen demand (COD), was incomplete under all conditions investigated. TiO2-mediated solar photocatalytic degradation of DCF and NPX mixtures produced 15 identifiable degradants corresponding to degradation of the individual NSAIDs, while two degradation products with much higher molecular weight than the parent NSAIDs were identified by liquid chromatography mass spectrometry (LC-MS) and Fourier transform-ion cyclotron resonance-mass spectrometry (FT-ICR-MS). This study showed that the solar light intensity and the water matrix appear to be the main factors influencing the overall performance of the solar photolysis and TiO2-mediated solar photocatalysis for degradation of DCF and NPX mixtures.

  5. Physical properties of as-prepared and post-annealed TiO2 layers by atomic layer deposition and their cell performance

    NASA Astrophysics Data System (ADS)

    Kim, Min Ji; Ahn, Kyun; Choi, Hun Seok; Pham-Cong, De; Gao, Ying Jun; Cho, Jin Hyuk; Park, Cheul Un; Cho, Chae-Ryong

    2016-01-01

    We report on the physical properties of TiO2 blocking layers with various thicknesses in both the as-prepared and the post-annealed states and on their cell performances in dye-sensitized solar cells (DSSCs). The TiO2 layers of various thicknesses (up to 50 nm) were prepared on fluorine-doped SnO2/glass substrates by using atomic layer deposition. The electron lifetime of the DSSCs was observed to depend critically on both the thickness and the annealing treatment for TiO2 layers with thicknesses up to 10 nm. However, for thicknesses above 20 nm, the cell performance of the DSSCs decreased because of increases in the defect density and charge recombination. We conclude that the cell efficiency of DSSCs with a 10-nm-thick TiO2 layer is higher than those of DSSCs with layers of other thicknesses; in addition, the cell characteristics of the post-annealed structures were better than those of the as-prepared ones.

  6. Azo-dyes photocatalytic degradation in aqueous suspension of TiO2 under solar irradiation.

    PubMed

    Augugliaro, Vincenzo; Baiocchi, Claudio; Prevot, Alessandra Bianco; García-López, Elisa; Loddo, Vittorio; Malato, Sixto; Marcí, Giuseppe; Palmisano, Leonardo; Pazzi, Marco; Pramauro, Edmondo

    2002-12-01

    The photodegradation of two common and very stable azo-dyes, i.e. methyl-orange (C14H14N3SO3Na) and orange II (C16H11N2SO4Na), is reported. The photocatalytic oxidation was carried out in aqueous suspensions of polycrystalline TiO2 irradiated by sunlight. Compound parabolic collectors, installed at the "Plataforma Solar de Almería" (PSA, Spain) were used as the photoreactors and two identical reacting systems allowed to perform photoreactivity runs for the two dyes at the same time and under the same irradiation conditions. The disappearance of colour and substrates together with the abatement of total organic carbon content was monitored. The main sulfonate-containing intermediates were found to be in lower number in respect to those obtained under artificial irradiation. In particular there were no more evidence of the presence of hydroxylated transients. The dependence of dye photooxidation rate on: (i) substrate concentration; (ii) catalyst amount; and (iii) initial pH was investigated. The influence of the presence of strong oxidant species (H2O2, S2O8(2-)) and some ions (Cl-, SO4(2-)) on the process was also studied.

  7. Effect of anatase TiO2 nanoparticles on the growth of RSC-364 rat synovial cell.

    PubMed

    Wang, Jiangxue; Ma, Jiawei; Dong, Linmeng; Hou, Ying; Jia, Xiaoling; Niu, Xufeng; Fan, Yubo

    2013-06-01

    Nanoscale materials (such as TiO2, hydroxyapatite nanoparticles) have gained much concern in the coating of implants for cell adhesion and growth to improve the osteoconductivity. However, due to attrition and corrosion, the wear particles would be generated from the joint in living organism, and influence the physiological function of synovial membranes in joint cavity. In this study, the potential cytotoxicity of anatase TiO2 nanoparticles (TiO2 NPs) on rat synovial cell line 364 (RSC-364) was investigated. After treatment with different concentrations of TiO2 NPs (0, 3, 30, 300 microg/ml), the viability of RSC-364 cells were decreased in a dose-dependent manner. TiO2 NPs exposure could disrupt the integrity of cell plasma membrane, leading to the increased leakage of lactate dehydrogenase (LDH) into the culture medium. TiO2 NPs were uptaken by RSC-364 cells. The ultrastructure of RSC-364 cells was changed such as nuclear shrinkage and mitochondrial swelling. The reactive oxygen species (ROS) was over-produced especially in the cells exposed to 30 and 300 microg/ml TiO2 NPs. The activities of endogeneous antioxidant enzymes, superoxide dismutase (SOD) and catalase (CAT), were significantly decreased. The increased lipid peroxidation product (malondialdehyde, MDA) suggests the oxidative damage in cells. The flow cytometry detected that the cell cycle was blocked in G0/G1 phase, inhibiting the cell proliferation. These preliminary results indicate the oxidative stress injury and cytotoxicity of anatase TiO2 NPs on rat synovial cells. The reasonable and safe application of nanomaterials in artificial implants needs further study.

  8. Influence of anatase and rutile phase in TiO2 upon the photocatalytic degradation of methylene blue under solar irradiation in presence of activated carbon.

    PubMed

    Matos, J; Montaña, R; Rivero, E; Escudero, A; Uzcategui, D

    2014-01-01

    The influence of activated carbon (AC) on the photocatalytic activity of different crystalline TiO2 phases was verified in the photocatalytic degradation of methylene blue under UV and solar irradiation. The results showed a volcano trend with a maximum photoactivity for the crystalline phase ratio of anatase:rutile equal to 80:20 both under UV or solar irradiation. By contrast, in presence of AC the photocatalytic activity of the binary materials of TiO2/AC followed an exponential trend, increasing as a function of the increase in anatase proportion in the TiO2 framework. The increase in the photoactivity of the binary material TiO2/AC relative to neat TiO2 was up to 22 and about 17 times higher under UV and visible irradiation, respectively. The present results suggest that AC interacts more efficiently with anatase phase than with rutile phase.

  9. Correlation between dispersion properties of TiO2 colloidal sols and photoelectric characteristics of TiO2 films.

    PubMed

    Jung, Hyun Suk; Lee, Sang-Wook; Kim, Jin Young; Hong, Kug Sun; Lee, Young Cheol; Ko, Kyung Hyun

    2004-11-15

    TiO2 film for use as dye-sensitized solar cell was prepared using the TiO2 colloidal sols (unpeptized sol and peptized sol). The optical properties and photocurrent-voltage characteristics of the resultant films were investigated. The optical transmittance of TiO2 thin film prepared from the peptized colloidal sol was over 90%, while that of TiO2 film from the unpeptized sol was under 80%. The TiO2 photoelectrode prepared from the peptized colloidal sol showed low photoelectric conversion efficiency (eta), 1.30%, whereas the efficiency of photoelectrode from the unpeptized sol was 2.21%. The high optical transmittance and low conversion efficiency of TiO2 film from the peptized sol are discussed in terms of dense microstructure due to the drying nature of well-dispersed colloidal sol.

  10. Degradation of Methyl Orange and Congo Red dyes by using TiO2 nanoparticles activated by the solar and the solar-like radiation.

    PubMed

    Ljubas, Davor; Smoljanić, Goran; Juretić, Hrvoje

    2015-09-15

    In this study we used TiO2 nanoparticles as semiconductor photocatalysts for the degradation of Methyl Orange (MO) and Congo Red (CR) dyes in an aqueous solution. Since TiO2 particles become photocatalytically active by UV radiation, two sources of UV-A radiation were used - natural solar radiation which contains 3-5% UV-A and artificial, solar-like radiation, created by using a lamp. The optimal doses of TiO2 of 500 mg/L for the CR and 1500 mg/L for the MO degradation were determined in experiments with the lamp and were also used in degradation experiments with natural solar light. The efficiency of each process was determined by measuring the absorbance at two visible wavelengths, 466 nm for MO and 498 nm for CR, and the total organic carbon (TOC), i.e. decolorization and mineralization, respectively. In both cases, considerable potential for the degradation of CR and MO was observed - total decolorization of the solution was achieved within 30-60 min, while the TOC removal was in the range 60-90%. CR and MO solutions irradiated without TiO2 nanoparticles showed no observable changes in either decolorization or mineralization. Three different commercially available TiO2 nanoparticles were used: pure-phase anatase, pure-phase rutile, and mixed-phase preparation named Degussa P25. In terms of degradation kinetics, P25 TiO2 exhibited a photocatalytic activity superior to that of pure-phase anatase or rutile. The electric energy consumption per gram of removed TOC was determined. For nearly the same degradation effect, the consumption in the natural solar radiation experiment was more than 60 times lower than in the artificial solar-like radiation experiment.

  11. Localized committed differentiation of neural stem cells based on the topographical regulation effects of TiO2 nanostructured ceramics

    NASA Astrophysics Data System (ADS)

    Mou, Xiaoning; Wang, Shu; Guo, Weibo; Ji, Shaozheng; Qiu, Jichuan; Li, Deshuai; Zhang, Xiaodi; Zhou, Jin; Tang, Wei; Wang, Changyong; Liu, Hong

    2016-07-01

    In this study, a porous-flat TiO2 micropattern was fabricated with flat and nanoporous TiO2 ceramics for investigating the effect of topography on neural stem cell (NSC) differentiation. This finding demonstrates that localized committed differentiation could be achieved in one system by integrating materials with different topographies.In this study, a porous-flat TiO2 micropattern was fabricated with flat and nanoporous TiO2 ceramics for investigating the effect of topography on neural stem cell (NSC) differentiation. This finding demonstrates that localized committed differentiation could be achieved in one system by integrating materials with different topographies. Electronic supplementary information (ESI) available. See DOI: 10.1039/c6nr01874b

  12. Hydrogen-doped Brookite TiO2 Nanobullets Array as a Novel Photoanode for Efficient Solar Water Splitting

    PubMed Central

    Choi, Mingi; Lee, June Ho; Jang, Youn Jeong; Kim, Donghyung; Lee, Jae Sung; Jang, Hyun Myung; Yong, Kijung

    2016-01-01

    As a representative photocatalyst for photoelectrochemical solar water splitting, TiO2 has been intensively studied but most researches have focused on the rutile and anatsase phases because brookite, another important crystalline polymorph of TiO2, rarely exists in nature and is difficult to synthesize. In this work, hydrogen doped brookite (H:brookite) nanobullet arrays were synthesized via a well-designed solution reaction for the first time. H:brookite shows highly improved PEC properties with excellent stability, enhanced photocurrent, and significantly high Faradaic efficiency for overall solar water splitting. To support the experimental data, ab initio density functional theory calculations were also conducted. At the interstitial doping site that has minimum formation energy, the hydrogen atoms act as shallow donors and exist as H+. which has the minimum formation energy among three states of hydrogen (H+. H0, and H−). The calculated density of states of H:brookite shows a narrowed bandgap and an increased electron density compared to the pristine brookite. The combined experimental and theoretical results provide frameworks for the exploration of the PEC properties of doped brookite and extend our knowledge regarding the undiscovered properties of brookite of TiO2. PMID:27782198

  13. Aperiodic TiO2 Nanotube Photonic Crystal: Full-Visible-Spectrum Solar Light Harvesting in Photovoltaic Devices

    PubMed Central

    Guo, Min; Xie, Keyu; Wang, Yu; Zhou, Limin; Huang, Haitao

    2014-01-01

    Bandgap engineering of a photonic crystal is highly desirable for photon management in photonic sensors and devices. Aperiodic photonic crystals (APCs) can provide unprecedented opportunities for much more versatile photon management, due to increased degrees of freedom in the design and the unique properties brought about by the aperiodic structures as compared to their periodic counterparts. However, many efforts still remain on conceptual approaches, practical achievements in APCs are rarely reported due to the difficulties in fabrication. Here, we report a simple but highly controllable current-pulse anodization process to design and fabricate TiO2 nanotube APCs. By coupling an APC into the photoanode of a dye-sensitized solar cell, we demonstrate the concept of using APC to achieve nearly full-visible-spectrum light harvesting, as evidenced by both experimental and simulated results. It is anticipated that this work will lead to more fruitful practical applications of APCs in high-efficiency photovoltaics, sensors and optoelectronic devices. PMID:25245854

  14. Structural, optical, and electrical properties of p-type NiO films and composite TiO 2/NiO electrodes for solid-state dye-sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Lee, Yi-Mu; Hsu, Cheng-Hsing; Chen, Hung-Wei

    2009-02-01

    p-Type nickel oxide thin films were prepared by sol-gel method, and their structural, optical and electrical properties were investigated. The Ni(OH) 2 sol was formed from nickel (II) acetate tetrahydrate, Ni(CH 3COO) 2·4H 2O, in a mixture of alcohol solution and poly(ethylene glycol), and deposited on an ITO substrate by spin coating followed by different heat treatments in air (50-800 °C). The formation and composition of NiO thin film was justified by EDX analysis. It is found that the thickness of the NiO film calcined at 450 °C for 1 h is about 120 nm with average particle size of 22 nm, and high UV transparency (˜75%) in the visible region is also observed. However, the transmittance is negligible for thin films calcined at 800 °C and below 200 °C due to larger particle size and the amorphous characteristics, respectively. Moreover, the composite electrode comprising n-type TiO 2 and p-type NiO is fabricated. The current-voltage ( I- V) characteristics of the composite TiO 2/NiO electrode demonstrate significant p-type behavior by the shape of the rectifying curve in dark. The effect of calcination temperature on the rectification behavior is also discussed.

  15. Photocatalytic Destruction of an Organic Dye Using TiO2 and Solar Energy.

    ERIC Educational Resources Information Center

    Giglio, Kimberly D.; And Others

    1995-01-01

    Describes a general chemistry experiment that is carried out in sunlight to illustrate the ability of TiO2 to act as a photocatalyst by mineralizing an organic dye into carbon dioxide. Details about the construction of the reactor system used to perform this experiment are included. (DDR)

  16. Cobalt phosphate modified TiO2 nanowire arrays as co-catalysts for solar water splitting

    NASA Astrophysics Data System (ADS)

    Ai, Guanjie; Mo, Rong; Li, Hongxing; Zhong, Jianxin

    2015-04-01

    Cobalt phosphate (Co-Pi) is photo-electrodeposited on TiO2 nanowire arrays in Co2+ containing phosphate buffer. The resulting composite photoanode shows a generally enhanced photocurrent near the flat band potential region, and represents a 2.3 times improved photoconversion efficiency compared to that of pristine TiO2 in a neutral electrolyte. A negative effect on the photocurrent generation is also observed when loading TiO2 with a relatively thick Co-Pi layer, which is demonstrated to be due to the poor photohole transfer kinetics in the Co-Pi layer. Moreover, we find that Co-Pi can facilitate the photoelectrochemical performance of TiO2 over a wide pH range from 1-14. This improved activity is studied in detail by optical and electrochemical analyses. It is suggested that the mechanism of the overpotential-demanding water oxidation reaction is changed to a facile pathway by the Co-based electrocatalyst. At the same time, the more significant band bending is induced by the Co-Pi catalyst decreasing the charge recombination. This work provides a feasible route to reduce the external power needed to drive water splitting by coupling an electrocatalyst with a photocatalyst, as well as mechanistic insights important for other Co-Pi modified photoelectrodes for solar-driven water splitting.Cobalt phosphate (Co-Pi) is photo-electrodeposited on TiO2 nanowire arrays in Co2+ containing phosphate buffer. The resulting composite photoanode shows a generally enhanced photocurrent near the flat band potential region, and represents a 2.3 times improved photoconversion efficiency compared to that of pristine TiO2 in a neutral electrolyte. A negative effect on the photocurrent generation is also observed when loading TiO2 with a relatively thick Co-Pi layer, which is demonstrated to be due to the poor photohole transfer kinetics in the Co-Pi layer. Moreover, we find that Co-Pi can facilitate the photoelectrochemical performance of TiO2 over a wide pH range from 1-14. This

  17. Fabrication characterization and activity of a solar light driven photocatalyst: cerium doped TiO2 magnetic nanofibers.

    PubMed

    Li, Cong-Ju; Wang, Bin; Wang, Jiao-Na

    2012-03-01

    A novel magnetic separable composite photocatalytic nanofiber consisting of TiO2 as the major phase, CeO(2-y) and CoFe2O4 as the dopant phase was prepared by sol-gel method and electrospinning technique, and characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), UV-vis diffuse reflectance spectrum (UV-vis DRS) and vibrating sample magnetometer (VSM). The photocatalytic activity of the resultant CoFe2O4-TiO2 and CeO(2-y)/CoFe2O4-TiO2 nanofibers was evaluated by photodegradation of methylene blue (MB) in an aqueous solution under xenon lamp (the irradiation spectrum energy distribution is similar to sunlight) irradiation in a photochemical reactor. The results showed that the dopant of Ce could affect the absorbance ability and photo-response range. The sample containing 1.0 wt% CeO(2-y) exhibited the highest degradation with 35% for MB under simulate solar light irradiation. Furthermore, the as-synthesized composite photocatalytic nanofibers could be separated easily by an external magnetic field, thus it might hold potential for application in wastewater treatment.

  18. Metal oxide nanocluster-modified TiO2 as solar activated photocatalyst materials

    NASA Astrophysics Data System (ADS)

    Fronzi, Marco; Iwaszuk, Anna; Lucid, Aoife; Nolan, Michael

    2016-02-01

    In this review we describe our work on new TiO2 based photocatalysts. The key concept in our work is to form new composite structures by the modification of rutile and anatase TiO2 with nanoclusters of metal oxides and our density functional theory (DFT) level simulations are validated by experimental work synthesizing and characterizing surface-modified TiO2. We use DFT to show that nanoclusters of different metal oxides, TiO2, SnO/SnO2, PbO/PbO2, NiO and CuO can be adsorbed at rutile and anatase surfaces and can induce red shifts in the absorption edge to enable visible light absorption which is the first key requirement for a practical photocatalyst. We furthermore determine the origin of the red shift and discuss the factors influencing this shift and the fate of excited electrons and holes. For p-block metal oxides we show how the oxidation state of Sn and Pb can be used to tune both the magnitude of the red shift and also its mechanism. Finally, aiming to make our models more realistic, we present some new results on the stability of water at rutile and anatase surfaces and the effect of water on oxygen vacancy formation and on nanocluster modification. These nanocluster-modified TiO2 structures form the basis of a new class of photocatalysts which will be useful in oxidation reactions and with the suitable choice of nanocluster modifier can be applied to CO2 reduction.

  19. TiO2 Nanorod Array Constructed Nanotopography for Regulation of Mesenchymal Stem Cells Fate and the Realization of Location-Committed Stem Cell Differentiation.

    PubMed

    Qiu, Jichuan; Li, Jianhua; Wang, Shu; Ma, Baojin; Zhang, Shan; Guo, Weibo; Zhang, Xiaodi; Tang, Wei; Sang, Yuanhua; Liu, Hong

    2016-04-01

    As a physical cue for controlling the fate of stem cells, surface nanotopography has attracted much attention to improve the integration between implants and local host tissues and cells. A biocompatible surface TiO2 nanorod array is proposed to regulate the fate of bone marrow derived mesenchymal stem cells (MSCs). TiO2 substrates with different surface nanotopographies: a TiO2 nanorod array and a polished TiO2 ceramic are built by hydrothermal and sintering processes, respectively. The assessment of morphology, viability, gene expression, and protein characterization of the MSCs cultured on the different TiO2 substrates proves that a TiO2 nanorod array promotes the osteogenic differentiation of MSCs, while a TiO2 ceramic with a smooth surface suppresses it. Periodically assembled TiO2 nanorod array stripes on the smooth TiO2 ceramic are constructed by a combination of microfabrication and a chemical synthesis process, which realizes the location-committed osteogenic differentiation of MSCs. A route to control the differentiation of MSCs by a nanostructured surface, which can also control the location and direction of MSCs on the surface of biomaterials with micro-nano scale surface engineering, is demonstrated.

  20. Electron Injection from Copper Diimine Sensitizers into TiO2: Structural Effects and Their Implications for Solar Energy Conversion Devices.

    PubMed

    Mara, Michael W; Bowman, David N; Buyukcakir, Onur; Shelby, Megan L; Haldrup, Kristoffer; Huang, Jier; Harpham, Michael R; Stickrath, Andrew B; Zhang, Xiaoyi; Stoddart, J Fraser; Coskun, Ali; Jakubikova, Elena; Chen, Lin X

    2015-08-01

    Copper(I) diimine complexes have emerged as low cost replacements for ruthenium complexes as light sensitizers and electron donors, but their shorter metal-to-ligand-charge-transfer (MLCT) states lifetimes and lability of transient Cu(II) species impede their intended functions. Two carboxylated Cu(I) bis-2,9-diphenylphenanthroline (dpp) complexes [Cu(I)(dpp-O(CH2CH2O)5)(dpp-(COOH)2)](+) and [Cu(I)(dpp-O(CH2CH2O)5)(dpp-(Φ-COOH)2)](+) (Φ = tolyl) with different linker lengths were synthesized in which the MLCT-state solvent quenching pathways are effectively blocked, the lifetime of the singlet MLCT state is prolonged, and the transient Cu(II) ligands are stabilized. Aiming at understanding the mechanisms of structural influence to the interfacial charge transfer in the dye-sensitized solar cell mimics, electronic and geometric structures as well as dynamics for the MLCT state of these complexes and their hybrid with TiO2 nanoparticles were investigated using optical transient spectroscopy, X-ray transient absorption spectroscopy, time-dependent density functional theory, and quantum dynamics simulations. The combined results show that these complexes exhibit strong absorption throughout the visible spectrum due to the severely flattened ground state, and a long-lived charge-separated Cu(II) has been achieved via ultrafast electron injection (<300 fs) from the (1)MLCT state into TiO2 nanoparticles. The results also indicate that the TiO2-phen distance in these systems does not have significant effect on the efficiency of the interfacial electron-transfer process. The mechanisms for electron transfer in these systems are discussed and used to develop new strategies in optimizing copper(I) diimine complexes in solar energy conversion devices. PMID:26154849

  1. TiO2 nanoparticles induce DNA double strand breaks and cell cycle arrest in human alveolar cells.

    PubMed

    Kansara, Krupa; Patel, Pal; Shah, Darshini; Shukla, Ritesh K; Singh, Sanjay; Kumar, Ashutosh; Dhawan, Alok

    2015-03-01

    TiO2 nanoparticles (NPs) have the second highest global annual production (∼3000 tons) among the metal-containing NPs. These NPs are used as photocatalysts for bacterial disinfection, and in various other consumer products including sunscreen, food packaging, therapeutics, biosensors, surface cleaning agents, and others. Humans are exposed to these NPs during synthesis (laboratory), manufacture (industry), and use (consumer products, devices, medicines, etc.), as well as through environmental exposures (disposal). Hence, there is great concern regarding the health effects caused by exposure to NPs and, in particular, to TiO2 NPs. In the present study, the genotoxic potential of TiO2 NPs in A549 cells was examined, focusing on their potential to induce ROS, different types of DNA damage, and cell cycle arrest. We show that TiO2 NPs can induce DNA damage and a corresponding increase in micronucleus frequency, as evident from the comet and cytokinesis-block micronucleus assays. We demonstrate that DNA damage may be attributed to increased oxidative stress and ROS generation. Furthermore, genomic and proteomic analyses showed increased expression of ATM, P53, and CdC-2 and decreased expression of ATR, H2AX, and Cyclin B1 in A549 cells, suggesting induction of DNA double strand breaks. The occurrence of double strand breaks was correlated with cell cycle arrest in G2/M phase. Overall, the results indicate the potential for genotoxicity following exposure to these TiO2 NPs, suggesting that use should be carefully monitored.

  2. Reverse-engineering the atomic-scale structure of the TiO2/N3 interface in dye-sensitized solar cells using O1s core-level shifts

    NASA Astrophysics Data System (ADS)

    Patrick, Christopher; Giustino, Feliciano

    2011-03-01

    Dye-sensitized solar cells employing mesoporous titania films sensitized with ruthenium-based dyes have shown consistently good performance over the past two decades. Understanding the process of charge injection in these devices requires accurate atomistic models of the interface between the light-absorbing dye and the semiconducting substrate. Despite considerable efforts devoted to the experimental and theoretical investigation of such interfaces, their atomistic nature remains controversial. In this work we pursue a novel computational approach to the study of the semiconductor/dye interface which does not rely on the calculated adsorption energies. In our approach we reverse-engineer photoemission data through the first-principles calculation of O1s core-level spectra for a number of candidate interface models. Our calculations allow us to discard some of the adsorption geometries previously proposed and point to an interface model which reconciles conflicting assignments based either on photoemission or infrared data.

  3. Electrolyte Concentration Effect of a Photoelectrochemical Cell Consisting of TiO 2 Nanotube Anode

    DOE PAGES

    Ren, Kai; Gan, Yong X.; Nikolaidis, Efstratios; Sofyani, Sharaf Al; Zhang, Lihua

    2013-01-01

    The photoelectrochemical responses of a TiO 2 nanotube anode in ethylene glycol (EG), glycerol, ammonia, ethanol, urea, and Na 2 S electrolytes with different concentrations were investigated. The TiO 2 nanotube anode was highly efficient in photoelectrocatalysis in these solutions under UV light illumination. The photocurrent density is obviously affected by the concentration change. Na 2 S generated the highest photocurrent density at 0, 1, and 2 V bias voltages, but its concentration does not significantly affect the photocurrent density. Urea shows high open circuit voltage at proper concentration and low photocurrent at different concentrations. Externally applied bias voltage ismore » also an important factor that changes the photoelectrochemical reaction process. In view of the open circuit voltage, EG, ammonia, and ethanol fuel cells show the trend that the open circuit voltage (OCV) increases with the increase of the concentration of the solutions. Glycerol has the highest OCV compared with others, and it deceases with the increase in the concentration because of the high viscosity. The OCV of the urea and Na 2 S solutions did not show obvious concentration effect.« less

  4. Europium Doped TiO2 Hollow Nanoshells: Two-Photon Imaging of Cell Binding

    PubMed Central

    Sandoval, Sergio; Yang, Jian; Alfaro, Jesus G.; Liberman, Alexander; Makale, Milan; Chiang, Casey E.; Schuller, Ivan K.

    2012-01-01

    A simple scalable method to fabricate luminescent monodisperse 200 nm europium doped hollow TiO2 nanoshell particles is reported. Fluorophore reporter, Eu3+ ions, are incorporated directly in the NS matrix, leaving the surface free for functionalization and the core free for payload encapsulation. Amine functionalized polystyrene beads were used as templates, and the porous walls of europium doped titania nanoshells were synthesized using titanium(IV) t-butoxide and europium(III) nitrate as reactants. X-ray diffraction analysis identified anatase as the predominant titania phase of the rigid nanoshell wall structure, and photoluminescence spectra showed that the Eu(III) doped TiO2 nanoshells exhibited a red emission at 617 nm due to an atomic f-f transition. Nanoshell interactions with HeLa cervical cancer cells in vitro were visualized using two-photon microscopy of the Eu(III) emission, and studied using a luminescence ratio analysis to assess nanoshell adhesion and endocytosis. PMID:23185106

  5. Integration of CdSe/CdSexTe1-x Type-II Heterojunction Nanorods into Hierarchically Porous TiO2 Electrode for Efficient Solar Energy Conversion

    NASA Astrophysics Data System (ADS)

    Lee, Sangheon; Flanagan, Joseph C.; Kang, Joonhyeon; Kim, Jinhyun; Shim, Moonsub; Park, Byungwoo

    2015-12-01

    Semiconductor sensitized solar cells, a promising candidate for next-generation photovoltaics, have seen notable progress using 0-D quantum dots as light harvesting materials. Integration of higher-dimensional nanostructures and their multi-composition variants into sensitized solar cells is, however, still not fully investigated despite their unique features potentially beneficial for improving performance. Herein, CdSe/CdSexTe1-x type-II heterojunction nanorods are utilized as novel light harvesters for sensitized solar cells for the first time. The CdSe/CdSexTe1-x heterojunction-nanorod sensitized solar cell exhibits ~33% improvement in the power conversion efficiency compared to its single-component counterpart, resulting from superior optoelectronic properties of the type-II heterostructure and 1-octanethiol ligands aiding facile electron extraction at the heterojunction nanorod-TiO2 interface. Additional ~32% enhancement in power conversion efficiency is achieved by introducing percolation channels of large pores in the mesoporous TiO2 electrode, which allow 1-D sensitizers to infiltrate the entire depth of electrode. These strategies combined together lead to 3.02% power conversion efficiency, which is one of the highest values among sensitized solar cells utilizing 1-D nanostructures as sensitizer materials.

  6. Integration of CdSe/CdSexTe1-x Type-II Heterojunction Nanorods into Hierarchically Porous TiO2 Electrode for Efficient Solar Energy Conversion.

    PubMed

    Lee, Sangheon; Flanagan, Joseph C; Kang, Joonhyeon; Kim, Jinhyun; Shim, Moonsub; Park, Byungwoo

    2015-01-01

    Semiconductor sensitized solar cells, a promising candidate for next-generation photovoltaics, have seen notable progress using 0-D quantum dots as light harvesting materials. Integration of higher-dimensional nanostructures and their multi-composition variants into sensitized solar cells is, however, still not fully investigated despite their unique features potentially beneficial for improving performance. Herein, CdSe/CdSe(x)Te(1-x) type-II heterojunction nanorods are utilized as novel light harvesters for sensitized solar cells for the first time. The CdSe/CdSe(x)Te(1-x) heterojunction-nanorod sensitized solar cell exhibits ~33% improvement in the power conversion efficiency compared to its single-component counterpart, resulting from superior optoelectronic properties of the type-II heterostructure and 1-octanethiol ligands aiding facile electron extraction at the heterojunction nanorod-TiO(2) interface. Additional ~32% enhancement in power conversion efficiency is achieved by introducing percolation channels of large pores in the mesoporous TiO(2) electrode, which allow 1-D sensitizers to infiltrate the entire depth of electrode. These strategies combined together lead to 3.02% power conversion efficiency, which is one of the highest values among sensitized solar cells utilizing 1-D nanostructures as sensitizer materials. PMID:26638994

  7. Integration of CdSe/CdSexTe1-x Type-II Heterojunction Nanorods into Hierarchically Porous TiO2 Electrode for Efficient Solar Energy Conversion.

    PubMed

    Lee, Sangheon; Flanagan, Joseph C; Kang, Joonhyeon; Kim, Jinhyun; Shim, Moonsub; Park, Byungwoo

    2015-12-07

    Semiconductor sensitized solar cells, a promising candidate for next-generation photovoltaics, have seen notable progress using 0-D quantum dots as light harvesting materials. Integration of higher-dimensional nanostructures and their multi-composition variants into sensitized solar cells is, however, still not fully investigated despite their unique features potentially beneficial for improving performance. Herein, CdSe/CdSe(x)Te(1-x) type-II heterojunction nanorods are utilized as novel light harvesters for sensitized solar cells for the first time. The CdSe/CdSe(x)Te(1-x) heterojunction-nanorod sensitized solar cell exhibits ~33% improvement in the power conversion efficiency compared to its single-component counterpart, resulting from superior optoelectronic properties of the type-II heterostructure and 1-octanethiol ligands aiding facile electron extraction at the heterojunction nanorod-TiO(2) interface. Additional ~32% enhancement in power conversion efficiency is achieved by introducing percolation channels of large pores in the mesoporous TiO(2) electrode, which allow 1-D sensitizers to infiltrate the entire depth of electrode. These strategies combined together lead to 3.02% power conversion efficiency, which is one of the highest values among sensitized solar cells utilizing 1-D nanostructures as sensitizer materials.

  8. Semitransparent inverted polymer solar cells employing a sol-gel-derived TiO2 electron-selective layer on FTO and MoO3/Ag/MoO3 transparent electrode

    PubMed Central

    2014-01-01

    We report a new semitransparent inverted polymer solar cell (PSC) with a structure of glass/FTO/nc-TiO2/P3HT:PCBM/MoO3/Ag/MoO3. Because high-temperature annealing which decreased the conductivity of indium tin oxide (ITO) must be handled in the process of preparation of nanocrystalline titanium oxide (nc-TiO2), we replace glass/ITO with a glass/fluorine-doped tin oxide (FTO) substrate to improve the device performance. The experimental results show that the replacing FTO substrate enhances light transmittance between 400 and 600 nm and does not change sheet resistance after annealing treatment. The dependence of device performances on resistivity, light transmittance, and thickness of the MoO3/Ag/MoO3 film was investigated. High power conversion efficiency (PCE) was achieved for FTO substrate inverted PSCs, which showed about 75% increase compared to our previously reported ITO substrate device at different thicknesses of the MoO3/Ag/MoO3 transparent electrode films illuminated from the FTO side (bottom side) and about 150% increase illuminated from the MoO3/Ag/MoO3 side (top side). PMID:25332693

  9. Electrical Conductivity Characteristic of TiO2 Nanowires From Hydrothermal Method

    NASA Astrophysics Data System (ADS)

    Azlishah Othman, Mohd; Faridah Amat, Noor; Hisham Ahmad, Badrul; Rajan, Jose

    2014-04-01

    One dimensional nanostructures of titanium dioxide (TiO2) were synthesized via hydrothermal method by mixing TiO2 as precursor in aqueous solution of NaOH as solvent. Then, heat and washing treatment was applied. Thus obtained wires had diameter ~15nm. TiO2 nanowires will be used as a network in solar cell such dye-sensitized solar cell in order to improve the performance of electron movement in the device. To improve the performance of electron movement, the characteristics of TiO2 nanowires have been analyses using field emission scanning electron microscopy (FESEM) analysis, x-ray diffractometer (XRD) analysis and brunauer emmett teller (BET) analysis. Finally, electrical conductivity of TiO2 nanowires was determined by measuring the resistance of the TiO2 nanowires paste on microscope glass.

  10. Dye sensitized solar cells.

    PubMed

    Wei, Di

    2010-01-01

    Dye sensitized solar cell (DSSC) is the only solar cell that can offer both the flexibility and transparency. Its efficiency is comparable to amorphous silicon solar cells but with a much lower cost. This review not only covers the fundamentals of DSSC but also the related cutting-edge research and its development for industrial applications. Most recent research topics on DSSC, for example, applications of nanostructured TiO(2), ZnO electrodes, ionic liquid electrolytes, carbon nanotubes, graphene and solid state DSSC have all been included and discussed. PMID:20480003

  11. Dye Sensitized Solar Cells

    PubMed Central

    Wei, Di

    2010-01-01

    Dye sensitized solar cell (DSSC) is the only solar cell that can offer both the flexibility and transparency. Its efficiency is comparable to amorphous silicon solar cells but with a much lower cost. This review not only covers the fundamentals of DSSC but also the related cutting-edge research and its development for industrial applications. Most recent research topics on DSSC, for example, applications of nanostructured TiO2, ZnO electrodes, ionic liquid electrolytes, carbon nanotubes, graphene and solid state DSSC have all been included and discussed. PMID:20480003

  12. Nanoscale TiO2 nanotubes govern the biological behavior of human glioma and osteosarcoma cells.

    PubMed

    Tian, Ang; Qin, Xiaofei; Wu, Anhua; Zhang, Hangzhou; Xu, Quan; Xing, Deguang; Yang, He; Qiu, Bo; Xue, Xiangxin; Zhang, Dongyong; Dong, Chenbo

    2015-01-01

    Cells respond to their surroundings through an interactive adhesion process that has direct effects on cell proliferation and migration. This research was designed to investigate the effects of TiO2 nanotubes with different topographies and structures on the biological behavior of cultured cells. The results demonstrated that the nanotube diameter, rather than the crystalline structure of the coatings, was a major factor for the biological behavior of the cultured cells. The optimal diameter of the nanotubes was 20 nm for cell adhesion, migration, and proliferation in both glioma and osteosarcoma cells. The expression levels of vitronectin and phosphor-focal adhesion kinase were affected by the nanotube diameter; therefore, it is proposed that the responses of vitronectin and phosphor-focal adhesion kinase to the nanotube could modulate cell fate. In addition, the geometry and size of the nanotube coating could regulate the degree of expression of acetylated α-tubulin, thus indirectly modulating cell migration behavior. Moreover, the expression levels of apoptosis-associated proteins were influenced by the topography. In conclusion, a nanotube diameter of 20 nm was the critical threshold that upregulated the expression level of Bcl-2 and obviously decreased the expression levels of Bax and caspase-3. This information will be useful for future biomedical and clinical applications.

  13. Nanoscale TiO2 nanotubes govern the biological behavior of human glioma and osteosarcoma cells

    PubMed Central

    Tian, Ang; Qin, Xiaofei; Wu, Anhua; Zhang, Hangzhou; Xu, Quan; Xing, Deguang; Yang, He; Qiu, Bo; Xue, Xiangxin; Zhang, Dongyong; Dong, Chenbo

    2015-01-01

    Cells respond to their surroundings through an interactive adhesion process that has direct effects on cell proliferation and migration. This research was designed to investigate the effects of TiO2 nanotubes with different topographies and structures on the biological behavior of cultured cells. The results demonstrated that the nanotube diameter, rather than the crystalline structure of the coatings, was a major factor for the biological behavior of the cultured cells. The optimal diameter of the nanotubes was 20 nm for cell adhesion, migration, and proliferation in both glioma and osteosarcoma cells. The expression levels of vitronectin and phosphor-focal adhesion kinase were affected by the nanotube diameter; therefore, it is proposed that the responses of vitronectin and phosphor-focal adhesion kinase to the nanotube could modulate cell fate. In addition, the geometry and size of the nanotube coating could regulate the degree of expression of acetylated α-tubulin, thus indirectly modulating cell migration behavior. Moreover, the expression levels of apoptosis-associated proteins were influenced by the topography. In conclusion, a nanotube diameter of 20 nm was the critical threshold that upregulated the expression level of Bcl-2 and obviously decreased the expression levels of Bax and caspase-3. This information will be useful for future biomedical and clinical applications. PMID:25848261

  14. Hunting for the elusive shallow traps in TiO2 anatase.

    PubMed

    Antila, Liisa J; Santomauro, Fabio G; Hammarström, Leif; Fernandes, Daniel L A; Sá, Jacinto

    2015-07-11

    Understanding electron mobility on TiO2 is crucial because of its applications in photocatalysis and solar cells. This work shows that shallow traps believed to be involved in electron migration in TiO2 conduction band are formed upon band gap excitation, i.e., are not pre-existing states. The shallow traps in TiO2 results from large polarons and are not restricted to surface.

  15. Influence of TiO2 nanoparticles on cellular antioxidant defense and its involvement in genotoxicity in HepG2 cells

    NASA Astrophysics Data System (ADS)

    Petković, Jana; Žegura, Bojana; Filipič, Metka

    2011-07-01

    We investigated the effects of two types of TiO2 nanoparticles (<25 nm anatase, TiO2-An; <100 nm rutile, TiO2-Ru) on cellular antioxidant defense in HepG2 cells. We previously showed that in HepG2 cells, TiO2 nanoparticles are not toxic, although they induce oxidative DNA damage, production of intracellular reactive oxygen species, and up-regulation of mRNA expression of DNA-damage-responsive genes (p53, p21, gadd45α and mdm2). In the present study, we measured changes in mRNA expression of several antioxidant enzymes: catalase, superoxide dismutase, glutathione peroxidase, nitric oxide synthase, glutathione reductase and glutamate-cysteine ligase. As reduced glutathione has a central role in cellular antioxidant defense, we determined the effects of TiO2 nanoparticles on changes in the intracellular glutathione content. To confirm a role for glutathione in protection against TiO2-nanoparticle-induced DNA damage, we compared the extent of TiO2-nanoparticle-induced DNA damage in HepG2 cells that were glutathione depleted with buthionine-(S,R)-sulfoximine pretreatment and in nonglutathione-depleted cells. Our data show that both types of TiO2 nanoparticles up-regulate mRNA expression of oxidative-stress-related genes, with TiO2-Ru being a stronger inducer than TiO2-An. Both types of TiO2 nanoparticles also induce dose-dependent increases in intracellular glutathione levels, and in glutathione-depleted cells, TiO2-nanoparticle-induced DNA damage was significantly greater than in nonglutathione-depleted cells. Interestingly, the glutathione content and the extent of DNA damage were significantly higher in TiO2-An- than TiO2-Ru-exposed cells. Thus, we show that TiO2 nanoparticles cause activation of cellular antioxidant processes, and that intracellular glutathione has a critical role in defense against this TiO2-nanoparticle-induced DNA damage.

  16. Improved photoelectrical performance of graphene supported highly crystallized anatase TiO2

    NASA Astrophysics Data System (ADS)

    Zhang, Min; Sun, Qiong; Zhao, Mei; Li, Yang; Liu, Qiuhong; Dong, Lifeng

    2015-08-01

    In this study, titanium oxysulfate (TiOSO4) and graphene were used as titanium source and supporter, respectively, to synthesize anatase TiO2-graphene (TiO2-G) composite. Crystal structure, morphology, and composition of TiO2-G were investigated by X-ray diffraction, scanning electron microscope, transmission electron microscope, and thermogravimetric analysis. Both TiO2-G and blank TiO2 powders exhibit spindle-shaped structure with the long axis along [001]. Compared to unsupported TiO2, TiO2 nanoparticles uniformly formed on graphene surface. When fabricated into dye-sensitized solar cells, photoelectrical conversion efficiency of TiO2-G (2.3 %) was much higher than that of blank TiO2 (0.89 %) prepared at the same conditions. Moreover, high sintering temperature enhanced photoelectrical performance of the composite. When the temperature was increased from 450 to 600 °C, the efficiency was improved from 1.5 to 2.6 %. The findings above demonstrate that TiO2-G has great potential for applications in dye-sensitized solar cells.

  17. Solar Spectrum Photocatalytic Conversion of CO2 and Water Vapor Into Hydrocarbons Using TiO2 Nanoparticle Membranes

    NASA Astrophysics Data System (ADS)

    Rani, Sanju; Bao, Ningzhong; Roy, Somnath C.

    2014-01-01

    A viable option for recycling carbon dioxide is through the sunlight-powered photocatalytic conversion of CO2 and water vapor into hydrocarbon fuels over highly active nanocatalysts. With photocatalytic CO2 reduction sunlight, a renewable energy source as durable as the sun, is used to drive the catalytic reaction with the resultant fuel products compatible with the current hydrocarbon-based energy infrastructure. The use of co-catalyst (Cu, Pt)-sensitized TiO2 nanoparticle wafers in the photocatalytic conversion of CO2 and water vapor to hydrocarbon fuels, with optimal humidity levels and exposure times established. We also attempted to increase product formation by sputtering both co-catalysts on the nanoparticle wafer's surface, with the resulting product rates significantly higher than that of either the Cu or Pt coated samples. When the TiO2 nanoparticle wafers are used in a flow-through membrane implementation we find a significant increase in product rates of formation, including methane, hydrogen, and carbon monoxide. We believe that nanocatalyst-based flow-through membranes are a viable route for achieving large-scale and low cost photocatalytic solar fuel production.

  18. Photocatalytic performance of nitrogen, osmium co-doped TiO2 for removal of eosin yellow in water under simulated solar radiation.

    PubMed

    Kuvarega, Alex T; Krause, Rui W M; Mamba, Bhekie B

    2013-07-01

    Nitrogen, osmium co-doped TiO2 photocatalysts were prepared by a modified sol-gel method using ammonia as the nitrogen source and osmium tetroxide as the source of osmium. The role of rutile phase OsO2 in enhancing the photocatalytic activity of rutile TiO2 towards the degradation of Eosin Yellow was investigated. The materials were characterised by various techniques that include FTIR, Raman, XRD, SEM, EDS, TEM, TGA and DRUV-Vis. The amorphous, oven dried sample was transformed to the anatase and then the rutile phase with increasing calcination temperature. DRUV-Vis analysis revealed a red shift in absorption with increasing calcination temperature, confirmed by a decrease in the band gap of the material. The photocatalytic activity of N, Os co-doped TiO2 was evaluated using eosin yellow degradation and activity increased with increase in calcination temperature under simulated solar irradiation. The rutile phase of the co-doped TiO2 was found to be more effective in degrading the dye (k(a) = 1.84 x 10(-2) min(-1)) compared to the anatase co-doped phase (k(a) = 9.90 x 10(-3) min(-1)). The enhanced photocatalytic activity was ascribed to the synergistic effects of rutile TiO2 and rutile OsO2 in the N, Os co-doped TiO2. PMID:23901525

  19. Photocatalytic performance of nitrogen, osmium co-doped TiO2 for removal of eosin yellow in water under simulated solar radiation.

    PubMed

    Kuvarega, Alex T; Krause, Rui W M; Mamba, Bhekie B

    2013-07-01

    Nitrogen, osmium co-doped TiO2 photocatalysts were prepared by a modified sol-gel method using ammonia as the nitrogen source and osmium tetroxide as the source of osmium. The role of rutile phase OsO2 in enhancing the photocatalytic activity of rutile TiO2 towards the degradation of Eosin Yellow was investigated. The materials were characterised by various techniques that include FTIR, Raman, XRD, SEM, EDS, TEM, TGA and DRUV-Vis. The amorphous, oven dried sample was transformed to the anatase and then the rutile phase with increasing calcination temperature. DRUV-Vis analysis revealed a red shift in absorption with increasing calcination temperature, confirmed by a decrease in the band gap of the material. The photocatalytic activity of N, Os co-doped TiO2 was evaluated using eosin yellow degradation and activity increased with increase in calcination temperature under simulated solar irradiation. The rutile phase of the co-doped TiO2 was found to be more effective in degrading the dye (k(a) = 1.84 x 10(-2) min(-1)) compared to the anatase co-doped phase (k(a) = 9.90 x 10(-3) min(-1)). The enhanced photocatalytic activity was ascribed to the synergistic effects of rutile TiO2 and rutile OsO2 in the N, Os co-doped TiO2.

  20. Anodization parameters influencing the morphology and electrical properties of TiO2 nanotubes for living cell interfacing and investigations.

    PubMed

    Khudhair, D; Bhatti, A; Li, Y; Hamedani, H Amani; Garmestani, H; Hodgson, P; Nahavandi, S

    2016-02-01

    Nanotube structures have attracted tremendous attention in recent years in many applications. Among such nanotube structures, titania nanotubes (TiO2) have received paramount attention in the medical domain due to their unique properties, represented by high corrosion resistance, good mechanical properties, high specific surface area, as well as great cell proliferation, adhesion and mineralization. Although lot of research has been reported in developing optimized titanium nanotube structures for different medical applications, however there is a lack of unified literature source that could provide information about the key parameters and experimental conditions required to develop such optimized structure. This paper addresses this gap, by focussing on the fabrication of TiO2 nanotubes through anodization process on both pure titanium and titanium alloys substrates to exploit the biocompatibility and electrical conductivity aspects, critical factors for many medical applications from implants to in-vivo and in-vitro living cell studies. It is shown that the morphology of TiO2 directly impacts the biocompatibility aspects of the titanium in terms of cell proliferation, adhesion and mineralization. Similarly, TiO2 nanotube wall thickness of 30-40nm has shown to exhibit improved electrical behaviour, a critical factor in brain mapping and behaviour investigations if such nanotubes are employed as micro-nano-electrodes.

  1. Nanostructured N-doped TiO2 marigold flowers for an efficient solar hydrogen production from H2S

    NASA Astrophysics Data System (ADS)

    Chaudhari, Nilima S.; Warule, Sambhaji S.; Dhanmane, Sushil A.; Kulkarni, Milind V.; Valant, Matjaz; Kale, Bharat B.

    2013-09-01

    Nitrogen-doped TiO2 nanostructures in the form of marigold flowers have been synthesized for the first time using a facile solvothermal method. The structural analysis has shown that such an N-doped TiO2 system crystallizes in the anatase structure. The optical absorption spectra have clearly shown the shift in the absorption edge towards the visible-light range, which indicates successful nitrogen doping. The nitrogen doping has been further confirmed by photoluminescence and photoemission spectroscopy. Microscopy studies have shown the thin nanosheets (petals) of N-TiO2 with a thickness of ~2-3 nm, assembled in the form of the marigold flower with a high surface area (224 m2 g-1). The N-TiO2 nanostructure with marigold flowers is an efficient photocatalyst for the decomposition of H2S and production of hydrogen under solar light. The maximum hydrogen evolution obtained is higher than other known N-TiO2 systems. It is noteworthy that photohydrogen production using the unique marigold flowers of N-TiO2 from abundant H2S under solar light is hitherto unattempted. The proposed synthesis method can also be utilized to design other hierarchical nanostructured N-doped metal oxides.Nitrogen-doped TiO2 nanostructures in the form of marigold flowers have been synthesized for the first time using a facile solvothermal method. The structural analysis has shown that such an N-doped TiO2 system crystallizes in the anatase structure. The optical absorption spectra have clearly shown the shift in the absorption edge towards the visible-light range, which indicates successful nitrogen doping. The nitrogen doping has been further confirmed by photoluminescence and photoemission spectroscopy. Microscopy studies have shown the thin nanosheets (petals) of N-TiO2 with a thickness of ~2-3 nm, assembled in the form of the marigold flower with a high surface area (224 m2 g-1). The N-TiO2 nanostructure with marigold flowers is an efficient photocatalyst for the decomposition of H2S and

  2. Synthesis of activated charcoal supported Bi-doped TiO2 nanocomposite under solar light irradiation for enhanced photocatalytic activity

    NASA Astrophysics Data System (ADS)

    Chandraboss, V. L.; Kamalakkannan, J.; Senthilvelan, S.

    2016-11-01

    In this study, activated charcoal (AC) supported bismuth (Bi)-doped Titanium dioxide (TiO2) nanocomposite was synthesized by precipitation method. The photocatalytic activity of AC-Bi/TiO2 was investigated for the degradation of methylene blue (MB) in aqueous solution under solar light irradiation. The incorporation of Bi3+ into the TiO2 lattice shifts the absorbance of TiO2 to the visible region then the addition of high adsorption capacity activated charcoal to improve the efficiency of TiO2. AC-Bi/TiO2 is found to be more efficient than Bi/TiO2 and undoped TiO2 for the degradation of MB under solar light irradiation. Surface morphology and bulk composition of the composite was obtained using high resolution-scanning electron microscopy with energy dispersive X-ray analysis. The crystal structure evolution and elemental composition were analyzed by combining Fourier transform-Raman spectroscopy, X-ray diffraction and X-ray photoelectron spectroscopy. The ultraviolet-visible (UV-vis) absorption spectra show that the absorption edge for the composite with Bi3+ has red shift as compared with that of undoped TiO2. UV-vis diffuse reflectance spectra demonstrated a decrease in the direct band gap of AC-Bi/TiO2. BET surface area, pore radius and pore volume of the materials were calculated by applying the BET equation to the sorption isotherms. The production of hydroxyl radicals (rad OH) on the surface of solar light irradiated materialswere detected by photoluminescence technique using coumarin as a probe molecule. The mechanism of photocatalytic effect of the AC-Bi/TiO2 was proposed for the degradation of MB under solar light irradiation.

  3. Biochemical effects of six TiO2 and four CeO2 nanomaterials in HepG2 cells

    EPA Science Inventory

    Biochemical effects of six TiO2 and four CeO2 nanomaterials in HepG2 cellsBecause of their growing number of uses, nanoparticles composed of CeO2 (cosmetics, polishing materials and automotive fuel additives) and TiO2 (pigments, sunscreens and photocatalysts) are of particular to...

  4. Ti3+-self doped brookite TiO2 single-crystalline nanosheets with high solar absorption and excellent photocatalytic CO2 reduction

    NASA Astrophysics Data System (ADS)

    Xin, Xiaoye; Xu, Tao; Wang, Lan; Wang, Chuanyi

    2016-03-01

    Black brookite TiO2 single-crystalline nanosheets with outstanding photocatalytic activity toward CO2 reduction is prepared by a facile oxidation-based hydrothermal reaction method combined with post-annealing treatment. Large amount of Ti3+ defects are introduced into the bulk of brookite nanoparticles, which increases the solar energy absorption and enhances the photocatalytic activity.

  5. Ti3+-self doped brookite TiO2 single-crystalline nanosheets with high solar absorption and excellent photocatalytic CO2 reduction

    PubMed Central

    Xin, Xiaoye; Xu, Tao; Wang, Lan; Wang, Chuanyi

    2016-01-01

    Black brookite TiO2 single-crystalline nanosheets with outstanding photocatalytic activity toward CO2 reduction is prepared by a facile oxidation-based hydrothermal reaction method combined with post-annealing treatment. Large amount of Ti3+ defects are introduced into the bulk of brookite nanoparticles, which increases the solar energy absorption and enhances the photocatalytic activity. PMID:27021203

  6. Synthesis of TiO2 nanotubes with ZnO nanoparticles to achieve antibacterial properties and stem cell compatibility.

    PubMed

    Liu, Wenwen; Su, Penglei; Chen, Su; Wang, Na; Ma, Yuanping; Liu, Yiran; Wang, Jinshu; Zhang, Zhenting; Li, Hongyi; Webster, Thomas J

    2014-08-01

    To endow titanium (Ti) with antibacterial properties, different concentrations of zinc oxide (ZnO) nanoparticles were decorated on anodized titanium dioxide (TiO2) nanotubes by a simple hydrothermal treatment method. The particle sizes of ZnO, which were evenly distributed and tightly adherent to the walls of the Ti nanotubes, ranged from 20-50 nm. Results from this study showed that Zn was released from the TiO2 nanotubes in a constant, slow, and biologically inspired manner. Importantly, the results showed that the ZnO decorated TiO2 nanotubular samples inhibited Streptococcus mutants and Porphyromonas gingivalis growth compared to control unmodified Ti samples. Specifically, S. mutants and P. gingivalis growth were both reduced 45-85% on the ZnO decorated Ti samples compared to Ti controls after 7 days of culture. When examining the mechanism of action, it has been further found for the first time that the ZnO decorated Ti samples inhibited the expression of Streptococcus mutans bacterial adhesion genes. Lastly, the results showed that the same samples which decreased bacterial growth the most (0.015 M precursor Zn(NO3)2 samples) did not inhibit mesenchymal stem cell growth compared to Ti controls for up to 7 days. In summary, results from this study showed that compared to plain TiO2 nanotubes, TiO2 decorated with 0.015 M ZnO provided unprecedented antibacterial properties while maintaining the stem cell proliferation capacity necessary for enhancing the use of Ti in numerous medical applications, particularly in dentistry. PMID:24971593

  7. Synthesis of TiO2 nanotubes with ZnO nanoparticles to achieve antibacterial properties and stem cell compatibility

    NASA Astrophysics Data System (ADS)

    Liu, Wenwen; Su, Penglei; Chen, Su; Wang, Na; Ma, Yuanping; Liu, Yiran; Wang, Jinshu; Zhang, Zhenting; Li, Hongyi; Webster, Thomas J.

    2014-07-01

    To endow titanium (Ti) with antibacterial properties, different concentrations of zinc oxide (ZnO) nanoparticles were decorated on anodized titanium dioxide (TiO2) nanotubes by a simple hydrothermal treatment method. The particle sizes of ZnO, which were evenly distributed and tightly adherent to the walls of the Ti nanotubes, ranged from 20-50 nm. Results from this study showed that Zn was released from the TiO2 nanotubes in a constant, slow, and biologically inspired manner. Importantly, the results showed that the ZnO decorated TiO2 nanotubular samples inhibited Streptococcus mutants and Porphyromonas gingivalis growth compared to control unmodified Ti samples. Specifically, S. mutants and P. gingivalis growth were both reduced 45-85% on the ZnO decorated Ti samples compared to Ti controls after 7 days of culture. When examining the mechanism of action, it has been further found for the first time that the ZnO decorated Ti samples inhibited the expression of Streptococcus mutans bacterial adhesion genes. Lastly, the results showed that the same samples which decreased bacterial growth the most (0.015 M precursor Zn(NO3)2 samples) did not inhibit mesenchymal stem cell growth compared to Ti controls for up to 7 days. In summary, results from this study showed that compared to plain TiO2 nanotubes, TiO2 decorated with 0.015 M ZnO provided unprecedented antibacterial properties while maintaining the stem cell proliferation capacity necessary for enhancing the use of Ti in numerous medical applications, particularly in dentistry.

  8. Comparison of photocatalytic properties of TiO2 thin films and fibers

    NASA Astrophysics Data System (ADS)

    Ozdemir, Mehtap; Kurt, Metin; Ozyuzer, Lutfi; Aygun, Gulnur

    2016-10-01

    Efficiency of solar panels degrades as a result of organic contamination such as airborne particles, bird droppings and leaves. Any foreign object on photovoltaic panels reduces the sunlight entering the absorbing surface of the solar panels. Since this leads to a major problem decreasing in energy production, solar panels should be cleaned. The self-cleaning method can be preferred. There are some methods to clean the surface of solar panels. Among the self-cleaning materials, TiO2 is the most preferable ones because of its powerful photocatalytic properties. In this study, photocatalytic TiO2 were produced in two different nanostructures: nanofibers and thin films. TiO2 nanofibers were successfully produced by electrospinning. TiO2 thin films were fabricated by reactive magnetron sputtering technique. Both TiO2 nanofiber and thin film structures were heat-treated to form TiO2 in anatase phase at 600 °C for 2 h in air. Then, they were evaluated by SEM analyses for morphology, X-ray diffraction (XRD) analyses for phase structures, X-ray photoelectron spectroscopy (XPS) for the chemical state and atomic concentration, and UV-spectrometer for photocatalytic performance. The results indicate that photocatalytic and transmittance properties of TiO2 thin films are better than those of nanofibers. Consequently, TiO2 based thin films exhibit better performance for solar cell applications due to the surface cleanliness.

  9. Surface Treatment for Effective Dye Adsorption on Nanocrystalline TiO2

    NASA Astrophysics Data System (ADS)

    Yanagida, Masatoshi; Han, Chen; Han, Liyuan

    2012-10-01

    To improve the efficiency of dye-sensitized solar cells (DSCs) by controlling dye adsorption on TiO2 surface, the effect of surface treatments on the properties of [NBu4]2[Ru(Htcterpy)(NCS)3] (black dye; [NBu4]: tetrabutylammonium cation; H3tcterpy: 4,4',4''-tricarboxy-2,2':6',2''-terpyridine) on nanocrystalline TiO2 films was investigated by analysis of the photovoltaic performance and the electron transport properties. Although the surface treatments do not affect on the condition band edge of TiO2, the amount of dye on TiO2 increases. The enhancement of dye adsorption by treatment of TiO2 in HCl solution is more effective than that by dipping the dye solution containing deoxycholic acid (DCA) as additive. But the charge recombination between an electron in TiO2 and I3- in the electrolyte can be reduced by the DCA treatment.

  10. TiO2/bi A-SPAES(Ds 1.0) composite membranes for proton exchange membrane in direct methanol fuel cell (DMFC).

    PubMed

    Zhang, Ni; Zhong, Chuanqing; Xie, Bing; Liu, Huiling; Wang, Xingzu

    2014-09-01

    A series of TiO2/bi A-SPAES(Ds 1.0) composite membranes with various contents of nano-sized TiO2 particles were prepared through sol-gel method. Scanning electron microscopy (SEM) images indicated the TiO2 particles were well dispersed within polymer matrix. These membranes were used for proton exchange membrane (PEM) for performance evaluation in direct methanol fuel cell (DMFC). These composite membranes showed good thermal stability and mechanical strength. It was found that the water uptake of these membranes enhanced with the TiO2 amount increasing in these composite membranes. Meanwhile, the introduction of TiO2 particles increased the proton conductivity and reduced the methanol permeability. The proton conductivities of these composite membranes with 8% TiO2 particles (0.120 S/cm and 0.128 S/cm) were higher than those of Nafion 117 membrane (0.114 S/cm and 0.117 S/cm) at 80 degrees C and 100 degrees C. Specially, the methanol diffusion coefficient (1.2 x 10(-7) cm2/s) of the composite membrane with 8% TiO2 content was much lower than that of Nafion 117 membrane (2.1 x 10(-6) cm2/s). As a result, the TiO2/bi A-SPAES composite membrane was considered as a promising material for PEM in DMFC.

  11. Enhanced in vitro angiogenic behaviour of human umbilical vein endothelial cells on thermally oxidized TiO2 nanofibrous surfaces

    NASA Astrophysics Data System (ADS)

    Tan, Ai Wen; Liau, Ling Ling; Chua, Kien Hui; Ahmad, Roslina; Akbar, Sheikh Ali; Pingguan-Murphy, Belinda

    2016-02-01

    One of the major challenges in bone grafting is the lack of sufficient bone vascularization. A rapid and stable bone vascularization at an early stage of implantation is essential for optimal functioning of the bone graft. To address this, the ability of in situ TiO2 nanofibrous surfaces fabricated via thermal oxidation method to enhance the angiogenic potential of human umbilical vein endothelial cells (HUVECs) was investigated. The cellular responses of HUVECs on TiO2 nanofibrous surfaces were studied through cell adhesion, cell proliferation, capillary-like tube formation, growth factors secretion (VEGF and BFGF), and angiogenic-endogenic-associated gene (VEGF, VEGFR2, BFGF, PGF, HGF, Ang-1, VWF, PECAM-1 and ENOS) expression analysis after 2 weeks of cell seeding. Our results show that TiO2 nanofibrous surfaces significantly enhanced adhesion, proliferation, formation of capillary-like tube networks and growth factors secretion of HUVECs, as well as leading to higher expression level of all angiogenic-endogenic-associated genes, in comparison to unmodified control surfaces. These beneficial effects suggest the potential use of such surface nanostructures to be utilized as an advantageous interface for bone grafts as they can promote angiogenesis, which improves bone vascularization.

  12. Enhanced in vitro angiogenic behaviour of human umbilical vein endothelial cells on thermally oxidized TiO2 nanofibrous surfaces

    PubMed Central

    Tan, Ai Wen; Liau, Ling Ling; Chua, Kien Hui; Ahmad, Roslina; Akbar, Sheikh Ali; Pingguan-Murphy, Belinda

    2016-01-01

    One of the major challenges in bone grafting is the lack of sufficient bone vascularization. A rapid and stable bone vascularization at an early stage of implantation is essential for optimal functioning of the bone graft. To address this, the ability of in situ TiO2 nanofibrous surfaces fabricated via thermal oxidation method to enhance the angiogenic potential of human umbilical vein endothelial cells (HUVECs) was investigated. The cellular responses of HUVECs on TiO2 nanofibrous surfaces were studied through cell adhesion, cell proliferation, capillary-like tube formation, growth factors secretion (VEGF and BFGF), and angiogenic-endogenic-associated gene (VEGF, VEGFR2, BFGF, PGF, HGF, Ang-1, VWF, PECAM-1 and ENOS) expression analysis after 2 weeks of cell seeding. Our results show that TiO2 nanofibrous surfaces significantly enhanced adhesion, proliferation, formation of capillary-like tube networks and growth factors secretion of HUVECs, as well as leading to higher expression level of all angiogenic-endogenic-associated genes, in comparison to unmodified control surfaces. These beneficial effects suggest the potential use of such surface nanostructures to be utilized as an advantageous interface for bone grafts as they can promote angiogenesis, which improves bone vascularization. PMID:26883761

  13. Enhanced in vitro angiogenic behaviour of human umbilical vein endothelial cells on thermally oxidized TiO2 nanofibrous surfaces.

    PubMed

    Tan, Ai Wen; Liau, Ling Ling; Chua, Kien Hui; Ahmad, Roslina; Akbar, Sheikh Ali; Pingguan-Murphy, Belinda

    2016-01-01

    One of the major challenges in bone grafting is the lack of sufficient bone vascularization. A rapid and stable bone vascularization at an early stage of implantation is essential for optimal functioning of the bone graft. To address this, the ability of in situ TiO2 nanofibrous surfaces fabricated via thermal oxidation method to enhance the angiogenic potential of human umbilical vein endothelial cells (HUVECs) was investigated. The cellular responses of HUVECs on TiO2 nanofibrous surfaces were studied through cell adhesion, cell proliferation, capillary-like tube formation, growth factors secretion (VEGF and BFGF), and angiogenic-endogenic-associated gene (VEGF, VEGFR2, BFGF, PGF, HGF, Ang-1, VWF, PECAM-1 and ENOS) expression analysis after 2 weeks of cell seeding. Our results show that TiO2 nanofibrous surfaces significantly enhanced adhesion, proliferation, formation of capillary-like tube networks and growth factors secretion of HUVECs, as well as leading to higher expression level of all angiogenic-endogenic-associated genes, in comparison to unmodified control surfaces. These beneficial effects suggest the potential use of such surface nanostructures to be utilized as an advantageous interface for bone grafts as they can promote angiogenesis, which improves bone vascularization. PMID:26883761

  14. Effect of TiO2 nanoparticles on adipose derived stromal cell differentiation, morphology, ECM deposition and its susceptibility to bacterial infections

    NASA Astrophysics Data System (ADS)

    Mironava, Tatsiana; Xu, Yan; Rafailovich, Miriam

    The growing annual production of Titanium dioxide (TiO2) nanoparticles is proportional to an increase in the chances of occupational and consumer exposure. Considering, that these nanoparticles are currently being used in multiple personal care products many concerns have arisen about their health impact. Human skin is in constant contact with the external environment and is one of the most important routes of exposure to TiO2. In this study we have investigated the effect of two forms of TiO2, rutile and anatase, on human adipose derived stromal cells (ADSCs). Here, we focus on the effects of TiO2 exposure on intracellular lipid accumulation and expression of adipogenic markers; on whether different forms of TiO2 have similar effects on cell function; and whether nanoparticle localization inside cells correlates with loss of cell function. In addition presence of bacteria on the skin is taken into account in its complex interaction with ADSCs and TiO2 nanoparticles. Altogether, the present study indicates that nanosized TiO2 particles adversely effects the differentiation of ADSCs, have profound effects on cell function and increase the rate of bacterial infection.

  15. The Effects of TiO2 Nanodot Films with RGD Immobilization on Light-Induced Cell Sheet Technology

    PubMed Central

    Yu, Meng-Liu; Yu, Meng-Fei; Zhu, Li-Qin; Wang, Tian-Tian; Zhou, Yi; Wang, Hui-Ming

    2015-01-01

    Cell sheet technology is a new strategy in tissue engineering which could be possible to implant into the body without a scaffold. In order to get an integrated cell sheet, a light-induced method via UV365 is used for cell sheet detachment from culture dishes. In this study, we investigated the possibility of cell detachment and growth efficiency on TiO2 nanodot films with RGD immobilization on light-induced cell sheet technology. Mouse calvaria-derived, preosteoblastic (MC3T3-E1) cells were cultured on TiO2 nanodot films with (TR) or without (TN) RGD immobilization. After cells were cultured with or without 5.5 mW/cm2 UV365 illumination, cell morphology, cell viability, osteogenesis related RNA and protein expression, and cell detachment ability were compared, respectively. Light-induced cell detachment was possible when cells were cultured on TR samples. Also, cells cultured on TR samples showed better cell viability, alongside higher protein and RNA expression than on TN samples. This study provides a new biomaterial for light-induced cell/cell sheet harvesting. PMID:26417596

  16. The detrimental influence of bacteria (E. coli, Shigella and Salmonella) on the degradation of organic compounds (and vice versa) in TiO2 photocatalysis and near-neutral photo-Fenton processes under simulated solar light.

    PubMed

    Moncayo-Lasso, Alejandro; Mora-Arismendi, Luis Enrique; Rengifo-Herrera, Julián Andrés; Sanabria, Janeth; Benítez, Norberto; Pulgarin, César

    2012-05-01

    TiO2 photocatalytic and near-neutral photo-Fenton processes were tested under simulated solar light to degrade two models of natural organic matter - resorcinol (R) (which should interact strongly with TiO2 surfaces) and hydroquinone (H) - separately or in the presence of bacteria. Under similar oxidative conditions, inactivation of Escherichia coli, Shigella sonnei and Salmonella typhimurium was carried out in the absence and in the presence of 10 mg L(-1) of R and H. The 100% abatement of R and H by using a TiO2 photocatalytic process in the absence of bacteria was observed in 90 min for R and in 120 min for H, while in the presence of microorganisms abatement was only of 55% and 35% for R and H, respectively. Photo-Fenton reagent at pH 5.0 completely removed R and H in 40 min, whereas in the presence of microorganisms their degradation was of 60% to 80%. On the other hand, 2 h of TiO2 photocatalytic process inactivated S. typhimurium and E. coli cells in three and six orders of magnitude, respectively, while S. sonnei was completely inactivated in 10 min. In the presence of R or H, the bacterial inactivation via TiO2 photocatalysis was significantly decreased. With photo-Fenton reagent at pH 5 all the microorganisms tested were completely inactivated in 40 min of simulated solar light irradiation in the absence of organics. When R and H were present, bacterial photo-Fenton inactivation was less affected. The obtained results suggest that in both TiO2 and iron photo-assisted processes, there is competition between organic substances and bacteria simultaneously present for generated reactive oxygen species (ROS). This competition is most important in heterogeneous systems, mainly when there are strong organic-TiO2 surface interactions, as in the resorcinol case, suggesting that bacteria-TiO2 interactions could play a key role in photocatalytic cell inactivation processes. PMID:22370626

  17. A Brown Mesoporous TiO2-x /MCF Composite with an Extremely High Quantum Yield of Solar Energy Photocatalysis for H2 Evolution.

    PubMed

    Xing, Mingyang; Zhang, Jinlong; Qiu, Bocheng; Tian, Baozhu; Anpo, Masakazu; Che, Michel

    2015-04-24

    A brown mesoporous TiO2-x /MCF composite with a high fluorine dopant concentration (8.01 at%) is synthesized by a vacuum activation method. It exhibits an excellent solar absorption and a record-breaking quantum yield (Φ = 46%) and a high photon-hydrogen energy conversion efficiency (η = 34%,) for solar photocatalytic H2 production, which are all higher than that of the black hydrogen-doped TiO2 (Φ = 35%, η = 24%). The MCFs serve to improve the adsorption of F atoms onto the TiO2 /MCF composite surface, which after the formation of oxygen vacancies by vacuum activation, facilitate the abundant substitution of these vacancies with F atoms. The decrease of recombination sites induced by high-concentration F doping and the synergistic effect between lattice Ti(3+)-F and surface Ti(3+)-F are responsible for the enhanced lifetime of electrons, the observed excellent absorption of solar light, and the photocatalytic production of H2 for these catalysts. The as-prepared F-doped composite is an ideal solar light-driven photocatalyst with great potential for applications ranging from the remediation of environmental pollution to the harnessing of solar energy for H2 production.

  18. Cyto- and genotoxicity of ultrafine TiO2 particles in cultured human lymphoblastoid cells.

    PubMed

    Wang, Jing J; Sanderson, Barbara J S; Wang, He

    2007-04-01

    Titanium dioxide is frequently used in the production of paints, paper, plastics, welding rod-coating material, and cosmetics, because of its low toxicity. However, recent studies have shown that nano-sized or ultrafine TiO(2) (UF-TiO(2)) (<100 nm in diameter) can generate pulmonary fibrosis and lung tumor in rats. Cytotoxicity induced by UF-TiO(2) in rat lung alveolar macrophages was also observed. This generates great concern about the possible adverse effects of UF-TiO(2) for humans. The cytotoxicity and genotoxicity of UF-TiO(2) were investigated using the methyl tetrazolium cytotoxicity (MTT) assay, the population growth assay, the apoptosis assay by flow cytometry, the cytokinesis block micronucleus (CBMN) assay, the comet assay, and the hypoxanthine-guanine phosphoribosyltransferase (HPRT) gene mutation assay. WIL2-NS cells were incubated for 6, 24 and 48 h with 0, 26, 65 and 130 microg/ml UF-TiO(2). Significant decreases in viability were seen in the MTT assay at higher doses; for example, 61, 7 and 2% relative viability at 130 microg/ml for 6, 24 and 48-h exposure (P<0.01). A dose-dependent relationship was observed, while a time-dependent relationship was seen only at the highest dose (130 microg/ml) after exposure for 24 and 48 h. Treatment with 130 microg/ml UF-TiO(2) induced approximately 2.5-fold increases in the frequency of micronucleated binucleated cells (P<0.01). In addition, a significant reduction in the cytokinesis block proliferation index was observed by the CBMN assay (P<0.05). In the comet assay, treatment with 65 microg/ml UF-TiO(2) induced approximately 5-fold increases in olive tail moment (P<0.05). In the HPRT mutation assay, treatment with 130 microg/ml UF-TiO(2) induced approximately 2.5-fold increases in the mutation frequency (P<0.05). The results of this study indicate that UF-TiO(2) can cause genotoxicity and cytotoxicity in cultured human cells.

  19. Development of solar-driven electrochemical and photocatalytic water treatment system using a boron-doped diamond electrode and TiO2 photocatalyst.

    PubMed

    Ochiai, Tsuyoshi; Nakata, Kazuya; Murakami, Taketoshi; Fujishima, Akira; Yao, Yanyan; Tryk, Donald A; Kubota, Yoshinobu

    2010-02-01

    A high-performance, environmentally friendly water treatment system was developed. The system consists mainly of an electrochemical and a photocatalytic oxidation unit, with a boron-doped diamond (BDD) electrode and TiO(2) photocatalyst, respectively. All electric power for the mechanical systems and the electrolysis was able to be provided by photovoltaic cells. Thus, this system is totally driven by solar energy. The treatment ability of the electrolysis and photocatalysis units was investigated by phenol degradation kinetics. An observed rate constant of 5.1 x 10(-3)dm(3)cm(-2)h(-1) was calculated by pseudo-first-order kinetic analysis for the electrolysis, and a Langmuir-Hinshelwood rate constant of 5.6 microM(-1)min(-1) was calculated by kinetic analysis of the photocatalysis. According to previous reports, these values are sufficient for the mineralization of phenol. In a treatment test of river water samples, large amounts of chemical and biological contaminants were totally wet-incinerated by the system. This system could provide 12L/day of drinking water from the Tama River using only solar energy. Therefore, this system may be useful for supplying drinking water during a disaster.

  20. Role of Zn doping in oxidative stress mediated cytotoxicity of TiO2 nanoparticles in human breast cancer MCF-7 cells

    PubMed Central

    Ahamed, Maqusood; Khan, M. A. Majeed; Akhtar, Mohd Javed; Alhadlaq, Hisham A.; Alshamsan, Aws

    2016-01-01

    We investigated the effect of Zn-doping on structural and optical properties as well as cellular response of TiO2 nanoparticles (NPs) in human breast cancer MCF-7 cells. A library of Zn-doped (1–10 at wt%) TiO2 NPs was prepared. Characterization data indicated that dopant Zn was incorporated into the lattice of host TiO2. The average particle size of TiO2 NPs was decreases (38 to 28 nm) while the band gap energy was increases (3.35 eV–3.85 eV) with increasing the amount of Zn-doping. Cellular data demonstrated that Zn-doped TiO2 NPs induced cytotoxicity (cell viability reduction, membrane damage and cell cycle arrest) and oxidative stress (reactive oxygen species generation & glutathione depletion) in MCF-7 cells and toxic intensity was increases with increasing the concentration of Zn-doping. Molecular data revealed that Zn-doped TiO2 NPs induced the down-regulation of super oxide dismutase gene while the up-regulation of heme oxygenase-1 gene in MCF-7 cells. Cytotoxicity induced by Zn-doped TiO2 NPs was efficiently prevented by N-acetyl-cysteine suggesting that oxidative stress might be the primarily cause of toxicity. In conclusion, our data indicated that Zn-doping decreases the particle size and increases the band gap energy as well the oxidative stress-mediated toxicity of TiO2 NPs in MCF-7 cells. PMID:27444578

  1. Role of Zn doping in oxidative stress mediated cytotoxicity of TiO2 nanoparticles in human breast cancer MCF-7 cells

    NASA Astrophysics Data System (ADS)

    Ahamed, Maqusood; Khan, M. A. Majeed; Akhtar, Mohd Javed; Alhadlaq, Hisham A.; Alshamsan, Aws

    2016-07-01

    We investigated the effect of Zn-doping on structural and optical properties as well as cellular response of TiO2 nanoparticles (NPs) in human breast cancer MCF-7 cells. A library of Zn-doped (1–10 at wt%) TiO2 NPs was prepared. Characterization data indicated that dopant Zn was incorporated into the lattice of host TiO2. The average particle size of TiO2 NPs was decreases (38 to 28 nm) while the band gap energy was increases (3.35 eV–3.85 eV) with increasing the amount of Zn-doping. Cellular data demonstrated that Zn-doped TiO2 NPs induced cytotoxicity (cell viability reduction, membrane damage and cell cycle arrest) and oxidative stress (reactive oxygen species generation & glutathione depletion) in MCF-7 cells and toxic intensity was increases with increasing the concentration of Zn-doping. Molecular data revealed that Zn-doped TiO2 NPs induced the down-regulation of super oxide dismutase gene while the up-regulation of heme oxygenase-1 gene in MCF-7 cells. Cytotoxicity induced by Zn-doped TiO2 NPs was efficiently prevented by N-acetyl-cysteine suggesting that oxidative stress might be the primarily cause of toxicity. In conclusion, our data indicated that Zn-doping decreases the particle size and increases the band gap energy as well the oxidative stress-mediated toxicity of TiO2 NPs in MCF-7 cells.

  2. A novel nanocomposite based on TiO2/Cu2O/reduced graphene oxide with enhanced solar-light-driven photocatalytic activity

    NASA Astrophysics Data System (ADS)

    Almeida, Bruna M.; Melo, Maurício A., Jr.; Bettini, Jefferson; Benedetti, João E.; Nogueira, Ana F.

    2015-01-01

    A novel nanocomposite composed of TiO2 and Cu2O nanoparticles combined with reduced graphene oxide (RGO) was synthesized and characterized. X-ray diffraction (XRD), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), UV-vis diffuse reflectance spectroscopy (UV-vis DRS), X-ray photoelectron spectroscopy (XPS), thermogravimetry (TG) and elemental analysis were employed to investigate the structure, morphology, optical properties and composition of the nanocomposite and the intermediate materials. The photocatalytic activity of TiO2/Cu2O/RGO and the individual materials were studied through the photodegradation of methylene blue under solar radiation. A considerable increase in the photodegradation activity using the nanocomposite was obtained after 5 h (∼95% of MB degradation). Photoelectrochemical studies were carried out and confirmed the superiority of the novel nanocomposite in the photocurrent generation. The highest activity resulted from the synergy of this carbonaceous structure with TiO2 and Cu2O, which could absorb a wider portion of the solar spectrum, adsorb higher quantities of methylene blue on the surface and improve the effective separation of the generated electron-hole pairs.

  3. The design, fabrication, and photocatalytic utility of nanostructured semiconductors: focus on TiO2-based nanostructures

    PubMed Central

    Banerjee, Arghya Narayan

    2011-01-01

    Recent advances in basic fabrication techniques of TiO2-based nanomaterials such as nanoparticles, nanowires, nanoplatelets, and both physical- and solution-based techniques have been adopted by various research groups around the world. Our research focus has been mainly on various deposition parameters used for fabricating nanostructured materials, including TiO2-organic/inorganic nanocomposite materials. Technically, TiO2 shows relatively high reactivity under ultraviolet light, the energy of which exceeds the band gap of TiO2. The development of photocatalysts exhibiting high reactivity under visible light allows the main part of the solar spectrum to be used. Visible light-activated TiO2 could be prepared by doping or sensitizing. As far as doping of TiO2 is concerned, in obtaining tailored material with improved properties, metal and nonmetal doping has been performed in the context of improved photoactivity. Nonmetal doping seems to be more promising than metal doping. TiO2 represents an effective photocatalyst for water and air purification and for self-cleaning surfaces. Additionally, it can be used as an antibacterial agent because of its strong oxidation activity and superhydrophilicity. Therefore, applications of TiO2 in terms of photocatalytic activities are discussed here. The basic mechanisms of the photoactivities of TiO2 and nanostructures are considered alongside band structure engineering and surface modification in nanostructured TiO2 in the context of doping. The article reviews the basic structural, optical, and electrical properties of TiO2, followed by detailed fabrication techniques of 0-, 1-, and quasi-2-dimensional TiO2 nanomaterials. Applications and future directions of nanostructured TiO2 are considered in the context of various photoinduced phenomena such as hydrogen production, electricity generation via dye-sensitized solar cells, photokilling and self-cleaning effect, photo-oxidation of organic pollutant, wastewater management, and

  4. Highly flexible coaxial nanohybrids made from porous TiO2 nanotubes.

    PubMed

    Wang, Daoai; Liu, Ying; Wang, Chengwei; Zhou, Feng; Liu, Weimin

    2009-05-26

    Anatase TiO(2), an n-type semiconductor, has gained considerable research interest over several decades due to its photocatalytic activity. Most recently, its properties for photoelectrical conversion in solar cells has been explored. Anodized TiO(2) nanotube (NT) arrays have been developed and possess improved photocatalytic, sensing, photoelectrolystic, and photovoltaic properties. The present work describes using TiO(2) as the building block to form ordered heterojunctions via simple electrodeposition with materials of potential interest, including conducting polymers (polypyrrole, poly(3-hexylthiophene)), inorganic semiconducting materials (CdS), and metals (Ni and Au, etc.). A key finding is that the synthesized TiO(2) NT-nanowires(nanotubes) nanohybrids are highly flexible after being peeled off from mother substrates, which is in contrast to more fragile pure TiO(2) NTs. These highly flexible coaxial nanohybrids are expected to have potent applications.

  5. Proliferation and stemness preservation of human adipose-derived stem cells by surface-modified in situ TiO2 nanofibrous surfaces

    PubMed Central

    Tan, Ai Wen; Tay, Lelia; Chua, Kien Hui; Ahmad, Roslina; Ali Akbar, Sheikh; Pingguan-Murphy, Belinda

    2014-01-01

    Two important criteria of an ideal biomaterial in the field of stem cells research are to regulate the cell proliferation without the loss of its pluripotency and to direct the differentiation into a specific cell lineage when desired. The present study describes the influence of TiO2 nanofibrous surface structures on the regulation of proliferation and stemness preservation of adipose-derived stem cells (ADSCs). TiO2 nanofiber arrays were produced in situ onto Ti-6Al-4V substrate via a thermal oxidation process and the successful fabrication of these nanostructures was confirmed by field emission scanning electron microscopy (FESEM), energy dispersive spectrometer (EDS), X-ray diffractometer (XRD), and contact angle measurement. ADSCs were seeded on two types of Ti-6Al-4V surfaces (TiO2 nanofibers and flat control), and their morphology, proliferation, and stemness expression were analyzed using FESEM, AlamarBlue assay, flow cytometry, and quantitative real-time polymerase chain reaction (qRT-PCR) after 2 weeks of incubation, respectively. The results show that ADSCs exhibit better adhesion and significantly enhanced proliferation on the TiO2 nanofibrous surfaces compared to the flat control surfaces. The greater proliferation ability of TiO2 nanofibrous surfaces was further confirmed by the results of cell cycle assay. More importantly, TiO2 nanofibrous surfaces significantly upregulate the expressions of stemness markers Sox-2, Nanog3, Rex-1, and Nestin. These results demonstrate that TiO2 nanofibrous surfaces can be used to enhance cell adhesion and proliferation while simultaneously maintaining the stemness of ADSCs, thereby representing a promising approach for their potential application in the field of bone tissue engineering as well as regenerative therapies. PMID:25473278

  6. Controlling mesenchymal stem cells differentiate into contractile smooth muscle cells on a TiO2 micro/nano interface: Towards benign pericytes environment for endothelialization.

    PubMed

    Li, Jingan; Qin, Wei; Zhang, Kun; Wu, Feng; Yang, Ping; He, Zikun; Zhao, Ansha; Huang, Nan

    2016-09-01

    Building healthy and oriented smooth muscle cells (SMCs) environment is an effective method for improving the surface endothelialization of the cardiovascular implants. However, a long-term and stable source of SMCs for implantation without immune rejection and inflammation has not been solved, and mesenchymal stem cells (MSCs) differentiation may be a good choice. In this work, two types of TiO2 micro/nano interfaces were fabricated on titanium surface by photolithography and anodic oxidation. These TiO2 micro/nano interfaces were used to regulate the differentiation of the MSCs. The X-ray diffraction (XRD) detection showed that the TiO2 micro/nano interfaces possessed the anatase crystal structure, suggesting good cytocompatibility. The CCK-8 results indicated the TiO2 micro/nano interfaces improved MSC proliferation, further immunofluorescence staining and calculation of the cell morphology index proved the micro/nano surfaces also elongated MSCs and regulated MSCs oriented growth. The specific staining of α-SMA, CNN-1, vWF, CD44 and CD133 markers revealed that the micro/nano surfaces induced MSCs differentiation to contractile SMCs, and the endothelial cells (ECs) culture experiment indicated that the MSCs induced by micro/nano interfaces contributed to the ECs attachment and proliferation. This method will be further studied and applied for the surface modification of the cardiovascular implants.

  7. Controlling mesenchymal stem cells differentiate into contractile smooth muscle cells on a TiO2 micro/nano interface: Towards benign pericytes environment for endothelialization.

    PubMed

    Li, Jingan; Qin, Wei; Zhang, Kun; Wu, Feng; Yang, Ping; He, Zikun; Zhao, Ansha; Huang, Nan

    2016-09-01

    Building healthy and oriented smooth muscle cells (SMCs) environment is an effective method for improving the surface endothelialization of the cardiovascular implants. However, a long-term and stable source of SMCs for implantation without immune rejection and inflammation has not been solved, and mesenchymal stem cells (MSCs) differentiation may be a good choice. In this work, two types of TiO2 micro/nano interfaces were fabricated on titanium surface by photolithography and anodic oxidation. These TiO2 micro/nano interfaces were used to regulate the differentiation of the MSCs. The X-ray diffraction (XRD) detection showed that the TiO2 micro/nano interfaces possessed the anatase crystal structure, suggesting good cytocompatibility. The CCK-8 results indicated the TiO2 micro/nano interfaces improved MSC proliferation, further immunofluorescence staining and calculation of the cell morphology index proved the micro/nano surfaces also elongated MSCs and regulated MSCs oriented growth. The specific staining of α-SMA, CNN-1, vWF, CD44 and CD133 markers revealed that the micro/nano surfaces induced MSCs differentiation to contractile SMCs, and the endothelial cells (ECs) culture experiment indicated that the MSCs induced by micro/nano interfaces contributed to the ECs attachment and proliferation. This method will be further studied and applied for the surface modification of the cardiovascular implants. PMID:27232304

  8. Nb doped TiO2 as a Cathode Catalyst Support Material for Polymer Electrolyte Membrane Fuel Cells

    NASA Astrophysics Data System (ADS)

    O'Toole, Alexander W.

    In order to reduce the emissions of greenhouse gases and reduce dependence on the use of fossil fuels, it is necessary to pursue alternative sources of energy. Transportation is a major contributor to the emission of greenhouse gases due to the use of fossil fuels in the internal combustion engine. To reduce emission of these pollutants into the atmosphere, research is needed to produce alternative solutions for vehicle transportation. Low temperature polymer electrolyte membrane fuel cells are energy conversion devices that provide an alternative to the internal combustion engine, however, they still have obstacles to overcome to achieve large scale implementation. T he following work presents original research with regards to the development of Nb doped TiO2 as a cathode catalyst support material for low temperature polymer electrolyte membrane fuel cells. The development of a new process to synthesize nanoparticles of Nb doped TiO2 with controlled compositions is presented as well as methods to scale up the process and optimize the synthesis for the aforementioned application. In addition to this, comparison of both electrochemical activity and durability with current state of the art Pt on high surface area carbon black (Vulcan XC-72) is investigated. Effects of the strong metal-support interaction on the electrochemical behavior of these materials is also observed and discussed.

  9. High-performance method for specific effect on nucleic acids in cells using TiO2~DNA nanocomposites

    NASA Astrophysics Data System (ADS)

    Levina, Asya S.; Repkova, Marina N.; Ismagilov, Zinfer R.; Shikina, Nadezhda V.; Malygin, Ernst G.; Mazurkova, Natalia A.; Zinov'ev, Victor V.; Evdokimov, Alexei A.; Baiborodin, Sergei I.; Zarytova, Valentina F.

    2012-10-01

    Nanoparticles are used to solve the current drug delivery problem. We present a high-performance method for efficient and selective action on nucleic acid target in cells using unique TiO2.PL-DNA nanocomposites (polylysine-containing DNA fragments noncovalently immobilized onto TiO2 nanoparticles capable of transferring DNA). These nanocomposites were used for inhibition of human influenza A (H3N2) virus replication in infected MDCK cells. They showed a low toxicity (TC50 ~ 1800 μg/ml) and a high antiviral activity (>99.9% inhibition of the virus replication). The specificity factor (antisense effect) appeared to depend on the delivery system of DNA fragments. This factor for nanocomposites is ten-times higher than for DNA in the presence of lipofectamine. IC50 for nanocomposites was estimated to be 1.5 μg/ml (30 nM for DNA), so its selectivity index was calculated as ~1200. Thus, the proposed nanocomposites are prospective for therapeutic application.

  10. Design of hybrid nanoheterostructure systems for enhanced quantum and solar conversion efficiencies in dye-sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Kılıç, Bayram; Telli, Hakan; Tüzemen, Sebahattin; Başaran, Ali; Pirge, Gursev

    2015-04-01

    Dye sensitized solar cells (DSSCs) with an innovative design involving controlled-morphology vertically aligned (VA) ZnO nanowires within mesoporous TiO2 structures with ultrahigh surface area for implementation as photoanodes are herein reported. Although TiO2 nanostructures exhibit excellent power conversion efficiency, the electron transport rate is low owing to low electron mobility. To overcome this, ZnO nanowires with high electron mobility have been investigated as potential candidates for photoanodes. However, the power conversion efficiency of ZnO nanowires is still lower than that of TiO2 owing to their low internal surface area. Consequently, in this work, vertical growth of ZnO nanowires within mesoporous TiO2 structures is carried out to increase their solar power conversion efficiency. The photovoltaic performance of solar cells using ZnO nanowires, mesoporous TiO2, and TiO2/ZnO hybrid structures are compared. The VA TiO2/ZnO hybrid structures are found to provide direct electron transfer compared with the tortuous pathway of zero-dimensional nanostructures, resulting in an increased conversion efficiency. It is demonstrated that the light scattering of the photoanode film is increased and electron recombination is decreased when an appropriate amount of mesoporous TiO2 is used as a substrate for ZnO nanowires. The DSSC fabricated with the TiO2/ZnO hybrid photoanode prepared with 15.8 wt. % TiO2 showed the highest conversion efficiency of 7.30%, approximately 5%, 18%, and 40% higher than that of DSSCs fabricated with 3.99 wt. % TiO2, pure TiO2, and pure ZnO photoanodes, respectively.

  11. Phototoxicity of TiO2 Nanoparticles under Solar Radiation to Two Aquatic Species: Daphnia magna and Japanese Medaka

    EPA Science Inventory

    One target of development and application of TiO2 nanoparticles (nano-TiO2) is photochemical degredation of contaminants and photo-killing of microbes and fouling organisms. However, few ecotoxicological studies have focused on this aspect of nano-TiO2, specifically whether this ...

  12. Strategies to prepare TiO2 thin films, doped with transition metal ions, that exhibit specific physicochemical properties to support osteoblast cell adhesion and proliferation.

    PubMed

    Dhayal, Marshal; Kapoor, Renu; Sistla, Pavana Goury; Pandey, Ravi Ranjan; Kar, Satabisha; Saini, Krishan Kumar; Pande, Gopal

    2014-04-01

    Metal ion doped titanium oxide (TiO2) thin films, as bioactive coatings on metal or other implantable materials, can be used as surfaces for studying the cell biological properties of osteogenic and other cell types. Bulk crystallite phase distribution and surface carbon-oxygen constitution of thin films, play an important role in determining the biological responses of cells that come in their contact. Here we present a strategy to control the polarity of atomic interactions between the dopant metal and TiO2 molecules and obtain surfaces with smaller crystallite phases and optimal surface carbon-oxygen composition to support the maximum proliferation and adhesion of osteoblast cells. Our results suggest that surfaces, in which atomic interactions between the dopant metals and TiO2 were less polar, could support better adhesion, spreading and proliferation of cells.

  13. Self-assembly graphitic carbon nitride quantum dots anchored on TiO2 nanotube arrays: An efficient heterojunction for pollutants degradation under solar light.

    PubMed

    Su, Jingyang; Zhu, Lin; Geng, Ping; Chen, Guohua

    2016-10-01

    In this study, an efficient heterojunction was constructed by anchoring graphitic carbon nitride quantum dots onto TiO2 nanotube arrays through hydrothermal reaction strategy. The prepared graphitic carbon nitride quantum dots, which were prepared by solid-thermal reaction and sequential dialysis process, act as a sensitizer to enhance light absorption. Furthermore, it was demonstrated that the charge transfer and separation in the formed heterojunction were significantly improved compared with pristine TiO2. The prepared heterojunction was used as a photoanode, exhibiting much improved photoelectrochemical capability and excellent photo-stability under solar light illumination. The photoelectrocatalytic activities of prepared heterojunction were demonstrated by degradation of RhB and phenol in aqueous solution. The kinetic constants of RhB and phenol degradation using prepared photoelectrode are 2.4 times and 4.9 times higher than those of pristine TiO2, respectively. Moreover, hydroxyl radicals are demonstrated to be dominant active radicals during the pollutants degradation.

  14. Synthesis, features and solar-light-driven photocatalytic activity of TiO2 nanotube arrays loaded with SnO2.

    PubMed

    Sim, Lan Ching; Ng, Kai Wern; Ibrahim, Shaliza; Saravanan, Pichiah

    2014-09-01

    In the present study TiO2 nanotube arrays (TNTs) were loaded with a post-transition metal oxide particles namely SnO2 via incipient wet impregnation method by varying its concentration (1.59 wt%, 2.25 wt% and 2.84 wt%). The photocatalytic activity of the prepared photocatalyst was evaluated for the degradation of methylene blue (MB) in presence of natural solar light irradiation. The morphological analyses revealed that the prepared TNTs had average inner diameter of 109 nm, wall thickness of 15 nm and tube length of 7-10 μm, respectively, while the crystalline phase and Raman spectra confirmed the 100% anatase mineral form of TiO2. Further, the presence of SnO2 in TNTs was confirmed by high resolution transmission electron microscopy (HRTEM) and X-ray photoelectron spectroscopy (XPS). The visible light absorption properties of TNTs improved drastically with increasing SnO2 loadings. The coupling effect of SnO2 and TiO2 significantly enhanced degradation efficiency of MB. An 84% degradation of MB was achieved in 6 h of irradiation under clear sky condition. PMID:25924362

  15. SaOS-2 cell response to macro-porous boron-incorporated TiO2 coating prepared by micro-arc oxidation on titanium.

    PubMed

    Huang, Qianli; Elkhooly, Tarek A; Liu, Xujie; Zhang, Ranran; Yang, Xing; Shen, Zhijian; Feng, Qingling

    2016-10-01

    The aims of the present study were to develop boron-incorporated TiO2 coating (B-TiO2 coating) through micro-arc oxidation (MAO) and subsequently evaluate the effect of boron incorporation on the in vitro biological performance of the coatings. The physicochemical properties of B-TiO2 coating and its response to osteoblast like cells (SaOS-2) were investigated compared to the control group without boron (TiO2 coating). The morphological and X-ray diffraction results showed that both coatings exhibited similar surface topography and phase composition, respectively. However, the incorporation of B led to an enhancement in the surface hydrophilicity of B-TiO2 coating. The spreading of SaOS-2 cells on B-TiO2 coating was faster than that on TiO2 coating. The proliferation rate of SaOS-2 cells cultured on B-TiO2 decreased after 5days of culture compared to that on TiO2 coating. SaOS-2 cells cultured on B-TiO2 coating exhibited an enhanced alkaline phosphatase (ALP) activity, Collagen I synthesis and in vitro mineralization compared to those on TiO2 coating. The present findings suggest that B-TiO2 coating is a promising candidate surface for orthopedic implants.

  16. Nanostructured TiO2 Films Attached CdSe QDs Toward Enhanced Photoelectrochemical Performance.

    PubMed

    Du, Yingying; Yang, Ping; Liu, Yunshi; Zhao, Jie; He, Haiyan; Miao, Yanping

    2016-06-01

    TiO2 films consisted of small nanoparticles were fabricated via a spinning coating method on fluorine doped in tin oxide (FTO) slide glass. After calcination, the films were subsequently sensitized by CdSe quantum dots (QDs) using mercaptopropionic acid (MPA) as a bifunctional surface modifier. Upon UV light irradiation, CdSe QDs inject electrons into TiO2 nanoparticles, thus resulting in the generation of photocurrent in QD-sensitized solar cell. The results indicate that TiO2 films sensitized by CdSe QDs have achieved 1.5-fold enhancement in photocurrent compared with pure TiO2 films, indicating that CdSe QDs can improve the photocurrent by promoting the separation of photoinduced charge carriers. In addition, the photocurrent enhances as the thickness of TiO2 films increased. Such improved photoelectrochemical performance is ascribed to the basis of improved interfacial charge transport of the TiO2-CdSe composite films. Combining QDs on TiO2 thin films is a promising and effective way to enhance the photoelectrochemical performance, which is important in QD-sensitized solar cell application. PMID:27427714

  17. Oxidative Stress and Nano-Toxicity Induced by TiO2 and ZnO on WAG Cell Line

    PubMed Central

    Dubey, Akhilesh; Goswami, Mukunda; Yadav, Kamalendra; Chaudhary, Dharmendra

    2015-01-01

    Metallic nanoparticles are widely used in cosmetics, food products and textile industry. These particles are known to cause respiratory toxicity and epithelial inflammation. They are eventually released to aquatic environment necessitating toxicity studies in cells from respiratory organs of aquatic organisms. Hence, we have developed and characterized a new cell line, WAG, from gill tissue of Wallago attu for toxicity assessment of TiO2 and ZnO nanoparticles. The efficacy of the cell line as an in vitro system for nanoparticles toxicity studies was established using electron microscopy, cytotoxicity assays, genotoxicity assays and oxidative stress biomarkers. Results obtained with MTT assay, neutral red uptake assay and lactate dehydrogenase assay showed acute toxicity to WAG cells with IC50 values of 25.29±0.12, 34.99±0.09 and 35.06±0.09 mg/l for TiO2 and 5.716±0.1, 3.160±0.1 and 5.57±0.12 mg/l for ZnO treatment respectively. The physicochemical properties and size distribution of nanoparticles were characterized using electron microscopy with integrated energy dispersive X-ray spectroscopy and Zetasizer. Dose dependent increase in DNA damage, lipid peroxidation and protein carbonylation along with a significant decrease in activity of Superoxide Dismutase, Catalase, total Glutathione levels and total antioxidant capacity with increasing concentration of exposed nanoparticles indicated that the cells were under oxidative stress. The study established WAG cell line as an in vitro system to study toxicity mechanisms of nanoparticles on aquatic organisms. PMID:26011447

  18. Enhancement of solar light photocatalytic activity of TiO2-CeO2 composite by Er3+:Y3Al5O12 in organic dye degradation

    NASA Astrophysics Data System (ADS)

    Li, Y.; Li, S. G.; Zhang, L.; Wang, J.; Li, Y.; Ma, C. H.

    2014-12-01

    The Er3+:Y3Al5O12, as an upconversion luminescence agent which is able to transform the visible part of the solar light to ultraviolet light, was prepared by nitrate-citrate sol-gel method. A novel solar light photocatalyst, Er3+:Y3Al5O12/TiO2-CeO2 composite was synthesized using ultrasonic treatment. The X-ray diffraction (XRD) and scanning election microscopy (SEM) were used to characterize the structural morphology of the Er3+:Y3Al5O12/TiO2-CeO2 composite. In order to evaluate the solar light photocatalytic activity of Er3+:Y3Al5O12/TiO2-CeO2 composite, the Azo Fuchsine dye was used as a model organic pollutant. The progress of the degradation reaction was monitored by UV-Vis spectroscopy and ion chromatography. The key influences on the solar light photocatalytic activity of Er3+:Y3Al5O12/TiO2-CeO2 were studied, such as Ti/Ce molar ratio, heat-treatment temperature and heat-treatment time. Otherwise, the effects of initial dye concentration, Er3+:Y3Al5O12/TiO2-CeO2 amount, solar light irradiation time and the nature of the dye on the solar light photocatalytic degradation process were investigated. It was found that the solar light photocatalytic activity of Er3+:Y3Al5O12/TiO2-CeO2 composite was superior to Er3+:Y3Al5O12/TiO2 and Er3+:Y3Al5O12/CeO2 powder in the similar conditions.

  19. Strong electronic coupling and ultrafast electron transfer between PbS quantum dots and TiO2 nanocrystalline films.

    PubMed

    Yang, Ye; Rodríguez-Córdoba, William; Xiang, Xu; Lian, Tianquan

    2012-01-11

    Hot carrier and multiple exciton extractions from lead salt quantum dots (QDs) to TiO(2) single crystals have been reported. Implementing these ideas on practical solar cells likely requires the use of nanocrystalline TiO(2) thin films to enhance the light harvesting efficiency. Here, we report 6.4 ± 0.4 fs electron transfer time from PbS QDs to TiO(2) nanocrystalline thin films, suggesting the possibility of extracting hot carriers and multiple excitons in solar cells based on these materials.

  20. TiO2-doped phosphate glass microcarriers: A stable bioactive substrate for expansion of adherent mammalian cells

    PubMed Central

    Guedes, Joana C; Park, Jeong-Hui; Lakhkar, Nilay J; Kim, Hae-Won; Knowles, Jonathan C

    2013-01-01

    Scalable expansion of cells for regenerative cell therapy or to produce large quantities for high-throughput screening remains a challenge for bioprocess engineers. Laboratory scale cell expansion using t-flasks requires frequent passaging that exposes cells to many poorly defined bioprocess forces that can cause damage or alter their phenotype. Microcarriers offer a potential solution to scalable production, lending themselves to cell culture processes more akin to fermentation, removing the need for frequent passaging throughout the expansion period. One main problem with microcarrier expansion, however, is the difficulty in harvesting cells at the end of the process. Therefore, therapies that rely on cell delivery using biomaterial scaffolds could benefit from a microcarrier expansion system whereby the cells and microcarriers are transplanted together. In the current study, we used bioactive glass microcarriers doped with 5% TiO2 that display a controlled rate of degradation and conducted experiments to assess biocompatibility and growth of primary fibroblast cells as a model for cell therapy products. We found that the microcarriers are highly biocompatible and facilitate cell growth in a gradual controlled manner. Therefore, even without additional biofunctionalization methods, Ti-doped bioactive glass microcarriers offer potential as a cell expansion platform. PMID:22935537

  1. Intestinal toxicity evaluation of TiO2 degraded surface-treated nanoparticles: a combined physico-chemical and toxicogenomics approach in caco-2 cells

    PubMed Central

    2012-01-01

    Background Titanium dioxide (TiO2) nanoparticles (NPs) are widely used due to their specific properties, like UV filters in sunscreen. In that particular case TiO2 NPs are surface modified to avoid photocatalytic effects. These surface-treated nanoparticles (STNPs) spread in the environment and might release NPs as degradation residues. Indeed, degradation by the environment (exposure to UV, water and air contact …) will occur and could profoundly alter the physicochemical properties of STNPs such as chemistry, size, shape, surface structure and dispersion that are important parameters for toxicity. Although the toxicity of surface unmodified TiO2 NPs has been documented, nothing was done about degraded TiO2 STNPs which are the most likely to be encountered in environment. The superoxide production by aged STNPs suspensions was tested and compared to surface unmodified TiO2 NPs. We investigated the possible toxicity of commercialized STNPs, degraded by environmental conditions, on human intestinal epithelial cells. STNPs sizes and shape were characterized and viability tests were performed on Caco-2 cells exposed to STNPs. The exposed cells were imaged with SEM and STNPs internalization was researched by TEM. Gene expression microarray analyses were performed to look for potential changes in cellular functions. Results The production of reactive oxygen species was detected with surface unmodified TiO2 NPs but not with STNPs or their residues. Through three different toxicity assays, the STNPs tested, which have a strong tendency to aggregate in complex media, showed no toxic effect in Caco-2 cells after exposures to STNPs up to 100 μg/mL over 4 h, 24 h and 72 h. The cell morphology remained intact, attested by SEM, and internalization of STNPs was not seen by TEM. Moreover gene expression analysis using pangenomic oligomicroarrays (4x 44000 genes) did not show any change versus unexposed cells after exposure to 10 μg/ mL, which is much higher than

  2. Integration of CdSe/CdSexTe1−x Type-II Heterojunction Nanorods into Hierarchically Porous TiO2 Electrode for Efficient Solar Energy Conversion

    PubMed Central

    Lee, Sangheon; Flanagan, Joseph C.; Kang, Joonhyeon; Kim, Jinhyun; Shim, Moonsub; Park, Byungwoo

    2015-01-01

    Semiconductor sensitized solar cells, a promising candidate for next-generation photovoltaics, have seen notable progress using 0-D quantum dots as light harvesting materials. Integration of higher-dimensional nanostructures and their multi-composition variants into sensitized solar cells is, however, still not fully investigated despite their unique features potentially beneficial for improving performance. Herein, CdSe/CdSexTe1−x type-II heterojunction nanorods are utilized as novel light harvesters for sensitized solar cells for the first time. The CdSe/CdSexTe1−x heterojunction-nanorod sensitized solar cell exhibits ~33% improvement in the power conversion efficiency compared to its single-component counterpart, resulting from superior optoelectronic properties of the type-II heterostructure and 1-octanethiol ligands aiding facile electron extraction at the heterojunction nanorod-TiO2 interface. Additional ~32% enhancement in power conversion efficiency is achieved by introducing percolation channels of large pores in the mesoporous TiO2 electrode, which allow 1-D sensitizers to infiltrate the entire depth of electrode. These strategies combined together lead to 3.02% power conversion efficiency, which is one of the highest values among sensitized solar cells utilizing 1-D nanostructures as sensitizer materials. PMID:26638994

  3. Dual effects and mechanism of TiO2 nanotube arrays in reducing bacterial colonization and enhancing C3H10T1/2 cell adhesion.

    PubMed

    Peng, Zhaoxiang; Ni, Jiahua; Zheng, Kang; Shen, Yandong; Wang, Xiaoqing; He, Guo; Jin, Sungho; Tang, Tingting

    2013-01-01

    Competition occurs between the osteoblasts in regional microenvironments and pathogens introduced during surgery, on the surface of bone implants, such as joint prostheses. The aim of this study was to modulate bacterial and osteoblast adhesion on implant surfaces by using a nanotube array. Titanium oxide (TiO2) nanotube arrays, 30 nm or 80 nm in diameter, were prepared by a two-step anodization on titanium substrates. Mechanically polished and acid-etched titanium samples were also prepared to serve as control groups. The standard strains of Staphylococcus epidermidis (S. epidermidis, American Type Culture Collection [ATCC]35984) and mouse C3H10T1/2 cell lines with osteogenic potential were used to evaluate the different responses to the nanotube arrays, in bacteria and eukaryotic cells. We found that the initial adhesion and colonization of S. epidermidis on the surface of the TiO2 nanotube arrays were significantly reduced and that the adhesion of C3H10T1/2 cells on the surface of the TiO2 nanotube arrays was significantly enhanced when compared with the control samples. Based on a surface analysis of all four groups, we observed increased surface roughness, decreased water contact angles, and an enhanced concentration of oxygen and fluorine atoms on the TiO2 nanotube surface. We conclude that the TiO2 nanotube surface can reduce bacterial colonization and enhance C3H10T1/2 cell adhesion; multiple physical and chemical properties of the TiO2 nanotube surface may contribute to these dual effects. PMID:23983463

  4. Dual effects and mechanism of TiO2 nanotube arrays in reducing bacterial colonization and enhancing C3H10T1/2 cell adhesion

    PubMed Central

    Peng, Zhaoxiang; Ni, Jiahua; Zheng, Kang; Shen, Yandong; Wang, Xiaoqing; He, Guo; Jin, Sungho; Tang, Tingting

    2013-01-01

    Competition occurs between the osteoblasts in regional microenvironments and pathogens introduced during surgery, on the surface of bone implants, such as joint prostheses. The aim of this study was to modulate bacterial and osteoblast adhesion on implant surfaces by using a nanotube array. Titanium oxide (TiO2) nanotube arrays, 30 nm or 80 nm in diameter, were prepared by a two-step anodization on titanium substrates. Mechanically polished and acid-etched titanium samples were also prepared to serve as control groups. The standard strains of Staphylococcus epidermidis (S. epidermidis, American Type Culture Collection [ATCC]35984) and mouse C3H10T1/2 cell lines with osteogenic potential were used to evaluate the different responses to the nanotube arrays, in bacteria and eukaryotic cells. We found that the initial adhesion and colonization of S. epidermidis on the surface of the TiO2 nanotube arrays were significantly reduced and that the adhesion of C3H10T1/2 cells on the surface of the TiO2 nanotube arrays was significantly enhanced when compared with the control samples. Based on a surface analysis of all four groups, we observed increased surface roughness, decreased water contact angles, and an enhanced concentration of oxygen and fluorine atoms on the TiO2 nanotube surface. We conclude that the TiO2 nanotube surface can reduce bacterial colonization and enhance C3H10T1/2 cell adhesion; multiple physical and chemical properties of the TiO2 nanotube surface may contribute to these dual effects. PMID:23983463

  5. Dynamics of Electron Injection in SnO2/TiO2 Core/Shell Electrodes for Water-Splitting Dye-Sensitized Photoelectrochemical Cells.

    PubMed

    McCool, Nicholas S; Swierk, John R; Nemes, Coleen T; Schmuttenmaer, Charles A; Mallouk, Thomas E

    2016-08-01

    Water-splitting dye-sensitized photoelectrochemical cells (WS-DSPECs) rely on photoinduced charge separation at a dye/semiconductor interface to supply electrons and holes for water splitting. To improve the efficiency of charge separation and reduce charge recombination in these devices, it is possible to use core/shell structures in which photoinduced electron transfer occurs stepwise through a series of progressively more positive acceptor states. Here, we use steady-state emission studies and time-resolved terahertz spectroscopy to follow the dynamics of electron injection from a photoexcited ruthenium polypyridyl dye as a function of the TiO2 shell thickness on SnO2 nanoparticles. Electron injection proceeds directly into the SnO2 core when the thickness of the TiO2 shell is less than 5 Å. For thicker shells, electrons are injected into the TiO2 shell and trapped, and are then released into the SnO2 core on a time scale of hundreds of picoseconds. As the TiO2 shell increases in thickness, the probability of electron trapping in nonmobile states within the shell increases. Conduction band electrons in the TiO2 shell and the SnO2 core can be differentiated on the basis of their mobility. These observations help explain the observation of an optimum shell thickness for core/shell water-splitting electrodes.

  6. Cubic titanium dioxide photoanode for dye-sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Chae, Jinho; Kang, Misook

    Following from the recently evolved concept of significantly improving the photovoltaic efficiency in dye-sensitized solar cells (DSSCs) by reducing the loss of electrons on the spherical surface of titanium dioxide, this study examines the synthesis of cubic TiO 2 with a special morphology to overcome this electron loss and investigates its application to DSSCs. Cubic TiO 2 is synthesized by an advanced rapid hydrothermal method, with the addition of an amine species additive. Transmission electron microscopy (TEM) images confirm the cubic shape of the TiO 2 particles with a diameter less than 5-10 nm. Using N719 dye under illumination with 100 mW cm -2 simulated sunlight, the application of cubic TiO 2 to DSSCs affords an energy conversion efficiency of approximately 9.77% (4.0-μm thick TiO 2 film), which is considerably enhanced compared with that achieved using a commercial, spherical TiO 2. Electrostatic force microscopy (EFM) and impedance analyses reveal that the electrons are transferred more rapidly to the surface of a cubic TiO 2 film than on a spherical TiO 2 film.

  7. Dual-Wavelength Irradiation and Dox Delivery for -Cancer Cell Ablation with Photocatalytic Pr Doped TiO2 /NGO -Hybrid Nanocomposite.

    PubMed

    Jang, Hongje; Choi, Myung-Ho; Yim, Yeajee; Kim, Young-Kwan; Min, Dal-Hee

    2015-08-26

    Herein, hybrid nanocomposite of praseodymium doped TiO2 nanocrystals and graphene oxide nanosheets are prepared by facile hydrothermal treatment. As-synthesized Pr-TiO2 /NGO hybrid nanocomposite exhibits enhanced photocatalytic activity under visible light irradiation by the intact graphene oxide and doped lanthanide mediated band gap narrowing compared to TiO2 . Moreover, high payload and controlled release of doxorubicin by charge reversal of hybrid nanocomposite at endosomal pH and near-infrared irradiation mediated efficient photothermal conversion provide highly favorable features in therapeutic applications. Through the combination of these three distinctive therapeutic modalities, highly efficient trimodal cancer cell ablation is demonstrated. PMID:26085286

  8. Combined cytotoxic effect of UV-irradiation and TiO2 microbeads in normal urothelial cells, low-grade and high-grade urothelial cancer cells.

    PubMed

    Imani, Roghayeh; Veranič, Peter; Iglič, Aleš; Kreft, Mateja Erdani; Pazoki, Meysam; Hudoklin, Samo

    2015-03-01

    The differentiation of urothelial cells results in normal terminally differentiated cells or by alternative pathways in low-grade or high-grade urothelial carcinomas. Treatments with traditional surgical and chemotherapeutical approaches are still inadequate and expensive, as bladder tumours are generally highly recurrent. In such situations, alternative approaches, using irradiation of the cells and nanoparticles, are promising. The ways in which urothelial cells, at different differentiation levels, respond to UV-irradiation (photolytic treatment) or to the combination of UV-irradiation and nanoparticles (photocatalytic treatment), are unknown. Here we tested cytotoxicity of UV-irradiation on (i) normal porcine urothelial cells (NPU), (ii) human low-grade urothelial cancer cells (RT4), and (iii) human high-grade urothelial cancer cells (T24). The results have shown that 1 minute of UV-irradiation is enough to kill 90% of the cells in NPU and RT4 cultures, as determined by the live/dead viability assay. On the other hand, the majority of T24 cells survived 1 minute of UV-irradiation. Moreover, even a prolonged UV-irradiation for 30 minutes killed <50% of T24 cells. When T24 cells were pre-supplemented with mesoporous TiO2 microbeads and then UV-irradiated, the viability of these high-grade urothelial cancer cells was reduced to <10%, which points to the highly efficient cytotoxic effects of TiO2 photocatalysis. Using electron microscopy, we confirmed that the mesoporous TiO2 microbeads were internalized into T24 cells, and that the cell's ultrastructure was heavily compromised after UV-irradiation. In conclusion, our results show major differences in the sensitivity to UV-irradiation among the urothelial cells with respect to cell differentiation. To achieve an increased cytotoxicity of urothelial cancer cells, the photocatalytic approach is recommended.

  9. Combined cytotoxic effect of UV-irradiation and TiO2 microbeads in normal urothelial cells, low-grade and high-grade urothelial cancer cells.

    PubMed

    Imani, Roghayeh; Veranič, Peter; Iglič, Aleš; Kreft, Mateja Erdani; Pazoki, Meysam; Hudoklin, Samo

    2015-03-01

    The differentiation of urothelial cells results in normal terminally differentiated cells or by alternative pathways in low-grade or high-grade urothelial carcinomas. Treatments with traditional surgical and chemotherapeutical approaches are still inadequate and expensive, as bladder tumours are generally highly recurrent. In such situations, alternative approaches, using irradiation of the cells and nanoparticles, are promising. The ways in which urothelial cells, at different differentiation levels, respond to UV-irradiation (photolytic treatment) or to the combination of UV-irradiation and nanoparticles (photocatalytic treatment), are unknown. Here we tested cytotoxicity of UV-irradiation on (i) normal porcine urothelial cells (NPU), (ii) human low-grade urothelial cancer cells (RT4), and (iii) human high-grade urothelial cancer cells (T24). The results have shown that 1 minute of UV-irradiation is enough to kill 90% of the cells in NPU and RT4 cultures, as determined by the live/dead viability assay. On the other hand, the majority of T24 cells survived 1 minute of UV-irradiation. Moreover, even a prolonged UV-irradiation for 30 minutes killed <50% of T24 cells. When T24 cells were pre-supplemented with mesoporous TiO2 microbeads and then UV-irradiated, the viability of these high-grade urothelial cancer cells was reduced to <10%, which points to the highly efficient cytotoxic effects of TiO2 photocatalysis. Using electron microscopy, we confirmed that the mesoporous TiO2 microbeads were internalized into T24 cells, and that the cell's ultrastructure was heavily compromised after UV-irradiation. In conclusion, our results show major differences in the sensitivity to UV-irradiation among the urothelial cells with respect to cell differentiation. To achieve an increased cytotoxicity of urothelial cancer cells, the photocatalytic approach is recommended. PMID:25385056

  10. Enhancement of the photoproperties of solid-state TiO2|dye|CuI cells by coupling of two dyes

    NASA Astrophysics Data System (ADS)

    Sirimanne, P. M.; Senevirathna, M. K. I.; Premalal, E. V. A.; Pitigala, P. K. D. D. P.

    2006-06-01

    The electronic coupling of a natural pigment extracted from pomegranate fruits (rich with cyanin and exist as flavylium at natural PH) with an organic dye mercurochrome enhanced the performance of solid-state TiO2|dye|CuI-type photovoltaic cells sensitized from pomegranate pigments or mercurochrome individually.

  11. TiO2 nanoparticles cause cell damage independent of apoptosis and autophagy by impairing the ROS-scavenging system in Pichia pastoris.

    PubMed

    Liu, Zhe; Zhang, Meng; Han, Xueying; Xu, Haiming; Zhang, Biao; Yu, Qilin; Li, Mingchun

    2016-05-25

    The wide applications of titanium dioxide nanoparticles (TiO2 NPs) increase the possibility of their exposure to ecosystems, and therefore an improved understanding of their effects to organisms is required. However, their potential toxicity on eukaryotes, especially fungi, needs further detailed investigation. Here, we investigated the effects of anatase TiO2 NPs on the reactive oxygen species (ROS)-scavenging system in the model fungal organism, Pichia pastoris. Results showed that the NPs entered cells and had toxicity to this fungus, and their toxicity was attributed to cell wall damage, cell membrane damage, and ROS accumulation, but not apoptosis or autophagy. Interestingly, the synthesized TiO2 NPs impaired but not activated the ROS-scavenging system, which contributes to the cytotoxicity. Moreover, this impairment was associated with down-regulation of antioxidant-related genes, especially those genes involved in GSH regulation. Hence, GSH may play a key role in the interaction between TiO2 NPs and yeast cells. PMID:27041071

  12. Fullerene C70 decorated TiO2 nanowires for visible-light-responsive photocatalyst

    NASA Astrophysics Data System (ADS)

    Cho, Er-Chieh; Ciou, Jing-Hao; Zheng, Jia-Huei; Pan, Job; Hsiao, Yu-Sheng; Lee, Kuen-Chan; Huang, Jen-Hsien

    2015-11-01

    In this study, we have synthesized C60 and C70-modified TiO2 nanowire (NW) through interfacial chemical bonding. The results indicate that the fullerenes (C60 and C70 derivatives) can act as sinks for photogenerated electrons in TiO2, while the fullerene/TiO2 is illuminated under ultraviolet (UV) light. Therefore, in comparison to the pure TiO2 NWs, the modified TiO2 NWs display a higher photocatalytic activity under UV irradiation. Moreover, the fullerenes also can function as a sensitizer to TiO2 which expand the utilization of solar light from UV to visible light. The results reveal that the C70/TiO2 NWs show a significant photocatalytic activity for degradation of methylene blue (MB) in visible light region. To better understand the mechanism responsible for the effect of fullerenes on the photocatalytic properties of TiO2, the electron only devices and photoelectrochemical cells based on fullerenes/TiO2 are also fabricated and evaluated.

  13. Controllable atomic layer deposition of one-dimensional nanotubular TiO2

    NASA Astrophysics Data System (ADS)

    Meng, Xiangbo; Banis, Mohammad Norouzi; Geng, Dongsheng; Li, Xifei; Zhang, Yong; Li, Ruying; Abou-Rachid, Hakima; Sun, Xueliang

    2013-02-01

    This study aimed at synthesizing one-dimensional (1D) nanostructures of TiO2 using atomic layer deposition (ALD) on anodic aluminum oxide (AAO) templates and carbon nanotubes (CNTs). The precursors used are titanium tetraisopropoxide (TTIP, Ti(OCH(CH3)2)4) and deionized water. It was found that the morphologies and structural phases of as-deposited TiO2 are controllable through adjusting cycling numbers of ALD and growth temperatures. Commonly, a low temperature (150 °C) produced amorphous TiO2 while a high temperature (250 °C) led to crystalline anatase TiO2 on both AAO and CNTs. In addition, it was revealed that the deposition of TiO2 is also subject to the influences of the applied substrates. The work well demonstrated that ALD is a precise route to synthesize 1D nanostructures of TiO2. The resultant nanostructured TiO2 can be important candidates in many applications, such as water splitting, solar cells, lithium-ion batteries, and gas sensors.

  14. Solar light decomposition of DFP on the surface of anatase and rutile TiO 2 prepared by hydrothermal treatment of microemulsions

    NASA Astrophysics Data System (ADS)

    Kiselev, A.; Andersson, M.; Mattson, A.; Shchukarev, A.; Sjöberg, S.; Palmqvist, A.; Österlund, L.

    2005-06-01

    The photocatalytic decomposition of diisopropylfluorophosphate (DFP) over nanostructured anatase and rutile TiO 2 powder was investigated by FTIR and XPS. Upon irradiation with artificial solar light DFP decomposed on both polymorphs as evidenced by FTIR. For both crystalline structures acetone and subsequently coordinated formate and carbonate were observed on the surface during the photocatalytic reaction as the isopropyl groups dissociated from DFP. XPS revealed that small amounts of phosphates and inorganic fluoride (Ti sbnd F) gradually built up on both TiO 2 surfaces, while organic F was present only on the rutile phase. From repeated cycles of intermittent DFP adsorption and irradiation measurements, the decomposition rates and formation of residuals on the surface were deduced. It was found that the overall oxidation yield is higher on anatase than rutile. The oxidation rate decreases with increasing irradiation time, an effect that is more pronounced on rutile. We find that both the difference between the polymorphs and the initial decrease of the oxidation yield can largely be explained by variations in surface area rather than poisoning by PO x or F species. In particular, we observe a dramatic decrease of the specific area of rutile as a function of photocatalytic oxidation cycle.

  15. Fabrication of plasmonic AgBr/Ag nanoparticles-sensitized TiO2 nanotube arrays and their enhanced photo-conversion and photoelectrocatalytic properties

    NASA Astrophysics Data System (ADS)

    Wang, Qingyao; Qiao, Jianlei; Jin, Rencheng; Xu, Xiaohui; Gao, Shanmin

    2015-03-01

    Plasmonic photosensitizer AgBr/Ag nanospheres supported on TiO2 nanotube arrays (TiO2 NTs) are prepared by successive ionic layer adsorption and reaction (SILAR) technique followed by photoreduction methods. The structural and surface morphological properties of AgBr/Ag nanoparticles sensitized TiO2 NTs and their photoelectrochemical performance are investigated and discussed. A detailed formation mechanism of the TiO2 NTs/AgBr/Ag is proposed. The TiO2 NTs/AgBr/Ag exhibit excellent photocurrent and photoelectrocatalytic activities under visible light irradiation. Efficient utilization of solar energy to create electron-hole pairs is attributed to the significant visible light response and surface plasmon resonance of Ag nanoparticles. This finding indicates that the high photosensitivity of the TiO2 NTs-based surface plasmon resonance materials could be applied toward the development of new plasmonic visible-light-sensitive photovoltaic fuel cells and photocatalysts.

  16. Performance of Caesalpinia sappan heartwood extract as photo sensitizer for dye sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Ananth, S.; Vivek, P.; Saravana Kumar, G.; Murugakoothan, P.

    2015-02-01

    A natural dye extracted from Caesalpinia sappan heartwood was used as photo sensitizer for the first time to fabricate titanium dioxide (TiO2) nanoparticles based dye sensitized solar cells. Brazilin and brazilein are the major pigments present in the natural dye and their optimized molecular structure were calculated using Density functional theory (DFT) at 6-31G (d) level. The HOMO-LUMO were performed to reveal the energy gap using optimized structure. Pure TiO2 nanoparticles in anatase phase were synthesized by sol-gel technique. The pure and natural dye sensitized TiO2 nanoparticles were subjected to structural, optical, spectral and morphological studies. Low cost and environment friendly dye sensitized solar cells were fabricated using natural dye sensitized TiO2 based photo anode. The solar light to electron conversion efficiency of Caesalpinia sappan heartwood extract sensitized dye sensitized solar cell is 1.1%.

  17. Performance of Caesalpinia sappan heartwood extract as photo sensitizer for dye sensitized solar cells.

    PubMed

    Ananth, S; Vivek, P; Saravana Kumar, G; Murugakoothan, P

    2015-02-25

    A natural dye extracted from Caesalpinia sappan heartwood was used as photo sensitizer for the first time to fabricate titanium dioxide (TiO2) nanoparticles based dye sensitized solar cells. Brazilin and brazilein are the major pigments present in the natural dye and their optimized molecular structure were calculated using Density functional theory (DFT) at 6-31G (d) level. The HOMO-LUMO were performed to reveal the energy gap using optimized structure. Pure TiO2 nanoparticles in anatase phase were synthesized by sol-gel technique. The pure and natural dye sensitized TiO2 nanoparticles were subjected to structural, optical, spectral and morphological studies. Low cost and environment friendly dye sensitized solar cells were fabricated using natural dye sensitized TiO2 based photo anode. The solar light to electron conversion efficiency of Caesalpinia sappan heartwood extract sensitized dye sensitized solar cell is 1.1%.

  18. Supramolecular solar cells

    NASA Astrophysics Data System (ADS)

    Subbaiyan, Navaneetha Krishnan

    Supramolecular chemistry - chemistry of non-covalent bonds including different type of intermolecular interactions viz., ion-pairing, ion-dipole, dipole-dipole, hydrogen bonding, cation-pi and Van der Waals forces. Applications based on supramolecular concepts for developing catalysts, molecular wires, rectifiers, photochemical sensors have been evolved during recent years. Mimicking natural photosynthesis to build energy harvesting devices has become important for generating energy and solar fuels that could be stored for future use. In this dissertation, supramolecular chemistry is being explored for creating light energy harvesting devices. Photosensitization of semiconductor metal oxide nanoparticles, such as titanium dioxide (TiO2) and tin oxide (SnO2,), via host-guest binding approach has been explored. In the first part, self-assembly of different porphyrin macrocyclic compounds on TiO2 layer using axial coordination approach is explored. Supramolecular dye sensitized solar cells built based on this approach exhibited Incident Photon Conversion Efficiency (IPCE) of 36% for a porphyrin-ferrocene dyad. In the second part, surface modification of SnO2 with water soluble porphyrins and phthalocyanine resulted in successful self-assembly of dimers on SnO2 surface. IPCE more than 50% from 400 - 700 nm is achieved for the supramolecular self-assembled heterodimer photocells is achieved. In summary, the axial ligation and ion-pairing method used as supramolecular tools to build photocells, exhibited highest quantum efficiency of light energy conversion with panchromatic spectral coverage. The reported findings could be applied to create interacting molecular systems for next generation of efficient solar energy harvesting devices.

  19. Synthesis and characterization of Pt-MoO x -TiO2 electrodes for direct ethanol fuel cells

    NASA Astrophysics Data System (ADS)

    Wang, Xiu-Yu; Zhang, Jing-Chang; Cao, Xu-Dong; Jiang, Yuan-Sheng; Zhu, Hong

    2011-10-01

    To enhance the CO-tolerance performance of anode catalysts for direct ethanol fuel cells, carbon nanotubes were modified by titanium dioxide (donated as CNTs@TiO2) and subsequently served as the support for the preparation of Pt/CNTs@TiO2 and Pt-Mo/CNTs@TiO2 electrocatalysts via a UV-photoreduction method. The physicochemical characterizations of the catalysts were carried out by using X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and infrared spectroscopy of adsorbed probe ammonia molecules. The electrocatalytic properties of the catalysts for methanol oxidation were investigated by the cyclic voltammetry technique. The results show that Pt-Mo/CNTs@TiO2 electrode exhibits the highest performance in all the electrodes. It is explained that, the structure, the oxidation states, and the acid-base properties of the catalysts are influenced due to the strong interaction between Ti and Mo species by adding TiO2 and MoO x to the Pt-based catalysts.

  20. TiO2 nanotubes as drug nanoreservoirs for the regulation of mobility and differentiation of mesenchymal stem cells.

    PubMed

    Hu, Yan; Cai, Kaiyong; Luo, Zhong; Xu, Dawei; Xie, Daichao; Huang, Yuran; Yang, Weihu; Liu, Peng

    2012-01-01

    The extracellular microenvironment plays a key role in the regulation of cellular behavior. To mimic the natural extracellular microenvironment, TiO(2) nanotube (TNT) arrays as drug nanoreservoirs for loading of bone morphogenetic protein 2 (BMP2) were constructed on titanium substrates and then covered with multilayered coatings of gelatin/chitosan (Gel/Chi) for controlled drug release. The multilayered coatings were constructed via a spin-assisted layer-by-layer assembly technique. The successful fabrication of this system was monitored by field emission scanning electron microscopy, atomic force microscopy, X-ray photoelectron spectroscopy and contact angle measurements. Multilayered coating with Gel/Chi retained the drug bioactivity and release properties, which were revealed by superoxide dismutase activity measurement. In addition, cytoskeleton observation and wound healing assay confirmed that BMP2-loaded and multilayer-coated TNT arrays were able to stimulate motogenic responses of mesenchymal stem cells (MSCs). More importantly, the system demonstrated that it was capable of promoting the osteoblastic differentiation of MSCs. This study may have potential impact on the development of bone implants for enhanced bone osseointegration.