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1

Dye-sensitized TiO2 nanotube solar cells: rational structural and surface engineering on TiO2 nanotubes.  

PubMed

Owing to well-defined structural parameters and enhanced electronic properties, highly ordered TiO(2) nanotube arrays have been employed to substitute TiO(2) nanoparticles for use in dye-sensitized solar cells. To further improve the performance of dye-sensitized TiO(2) nanotube solar cells, efforts have been directed toward the optimization of TiO(2) photoanodes, dyes, electrolytes, and counter electrodes. Herein, we highlight recent progress in rational structural and surface engineering on anodic TiO(2) nanotube arrays and their effects on improving the power conversion efficiency of dye-sensitized TiO(2) nanotube solar cells. PMID:22711337

Wang, Jun; Lin, Zhiqun

2012-12-01

2

Fabrication of dye sensitized solar cell using TiO 2 coated carbon nanotubes  

Microsoft Academic Search

We fabricated a dye sensitized solar cells (DSCs) using TiO2 coated multi-wall carbon nanotubes (TiO2-CNTs). Carbon nanotubes (CNTs) have excellent electrical conductivity and good chemical stability. We introduced CNTs in DSCs to improve solar cell performance through reduction of series resistance. TiO2-CNTs were obtained by Sol–Gel method. Compared with a conventional TiO2 cell, the TiO2-CNTs content (0.1 wt.%) cell showed ?50%

Tae Young Lee; P. S. Alegaonkar; Ji-Beom Yoo

2007-01-01

3

Systematic investigation of the role of compact TiO 2 layer in solid state dye-sensitized TiO 2 solar cells  

Microsoft Academic Search

The preparation steps of solid state dye-sensitized nanocrystalline TiO2 solar cells are optimized with respect to the blocking TiO2 layer which is one of the essential layers in such a multi-layer solar cell. By varying the number of spraying cycles in the preparation of the blocking TiO2 films, a series of samples with increasing blocking layer thicknesses was prepared. Influence

Bin Peng; Gert Jungmann; Claus Jäger; Dietrich Haarer; Hans-Werner Schmidt; Mukundan Thelakkat

2004-01-01

4

Perovskite Solar Cell with an Efficient TiO2 Compact Film.  

PubMed

A perovskite solar cell with a thin TiO2 compact film prepared by thermal oxidation of sputtered Ti film achieved a high efficiency of 15.07%. The thin TiO2 film prepared by thermal oxidation is very dense and inhibits the recombination process at the interface. The optimum thickness of the TiO2 compact film prepared by thermal oxidation is thinner than that prepared by spin-coating method. Also, the TiO2 compact film and the TiO2 porous film can be sintered at the same time. This one-step sintering process leads to a lower dark current density, a lower series resistance, and a higher recombination resistance than those of two-step sintering. Therefore, the perovskite solar cell with the TiO2 compact film prepared by thermal oxidation has a higher short-circuit current density and a higher fill factor. PMID:25166513

Ke, Weijun; Fang, Guojia; Wang, Jing; Qin, Pingli; Tao, Hong; Lei, Hongwei; Liu, Qin; Dai, Xin; Zhao, Xingzhong

2014-09-24

5

Dynamic preparation of TiO 2 films for fabrication of dye-sensitized solar cells  

Microsoft Academic Search

Preparation of nanocrystalline porous titanium dioxide (TiO2) films with roll-to-roll compatible methods was studied. Gravure printing was used for spreading TiO2 paste and paper calendering for pressing TiO2 nanoparticle films. Influence of different preparation methods on performance of fabricated dye-sensitized solar cells (DSSCs) was investigated. The attained light into electricity conversion efficiency was compared with DSSCs fabricated on conductive plastic

Henriette Santa-Nokki; Jani Kallioinen; Terho Kololuoma; Vladimir Tuboltsev; Jouko Korppi-Tommola

2006-01-01

6

Optimization of the structure nanoporous TiO2 film in a dye- sensitized solar cell  

NASA Astrophysics Data System (ADS)

The numerical model of dye-sensitized solar cell based on TiO2 presented here allow to construct the theoretical I-V characteristics, determine the photovoltaic parameters and obtain important information about the main factors that influence DSSC performance. For modeling of solar cell was considered system of one-dimensional differential continuity equations, describing the charge transfer in its structure. The simulated results allow to determine the optimal TiO2 particle diameter (radius), thickness, porosity and topological dimensions TiO2 film.

Malyukov, S. P.; Kulikova, I. V.; Sayenko, A. V.; Klunnikova, Yu V.

2014-10-01

7

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

PubMed

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

Dadgostar, Shabnam; Tajabadi, Fariba; Taghavinia, Nima

2012-06-27

8

Hydrogenated TiO2 film for enhancing photovoltaic properties of solar cells and self-sensitized effect  

NASA Astrophysics Data System (ADS)

Hydrogenated TiO2 film was obtained by annealing TiO2 film at 350 °C for 2 h with hydrogen, and TiO2 films were prepared by screen printing on fluorine-doped tin oxide glass. Structural characterization by X-ray diffraction and electron microscopy did not show obvious difference between hydrogenated TiO2 film and pristine TiO2 film. Through optical and electrochemical characterization, the hydrogenated TiO2 film showed enhanced absorption and narrowed band gap, as well as reduced TiO2 surface impedance and dark current. As a result, an obviously enhanced photovoltaic effect was observed in the solar cell with hydrogenated TiO2 as photoanode without adding any dye due to the self-sensitized effect of hydrogenated TiO2 film, which excited electrons injecting internal conduction band of TiO2 to generate more photocurrent.

He, Hongcai; Yang, Kui; Wang, Ning; Luo, Feifei; Chen, Haijun

2013-12-01

9

Electrolyte/photoanode engineered performance of TiO2 based dye sensitised solar cells  

NASA Astrophysics Data System (ADS)

The performance of dye sensitized solar cells (DSSCs) depends on the collective contribution from its constituents which include the nanoparticle film, dye, electrolyte, and the counter electrode. In this report, we have tried to elucidate the varying performance of the TiO2 based DSSCs standardised using N719 dye and Platinum as counter electrode with various electrolytes including quasi static electrolytes. We have also evaluated the photovoltaic characteristics of the cells employing different morphological structured TiO2 photoanode. The DSSC based on the hierarchical anatase TiO2 nanotree photoelectrode showed the highest light-to-electricity conversion efficiency of 10.2%.

Divya, S.; Thankappan, Aparna; Vallabhan, C. P. G.; Nampoori, V. P. N.; Radhakrishnan, P.; Mujeeb, A.

2014-02-01

10

Inverted organic solar cells based on Cd-doped TiO2 as an electron extraction layer  

NASA Astrophysics Data System (ADS)

Nanocrystalline Cd-doped TiO2 thin films have been prepared by sol-gel method. X-ray diffraction analysis reveals that TiO2 and Cd-doped TiO2 nanocrystalline thin films are of anatase phase. The average grain size of TiO2 and Cd-doped TiO2 nanocrystalline thin films was found to lie in the range of 15-18 nm. Solar cells have been fabricated with a device structure of ITO/Cd-doped TiO2/P3HT:PC71BM/MoO3/Al configuration. The power conversion efficiency of the inverted organic solar cell with Cd-doped TiO2 is 3.06% and is higher than that of TiO2 based organic solar cell (2.64%).

Ranjitha, A.; Muthukumarasamy, N.; Thambidurai, M.; Velauthapillai, Dhayalan; Madhan Kumar, A.; Gasem, Zuhair M.

2014-10-01

11

N-Ion-implanted TiO2 photoanodes in quantum dot-sensitized solar cells  

NASA Astrophysics Data System (ADS)

Hierarchical nanostructured titanium dioxide (TiO2) clumps were fabricated using electrostatic spray with subsequent nitrogen-ion doping by an ion-implantation technique for improvement of energy conversion efficiency for quantum dot-sensitized solar cells (QDSCs). CdSe quantum dots were directly assembled on the produced N-ion-implanted TiO2 photoanodes by chemical bath deposition, and their photovoltaic performance was evaluated in a polysulfide electrolyte with a Pt counter electrode. We found that the photovoltaic performance of TiO2 electrodes was improved by nearly 145% upon N-ion implantation. The efficiency improvement seems to be due to (1) the enhancement of electron transport through the TiO2 layer by inter-particle necking of primary TiO2 particles and (2) an increase in the recombination resistance at TiO2/QD/electrolyte interfaces by healing the surface states or managing the oxygen vacancies upon N-ion doping. Therefore, N-ion-doped photoanodes offer a viable pathway to develop more efficient QD or dye-sensitized solar cells.Hierarchical nanostructured titanium dioxide (TiO2) clumps were fabricated using electrostatic spray with subsequent nitrogen-ion doping by an ion-implantation technique for improvement of energy conversion efficiency for quantum dot-sensitized solar cells (QDSCs). CdSe quantum dots were directly assembled on the produced N-ion-implanted TiO2 photoanodes by chemical bath deposition, and their photovoltaic performance was evaluated in a polysulfide electrolyte with a Pt counter electrode. We found that the photovoltaic performance of TiO2 electrodes was improved by nearly 145% upon N-ion implantation. The efficiency improvement seems to be due to (1) the enhancement of electron transport through the TiO2 layer by inter-particle necking of primary TiO2 particles and (2) an increase in the recombination resistance at TiO2/QD/electrolyte interfaces by healing the surface states or managing the oxygen vacancies upon N-ion doping. Therefore, N-ion-doped photoanodes offer a viable pathway to develop more efficient QD or dye-sensitized solar cells. Electronic supplementary information (ESI) available: Details of SRIM 2008 simulation, optical absorption, and Bode plots. See DOI: 10.1039/c2nr11953f

Sudhagar, P.; Asokan, K.; Ito, E.; Kang, Yong Soo

2012-03-01

12

Fabrication of Grätzel solar cell with TiO 2\\/CdS bilayered photoelectrode  

Microsoft Academic Search

In this investigation, cadmium sulfide (CdS)-sensitized stable Grätzel solar cell has been fabricated, where nano-crystalline titanium oxide (TiO2) photoelectrode has been deposited on SnO2:F coated glass substrate by facing target reactive sputtering technique and CdS sensitizing layer has been deposited by chemical bath deposition technique. The X-ray diffraction measurement reveals that both the TiO2 and CdS layer show polycrystalline nature.

S. Biswas; M. F. Hossain; T. Takahashi

2008-01-01

13

Fabrication of dye-sensitized solar cells by transplanting highly ordered TiO 2 nanotube arrays  

Microsoft Academic Search

Highly ordered TiO2 nanotube arrays fabricated by anodization are very attractive to dye-sensitized solar cells (DSCs) due to their superior charge percolation and slower charge recombination. However, the efficiency of TiO2-nanotube-based DSCs is 6.89%, which is still lower than that of TiO2-nanoparticle-based DSCs. We have suggested the transplanting the highly ordered TiO2 nanotube arrays to FTO glass to improve the

Hun Park; Woong-Rae Kim; Hyo-Tae Jeong; Jae-Joon Lee; Ho-Gi Kim; Won-Youl Choi

2011-01-01

14

Silver-coated TiO2 electrodes for high performance dye-sensitized solar cells  

NASA Astrophysics Data System (ADS)

Silver-coated TiO2 electrodes were prepared by photodeposition with different light durations. Comparing with the dye-sensitized solar cells (DSSCs) using conventional TiO2 electrode, the conversion efficiency of DSSCs fabricated with silver-coated TiO2 electrodes was improved from 5.97% to 6.86%. The Ag layer could reflect incident light and lengthen the optical path in electrodes, and also appropriate Ag particles absorbed on the TiO2 surface slowed down the electron recombination. The recombination mechanisms of DSSCs were analyzed by open circuit voltage decay (OCVD) measurements, which provide evidence that the charge transfer from the surface state was strongly suppressed by the silver coating.

Peng, Wei; Zeng, Yun; Gong, Hao; Leng, Yong-qing; Yan, Yong-hong; Hu, Wei

2013-11-01

15

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

PubMed

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. PMID:17214486

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

16

Preparation and characterization of TiO2 barrier layers for dye-sensitized solar cells.  

PubMed

A TiO2 barrier layer is critical in enhancing the performance of dye-sensitized solar cells (DSSCs). Two methods to prepare the TiO2 barrier layer on fluorine-doped tin dioxide (FTO) surface were systematically studied in order to minimize electron-hole recombination and electron backflow during photovoltaic processes of DSSCs. The film structure and materials properties were correlated with the photovoltaic characteristics and electrochemical properties. In the first approach, a porous TiO2 layer was deposited by wet chemical treatment of the sample with TiCl4 solution for time periods varying from 0 to 60 min. The N719 dye molecules were found to be able to insert into the porous barrier layers. The 20 min treatment formed a nonuniform but intact TiO2 layer of ?100-300 nm in thickness, which gave the highest open-circuit voltage VOC, short-circuit photocurrent density JSC, and energy conversion efficiency. But thicker TiO2 barrier layers by this method caused a decrease in JSC, possibly limited by lower electrical conductance. In the second approach, a compact TiO2 barrier layer was created by sputter-coating 0-15 nm Ti metal films on FTO/glass and then oxidizing them into TiO2 with thermal treatment at 500 °C in the air for 30 min. The dye molecules were found to only attach at the outer surface of the barrier layer and slightly increased with the layer thickness. These two kinds of barrier layer showed different characteristics and may be tailored for different DSSC studies. PMID:24927111

Zheng, Yichen; Klankowski, Steven; Yang, Yiqun; Li, Jun

2014-07-01

17

Easily manufactured TiO2 hollow fibers for quantum dot sensitized solar cells.  

PubMed

TiO(2) hollow fibers with high surface area were manufactured by a simple synthesis method, using natural cellulose fibers as template. The effective light scattering properties of the hollow fibers, originating from their micron size, were observed by diffuse reflectance spectroscopy. In spite of the micrometric length of the TiO(2) hollow fibers, the walls were highly porous and high surface area (78.2 m(2) g(-1)) was obtained by the BET method. TiO(2) hollow fibers alone and mixed with other TiO(2) pastes were sensitized with CdSe quantum dots (QDs) by Successive Ionic Layer Adsorption and Reaction (SILAR) and integrated as a photoanode in quantum dot sensitized solar cells (QDSCs). High power conversion efficiency was obtained, 3.24% (V(oc) = 503 mV, J(sc) = 11.92 mA cm(-2), FF = 0.54), and a clear correspondence of the cell performance with the photoanode structure was observed. The unique properties of these fibers: high surface area, effective light scattering, hollow structure to facile electrolyte diffusion and the rather high efficiencies obtained here suggest that hollow fibers can be introduced as promising nanostructures to make highly efficient quantum dot sensitized solar cells. PMID:22108763

Samadpour, Mahmoud; Giménez, Sixto; Zad, Azam Iraji; Taghavinia, Nima; Mora-Seró, Iván

2012-01-14

18

Preparation of flexible TiO2 photoelectrodes for dye-sensitized solar cells  

NASA Astrophysics Data System (ADS)

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.

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

2014-09-01

19

High efficiency electrospun TiO2 nanofiber based hybrid organic-inorganic perovskite solar cell  

NASA Astrophysics Data System (ADS)

The good electrical and morphological characteristics of TiO2 nanofibers and the high extinction coefficient of CH3NH3PbI3 perovskite are combined to obtain a solar cell with a power conversion efficiency of 9.8%. The increase of the film thickness dramatically diminishes the performance due to the reduction in porosity of the TiO2 nanofiber framework. The optimum device (~413 nm film thickness) is compared to a planar device, where the latter produces higher Voc but lower Jsc, and consequently lower efficiency at all measured light intensities.The good electrical and morphological characteristics of TiO2 nanofibers and the high extinction coefficient of CH3NH3PbI3 perovskite are combined to obtain a solar cell with a power conversion efficiency of 9.8%. The increase of the film thickness dramatically diminishes the performance due to the reduction in porosity of the TiO2 nanofiber framework. The optimum device (~413 nm film thickness) is compared to a planar device, where the latter produces higher Voc but lower Jsc, and consequently lower efficiency at all measured light intensities. Electronic supplementary information (ESI) available. See DOI: 10.1039/c3nr04857h

Dharani, Sabba; Mulmudi, Hemant Kumar; Yantara, Natalia; Thu Trang, Pham Thi; Park, Nam Gyu; Graetzel, Michael; Mhaisalkar, Subodh; Mathews, Nripan; Boix, Pablo P.

2014-01-01

20

Annealing effect on Sb2S3-TiO2 nanostructures for solar cell applications  

NASA Astrophysics Data System (ADS)

Nanostructures composited of vertical rutile TiO2 nanorod arrays and Sb2S3 nanoparticles were prepared on an F:SnO2 conductive glass by hydrothermal method and successive ionic layer adsorption and reaction method at low temperature. Sb2S3-sensitized TiO2 nanorod solar cells were assembled using the Sb2S3-TiO2 nanostructure as the photoanode and a polysulfide solution as an electrolyte. Annealing effects on the optical and photovoltaic properties of Sb2S3-TiO2 nanostructure were studied systematically. As the annealing temperatures increased, a regular red shift of the bandgap of Sb2S3 nanoparticles was observed, where the bandgap decreased from 2.25 to 1.73 eV. At the same time, the photovoltaic conversion efficiency for the nanostructured solar cells increased from 0.46% up to 1.47% as a consequence of the annealing effect. This improvement can be explained by considering the changes in the morphology, the crystalline quality, and the optical properties caused by the annealing treatment.

Li, Yitan; Wei, Lin; Zhang, Ruizi; Chen, Yanxue; Mei, Liangmo; Jiao, Jun

2013-02-01

21

Cascade structure of TiO 2\\/ZnO\\/CdS film for quantum dot sensitized solar cells  

Microsoft Academic Search

Quantum dot sensitized solar cells based on cascade structure of TiO2\\/ZnO\\/CdS electrode and polysulfide electrolyte were fabricated. The ZnO layer was deposited on screen-printed TiO2 layer by ultrasonic spray pyrolysis method. The structure, morphology and impedance of TiO2\\/ZnO film photoanode and the photovoltaic performance of TiO2\\/ZnO\\/CdS cell were investigated. It is found that the short circuit current density and conversion

Guang Zhu; Likun Pan; Tao Xu; Qingfei Zhao; Zhuo Sun

2011-01-01

22

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

NASA Astrophysics Data System (ADS)

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

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

23

Quasi-solid dye-sensitized solar cells: control of TiO2-gel electrolyte interfaces  

NASA Astrophysics Data System (ADS)

Quasi-solid dye sensitized solar cells (Q-DSSC) were fabricated by employing gel electrolytes containing ionic liquids and gelators. Sufficient physical contacts between nano-crystalline TiO2 particles and gel electrolytes in nano-porous TiO2 layers were achieved by solidifying gel electrolyte precursors after the cells are filled with the electrolytes. Photo-currents increased largely by embedding carboxylic acids among dye molecules on TiO2 crystals. The nano-porous TiO2 electrolytes were fabricated by dipping the dye anchored TiO2 substrates in dilute solutions of carboxylic acids. It was found that resistances in the TiO2 layers decreased by these treatments.

Hayase, Shuzi; Kato, Takehito; Kado, Takashi; Sakaguchi, Shohei; Ueki, Hirotaka; Takashima, Wataru; Kaneto, Keiichi; Shiratuchi, Ryuichi; Sumino, Hiroyasu; Murai, Shinji; Mikoshiba, Satoshi

2004-02-01

24

Facile synthesis of TiO2 inverse opal electrodes for dye-sensitized solar cells.  

PubMed

Engineering of TiO(2) electrode layers is critical to guaranteeing the photoconversion efficiency of dye-sensitized solar cells (DSSCs). Recently, a novel approach has been introduced for producing TiO(2) electrodes using the inverted structures of colloidal crystals. This paper describes a facile route to producing ordered macroporous electrodes from colloidal crystal templates for DSSCs. Using concentrated colloids dispersed in a volatile medium, the colloidal crystal templates were obtained within a few minutes, and the thickness of the template was easily controlled by changing the quantity of colloidal solution deposited. Here, the effects of the structural properties of the inverse opal TiO(2) electrodes on the photovoltaic parameters of DSSCs were investigated. The photovoltaic parameters were measured as a function of pore ordering and electrode film thickness. Moreover, DSSC applications that used either liquid or viscous polymer electrolyte solutions were investigated to reveal the effects of pore size on performance of an inverse opal TiO(2) electrode. PMID:21155579

Shin, Ju-Hwan; Kang, Ji-Hwan; Jin, Woo-Min; Park, Jong Hyeok; Cho, Young-Sang; Moon, Jun Hyuk

2011-01-18

25

TiO2-nanotube-based dye-sensitized solar cells containing fluorescent material.  

PubMed

We fabricated a dye-sensitized solar cells (DSCs) with TiO2 nanotube arrays obtained by anodization of Ti foil. Vertical structure of TiO2 nanotube arrays is very attractive due to a high electron transfer from dye to electrode. To improve the power conversion efficiency, fluorescent material, F-6377, was applied in TiO2-nanotube-based DSCs to use a light spectrum efficiently. Fluorescent material was absorbed the different wavelength of 460 nm from the light absorbed by N719 dye. Fluorescent material to emit the absorbed light energy provided an additional light for dye in DSCs and additional electrons was generated. Thickness of TiO2 nanotube arrays grown by anodic oxidation was 15 microm. N719 dye and 13(-)/l(-) electrolyte were used to fabricate the DSCs. The short circuit current densities (J(sc)) and the power conversion efficiency in DSCs with fluorescent were 10.8 mA/cm2 and 2.48%, respectively. Electrochemical impedance spectroscopy (EIS) was observed to understand an electron transfer and life time. PMID:23858885

Kim, Woong-Rae; Lee, Young-Joon; Park, Hun; Lee, Jae-Joon; Choi, Won-Youl

2013-05-01

26

Aqueous coating of efficient flexible TiO 2 dye solar cell photoanodes  

Microsoft Academic Search

We describe the preparation and characterization of flexible TiO2 photoanodes coated on indium tin oxide–polyethylene naphthalate (ITO–PEN) substrates from aqueous solutions. We find that the use of hexafluorosalisilic acid promotes low-temperature connection of the TiO2 nanoparticles, considerably increasing the solar conversion efficiency. In addition, we report that highly dispersed TiO2 nanocrystals improve adhesion to the substrate, while micron-size aggregates improve

Aurelien Du Pasquier; Mattew Stewart; Timothy Spitler; Mike Coleman

2009-01-01

27

Quantitative electron tomography investigation of a TiO2 based solar cell photoanode  

NASA Astrophysics Data System (ADS)

The development of efficient thin film solar cells requires a deep knowledge of the nanoscale morphology of the active layers. While conventional investigation is usually limited to 2D information, here we use electron tomography to unravel a complex particle network in a non-ambiguous, 3D reconstruction. We present our study of a dye sensitised solar cell, based on a nanostructured TiO2 photoanode produced by pulsed laser deposition (PLD) and displaying a hierarchical, quasi-1D arrangement. We prepare the sample for electron tomography using focused ion beam (FIB) milling to obtain a micro-pillar, instead of a conventional TEM lamella. This approach has the advantage of allowing higher quality tomographic reconstructions of complex morphologies due to the increased tilt range available and the constant thickness of the section. We analyse the resulting reconstruction to quantitatively investigate the geometry of the TiO2 network. We compare the findings with a photoanode based on a conventional TiO2 paste, determining the anisotropy of the PLD-grown film. To complement our nanoscale TEM characterization, we also employ FIB tomography, to obtain a complete structural characterisation of the photoanode at different length scales.

Divitini, G.; Abrusci, A.; Di Fonzo, F.; Snaith, H.; Ducati, C.

2014-06-01

28

Mesoscopic CH3NH3PbI3/TiO2 heterojunction solar cells.  

PubMed

We report for the first time on a hole conductor-free mesoscopic methylammonium lead iodide (CH(3)NH(3)PbI(3)) perovskite/TiO(2) heterojunction solar cell, produced by deposition of perovskite nanoparticles from a solution of CH(3)NH(3)I and PbI(2) in ?-butyrolactone on a 400 nm thick film of TiO(2) (anatase) nanosheets exposing (001) facets. A gold film was evaporated on top of the CH(3)NH(3)PbI(3) as a back contact. Importantly, the CH(3)NH(3)PbI(3) nanoparticles assume here simultaneously the roles of both light harvester and hole conductor, rendering superfluous the use of an additional hole transporting material. The simple mesoscopic CH(3)NH(3)PbI(3)/TiO(2) heterojunction solar cell shows impressive photovoltaic performance, with short-circuit photocurrent J(sc)= 16.1 mA/cm(2), open-circuit photovoltage V(oc) = 0.631 V, and a fill factor FF = 0.57, corresponding to a light to electric power conversion efficiency (PCE) of 5.5% under standard AM 1.5 solar light of 1000 W/m(2) intensity. At a lower light intensity of 100W/m(2), a PCE of 7.3% was measured. The advent of such simple solution-processed mesoscopic heterojunction solar cells paves the way to realize low-cost, high-efficiency solar cells. PMID:23043296

Etgar, Lioz; Gao, Peng; Xue, Zhaosheng; Peng, Qin; Chandiran, Aravind Kumar; Liu, Bin; Nazeeruddin, Md K; Grätzel, Michael

2012-10-24

29

Aggregated TiO2 Based Nanotubes for Dye Sensitized Solar Cells  

SciTech Connect

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.

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

2013-11-01

30

Performance and electron transport properties of TiO2 nanocomposite dye-sensitized solar cells  

NASA Astrophysics Data System (ADS)

TiO2 nanowire (NW)/nanoparticle (NP) composite films have been fabricated by hybridizing various ratios of hydrothermal anatase NWs and TiO2 NPs for use in dye-sensitized solar cells (DSSCs). Scanning electron microscopy (SEM) images reveal that uniform NW/NP composite films were formed on fluorine-doped tin oxide (FTO) substrates by the dip-coating method. The NWs are randomly but neither vertically nor horizontally oriented within the composite film. The TiO2 NP DSSC possesses superior performance to those of the NW/NP composite and the pure NW cells, and the efficiency of the NW/NP composite DSSC increases on increasing the NP/NW ratio in the composite anode. All types of DSSC possess the same dependence of performance on the anode thickness that the efficiency increases with the anode thickness to a maximum value, then it decreases when the anode is thickened further. Electrochemical impedance spectroscopy analyses reveal that the NP DSSCs possess larger effective electron diffusion coefficients (Deff) in the photoanodes and smaller diffusion resistances of I3- in electrolytes compared to those in the NW/NP and the NW DSSCs. Deff decreases when NWs are added into the photoanode. These results suggest that the vertical feature of the NWs within the anodes is crucial for achieving a high electron transport rate in the anode.

Wu, Jih-Jen; Chen, Guan-Ren; Lu, Chia-Chun; Wu, Wei-Ting; Chen, Jen-Sue

2008-03-01

31

Hydrothermal Fabrication of Hierarchically Anatase TiO2 Nanowire arrays on FTO Glass for Dye-sensitized Solar Cells  

PubMed Central

Hierarchical anatase TiO2 nano-architecture arrays consisting of long TiO2 nanowire trunk and numerous short TiO2 nanorod branches on transparent conductive fluorine-doped tin oxide glass are successfully synthesized for the first time through a facile one-step hydrothermal route without any surfactant and template. Dye-sensitized solar cells based on the hierarchical anatase TiO2 nano-architecture array photoelectrode of 18??m in length shows a power conversion efficiency of 7.34% because of its higher specific surface area for adsorbing more dye molecules and superior light scattering capacity for boosting the light-harvesting efficiency. The present photovoltaic performance is the highest value for the reported TiO2 nanowires array photoelectrode. PMID:23443301

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

2013-01-01

32

A 4.2% efficient flexible dye-sensitized TiO 2 solar cells using stainless steel substrate  

Microsoft Academic Search

An efficient flexible dye-sensitized solar cells (DSSCs) using stainless steel supporting substrate for fabricating nanocrystalline TiO2 film electrodes were developed, intending to improve the photoelectrochemical properties of plastic substrate-based DSSCs. The most important advantage of a stainless steel-based TiO2 film electrode over a plastic-based electrode lies in its high-temperature sinterability. Optimal photovoltaic properties were obtained with a cell where the

Man Gu Kang; Nam-Gyu Park; Kwang Sun Ryu; Soon Ho Chang; Kang-Jin Kim

2006-01-01

33

Al2O3 Doping of TiO2 electrodes and applications in dye-sensitized solar cells  

NASA Astrophysics Data System (ADS)

Dye-sensitized solar cells (DSSCs) have been intensively studied since their discovery in 1991. DSSCs have been extensively researched over the past decades as cheaper alternatives to silicon solar cells due to their high energy-conversion efficiency and their low production cost. However, some problems need to be solved in order to enhance the efficiency of DSSCs. In particular, the electron recombination that occurs due to the contact between the transparent conductive oxide (TCO) and a redox electrolyte is one of the main limiting factors of efficiency. In this work, we report for the first time the improvement of the photovoltaic characteristics of DSSCs by doping TiO2 with Al2O3. DSSCs were constructed using composite particles of Al2O3-doped TiO2 and TiO2 nanoparticles. The DSSCs using Al2O3 showed the maximum conversion efficiency of 6.29% due to effective electron transport. DSSCs based on Al2O3-doped TiO2 films showed better photovoltaic performance than cells fabricated with only TiO2 nanoparticles. This result is attributed to the prevention of electron recombination between electrons in the TiO2 conduction band with holes in the dye or the electrolyte. There mechanism is suggested based on impedance results, which indicated improved electron transport at the TiO2/dye/electrolyte interface.

Eom, Tae Sung; Kim, Kyung Hwan; Bark, Chung Wung; Choi, Hyung Wook

2014-08-01

34

Application of TiO2 nanoparticles coated multi-wall carbon nanotube to dye-sensitized solar cells.  

PubMed

This study uses the sol-gel method to prepare TiO2 nanoparticle, and further applies TiO2 nanoparticle coating on the surface of the multi-wall carbon nanotube (MWCNT). As a result, TiO2-CNT composite nanoparticles are prepared to serve as photoelectrode material in dye-sensitized solar cell (DSSC). First, after acid treatment of MWCNT is used to remove impurities. Then, the sol-gel method is employed to prepare TiO2-CNT composite nanopowder. X-ray diffraction (XRD) pattern shows that after the TiO2 in TiO2-CNT composite nanopowder has been thermally treated at 450 degrees C, it can be completely changed to anatase phase. Furthermore, as shown from the SEM image, TiO2 has been successfully coated on CNT. The photoelectrode of DSSC is prepared using the electrophoretic deposition method (EPD) to mix the Degassa P25 TiO2 nanoparticles with TiO2-CNT powder for deposition on the indium tin oxide (ITO) conductive glass. After secondary EPD, a thin film of TiO2/CNTs with thickness 17 microm can be acquired. For the prepared TiO2-CNT composite nanoparticles, since MWCNT can increase the short-circuit current density of DSSC, the light-to-electricity conversion efficiency of DSSC can be effectively increased. Experimental results show that the photoelectric conversion efficiency of DSSC using CNT/TiO2 photoelectrode and N719 dye is increased by 41% from the original 3.45% to 4.87%. PMID:21138007

Chang, Ho; Kao, Mu-Jung; Huang, Kuohsiu-David; Hsieh, Tung-Jung; Chien, Shu-Hua

2010-11-01

35

TiO2 micro-flowers composed of nanotubes and their application to dye-sensitized solar cells.  

PubMed

TiO2 micro-flowers were made to bloom on Ti foil by the anodic oxidation of Ti-protruding dots with a cylindrical shape. Arrays of the Ti-protruding dots were prepared by photolithography, which consisted of coating the photoresists, attaching a patterned mask, illuminating with UV light, etching the Ti surface by reactive ion etching (RIE), and stripping the photoresist on the Ti foil. The procedure for the blooming of the TiO2 micro-flowers was analyzed by field emission scanning electron microscopy (FESEM) as the anodizing time was increased. Photoelectrodes of dye-sensitized solar cells (DSCs) were fabricated using TiO2 micro-flowers. Bare TiO2 nanotube arrays were used for reference samples. The short-circuit current (Jsc) and the power conversion efficiency of the DSCs based on the TiO2 micro-flowers were 4.340 mA/cm2 and 1.517%, respectively. These values of DSCs based on TiO2 micro-flowers were higher than those of bare samples. The TiO2 micro-flowers had a larger surface area for dye adsorption compared to bare TiO2 nanotube arrays, resulting in improved Jsc characteristics. The structure of the TiO2 micro-flowers allowed it to adsorb dyes very effectively, also demonstrating the potential to achieve higher power conversion efficiency levels for DSCs compared to a bare TiO2 nanotube array structure and the conventional TiO2 nanoparticle structure. PMID:24565201

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

2014-01-01

36

TiO2 micro-flowers composed of nanotubes and their application to dye-sensitized solar cells  

PubMed Central

TiO2 micro-flowers were made to bloom on Ti foil by the anodic oxidation of Ti-protruding dots with a cylindrical shape. Arrays of the Ti-protruding dots were prepared by photolithography, which consisted of coating the photoresists, attaching a patterned mask, illuminating with UV light, etching the Ti surface by reactive ion etching (RIE), and stripping the photoresist on the Ti foil. The procedure for the blooming of the TiO2 micro-flowers was analyzed by field emission scanning electron microscopy (FESEM) as the anodizing time was increased. Photoelectrodes of dye-sensitized solar cells (DSCs) were fabricated using TiO2 micro-flowers. Bare TiO2 nanotube arrays were used for reference samples. The short-circuit current (Jsc) and the power conversion efficiency of the DSCs based on the TiO2 micro-flowers were 4.340 mA/cm2 and 1.517%, respectively. These values of DSCs based on TiO2 micro-flowers were higher than those of bare samples. The TiO2 micro-flowers had a larger surface area for dye adsorption compared to bare TiO2 nanotube arrays, resulting in improved Jsc characteristics. The structure of the TiO2 micro-flowers allowed it to adsorb dyes very effectively, also demonstrating the potential to achieve higher power conversion efficiency levels for DSCs compared to a bare TiO2 nanotube array structure and the conventional TiO2 nanoparticle structure. PMID:24565201

2014-01-01

37

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

PubMed Central

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

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

2013-01-01

38

Multi-functionality of macroporous TiO2 spheres in dye-sensitized and hybrid heterojunction solar cells.  

PubMed

Micron-sized macroporous TiO2 spheres (MAC-TiO2) were synthesized using a colloidal templating process inside emulsions, which were then coated on a nanocrystalline TiO2 light absorption film to prepare a bilayered photoanode for liquid-based dye-sensitized solar cells (DSSC) and hybrid heterojunction solid-state solar cells. MAC-TiO2 layers can enhance light scattering as well as absorption, because their pore size and periodicity are comparable to light wavelength for unique multiple scattering and a porous surface can load dye more. Moreover, due to the bicontinuous nature of macropores and TiO2 walls, electrolyte could be transported much faster in between the TiO2 spheres rather than within the small TiO2 nonporous architectures. Electron transport was also facilitated along the interconnected TiO2 walls. In DSSCs with these MAC-TiO2 scattering layers, efficiency was higher than conventional DSSCs incorporating a commercial scattering layer. The unique geometry of MAC-TiO2 results in strong improvements in light scattering and infiltration of hole-transporting materials, thereby the MAC-TiO2-based solid-state device showed comparatively higher efficiency than the device with conventional nanocrystalline TiO2. PMID:24571409

Veerappan, Ganapathy; Jung, Dae-Woong; Kwon, Jeong; Choi, Jeong Mo; Heo, Nansra; Yi, Gi-Ra; Park, Jong Hyeok

2014-03-25

39

TiO2 Dye Sensitized Solar Cells Cathode Using Recycle Battery  

NASA Astrophysics Data System (ADS)

This paper proposed an alternative source of carbon material from recycled battery for the fabrication of cathode of a dye sensitized solar cell. Carbon from recycle battery is extracted and used to fabricate the cathode part of a dye sensitized solar cell by using TiO2 as the anode. The both anode and cathode is fabricated on a 6 × 2cm2 indium tin oxide (ITO) coated glass and then tested under the solar irradiance of 693.69 w/m2 and average temperature 44.4 oC. Result shows that by using carbon from a recycle battery a Voc of 0.333V and short circuit current of 166.04 ?A is produce.

Daut, I.; Fitra, M.; Irwanto, M.; Gomesh, N.; Irwan, Y. M.

2013-04-01

40

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

PubMed

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

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

2012-09-14

41

ZnO-Coated TiO2 Nanotube Arrays for a Photoelectrode in Dye-Sensitized Solar Cells  

NASA Astrophysics Data System (ADS)

In dye-sensitized solar cells, highly ordered TiO2 nanotube arrays as a photoelectrode have higher charge collection efficiencies than a nanoparticle-based structure due to their faster charge percolation and slower recombination of electrons. Highly ordered TiO2 nanotube arrays were grown by anodic oxidation of 0.5-mm-thick titanium foil. To increase the conversion efficiency of dye-sensitized solar cells with TiO2 nanotube arrays, the surface of the TiO2 nanotube arrays was modified by zinc oxide thin films. The ZnO thin film was formed by atomic layer deposition. The thin film was conformal on the inner and outer walls of TiO2 nanotube arrays. ZnO thin film improved the short circuit current ( J sc) and open circuit voltage ( V oc) due to increasing specific surface area from particulates of ZnO thin film and increasing the surface charge induced from the isoelectric point. The power conversion efficiency of dye-sensitized solar cells with ZnO thin film on 4.5- ?m-thick TiO2 nanotube arrays was 1.43%. Microstructure and phase were observed by scanning electron microscopy, x-ray diffractometry, and transmission electron microscopy.

Jeong, Jin-Su; Choe, Byung-Hak; Lee, Jung-Ho; Lee, Jae-Joon; Choi, Won-Youl

2014-02-01

42

In Situ Synthesis of Graphene Molecules on TiO2: Application in Sensitized Solar Cells.  

PubMed

We present a method for preparation of graphene molecules (GMs), whereby a polyphenylene precursor functionalized with surface anchoring groups, preadsorbed on surface of TiO2, is oxidatively dehydrogenated in situ via a Scholl reaction. The reaction, performed at ambient conditions, yields surface adsorbed GMs structurally and electronically equivalent to those synthesized in solution. The new synthetic approach reduces the challenges associated with the tendency of GMs to aggregate and provides a convenient path for integration of GMs into optoelectronic applications. The surface synthesized GMs can be effectively reduced or oxidized via an interfacial charge transfer and can also function as sensitizers for metal oxides in light harvesting applications. Sensitized solar cells (SSCs) prepared from mesoscopic TiO2/GM films and an iodide-based liquid electrolyte show photocurrents of ?2.5 mA/cm(2), an open circuit voltage of ?0.55 V and fill factor of ?0.65 under AM 1.5 illumination. The observed power conversion efficiency of ? = 0.87% is the highest reported efficiency for the GM sensitized solar cell. The performance of the devices was reproducible and stable for a period of at least 3 weeks. We also report first external and internal quantum efficiency measurements for GM SSCs, which point to possible paths for further performance improvements. PMID:25322280

Ji, Zhiqiang; Wu, Ruilian; Adamska, Lyudmyla; Velizhanin, Kirill A; Doorn, Stephen K; Sykora, Milan

2014-11-26

43

CdS quantum dot-sensitized solar cells based on nano-branched TiO2 arrays  

PubMed Central

Nano-branched rutile TiO2 nanorod arrays were grown on F:SnO2 conductive glass (FTO) by a facile, two-step wet chemical synthesis process at low temperature. The length of the nanobranches was tailored by controlling the growth time, after which CdS quantum dots were deposited on the nano-branched TiO2 arrays using the successive ionic layer adsorption and reaction method to make a photoanode for quantum dot-sensitized solar cells (QDSCs). The photovoltaic properties of the CdS-sensitized nano-branched TiO2 solar cells were studied systematically. A short-circuit current intensity of approximately 7 mA/cm2 and a light-to-electricity conversion efficiency of 0.95% were recorded for cells based on optimized nano-branched TiO2 arrays, indicating an increase of 138% compared to those based on unbranched TiO2 nanorod arrays. The improved performance is attributed to a markedly enlarged surface area provided by the nanobranches and better electron conductivity in the one-dimensional, well-aligned TiO2 nanorod trunks. PMID:24597830

2014-01-01

44

CdS quantum dot-sensitized solar cells based on nano-branched TiO2 arrays.  

PubMed

Nano-branched rutile TiO2 nanorod arrays were grown on F:SnO2 conductive glass (FTO) by a facile, two-step wet chemical synthesis process at low temperature. The length of the nanobranches was tailored by controlling the growth time, after which CdS quantum dots were deposited on the nano-branched TiO2 arrays using the successive ionic layer adsorption and reaction method to make a photoanode for quantum dot-sensitized solar cells (QDSCs). The photovoltaic properties of the CdS-sensitized nano-branched TiO2 solar cells were studied systematically. A short-circuit current intensity of approximately 7 mA/cm2 and a light-to-electricity conversion efficiency of 0.95% were recorded for cells based on optimized nano-branched TiO2 arrays, indicating an increase of 138% compared to those based on unbranched TiO2 nanorod arrays. The improved performance is attributed to a markedly enlarged surface area provided by the nanobranches and better electron conductivity in the one-dimensional, well-aligned TiO2 nanorod trunks. PMID:24597830

Liu, Chang; Li, Yitan; Wei, Lin; Wu, Cuncun; Chen, Yanxue; Mei, Liangmo; Jiao, Jun

2014-01-01

45

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

PubMed Central

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

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

2013-01-01

46

Hydrothermal synthesis of rutile-anatase TiO2 nanobranched arrays for efficient dye-sensitized solar cells  

NASA Astrophysics Data System (ADS)

Rutile-anatase TiO2 nanobranched arrays were prepared in two sequential hydrothermal-synthesis steps. The morphologies and crystalline nanostructures of the samples were investigated by controlling growth time and the concentration of the titanium precursor. All samples were characterized by field-emission scanning electron microscopy and X-ray diffraction analysis. It was found that treating the surfaces of rutile TiO2 nanorods with aqueous TiCl4 solutions allows the anatase TiO2 nanobranches to grow perpendicular to the main rutile TiO2 nanorods attached to the FTO glass. Irregularly shaped, dense TiO2 structures formed in the absence of TiCl4 treatment. A light-to-electricity conversion efficiency of 3.45% was achieved using 2.3 ?m tall TiO2 nanobranched arrays in a dye-sensitized solar cell. This value is significantly higher than that observed for pure rutile TiO2 nanorods.

Kwon, Soon Jin; Im, Hyo Been; Nam, Jung Eun; Kang, Jin Kyu; Hwang, Taek Sung; Yi, Kwang Bok

2014-11-01

47

TiO2 paste formulation for crack-free mesoporous nanocrystalline film of dye-sensitized solar cells.  

PubMed

Using a doctor-blade method, a highly viscous titanium dioxide (TiO2) paste was deposited on a glass substrate coated with fluorine doped tin oxide (FTO). The paste was mainly composed of commercially available TiO2 nanoparticles (P25) and hydroxypropyl cellulose (HPC) as organic filler. Varying the content of HPC in the TiO2 paste changed the physical properties of the mesoporous TiO2 layer, particularly its porosity and surface area. From the quantification of dyes on Ti2, layer and the electrochemical impedance spectroscopy (EIS) study of the dye-sensitized solar cells (DSSCs), the surface area of the TiO2 film was found to have decreased. This came with the increase of HPC content while the porosity of the film increased, consistent with the concurrent decrease of short-circuit current density (Jsc) and efficiency (eta). The increased porosity greatly affected the electron transport through the TiO2 film by decreasing the coordination number of the TiO2 particles resulting to a decrease of the electron diffusion coefficient. PMID:22966572

Sarker, Subrata; Nath, Narayan Chandra Deb; Rahman, M Mahbubur; Lim, Sung-Su; Ahammad, A J Saleh; Choi, Won-Youl; Lee, Jae-Joon

2012-07-01

48

An Integrated Power Pack of Dye-Sensitized Solar Cell and Li Battery Based on Double-Sided TiO2 Nanotube Arrays  

E-print Network

An Integrated Power Pack of Dye-Sensitized Solar Cell and Li Battery Based on Double-Sided TiO2 harvest and storage processes. This power pack incorporates a series-wound dye- sensitized solar cell material.11,15 Compared with other integrated solar power supplies,16,17 double-sided TiO2 NTs with large

Wang, Zhong L.

49

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

PubMed Central

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

2011-01-01

50

TiO2 nanotubes infiltrated with nanoparticles for dye sensitized solar cells  

NASA Astrophysics Data System (ADS)

We present a detailed study of the infiltration of titanium dioxide (TiO2) nanotubes (NTs) with TiO2 nanoparticles (NPs) for dye sensitized solar cells (DSSCs). The aim is to combine the merits of the NP's high dye loading and high light harvesting capability with the NT's straight carrier transport path and high electron collection efficiency to improve the DSSC performance. On infiltrating NTs with TiCl4 solution followed by hydrothermal synthesis, 10 nm size NPs were observed to form a conformal and dense layer on the NT walls. Compared with the bare NT structure, dye loading of this mixed NT and NP structure is more than doubled. The overall photon conversion efficiencies of the fabricated DSSCs are improved by 152%, 107%, and 49% for 8, 13, and 20 µm long NTs, respectively. Electron transport and recombination parameters were extracted based on electrochemical impedance spectroscopy measurements. Although a slight reduction of electron lifetime was observed in the mixed structures due to enhanced recombination with a larger surface area, the diffusion length is still significantly longer than the NT length used, suggesting that most electrons are collected. In addition to dye loading and hence photocurrent increment, the photovoltage and filling factor were also improved in the mixed structure due to a low serial resistance, leading to the enhancement of the overall efficiency.

Pan, Xuan; Chen, Changhong; Zhu, Kai; Fan, Zhaoyang

2011-06-01

51

DFT-MD approach to TiO2/liquid interface systems for photocatalysis and dye-sensitised solar cell  

E-print Network

DFT-MD approach to TiO2/liquid interface systems for photocatalysis and dye-sensitised solar cell cell (DSC) on the atomic and electronic scales for the last few years. Our final goal is understanding the equilibrium structures and electronic states at the solid- liquid interfaces Figure 1: Typical reaction

Katsumoto, Shingo

52

TiO2 nanotubes/nanoparticles composite film with higher light harvesting and electron transfer for dye-sensitized solar cells  

NASA Astrophysics Data System (ADS)

TiO2 nanotubes with an inner diameter of 4-6 nm were synthesized by hydrothermal treatment method. TiO2 nanotubes/nanoparticles composite films were fabricated as a dye-sensitized solar cells work electrode using TiO2 nanotubes and TiO2 nanoparticles as precursor. The structure of composite films has a remarkable influence on the final performance of the cell due to high surface area, fast electron transfer, enhanced light-scattering and light-harvesting, simultaneously. I-V characteristic measurement indicates an enhanced efficiency by 27% as compared to TiO2 nanotubes film.

Liu, Chengcheng; Liu, Zhifeng; E, Lei; Li, Yabin; Han, Jianhua; Wang, Yun; Liu, Zhichao; Ya, Jing; Chen, Xuhuang

2012-10-01

53

Effect of Surface Protonation on Device Performance and Dye Stability of Dye-sensitized TiO2 Solar Cell  

NASA Astrophysics Data System (ADS)

A flat thin TiO2 film was employed as the photo-electrode of a dye sensitized solar cell (DSSC), on which only a geometrical mono-layer of dye was attached. The effect of surface protonation by HCl chemical treatment on the performance of DSSCs was studied. The results showed that the short-circuit current Jsc increased significantly upon the HCl treatment, while the open-circuit voltage Voc decreased slightly. Compared to the untreated DSSC, the Jsc and energy conversion efficiency was increased by 31% and 25%, respectively, for the 1 mol/L HCl treated cell. TiO2 surface protonation improved electronic coupling between the chemisorbed dye and the TiO2 surface, resulting in an enhanced electron injection. The decreased open-circuit voltage after TiO2 surface protonation was mainly due to the TiO2 conduction band edge downshift and was partially caused by increased electron recombination with the electrolyte. In situ Raman degradation study showed that the dye stability was improved after the TiO2 surface protonation. The increased dye stability was contributed by the increased electron injection and electron back reaction with the electrolyte under the open-circuit condition.

Wu, Kun-jie; Shen, Kai; Yu, Yang; Wang, De-liang

2012-12-01

54

Growth of seaweed-like TiO2 nanoarrays for dye-sensitized solar cells  

NASA Astrophysics Data System (ADS)

Seaweed-like titanium dioxide (TiO2) nanoarrays (STNAs) were grown on the surface of a titanium (Ti) sheet by hydrogen peroxide sculpture at low temperature. After calcination, the STNA transformed to highly crystalline anatase phase and exhibited a vertically standing structure, with an average length of 1.35-2.12 ?m, leaves breadth of about 30-80 nm, and leaves thickness of about 10-15 nm. STNA-electrode dye-sensitized solar cells (DSCs) fabricated with dye C106 achieved an efficiency of 3.2% under irradiation of 100 mWcm?2 air mass 1.5 global (AM1.5G) sunlight. Further research showed that the STNA-electrode DSC has much lower recombination rate (Kr) and longer electron life time (?n), thus making this STNA a potential candidate of electrode for fabricating high performance DSC.

Bala, Hari; Jiang, Lei; Fu, Wuyou; Yuan, Guangyu; Wang, Xiaodong; Liu, Zongrui

2010-10-01

55

Oriented ZnO nanotubes arrays decorated with TiO2 nanoparticles for dye-sensitized solar cell applications  

NASA Astrophysics Data System (ADS)

Dye-sensitized solar cells (DSSCs) based on a novel composite photoanode of TiO2 nanoparticles coating on electrodeposited ZnO nanotube arrays are fabricated and characterized. An efficiency of 3.94 % is achieved for the composite cell, increasing 86.7 % than 2.11 % of the ZnO nanotubes cell. The short-circuit current ( J sc) and open-circuit voltage ( V oc) are also enhancing 52.9 % and 25.3 %, respectively. The improvements are because of the high surface area of TiO2 nanoparticles, as well as fast electron transport and light scattering effect of ZnO nanotubes.

Yang, Jiyuan; Lin, Yu; Meng, Yongming; Lin, Yibing

2014-03-01

56

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

NASA Astrophysics Data System (ADS)

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.

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

2012-02-01

57

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

PubMed

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. PMID:22297128

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

2012-01-01

58

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

PubMed Central

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. PMID:22297128

2012-01-01

59

Electrospun hierarchical TiO2 nanorods with high porosity for efficient dye-sensitized solar cells.  

PubMed

Ultraporous anatase TiO2 nanorods with a composite structure of mesopores and macropores fabricated via a simple microemulsion electrospinning approach were first used as photoanode materials for high-efficiency dye-sensitized solar cells (DSSCs). The special multiscale porous structure was formed by using low-cost paraffin oil microemulsion droplets as the soft template, which can not only provide enhanced adsorption sites for dye molecules but also facilitate the electrolyte diffusion. The morphology, porosity, and photovoltaic and electron dynamic characteristics of the porous TiO2 nanorod based DSSCs were investigated in detail by scanning electron microscopy (SEM), N2 sorption measurements, current density-voltage (J-V) curves, UV-vis diffuse reflectance spectra, electrochemical impedance spectroscopy (EIS), intensity modulated photocurrent/photovoltage spectroscopy (IMPS/IMVS), and open-circuit voltage decay (OCVD) measurements. The results revealed that, although fewer amounts of dyes were anchored on the porous TiO2 nanorod films, they exhibited stronger light scattering ability, fast electrolyte diffusion, and extended electron lifetime compared to the commercial P25 nanoparticles. A power conversion efficiency of 6.07% was obtained for the porous TiO2 nanorod based DSSCs. Moreover, this value can be further improved to 8.53% when bilayer structured photoanode with porous TiO2 nanorods acting as the light scattering layer was constructed. This study demonstrated that the porous TiO2 nanorods can work as promising photoanode materials for DSSCs. PMID:23962052

Chen, Hong-Yan; Zhang, Teng-Long; Fan, Jie; Kuang, Dai-Bin; Su, Cheng-Yong

2013-09-25

60

Designed architecture of multiscale porous TiO2 nanofibers for dye-sensitized solar cells photoanode.  

PubMed

Multiscale porous (MSP) TiO(2) nanofibers (NFs) were fabricated using a simple electrospinning and etching process with TiO(2)/SiO(2) composite NFs for high-efficiency dye-sensitized solar cells (DSSCs). TiO(2) NFs with different pore sizes (small, large, and multiscale) were prepared using SiO(2) nanoparticles of various sizes. The surface area of the MSP TiO(2) NFs was nine times higher than that of pristine TiO(2) NFs, providing sufficient dye adsorption for light harvesting as well as efficient paths for electrolyte contact. Moreover, the one-dimensional structure provides efficient light scattering and fast electron transport. As a result, DSSCs exhibited an enhanced current density (J(sc)) of 16.3 mA cm(-2) and a high photoconversion efficiency (?) of 8.5%, greater than those of conventional photoelectrodes made of TiO(2) nanoparticles (J(sc) of 12.0 mA cm(-2) and ? of 6.0 %). PMID:22985179

Hwang, Sun Hye; Kim, Chanhoi; Song, Hee; Son, Suim; Jang, Jyongsik

2012-10-24

61

Multi-core cable-like TiO2 nanofibrous membranes for dye-sensitized solar cells  

NASA Astrophysics Data System (ADS)

Multi-core cable-like TiO2 nanofibres were fabricated by calcination of composite polyvinyl acetate (PVAc)/titania nanofibres with a hot pressing pre-treatment. This resultant novel fibre structure was composed of sheaths of 200 nm in diameter and 25 nm in wall thickness, and cores filled with 24 nm thick TiO2 fibrils. The formation of multi-core cable-like structures of fibres is considered to be due to the enhanced phase separation of PVAc-rich and TiO2-rich phases during the hot pressing process. The BET results showed that the specific surface area of pressed TiO2 membranes was much higher than that of unpressed TiO2 membranes. In this study, the novel multi-core cable-like TiO2 fibrous membranes were used as electrode materials for dye-sensitized solar cells (DSSCs). It was observed that the photocurrent and conversion efficiency of the electrodes increased concurrently with increasing applied pressure and average membrane thickness in the range of 1-9 µm. The maximum short circuit photocurrent and energy conversion efficiency were 16.09 mA cm-2 and 5.77% when the membrane had an average thickness of 9.21 µm and 8 MPa applied pressure.

Kokubo, Hiroshi; Ding, Bin; Naka, Takayuki; Tsuchihira, Hiroki; Shiratori, Seimei

2007-04-01

62

Influence of TiO2 coating thickness on energy conversion efficiency of dye-sensitized solar cells  

NASA Astrophysics Data System (ADS)

Dye-sensitized solar cells (DSSCs) were synthesized using a 0.25 cm2 area TiO2 nanoparticle/nanorod layer as an electrode and platinum (Pt) as a counter electrode. The TiO2 nanoparticle/nanorod layer was prepared by spin coating and spray coating on fluorine-doped tin oxide glass, respectively. The Pt counter electrode and the ruthenium dye anchored electrode were then assembled as a function of thickness of the TiO2 nanorod layer in a range of 8 to 30 µm. The best photovoltaic performance was observed in the case of a DSSC consisting of a 600 nm thick TiO2 nanoparticle layer and a 20 µm thick TiO2 nanorod layer: a short circuit current density of 11.54 mA·cm-2, open circuit voltage of 0.72V, fill factor of 61.2%, and energy conversion efficiency of 5.07%. A TiO2 nanorod/nanoparticle electrode layer with good adhesion was successfully fabricated.

Kim, Young-Hun; Lee, In-Kyu; Song, Yo-Seung; Lee, Myung-Hyun; Kim, Bae-Yeon; Cho, Nam-Ihn; Lee, Deuk Yong

2014-03-01

63

Fabrication of a multi-scale nanostructure of TiO2 for application in dye-sensitized solar cells  

NASA Astrophysics Data System (ADS)

We propose a highly ordered multi-scale nanostructure of TiO2 for applications as an anode in dye-sensitized solar cells (DSSCs). The structure is composed of a TiO2 blocking layer, a TiO2 inverse opal main body, regularly arranged transport channels between contacting spherical voids of the TiO2 inverse opal, and TiO2 nanoparticles coated on the spherical surfaces of the voids. The ordered and continuous backbone of the inverse opal serves as the fast electron transport pathways while the regularly arranged transport channels enable easy transport of dye and electrolyte within the structure. A multi-cycle procedure was developed to enable fabrication of thick inverse opals and easy adjustment of the inverse opal thickness. An example structure was constructed, involving a blocking layer of 90 nm thickness, an inverse opal of 100 nm voids, transport channels of 30-50 nm openings, and nanoparticles 10-15 nm in size. An open-circuit voltage decay investigation showed a significant improvement in electron lifetime for the proposed multi-scale TiO2 nanostructure based DSSC than that of a TiO2 nanoparticle film based DSSC, revealing the superior electron recombination characteristic offered by the proposed TiO2 nanostructure. The conversion efficiency of the DSSC assembled from such an anode structure can reach 4% with a short-circuit current density (Jsc) of 8.7 mA cm-2 and open-circuit potential (Voc) of 0.76 V under AM 1.5 (100 mW cm-2) illumination.

Kuo, Cheng-Yu; Lu, Shih-Yuan

2008-03-01

64

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

PubMed

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. PMID:25007378

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

2014-08-28

65

Electrochemical impedance spectroscopy of dye-sensitized solar cells with thermally degraded N719 loaded TiO2  

NASA Astrophysics Data System (ADS)

Here, we have deliberately degraded N719 loaded TiO2 photoelectrodes (PEs) at elevated temperatures; for example, from 80 °C to 160 °C with a step of 40 °C and studied their influence on photovoltaic parameters of dye-sensitized solar cells (DSSCs). Electrochemical impedance spectroscopy (EIS) study shows that the thermal degraded PEs suffered from increased recombination as well as downward shift of TiO2 conduction band that eventually decreased photovoltage of the cells. In contrast, incident photon-to-current efficiency (IPCE) reveals that poor light harvesting, charge collection and dye regeneration efficiency were responsible for low photocurrent of the DSSCs with thermal degraded PEs.

Sarker, Subrata; Seo, Hyun Woo; Kim, Dong Min

2013-10-01

66

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

PubMed Central

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

2012-01-01

67

High efficiency dye-sensitized solar cell based on novel TiO2 nanorod/nanoparticle bilayer electrode  

PubMed Central

High light-to-energy conversion efficiency was achieved by applying novel TiO2 nanorod/nanoparticle (NR/NP) bilayer electrode in the N719 dye-sensitized solar cells. The short-circuit current density (JSC), the open-circuit voltage (VOC), the fill factor (FF), and the overall efficiency (?) were 14.45 mA/cm2, 0.756 V, 0.65, and 7.1%, respectively. The single-crystalline TiO2 NRs with length 200–500 nm and diameter 30–50 nm were prepared by simple hydrothermal methods. The dye-sensitized solar cells with pure TiO2 NR and pure TiO2 NP electrodes showed only a lower light-to-electricity conversion efficiency of 4.4% and 5.8%, respectively, compared with single-crystalline TiO2 NRs. This can be attributed to the new NR/NP bilayer design that can possess the advantages of both building blocks, ie, the high surface area of NP aggregates and rapid electron transport rate and the light scattering effect of single-crystalline NRs. PMID:24198470

Hafez, Hoda; Lan, Zhang; Li, Qinghua; Wu, Jihuai

2010-01-01

68

Microwave assisted CdSe quantum dot deposition on TiO2 films for dye-sensitized solar cells.  

PubMed

CdSe quantum dot (QD ) sensitized TiO(2) films have been fabricated using a one-step microwave assisted chemical bath deposition (MACBD) technique and used as photoanodes for quantum dot sensitized solar cells. This technique allows direct and rapid deposition and a good contact between the CdSe and TiO(2) films. The photovoltaic performances of the cells with CdSe deposited at different times are investigated. The results show that cells based on MACBD deposited TiO(2)/CdSe electrodes achieve a maximum short circuit current density of 12.1 mA cm(-2) and a power conversion efficiency of 1.75% at one Sun (AM 1.5 G, 100 mW cm(-2)), which is comparable with those fabricated using conventional techniques. PMID:21451826

Zhu, Guang; Pan, Likun; Xu, Tao; Zhao, Qingfei; Lu, Bin; Sun, Zhuo

2011-05-01

69

A study of TiO2/carbon black composition as counter electrode materials for dye-sensitized solar cells  

PubMed Central

This study describes a systematic approach of TiO2/carbon black nanoparticles with respect to the loading amount in order to optimize the catalytic ability of triiodide reduction for dye-sensitized solar cells. In particular, the cell using an optimized TiO2 and carbon black electrode presents an energy conversion efficiency of 7.4% with a 5:1 ratio of a 40-nm TiO2 to carbon black. Based on the electrochemical analysis, the charge-transfer resistance of the carbon counter electrode changed based on the carbon black powder content. Electrochemical impedance spectroscopy and cyclic voltammetry study show lower resistance compared to the Pt counter electrode. The obtained nanostructures and photo electrochemical study were characterized. PMID:23672498

2013-01-01

70

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

NASA Astrophysics Data System (ADS)

Quantum dot-sensitized solar cells based on Zn-doped TiO2 (Zn-TiO2) film photoanode and polysulfide electrolyte were fabricated. Zn-TiO2 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-TiO2/CdS film and the photovoltaic performance of the Zn-TiO2/CdS cell were investigated. It was found that the photovoltaic efficiency was improved by 24% when the Zn-TiO2 film was adopted as the photoanode of CdS QDSSCs instead of only the TiO2 layer. The improvement was ascribed to the reduction of electron recombination and the enhancement of electron transport in the TiO2 film by Zn doping.

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

2010-07-01

71

A study of TiO2/carbon black composition as counter electrode materials for dye-sensitized solar cells  

NASA Astrophysics Data System (ADS)

This study describes a systematic approach of TiO2/carbon black nanoparticles with respect to the loading amount in order to optimize the catalytic ability of triiodide reduction for dye-sensitized solar cells. In particular, the cell using an optimized TiO2 and carbon black electrode presents an energy conversion efficiency of 7.4% with a 5:1 ratio of a 40-nm TiO2 to carbon black. Based on the electrochemical analysis, the charge-transfer resistance of the carbon counter electrode changed based on the carbon black powder content. Electrochemical impedance spectroscopy and cyclic voltammetry study show lower resistance compared to the Pt counter electrode. The obtained nanostructures and photo electrochemical study were characterized.

Lim, Jeongmin; Ryu, Sang Yeoul; Kim, Jeonghun; Jun, Yongseok

2013-05-01

72

Front-illuminated dye-sensitized solar cells with Ag nanoparticle-functionalized freestanding TiO2 nanotube arrays  

NASA Astrophysics Data System (ADS)

Dye-sensitized solar cells (DSSCs) were fabricated with Ag nanoparticle (NP)-embedded TiO2 nanotube arrays by using UV irradiation. The energy conversion efficiency was increased from 4.64% to 6.14% by the Ag functionalization, a 32% enhancement, which is attributed to surface plasmon resonances present along the entire length of the TiO2 nanotube arrays. Furthermore, the Ag NPs more effectively enhanced the energy conversion efficiencies in front-illuminated DSSCs than in back-illuminated ones.

Rho, Won-Yeop; Kim, Ho-Sub; Lee, Sang Hun; Jung, Seunho; Suh, Jung Sang; Hahn, Yoon-Bong; Jun, Bong-Hyun

2014-10-01

73

Structural and optical properties of silver doped TiO2 thin films for solar cell applications  

NASA Astrophysics Data System (ADS)

Electron collection efficiency and hence the device performance of a dye sensitized solar cell can be increased by localized surface plasmons (LSP) produced by the thin films of 2% silver doped TiO2 photo electrode. These films of silver doped TiO2 on glass substrates are prepared by pulsed laser deposition (PLD) method and have a lowest grain size of 8-31 nm. XRD, AFM and raman studies are made to characterize the surface at various annealing temperatures and annealing time durations. The lowest grain size of 8 nm of these films developed.

Murty, V. V. S.; Dashore, Vinay

2014-09-01

74

Effect of Co-sensitization and acid treatment on TiO2 photoanodes in dye-sensitized solar cells  

NASA Astrophysics Data System (ADS)

The performance of dye-sensitized solar cells is improved by simple formic acid treatment of TiO2 photoanodes. The treatment increases number of hydroxyl groups at TiO2 surface and thereby result in enhanced dye-loading and device efficiency. The best device showed an open circuit voltage of 0.62V, short-circuit current density 6.34mA/cm2, fill factor of 60%, and a power conversion efficiency of ˜12 % under 20mW/cm2 white light illumination.

Veerender, P.; Saxena, Vibha; Gusain, Abhay; Jha, P.; Koiry, S. P.; Chauhan, A. K.; Aswal, D. K.; Gupta, S. K.

2013-02-01

75

Fabrication of dye-sensitized solar cells using TiO 2-nanotube arrays on Ti-grid substrates  

Microsoft Academic Search

Self-aligned TiO2 nanotube arrays (20 ?m in length) were fabricated by anodic oxidation of Ti-grid with a thickness of 100 ?m in an ethylene glycol electrolyte with an addition of H2O (1.5 vol.%) and NH4F (0.2 wt.%). Voltage applied between Ti and Pt cathodes is 60 V at ~22 °C. Dye-sensitized solar cell utilizing photoanode structure of TiO2-nanotube\\/Ti-grid was fabricated with no transparent conducting oxide (TCO)

K. Y. Chun; B. W. Park; Y. M. Sung; D. J. Kwak; Y. T. Hyun; M. W. Park

2009-01-01

76

One Step Preparation of TiO2 Layer for High Efficiency Dye-sensitized Solar Cell.  

PubMed

A novel titanium dioxide paste based on Pechini sol-gel method and nanocrystalline TiO2 powder has been successfully developed and tested. The paste enables the formation of sponge like structure of the TiO2 layer i.e. highly porous and at the same time well connected TiO2 network. The layers have been used to assemble dye sensitized solar cells (DSSC) with two ruthenium complex based dyes, N719 and black dye, respectively. Overall conversion efficiencies of ionic liquid electrolyte based DSSC sensitized with N719 and black dye was 6.1% and 2.0%, respectively, when determined under standard test conditions (100 mW/cm2, AM1.5, 25 °C). PMID:24061737

Ho?evar, Opara; Berginc, Marko; Topi?, Marko

2010-06-01

77

Semiconductor Quantum Dot-Sensitized Solar Cells Employing TiO2 Nanostructured Photoanodes with Different Morphologies  

NASA Astrophysics Data System (ADS)

CdSe quantum dot (QD)-sensitized solar cells (QDSCs) were synthesized by adsorbing CdSe QDs onto TiO2 nanostructured electrodes with different morphologies, i.e., nanoparticles, nanotubes, and inverse opals. The optical absorption, photoelectrochemical, and photovoltaic properties of the QDSCs were characterized and the dependences of these properties on the QD deposition time and the TiO2 nanostructure are discussed. To improve the photovoltaic performance of the CdSe QDSCs, surface passivation with a ZnS coating was introduced and Cu2S counter electrodes were applied. All aspects of the photovoltaic performance, including the short-circuit photocurrent density, open-circuit voltage, fill factor, and efficiency, were found to be significantly improved by the surface modification with ZnS. For the counter electrode, the Cu2S electrode was demonstrated to be more efficient than platinum against the polysulfide electrolytes usually used as redox couples in CdSe QDSCs. Moreover, CdS QD adsorption on the TiO2 electrodes prior to CdSe QD adsorption also resulted in better solar cell performance. In addition, we found that the morphology of the TiO2 electrodes had a great influence on the photovoltaic properties of the QDSCs. Finally, a power conversion efficiency as high as 4.9% was achieved for a combined CdS/CdSe QDSC under solar illumination of 100 mW/cm2.

Shen, Qing; Toyoda, Taro

78

Conversion efficiency versus sensitizer for electrospun TiO2 nanorod electrodes in dye-sensitized solar cells  

NASA Astrophysics Data System (ADS)

The electrochemical and optical properties of three indoline dyes, namely C35H28N2O2 (D131), C37H30N2O3S2 (D102), and C42H35N3O4S3 (D149), were studied and compared with that of the N3 dye. D131 has the largest bandgap and lowest unoccupied molecular orbital (LUMO) energies compared to the other dyes. A size-dependent variation in the absorptivity of the indoline dyes was observed—the absorptivity increased with increase in the molecular size. The dyes were anchored onto TiO2 nanorods. The TiO2 nanorods were obtained by electrospinning a polymeric solution containing titanium isopropoxide and polyvinylpyrrolidone and subsequent sintering of the as-spun composite fibers. Absorption spectral measurements of the dye-anchored TiO2 showed blue shifts in the excitonic transition of the indoline dyes, the magnitude of which increased with decrease in the molecular size. Dye-sensitized solar cells (DSSCs) were fabricated using the indoline dyes, TiO2 nanorods, and iodide/triiodide electrolyte. The D131 dye showed comparable energy conversion efficiency (?) to that of the N3 dye. A systematic change in the short circuit current density (JSC) and ? of the indoline DSSCs was observed. The observed variation in JC is most likely originated from the difference in the electronic coupling strengths between the dye and the TiO2.

Jose, R.; Kumar, A.; Thavasi, V.; Ramakrishna, S.

2008-10-01

79

TiO 2 thin films as protective material for transparent-conducting oxides used in Si thin film solar cells  

Microsoft Academic Search

Nb-doped TiO2 films have been fabricated by RF magnetron sputtering as protective material for transparent-conducting oxide (TCO) films used in Si thin film solar cells. It is found that TiO2 has higher resistance against hydrogen radical exposure, utilizing the hot-wire CVD (catalytic CVD) apparatus, compared with SnO2 and ZnO. Further, the minimum thickness of TiO2 film as protective material for

H. Natsuhara; K. Matsumoto; N. Yoshida; T. Itoh; S. Nonomura; M. Fukawa; K. Sato

2006-01-01

80

Effect of TiO2 nanotubes with TiCl4 treatment on the photoelectrode of dye-sensitized solar cells  

PubMed Central

In this study, we used the electrochemical anodization to prepare TiO2 nanotube arrays and applied them on the photoelectrode of dye-sensitized solar cells. In the field emission scanning electron microscopy analysis, the lengths of TiO2 nanotube arrays prepared by electrochemical anodization can be obtained with approximately 10 to 30 ?m. After titanium tetrachloride (TiCl4) treatment, the walls of TiO2 nanotubes were coated with TiO2 nanoparticles. XRD patterns showed that the oxygen-annealed TiO2 nanotubes have a better anatase phase. The conversion efficiency with different lengths of TiO2 nanotube photoelectrodes is 3.21%, 4.35%, and 4.34% with 10, 20, and 30 ?m, respectively. After TiCl4 treatment, the efficiency of TiO2 nanotube photoelectrode for dye-sensitized solar cell can be improved up to 6.58%. In the analysis of electrochemical impedance spectroscopy, the value of Rk (charge transfer resistance related to recombination of electrons) decreases from 26.1 to 17.4 ? when TiO2 nanotubes were treated with TiCl4. These results indicate that TiO2 nanotubes treated with TiCl4 can increase the surface area of TiO2 nanotubes, resulting in the increase of dye adsorption and have great help for the increase of the conversion efficiency of DSSCs. PMID:23092158

2012-01-01

81

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)

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%).

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

2014-01-01

82

Slow interfacial charge recombination in solid-state dye-sensitized solar cell using Al 2O 3-coated nanoporous TiO 2 films  

Microsoft Academic Search

Al2O3-coated TiO2 porous films were used to fabricate solid-state dye-sensitized solar cells using CuI as hole conductor. Investigation with transient photovoltage measurements showed that the Al2O3 interlayer slowed down the interfacial recombination of electrons in TiO2 with holes in CuI by forming a potential barrier at the TiO2\\/CuI interface. As a consequence, the cell made from Al2O3-coated TiO2 film showed

Xin-Tong Zhang; Hong-Wu Liu; Taketo Taguchi; Qing-Bo Meng; Osamu Sato; Akira Fujishima

2004-01-01

83

Solid-state dye-sensitized solar cells fabricated with nanoporous TiO 2 and TPD dyes: Analysis of penetration behavior and I-V characteristics  

NASA Astrophysics Data System (ADS)

We present the synthesis, electrochemical properties and device-based investigation of triphenylene diamine (TPD) sensitizer with an extended ? system consisting of donor, electron conducting and anchoring group for solid-state dye-sensitized solar cells. Solid-state dye-sensitized solar cells were fabricated using blocking TiO2 electrodes, nanoporous TiO2 electrodes and the organic hole-transporting medium, HTM (spiro-OMeTAD) in a fluorine doped tin oxide/blocking TiO2/nanoporous TiO2/TPDs/hole transport material/Au configuration. Solid state dye sensitized solar cell consisting of TPD_2 as sensitizer on mesoporous TiO2 shows the best results with a short-circuit current of 2.8 mA/cm2, an open circuit voltage of 835 mV and an overall conversion efficiency of 0.97%.

Erten-Ela, Sule; Brendel, Johannes; Thelakkat, Mukundan

2011-06-01

84

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

PubMed Central

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

2013-01-01

85

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

NASA Astrophysics Data System (ADS)

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.

Jung, Young Hee; Park, Kyung-Hee; Oh, Jeong Seok; Kim, Do-Heyoung; Hong, Chang Kook

2013-01-01

86

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

PubMed

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

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

2013-11-01

87

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

NASA Astrophysics Data System (ADS)

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.

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

2013-11-01

88

Incorporating carbon nanotube in a low-temperature fabrication process for dye-sensitized TiO 2 solar cells  

Microsoft Academic Search

Dye-sensitized solar cells (DSSCs) incorporating TiO2 porous films, prepared at a low temperature (150°C), along with multi-wall carbon nanotubes (MWCNTs) were studied using two different electrolytes, namely LiI and THI. Electrochemical impedance spectroscopy (EIS) was employed to quantify the charge transport resistance and electron lifetime (?e) under different levels (wt%) of MWCNTs and electrolytes. The charge transport resistance at the

Kun-Mu Lee; Chih-Wei Hu; Hsin-Wei Chen; Kuo-Chuan Ho

2008-01-01

89

Investigation of sputter-deposited TiO 2 thin film for the fabrication of dye-sensitized solar cells  

Microsoft Academic Search

Nanocrystalline TiO2 films were prepared by facing target reactive sputtering on SnO2:F coated glass substrates with different sputtering pressures: 1.2 Pa, 1.6 Pa and 2.0 Pa for the fabrication of dye-sensitized solar cells (DSCs). These films were sensitized with a dye solution of chlorophyllin–sodium copper salt in water. The amount of dye incorporation was found to be highly dependent on the microstructure of

M. F. Hossain; S. Biswas; T. Takahashi; Y. Kubota; A. Fujishima

2008-01-01

90

The performance of coupled (CdS:CdSe) quantum dot-sensitized TiO 2 nanofibrous solar cells  

Microsoft Academic Search

Highly porous networks and reduced grain boundaries with one-dimensional (1-D) nanofibrous morphology offer enhanced charge transport in solar cells applications. Quantum dot (QDs) decorated TiO2 nanofibrous electrodes, unlike organic dye sensitizers, can yield multiple carrier generations due to the quantum confinement effect. This paper describes the first attempt to combine these two novel approaches, in which CdS (?18nm) and CdSe

P. Sudhagar; June Hyuk Jung; Yong-Gun Lee; R. Sathyamoorthy; Yong Soo Kang; Heejoon Ahn

2009-01-01

91

Improvement on the Electron Transfer of Dye-Sensitized Solar Cell Using Vanadium Doped TiO2  

NASA Astrophysics Data System (ADS)

In dye-sensitized solar cells, nanoporous structure of TiO2 is very important for efficient cell because lots of dye molecules are adsorbable and they are the source of the photocurrent. However, the internal impedance of TiO2 is relatively large and it limits the performance. For better performance, vanadium was doped into TiO2 in this work. Doping different material generally improves the characteristics and functions of original materials. Vanadium doping has some advantages such as the reduction of internal resistance, the improvement of chemical stability and high absorption. Especially, reduced internal resistance is so helpful for better electron transfer in TiO2 network. Various amounts of vanadium were applied and photovoltaic performance, internal impedance and absorbance were measured in order to verify the effect of vanadium doping. As a result, vanadium doping improved the overall performance from 6.01 to 6.81% with decreased internal resistance although adsorbed dye amount was reduced by decreased surface area and open circuit voltage was also decreased by the change of band-gap energy.

Seo, Hyunwoong; Wang, Yuting; Ichida, Daiki; Uchida, Giichiro; Itagaki, Naho; Koga, Kazunori; Shiratani, Masaharu; Nam, Sang-Hun; Boo, Jin-Hyo

2013-11-01

92

Designed synthesis and stacking architecture of solid and mesoporous TiO(2) nanoparticles for enhancing the light-harvesting efficiency of dye-sensitized solar cells.  

PubMed

We fabricated solid and mesoporous TiO2 nanoparticles (NPs) with relatively large primary sizes of approximately 200 nm via inorganic templates for aero-sol-gel and subsequent aqueous-washing processes. The amount of dye molecules adsorbed by the internal pores in the mesoporous TiO2 NPs was increased by creating the nanopores within the solid TiO2 NPs. Simultaneously, the light-scattering effect of the mesoporous TiO2 NPs fabricated by this approach was secured by maintaining their spherical shape and relatively large average size. By precisely accumulating the fabricated solid or mesoporous 200 nm diameter TiO2 NPs on top of a conventional 25 nm diameter TiO2 NP-based underlayer, we could systematically examine the effect of the solid and mesoporous TiO2 NPs on the photovoltaic performance of dye-sensitized solar cells (DSSCs). Consequently, the stacking architecture of the mesoporous TiO2 NP-based overlayer, which functioned as both a light-scattering and dye-supporting medium, on top of a conventional solid TiO2 NP-based underlayer in a DSSC photoelectrode (i.e., double-layer structures) was found to be very promising for significantly improving the photovoltaic properties of conventional solid TiO2 NP single-layer-based DSSCs. PMID:24377279

Ahn, Ji Young; Moon, Kook Joo; Kim, Ji Hoon; Lee, Sang Hyun; Kang, Jae Wook; Lee, Hyung Woo; Kim, Soo Hyung

2014-01-22

93

Morphological studies of vertical arrays TiO2 nanotubes by electrochemical anodization technique for dye sensitized solar cell application  

NASA Astrophysics Data System (ADS)

A vertical array titanium dioxide nanotube (n-TiO2) for photovoltaic materials in dye sensitized solar cell has been synthesized by electrochemical anodization technique in NH4F aqueous solution. The morphological observation performed by SEM analysis on the scratch film showed that the distribution growths of TiO2 nanotubes on Ti subtract were uniform. The duration of growth is varied up to 12 h, with tubes length approximately 1 ?m. However, at the maximum duration, a compact TiO2 layers were formed. This phenomenon is due to the field-assisted anodic oxidation at the interfaces of Ti/TiO2 is at equal rate with the field-assisted dissolution rate of the top TiO2 nanotube's surface, resulting from the decreased quantity of F- ions to form fluoro complexes, [TiF6]2-. A slight increase in the rate of the chemical dissolution reaction produced a precipitated TiO2. Hence, [TiF6]2- complexes which are required for tubes formation are difficult to exist.

Su'ait, M. S.; Alamgir, F.; Scardi, P.; Ahmad, A.

2013-11-01

94

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

NASA Astrophysics Data System (ADS)

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 ?m). 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 ?m). 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.

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

2014-05-01

95

Oligothiophene Interlayer Effect on Photocurrent Generation for Hybrid TiO2/P3HT Solar Cells.  

PubMed

A series of conjugated 3-hexylthiophene derivatives with a cyanoacrylic acid group has been prepared with conjugation length from one up to five thiophene units (1T-5T). The UV-vis spectra, photoluminescence spectra, electrochemical data and DFT calculations show lowering of LUMO energies and red-shift of absorption into the visible as the thiophene chain length increases. TiO2/P3HT solar cells were prepared with prior functionalization of the TiO2 surface by 1T-5T and studies include cells using undoped P3HT and using P3HT doped with H-TFSI. Without H-TFSI doping, photocurrent generation occurs from both the oligothiophene and P3HT. Doping the P3HT with H-TFSI quenches photocurrent generation from excitation of P3HT, but enables very effective charge extraction upon excitation of the oligothiophene. In this case, photocurrent generation increases with the light harvesting ability of 1T-5T leading to a highest efficiency of 2.32% using 5T. Overall, we have shown that P3HT can act in either charge generation or in charge collection, but does not effectively perform both functions simultaneously, and this illustrates a central challenge in the further development of TiO2/P3HT solar cells. PMID:25233009

Planells, Miquel; Abate, Antonio; Snaith, Henry J; Robertson, Neil

2014-10-01

96

Dye-sensitized solar cells with vertically aligned TiO2 nanowire arrays grown on carbon fibers.  

PubMed

One-dimensional semiconductor TiO2 nanowires (TNWs) have received widespread attention from solar cell and related optoelectronics scientists. The controllable synthesis of ordered TNW arrays on arbitrary substrates would benefit both fundamental research and practical applications. Herein, vertically aligned TNW arrays in situ grown on carbon fiber (CF) substrates through a facile, controllable, and seed-assisted thermal process is presented. Also, hierarchical TiO2 -nanoparticle/TNW arrays were prepared that favor both the dye loading and depressed charge recombination of the CF/TNW photoanode. An impressive conversion efficiency of 2.48 % (under air mass 1.5 global illumination) and an apparent efficiency of 4.18 % (with a diffuse board) due to the 3D light harvesting of the wire solar cell were achieved. Moreover, efficient and inexpensive wire solar cells made from all-CF electrodes and completely flexible CF-based wire solar cells were demonstrated, taking into account actual application requirements. This work may provide an intriguing avenue for the pursuit of lightweight, cost-effective, and high-performance flexible/wearable solar cells. PMID:24488679

Cai, Xin; Wu, Hongwei; Hou, Shaocong; Peng, Ming; Yu, Xiao; Zou, Dechun

2014-02-01

97

Enhanced Photovoltaic Performance of Nanostructured Hybrid Solar Cell Using Highly Oriented TiO2 Nanotubes  

E-print Network

-called third generation of solar cells including dye-sensitized solar cells, DSCs2,3 and organic pho bandgap for better match absorption of the solar spectrum,17 and a hybrid organic/inorganic solar cells (hybrid solar cells), which are composed of an organic donor material and an n-type inorganic

Cao, Guozhong

98

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

PubMed Central

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-?m-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-?m-thick nc-TiO2, and 1.2-?m-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

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

2014-01-01

99

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

NASA Astrophysics Data System (ADS)

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-?m-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-?m-thick nc-TiO2, and 1.2-?m-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%).

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

2014-07-01

100

Laser processing of nanocrystalline TiO2 films for dye-sensitized solar cells  

E-print Network

produced via colloidal synthesis of TiO2 nanoparticles and subsequent deposition of the TiO2 colloidal, Washington, DC 20375 (Received 5 February 2004; accepted 19 May 2004) Pulsed-laser deposition and laser direct-write have been applied to deposit dense (30 nm thick) and porous nanocrystalline TiO2 (nc-TiO2, 5

Arnold, Craig B.

101

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

PubMed Central

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

2013-01-01

102

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

Microsoft Academic Search

Quantum dot-sensitized solar cells based on Zn-doped TiO2 (Zn-TiO2) film photoanode and polysulfide electrolyte were fabricated. Zn-TiO2 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-TiO2\\/CdS film and the photovoltaic performance of the Zn-TiO2\\/CdS cell were investigated. It was found that

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

2010-01-01

103

Highly efficient and completely flexible fiber-shaped dye-sensitized solar cell based on TiO2 nanotube array.  

PubMed

A type of highly efficient completely flexible fiber-shaped solar cell based on TiO(2) nanotube array is successfully prepared. Under air mass 1.5G (100 mW cm(-2)) illumination conditions, the photoelectric conversion efficiency of the solar cell approaches 7%, the highest among all fiber-shaped cells based on TiO(2) nanotube arrays and the first completely flexible fiber-shaped DSSC. The fiber-shaped solar cell demonstrates good flexibility, which makes it suitable for modularization using weaving technologies. PMID:22278314

Lv, Zhibin; Yu, Jiefeng; Wu, Hongwei; Shang, Jian; Wang, Dan; Hou, Shaocong; Fu, Yongping; Wu, Kai; Zou, Dechun

2012-02-21

104

Enhanced photovoltaic performance of dye sensitized solar cells using one dimensional ZnO nanorod decorated porous TiO2 film electrode  

NASA Astrophysics Data System (ADS)

A low cost and effective working electrode with one dimensional ZnO nanorod grown on the porous TiO2 film is used to improve the power conversion efficiency of dye sensitized solar cells. The one dimensional ZnO nanorod is introduced into the porous TiO2 film by a simple and facile hydrothermal route, and the obtained composite film is characterized using the field-emission scan electron microscopy, X-ray diffractometer and photoluminescence spectroscopy. The photocurrent-voltage curves of fabricated dye sensitized solar cells are measured by a solar cell measurement system. Compared with the bare porous TiO2 film based dye sensitized solar cell, it is found that the power conversion efficiency of dye sensitized solar cell with ZnO nanorod decorated TiO2 porous film was improved by more than triple. It is mainly believed that the improved power conversion efficiency of dye sensitized solar cell is ascribed to the increased dye adsorption amount and formation of energy barrier between ZnO nanorod and porous TiO2 film.

Yang, Long; Ma, Qing-lan; Cai, Yungao; Huang, Yuan Ming

2014-02-01

105

Efficient band alignment for ZnxCd1xSe QD-sensitized TiO2 solar cells  

E-print Network

dots (QDs), such as CdS,2,3 CdTe,4­6 PbS,7,8 PbSe,9,10 and InP,11,12 have recently been extensivelyEfficient band alignment for ZnxCd1�xSe QD-sensitized TiO2 solar cells Lin Yang,ab Ru Zhou,a Jolin.6 produced the highest photocurrent and photoconversion efficiency. It demonstrates that the effective band

Cao, Guozhong

106

Overcoming ultraviolet light instability of sensitized TiO2 with meso-superstructured organometal tri-halide perovskite solar cells  

NASA Astrophysics Data System (ADS)

The power conversion efficiency of hybrid solid-state solar cells has more than doubled from 7 to 15% over the past year. This is largely as a result of the incorporation of organometallic trihalide perovskite absorbers into these devices. But, as promising as this development is, long-term operational stability is just as important as initial conversion efficiency when it comes to the development of practical solid-state solar cells. Here we identify a critical instability in mesoporous TiO2-sensitized solar cells arising from light-induced desorption of surface-adsorbed oxygen. We show that this instability does not arise in mesoporous TiO2-free mesosuperstructured solar cells. Moreover, our TiO2-free cells deliver stable photocurrent for over 1,000?h continuous exposure and operation under full spectrum simulated sunlight.

Leijtens, Tomas; Eperon, Giles E.; Pathak, Sandeep; Abate, Antonio; Lee, Michael M.; Snaith, Henry J.

2013-12-01

107

Enhanced photovoltaic performance of a quantum dot-sensitized solar cell using a Nb-doped TiO2 electrode.  

PubMed

In this work Nb-doped anatase TiO2 nanocrystals are used as the photoanode of quantum-dot-sensitized solar cells. A solar cell with CdS/CdSe quantum dots co-sensitized 2.5 mol% Nb-doped anatase TiO2 nanocrystals can achieve a photovoltaic conversion efficiency of 3.3%, which is almost twice as high as the 1.7% obtained by a cell based on undoped TiO2 nanocrystals. The incident photon-to-current conversion efficiency can reach as high as 91%, which is a record for all quantum-dot-sensitized solar cells. Detailed analysis shows that such an enhancement is due to improved lifetime and diffusion length of electrons in the solar cell. PMID:24045808

Jiang, Lei; You, Ting; Deng, Wei-Qiao

2013-10-18

108

Formation of efficient dye-sensitized solar cells by introducing an interfacial layer of hierarchically ordered macro-mesoporous TiO 2 film  

Microsoft Academic Search

Hierarchically ordered macro-mesoporous TiO2 films (Ti-Ma-Me) were fabricated on fluorine-doped tin oxide (FTO) substrates through the confinement self-assembly method.\\u000a The prepared Ti-Ma-Me possesses periodically ordered structure and a large specific surface area, which was applied as an\\u000a interfacial layer between the nanocrystalline TiO2 film (P25-TiO2) and FTO electrode in the dye-sensitized solar cell (DSSC). The introduction of a Ti-Ma-Me interfacial

Jiang Du; XiaoYong Lai; Jonathan E. Halpert; Yu Yang; Dan Wang

2011-01-01

109

Deposition of TiO2 Passivation Layer by Plasma Enhanced Chemical Vapor Deposition between the Transparent Conducting Oxide and Mesoporous TiO2 Electrode in Dye Sensitized Solar Cells  

NASA Astrophysics Data System (ADS)

The characteristic of TiO2 passivation layers grown by plasma enhanced chemical vapor deposition as a function of its thickness on F-doped SnO2 (FTO) electrode was investigated. The thickness of TiO2 passivation layer was varied from 30 to 200 nm by controlling the deposition time. The electric resistance of the TiO2 layers was depended on the thickness, so the optimized thickness in enhancing the connection and reducing the recombination of electrons on the surface of FTO electrode was determined. The dye sensitized solar cells fabricated with 40 nm thick TiO2 passivation layer showed the maximum power conversion efficiency of 6.93%. It was due to the effective connection of mesoporous TiO2 and FTO and the prevention of electron recombination from the FTO to electrolyte. The reduced resistance, enlarged electron diffusion length measured by the electrochemical impedance spectroscopy, intensity-modulated photocurrent spectroscopy and intensity-modulated photovoltage spectroscopy identified the connection and anti-recombination effect.

Lee, Su Young; Kim, Sang Ho

2012-10-01

110

Hydrogen-radical durability of TiO 2 thin films for protecting transparent conducting oxide for Si thin film solar cells  

Microsoft Academic Search

Hydrogen-radical durability of TiO2 thin films has been investigated under conditions for preparing Si thin film solar cells by catalytic chemical vapor deposition method. It is found that the composition and the optical transmittance of TiO2 films are almost the same before and after hydrogen-radical exposures with a filament temperature at approximately 1700 °C and a H2 pressure of approximately

H. Natsuhara; T. Ohashi; S. Ogawa; N. Yoshida; T. Itoh; S. Nonomura; M. Fukawa; K. Sato

2003-01-01

111

Frontside illuminated CdS\\/CdSe quantum dots co-sensitized solar cells based on TiO2 nanotube arrays  

Microsoft Academic Search

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

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

2011-01-01

112

Clean and time-effective synthesis of anatase TiO2 nanocrystalline by microwave-assisted solvothermal method for dye-sensitized solar cells  

NASA Astrophysics Data System (ADS)

In this article, we report a clean and time-effective solvothermal synthesis route using microwave-assisted heating method to prepare nanocrystalline anatase TiO2 with its application for dye-sensitized solar cells. With this proposed method, pure anatase TiO2 nanoparticles with size about 20 nm are successfully obtained at 220 °C for 30 min. Our method of microwave-assisted organic solvothermal route significantly reduces the elaborating process of washing and solvent exchange for the subsequent paste formation. The as-synthesized TiO2 colloidal solution is ready for particle dispersion that markedly simplified the preparation procedures. Material characterizations of the anatase TiO2 nanoparticles are performed by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS), respectively. The photovoltaic performances of the dye-sensitized solar cells assembled with the as-synthesized TiO2 nanocrystallines as photoanodes in various film thicknesses are examined. An excellent energy conversion efficiency of 7.8% is achieved which is comparable to the previously reported dye-sensitized solar cells made of hydrothermal microwave-synthesized TiO2.

Shen, Po-Shen; Tai, Yu-Chuen; Chen, Peter; Wu, Yu-Chun

2014-02-01

113

Incorporation of Mn2+ and Co2+ to TiO2 nanoparticles and the performance of dye-sensitized solar cells  

NASA Astrophysics Data System (ADS)

Dye-sensitized solar cells were fabricated using (Mn and Co) M-doped TiO2 electrodes which were successfully synthesized via the hydrothermal method. Furthermore, the effect of Mn2+ and Co2+ ions content on the properties of TiO2 electrodes was studied. The materials were characterized by XRD, TEM/HRTEM, EDS, BET specific surface area (SBET), pore-size distribution by BJH, UV-Vis Spectroscopy, and their photoconversion efficiencies were evaluated using I-V characterization, IPCE and EIS. X-ray diffraction results reveal both undoped and M-doped TiO2 structure without any impurity phase. The X-ray diffraction patterns of the (Mn and Co) ions doped TiO2 is almost the same as that of pure TiO2, showing that (Mn and Co) have little influence on the formation of anatase titania. The influence of dopant (Mn, Co) ions on band energetics and photoelectrochemical properties of nanostructured TiO2 electrodes was investigated. The total trap densities were remarkably increased as TiO2 electrodes were doped with (Mn and Co). Experiment results showed that the content of M-doped TiO2 plays an important role in the photoelectrochemical properties. The conversion efficiency was decreased with (Mn and Co)-doped TiO2 electrodes under irradiation of 100 mW/cm2 white light due to the high change of flat band edge and the charge recombination which happened related to trap density of TiO2 electrodes with (Mn and Co) ions doping.

Shalan, A. E.; Rashad, M. M.

2013-10-01

114

Efficient hybrid plasmonic polymer solar cells with Ag nanoparticle decorated TiO2 nanorods embedded in the active layer.  

PubMed

A hybrid plasmonic polymer solar cell, in which plasmonic metallic nanostructures (such as Ag, Au, and Pt nanoparticles) are embedded in the active layer, has been under intense scrutiny recently because it provides a promising new approach to enhance the efficiency of the device. We propose a brand new hybrid plasmonic nanostructure, which combines a plasmonic metallic nanostructure and one-dimensional semiconductor nanocrystals, to enhance the photocurrent of the device through a strong localized electric field and an enhanced charge transport channel. We demonstrate that when Ag nanoparticle decorated TiO2 nanorods were introduced into the active layer of polymer-fullerene based bulk heterojunction solar cells, the photocurrent significantly increased to 14.15 mA cm(-2) from 6.51 mA cm(-2) without a decrease in the open voltage; thus, the energy conversion efficiency was dramatically enhanced to 4.87% from 2.57%. PMID:24796321

Liu, Kong; Bi, Yu; Qu, Shengchun; Tan, Furui; Chi, Dan; Lu, Shudi; Li, Yanpei; Kou, Yanlei; Wang, Zhanguo

2014-06-01

115

Efficient hybrid plasmonic polymer solar cells with Ag nanoparticle decorated TiO2 nanorods embedded in the active layer  

NASA Astrophysics Data System (ADS)

A hybrid plasmonic polymer solar cell, in which plasmonic metallic nanostructures (such as Ag, Au, and Pt nanoparticles) are embedded in the active layer, has been under intense scrutiny recently because it provides a promising new approach to enhance the efficiency of the device. We propose a brand new hybrid plasmonic nanostructure, which combines a plasmonic metallic nanostructure and one-dimensional semiconductor nanocrystals, to enhance the photocurrent of the device through a strong localized electric field and an enhanced charge transport channel. We demonstrate that when Ag nanoparticle decorated TiO2 nanorods were introduced into the active layer of polymer-fullerene based bulk heterojunction solar cells, the photocurrent significantly increased to 14.15 mA cm-2 from 6.51 mA cm-2 without a decrease in the open voltage; thus, the energy conversion efficiency was dramatically enhanced to 4.87% from 2.57%.

Liu, Kong; Bi, Yu; Qu, Shengchun; Tan, Furui; Chi, Dan; Lu, Shudi; Li, Yanpei; Kou, Yanlei; Wang, Zhanguo

2014-05-01

116

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

PubMed

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

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

117

Funnel-structured TiO2 electrode for improved charge extraction in dye-sensitized solar cell  

NASA Astrophysics Data System (ADS)

We here show that the current density and efficiency of dye-sensitized solar cell (DSSC) can be much enhanced by generating more bulky-structured funnels inside the typical TiO2 electrode. This approach is fundamentally based on the pulsed laser-induced desorption and melting of TiO2 nanoparticles. Three-beam interference was utilized to fabricate the periodic electrode structure. While the dye coverage was little influenced by this process because a small volume fraction of the electrode was converted into the bulky structure, the photoexcited electrons could be more effectively extracted owing to the prolonged diffusion length. As a result, the photocurrent density and efficiency of DSSCs were much improved. The enhancement of both factors was reliably ascertained by the multiple-cell characterization. The funnel cells exhibited an average short-circuit current density of 19.77 mA/cm2 and an efficiency of 9.44%, while 17.30 mA/cm2 and 8.27% were obtained from the reference cells.

Jin, Minhea; Lee, Myeongkyu

2013-10-01

118

Improved Energy Conversion Efficiency of TiO2 Thin Films Modified with Ta2O5 in Dye-Sensitized Solar Cells  

NASA Astrophysics Data System (ADS)

Tantalum-doped TiO2 thin films [(TiO2)1-x(Ta2O5)x, x=0-0.8%] were prepared on fluorine-doped tin oxide (FTO)-coated substrates by sol-gel technology for uses in dye-sensitized solar cells (DSSCs). The effects of Ta content on the growth and properties of the TiO2 thin films were investigated. The crystallization and microstructures of the thin films were examined by X-ray diffraction, scanning electron microscopy, and Brunauer-Emmett-Teller analyses. The performance of DSSCs based on Ta-doped TiO2 thin films was also studied. From the obtained results, the increases in Jsc and Voc may be due to the increased electron concentration of TiO2 thin film and the flat-band potential of the TiO2 shifted by tantalum doping, respectively. The optimum properties of DSSCs of Voc=0.68 V, Jsc=7.84 mA/cm2, FF=45.1%, and ?=2.4% were obtained using the Ta-doped TiO2 thin film with x=0.5%.

Kao, Ming-Cheng; Chen, Hone-Zern; Young, San-Lin

2013-01-01

119

Laser welding of nanoparticulate TiO2 and transparent conducting oxide electrodes for highly efficient dye-sensitized solar cell.  

PubMed

Poor interfacial contact is often encountered in nanoparticulate film-based devices. The dye-sensitized solar cell (DSSC) is a representative case in which a nanoporous TiO(2) electrode needs to be prepared on the transparent conducting oxide (TCO)-coated glass substrate. In this study, we demonstrate that the inter-electrode contact resistance accounts for a considerable portion of the total resistance of a DSSC and its efficiency can be greatly enhanced by welding the interface with a laser. TiO(2) films formed on the TCO-coated glass substrate were irradiated with a pulsed ultraviolet laser beam at 355 nm; this transmits through the TCO and glass but is strongly absorbed by TiO(2). Electron microscopy analysis and impedance measurements showed that a thin continuous TiO(2) layer is formed at the interface as a result of the local melting of TiO(2) nanoparticles and this layer completely bridges the gap between the two electrodes, improving the current flow with a reduced contact resistance. We were able to improve the efficiency by 35-65% with this process. DSSCs fabricated using a homemade TiO(2) paste revealed an efficiency improvement from eta = 3.3% to 5.4%, and an increase from 8.2% to 11.2% was achieved with the TiO(2) electrodes made from a commercial paste. PMID:20671364

Kim, Jinsoo; Kim, Jonghyun; Lee, Myeongkyu

2010-08-27

120

Effect of anodic aluminum oxide template imprinting on TiO2 blocking layer of flexible dye-sensitized solar cell.  

PubMed

In this paper, we have proposed a new flexible dye-sensitized solar cell (DSSC) structure that employs an Anodic Aluminum Oxide (AAO) template imprinted TiO2 blocking layer, in which the AAO template creates TiO2 nano-particle aggregated islands on the TiO2 blocking layer. The TiO2 blocking layer prevents charge recombination between the metal foil and the liquid electrolyte. TiO2 nano-particle aggregated islands improve the scattering of incident light during back illumination and provide the wider surface area, yielding enhanced power conversion efficiency (PCE). All the flexible DSSC structure with TiO2 nano-particle aggregated islands on the TiO2 blocking layer exhibited higher photocurrent than did conventional DSSC because light that passed through the photoanode was scattered, thereby giving it improved PCE that was as much as 23% higher than that of a conventional DSSC. This proposed method is an effective manufacturing process for flexible DSSC. PMID:23755613

Kim, Kang-Pil; Lee, Sang-Ju; Kim, Dae-Hwan; Hwang, Dae-Kue

2013-03-01

121

Efficient PbS/CdS co-sensitized solar cells based on TiO2 nanorod arrays  

NASA Astrophysics Data System (ADS)

Narrow bandgap PbS nanoparticles, which may expand the light absorption range to the near-infrared region, were deposited on TiO2 nanorod arrays by successive ionic layer adsorption and reaction method to make a photoanode for quantum dot-sensitized solar cells (QDSCs). The thicknesses of PbS nanoparticles were optimized to enhance the photovoltaic performance of PbS QDSCs. A uniform CdS layer was directly coated on previously grown PbS-TiO2 photoanode to protect the PbS from the chemical attack of polysulfide electrolytes. A remarkable short-circuit photocurrent density (approximately 10.4 mA/cm2) for PbS/CdS co-sensitized solar cell was recorded while the photocurrent density of only PbS-sensitized solar cells was lower than 3 mA/cm2. The power conversion efficiency of the PbS/CdS co-sensitized solar cell reached 1.3%, which was beyond the arithmetic addition of the efficiencies of single constituents (PbS and CdS). These results indicate that the synergistic combination of PbS with CdS may provide a stable and effective sensitizer for practical solar cell applications.

Li, Yitan; Wei, Lin; Chen, Xiya; Zhang, Ruizi; Sui, Xing; Chen, Yanxue; Jiao, Jun; Mei, Liangmo

2013-02-01

122

Green Organic Solar Cells from a Water-Soluble Polymer and Nanocrystalline TiO 2  

Microsoft Academic Search

Next generation organic solar cells offer a solution to the limitations of silicon through the vision of low-cost, liquid-based, large area fabrication technology based on polymer and nanomaterials at room temperature. However, most polymers used in solar cells are dissolved in organic solvents such as xylene, toluene, chloroform, and chlorobenzene. Such solvents are harmful to people and environments, leading to

Syed Ashraf

123

Verification of the current voltage characteristics and efficiencies in dye-sensitized TiO2 solar cells  

NASA Astrophysics Data System (ADS)

Recently, a paper was published by the Lausanne Group headed by Dr. M. Gratzel which claimed to obtain a low cost 7% efficient photoelectrochemical solar cell from a Ru carboxylated bipyridyl charge transfer dye adsorbed on the very rough surface of a colloidal TiO2 film. In the current paper, a verification of this result is presented as well as the requirements for efficient collection in this new type of cell. Measurements are reported in simulated and natural sunlight which confirm that the efficiency is indeed in the range previously reported. In addition, a comparison will be made with detailed balance type calculations which support that the cell operates within the limits defined by thermodynamics and the optical absorption of the adsorbed dye. A discussion is made as to the use of the sensitization concept with other materials as well as to the basic economics of such a device.

Smestad, Greg P.

1993-10-01

124

Comparative study of plasma and ion-beam treatment to reduce the oxygen vacancies in TiO 2 and recombination reactions in dye-sensitized solar cells  

NASA Astrophysics Data System (ADS)

Oxygen plasma and ion-beam treatments of nano-structured TiO 2 were carried out to enhance the efficiency of dye-sensitized solar cells (DSSCs). Relative changes in surface states and recombination reactions were examined. Comparative studies showed that the oxygen ion-beam treatment was more effective in reducing the number of oxygen vacancies in TiO 2 and the recombination reactions between TiO 2 conduction band electrons and I3- ions in the electrolyte than the plasma treatment. Oxygen ion-beam treated TiO 2 film in the DSSC showed a 23 mV increase in the open-circuit voltage ( Voc) and an improvement in the photo-conversion efficiency from 5.05% to 6.64%.

Parvez, Md. Khaled; Yoo, Gi Moon; Kim, Ju Ho; Ko, Min Jae; Kim, Sung Ryong

2010-07-01

125

Multifunctional graded index TiO2 compact layer for performance enhancement in dye sensitized solar cell  

NASA Astrophysics Data System (ADS)

A specially tailored index TiO2 compact layer (arc-TiO2) has been successfully deposited to serve as photoanode of a dye-sensitized solar cell (DSSC) by radio-frequency magnetron sputtering. The employment of the TiO2 compact layer in the DSSC was systematically investigated by means of UV-absorption spectra, incident photon to current efficiency (IPCE), open-circuit voltage decay (OCVD) and electrochemical impedance spectroscopy (EIS). The higher and red-shifted transmittance spectra of the ITO/arc-TiO2 electrode mimic the IPCE spectra of the DSSC, in a specific wavelength region. Furthermore, the blue-shift of the UV-absorption spectra and lower R1 value obtained from EIS measurements implied the decrease of the charge interfacial resistance, and this consequently facilitates the charge transport from the nanocrystalline-TiO2 to the ITO. The integrated effects of the arc-TiO2 compact layer originate the remarkable improvement in this type of DSSC applications. As a result, the arc-TiO2-based DSSC showed higher conversion efficiency of about 4.38%, representing almost 53% increment compared to bare ITO cell. This work also discuss the fundamental insight of the compact layer that determines the origin of such improvement in the DSSC performance.

Abdullah, M. H.; Rusop, M.

2013-11-01

126

ENHANCEMENT IN NANOCRYSTALLINE TiO2 SOLAR CELLS SENSITIZED WITH ZnPc BY NANOPARTICLES  

Microsoft Academic Search

This work discusses a ZnPc composite in dye-sensitized solar cells (DSSCs). The enhanced performance of solar cells is due to the role of gold nanoparticles (GNPs), ZnSe quantum dots (QDs), and carbon nanotubes (CNTs) to increase the energy conversion efficiency. Both charge separation effect by GNPs and driving force effect by ZnSe QDs can improve the efficiency of cells, and

LUNG-CHIEN CHEN; CHUNG-CHIEH WANG; BO-SHIANG TSENG

127

Synthesis of TiO2 nanotube arrays and its application in mini-3D dye-sensitized solar cells  

NASA Astrophysics Data System (ADS)

Here we report a mini-three-dimensional dye-sensitized solar cell (3D DSSC) based on TiO2 nanotube arrays (TNAs). TNAs were directly grown on spiral-shaped titanium wire via a facile potentiostatic anodization. Furthermore, the TNAs film was characterized by scanning electron microscopy, x-ray diffraction and transmission electron microscopy, indicating that the annealed TNAs were composed of single-crystalline anatase particles. Unlike conventional flat DSSC, this mini-3D DSSC could easily hold liquid electrolyte due to the capillary force which facilitated sealing the cell. This mini-3D DSSC showed an energy conversion efficiency of 4.1% under the AM 1.5 condition, which was much higher compared with that (3.2%) of the backside illuminated TNAs based DSSC of the same projected area.

Liu, Yong; Li, Ming; Wang, Hai; Zheng, Jiemin; Xu, Hongmei; Ye, Qihong; Shen, Hui

2010-05-01

128

Frontside illuminated TiO2 nanotube dye-sensitized solar cells using multifunctional microchannel array electrodes  

NASA Astrophysics Data System (ADS)

Here we report a frontside illuminated TiO2 nanotube based dye-sensitized solar cell (DSSC). The photoanode with inclined microchannels (IMCs) formed by laser drilling acted as a multifunctional role for enhancing the cell's efficiency; light trapping, pathway for transporting electrolyte, and extra surface area for dye loading. The amount of N719 dye absorbed on IMCs photoanode was measured to be 3.83×10-7 mol/cm2, which was almost 1.82 times as high as that of the flat photoanode. The frontside illuminated DSSC showed an energy conversion efficiency of 4.1% under AM1.5 condition, which was much higher compared to that (3.1%) of the backside illuminated DSSC.

Liu, Yong; Wang, Hai; Li, Ming; Hong, Ruijiang; Ye, Qihong; Zheng, Jiemin; Shen, Hui

2009-12-01

129

Spray pyrolysed microporous TiO2 thin films by optimisation of substrate temperature for ‘all sprayed’ solar cells  

NASA Astrophysics Data System (ADS)

Titanium dioxide thin films were deposited on glass substrate at temperatures ranging from 300 °C to 500 °C by a simple, cost effective spray pyrolysis method using commercially available TiO2 powder (Degussa P25). Analyses using scanning electron microscopy (SEM) and atomic force microscopy (AFM) reveal the microporous nature of the films at 350 °C. X-ray diffraction (XRD) and Raman studies reveal that these films are amorphous in nature. The films were subsequently annealed at 500 °C for 2 h, resulting in crystallisation (the tetragonal anatase phase). XPS analysis was effectively used to study the chemical composition of the samples. Finally, optimized microporous TiO2 thin films were used for the fabrication of an ‘all-sprayed’ solar cell utilizing well-established CuInS2 as the absorber layer. The best device under this study has an open-circuit voltage of 409 mV and a short-circuit current density of 3.90 mA cm?2. The efficiency and fill factor were 0.61% and 38%, respectively.

Santhosh, M. V.; Deepu, D. R.; Geethu, R.; Rajeev Kumar, K.; Sudha Kartha, C.; Vijayakumar, K. P.

2014-11-01

130

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

PubMed

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

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

2013-12-01

131

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

PubMed

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 ?m 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

Tsai, Jenn Kai; Hsu, Wen Dung; Wu, Tian Chiuan; Meen, Teen Hang; Chong, Wen Jie

2013-01-01

132

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

NASA Astrophysics Data System (ADS)

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 ?m 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.

Tsai, Jenn Kai; Hsu, Wen Dung; Wu, Tian Chiuan; Meen, Teen Hang; Chong, Wen Jie

2013-11-01

133

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

NASA Astrophysics Data System (ADS)

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 ?m 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.

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

2011-10-01

134

Enhancement of photovoltaic performance in dye-sensitized solar cells with the spin-coated TiO2 blocking layer.  

PubMed

The TiO2 thin film layers were introduced with the spin-coating method between FTO electrode and TiO2 photoanode in dye sensitized solar cell (DSSC) to prevent electron back migration from the FTO electrode to electrolyte. The DSSC containg different thickness of TiO2 thin film (10-30, 40-60 and 120-150 nm) were prepared and photovoltaic performances were analysed with /-Vcurves and electrochemical impedance spectroscopy. The maximum cell performance was observed in DSSC with 10-30 nm of TiO2 thin film thickness (11.92 mA/cm2, 0.74 V, 64%, and 5.62%) to compare with that of pristine DSSC (11.09 mA/cm2, 0.65 V, 62%, and 4.43%). The variation of photoelectric conversion efficiency of the DSSCs with different TiO2 thin film thickness was discussed with the analysis of crystallographic and microstructural properties of TiO2 thin films. PMID:22966702

Lee, Jeong Gwan; Cheon, Jong Hun; Yang, Hyeon Seok; Lee, Do Kyung; Kim, Jae Hong

2012-07-01

135

Combined embedding of N-doping and CaCO3 surface modification in the TiO2 photoelectrodes for dye-sensitized solar cells  

NASA Astrophysics Data System (ADS)

A successive embedding of N-doping and CaCO3 surface modification was carried out in the TiO2 photoelectrodes for dye-sensitized solar cells (DSSCs). The combined effect was revealed with the great increase of the open-circuit voltage (Voc), short-circuit current (Jsc), and photoelectric conversion efficiency (?) of the prepared cells; the efficiency (?) was improved from 5.42% of a commercial TiO2 photoelectrode to 7.47% of an unmodified N-doped electrode, and to 9.03% of a N-doped and CaCO3 surface modified electrode. An enhanced photoresponse in N-doped TiO2 nanoparticles generate more photo-excited electrons in adsorbed dye, as supported by measured UV-vis diffuse reflectance spectra and incident photon to current conversion efficiency (IPCE). A successive CaCO3 surface modification then form a barrier on the surface of N-doped TiO2 particles, suppressing charge recombination of photo-generated electrons from N-doped TiO2 to dye or electrolyte, and thus extending their life time in the electrode, as supported by electron impedance spectroscopy (EIS). Furthermore, the higher basicity of the CaCO3 modified TiO2 facilitates the dye adsorption, as supported by the direct measurement of the amount of adsorbed dye.

Park, Su Kyung; Yun, Tae Kwan; Bae, Jae Young; Won, Yong Sun

2013-11-01

136

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

NASA Astrophysics Data System (ADS)

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 ?m 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.

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

2013-05-01

137

One-dimensional and (001) facetted nanostructured TiO2 photoanodes for dye-sensitized solar cells.  

PubMed

As one of the most important components in dye-sensitized solar cells (DSCs), photoanode materials have attracted massive interest and been greatly developed through the efforts of various research institutions in recent years. Photoanode materials not only provide a large surface for the sensitizer to favor charge separation, but also conduct the electrons to the collection electrode. In recent years, one-dimensional (1D) nanostructures (nanotubes (NT), nanowires (NW) and nanorods(NR)), which offer direct pathways for electron transport, and nanostructures (nanosheets (NS) and nanoparticles (NP)) with (001) crystal facets which possess higher surface energies have been widely employed as photoanode materials. In this review, the progress of 1D nanostructures and those with (001) crystal facets, as well as their photovoltaic performance in DSCs will be discussed briefly. Further efforts are needed to provide theoretical research for 1D and (001) facet nanostructured TiO2 and to improve DSC performances based on these photoanodes. PMID:23574952

Lin, Hong; Wang, Xiao; Hao, Feng

2013-01-01

138

Efficient Natural Dye-Sensitized Solar Cells Based on Spin-Coated TiO2 Anode Materials  

NASA Astrophysics Data System (ADS)

TiO2 anode materials are prepared on ITO glass by spin-coated method. Dye-sensitized solar cells are assembled with these anodes and natural dyes extracted from radix ophiopogonis by different solvents. The formation and characterization of anode materials are confirmed by field-emission scanning electron microscopy, x-ray diffraction, UV-visible absorption spectroscopy. Photovoltaic testing results show that energy conversion efficiency could reach 1.67% with fill factor of 0.51, open-circuit voltage of 457 mV, and short-circuit photocurrent density of 7.2 mA/cm2. The short-circuit photocurrent density can reach 7.6 mA/cm2 with efficiency of 1.33.

Yu, Xiao-Hong; Sun, Zhao-Zong; Lian, Jie; Li, Yi-Tan; Chen, Yan-Xue; Gao, Shang; Wang, Xiao; Wang, Ying-Shun; Zhao, Ming-Lin

2013-11-01

139

Flexible TiO2 nanotube-based dye-sensitized solar cells using laser-drilled microhole array electrodes  

NASA Astrophysics Data System (ADS)

Here we report on the growth of TiO2 nanotube arrays (TNAs) on Ti foil with laser-drilled microhole arrays (MHAs). The MHAs promoted the adhesion of the TNA film to Ti substrate, which is well suited for flexible dye-sensitized solar cells (DSSCs). The MHA photoanode and TNAs were characterized by SEM, 3D optical profiling, XRD and TEM. For such a flexible MHA photoanode, the TNA-based DSSC was assembled using a platinized conductive glass counter electrode, and a conversion efficiency of 3.45% was achieved under AM 1.5 condition. A flexible TNA-based DSSC was also fabricated using a flexible MHA photoanode combined with a platinized indium tin oxide-polyethylene naphthalate counter electrode, which achieved 2.67% photovoltaic conversion efficiency under simulated AM 1.5 sunlight.

Liu, Yong; Xu, Hongmei; Wang, Hai; Zhao, Wenxia; Liang, Chaolun; Zhong, Minyi; Shen, Hui

2011-01-01

140

Increases in solar conversion efficiencies of the ZrO2 nanofiber-doped TiO2 photoelectrode for dye-sensitized solar cells  

NASA Astrophysics Data System (ADS)

In this paper, in order to improve the efficiency of dye-sensitized solar cells, we introduced zirconia [ZrO2] nanofibers into a mesoporous titania [TiO2] photoelectrode. The photoelectrode consists of a few weight percent of ZrO2 nanofibers and a mesoporous TiO2 powder. The mixed ZrO2 nanofibers and the mesoporous TiO2 powder possessed a larger surface area than the corresponding mesoporous TiO2 powder. The optimum ratio of the ZrO2 nanofiber was 5 wt.%. The 5 wt.% ZrO2-mixed device could get a short-circuit photocurrent density of 15.9 mA/cm2, an open-circuit photovoltage of 0.69 V, a fill factor of 0.60, and a light-to-electricity conversion efficiency of 6.5% under irradiation of AM 1.5 (100 mW/cm2).

Wang, Jiao; Mei Jin, En; Park, Ju-Young; Wang, Wan Lin; Guan Zhao, Xing; Gu, Hal-Bon

2012-02-01

141

Increases in solar conversion efficiencies of the ZrO2 nanofiber-doped TiO2 photoelectrode for dye-sensitized solar cells  

PubMed Central

In this paper, in order to improve the efficiency of dye-sensitized solar cells, we introduced zirconia [ZrO2] nanofibers into a mesoporous titania [TiO2] photoelectrode. The photoelectrode consists of a few weight percent of ZrO2 nanofibers and a mesoporous TiO2 powder. The mixed ZrO2 nanofibers and the mesoporous TiO2 powder possessed a larger surface area than the corresponding mesoporous TiO2 powder. The optimum ratio of the ZrO2 nanofiber was 5 wt.%. The 5 wt.% ZrO2-mixed device could get a short-circuit photocurrent density of 15.9 mA/cm2, an open-circuit photovoltage of 0.69 V, a fill factor of 0.60, and a light-to-electricity conversion efficiency of 6.5% under irradiation of AM 1.5 (100 mW/cm2). PMID:22297154

2012-01-01

142

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

PubMed

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 ?m 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

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

2013-12-26

143

The influence of anatase-rutile mixed phase and ZnO blocking layer on dye-sensitized solar cells based on TiO2nanofiberphotoanodes  

NASA Astrophysics Data System (ADS)

High performance is expected in dye-sensitized solar cells (DSSCs) that utilize one-dimensional (1-D) TiO2 nanostructures owing to the effective electron transport. However, due to the low dye adsorption, mainly because of their smooth surfaces, 1-D TiO2 DSSCs show relatively lower efficiencies than nanoparticle-based ones. Herein, we demonstrate a very simple approach using thick TiO2 electrospun nanofiber films as photoanodes to obtain high conversion efficiency. To improve the performance of the DSCCs, anatase-rutile mixed-phase TiO2 nanofibers are achieved by increasing sintering temperature above 500°C, and very thin ZnO films are deposited by atomic layer deposition (ALD) method as blocking layers. With approximately 40-?m-thick mixed-phase (approximately 15.6 wt.% rutile) TiO2 nanofiber as photoanode and 15-nm-thick compact ZnO film as a blocking layer in DSSC, the photoelectric conversion efficiency and short-circuit current are measured as 8.01% and 17.3 mA cm-2, respectively. Intensity-modulated photocurrent spectroscopy and intensity-modulated photovoltage spectroscopy measurements reveal that extremely large electron diffusion length is the key point to support the usage of thick TiO2 nanofibers as photoanodes with very thin ZnO blocking layers to obtain high photocurrents and high conversion efficiencies.

Ding, Jianning; Li, Yan; Hu, Hongwei; Bai, Li; Zhang, Shuai; Yuan, Ningyi

2013-01-01

144

The influence of anatase-rutile mixed phase and ZnO blocking layer on dye-sensitized solar cells based on TiO2nanofiberphotoanodes  

PubMed Central

High performance is expected in dye-sensitized solar cells (DSSCs) that utilize one-dimensional (1-D) TiO2 nanostructures owing to the effective electron transport. However, due to the low dye adsorption, mainly because of their smooth surfaces, 1-D TiO2 DSSCs show relatively lower efficiencies than nanoparticle-based ones. Herein, we demonstrate a very simple approach using thick TiO2 electrospun nanofiber films as photoanodes to obtain high conversion efficiency. To improve the performance of the DSCCs, anatase-rutile mixed-phase TiO2 nanofibers are achieved by increasing sintering temperature above 500°C, and very thin ZnO films are deposited by atomic layer deposition (ALD) method as blocking layers. With approximately 40-?m-thick mixed-phase (approximately 15.6?wt.% rutile) TiO2 nanofiber as photoanode and 15-nm-thick compact ZnO film as a blocking layer in DSSC, the photoelectric conversion efficiency and short-circuit current are measured as 8.01% and 17.3?mA?cm?2, respectively. Intensity-modulated photocurrent spectroscopy and intensity-modulated photovoltage spectroscopy measurements reveal that extremely large electron diffusion length is the key point to support the usage of thick TiO2 nanofibers as photoanodes with very thin ZnO blocking layers to obtain high photocurrents and high conversion efficiencies. PMID:23286741

2013-01-01

145

Nano-porous TiO2 layer using ultrafine nano-particles for the blocking layer in dye-sensitized solar cells.  

PubMed

A nano-porous TiO2 layer was produced by spray-deposition using ultrafine anatase nano-particles for the blocking layer for the dye-sensitized solar cells (DSCs). The microstructure and the electrochemical properties of the spray-deposited TiO2 layer were examined. The results of electrochemical properties showed that the spray-deposited TiO2 layer was capable to suppress the I3- ions diffusion to FTO substrate, reducing the electron recombination between the electrons on FTO substrate and I3- ions in electrolyte. In addition, the connection between TiO2 film and FTO substrate was improved by the TiO2 layer. Therefore, the short circuit current density and thereby the photo-to-electric energy conversion efficiency were improved by this blocking layer. The blocking effect of the porous layer was attributed to both the complicated pore structure of the spray-deposited layer and the enhanced connections between TiO2 film and FTO substrate. The low temperature characteristic of spray deposition approach indicates that it is suitable to the flexible-based DSCs. PMID:24734697

Yao, Hai-Long; Ma, Jun-Hua; Yang, Guan-Jun; He, Xue-Long; Fan, Sheng-Qiang; Li, Cheng-Xin; Li, Chang-Jiu

2014-04-01

146

Manipulation of inter-particle interactions between TiO2 and CdTe: an effective method to enhance the performance of quantum dot sensitized solar cells  

NASA Astrophysics Data System (ADS)

We have reported a pH-controlled deposition method to directly assemble aqueous 1-thioglycerol and 3-mercaptopropionic acid capped CdTe quantum dots (QDs) on mesoporous TiO2 thin films. The inter-particle interactions between CdTe QDs and mesoporous TiO2 could be modulated with the adjustment of solution pH values. Low amount of QD loading on the mesoporous TiO2 film was observed in the case of electrostatic attraction or strong electrostatic repulsion between CdTe QDs and TiO2. Only at weak electrostatic repulsion between CdTe QDs and TiO2 were high loading and uniform distribution of CdTe QDs obtained on the TiO2 film. Under an optimal condition, a power conversion efficiency of 0.76% was achieved for the CdTe QD sensitized solar cells under the standard illumination condition of simulated AM 1.5G (100 mW cm-2).

Lin, Xiaoyan; Wang, Chunlei; Xu, Shuhong; Cui, Yiping

2014-01-01

147

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

PubMed Central

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

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

2014-01-01

148

Controlling the Morphology of TiO2 Nanorods/Polythiophene Composites for Bulk Heterojunction Solar Cells Using H-Bonding  

NASA Astrophysics Data System (ADS)

We demonstrate how the morphology of solution-processable hybrid bulk heterojunction solar cells, within an active layer consisting of modified poly(3-hexylthiophene) (P3HT) and TiO2 nanorods, can be controlled by H-Bonding. The hybrid bulk heterojunction solar cells suffer from the problems of the aggregation of inorganic nanocrystals and the interface between nanocrystals and the polymer matrix. To address these issues, we utilize P3HT-based block copolymer (BCP), in which one block is P3HT and the other block is a P3HT derivative containing a poly(ethylene glycol) (PEG) oligomer side chain. In the mean time, we functionalized the TiO2 nanorods with dyes having multiple COOH groups. This design both enables self-assembly of the devices via micophase segregation into well-defined morphologies and provides a means for establishing strong preferential interaction between TiO2 nanorods and the PEG side chain. This strong, preferential H-bonding limits the aggregation of the TiO2 nanorods and modifies the interfacial properties between donor and acceptor. TEM showed the self-assembly structure of the TiO2 nanorods in polymer matrix. Using this modified thiophene copolymer, hybrid devices are made with power conversion efficiencies 50% higher than that of conventional P3HT homopolymer.

Lin, Ying; Wei, Qingshuo; Watkins, James J.

2012-02-01

149

Effect of dye-sensitized solar cells based on the anodizing TiO2 nanotube array/nanoparticle double-layer electrode  

NASA Astrophysics Data System (ADS)

Highly ordered TiO2 nanotube arrays fabricated by anodization are very attractive for dye-sensitized solar cells owing to their superior charge percolation and slower charge recombination. Highly ordered, vertically aligned TiO2 nanotube arrays have been prepared by a three-step anodic oxidation. In this work, we considered the aforementioned strategies to improve the efficiency of dye-sensitized solar cells. Employing one of these approaches, the use of oxide semiconductors in the form of a TiO2 nanotube array was attempted as a novel means of improving the electron transport through the film. We fabricated a novel TiO2 nanoparticle/TiO2 nanotube array double-layer photoelectrode by a layer-by-layer assembly process, and we thoroughly investigated the effect of various structures on sample efficiency. Dye-sensitized solar cells with a light-to-electric energy conversion efficiency of 5.48% were achieved at a simulated solar light irradiation of 100 mW/cm2 (AM 1.5).

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

2014-11-01

150

Application of highly-ordered TiO2 nanotube-arrays in heterojunction dye-sensitized solar cells  

NASA Astrophysics Data System (ADS)

Highly-ordered TiO2 nanotube arrays are made by potentiostatic anodization of a titanium film in a fluoride containing electrolyte. Here we describe the application of this unique material architecture in both front-side and back-side illuminated dye-sensitized solar cells (DSSCs). The back-side illuminated solar cells are based on the use of 6.2 µm long (110 nm pore diameter, 20 nm wall thickness) highly-ordered nanotube-array films made by anodization of a 250 µm thick Ti foil in a KF electrolyte. Front-side illuminated solar cells use a negative electrode composed of optically transparent nanotube arrays, approximately 3600 nm in length (46 nm pore diameter, 17 nm wall thickness), grown on a fluorine doped tin oxide coated glass substrate by anodic oxidation of a previously deposited RF-sputtered titanium thin film in a HF electrolyte. After crystallization by oxygen annealling the nanotube-arrays are treated with TiCl4 to enhance photocurrent amplitudes. The arrays are then sensitized by a self-assembled monolayer of bis(tetrabutylammonium)-cis-(dithiocyanato)-N, N'- bis(4-carboxylato-4'-carboxylic acid-2, 2'-bipyridine)ruthenium(II) (commonly called 'N719'). Superior photoresponse is obtained using acetonitrile as the dye solvent. Voltage decay measurements indicate that the highly-ordered TiO2 nanotube-arrays, in comparison with nanoparticulate systems, provide excellent pathways for electron percolation with superior electron lifetimes. The front-side illuminated DSSCs, show a typical AM 1.5 photocurrent of 10.3 mA cm-2, open circuit voltage of 0.84 V, 0.54 fill factor, and 4.7% efficiency although the transparent nanotube-array negative electrode is only 360 nm thick. The back-side illuminated DSSCs show an AM 1.5 short-circuit current density of 10.6 mA cm-2, 0.82 V open circuit potential and a 0.51 fill factor yielding a solar conversion efficiency of 4.4%.

Paulose, Maggie; Shankar, Karthik; Varghese, Oomman K.; Mor, Gopal K.; Grimes, Craig A.

2006-06-01

151

The influence of the time-of-flight mobility on the efficiency of solid-state dye-sensitized TiO2 solar cells  

Microsoft Academic Search

The dependence of zero field charge carrier mobilities obtained from time-of-flight (TOF) measurements for a series of doped triphenyldiamines on trap depth and concentration were determined. The influence of these mobilities on the solar cell characteristics have been studied by measuring I-V characteristics and IPCE values using the same doped hole conductors in solid-state dye-sensitized TiO2 solar cells. The traps

C. Jäger; D. Haarer; B. Peng; M. Thelakkat

2004-01-01

152

Stable anatase TiO2 coating on quartz fibers by atomic layer deposition for photoactive light-scattering in dye-sensitized solar cells  

NASA Astrophysics Data System (ADS)

Quartz fibers provide a unique high surface-area substrate suitable for conformal coating using atomic layer deposition (ALD), and are compatible with high temperature annealing. This paper shows that the quartz fiber composition stabilizes ALD TiO2 in the anatase phase through TiO2-SiO2 interface formation, even after annealing at 1050 °C. When integrated into a dye-sensitized solar cell, the TiO2-coated quartz fiber mat improves light scattering performance. Results also confirm that annealing at high temperature is necessary for better photoactivity of ALD TiO2, which highlights the significance of quartz fibers as a substrate. The ALD TiO2 coating on quartz fibers also boosts dye adsorption and photocurrent response, pushing the overall efficiency of the dye-cells from 6.5 to 7.4%. The mechanisms for improved cell performance are confirmed using wavelength-dependent incident photon to current efficiency and diffuse light scattering results. The combination of ALD and thermal processing on quartz fibers may enable other device structures for energy conversion and catalytic reaction applications.

Kim, Do Han; Koo, Hyung-Jun; Jur, Jesse S.; Woodroof, Mariah; Kalanyan, Berç; Lee, Kyoungmi; Devine, Christina K.; Parsons, Gregory N.

2012-07-01

153

Nanostructured CuO Films on Copper: Fabrication and Application as a Cathode in Dye-Sensitized TiO2 Solar Cells  

Microsoft Academic Search

Nanostructured CuO films are grown on copper substrates by a wet chemical method in a water bath. It has been successfully used as a cathode for dye-sensitized TiO2 nanoparticle solar cells. The effects of reaction temperature, time, and pH on the film properties and solar energy conversion have been investigated. Under favorable conditions, we obtain a short circuit current density

Qiudi Liu; S. Anandan; S. H. Yang; W. K. Ge

2006-01-01

154

Highly ordered and vertically oriented TiO2/Al2O3 nanotube electrodes for application in dye-sensitized solar cells.  

PubMed

The surface of long TiO2 nanotube (NT) electrodes in dye-sensitized solar cells (DSSCs) was modified without post-annealing by using atomic layer deposition (ALD) for the enhancement of photovoltage. Vertically oriented TiO2 NT electrodes with highly ordered and crack-free surface structures over large areas were prepared by a two-step anodization method. The prepared TiO2 NTs had a pore size of 80 nm, and a length of 23 ?m. Onto these TiO2 NTs, an Al2O3 shell of a precisely controlled thickness was deposited by ALD. The conformally coated shell layer was confirmed by high-resolution transmission electron microscopy, energy-dispersive x-ray spectroscopy, and x-ray photoelectron spectroscopy. The open-circuit voltage (Voc) of the DSSCs was gradually enhanced as the thickness of the Al2O3 shell of the TiO2/Al2O3 NT electrodes was increased, which resulted from the enhanced electron lifetime. The enhanced electron lifetime caused by the energy barrier effect of the shell layer was measured quantitatively by the open-circuit voltage decay technique. As a result, 1- and 2-cycle-coated samples showed enhanced conversion efficiencies compared to the bare sample. PMID:25426725

Kim, Jae-Yup; Lee, Kyeong-Hwan; Shin, Junyoung; Park, Sun Ha; Kang, Jin Soo; Han, Kyu Seok; Sung, Myung Mo; Pinna, Nicola; Sung, Yung-Eun

2014-12-19

155

Hierarchical rutile TiO2 flower cluster-based high efficiency dye-sensitized solar cells via direct hydrothermal growth on conducting substrates.  

PubMed

Dye-sensitized solar cells (DSSCs) based on hierarchical rutile TiO(2) flower clusters prepared by a facile, one-pot hydrothermal process exhibit a high efficiency. Complex yet appealing rutile TiO(2) flower films are, for the first time, directly hydrothermally grown on a transparent conducting fluorine-doped tin oxide (FTO) substrate. The thickness and density of as-grown flower clusters can be readily tuned by tailoring growth parameters, such as growth time, the addition of cations of different valence and size, initial concentrations of precursor and cation, growth temperature, and acidity. Notably, the small lattice mismatch between the FTO substrate and rutile TiO(2) renders the epitaxial growth of a compact rutile TiO(2) layer on the FTO glass. Intriguingly, these TiO(2) flower clusters can then be exploited as photoanodes to produce DSSCs, yielding a power conversion efficiency of 2.94% despite their rutile nature, which is further increased to 4.07% upon the TiCl(4) treatment. PMID:23047462

Ye, Meidan; Liu, Hsiang-Yu; Lin, Changjian; Lin, Zhiqun

2013-01-28

156

Improved electron transfer and plasmonic effect in dye-sensitized solar cells with bi-functional Nb-doped TiO2/Ag ternary nanostructures.  

PubMed

TiO2 nanoparticles are surface-modified via atom transfer radical polymerization (ATRP) with a hydrophilic poly(oxyethylene)methacrylate (POEM), which can coordinate to the Ag precursor, i.e. silver trifluoromethanesulfonate (AgCF3SO3). Following the reduction of Ag ions, a Nb2O5 doping process and calcination at 450 °C, bi-functional Nb-doped TiO2/Ag ternary nanostructures are generated. The resulting nanostructures are characterized by energy-filtering transmission electron microscopy (EF-TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and UV-visible spectroscopy. The dye-sensitized solar cell (DSSC) based on the Nb-doped TiO2/Ag nanostructure photoanode with a polymerized ionic liquid (PIL) as the solid polymer electrolyte shows an overall energy conversion efficiency (?) of 6.9%, which is much higher than those of neat TiO2 (4.7%) and Nb-doped TiO2 (5.4%). The enhancement of ? is mostly due to the increase of current density, attributed to the improved electron transfer properties including electron injection, collection, and plasmonic effects without the negative effects of charge recombination or problems with corrosion. These properties are supported by intensity modulated photocurrent/voltage spectroscopy (IMPS/IMVS) and incident photon-to-electron conversion efficiency (IPCE) measurements. PMID:24457831

Park, Jung Tae; Chi, Won Seok; Jeon, Harim; Kim, Jong Hak

2014-03-01

157

Effects of tetrabutoxytitanium on photoelectrochemical properties of plastic-based TiO2 film electrodes for flexible dye-sensitized solar cells  

NASA Astrophysics Data System (ADS)

The flexible DSSCs based on conducting plastic substrates are fabricated using electrodes made of tetrabutoxytitanium (TBOT) mixed with P25 TiO2 nanoparticles at low temperature. To investigate the effects of TBOT on the flexible dye-sensitized solar cells, electrochemical impedance spectroscopy (EIS) is performed in the dark and under illumination conditions. Resistances for electron transport through TiO2, charge-transfer resistance related to the TiO2/redox electrolytes interface recombination, electron transport time and electron lifetime are quantified under different weight ratios of TBOT/P25. Additionally, the photovoltaic characteristics I-V curves and incident photon to current conversion efficiencies (IPCE) of flexible anodes made of different weight ratios of TBOT/P25 are obtained as well. It is found that the electrode under weight ratio 0.17 has the smallest inherent resistance, longest electron transport time and electron lifetime, lowest recombination rate and best performance with conversion efficiency 3.94%. These results indicate that after the weight ratios of TBOT/P25 is optimized, TBOT could enhance the interconnection between the TiO2 particles, improve the conductivity of the electrode and decrease the charge recombination. Above results demonstrate that adding TBOT to TiO2 is an easy and efficient method to improve the performance of the flexible DSSC fabricated at low temperature.

Fan, Ke; Peng, Tianyou; Chen, Junnian; Dai, Ke

2011-03-01

158

Preparation, photocatalytic activities, and dye-sensitized solar-cell performance of submicron-scale TiO2 hollow spheres.  

PubMed

We prepared submicron-scale spherical hollow particles of anatase TiO2 by using a polystyrene-bead template. The obtained particles were very uniform in size, with a diameter of 490 nm and a shell thickness of 30 nm. The Brunauer-Emmett-Teller surface area measurements revealed a large value of 70 m2/g. The photocatalytic property was investigated by the complete decomposition of gaseous isopropyl alcohol under UV irradiation. It was indicated that the activity of the hollow spheres was 1.8 times higher than that of the conventional P25 TiO2 nanoparticles with a diameter of 30 nm. Furthermore, we fabricated a dye-sensitized solar cell (DSC) using an electrode of the TiO2 hollow spheres, and examined the photovoltaic performance under simulated sunlight. Although the per-area efficiency was rather low (1.26%) because of a low area density of TiO2 on the electrode, the per-weight efficiency was 2.5 times higher than those of the conventional DSCs of TiO2. PMID:18088147

Kondo, Yoshihiko; Yoshikawa, Hirofumi; Awaga, Kunio; Murayama, Masaki; Mori, Tatsuo; Sunada, Kayano; Bandow, Shunji; Iijima, Sumio

2008-01-15

159

Formation and photovoltaic performance of few-layered graphene-decorated TiO2 nanocrystals used in dye-sensitized solar cells.  

PubMed

Few-layer graphene/TiO2 nanocrystal composites are successfully in situ synthesized at a low temperature of 400 °C using C28H16Br2 as the precursor. Raman mapping images show that the TiO2 nanocrystals are very uniformly dispersed in the composite films, and the in situ coating during the thermal decomposition process will favor the formation of a good interface combination between the few-layered graphene and the TiO2 nanocrystals. The few-layer graphene/TiO2 nanocrystal composites are used as photoanodes in dye-sensitized solar cells (DSSCs), and the conversion efficiency of 8.25% is obtained under full sun irradiation (AM 1.5), which increases by 65% compared with that of the pure TiO2 nanocrystal DSSCs (5.01%). It is found that the good interface combination between few-layered graphene and TiO2 nanocrystals may improve the electric conductivity and lifetime of photoinduced electrons in DSSCs. Moreover, some carbon atoms are doped into the crystal structure of the TiO2 nanocrystals during the thermal decomposition process, which will enhance the light absorption by narrowing the band gap and favor the improvement of the photovoltaic efficiency. PMID:24824192

Liu, Yueli; Cheng, Yuqing; Shu, Wei; Peng, Zhuoyin; Chen, Keqiang; Zhou, Jing; Chen, Wen; Zakharova, Galina S

2014-06-21

160

3-D solar cells by electrochemical-deposited Se layer as extremely-thin absorber and hole conducting layer on nanocrystalline TiO2 electrode  

PubMed Central

A three-dimensional selenium solar cell with the structure of Au/Se/porous TiO2/compact TiO2/fluorine-doped tin oxide-coated glass plates was fabricated by an electrochemical deposition method of selenium, which can work for the extremely thin light absorber and the hole-conducting layer. The effect of experimental conditions, such as HCl and H2SeO3 in an electrochemical solution and TiO2 particle size of porous layers, was optimized. This kind of solar cell did not use any buffer layer between an n-type electrode (porous TiO2) and a p-type absorber layer (selenium). The crystallinity of the selenium after annealing at 200°C for 3 min in the air was significantly improved. The cells with a selenium layer deposited at concentrations of HCl?=?11.5 mM and H2SeO3?=?20 mM showed the best performance, resulting in 1- to 2-nm thickness of the Se layer, short-circuit photocurrent density of 8.7 mA/cm2, open-circuit voltage of 0.65 V, fill factor of 0.53, and conversion efficiency of 3.0%. PMID:23286700

2013-01-01

161

Charge recombination reduction in dye-sensitized solar cells by means of an electron beam-deposited TiO 2 buffer layer between conductive glass and photoelectrode  

Microsoft Academic Search

A thin anatase titanium dioxide compact film was deposited by electron beam evaporation as buffer layer between the conductive transparent electrode and the porous TiO2-based photoelectrode in dye-sensitized solar cells. The effect of such a buffer layer on the back transfer reaction of electrons to tri-iodide ions in liquid electrolyte-based cells has been studied by means of both electrochemical impedance

Michele Manca; Francesco Malara; Luigi Martiradonna; Luisa De Marco; Roberto Giannuzzi; Roberto Cingolani; Giuseppe Gigli

2010-01-01

162

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

PubMed

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 ?m, whereas the thickness of the nanoparticle layer decreases from 4.3 to 2.8 ?m. 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 ?m 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. PMID:24354310

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

2014-01-01

163

Optical modeling-assisted characterization of dye-sensitized solar cells using TiO2 nanotube arrays as photoanodes  

PubMed Central

Summary Photovoltaic characteristics of dye-sensitized solar cells (DSSCs) using TiO2 nanotube (TNT) arrays as photoanodes were investigated. The TNT arrays were 3.3, 11.5, and 20.6 ?m long with the pore diameters of 50, 78.6, and 98.7 nm, respectively. The longest TNT array of 20.6 ?m in length showed enhanced photovoltaic performances of 3.87% with significantly increased photocurrent density of 8.26 mA·cm?2. This improvement is attributed to the increased amount of the adsorbed dyes and the improved electron transport property with an increase in TNT length. The initial charge generation rate was improved from 4 × 1021 s?1·cm?3 to 7 × 1021 s?1·cm?3 in DSSCs based on optical modelling analysis. The modelling analysis of optical processes inside TNT-based DSSCs using generalized transfer matrix method (GTMM) revealed that the amount of dye and TNT lengths were critical factors influencing the performance of DSSCs, which is consistent with the experimental results. PMID:24991527

Kim, Il Ku; Wang, Lianzhou; Amal, Rose

2014-01-01

164

Optical modeling-assisted characterization of dye-sensitized solar cells using TiO2 nanotube arrays as photoanodes.  

PubMed

Photovoltaic characteristics of dye-sensitized solar cells (DSSCs) using TiO2 nanotube (TNT) arrays as photoanodes were investigated. The TNT arrays were 3.3, 11.5, and 20.6 ?m long with the pore diameters of 50, 78.6, and 98.7 nm, respectively. The longest TNT array of 20.6 ?m in length showed enhanced photovoltaic performances of 3.87% with significantly increased photocurrent density of 8.26 mA·cm(-2). This improvement is attributed to the increased amount of the adsorbed dyes and the improved electron transport property with an increase in TNT length. The initial charge generation rate was improved from 4 × 10(21) s(-1)·cm(-3) to 7 × 10(21) s(-1)·cm(-3) in DSSCs based on optical modelling analysis. The modelling analysis of optical processes inside TNT-based DSSCs using generalized transfer matrix method (GTMM) revealed that the amount of dye and TNT lengths were critical factors influencing the performance of DSSCs, which is consistent with the experimental results. PMID:24991527

Yun, Jung-Ho; Kim, Il Ku; Ng, Yun Hau; Wang, Lianzhou; Amal, Rose

2014-01-01

165

Transfer and assembly of large area TiO2 nanotube arrays onto conductive glass for dye sensitized solar cells  

NASA Astrophysics Data System (ADS)

Highly ordered titanium oxide nanotube arrays are synthesized by a two-step anodic oxidation of pure titanium foil at constant voltage. It is found that the length of nanotube arrays firstly increased rapidly with the anodization time, and then the growth rate gradually slowed down with further increasing the anodization time. The mechanism of anodization time-dependent tube length growth is discussed. Large area free-standing TiO2 nanotube (TNT) arrays are detached from the underlying Ti foil and transferred onto the fluorine-doped tin oxide (FTO) conductive glass substrates to serve as the photoanodes of the dye-sensitized solar cells (DSSCs). The photoelectric performance of the DSSCs assembled by TNT/FTO films is strongly related to the tube length of titania and the surface treatment. For the photoanodes without any surface modification, the highest overall photovoltaic conversion efficiency (PCE) that can be achieved is 4.12% in the DSSC assembled with 33-?m-thick TNT arrays, while the overall PCE of DSSC based on the 33-?m-thick TNT arrays increases to 9.02% in response to the treatment with TiCl4.

Zhang, Jun; Li, Siqian; Ding, Hao; Li, Quantong; Wang, Baoyuan; Wang, Xina; Wang, Hao

2014-02-01

166

Influence of applied voltage on anodized TiO2 nanotube arrays and their performance on dye sensitized solar cells.  

PubMed

Highly ordered titanium dioxide (TiO2) nanotube films have been fabricated using anodic oxidation at different voltages (10 V to 70 V). The morphology, specific surface area, light absorbance capability and conductivity of the obtained films have been investigated. The anodized voltage was found to have a crucial influence on the morphology, light absorb capability and photo-electrochemical properties of the anodized nanotube films. The diameter of the nanotube increases linearly with the applied voltage. The nanotube film anodized at 30 V has the highest BET (Brunauer-Emmett-Teller) surface area, much more quantity of coated sensitizer N719, and the smallest resistance for dye sensitized solar cells (DSSC). Back side illuminated DSSC were assembled using these as-anodized nanotube films. Pt-FTO, which has a transmittance of about 50%, served as counter electrode. The best device based on nanotube films performed at 30 V gives a highest power conversion efficiency of 1.87%, with a photocurrent density (J(SC)) of 6.70 mA/cm2 and open circuit voltage (V(OC)) of 0.57 V. PMID:23862470

Wang, Hong; Li, Hongyi; Wang, Jinshu; Wu, Junshu; Liu, Man

2013-06-01

167

Theoretical study of charge recombination at the TiO2-electrolyte interface in dye sensitised solar cells  

NASA Astrophysics Data System (ADS)

The charge recombination reaction from the semiconductor (TiO2) conduction band to electron accepting electrolytes (I2, I2-, I3-) in dye-sensitised solar cells is investigated theoretically. The non-adiabatic theory of electron transfer has been adapted to compute the charge transfer rate measured in different experimental settings (namely with and without external illumination). In both cases we are able to provide an atomic level description of the charge recombination to the electrolyte (CRE), which is in good agreement with the experimental data available. The model employs a detailed density-functional theory (DFT) description of the semiconductor-electrolyte interface and the internal reorganization energy. A continuum dielectric model is used to evaluate the external component of the reorganization energy due to the solvent degrees of freedom. The intrinsic limitations of DFT are kept to a minimum by taking two key energetic parameters (the conduction band edge and the reaction energy) from the experiments. The proposed methodology correctly reproduces (i) the ratio between CRE rate to iodine and triiodide in dark, (ii) the absolute CRE rate to triiodide in dark, and (iii) the absolute CRE rate to I2- under illumination.

Maggio, E.; Martsinovich, N.; Troisi, A.

2012-12-01

168

High-efficiency dye-sensitized solar cells based on robust and both-end-open TiO2 nanotube membranes  

PubMed Central

In the present work, dye-sensitized solar cells (DSSCs) were fabricated by incorporating transparent electrodes of ordered free-standing TiO2 nanotube (TNT) arrays with both ends open transferred onto fluorine-doped tin oxide (FTO) conductive glass. The high-quality TiO2 membranes used here were obtained by a self-detaching technique, with the superiorities of facile but reliable procedures. Afterwards, these TNT membranes can be easily transferred to FTO glass substrates by TiO2 nanoparticle paste without any crack. Compared with those DSSCs consisting of the bottom-closed membranes or attached to Ti substrate, the carefully assembled and front-side illuminated DSSCs showed an enhanced solar energy conversion efficiency as high as 5.32% of 24-?m-thick TiO2 nanotube membranes without further treatments. These results reveal that by facilitating high-quality membrane synthesis, this kind of DSSCs assembly with optimized tube configuration can have a fascinating future. PMID:21794157

2011-01-01

169

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)

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.

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

2014-12-01

170

Ag2S quantum dots and N3 dye co-sensitized TiO2 nanotube arrays for a solar cell  

NASA Astrophysics Data System (ADS)

Ag2S quantum dots (QDs) and N3 dye co-sensitized TiO2 nanotube arrays (Ag2S-N3-TNAs) were prepared by the processes of anodization method followed by sequential chemical bath deposition (S-CBD) approach and dye sensitization, using FTO-based titanium film formed by vacuum ion coating method as a precursor. XRD, EDS, FE-SEM, TEM, UV-vis diffuse reflectance and photo electrochemical measurements were used to characterize the samples. Fabricated co-sensitized solar cell prototype exhibited a photocurrent density of 10.2 mA cm-2 and a power conversion efficiency of 4.40% based solar cells, which is higher than that of N3-sensitized TiO2 nanotube arrays (N3-TNAs) (8.5 mA cm-2 and 3.64%) under AM 1.5 light irradiation.

Ji, Gangqiang; Liu, Zhongqing; Guan, Debin; Yang, Yuntao

2013-10-01

171

Electron transport dynamics in TiO(2) films deposited on ti foils for back-illuminated dye-sensitized solar cells.  

PubMed

In this study, we examine the electron transport dynamics in TiO2 films of back-illuminated dye-sensitized solar cells. The TiO2 films are fabricated using electrophoretic deposition (EPD) and the conventional paste-coating (PC) of TiO2 nanoparticles on Ti-foil substrates. Intensity-modulated photocurrent spectroscopy reveals that red-light irradiation is more efficient than blue-light irradiation for generating photocurrents for back-illuminated cells. A single trapping-detrapping diffusion mode, without trap-free diffusion, reveals the electron transport dynamics involved in the backside illumination. The closely-packed EPD films exhibit a shorter electron transit time than does the loosely packed PC films. The porosity dependence of the electron diffusion rate is consistent with the 3D percolation model for metallic solid spheres. The EPD films possess longer electron lifetimes because of their smaller void fraction, which suppresses recombination with electrolytes. The EPD cells, which feature rapid electron transport and suppressed recombination in the TiO2 films, exhibit a maximum power conversion efficiency of 7.1%, which is higher than that of PC cells (6.0%). Because the distance between electron injection and collection is close to the film thickness and the transport lacks trap-free diffusion, the performance of back-illuminated cells is more sensitive to TiO2 film thickness and porosity than the performance of the front-illuminated cells. This study demonstrates the advantages of EPD-film architecture in promoting charge collection for high power conversion. PMID:24147618

Chen, Liang-Che; Hsieh, Chien-Te; Lee, Yuh-Lang; Teng, Hsisheng

2013-11-27

172

Solid-state organic\\/inorganic hybrid solar cells based on conjugated polymers and dye-sensitized TiO 2 electrodes  

Microsoft Academic Search

Several efforts on using a dye-sensitized TiO2 nanocrystalline solar cell (nc-DSC) by replacing the liquid electrolyte with a solid-state analogy (by either a polymer electrolyte or a hole conducting material) intend to eliminate practical problems with sealing and degradation. Polymeric materials that behave as hole conductors are of practical interest as replacements for the liquid electrolyte, since they are inexpensive

D. Gebeyehu; C. J. Brabec; N. S. Sariciftci

2002-01-01

173

Highly bendable composite photoelectrode prepared from TiO 2\\/polymer blend for low temperature fabricated dye-sensitized solar cells  

Microsoft Academic Search

We developed low temperature fabrication method for the bendable electrode, simply by blending of PMMA with TiO2, providing flexibility to the plastic dye-sensitized solar cells (DSSCs). Contrary to the conventional structure of photoelectrode, proposed electrode consists of elastic polymer and inorganic materials. It is expected that elastic polymer could absorb the external impact like bending, retarding the crack propagation into

Yuelong Li; Kicheon Yoo; Doh-Kwon Lee; Jong Hak Kim; Nam-Gyu Park; Kyungkon Kim; Min Jae Ko

2010-01-01

174

CdSe quantum dot-sensitized solar cell employing TiO2 nanotube working-electrode and Cu2S counter-electrode  

Microsoft Academic Search

We proposed a CdSe quantum dot (QD)-sensitized solar cell (QDSSC), which is constructed with a CdSe QD adsorbed TiO2 nanotube working electrode on a Ti substrate, a ring shaped Cu2S counter electrode, prepared on a brass substrate having a glass window, and polysulfide electrolyte. The light was incident from the counter electrode. An incident photon to current conversion efficiency as

Qing Shen; Akari Yamada; Satoru Tamura; Taro Toyoda

2010-01-01

175

Application of doped rare-earth oxide TiO2:(Tm3+, Yb3+) in dye-sensitized solar cells  

NASA Astrophysics Data System (ADS)

Tm3+ and Yb3+ are codoped into TiO2 film in a dye-sensitized solar cell (DSSC). The emission and excitation spectra of TiO2:(Tm3+, Yb3+) power shows that the rare-earth ions possess up-conversion luminescence function, which results in harvesting more incident light and increasing photocurrent for the DSSC. On the other hand, owing to the p-type doping effect by Tm3+ and Yb3+, the photovoltage of the DSSC is enhanced. Under a simulated solar light irradiation of 100 mW·cm-2, a DSSC containing Tm3+/Yb3+ achieves a conversion efficiency of 7.05 %, which is increased by 10.0% compared with a DSSC lacking Tm3+/Yb3+.

Xie, Guixiang; Wei, Yuelin; Fan, Leqing; Wu, Jihuai

2012-01-01

176

Effect of TiO2 nanoparticle-accumulated bilayer photoelectrode and condenser lens-assisted solar concentrator on light harvesting in dye-sensitized solar cells.  

PubMed

TiO2 nanoparticles (NPs) with a size of 240 nm (T240), used as a light-scattering layer, were applied on 25-nm-sized TiO2 NPs (T25) that were used as a dye-absorbing layer in the photoelectrodes of dye-sensitized solar cells (DSSCs). In addition, the incident light was concentrated via a condenser lens, and the effect of light concentration on the capacity of the light-scattering layer was systematically investigated. At the optimized focal length of the condenser lens, T25/T240 double layer (DL)-based DSSCs with the photoactive area of 0.36 cm2 were found to have the short circuit current (Isc) of 11.92 mA, the open circuit voltage (Voc) of 0.74 V, and power conversion efficiency (PCE) of approximately 4.11%, which is significantly improved when they were compared to the T25 single layer (SL)-based DSSCs without using a solar concentrator (the corresponding values were the Isc of 2.53 mA, the Voc of 0.69, and the PCE of 3.57%). Thus, the use of the optimized light harvesting structure in the photoelectrodes of DSSCs in conjunction with light concentration was found to significantly enhance the power output of DSSCs. PMID:23758633

Moon, Kook Joo; Lee, Sun Woo; Lee, Yong Hun; Kim, Ji Hoon; Ahn, Ji Young; Lee, Seung Jun; Lee, Deug Woo; Kim, Soo Hyung

2013-01-01

177

Effect of TiO2 nanoparticle-accumulated bilayer photoelectrode and condenser lens-assisted solar concentrator on light harvesting in dye-sensitized solar cells  

PubMed Central

TiO2 nanoparticles (NPs) with a size of 240 nm (T240), used as a light-scattering layer, were applied on 25-nm-sized TiO2 NPs (T25) that were used as a dye-absorbing layer in the photoelectrodes of dye-sensitized solar cells (DSSCs). In addition, the incident light was concentrated via a condenser lens, and the effect of light concentration on the capacity of the light-scattering layer was systematically investigated. At the optimized focal length of the condenser lens, T25/T240 double layer (DL)-based DSSCs with the photoactive area of 0.36 cm2 were found to have the short circuit current (Isc) of 11.92 mA, the open circuit voltage (Voc) of 0.74 V, and power conversion efficiency (PCE) of approximately 4.11%, which is significantly improved when they were compared to the T25 single layer (SL)-based DSSCs without using a solar concentrator (the corresponding values were the Isc of 2.53 mA, the Voc of 0.69, and the PCE of 3.57%). Thus, the use of the optimized light harvesting structure in the photoelectrodes of DSSCs in conjunction with light concentration was found to significantly enhance the power output of DSSCs. PMID:23758633

2013-01-01

178

Effect of TiO2 nanoparticle-accumulated bilayer photoelectrode and condenser lens-assisted solar concentrator on light harvesting in dye-sensitized solar cells  

NASA Astrophysics Data System (ADS)

TiO2 nanoparticles (NPs) with a size of 240 nm (T240), used as a light-scattering layer, were applied on 25-nm-sized TiO2 NPs (T25) that were used as a dye-absorbing layer in the photoelectrodes of dye-sensitized solar cells (DSSCs). In addition, the incident light was concentrated via a condenser lens, and the effect of light concentration on the capacity of the light-scattering layer was systematically investigated. At the optimized focal length of the condenser lens, T25/T240 double layer (DL)-based DSSCs with the photoactive area of 0.36 cm2 were found to have the short circuit current ( I sc) of 11.92 mA, the open circuit voltage ( V oc) of 0.74 V, and power conversion efficiency (PCE) of approximately 4.11%, which is significantly improved when they were compared to the T25 single layer (SL)-based DSSCs without using a solar concentrator (the corresponding values were the I sc of 2.53 mA, the V oc of 0.69, and the PCE of 3.57%). Thus, the use of the optimized light harvesting structure in the photoelectrodes of DSSCs in conjunction with light concentration was found to significantly enhance the power output of DSSCs.

Moon, Kook Joo; Lee, Sun Woo; Lee, Yong Hun; Kim, Ji Hoon; Ahn, Ji Young; Lee, Seung Jun; Lee, Deug Woo; Kim, Soo Hyung

2013-06-01

179

Open-ended TiO2 nanotubes formed by two-step anodization and their application in dye-sensitized solar cells  

NASA Astrophysics Data System (ADS)

We demonstrate a simple method to fabricate open-ended TiO2 nanotube (NT) based dye-sensitized solar cells (DSSCs), where the NTs are attached to either TiO2 nanorods (NRs) grown on fluorine-doped tin oxide (FTO) or FTO directly by nanoparticles (NPs). A completely hole-through TiO2 NT layer is fabricated via a two-step anodization with heat treatment immediately after the first anodization. DSSCs with the open-ended NTs show better photovoltaic performance than those with close-ended NTs, due to the enhanced charge transport in the open-ended structure. Under optimum conditions, DSSCs fabricated with the open-ended NT layer exhibit a short circuit current density (Jsc) of 19.10 mA cm-2, an open circuit voltage (Voc) of 0.68 V, a fill factor (FF) of 0.49, and a power conversion efficiency (eff) of 6.3%.We demonstrate a simple method to fabricate open-ended TiO2 nanotube (NT) based dye-sensitized solar cells (DSSCs), where the NTs are attached to either TiO2 nanorods (NRs) grown on fluorine-doped tin oxide (FTO) or FTO directly by nanoparticles (NPs). A completely hole-through TiO2 NT layer is fabricated via a two-step anodization with heat treatment immediately after the first anodization. DSSCs with the open-ended NTs show better photovoltaic performance than those with close-ended NTs, due to the enhanced charge transport in the open-ended structure. Under optimum conditions, DSSCs fabricated with the open-ended NT layer exhibit a short circuit current density (Jsc) of 19.10 mA cm-2, an open circuit voltage (Voc) of 0.68 V, a fill factor (FF) of 0.49, and a power conversion efficiency (eff) of 6.3%. Electronic supplementary information (ESI) available: Experimental details, XRD data of the samples with and without heat treatment, I-V characteristic DSSCs with different TiO2 NT lengths, and photovoltage decay of DSSCs under open circuit conditions. See DOI: 10.1039/c2nr11317a

Yip, Cho-Tung; Guo, Min; Huang, Haitao; Zhou, Limin; Wang, Yu; Huang, Chuanjun

2012-01-01

180

Dye-sensitized solar cells employing a SnO2-TiO2 core-shell structure made by atomic layer deposition.  

PubMed

This paper describes the synthesis and characterization of core-shell structures, based on SnO2 and TiO2, for use in dye-sensitized solar cells (DSC). Atomic layer deposition is employed to control and vary the thickness of the TiO2 shell. Increasing the TiO2 shell thickness to 2 nm improved the device performance of liquid electrolyte-based DSC from 0.7% to 3.5%. The increase in efficiency originates from a higher open-circuit potential and a higher short-circuit current, as well as from an improvement in the electron lifetime. SnO2-TiO2 core-shell DSC devices retain their photovoltage in darkness for longer than 500 seconds, demonstrating that the electrons are contained in the core material. Finally core-shell structures were used for solid-state DSC applications using the hole transporting material 2,2',7,7',-tetrakis(N, N-di-p-methoxyphenyl-amine)-9,9',-spirofluorene. Similar improvements in device performance were obtained for solid-state DSC devices. PMID:23574953

Karlsson, Martin; Jõgi, Indrek; Eriksson, Susanna K; Rensmo, Håkan; Boman, Mats; Boschloo, Gerrit; Hagfeldt, Anders

2013-01-01

181

Hydrothermal Growth and Application of ZnO Nanowire Films with ZnO and TiO2 Buffer Layers in Dye-Sensitized Solar Cells  

NASA Astrophysics Data System (ADS)

This paper reports the effects of the seed layers prepared by spin-coating and dip-coating methods on the morphology and density of ZnO nanowire arrays, thus on the performance of ZnO nanowire-based dye-sensitized solar cells (DSSCs). The nanowire films with the thick ZnO buffer layer (~0.8-1 ?m thick) can improve the open circuit voltage of the DSSCs through suppressing carrier recombination, however, and cause the decrease of dye loading absorbed on ZnO nanowires. In order to further investigate the effect of TiO2 buffer layer on the performance of ZnO nanowire-based DSSCs, compared with the ZnO nanowire-based DSSCs without a compact TiO2 buffer layer, the photovoltaic conversion efficiency and open circuit voltage of the ZnO DSSCs with the compact TiO2 layer (~50 nm thick) were improved by 3.9-12.5 and 2.4-41.7%, respectively. This can be attributed to the introduction of the compact TiO2 layer prepared by sputtering method, which effectively suppressed carrier recombination occurring across both the film-electrolyte interface and the substrate-electrolyte interface.

Yang, Weiguang; Wan, Farong; Chen, Siwei; Jiang, Chunhua

2009-12-01

182

All-solid-state hybrid solar cells based on a new organometal halide perovskite sensitizer and one-dimensional TiO2 nanowire arrays  

NASA Astrophysics Data System (ADS)

A novel organometal halide perovskite (CH3NH3PbI2Br) is synthesized and used as a visible light absorber to sensitize one-dimensional (1D) TiO2 nanowire arrays (NWAs) for all-solid-state hybrid solar cells. It achieved a power conversion efficiency (PCE) of 4.87% and an open circuit voltage (Voc) of 0.82 V, both higher than those of its analogue CH3NH3PbI3.A novel organometal halide perovskite (CH3NH3PbI2Br) is synthesized and used as a visible light absorber to sensitize one-dimensional (1D) TiO2 nanowire arrays (NWAs) for all-solid-state hybrid solar cells. It achieved a power conversion efficiency (PCE) of 4.87% and an open circuit voltage (Voc) of 0.82 V, both higher than those of its analogue CH3NH3PbI3. Electronic supplementary information (ESI) available: Experimental procedures, characterization details, including additional SEM, TEM, EDS, XRD and photovoltaic characteristics of cells based on TiO2 NWAs with different film thickness. See DOI: 10.1039/c3nr00218g

Qiu, Jianhang; Qiu, Yongcai; Yan, Keyou; Zhong, Min; Mu, Cheng; Yan, He; Yang, Shihe

2013-03-01

183

Explanation of Effect of Added Water on Dye-Sensitized Nanocrystalline TiO2 Solar Cell: Correlation between Performance and Carrier Relaxation Kinetics  

NASA Astrophysics Data System (ADS)

Time-resolved mid-IR transient absorption spectroscopy is employed to explore the mechanism of improving the performance of dye-sensitized TiO2 solar cell (DSSC) when a certain amount of H2O is added into the electrolyte. The relaxation kinetics of dye-sensitized TiO2 nanocrystalline film and the corresponding DSSC performance are investigated under different conditions. It is found that the interfacial charge recombination is retarded and electron injection efficiency is increased in the water vapour and in the electrolyte when D2O is added. The values of open-circuit photovoltage Voc and the short-circuit photocurrent Jsc of the cells are linearly correlated to the product of the two decay time constants. We also observed that Voc well correlates with electron injection efficiency. It provides a preliminary microscopic account for the function of the added water in improving the performance of DSSCs.

Zhao, Hui; Yin, Xiong; Li, Heng; Lin, Yuan; Weng, Yu-Xiang

2007-11-01

184

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

SciTech Connect

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.

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

2005-11-01

185

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

NASA Astrophysics Data System (ADS)

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.

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

186

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

PubMed

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

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

2012-10-01

187

Solar physical vapor deposition preparation and microstructural characterization of TiO2 based nanophases for dye-sensitized solar cell applications.  

PubMed

Titanium dioxide exists in three crystalline phases: anatase, rutile and brookite. Although rutile is thermodynamically more stable, anatase is considered as the most favorable phase for photocatalysis and solar energy conversion. Recent studies have shown a significant improvement of light harvesting and overall solar conversion efficiency of anatase nanoparticles in dye-sensitized solar cells (DSSCs) when using a mixture of anatase and rutile phases (10-15% rutile). TiO2 nanopowders have been prepared by a solar physical vapor deposition process (SPVD). This method has been developed in Odeillo-Font Romeu France using "heliotron" solar reactors working under concentrated sunlight in 2 kW solar furnaces. By controlling reactor's atmosphere type (air/argon) and gas pressure, several types of anatase/rutile nanophases have been obtained with slightly different microstructural properties and morphological characteristics. X-ray diffraction analyses (XRD) were performed on precursor and on the SPVD obtained nanopowders. Information concerning their phase composition and coherence diffraction domain (crystallites size and strain) was obtained. Nanopowders morphology has been studied by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). PMID:23421278

Negrea, Denis; Ducu, Catalin; Moga, Sorin; Malinovschi, Viorel; Monty, Claude J A; Vasile, Bogdan; Dorobantu, Dorel; Enachescu, Marian

2012-11-01

188

Coating effect of electrospun nanofibers of Nb-doped TiO2 mixed in photoelectrode of dye sensitized solar cells  

NASA Astrophysics Data System (ADS)

Electrospun nanofibers (NFs) of Nb doped TiO2 (TNO) were added as a conductive agent to TiO2 mesoporous layer in dye sensitized solar cells. In order to improve the mobility of carriers in NFs by reducing the barrier at grain boundaries among constituent nanoparticles in NFs, the surface of TNO-NFs was coated with a thin TNO layer by pulsed laser deposition with changing the deposition time td. It was found that the inter-grain space was filled first at td ? 5 min, and the diffusion velocity vD of carriers was increased by more than 10 times. Since Jsc showed an increase of ?15% while vD and the electron lifetime ?e decreased at td > 10 min, the carrier injection from dye/TiO2 nanoparticles to TNO-NFs was considered to be promoted.

Horie, Yuji; Deguchi, Makoto; Guo, Shirong; Aoki, Keisuke; Nomiyama, Teruaki

2014-01-01

189

Ga-doped ZnO transparent electrodes with TiO2 blocking layer/nanoparticles for dye-sensitized solar cells  

PubMed Central

Ga-doped ZnO [GZO] thin films were employed for the transparent electrodes in dye-sensitized solar cells [DSSCs]. The electrical property of the deposited GZO films was as good as that of commercially used fluorine-doped tin oxide [FTO]. In order to protect the GZO and enhance the photovoltaic properties, a TiO2 blocking layer was deposited on the GZO surface. Then, TiO2 nanoparticles were coated on the blocking layer, and dye was attached for the fabrication of DSSCs. The fabricated DSSCs with the GZO/TiO2 glasses showed an enhanced conversion efficiency of 4.02% compared to the devices with the normal GZO glasses (3.36%). Furthermore, they showed better characteristics even than those using the FTO glasses, which can be attributed to the reduced charge recombination and series resistance. PMID:22222148

2012-01-01

190

Hydrothermal growth of large-scale macroporous TiO2 nanowires and its application in 3D dye-sensitized solar cells  

NASA Astrophysics Data System (ADS)

Large-scale macroporous TiO2 nanowires (MTN) were directly grown on spiral-shaped titanium wires as photoanodes of dye-sensitized solar cells (DSSCs) via a facile hydrothermal reaction without any seeds, templates, and TiO2 powder. The MTN thin film was characterized by SEM, XRD and TEM. The studies revealed that the MTN thin film had better mechanical properties and provided an efficient pathway for the diffusion of liquid electrolyte. The efficiency of 0.86% for the 3D DSSC was obtained with a J sc of 2.30 mA/cm2, V oc of 616 mV, and FF of 0.61. This MNT-based mini 3D DSSC is a promising photovoltaic device for applications in the fields of high-integrated micro-electronic equipment.

Wang, Hai; Liu, Yong; Li, Ming; Huang, Hong; Zhong, Minyi; Shen, Hui

2009-10-01

191

Improving the performance of dye-sensitized solar cells with TiO2/graphene/TiO2 sandwich structure  

PubMed Central

This study investigates the extent to which the TiO2/graphene/TiO2 sandwich structure improves the performance of dye-sensitized solar cells (DSSCs) over that of DSSCs with the traditional structure. Studies have demonstrated that the TiO2/graphene/TiO2 sandwich structure effectively enhances the open circuit voltage (Voc), short-circuit current density (Jsc), and photoelectrical conversion efficiency (?) of DSSCs. The enhanced performance of DSSCs with the sandwich structure can be attributed to an increase in electron transport efficiency and in the absorption of light in the visible range. The DSSC with the sandwich structure in this study exhibited a Voc of 0.6 V, a high Jsc of 11.22 mA cm-2, a fill factor (FF) of 0.58, and a calculated ? of 3.93%, which is 60% higher than that of a DSSC with the traditional structure. PMID:25136284

2014-01-01

192

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

PubMed

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

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

2013-01-01

193

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

PubMed Central

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

2013-01-01

194

Enhanced performance of dye-sensitized solar cells based on TiO2 with NIR-absorption and visible upconversion luminescence  

NASA Astrophysics Data System (ADS)

TiO2 with NIR-absorption and visible upconversion luminescence (UC-TiO2) is prepared by a sol-gel method and calcined at 700 °C for 6 h. The material broadens the response region of dye sensitized solar cells (DSSCs) from an ultraviolet-visible region to the whole region of the solar spectrum. It shifts NIR sunlight to visible light which matches the strong absorbing region of the dye (N719). DSSCs based on UC-TiO2 achieved higher conversion efficiency than that on raw TiO2. UC-TiO2 was mixed with commercial raw TiO2 as additive, and the short-circuit current density, open-circuit voltage and conversion efficiency of the DSSC reached to the optimum values 13.38 mA/cm2, 0.78 V and 6.63% (AM1.5 global), comparing with the blank values: 7.99 mA/cm2, 0.75 V and 4.07%, respectively. Also the mechanisms of upconversion by multiphoton absorption and energy transfer processes are interpreted in this paper.

Liang, Li; Yulin, Yang; Mi, Zhou; Ruiqing, Fan; LeLe, Qiu; Xin, Wang; Lingyun, Zhang; Xuesong, Zhou; Jianglong, He

2013-02-01

195

1 Rectangular Bunched Rutile TiO2 Nanorod Arrays Grown on Carbon 2 Fiber for Dye-Sensitized Solar Cells  

E-print Network

1 Rectangular Bunched Rutile TiO2 Nanorod Arrays Grown on Carbon 2 Fiber for Dye-Sensitized Solar a study of rectangular bunched 13 TiO2 nanorod (NR) arrays grown on carbon fibers (CFs) 14 from titanium by a "dissolve and grow" method. After a 15 corrosion process in a strong acid solution, every single nano- 16

Wang, Zhong L.

196

Improved electron transfer and plasmonic effect in dye-sensitized solar cells with bi-functional Nb-doped TiO2/Ag ternary nanostructures  

NASA Astrophysics Data System (ADS)

TiO2 nanoparticles are surface-modified via atom transfer radical polymerization (ATRP) with a hydrophilic poly(oxyethylene)methacrylate (POEM), which can coordinate to the Ag precursor, i.e. silver trifluoromethanesulfonate (AgCF3SO3). Following the reduction of Ag ions, a Nb2O5 doping process and calcination at 450 °C, bi-functional Nb-doped TiO2/Ag ternary nanostructures are generated. The resulting nanostructures are characterized by energy-filtering transmission electron microscopy (EF-TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and UV-visible spectroscopy. The dye-sensitized solar cell (DSSC) based on the Nb-doped TiO2/Ag nanostructure photoanode with a polymerized ionic liquid (PIL) as the solid polymer electrolyte shows an overall energy conversion efficiency (?) of 6.9%, which is much higher than those of neat TiO2 (4.7%) and Nb-doped TiO2 (5.4%). The enhancement of ? is mostly due to the increase of current density, attributed to the improved electron transfer properties including electron injection, collection, and plasmonic effects without the negative effects of charge recombination or problems with corrosion. These properties are supported by intensity modulated photocurrent/voltage spectroscopy (IMPS/IMVS) and incident photon-to-electron conversion efficiency (IPCE) measurements.TiO2 nanoparticles are surface-modified via atom transfer radical polymerization (ATRP) with a hydrophilic poly(oxyethylene)methacrylate (POEM), which can coordinate to the Ag precursor, i.e. silver trifluoromethanesulfonate (AgCF3SO3). Following the reduction of Ag ions, a Nb2O5 doping process and calcination at 450 °C, bi-functional Nb-doped TiO2/Ag ternary nanostructures are generated. The resulting nanostructures are characterized by energy-filtering transmission electron microscopy (EF-TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and UV-visible spectroscopy. The dye-sensitized solar cell (DSSC) based on the Nb-doped TiO2/Ag nanostructure photoanode with a polymerized ionic liquid (PIL) as the solid polymer electrolyte shows an overall energy conversion efficiency (?) of 6.9%, which is much higher than those of neat TiO2 (4.7%) and Nb-doped TiO2 (5.4%). The enhancement of ? is mostly due to the increase of current density, attributed to the improved electron transfer properties including electron injection, collection, and plasmonic effects without the negative effects of charge recombination or problems with corrosion. These properties are supported by intensity modulated photocurrent/voltage spectroscopy (IMPS/IMVS) and incident photon-to-electron conversion efficiency (IPCE) measurements. Electronic supplementary information (ESI) available. See DOI: 10.1039/c3nr05652j

Park, Jung Tae; Chi, Won Seok; Jeon, Harim; Kim, Jong Hak

2014-02-01

197

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)

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.

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

2013-09-01

198

Photoelectrochemical performance of dye-sensitized solar cells based on the TiO2 nanotube array/nanoparticle-multilayer composite electrode  

NASA Astrophysics Data System (ADS)

Multilayer electrodes have been fabricated via a layer-by-layer process for application in the dye sensitized solar cells (DSSCs). The electrodes consist of the alternative layers of TiO2 nanoparticle (NP) film and nanotube (NT) array, of which the morphology and structure were well examined. Moreover, current density-voltage (J-V) curves and electrochemical impedance spectra were characterized after DSSC assembly for investigating the effect of layer numbers on electron transport performance. A conversion efficiency of 7.76% is demonstrated in the 3-layer DSSCs. Further, the dependence of the cell efficiency on the light harvesting and charge transport/recombination was discussed.

Song, D. M.; Qiang, Y. H.; Zhao, Y. L.; Gu, X. Q.; Song, C. B.

2013-07-01

199

Boron and sulfur co-doped TiO2 nanofilm as effective photoanode for high efficiency CdS quantum-dot-sensitized solar cells  

NASA Astrophysics Data System (ADS)

A modified polysulfide redox couple, (CH3)4N)2S/((CH3)4N)2Sn, was employed in CdS quantum dots (QDs) sensitized B/S co-doped TiO2 solar cell with NiS as counter electrode, followed by chemical bath deposition (CBD) in an organic solution to prepare the QDs-cell to ensure high wettability and superior penetration ability of the B/S co-doped TiO2 films, with the co-doping of B/S in TiO2, its band-gap was narrowed and significantly extended the light capture range, and an enhanced energy conversion efficiency of up to 3.6% was observed under AM 1.5 G illuminations, with a significantly high Voc of 1.217 V, a high ff of 88.2% and a short-circuit photocurrent (Jsc) of 3.35 mA cm-2.

Li, Ling; Yang, Xichuan; Zhang, Wenming; Zhang, Huayan; Li, Xiaowei

2014-12-01

200

Effects of Metal Oxide Modifications on Photoelectrochemical Properties of Mesoporous TiO2 Nanoparticles Electrodes for Dye-Sensitized Solar Cells  

NASA Astrophysics Data System (ADS)

Mesoporous TiO2 (m-TiO2) nanoparticles were used to prepare the porous film electrodes for dye-sensitized solar cells, and a second metal oxide (MgO, ZnO, Al2O3, or NiO) modification was carried out by dipping the m-TiO2 electrode into their respective nitrate solution followed by annealing at 500 °C. Experimental results indicated that the above second metal oxide modifications on m-TiO2 electrode are shown in all cases to act as barrier layer for the interfacial charge transfer processes, but film electron transport and interfacial charge recombination characteristics under applied bias voltage were dependent significantly on the existing states and kinds of these second metal oxides. Those changes based on second metal oxide modifications showed good correlation with the current-voltage analyses of dye-sensitized solar cell, and all modifications were found to increase the open-circuit photo-voltage in various degrees, while the MgO, ZnO, and NiO modifications result in 23%, 13%, and 6% improvement in cell conversion efficiency, respectively. The above observations indicate that controlling the charge transport and recombination is very important to improve the photovoltaic performance of TiO2-based solar cell.

Peng, Tian-you; Fan, Ke; Zhao, De; Yu, Li-juan; Li, Ren-jie

2012-10-01

201

High-performance inverted solar cells based on blend films of ZnO Naoparticles and TiO(2) nanorods as a cathode buffer layer.  

PubMed

We reported the favorable cathode buffer layer based on a blend of ZnO nanoparticles (NPs) and TiO2 nanorods (NRs) applied to inverted solar cells. In addition to the high optical transmittance, the resultant blend film gave a relatively dense film with lower roughness than that of the respective single-component film. This improved the interface contact between the buffer layer and photoactive layer and therefore reduced the contact resistance and leakage current. Moreover, the combination of NRs and NPs increased the efficiency of electron transport and collection by providing both a direct path for electron transport from TiO2 NRs and a large contact area between ZnO NPs and the active layer. Consequently, both the short-circuit current density (Jsc) and fill factor (FF) in the device were improved, leading to an improvement of the device performance. The best power conversion efficiency (PCE) based on the blend film as the buffer layer reached 8.82%, which was preferable to those of a single ZnO NP film (7.76%) and a TiO2 NR-based device (7.66%). PMID:24606632

Li, Pandeng; Sun, Chunming; Jiu, Tonggang; Wang, Guojie; Li, Jun; Li, Xiaofang; Fang, Junfeng

2014-03-26

202

Enhanced conversion efficiency in dye-sensitized solar cells based on bilayered nano-composite photoanode film consisting of TiO2 nanoparticles and nanofibers.  

PubMed

Novel TiO2 nanoparticles/nanofibers (NPs/NFs) bilayered nano-composite photoanode film for dye-sensitized solar cells (DSSCs) was fabricated through the combination of spin-coating and electrospinning. The NPs and NFs layers have complementary roles. The underlaid spin-coated NPs layer provides the photoanode film with higher specific surface area for dye adsorption and improved adhesion to conductive glass substrate. The overlaid electrospun NFs layer endows the photoanode film with better dye-loading and light-harvesting capabilities due to its porous meshwork structure. And the NFs layer also offers larger pore volume, which can facilitate the electrolyte diffusion and the activity regeneration of dye sensitizers. As a result, the electron transport is accelerated while the charge recombination is suppressed. Ascribing to the synergic effect of the NPs and NFs layers, the TiO2 NPs/NFs-based DSSCs achieve a conversion efficiency of 4.46%, which is nearly 14% higher than that of the pure TiO2 NPs-based ones. PMID:24738365

Du, P F; Song, L X; Xiong, J

2014-06-01

203

Mesoporous TiO2 aggregate photoanode with high specific surface area and strong light scattering for dye-sensitized solar cells  

NASA Astrophysics Data System (ADS)

Phase-pure anatase TiO2 nanocrystallite aggregates synthesized by a continuous supercritical fluid process have been first used for fabricating mesoporous photoanodes of dye-sensitized solar cells (DSCs). Due to the small size (11 nm) of the TiO2 nanocrystallites in the aggregates, the mesoporous photoanode provides a high specific surface area, 80 m2/g, which ensures high dye loading. At the same time, the submicrometer-sized aggregates endow the mesoporous photoanode with strong light scattering effect. Therefore, the light harvesting efficiency of the photoanode is increased. With an improved short-circuit current density, a high overall power conversion efficiency of 8.65% (100 mW/cm2, AM 1.5) is achieved without additional scattering layers, 12% enhanced compared with the DSCs fabricated from commercial Degussa P25 with exactly the same procedures. In addition, this supercritical fluid process is scalable and rapid (less than one minute) for TiO2 aggregates synthesis, which will push the commercialization of DSCs in the future.

Li, Chunhui; Luo, Yanhong; Guo, Xiaozhi; Li, Dongmei; Mi, Jianli; Sø, Lasse; Hald, Peter; Meng, Qingbo; Iversen, Bo B.

2012-12-01

204

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

NASA Astrophysics Data System (ADS)

Porous TiO2 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 TiO2 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, TiO2 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 (Mw) and 0.74% for high Mw polymer electrolytes.

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

2011-09-01

205

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

PubMed

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. PMID:21836328

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

2011-09-01

206

Open-ended TiO2 nanotubes formed by two-step anodization and their application in dye-sensitized solar cells.  

PubMed

We demonstrate a simple method to fabricate open-ended TiO(2) nanotube (NT) based dye-sensitized solar cells (DSSCs), where the NTs are attached to either TiO(2) nanorods (NRs) grown on fluorine-doped tin oxide (FTO) or FTO directly by nanoparticles (NPs). A completely hole-through TiO(2) NT layer is fabricated via a two-step anodization with heat treatment immediately after the first anodization. DSSCs with the open-ended NTs show better photovoltaic performance than those with close-ended NTs, due to the enhanced charge transport in the open-ended structure. Under optimum conditions, DSSCs fabricated with the open-ended NT layer exhibit a short circuit current density (J(sc)) of 19.10 mA cm(-2), an open circuit voltage (V(oc)) of 0.68 V, a fill factor (FF) of 0.49, and a power conversion efficiency (eff) of 6.3%. PMID:22159643

Yip, Cho-Tung; Guo, Min; Huang, Haitao; Zhou, Limin; Wang, Yu; Huang, Chuanjun

2012-01-21

207

Layer-by-layer formation of block-copolymer-derived TiO(2) for solid-state dye-sensitized solar cells.  

PubMed

Morphology control on the 10 nm length scale in mesoporous TiO(2) films is crucial for the manufacture of high-performance dye-sensitized solar cells. While the combination of block-copolymer self-assembly with sol-gel chemistry yields good results for very thin films, the shrinkage during the film manufacture typically prevents the build-up of sufficiently thick layers to enable optimum solar cell operation. Here, a study on the temporal evolution of block-copolymer-directed mesoporous TiO(2) films during annealing and calcination is presented. The in-situ investigation of the shrinkage process enables the establishment of a simple and fast protocol for the fabrication of thicker films. When used as photoanodes in solid-state dye-sensitized solar cells, the mesoporous networks exhibit significantly enhanced transport and collection rates compared to the state-of-the-art nanoparticle-based devices. As a consequence of the increased film thickness, power conversion efficiencies above 4% are reached. PMID:22174177

Guldin, Stefan; Docampo, Pablo; Stefik, Morgan; Kamita, Gen; Wiesner, Ulrich; Snaith, Henry J; Steiner, Ullrich

2012-02-01

208

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

PubMed

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 ?Ah under the discharge density of 100 ?A. 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. PMID:22519631

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

2012-05-01

209

All-solid-state hybrid solar cells based on a new organometal halide perovskite sensitizer and one-dimensional TiO2 nanowire arrays.  

PubMed

A novel organometal halide perovskite (CH3NH3PbI2Br) is synthesized and used as a visible light absorber to sensitize one-dimensional (1D) TiO2 nanowire arrays (NWAs) for all-solid-state hybrid solar cells. It achieved a power conversion efficiency (PCE) of 4.87% and an open circuit voltage (Voc) of 0.82 V, both higher than those of its analogue CH3NH3PbI3. PMID:23508213

Qiu, Jianhang; Qiu, Yongcai; Yan, Keyou; Zhong, Min; Mu, Cheng; Yan, He; Yang, Shihe

2013-04-21

210

CdSe quantum dot-sensitized solar cell employing TiO2 nanotube working-electrode and Cu2S counter-electrode  

NASA Astrophysics Data System (ADS)

We proposed a CdSe quantum dot (QD)-sensitized solar cell (QDSSC), which is constructed with a CdSe QD adsorbed TiO2 nanotube working electrode on a Ti substrate, a ring shaped Cu2S counter electrode, prepared on a brass substrate having a glass window, and polysulfide electrolyte. The light was incident from the counter electrode. An incident photon to current conversion efficiency as high as 65% and a photovoltaic conversion efficiency as high as 1.8% under one sun have been achieved. We have demonstrated less costly QDSSC, without the requirement for both a transparent conductive electrode or a platinum film.

Shen, Qing; Yamada, Akari; Tamura, Satoru; Toyoda, Taro

2010-09-01

211

Characterization of N, N?-bis-2-(1-hydoxy-4-methylpentyl)-3, 4, 9, 10-perylene bis (dicarboximide) sensitized nanocrystalline TiO 2 solar cells with polythiophene hole conductors  

Microsoft Academic Search

We have fabricated solid-state, dye-sensitized nanocrystalline TiO2 solar cells (DSSC) based on perylene derivative dye, N,N?-bis-2-(1-hydoxy-4-methylpentyl)-3,4,9,10-perylene bis (dicarboximide) (HMPER) with two different polythiophenes as hole conductors; i.e. poly (3-octyl thiophene) (P3OT) and poly (3-hexyl thiophene) (P3HT), respectively. HMPER adsorbs strongly to the surface of nanocrystalline TiO2 and inject electrons into TiO2 conduction band upon absorption of light. Polythiophene derivatives are

Ceylan Zafer; Canan Karapire; N. Serdar Sariciftci; Siddik Icli

2005-01-01

212

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

NASA Astrophysics Data System (ADS)

Hierarchical TiO2 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 m2 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%).

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

2012-12-01

213

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

PubMed

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

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

2013-01-01

214

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

PubMed

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 ?A cm(-2) at 1.23 V versus the reversible hydrogen electrode, compared with 28.3 ?A 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

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

2013-07-22

215

Anatase TiO2 beads having ultra-fast electron diffusion rates for use in low temperature flexible dye-sensitized solar cells  

NASA Astrophysics Data System (ADS)

The first use of mesoporous TiO2 beads in plastic substrate flexible dye-sensitized solar cell (FDSC) is demonstrated. Pure anatase TiO2 beads with various sizes (250-750 nm) and characteristics are obtained using a modified and efficient two-step method. The concept of chemical sintering, eliminating the step of additive removal, is used to prepare bead-containing paste for room temperature fabrication of photoanode having good adhesion to the substrate. The obtained photoanodes are examined for their dye loadings and light absorbance properties. Various plastic substrate FDSCs having commercial P25- and bead-containing photoanodes are fabricated and evaluated. The resulting cells are evaluated for the J-V characteristics, electron diffusion time, electron lifetime, charge-collection efficiency, electron-injection efficiency and incident photon-to-electron conversion efficiency. The bead-only cells not only have better efficiencies, as high as ?5%, but also exhibit ultra-fast electron diffusion rates, less than 1 ms (?0.37 ms, 7.6 ?m). The best efficiency and electron diffusion rates are respectively 15% higher and two-order of magnitude faster than the P25-only cell. The effects of the bead characteristics on the cell performance is presented and discussed.

Ke, Chun-Ren; Ting, Jyh-Ming

2012-06-01

216

A strategy to reduce the angular dependence of a dye-sensitized solar cell by coupling to a TiO2 nanotube photonic crystal.  

PubMed

Almost all types of solar cells suffer from a decreased power output when the incident light is tilted away from normal since the incident intensity generally follows a cosine law of the incident angle. Making use of the blue shift nature of the Bragg position of a TiO2 nanotube photonic crystal (NT PC) under oblique incidence, we demonstrate experimentally that the use of the NT PC can partially compensate the cosine power loss of a dye-sensitized solar cell (DSSC). The strategy used here is to purposely choose the Bragg position of the NT PC to be at the longer wavelength side of the dye absorption peak. When the incident light is tilted, the blue shift of the Bragg position results in more overlap with the dye absorption peak, generating a higher efficiency that partially compensates the reduced photon flux due to light inclination. Moreover, the unique structure of the vertically aligned TiO2 nanotubes contributes an additional scattering effect when the incident light is tilted. As a result, the power output of a DSSC coupled with the NT PC layer shows a much flatter angular dependence than a DSSC without the NT PC. At all the incident angles, the DSSC coupled with the NT PC layer also shows a higher power conversion efficiency than the one without. The concept of using NT PC to mitigate the angular dependence of DSSCs can be easily extended to many other optoelectronic devices that are irradiance sensitive. PMID:25247717

Guo, Min; Xie, Keyu; Liu, Xiaolin; Wang, Yu; Zhou, Limin; Huang, Haitao

2014-10-01

217

The action mechanism of TiO2:NaYF4:Yb3+,Tm3+ cathode buffer layer in highly efficient inverted organic solar cells  

NASA Astrophysics Data System (ADS)

We report the fabrication and characteristics of organic solar cells with 6.86% power conversion efficiency (PCE) by doping NaYF4:Yb3+,Tm3+ into TiO2 cathode buffer layer. The dependence of devices performance on doping concentration of NaYF4:Yb3+,Tm3+ is investigated. Results indicate that short-circuit current density (Jsc) has an apparent improvement, leading to an enhancement of 22.7% in PCE for the optimized doping concentration of 0.05 mmol ml-1 compared to the control devices. NaYF4:Yb3+,Tm3+ nanoparticles (NPs) can play threefold roles, one is that the incident light in visible region can be scattered by NaYF4 NPs, the second is that solar irradiation in infrared region can be better utilized by Up-conversion effect of Yb3+ and Tm3+ ions, the third is that electron transport property in TiO2 thin film can be greatly improved.

Liu, Chunyu; Chen, Huan; Zhao, Dan; Shen, Liang; He, Yeyuan; Guo, Wenbin; Chen, Weiyou

2014-08-01

218

Charge transport improvement employing TiO2 nanotube arrays as front-side illuminated dye-sensitized solar cell photoanodes.  

PubMed

TiO(2) nanotube (NT) arrays with different lengths were fabricated by anodic oxidation of Ti foil and free-standing NT membranes were detached by the metal substrate and bonded on the fluorine-doped tin oxide surface implementing an easy procedure. Morphology of the as-grown material and of the prepared photoanode was investigated by means of electron microscopy, deepening the investigation on the thermal treatment effect. Crystalline orientation and exposed surface area were studied by X-ray diffraction and Brunauer-Emmett-Teller measurements, showing suitable characteristics for the application in dye-sensitized solar cells (DSCs). DSCs were assembled employing a microfluidic housing system. The cell performances and the electron transport properties as a function of the tube length, before and after a TiCl(4) treatment, were characterized by I-V electrical measurements, incident photon-to-electron conversion efficiency, electrochemical impedance spectroscopy and open circuit voltage decay. Fitting the impedance spectra with an equivalent circuit, it was possible to obtain information on the electron diffusion properties into the TiO(2) nanotubes. A comparison with the charge transport properties evaluated in nanoparticle-based photoanodes witnesses a noteworthy increase of electron lifetime and diffusion length, yielding an overall power conversion efficiency up to 7.56%. PMID:22918400

Lamberti, Andrea; Sacco, Adriano; Bianco, Stefano; Manfredi, Diego; Cappelluti, Federica; Hernandez, Simelys; Quaglio, Marzia; Pirri, Candido Fabrizio

2013-02-21

219

Alignment of the dye's molecular levels with the TiO(2) band edges in dye-sensitized solar cells: a DFT-TDDFT study.  

PubMed

We present a theoretical study of the lineup of the LUMO of Ru(II)-polypyridyl (N3 and N719) molecular dyes with the conduction band edge of a TiO(2) anatase nanoparticle. We use density functional theory (DFT) and the Car-Parrinello scheme for efficient optimization of the dye-nanoparticle systems, followed by hybrid B3LYP functional calculations of the electronic structure and time-dependent DFT (TDDFT) determination of the lowest vertical excitation energies. The electronic structure and TDDFT calculations are performed in water solution, using a continuum model. Various approximate procedures to compute the excited state oxidation potential of dye sensitizers are discussed. Our calculations show that the level alignment for the interacting nanoparticle-sensitizer system is very similar, within about 0.1 eV, to that for the separated TiO(2) and dye. The excellent agreement of our results with available experimental data indicates that the approach of this work could be used as an efficient predictive tool to help the optimization of dye-sensitized solar cells. PMID:21832662

De Angelis, Filippo; Fantacci, Simona; Selloni, Annabella

2008-10-22

220

In-situ synthesis of TiO2 network nanoporous structure on Ti wire substrate and its application in fiber dye sensitized solar cells  

NASA Astrophysics Data System (ADS)

In this paper, we explore a two-step treatment method to modify the Ti wires which are used as anode substrates of fiber dye sensitized solar cells (FDSSCs). A special kind of network nanoporous structure is formed on the surface of Ti wire substrates through sodium hydroxide hydrothermal reaction and titanium tetrachloride (TiCl4) assistant treatment. Nanoporous structures with different sizes are in-situ grown on the Ti wire substrates by changing the hydrothermal reaction condition. Then, TiO2 network nanoporous structures with branch-like nano-structure or 2D nanoflakes are obtained after TiCl4 treatment. The effects of these network nanoporous structures on the FDSSC performances are investigated intensively. It is found that these special network nanoporous structures between TiO2 nanoparticle active layer and Ti wire substrate are beneficial to the connection of the nanoparticle layer and fiber-shaped substrate, thus improving the electron transport rate and prolonging electron lifetime. As a result, the power conversion efficiency of this parallel assembled FDSSC increases to 4.64% from 2.56% after this two-step treatment.

Tao, Hong; Fang, Guo-jia; Ke, Wei-jun; Zeng, Wei; Wang, Jing

2014-01-01

221

Morphology transformations in tetrabutyl titanate-acetic acid system and sub-micron/micron hierarchical TiO2 for dye-sensitized solar cells  

NASA Astrophysics Data System (ADS)

The concentration of tetrabutyl titanate (TBT) and H2O influence on the reaction kinetics of TBT and acetic acid (AcOH) solvothermal system are systematically studied. It is found that TBT and H2O have greatly accelerated the hydrolysis-condensation process of the TBT-AcOH system. By adjusting those concentrations with reaction time, we prepare five kinds of sub-micron/micron precursors, which are hierarchical structures consisting of different primary building blocks. The morphology of these precursors varies from noninterlaced structures composed of flower-like microsphere and ellipsoid sphere to interlaced structures composed of flower-like microsphere interlaced nanofibers, ellipsoid spheres interlaced flower-like microsphere and nanoparticles interlaced flower-like microsphere. These interlaced structures are synthesized for the first time and are not ordinary mixtures of the noninterlaced structures. After heat treatment, these precursors are transformed to anatase TiO2. Shape-dependent photovoltaic performances of dye-sensitized solar cells (DSSCs) are also discussed. DSSCs based on these hierarchical sub-micron/micron TiO2 show 7.3%-7.9% energy conversion efficiencies, and the devices based on interlaced structures have higher efficiencies (7.4%-7.9%) than those of the devices based on noninterlaced structures (7.3%-7.6%).

Huang, Niu; Xie, Yanan; Sebo, Bobby; Liu, Yumin; Sun, Xiaohua; Peng, Tao; Sun, Weiwei; Bu, Chenghao; Guo, Shishang; Zhao, Xingzhong

2013-11-01

222

TiO2 nanorods: a facile size- and shape-tunable synthesis and effective improvement of charge collection kinetics for dye-sensitized solar cells.  

PubMed

In this paper, we present a novel, high-yield, and cost-effective hydrothermal method for the preparation of single crystal-like anatase TiO2 nanorods (NRs) with specific {101} exposed crystal planes and preferred [001] growth direction, which is governed by the "oriented attachment" mechanism. The successful synthesis of TiO2 NRs and fine tuning on their size and shape could be easily accomplished by adjusting the solvent compositions. The salient feature of these NRs, in lieu of traditional nanoparticles as building blocks of photoanodes in dye-sensitized solar cell (DSSC) system, rests with their significantly reduced grain boundaries. The electron diffusion and recombination kinetics have been critically compared for the first time with respect to the size and shape of the novel building blocks. A high efficiency of 8.87% has finally been achieved for DSSC based on long-thin NRs rather than short-thin or long-thick NRs, which possesses balanced optimizations on charge collection and light-harvesting properties. PMID:24833257

Zhang, Wenjun; Xie, Yan; Xiong, Dehua; Zeng, Xianwei; Li, Zhihong; Wang, Mingkui; Cheng, Yi-Bing; Chen, Wei; Yan, Keyou; Yang, Shihe

2014-06-25

223

3D Hierarchical Rutile TiO2 and Metal-free Organic Sensitizer Producing Dye-sensitized Solar Cells 8.6% Conversion Efficiency  

NASA Astrophysics Data System (ADS)

Three-dimensional (3D) hierarchical nanoscale architectures comprised of building blocks, with specifically engineered morphologies, are expected to play important roles in the fabrication of `next generation' microelectronic and optoelectronic devices due to their high surface-to-volume ratio as well as opto-electronic properties. Herein, a series of well-defined 3D hierarchical rutile TiO2 architectures (HRT) were successfully prepared using a facile hydrothermal method without any surfactant or template, simply by changing the concentration of hydrochloric acid used in the synthesis. The production of these materials provides, to the best of our knowledge, the first identified example of a ledgewise growth mechanism in a rutile TiO2 structure. Also for the first time, a Dye-sensitized Solar Cell (DSC) combining a HRT is reported in conjunction with a high-extinction-coefficient metal-free organic sensitizer (D149), achieving a conversion efficiency of 5.5%, which is superior to ones employing P25 (4.5%), comparable to state-of-the-art commercial transparent titania anatase paste (5.8%). Further to this, an overall conversion efficiency 8.6% was achieved when HRT was used as the light scattering layer, a considerable improvement over the commercial transparent/reflector titania anatase paste (7.6%), a significantly smaller gap in performance than has been seen previously.

Lin, Jianjian; Heo, Yoon-Uk; Nattestad, Andrew; Sun, Ziqi; Wang, Lianzhou; Kim, Jung Ho; Dou, Shi Xue

2014-08-01

224

Nanoclay gelation approach toward improved dye-sensitized solar cell efficiencies: an investigation of charge transport and shift in the TiO2 conduction band.  

PubMed

Nanoclay minerals play a promising role as additives in the liquid electrolyte to form a gel electrolyte for quasi-solid-state dye-sensitized solar cells, because of the high chemical stability, unique swelling capability, ion exchange capacity, and rheological properties of nanoclays. Here, we report the improved performance of a quasi-solid-state gel electrolyte that is made from a liquid electrolyte and synthetic nitrate-hydrotalcite nanoclay. Charge transport mechanisms in the gel electrolyte and nanoclay interactions with TiO(2)/electrolyte interface are discussed in detail. The electrochemical analysis reveals that the charge transport is solely based on physical diffusion at the ratio of [PMII]:[I(2)] = 10:1 (where PMII is 1-propyl-3-methylimidazolium iodide). The calculated physical diffusion coefficient shows that the diffusion of redox ions is not affected much by the viscosity of nanoclay gel. The addition of nitrate-hydrotalcite clay in the electrolyte has the effect of buffering the protonation process at the TiO(2)/electrolyte interface, resulting in an upward shift in the conduction band and a boost in open-circuit voltage (V(OC)). Higher V(OC) values with undiminished photocurrent is achieved with nitrate-hydrotalcite nanoclay gel electrolyte for organic as well as for inorganic dye (D35 and N719) systems. The efficiency for hydrotalcite clay gel electrolyte solar cells is increased by 10%, compared to that of the liquid electrolyte. The power conversion efficiency can reach 10.1% under 0.25 sun and 9.6% under full sun. This study demonstrates that nitrate-hydrotalcite nanoclay in the electrolyte not only solidifies the liquid electrolyte to prevent solvent leakage, but also facilitates the improvement in cell efficiency. PMID:23252392

Wang, Xiu; Kulkarni, Sneha A; Ito, Bruno Ieiri; Batabyal, Sudip K; Nonomura, Kazuteru; Wong, Chee Cheong; Grätzel, Michael; Mhaisalkar, Subodh G; Uchida, Satoshi

2013-01-23

225

A strategy to reduce the angular dependence of a dye-sensitized solar cell by coupling to a TiO2 nanotube photonic crystal  

NASA Astrophysics Data System (ADS)

Almost all types of solar cells suffer from a decreased power output when the incident light is tilted away from normal since the incident intensity generally follows a cosine law of the incident angle. Making use of the blue shift nature of the Bragg position of a TiO2 nanotube photonic crystal (NT PC) under oblique incidence, we demonstrate experimentally that the use of the NT PC can partially compensate the cosine power loss of a dye-sensitized solar cell (DSSC). The strategy used here is to purposely choose the Bragg position of the NT PC to be at the longer wavelength side of the dye absorption peak. When the incident light is tilted, the blue shift of the Bragg position results in more overlap with the dye absorption peak, generating a higher efficiency that partially compensates the reduced photon flux due to light inclination. Moreover, the unique structure of the vertically aligned TiO2 nanotubes contributes an additional scattering effect when the incident light is tilted. As a result, the power output of a DSSC coupled with the NT PC layer shows a much flatter angular dependence than a DSSC without the NT PC. At all the incident angles, the DSSC coupled with the NT PC layer also shows a higher power conversion efficiency than the one without. The concept of using NT PC to mitigate the angular dependence of DSSCs can be easily extended to many other optoelectronic devices that are irradiance sensitive.Almost all types of solar cells suffer from a decreased power output when the incident light is tilted away from normal since the incident intensity generally follows a cosine law of the incident angle. Making use of the blue shift nature of the Bragg position of a TiO2 nanotube photonic crystal (NT PC) under oblique incidence, we demonstrate experimentally that the use of the NT PC can partially compensate the cosine power loss of a dye-sensitized solar cell (DSSC). The strategy used here is to purposely choose the Bragg position of the NT PC to be at the longer wavelength side of the dye absorption peak. When the incident light is tilted, the blue shift of the Bragg position results in more overlap with the dye absorption peak, generating a higher efficiency that partially compensates the reduced photon flux due to light inclination. Moreover, the unique structure of the vertically aligned TiO2 nanotubes contributes an additional scattering effect when the incident light is tilted. As a result, the power output of a DSSC coupled with the NT PC layer shows a much flatter angular dependence than a DSSC without the NT PC. At all the incident angles, the DSSC coupled with the NT PC layer also shows a higher power conversion efficiency than the one without. The concept of using NT PC to mitigate the angular dependence of DSSCs can be easily extended to many other optoelectronic devices that are irradiance sensitive. Electronic supplementary information (ESI) available. See DOI: 10.1039/c4nr03712j

Guo, Min; Xie, Keyu; Liu, Xiaolin; Wang, Yu; Zhou, Limin; Huang, Haitao

2014-10-01

226

Photocatalytic and Dye-Sensitized Solar Cell Performances of {010}-Faceted and [111]-Faceted Anatase TiO2 Nanocrystals Synthesized from Tetratitanate Nanoribbons.  

PubMed

The morphology and exposed facet of the anatase-type TiO2 are very important to improve the photocatalytic activity and photovoltaic performance in dye-sensitized solar cells. In this work, we report the synthesis and the photocatalytic and dye-sensitized solar cell performances of anatase-type TiO2 single nanocrystals with exposed {010}- and [111]-facets and with various morphologies by using exfoliated tetratitanate nanoribbons as precursors. The precursor nanoribbons were prepared from the exfoliation of the protonated and, subsequently, tetramethylammonium/H(+) ion-exchanged K2Ti4O9. The colloidal suspension containing the nanoribbons was hydrothermally heated with a microwave-assistance at temperatures from 120 to 190 °C after pH was adjusted to 0.5-14. The dependence of the crystalline phases on temperature and pH indicated that anatase single phase can be obtained at pH 3-13 whereas temperatures higher than 160 °C. The [111]-faceted nanorod-shaped anatase nanocrystals were formed preferentially at pH ? 3, whereas the {010}-faceted anatase nanocrystals with morphologies of rhombic, cuboid, and spindle were preferentially at pH ?5. The morphology observation revealed that the nanoribbons were transformed to anatase nanocrystals mainly by the topotactic structural transformation reaction accompanied by an Ostwald ripening reaction, and pH of the reaction solution took a critical role in the crystal morphology change. At pH ?1, the mixture of anatase, rutile, and brookite were obtained at higher temperature conditions. The photocatalytic activity and photovoltaic performance were enhanced in an order of surface without a specific facet < [111]-faceted surface < {010}-faceted surface. PMID:25158319

Du, Yi-En; Feng, Qi; Chen, Changdong; Tanaka, Yasuhiro; Yang, Xiaojing

2014-09-24

227

Improved performance of dye-sensitized solar cells: An TiO2-nano-SiO2 hybrid photoanode with post-treatment of TiCl4 aqueous solution  

NASA Astrophysics Data System (ADS)

A TiO2-nano-SiO2 hybrid film was prepared on a conductive F-doped tin oxide (FTO) substrate by depositing a mixture paste of TiO2 (P25) and nano-sized SiO2 particles. The hybrid film was further treated by a titanium tetrachloride (TiCl4) aqueous solution with different concentrations before it was assembled as a photoanode in dye sensitized solar cells (DSSCs). We studied the performance of DSSCs by using the dye molecule of cis-bis(isothiocy-anato)-bis-(2,2'-bipyridyl-4,4'-dicarboxylato)-ruthenium(II) bis-tetrabutylammonium (N719) as sensitizer. Results suggested that the post-treatment using TiCl4 could enhance the dye adsorption. The thin TiO2 layer hydrolyzed from TiCl4 could fill gaps between nanoparticles in the composite film, leading to a better electron transport than non-treated films, and improve the light harvesting efficiency. The optimal concentration was found to be 75 mM for the post-treatment of TiO2-SiO2 hybrid film by TiCl4 solution. A photoelectron conversion efficiency of 6.39% was achieved in the back-side illuminated dye-sensitized solar cells, which is ˜105% higher than the basic efficiency of the bare TiO2 sensitized sample. TiO2-nano-SiO2 hybrid photoanode was prepared by incorporation of nano-sized SiO2 in the TiO2 film. The introduced SiO2 as a wide band-gap material gives a significant improvement of the performance of corresponding DSSCs in terms of photocurrent densities and energy conversion efficiency.

Liu, Ling; Niu, Haihong; Zhang, Shouwei; Wan, Lei; Miao, Shiding; Xu, Jinzhang

2012-11-01

228

Hierarchically Structured Microspheres for High-Efficiency Rutile TiO2Based Dye-Sensitized Solar Cells  

E-print Network

candidate for use in water splitting, photo- catalysis, sensors, and dye-sensitized solar cells (DSSCs) over, nanowires, nanosheets, nano- spheres, etc., have been obtained by many synthetic approaches, including sol-gel anodization.18-26 Among these techniques, low temperature and atmospheric pressure synthetic strategies

Lin, Zhiqun

229

A novel UV-mediated low-temperature sintering of TiO 2 for dye-sensitized solar cells  

Microsoft Academic Search

Titania pastes were fired at 450°C in oxygen to give white titania that was used to prepare dye-sensitized solar cells (DSSC). Titania fired at lower temperature and\\/or under inert atmosphere have brown stripes and cells made from these stripes had no measurable efficiency. When the titania paste was screen printed and then heated and simultaneously irradiated with UV light, white

Larry N. Lewis; James L. Spivack; Shellie Gasaway; Eric D. Williams; John Y. Gui; Venkatesan Manivannan; Oltea P. Siclovan

2006-01-01

230

High performance PbS quantum dot sensitized solar cells via electric field assisted in situ chemical deposition on modulated TiO2 nanotube arrays.  

PubMed

Quantum dot sensitized solar cells (QDSSCs) are attractive photovoltaic devices due to their simplicity and low material requirements. However, efforts to realize high efficiencies in QDSSCs have often been offset by complicated processes and expensive or toxic materials, significantly limiting their useful application. In this work, we have realized for the first time, high performance PbS QDSSCs based on TiO2 nanotube arrays (NTAs) via an in situ chemical deposition method controlled by a low electric field. An efficiency, ?, of ~3.41% under full sun illumination has been achieved, which is 133.6% higher than the best result previously reported for a simple system without doping or co-sensitizing, and comparable to systems with additional chemicals. Furthermore, a high open-circuit voltage (0.64 V), short-circuit current (8.48 mA cm(-2)) and fill factor (0.63) have been achieved. A great increase in the quantity of the loaded quantum dots (QDs) in the NTAs was obtained from the in situ electric field assisted chemical bath deposition (EACBD) process, which was the most significant contributing factor with respect to the high JSC. The high VOC and FF have been attributed to a much shorter electron path, less structural and electronic defects, and lower recombination in the ordered TiO2 NTAs produced by oscillating anodic voltage. Besides, the optimal film thickness (~4 ?m) based on the NTAs was much thinner than that of the control cell based on nanoporous film (~30.0 ?m). This investigation can hopefully offer an effective way of realizing high performance QDSSCs and QD growth/installation in other nanostructures as well. PMID:24281658

Tao, Liang; Xiong, Yan; Liu, Hong; Shen, Wenzhong

2014-01-21

231

Double functions of porous TiO2 electrodes on CH3NH3PbI3 perovskite solar cells: Enhancement of perovskite crystal transformation and prohibition of short circuiting  

NASA Astrophysics Data System (ADS)

In order to analyze the crystal transformation from hexagonal PbI2 to CH3NH3PbI3 by the sequential (two-step) deposition process, perovskite CH3NH3PbI3 layers were deposited on flat and/or porous TiO2 layers. Although the narrower pores using small nanoparticles prohibited the effective transformation, the porous-TiO2 matrix was able to help the crystal transformation of PbI2 to CH3NH3PbI3 by sequential two-step deposition. The resulting PbI2 crystals in porous TiO2 electrodes did not deteriorate the photovoltaic effects. Moreover, it is confirmed that the porous TiO2 electrode had served the function of prohibiting short circuits between working and counter electrodes in perovskite solar cells.

Murugadoss, Govindhasamy; Mizuta, Gai; Tanaka, Soichiro; Nishino, Hitoshi; Umeyama, Tomokazu; Imahori, Hiroshi; Ito, Seigo

2014-08-01

232

Adsorption of organic dyes on TiO2 surfaces in dye-sensitized solar cells: interplay of theory and experiment.  

PubMed

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 ?-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/simulation and experiments appears to be the key to further DSCs progress, both concerning the design of new dye sensitizers and their interaction with the semiconductor and with the solution environment and/or an electrolyte upon adsorption onto the semiconductor. PMID:23108504

Anselmi, Chiara; Mosconi, Edoardo; Pastore, Mariachiara; Ronca, Enrico; De Angelis, Filippo

2012-12-14

233

An investigation on electron behavior employing vertically-aligned TiO2 nanotube electrodes for dye-sensitized solar cells  

NASA Astrophysics Data System (ADS)

Anodically grown TiO2 nanotubes (TONTs), approximately 13 µm thick, were prepared on an ethylene glycol-based electrolyte containing 0.25 wt% NH4F with extremely small amounts of water. A Ti substrate was pretreated electrochemically, which affected the TONT surface morphology. The TONT (abbreviated as two-step TONT) grown on the pretreated substrate showed a uniform surface morphology with an interconnected nanotubular structure, while the surface morphology of the TONT (abbreviated as one-step TONT) formed on the bare substrate was quite rough. The photocurrent (8.4 mA cm-2) of the two-step TONT-based dye-sensitized solar cell (DSSC) was improved by 14% compared to that (7.2 mA cm-2) of the one-step TONT-based DSSC. This improvement was attributed mainly to the increased light capturing efficiency, that is, light absorbance by a dye-sensitized TONT film. The discrepancy between the increasing light capturing yield (21%) and overall photocurrent (14%) was attributed to the slower electron transport rate as a result of the large surface area and lateral movement along the three-dimensional network. Therefore, the improved photocurrent of the two-step TONT-based DSSC led to an enhancement (12.5%) of the overall power conversion efficiency.

Kang, Soon Hyung; Kim, Hyun Sik; Kim, Jae-Yup; Sung, Yung-Eun

2009-09-01

234

Tailoring of boron-doped MnTe semiconductor-sensitized TiO2 photoelectrodes as near-infrared solar cell devices  

NASA Astrophysics Data System (ADS)

We studied the photovoltaic performance of a new tailoring of boron-doped MnTe semiconductor-sensitized solar cells (B-doped MnTe SSCs). The B-doped MnTe semiconductor was grown on TiO2 using two-stages of the successive ionic layer adsorption and reaction (SILAR) technique as a photoelectrode. The phase of the boron-doped MnTe and MnTe2 semiconductor as sensitizers were characterized with ˜20-50 nm in diameter. The B-doped MnTe(5) exhibited the best efficiency of 0.04%, compared to that of the undoped sample of 0.006%. In addition, the band gaps of 1.30 and 1.26 eV were determined for the undoped and B-doped MnTe NPs, respectively. The change in the band gap after boron doping was performed due to crystal quality improvement and the larger size of the MnTe NPs, leading to a broader absorption of the sensitizer and a noticeable improvement in the photovoltaic performance. This kind of semiconductor and synthesis procedure can be applied for further improvement in a higher efficiency and more stability in SSCs.

Tubtimtae, Auttasit; Hongto, Timakorn; Hongsith, Kritsada; Choopun, Supab

2014-02-01

235

High-performance large-scale flexible dye-sensitized solar cells based on anodic TiO2 nanotube arrays.  

PubMed

A simple strategy to fabricate flexible dye-sensitized solar cells involves the use of photoanodes based on TiO2 nanotube (TNT) arrays with rear illumination. The TNT films (tube length ?35 ?m) were produced via anodization, and sensitized with N719 dye for photovoltaic characterization. Pt counter electrodes of two types were used: a conventional FTO/glass substrate for a device of rigid type and an ITO/PEN substrate for a device of flexible type. These DSSC devices were fabricated into either a single-cell structure (active area 3.6×0.5 cm2) or a parallel module containing three single cells (total active area 5.4 cm2). The flexible devices exhibit remarkable performance with efficiencies ?=5.40% (single cell) and 4.77% (parallel module) of power conversion, which outperformed their rigid counterparts with ?=4.87% (single cell) and 4.50% (parallel model) under standard one-sun irradiation. The flexible device had a greater efficiency of conversion of incident photons to current and a broader spectral range than the rigid device; a thinner electrolyte layer for the flexible device than for the rigid device is a key factor to improve the light-harvesting ability for the TNT-DSSC device with rear illumination. Measurements of electrochemical impedance spectra show excellent catalytic activity and superior diffusion characteristics for the flexible device. This technique thus provides a new option to construct flexible photovoltaic devices with large-scale, light-weight, and cost-effective advantages for imminent applications in consumer electronics. PMID:24050628

Jen, Hsiu-Ping; Lin, Meng-Hung; Li, Lu-Lin; Wu, Hui-Ping; Huang, Wei-Kai; Cheng, Po-Jen; Diau, Eric Wei-Guang

2013-10-23

236

Dye-sensitized TiO2 solar cells using imidazolium-type ionic liquid crystal systems as effective electrolytes.  

PubMed

A novel ionic liquid crystal (ILC) system (C(12)MImI/I(2)) with a smectic A phase used as an electrolyte for a dye-sensitized solar cell (DSSC) showed the higher short-circuit current density (J(SC)) and the higher light-to-electricity conversion efficiency than the system using the non-liquid crystalline ionic liquid (C(11)MImI/I(2)), due to the higher conductivity of ILC. To investigate charge transport properties of the electrolytes in detail, the exchange reaction-based diffusion coefficients (D(ex)) were evaluated. The larger D(ex) value of ILC supported that the higher conductivity of ILC is attributed to the enhancement of the exchange reaction between iodide species. As a result of formation of the two-dimensional electron conductive pathways organized by the localized I(3)- and I- at S(A) layers, the concentration of polyiodide species exemplified by I(m)- (m = 5, 7, ...) was higher in C(12)MImI/I(2). However, as the increment of the concentration of polyiodide species is less than that of D(ex), the contribution of a two-dimensional structure of the conductive pathway through the increase of collision frequency between iodide species was proposed. Furthermore, a quasi-solid-state ionic liquid crystal DSSC was successfully fabricated by employing a low molecular gelator. Addition of the 5.0 g/L gelator to ILC improved light-to-electricity conversion efficiency through the increase of J(SC) due to the enhancement of the conductivity in C(12)MImI/I(2)-gel. PMID:17474701

Yamanaka, Noriyo; Kawano, Ryuji; Kubo, Wataru; Masaki, Naruhiko; Kitamura, Takayuki; Wada, Yuji; Watanabe, Masayoshi; Yanagida, Shozo

2007-05-10

237

Low-temperature fabrication of TiO(2) electrodes for flexible dye-sensitized solar cells using an electrospray process.  

PubMed

Hierarchically structured TiO2 (HS-TiO2) was prepared on a flexible ITO-PEN (polyethylene naphthalate) substrate via electrospray deposition using a commercially available TiO2 nanocrystalline powder in order to fabricate flexible DSSCs under low-temperature (<150 °C) conditions. The cell efficiency increased when using flexible ITO-PEN substrates post-treated by either a mechanical compression treatment or a chemical sintering treatment using titanium n-tetrabutoxide (TTB). The mechanical compression treatment reduced the surface area and porosity of the HS-TiO2; however, this treatment improved the interparticle connectivity and physical adhesion between the HS-TiO2 and ITO-PEN substrate, which increased the photocurrent density of the as-pressed HS-TiO2 cells. The electron diffusion coefficients of the as-pressed HS-TiO2 improved upon compression treatment, whereas the recombination lifetimes remained unchanged. An additional chemical sintering post-treatment involving TTB was tested for its effects on DSSC efficiency. The freshly coated TiO2 submitted to TTB hydrolysis in water at 100 °C yielded an anatase phase. TTB treatment of the HS-TiO2 cell after compression treatment yielded faster electron diffusion, providing an efficiency of 5.57% under 100 mW cm(-2), AM 1.5 global illumination. PMID:22658770

Lee, Horim; Hwang, Daesub; Jo, Seong Mu; Kim, Dongho; Seo, Yongsok; Kim, Dong Young

2012-06-27

238

A low-cost, high-efficiency solar cell based on dye-sensitized colloidal TiO2 films  

Microsoft Academic Search

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

Brian O'Regan; Michael Graetzel

1991-01-01

239

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

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.

Koch, Rainer; Lipton, Andrew S.; Filipek, S.; Renugopalakrishnan, Venkatesan M.

2011-06-01

240

Solar Energy Materials & Solar Cells 87 (2005) 181196 Optical filters from SiO2 and TiO2 multi-layers  

E-print Network

­gel; Spin coating; Anti-reflective (AR) filter; Reflective filter; SiO2; TiO2; Densification model 1-layer anti-reflective (AR) filters for the near­infrared region, and a nine- layer reflective filter-layers using sol­gel spin coating method D. Saygin Hinczewskia , M. Hinczewskib,c , F.Z. Tepehana , G

Thirumalai, Devarajan

241

Role of electrolytes on charge recombination in dye-sensitized TiO(2) solar cell (1): the case of solar cells using the I(-)/I(3)(-) redox couple.  

PubMed

Performance of dye-sensitized solar cells (DSCs) was investigated depending on the compositions of the electrolyte, i.e., the electrolyte with a different cation such as Li(+), tetra-n-butylammonium (TBA(+)), or 1,2-dimethyl-3-propylimidazolium (DMPIm(+)) in various concentrations, with and without 4-tert-butylpyridine (tBP), and with various concentrations of the I(-)/I(3)(-) redox couple. Current-voltage characteristics, electron lifetime, and electron diffusion coefficient were measured to clarify the effects of the constituents in the electrolyte on the charge recombination kinetics in the DSCs. Shorter lifetimes were found for the DSCs employing adsorptive cations of Li(+) and DMPIm(+) than for a less-adsorptive cation of TBA(+). On the other hand, the lifetimes were not influenced by the concentrations of the cations in the solutions. Under light irradiation, open-circuit voltages of DSCs decreased in the order of TBA(+)> DMPIm(+) > Li(+), and also decreased with the increase of [Li(+)]. The decreases of open-circuit voltage (V(oc)) were attributed to the positive shift of the TiO(2) conduction band potential (CBP) by the surface adsorption of DMPIm(+) and Li(+). These results suggest that the difference of the free energies between that of the electrons in the TiO(2) and of I(3)(-) has little influence on the electron lifetimes in the DSCs. The shorter lifetime with the adsorptive cations was interpreted with the thickness of the electrical double layer formed by the cations, and the concentration of I(3)(-) in the layer, i.e., TBA(+) formed thicker double layer resulting in lower concentration of I(3)(-) on the surface of the TiO(2). The addition of 4-tert-butylpyridine (tBP) in the presence of Li(+) or TBA(+) showed no significant influence on the lifetime. The increase of V(oc) by the addition of tBP into the electrolyte containing Li(+) and the I(-)/I(3)(-) redox couple was mainly attributed to the shift of the CBP back to the negative potential by reducing the amount of adsorbed Li cations. PMID:16851382

Nakade, Shogo; Kanzaki, Taisuke; Kubo, Wataru; Kitamura, Takayuki; Wada, Yuji; Yanagida, Shozo

2005-03-01

242

Formation of 'single walled' TiO2 nanotubes with significantly enhanced electronic properties for higher efficiency dye-sensitized solar cells.  

PubMed

The present work establishes a process for the anodic growth of self-organized TiO(2) nanotubes with a single-walled morphology. This yields not only a much more defined tube geometry but also provides a significant increase in properties and prospect for a wide range of TiO(2) nanotube applications. PMID:23385481

Mirabolghasemi, Hamed; Liu, Ning; Lee, Kiyoung; Schmuki, Patrik

2013-03-11

243

Efficient quantum dot-sensitized solar cell with polystyrene-modified TiO 2 photoanode and with guanidine thiocyanate in its polysulfide electrolyte  

Microsoft Academic Search

Monodispersed polystyrene (PS, ca. 300nm) latex particles are incorporated into a TiO2 film. A polystyrene-modified TiO2 film (M-TiO2) with micro-cluster structure, containing micro\\/nano-composite pores is thus obtained after sintering. Cadmium sulfide (CdS) quantum dots (CdS-QDs) are accumulated over M-TiO2 and bare TiO2 films (B-TiO2) by successive ionic layer adsorption and reaction (SILAR); we designate these films as M-TiO2\\/CdS and B-TiO2\\/CdS,

Chen-Yu Chou; Chuan-Pei Lee; R. Vittal; Kuo-Chuan Ho

2011-01-01

244

Surface Passivation of Nanoporous TiO2 via Atomic Layer Deposition of ZrO2 for Solid-State Dye-Sensitized Solar Cell Applications  

E-print Network

to the spiro-OMeTAD. Introduction Dye-sensitized solar cells (DSCs) based on mesoporous titania and liquid/detrapping model, where an electron moves from trap-to-trap until collection at the cell's transparent conducting-Sensitized Solar Cell Applications Tina C. Li, Ma�rcio S. Go�es,,� Francisco Fabregat-Santiago,*, Juan Bisquert

245

Graphene-embedded 3D TiO2 inverse opal electrodes for highly efficient dye-sensitized solar cells: morphological characteristics and photocurrent enhancement.  

PubMed

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

Kim, Hye-Na; Yoo, Haemin; Moon, Jun Hyuk

2013-05-21

246

Impedance analysis for dye-sensitized solar cells based on TiO2 electrode coated with Cr2O3  

NASA Astrophysics Data System (ADS)

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.

Li, Y.; Zhuang, Q. C.; Wang, H. T.; Xu, X. Q.; Qiang, Y. H.; Fang, L.

2013-09-01

247

Graphene-embedded 3D TiO2 inverse opal electrodes for highly efficient dye-sensitized solar cells: morphological characteristics and photocurrent enhancement  

NASA Astrophysics Data System (ADS)

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 JSC, as determined by the photovoltaic parameters and the electrochemical impedance spectroscopy analysis.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 JSC, as determined by the photovoltaic parameters and the electrochemical impedance spectroscopy analysis. Electronic supplementary information (ESI) available. See DOI: 10.1039/c3nr33672g

Kim, Hye-Na; Yoo, Haemin; Moon, Jun Hyuk

2013-05-01

248

The effect of TiCl4-treated TiO2 compact layer on the performance of dye-sensitized solar cell  

E-print Network

, several metaleoxide films with higher conduction-band edges than TiO2, such as Al2O3, MgO, ZnO, and Nb2O5 (Solaronix) for 24 h. For a counter electrode, two holes were drilled in FTO substrate, and Pt thin film, such as sputtering, spin-coating, chemical vapor deposition, and hydrolysis [10e20]. In particular, the TiO2 compact

Park, Byungwoo

249

Assembly of CdS quantum dots onto mesoscopic TiO(2) films for quantum dot-sensitized solar cell applications.  

PubMed

Colloidal cadmium sulfide (CdS) quantum dots (QDs) were prepared and surface modified by mercaptosuccinic acid (MSA) to render a surface with carboxylic acid groups (MSA-CdS). The MSA-CdS QDs were then assembled onto bare TiO(2) mesoporous films using the carboxylic groups/TiO(2) interaction. The TiO(2) film was also surface modified by 3-mercaptopropyl trimethoxysilane (MPTMS) or 3-aminopropyl-methyl diethoxysilane (APMDS) to prepare, respectively, a thiol (-SH) or amino (-NH(2)) terminated surface for binding with the CdS QDs. The experimental results showed that the MPTMS-modified film has the highest adsorption rate and adsorption amount to the CdS QDs, attributable to the strong thiol/CdS interaction. In contrast, the adsorption rate and incorporated amount of the QDs on the bare TiO(2) film are much lower than for the silane-modified films. The incident photon-to-current conversion efficiency (IPCE) obtained for the CdS-sensitized TiO(2) electrode was about 20% (at 400 nm) for the bare TiO(2), 13% for the MPTMS-TiO(2), and 6% for APMDS-TiO(2). The current-voltage measurement under dark conditions reveals a higher dark current on the MPTMS- and APMDS-modified electrodes, indicating a lower coverage ratio of CdS on these TiO(2) films. This result is attributed to the fast adsorption rate of CdS QDs on the bottleneck of a mesopore which inhibits the transport of the QDs deep into the inner region of a pore. For the bare TiO(2) film, the lower incorporated amount of CdS but higher energy conversion efficiency indicates the formation of a better-covered CdS QDs monolayer. The moderate adsorption rate of MSA-CdS QDs using the carboxylic acid/TiO(2) interaction is responsible for the efficient assembly of QDs onto the mesoporous TiO(2) films. PMID:21817508

Shen, Yu-Jen; Lee, Yuh-Lang

2008-01-30

250

Assembly of CdS quantum dots onto mesoscopic TiO2 films for quantum dot-sensitized solar cell applications  

NASA Astrophysics Data System (ADS)

Colloidal cadmium sulfide (CdS) quantum dots (QDs) were prepared and surface modified by mercaptosuccinic acid (MSA) to render a surface with carboxylic acid groups (MSA-CdS). The MSA-CdS QDs were then assembled onto bare TiO2 mesoporous films using the carboxylic groups/TiO2 interaction. The TiO2 film was also surface modified by 3-mercaptopropyl trimethoxysilane (MPTMS) or 3-aminopropyl-methyl diethoxysilane (APMDS) to prepare, respectively, a thiol (-SH) or amino (-NH2) terminated surface for binding with the CdS QDs. The experimental results showed that the MPTMS-modified film has the highest adsorption rate and adsorption amount to the CdS QDs, attributable to the strong thiol/CdS interaction. In contrast, the adsorption rate and incorporated amount of the QDs on the bare TiO2 film are much lower than for the silane-modified films. The incident photon-to-current conversion efficiency (IPCE) obtained for the CdS-sensitized TiO2 electrode was about 20% (at 400 nm) for the bare TiO2, 13% for the MPTMS-TiO2, and 6% for APMDS-TiO2. The current-voltage measurement under dark conditions reveals a higher dark current on the MPTMS- and APMDS-modified electrodes, indicating a lower coverage ratio of CdS on these TiO2 films. This result is attributed to the fast adsorption rate of CdS QDs on the bottleneck of a mesopore which inhibits the transport of the QDs deep into the inner region of a pore. For the bare TiO2 film, the lower incorporated amount of CdS but higher energy conversion efficiency indicates the formation of a better-covered CdS QDs monolayer. The moderate adsorption rate of MSA-CdS QDs using the carboxylic acid/TiO2 interaction is responsible for the efficient assembly of QDs onto the mesoporous TiO2 films.

Shen, Yu-Jen; Lee, Yuh-Lang

2008-01-01

251

Designed synthesis of SiO2/TiO2 core/shell structure as light scattering material for highly efficient dye-sensitized solar cells.  

PubMed

SiO2/TiO2 core/shell nanoparticles (STCS-NPs) with diameters of 110, 240, and 530 nm were fabricated to investigate the influence of the size and refractive index of light-scattering particles on light-scattering properties. The optical properties of STCS-NPs were evaluated and compared with SiO2-NPs and TiO2-NPs. The structure of STCS-NPs, consisting of a low refractive index core and high refractive index shell, provides efficient light scattering. The optimized anode film with STCS-NPs had ca. 20% improved power conversion efficiency (PCE). PMID:23635382

Son, Suim; Hwang, Sun Hye; Kim, Chanhoi; Yun, Ju Young; Jang, Jyongsik

2013-06-12

252

Full Printable Processed Mesoscopic CH3NH3PbI3/TiO2 Heterojunction Solar Cells with Carbon Counter Electrode  

NASA Astrophysics Data System (ADS)

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.

Ku, Zhiliang; Rong, Yaoguang; Xu, Mi; Liu, Tongfa; Han, Hongwei

2013-11-01

253

Full Printable Processed Mesoscopic CH3NH3PbI3/TiO2 Heterojunction Solar Cells with Carbon Counter Electrode  

PubMed Central

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

Ku, Zhiliang; Rong, Yaoguang; Xu, Mi; Liu, Tongfa; Han, Hongwei

2013-01-01

254

Growth of Aligned Single-Crystalline Rutile TiO2 Nanowires on Arbitrary Substrates and Their Application in Dye-Sensitized Solar Cells  

E-print Network

(100), Si(111), and glass rods. By controlling the growth parameters such as growth temperature of TiO2 nanowires on both FTO and glass substrates. Effects of various titanium precursors on the growth witnessed limited progress toward a low-temperature synthesis protocol allowing for its growth on arbitrary

Zhou, Chongwu

255

Mesoscopic TiO2/CH3NH3PbI3 perovskite solar cells with new hole-transporting materials containing butadiene derivatives.  

PubMed

Two new triphenylamine-based hole-transporting materials (HTMs) containing butadiene derivatives are employed in CH3NH3PbI3 perovskite solar cells. Up to 11.63% of power conversion efficiency (PCE) has been achieved. Advantages such as easy synthesis, low cost and relatively good cell performance exhibit a possibility for commercial applications in the future. PMID:24841233

Lv, Songtao; Han, Liying; Xiao, Junyan; Zhu, Lifeng; Shi, Jiangjian; Wei, Huiyun; Xu, Yuzhuan; Dong, Juan; Xu, Xin; Li, Dongmei; Wang, Shirong; Luo, Yanhong; Meng, Qingbo; Li, Xianggao

2014-07-01

256

A review on highly ordered, vertically oriented TiO 2 nanotube arrays: Fabrication, material properties, and solar energy applications  

Microsoft Academic Search

We review the fabrication, properties, and solar energy applications of highly ordered TiO2 nanotube arrays made by anodic oxidation of titanium in fluoride-based electrolytes. The material architecture has proven to be of great interest for use in water photoelectrolysis, photocatalysis, heterojunction solar cells, and gas sensing. We examine the ability to fabricate nanotube arrays of different shape (cylindrical, tapered), pore

Gopal K. Mor; Oomman K. Varghese; Maggie Paulose; Karthik Shankar; Craig A. Grimes

2006-01-01

257

Photocurrent Induced by Conducting Channels of Hole Transporting Layer to Adjacent Photoactive Perovskite Sensitized TiO2 Thin Film: Solar Cell Paradigm.  

PubMed

A high performance perovskite solar cell was fabricated using the distinguished morphology of polyaniline nanoparticles (PANI-NPs) as an efficient hole transporting layer (HTL) with methylammonium lead iodide perovskite (CH3NH3PbI3) as sensitizer. PANI-NPs were simply synthesized by the oxidative chemical polymerization of aniline monomer at 0-5 °C. A reasonable solar-to-electricity conversion efficiency of ?6.29% with a high short circuit current (JSC) of ?17.97 mA/cm(2) and open circuit voltage (VOC) of ?0.877 V were accomplished by Ag/PANI-NPs/CH3NH3PbI3/mp-anatase-TiO2/bl-TiO2/FTO perovskite solar cell. The transient photocurrent and photovoltage studies revealed that the fabricated solar cell showed better charge transport time, diffusion coefficient, diffusion length, and charge collection efficiency. Herein, the use of PANI-NPs as the HTL improved the charge carrier generation and the charge collection efficiency of the fabricated solar cell. PMID:25296009

Ameen, Sadia; Akhtar, M Shaheer; Seo, Hyung-Kee; Shin, Hyung-Shik

2014-11-01

258

A maskless synthesis of TiO2-nanofiber-based hierarchical structures for solid-state dye-sensitized solar cells with improved performance  

PubMed Central

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

2014-01-01

259

Er3+ and Yb3+ co-doped TiO2-xFx up-conversion luminescence powder as a light scattering layer with enhanced performance in dye sensitized solar cells  

NASA Astrophysics Data System (ADS)

Er3+ and Yb3+ co-doped TiO2-xFx up-conversion luminescence powder (UC-TiO2-xFx) was fabricated via hydrothermal method and calcined at 500 °C for 2 h. The prepared powders were characterized by SEM, XRD, PL, UC-PL, UV-Vis, SPS and IPCE spectra. The results showed that UC-TiO2-xFx possessed the property of up-conversion, increasing the percentage of visible light that can be absorbed by N719 dyes; it got a lower band gap energy which contributed to a faster electrons injection and decreased the radiative recombination process of photo-generated electrons and holes in TiO2; and adequate F-doping could enhance the performance of luminescence and widened the light absorption in visible light range, but excessive F-doping could cause blue-shift. We applied the UC-TiO2-xFx into dye sensitized solar cell (DSSC), as a light scattering layer for its special morphology, to gain a higher light harvesting and a lower light loss so as to achieve a satisfied DSSC efficiency. Under the simulated solar irradiation of 100 mW cm-2 (AM1.5G), a short-circuit current density of 16.3 mA cm-2, an open-circuit voltage of 0.725 V and an overall energy conversion efficiency of 7.08% were obtained by introducing this light scattering layer.

Yu, Jia; Yang, Yulin; Fan, Ruiqing; Zhang, Huijie; Li, Liang; Wei, Liguo; Shi, Yan; Pan, Kai; Fu, Honggang

2013-12-01

260

WO3/TiO2 nanotube photoanodes for solar water splitting with simultaneous wastewater treatment.  

SciTech Connect

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.

Reyes, Karla Rosa; Robinson, David B.

2013-05-01

261

Array of solid-state dye-sensitized solar cells with micropatterned TiO2 nanoparticles for a high-voltage power source  

NASA Astrophysics Data System (ADS)

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.

Cho, Seong-Min; Park, Hea-Lim; Kim, Min-Hoi; Kim, Se-Um; Lee, Sin-Doo

2013-11-01

262

High efficiency solid-state sensitized solar cell-based on submicrometer rutile TiO2 nanorod and CH3NH3PbI3 perovskite sensitizer.  

PubMed

We report a highly efficient solar cell based on a submicrometer (~0.6 ?m) rutile TiO2 nanorod sensitized with CH3NH3PbI3 perovskite nanodots. Rutile nanorods were grown hydrothermally and their lengths were varied through the control of the reaction time. Infiltration of spiro-MeOTAD hole transport material into the perovskite-sensitized nanorod films demonstrated photocurrent density of 15.6 mA/cm(2), voltage of 955 mV, and fill factor of 0.63, leading to a power conversion efficiency (PCE) of 9.4% under the simulated AM 1.5G one sun illumination. Photovoltaic performance was significantly dependent on the length of the nanorods, where both photocurrent and voltage decreased with increasing nanorod lengths. A continuous drop of voltage with increasing nanorod length correlated with charge generation efficiency rather than recombination kinetics with impedance spectroscopic characterization displaying similar recombination regardless of the nanorod length. PMID:23672481

Kim, Hui-Seon; Lee, Jin-Wook; Yantara, Natalia; Boix, Pablo P; Kulkarni, Sneha A; Mhaisalkar, Subodh; Grätzel, Michael; Park, Nam-Gyu

2013-06-12

263

A new method to disperse CdS quantum dot-sensitized TiO2 nanotube arrays into P3HT:PCBM layer for the improvement of efficiency of inverted polymer solar cells  

PubMed Central

We report that the efficiency of ITO/nc-TiO2/P3HT:PCBM/MoO3/Ag inverted polymer solar cells (PSCs) can be improved by dispersing CdS quantum dot (QD)-sensitized TiO2 nanotube arrays (TNTs) in poly (3-hexylthiophene) and [6,6]-phenyl-C61-butyric acid methyl ester (P3HT:PCBM) layer. The CdS QDs are deposited on the TNTs by a chemical bath deposition method. The experimental results show that the CdS QD-sensitized TNTs (CdS/TNTs) do not only increase the light absorption of the P3HT:PCBM layer but also reduce the charge recombination in the P3HT:PCBM layer. The dependence of device performances on cycles of CdS deposition on the TNTs was investigated. A high power conversion efficiency (PCE) of 3.52% was achieved for the inverted PSCs with 20 cyclic depositions of CdS on TNTs, which showed a 34% increase compared to the ITO/nc-TiO2/P3HT:PCBM/MoO3/Ag device without the CdS/TNTs. The improved efficiency is attributed to the improved light absorbance and the reduced charge recombination in the active layer. PMID:24936158

2014-01-01

264

CdS sensitized 3D hierarchical TiO2/ZnO heterostructure for efficient solar energy conversion  

PubMed Central

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

Zheng, Zhaoke; Xie, Wen; Lim, Zhi Shiuh; You, Lu; Wang, Junling

2014-01-01

265

Homogeneous Photosensitization of Complex TiO2 Nanostructures for Efficient Solar Energy Conversion  

PubMed Central

TiO2 nanostructures-based photoelectrochemical (PEC) cells are under worldwide attentions as the method to generate clean energy. For these devices, narrow-bandgap semiconductor photosensitizers such as CdS and CdSe are commonly used to couple with TiO2 in order to harvest the visible sunlight and to enhance the conversion efficiency. Conventional methods for depositing the photosensitizers on TiO2 such as dip coating, electrochemical deposition and chemical-vapor-deposition suffer from poor control in thickness and uniformity, and correspond to low photocurrent levels. Here we demonstrate a new method based on atomic layer deposition and ion exchange reaction (ALDIER) to achieve a highly controllable and homogeneous coating of sensitizer particles on arbitrary TiO2 substrates. PEC tests made to CdSe-sensitized TiO2 inverse opal photoanodes result in a drastically improved photocurrent level, up to ~15.7 mA/cm2 at zero bias (vs Ag/AgCl), more than double that by conventional techniques such as successive ionic layer adsorption and reaction. PMID:22693653

Luo, Jingshan; Karuturi, Siva Krishna; Liu, Lijun; Su, Liap Tat; Tok, Alfred Iing Yoong; Fan, Hong Jin

2012-01-01

266

A facile and versatile method for preparation of colored TiO2 with enhanced solar-driven photocatalytic activity  

NASA Astrophysics Data System (ADS)

Colored TiO2 has attracted enormous attention due to its visible light absorption and excellent photocatalytic activity. In this report, we develop a simple and facile solid-state chemical reduction approach for a large-scale production of colored TiO2 at mild temperature (300-350 °C). The obtained sample possesses a crystalline core/amorphous shell structure (TiO2@TiO2-x). The oxygen vacancy results in the formation of a disordered TiO2-x shell on the surface of TiO2 nanocrystals. XPS and theoretical calculation results indicate that valence band tail and vacancy band below the conduction band minimum appear for the TiO2-x, which implies that the TiO2@TiO2-x nanocrystal has a narrow band gap and therefore leads to a broad visible light absorption. Oxygen vacancy in a proper concentration promotes the charge separation of photogenerated carriers, which improves the photocatalytic activity of TiO2@TiO2-x nanocrystals. This facile and general method could be potentially used for large scale production of colored TiO2 with remarkable enhancement in the visible light absorption and solar-driven H2 production.Colored TiO2 has attracted enormous attention due to its visible light absorption and excellent photocatalytic activity. In this report, we develop a simple and facile solid-state chemical reduction approach for a large-scale production of colored TiO2 at mild temperature (300-350 °C). The obtained sample possesses a crystalline core/amorphous shell structure (TiO2@TiO2-x). The oxygen vacancy results in the formation of a disordered TiO2-x shell on the surface of TiO2 nanocrystals. XPS and theoretical calculation results indicate that valence band tail and vacancy band below the conduction band minimum appear for the TiO2-x, which implies that the TiO2@TiO2-x nanocrystal has a narrow band gap and therefore leads to a broad visible light absorption. Oxygen vacancy in a proper concentration promotes the charge separation of photogenerated carriers, which improves the photocatalytic activity of TiO2@TiO2-x nanocrystals. This facile and general method could be potentially used for large scale production of colored TiO2 with remarkable enhancement in the visible light absorption and solar-driven H2 production. Electronic supplementary information (ESI) available: More XRD, UV-Vis spectra, XPS, SEM, TEM and photocatalytic degradation of MO. See DOI: 10.1039/c4nr02677b

Tan, Huaqiao; Zhao, Zhao; Niu, Mang; Mao, Chengyu; Cao, Dapeng; Cheng, Daojian; Feng, Pingyun; Sun, Zaicheng

2014-08-01

267

UV and Solar TiO2 Photocatalysis of Brevetoxins (PbTxs)  

PubMed Central

Karenia brevis, the harmful alga associated with red tide, produces brevetoxins (PbTxs). Exposure to these toxins can have a negative impact on marine wildlife and serious human health consequences. The elimination of PbTxs is critical to protect the marine environment and human health. TiO2 photocatalysis under 350 nm and solar irradiation leads to significant degradation of PbTxs via first order kinetics. ELISA results demonstrate TiO2 photocatalysis leads to a significant decrease in the bioactivity of PbTxs as a function of treatment time. Experiments conducted in the presence of synthetic seawater, humic material and a hydroxyl scavenger showed decreased degradation. PbTxs are highly hydrophobic and partition to organic microlayer on the ocean surface. Acetonitrile was employed to probe the influence of an organic media on the TiO2 photocatalysis of PbTxs. Our results indicate TiO2 photocatalysis may be applicable for the degradation of PbTxs. PMID:19931554

Khan, Urooj; Benabderrazik, Nadia; Bourdelais, Andrea J.; Baden, Daniel G.; Rein, Kathleen; Gardinali, Piero R.; Arroyo, Luis; O’Shea, Kevin E.

2012-01-01

268

Solar photocatalytic activity of TiO2 modified with WO3 on the degradation of an organophosphorus pesticide.  

PubMed

In this study, the solar photocatalytic activity (SPA) of WO3/TiO2 photocatalysts synthesized by the sol-gel method with two different percentages of WO3 (2 and 5%wt) was evaluated using malathion as a model contaminant. For comparative purpose bare TiO2 was also prepared by sol-gel process. The powders were characterized by X-ray diffraction (XRD), Raman spectroscopy, diffuse reflectance UV-vis spectroscopy (DRUV-vis), specific surface area by the BET method (SSABET), scanning electron microscopy (SEM), high resolution transmission electron microscopy (HRTEM) and scanning transmission electron microscopy with a high annular angle dark field detector (STEM-HAADF). The XRD, Raman, HRTEM and STEM-HAADF analyses indicated that WO3 was present as a monoclinic crystalline phase with nanometric cluster sizes (1.1 ± 0.1 nm for 2% WO3/TiO2 and 1.35 ± 0.3 nm for 5% WO3/TiO2) and uniformly dispersed on the surface of TiO2. The particle size of the materials was 19.4 ± 3.3 nm and 25.6 ± 3 nm for 2% and 5% WO3/TiO2, respectively. The SPA was evaluated on the degradation of commercial malathion pesticide using natural solar light. The 2% WO3/TiO2 photocatalyst exhibited the best photocatalytic activity achieving 76% of total organic carbon (TOC) abatement after 300 min compared to the 5% WO3/TiO2 and bare TiO2 photocatalysts, which achieved 28 and 47% mineralization, respectively. Finally, experiments were performed to assess 2% WO3/TiO2 catalyst activity on repeated uses; after several successive cycles its photocatalytic activity was retained showing long-term stability. PMID:23993423

Ramos-Delgado, N A; Gracia-Pinilla, M A; Maya-Treviño, L; Hinojosa-Reyes, L; Guzman-Mar, J L; Hernández-Ramírez, A

2013-12-15

269

Investigation of Solar Energy Transfer through Plasmonic Au Nanoparticle-doped Sol-derived TiO2 Thin Films in Photocatalysis and Photovoltaics  

NASA Astrophysics Data System (ADS)

Titanium Dioxide (TiO2) films were elaborated using the Sol-Gel technique and subsequently used to study plasmonic photovoltaic and photocatalytic energy transfer enhancement mechanisms. TiO2 was chosen because of the unique optical and electrical properties it possesses as well as its ease of preparation and operational stability. The properties of sol-elaborated films vary significantly with processing environment and technique, and the sol formula; a systematic investigation of these variables enabled the selection of a consistent technique to produce relatively dense, crack-free TiO2 thin films. Localized Surface Plasmon Resonance (LSPR) energy transfer was investigated by integrating plasmonic Au nanoparticles into multi-layer wide-band gap semiconductor (TiO2) devices, and by doping strongly catalytic TiO2 anodes in a 3-electrode photochemical cell. An instant 3x photocurrent enhancement in the multilayer solar cell device was observed under 650nm light illumination, which suggests the presence of a resonant energy transfer. The focus of this work was to develop a systematic analysis of the actual mechanics of energy transfer responsible for the light-harvesting enhancements seen in previous studies of Au nanoparticle-TiO2 systems under visible illumination. This mechanism remains the subject of debate and models have been proposed by various researchers. A method is developed here to pinpoint the most influential of the proposed mechanisms.

Zelinski, Andrew

270

Solar TiO 2-assisted photocatalytic degradation of IGCC power station effluents using a Fresnel lens  

Microsoft Academic Search

The heterogeneous TiO2 assisted photocatalytic degradation of wastewater from a thermoelectric power station under concentrated solar light irradiation using a Fresnel lens has been studied. The efficiency of photocatalytic degradation was determined from the analysis of cyanide and formate removal.Firstly, the influence of the initial concentration of H2O2 and TiO2 on the degradation kinetics of cyanides and formates was studied

J. M. Monteagudo; A. Durán; J. Guerra; F. García-Peña; P. Coca

2008-01-01

271

Azo-dyes photocatalytic degradation in aqueous suspension of TiO 2 under solar irradiation  

Microsoft Academic Search

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 Almer??a” (PSA, Spain) were used as the photoreactors and two identical reacting systems allowed to perform photoreactivity runs

Vincenzo Augugliaro; Claudio Baiocchi; Alessandra Bianco Prevot; Elisa Garc??a-López; Vittorio Loddo; Sixto Malato; Giuseppe Marc??; Leonardo Palmisano; Marco Pazzi; Edmondo Pramauro

2002-01-01

272

Understanding the solar photo-catalytic activity of TiO 2-ITO nanocomposite deposited on low cost substrates  

NASA Astrophysics Data System (ADS)

In this work, we report on the photo-catalytic properties of TiO 2-ITO nanocomposite deposited on low cost conventional clay ceramic substrates. The nanocomposite was formed by spraying a solution prepared from the P25 TiO 2 powder (Degussa) mixed with an organometallic paste of a dissolved combination of indium and tin. A TiO 2-ITO powder-like nanocomposite was prepared for X-ray diffraction (XRD) and transmission electron microscopy (TEM) characterization. The mean particle size of the TiO 2-ITO nanocomposite was found to be larger than that of pure TiO 2. The optical features of TiO 2-ITO-based layers (deposited on glass substrates) were investigated using UV-vis spectroscopy. The TiO 2-ITO nanocomposite deposited layers were found to have higher light absorption than the P25 TiO 2 powder. The photo-catalytic properties of the TiO 2-ITO nanocomposite (deposited on low cost clay ceramic substrates) were tested under solar irradiation using a well-known polluting dye. It was shown that the TiO 2-ITO nanocomposite exhibits higher degradation rates towards the pollutant dye than the P25 TiO 2 powder. The optical band gap of the TiO 2-ITO nanocomposite (2.79 eV) was found to be lower than that of pure TiO 2 (3.1 eV), while ITO (indium tin oxide) has a band gap of about 4.2 eV. ITO was found to be entirely transparent to sun light, while it exhibits a slight photo-catalytic activity, signifying the possible existence of an indirect photo-catalysis phenomenon (sensitized semiconductor photocalysis) and potential degradation (oxidation) of the pollutant through electron transfer from the dye to conduction band of the semiconductor. All photo-catalytic activity results were discussed in light of the optical band gap of the various compounds.

Chorfi, H.; Zayani, G.; Saadoun, M.; Bousselmi, L.; Bessaïs, B.

2010-01-01

273

Pt deposited TiO2 catalyst fabricated by thermal decomposition of titanium complex for solar hydrogen production  

NASA Astrophysics Data System (ADS)

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.

Truong, Quang Duc; Le, Thanh Son; Ling, Yong-Chien

2014-12-01

274

Synthesis and characterization of N-doped TiO2 photocatalysts with tunable response to solar radiation  

NASA Astrophysics Data System (ADS)

Modification of the electronic structure of wide band gap semiconductors by anion doping is an effective strategy for the development of photocatalytic materials operating under solar light irradiation. In the present work, nitrogen-doped TiO2 photocatalysts of variable dopant content were synthesized by annealing a sol-gel derived TiO2 powder under flowing ammonia at temperatures in the range of 450-800 °C, and their physicochemical and optical properties were compared to those of undoped TiO2 samples calcined in air. Results show that materials synthesized at T = 450-600 °C contain relatively small amounts of dopant atoms and their colour varies from pale yellow to dark green due to the creation of localized states above the valence band of TiO2 and the formation of oxygen vacancies. Treatment with NH3 at T > 600 °C results in phase transformation of anatase to rutile, in a significant decrease of the specific surface area and in formation of TiN at the surface of the TiO2 particles. The resulting dark grey (T = 700 °C) and black (T = 800 °C) materials display strong absorption in both the visible and NIR regions, originating from partial reduction of TiO2 and formation of Ti3+ defect states. The present synthesis method enables tailoring of the electronic structure of the semiconductor and could be used for the development of solar light-responsive photocatalysts for photo(electro)chemical applications.

Petala, Athanasia; Tsikritzis, Dimitris; Kollia, Mary; Ladas, Spyridon; Kennou, Stella; Kondarides, Dimitris I.

2014-06-01

275

Europium-Doped TiO2 Hollow Nanoshells: Two-Photon Imaging of Cell Binding  

E-print Network

with cells and can cause DNA strand breaking with genotoxicity.16,20 This characteristic gives titaniaEuropium-Doped TiO2 Hollow Nanoshells: Two-Photon Imaging of Cell Binding Sergio Sandoval,,,� Jian free for functionalization and the core free for payload encapsulation. Amine

Kummel, Andrew C.

276

Nanoscale TiO2 and Fe2O3 Architectures for Solar Energy Conversion Schemes  

NASA Astrophysics Data System (ADS)

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 that annealing at various temperatures produces a-Fe 2O3 films with variable electronic properties and catalytic activities in the context of water oxidation. The study revealed that a-Fe2O3 are superior water oxidation catalysts (WOCs) relative to crystalline forms produced by high temperature annealing of the thin-films. This research has important implications in the conversion of sunlight into electricity, and then into hydrogen fuels.

Sedach, Pavel Anatolyvich

277

Effect of Polyethylene Glycol Modification of TiO2 Nanoparticles on Cytotoxicity and Gene Expressions in Human Cell Lines  

PubMed Central

Nanoparticles (NPs) are tiny materials used in a wide range of industrial and medical applications. Titanium dioxide (TiO2) is a type of nanoparticle that is widely used in paints, pigments, and cosmetics; however, little is known about the impact of TiO2 on human health and the environment. Therefore, considerable research has focused on characterizing the potential toxicity of nanoparticles such as TiO2 and on understanding the mechanism of TiO2 NP-induced nanotoxicity through the evaluation of biomarkers. Uncoated TiO2 NPs tend to aggregate in aqueous media, and these aggregates decrease cell viability and induce expression of stress-related genes, such as those encoding interleukin-6 (IL-6) and heat shock protein 70B’ (HSP70B’), indicating that TiO2 NPs induce inflammatory and heat shock responses. In order to reduce their toxicity, we conjugated TiO2 NPs with polyethylene glycol (PEG) to eliminate aggregation. Our findings indicate that modifying TiO2 NPs with PEG reduces their cytotoxicity and reduces the induction of stress-related genes. Our results also suggest that TiO2 NP-induced effects on cytotoxicity and gene expression vary depending upon the cell type and surface modification. PMID:22489177

Mano, Sharmy Saimon; Kanehira, Koki; Sonezaki, Shuji; Taniguchi, Akiyoshi

2012-01-01

278

Aperiodic TiO2 Nanotube Photonic Crystal: Full-Visible-Spectrum Solar Light Harvesting in Photovoltaic Devices  

NASA Astrophysics Data System (ADS)

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.

Guo, Min; Xie, Keyu; Wang, Yu; Zhou, Limin; Huang, Haitao

2014-09-01

279

Improving the efficiency of ITO/nc-TiO2/CdS/P3HT:PCBM/PEDOT:PSS/Ag inverted solar cells by sensitizing TiO2 nanocrystalline film with chemical bath-deposited CdS quantum dots  

NASA Astrophysics Data System (ADS)

An improvement in the power conversion efficiency (PCE) of the inverted organic solar cell (ITO/nc-TiO2/P3HT:PCBM/PEDOT:PSS/Ag) is realized by depositing CdS quantum dots (QDs) on a nanocrystalline TiO2 (nc-TiO2) film as a light absorption material and an electron-selective material. The CdS QDs were deposited via a chemical bath deposition (CBD) method. Our results show that the best PCE of 3.37% for the ITO/nc-TiO2/CdS/P3HT:PCBM/PEDOT:PSS/Ag cell is about 1.13 times that (2.98%) of the cell without CdS QDs (i.e., ITO/nc-TiO2/P3HT:PCBM/PEDOT:PSS/Ag). The improved PCE can be mainly attributed to the increased light absorption and the reduced recombination of charge carriers from the TiO2 to the P3HT:PCBM film due to the introduced CdS QDs.

Chen, Chong; Li, Fumin

2013-10-01

280

An efficient and novel porous nanosilica supported TiO2 photocatalyst for pesticide degradation using solar light.  

PubMed

A latex polymer of styrene-acrylic acid emulsion is used as a template for the synthesis of novel porous nanosilica (PNS) material. TiO(2) is dispersed over PNS by solid state dispersion and the composite materials are characterized by XRD, nitrogen adsorption-desorption isotherms, SEM and TEM measurements. The photocatalytic activities of the composite TiO(2)/PNS catalysts are evaluated for degradation of isoproturon pesticide in water with different parameters under solar light. Furthermore, commercial pesticide solutions containing imidacloprid and phosphamidon were also degraded successfully with the composite system using the same developed conditions for isoproturon degradation. The 5 wt% TiO(2)/PNS is found to be active in the present investigation. PMID:19596511

Phanikrishna Sharma, Mangalampalli V; Sadanandam, Gullapelli; Ratnamala, Ajjarapu; Durga Kumari, Valluri; Subrahmanyam, Machiraju

2009-11-15

281

Synthesis of nanoscale TiO2 and study of the effect of their crystal structure on single cell response.  

PubMed

To study the effect of nanoscale titanium dioxide (TiO(2)) on cell responses, we synthesized four modifications of the TiO(2) (amorphous, anatase, brookite, and rutile) capable of keeping their physicochemical characteristics in a cell culture medium. The modifications of nanoscale TiO(2) were obtained by hydrolysis of TiCl(4) and Ti(i-OC(3)H(7))(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 TiO(2) nanoparticles was studied. The hydrolysis methods providing the preparation of amorphous, anatase, brookite, and rutile modifications of TiO(2) nanoparticles 3-5?nm in size were selected. Examination of different forms of TiO(2) 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 TiO(2). 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

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

282

Synthesis of Nanoscale TiO2 and Study of the Effect of Their Crystal Structure on Single Cell Response  

PubMed Central

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

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

283

Quantum dot sensitized solar cells  

Microsoft Academic Search

Metal sulfide (CdS or PbS) quantum dots were synthesized in nanoporous TiO2 films for applications in solar energy conversion devices. Several electrolytes were investigated for the functioning redox activity in sandwich type regenerative solar cells, based on the quantum dots sensitized TiO2 film. A high IPCE was attained by optimizing the polysulfide electrolyte composition. The CdS QD shows a higher

Y. Tachibana; H. Y. Akiyama; K. Umekita; Y. Otsuka; T. Torimoto; S. Kuwabata

2008-01-01

284

Assessment of solar driven TiO2-assisted photocatalysis efficiency on amoxicillin degradation.  

PubMed

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. PMID:23900954

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

285

UVB Irradiation Enhances TiO2 Nanoparticle-induced Disruption of Calcium Homeostasis in Human Lens Epithelial Cells.  

PubMed

Currently, titanium dioxide nanoparticles (TiO2 NPs) have been widely used in various applications including cosmetics, food additives and biomedicine. However, there are few reports available using TiO2 NPs to treat ocular diseases. Posterior capsular opacification (PCO) is the most frequent complication after cataract surgery, which is induced by the proliferation and migration of lens epithelial cells. Thus, inhibiting the proliferation of lens epithelial cells will efficiently reduce the occurrence of PCO. In this study, we investigated the effects of TiO2 NPs on HLE B-3 cells with or without ultraviolet B (UVB) irradiation in vitro. We found that TiO2 NPs can inhibit HLE B-3 cell growth, cause the elevation of intracellular [Ca(2+) ], produce excessive reactive oxygen species (ROS), further reduce Ca(2+) -ATPase activity and decrease the expression of plasma membrane calcium ATPase 1 (PMCA1), finally disrupt the intracellular calcium homeostasis and induce cell damage. Importantly, UVB irradiation can apparently enhance these effects on HLE B-3 cells in the presence of TiO2 NPs. Taken together, the generation of excessive ROS and the disruption of intracellular calcium homeostasis may be both involved in TiO2 nanoparticle-induced HLE B-3 cell damage under UVB irradiation. PMID:25059545

Wu, Qiuxin; Guo, Dadong; Du, Yuxiang; Liu, Dongmei; Wang, Daoguang; Bi, Hongsheng

2014-11-01

286

Nano-structured TiO 2 films by plasma electrolytic oxidation combined with chemical and thermal post-treatments of titanium, for dye-sensitised solar cell applications  

Microsoft Academic Search

This paper demonstrates a new method to grow nano-structured TiO2 over a plasma electrolytically oxidised titanium surface. Microstructural characterisation by employing a variety of transmission electron microscopy techniques was carried out to explore the nano-scale structural changes due to the alkaline and thermal treatments. Photovoltaic performance was measured and this revealed the effect of microstructural changes. Such coatings can be

Po-Jen Chu; Shu-Yuan Wu; Keh-Chang Chen; Ju-Liang He; Aleksey Yerokhin; Allan Matthews

2010-01-01

287

Fabrication of a dye-sensitized solar cell containing a Mg-doped TiO2 electrode and a Br3(-)/Br- redox mediator with a high open-circuit photovoltage of 1.21 V.  

PubMed

A dye-sensitized solar cell (DSSC) fabricated by using a Mg(2+)-doped anatase-TiO(2) electrode with an alkoxysilyl dye and a Br(3)(-)/Br(-) electrolyte solution exhibited successfully a remarkably high open-circuit photovoltage over 1.2 V, demonstrating a new possibility of DSSCs as practical photovoltaic devices. PMID:23168717

Kakiage, Kenji; Tokutome, Toru; Iwamoto, Shinji; Kyomen, Toru; Hanaya, Minoru

2013-01-01

288

Aperiodic TiO2 Nanotube Photonic Crystal: Full-Visible-Spectrum Solar Light Harvesting in Photovoltaic Devices.  

PubMed

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

Guo, Min; Xie, Keyu; Wang, Yu; Zhou, Limin; Huang, Haitao

2014-01-01

289

Aperiodic TiO2 Nanotube Photonic Crystal: Full-Visible-Spectrum Solar Light Harvesting in Photovoltaic Devices  

PubMed Central

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

Guo, Min; Xie, Keyu; Wang, Yu; Zhou, Limin; Huang, Haitao

2014-01-01

290

Treatment of emerging contaminants in wastewater treatment plants (WWTP) effluents by solar photocatalysis using low TiO2 concentrations.  

PubMed

The optimal photocatalyst concentration for industrial wastewater treatment in current photoreactor designs is several hundreds of milligrams per liter. However, the elimination of emerging contaminants (ECs), which are present at extremely low concentrations in waste water treatment plants (WWTP) effluents might be accomplished at much lower catalyst (TiO(2)) concentrations. One of the main drawbacks of reducing catalyst loading below the optimum is the loss of useful photons which instead are transmitted through the TiO(2) suspension without being absorbed by the catalyst. Accordingly, in this work, laboratory and solar pilot-scale experiments were performed with real WWTP effluents to evaluate the kinetics of photocatalytic degradation of 52 emerging contaminants under realistic (ppb) concentrations. The analysis of the samples was accomplished by solid phase extraction (SPE) followed by liquid chromatography-mass spectrometry (LC-MS). In view of the results, low concentrations of TiO(2) of the order of tens of milligrams per liter were found to be insufficient for the degradation of the ECs in photoreactors with a short light-path length (29 cm). However, it was established that solar reactors of diameters of several hundreds of millimetres could be used for the efficient removal of ECs from WWTP effluents. The results presented show a general methodology for selecting the most efficient reactor diameter on the basis of the desired catalyst concentration. PMID:21943922

Prieto-Rodriguez, L; Miralles-Cuevas, S; Oller, I; Agüera, A; Li Puma, G; Malato, S

2012-04-15

291

Solar TiO2-assisted photocatalytic degradation of IGCC power station effluents using a Fresnel lens.  

PubMed

The heterogeneous TiO2 assisted photocatalytic degradation of wastewater from a thermoelectric power station under concentrated solar light irradiation using a Fresnel lens has been studied. The efficiency of photocatalytic degradation was determined from the analysis of cyanide and formate removal. Firstly, the influence of the initial concentration of H2O2 and TiO2 on the degradation kinetics of cyanides and formates was studied based on a factorial experimental design. Experimental kinetic constants were fitted using neural networks. Results showed that the photocatalytic process was effective for cyanides destruction (mainly following a molecular mechanism), whereas most of formates (degraded mainly via a radical path) remained unaffected. Finally, to improve formates degradation, the effect of lowering pH on their degradation rate was evaluated after complete cyanide destruction. The photooxidation efficiency of formates reaches a maximum at pH around 5-6. Above pH 6, formate anion is subjected to electrostatic repulsion with the negative surface of TiO2. At pH<4.5, formate adsorption and photon absorption are reduced due to some catalyst agglomeration. PMID:18078669

Monteagudo, J M; Durán, A; Guerra, J; García-Peña, F; Coca, P

2008-03-01

292

Europium Doped TiO(2) Hollow Nanoshells: Two-Photon Imaging of Cell Binding.  

PubMed

A simple scalable method to fabricate luminescent monodisperse 200 nm europium doped hollow TiO(2) nanoshell particles is reported. Fluorophore reporter, Eu(3+) 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 TiO(2) 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

Sandoval, Sergio; Yang, Jian; Alfaro, Jesus G; Liberman, Alexander; Makale, Milan; Chiang, Casey E; Schuller, Ivan K; Kummel, Andrew C; Trogler, William C

2012-11-13

293

Europium Doped TiO2 Hollow Nanoshells: Two-Photon Imaging of Cell Binding  

PubMed Central

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

Sandoval, Sergio; Yang, Jian; Alfaro, Jesus G.; Liberman, Alexander; Makale, Milan; Chiang, Casey E.; Schuller, Ivan K.

2012-01-01

294

Novel TiO2/PEGDA hybrid hydrogel prepared in situ on tumor cells for effective photodynamic therapy.  

PubMed

A novel inorganic/organic hybrid hydrogel system containing titanium dioxide (TiO2)/poly(ethylene glycol) double acrylates (PEGDA) was prepared by in situ photopolymerization on tumor cells for photodynamic therapy (PDT). TiO2 nanorods with diameter of ?5 nm and length of ?25 nm in this system presented dual functions, as effective photosensitizers for PDT and initiators for causing the in situ formation of hydrogel, under near-infrared (NIR) irradiation. The hybrid hydrogel retained the TiO2 around tumor cell to form a drug-loaded hydrogel shell. This resulted in a high concentration of singlet oxygen ((1)O2) under NIR irradiation, which induced apoptosis of tumor cell. Also, the hydrogel could reduce the side effects by preventing TiO2 from migrating to normal tissue. Furthermore, the TiO2 nanorods in this hydrogel shell were photochemically recyclable and could be reused in regular treatment. The outcomes of this study provide a new way to exploit multifunction of inorganic semiconductor nanomaterials for a variety of biomedical applications. PMID:24245666

Zhang, Hui; Shi, Ronghua; Xie, Anjian; Li, Juchuan; Chen, Long; Chen, Ping; Li, Shikuo; Huang, Fangzhi; Shen, Yuhua

2013-12-11

295

Inhibitor of differentiation 1 (Id1) expression attenuates the degree of TiO2-induced cytotoxicity in H1299 non-small cell lung cancer cells.  

PubMed

The inhibitor of differentiation (Id) family of genes, which encodes negative regulators of basic helix-loop-helix transcription factors, has been implicated in diverse cellular processes such as proliferation, apoptosis, differentiation, and migration. However, the specific role of Id1 in titanium dioxide (TiO2)-induced lung injury has not been investigated. In the present study, we investigated whether TiO2 induces apoptosis in H1299 lung cancer cells and by which pathways. Based on the results of the LDH assay, dual staining with Annexin V-FITC and propidium iodide (PI), and RT-PCR analysis of apoptosis-related gene expression, TiO2 caused a dose- and time-dependent decrease in cell viability and appeared to involve both necrosis and apoptosis. Furthermore, Id1 expression was significantly reduced in TiO2-treated cells compared with control cells. To further investigate the functional role of Id1, cells were transduced with a recombinant adenovirus expressing Id1, and the effects on sensitivity to TiO2 were analyzed. Id1 overexpression led to the enhancement of cellular proliferation and reduced the sensitivity of H1299 cells to TiO2. Our results indicate that Id1 expression attenuates the degree of TiO2-induced cytotoxicity in lung cells. PMID:19486931

Lee, Young Sook; Yoon, Seokjoo; Yoon, Hea Jin; Lee, Kyuhong; Yoon, Hyoun Kyoung; Lee, Jeung-Hoon; Song, Chang Woo

2009-09-28

296

Influence of TiO2 nanoparticles on cellular antioxidant defense and its involvement in genotoxicity in HepG2 cells  

NASA Astrophysics Data System (ADS)

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, gadd45? 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.

Petkovi?, Jana; Žegura, Bojana; Filipi?, Metka

2011-07-01

297

Semitransparent inverted polymer solar cells employing a sol-gel-derived TiO2 electron-selective layer on FTO and MoO3/Ag/MoO3 transparent electrode.  

PubMed

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

Li, Fumin; Chen, Chong; Tan, Furui; Li, Chunxi; Yue, Gentian; Shen, Liang; Zhang, Weifeng

2014-01-01

298

Semitransparent inverted polymer solar cells employing a sol-gel-derived TiO2 electron-selective layer on FTO and MoO3/Ag/MoO3 transparent electrode  

PubMed Central

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

2014-01-01

299

Nano Size Effects of TiO2 Nanotube Array on the Glioma Cells Behavior  

PubMed Central

In order to investigate the interplay between the cells and TiO2 nanotube array, and to explore the ability of cells to sense the size change in nano-environment, we reported on the behavior of glioma C6 cells on nanotube array coatings in terms of proliferation and apoptosis. The behavior of glioma C6 cells was obviously size-dependent on the coatings; the caliber with 15 nm diameter provided effective spacing to improve the cells proliferation and enhanced the cellular activities. C6 cells’ biological behaviors showed many similar tendencies to many phorocytes; the matching degree of geometry between nanotube and integrin defined that a spacing of 15 nm was optimal for inducing signals to nucleus, which results in achieving maximum activity of glioma cells. In addition, the immune behavior of cells was studied, a variety of inflammatory mediator’s gene expression levels were controlled by the nanoscale dimension, the expressions of IL-6 and IL-10 were higher on 30 nm than on 15 nm nanotube. PMID:23344031

Yang, He; Qin, Xiaofei; Tian, Ang; Zhang, Dongyong; Xue, Xiangxin; Wu, Anhua

2013-01-01

300

Cytotoxic, genotoxic and the hemolytic effect of titanium dioxide (TiO2 ) nanoparticles on human erythrocyte and lymphocyte cells in vitro.  

PubMed

With the increasing clinical use of titanium dioxide (TiO2 ) nanoparticles, a better understanding of their safety in the blood stream is required. The present study evaluates the toxic effect of commercially available TiO2 nanoparticles (~100 nm) using a battery of cytotoxic, genotoxic, hemolytic and morphological parameters. The cytotoxic effects of TiO2 nanoparticles in human lymphocyte cells were studied with respect to membrane damage, mitochondrial function, metabolic activity and lysosomal membrane stability. Genotoxicity in lymphocyte cells was quantitated using a comet assay. The mode of cell death (apoptosis/necrosis) was evaluated using PI/Annexin V staining. TiO2 nanoparticles were also evaluated for their hemolytic properties, osmotic fragility and interaction with hemoglobin. Human erythrocyte cells were studied for morphological alterations using atomic force microscopy (AFM). Results suggest that the particles could induce a significant reduction in mitochondrial dehydrogenase activity in human lymphocyte cells. Membrane integrity remained unaffected by nanoparticle treatment. DNA damage and apoptosis were induced by TiO2 nanoparticles in a dose-dependent manner. A study on human erythrocyte cells revealed a hemolytic property of TiO2 nanoparticles characterized by spherocytosis and echinocytosis. Spectral analysis revealed a hemoglobin TiO2 nanoparticle interaction. Our in vitro study results suggest that commercially available blood contacting nanoparticles (TiO2 nanoparticle) should be carefully evaluated for their toxic potential. PMID:23616399

Ghosh, Manosij; Chakraborty, Anirban; Mukherjee, Anita

2013-10-01

301

Solar Spectrum Photocatalytic Conversion of CO2 and Water Vapor Into Hydrocarbons Using TiO2 Nanoparticle Membranes  

NASA Astrophysics Data System (ADS)

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.

Rani, Sanju; Bao, Ningzhong; Roy, Somnath C.

2014-01-01

302

Synthesis of TiO2 nanotubes with ZnO nanoparticles to achieve antibacterial properties and stem cell compatibility  

NASA Astrophysics Data System (ADS)

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.

Liu, Wenwen; Su, Penglei; Chen, Su; Wang, Na; Ma, Yuanping; Liu, Yiran; Wang, Jinshu; Zhang, Zhenting; Li, Hongyi; Webster, Thomas J.

2014-07-01

303

Formation of TiO2 nanotubes via anodization and potential applications for photocatalysts, biomedical materials, and photoelectrochemical cell  

NASA Astrophysics Data System (ADS)

One-dimensional nanotube systems with high surface-to-volume ratios possess unique properties and are thus utilized in various applications. In this study, self-organized TiO2 nanotubes were prepared by anodization of a Ti foil in glycerol containing 5 wt% ammonium fluoride (NH4F) and 6 wt% ethylene glycol (EG). The surface morphology, average inner diameter, and average length of the nanotubes varied with the electrochemical anodization parameters. Nanotubes with uniform surface morphologies, an average diameter of 85 nm, and an average length of 1.1 ?m were obtained at 30 V for 1 h The as-prepared nanotubes were amorphous but they crystallized in the anatase phase after heating at about 400 °C for 2 h in an argon atmosphere. The photocatalytic activity of the TiO2 nanotubes was evaluated through the degradation of methyl orange (MO) and by investigating their bactericidal effect. Optimum photocatalysis of MO was achieved at a kinetic rate constant of 10-3 min-1. Furthermore, cell viability rapidly decreased on UV illumination and complete killing was achieved at 60 min in the presence of TiO2 nanotubes. For biomedical applications, the cellular activity on TiO2 nanotubes was determined using PA6 cells. Higher cellular activities were achieved using the anatase phase of 85-nm-diameter nanotubes than the amorphous phase. Photoelectrochemical hydrogen generation was investigated using nanotube photoanodes in 1 M potassium hydroxide (KOH) containing 1 wt% EG and xenon lamp. The maximum photocurrent density was 0.55 mA/cm2. These findings demonstrate that TiO2 nanotubes are promising for use in multifunctional applications.

Sreekantan, Srimala; Arifah Saharudin, Khairul; Wei, Lai Chin

2011-03-01

304

A facile approach for high surface area electrospun TiO2 nanostructures for photovoltaic and photocatalytic applications.  

PubMed

A rice-shaped TiO2-ZnO composite was prepared by electrospinning a mixture comprising the precursors of TiO2 and ZnO in polyvinyl acetate polymer dissolved in N,N-dimethyl acetamide. The electrospun nanofibers upon heat treatment in air resulted in collapse of the continuous fiber morphology and the formation of the rice-shaped TiO2-ZnO composite. The TiO2-ZnO composite was then treated with dilute acetic acid under hydrothermal conditions to etch ZnO from the TiO2-ZnO composite to get coral-shaped anisotropic TiO2. The structural anisotropy of TiO2 produced by the selective etching of ZnO resulted in a high surface area of 148 m(2) g(-1) for the TiO2. The initial and final materials were characterized by scanning electron microscopy, transmission electron microscopy, Raman and XPS spectroscopies, powder X-ray diffraction and BET surface area measurements. The utility of the anisotropic TiO2 in photovoltaics and photocatalysis was explored. Dye-sensitized solar cells fabricated using the TiO2 showed a conversion efficiency of 6.54% as against 4.8% for a control experiment with the rice-shaped TiO2. The anisotropic TiO2 also showed good photocatalysis in the degradation of methyl orange dye and phenol. PMID:24481057

Arun, T A; Madhavan, Asha Anish; Chacko, Daya K; Anjusree, G S; Deepak, T G; Thomas, Sara; Nair, Shantikumar V; Nair, A Sreekumaran

2014-03-28

305

Application of non-metal doped titania for inverted polymer solar cells  

NASA Astrophysics Data System (ADS)

Inverted bulk-heterojunction polymer solar cells have been fabricated applying non-metal doped TiO2 as electron extraction buffer layers. Spin-coated films from nitrogen, sulphur, and iodine doped TiO2 nanoparticles dispersed in dimethyl sulphoxide showed comparable roughness and uniformity as those from the pure TiO2 nanoparticles. The highest power conversion efficiency (PCE) of 1.67% was obtained for N-doped TiO2, whereas in the case of pure TiO2, PCE was around 1%. The highest short circuit current density (Jsc = 10.66 mA cm-2) was achieved for I-doped TiO2. Moreover, it was observed that devices with doped TiO2 exhibit better stability under constant illumination comparing to the control devices with pure TiO2.

Siuzdak, Katarzyna; Abbas, Mamatimin; Vignau, Laurence; Devynck, Mélanie; Dubacheva, Galina V.; Lisowska-Oleksiak, Anna

2012-12-01

306

Cell membrane integrity and internalization of ingested TiO(2) nanoparticles by digestive gland cells of a terrestrial isopod.  

PubMed

The present study was motivated by the paucity of reports on cellular internalization of ingested titanium dioxide (TiO(2)) nanoparticles (nano-TiO(2)). The model invertebrate (Porcellio scaber, Isopoda, Crustacea) was exposed to food dosed with nano-TiO(2) containing 100, 1,000, 3,000, or 5,000?µg nano-TiO(2) per gram of food. After 14?d of exposure, the amount of Ti in the entire body was analyzed by inductively coupled plasma-mass spectrometry, and elemental analyses of tissue cross sections were performed by particle induced X-ray emission. In addition, a series of toxicological markers including feeding parameters, weight change, and survival, as well as cytotoxic effects such as digestive gland cell membrane stability, were monitored. Internalization of ingested nano-TiO(2) by the isopod's digestive gland epithelial cells was shown to depend on cell membrane integrity. Cell membranes were found to be destabilized by TiO(2) particles, and at higher extracellular concentrations of nano-TiO(2), the nanoparticles were internalized. PMID:22447647

Novak, Sara; Drobne, Damjana; Valant, Janez; Pipan-Tkalec, Živa; Pelicon, Primož; Vavpeti?, Primož; Grlj, Nataša; Falnoga, Ingrid; Mazej, Darja; Remškar, Maja

2012-05-01

307

Phototoxicity of TiO2 nanoparticles under solar radiation to two aquatic species: Daphnia magna and Japanese medaka.  

PubMed

One target of development and application of TiO(2) nanoparticles (nano-TiO(2) ) is photochemical degradation of contaminants and photo-killing of microbes and fouling organisms. However, few ecotoxicological studies have focused on this aspect of nano-TiO(2) , specifically whether this photoreactivity might significantly increase hazard and risk of the materials in the natural environment. In the present study, we evaluated acute phototoxicity of nano-TiO(2) under simulated solar radiation (SSR) to two aquatic species-Daphnia magna and Japanese medaka, using 48-h and 96-h assays, respectively. A thorough characterization of the exposure system was performed by measuring particle agglomeration and TiO(2) concentration in suspension in a time-course manner. Sedimentation and loss of bulk concentration of nano-TiO(2) particles occurred at all concentrations above 2 mg/L and was more significant as concentration increased. Phototoxicity of nano-TiO(2) under SSR was enhanced by two to four orders of magnitude as compared to toxicity under ambient laboratory light, with a 48-h median lethal concentration (LC50) of 29.8 µg/L in D. magna and a 96-h LC50 of 2.2 mg/L in medaka. Our results also indicate that these effects are dependent on simultaneous exposure of the organisms to nanoparticles and SSR. This dramatic increase in toxicity of nano-TiO(2) at environmentally realistic levels of SSR indicates the need to incorporate this mode of action into risk assessment for nano-TiO(2) and other photoreactive nanomaterials. PMID:22544710

Ma, Hongbo; Brennan, Amanda; Diamond, Stephen A

2012-07-01

308

Distinctive toxicity of TiO2 rutile/anatase mixed phase nanoparticles on Caco-2 cells.  

PubMed

Titanium dioxide has a long-standing use as a food additive. Micrometric powders are, e.g., applied as whiteners in confectionary or dairy products. Possible hazards of ingested nanometric TiO(2) particles for humans and the potential influence of varying specific surface area (SSA) are currently under discussion. Five TiO(2)-samples were analyzed for purity, crystallinity, primary particle size, SSA, ? potential, and aggregation/agglomeration. Their potential to induce cytotoxicity, oxidative stress, and DNA damage was evaluated in human intestinal Caco-2 cells. Only anatase-rutile containing samples, in contrast to the pure anatase samples, induced significant LDH leakage or mild DNA damage (Fpg-comet assay). Evaluation of the metabolic competence of the cells (WST-1 assay) revealed a highly significant correlation between the SSA of the anatase samples and cytotoxicity. The anatase/rutile samples showed higher toxicity per unit surface area than the pure anatase powders. However, none of the samples affected cellular markers of oxidative stress. Our findings suggest that both SSA and crystallinity are critical determinants of TiO(2)-toxicity toward intestinal cells. PMID:22263745

Gerloff, Kirsten; Fenoglio, Ivana; Carella, Emanuele; Kolling, Julia; Albrecht, Catrin; Boots, Agnes W; Förster, Irmgard; Schins, Roel P F

2012-03-19

309

Improving the photoelectrochemical performance of polythiophene sensitized TiO 2 electrode by modification with gold nanoparticles  

Microsoft Academic Search

The nanocrystalline TiO2 electrode of polythiophene sensitized solar cell was modified by coating gold nanoparticles with thermal decomposition method. The surface concentration of polythiophene adsorbed on TiO2 electrode was increased obviously due to the participation of gold nanoparticles. The interfacial charge transfer kinetics were investigated by analyzing of photocurrent action spectrum of polythiophene sensitized TiO2 electrode and fluorescence spectrum of

Jinmao Chen; Yingping Zou; Yongfang Li; Xiaowen Zhou; Jingbo Zhang; Xueping Li; Xurui Xiao; Yuan Lin

2008-01-01

310

Fabrication of dye-sensitized solar cells by spray pyrolysis deposition (SPD) technique  

Microsoft Academic Search

Porous TiO2 films were successfully synthesized in air from a commercial TiO2-sol by spray pyrolysis deposition (SPD) technique. The film consisted of fine TiO2 particles, approximately 30–50nm in size, and showed the roughness factor as high as 1000. A dye-sensitized solar cell was constructed by SPD technique. In this technique, porous TiO2\\/dense TiO2\\/SnO2:F junction was prepared within 10–15min, which drastically

Masayuki Okuya; Koji Nakade; Daisuke Osa; Takafumi Nakano; G. R Asoka Kumara; Shoji Kaneko

2004-01-01

311

Bandgap tailoring of in-situ nitrogen-doped TiO2 sputtered films intended for electrophotocatalytic applications under solar light  

NASA Astrophysics Data System (ADS)

We report on a reactive RF-sputtering process permitting the in-situ nitrogen doping of TiO2 films in order to shift their photoactivity from UV to visible range. By carefully controlling the relative nitrogen-to-argon mass flow rate ratio (within the 0%-25% range) in the sputter deposition chamber, TiO2:N films were grown with nitrogen contents ranging from 0 to 6.2 at. %, as determined by high-resolution X-ray spectroscopy measurements. A systematic investigation of the crystalline structure of the TiO2:N films, as a function of their N content, revealed that low N contents (0.2-0.3 at. %) induce crystallization in the rutile phase while higher N contents (?1.4 at. %) were accompanied with the recovery of the anatase structure with an average crystallite size of ˜35 nm. By using both UV-Vis absorption and spectroscopic ellipsometry measurements, we were able to quantitatively determine the bandgap (Eg) variation of the TiO2:N films as a function of their N content. Thus, we have demonstrated that the Eg of the TiO2:N films effectively narrows from 3.2 eV down to a value as low as ˜2.3 eV for the optimal N doping concentration of 3.4 at. % (higher N incorporation does not translate into further red shifting of the TiO2:N films' Eg). The photoactivity of the TiO2:N films under visible light was confirmed through electro-photocatalytic decomposition of chlortetracycline (CTC, an emerging water pollutant) under standard 1.5AM solar radiation. Thus, CTC degradation efficiencies of up to 98% were achieved with 2 hours process cycles under simulated solar light. Moreover, the electro-photocatalytic performance of the TiO2:N films is shown to be directly correlated to their optoelectronic properties (namely their bandgap narrowing).

Delegan, N.; Daghrir, R.; Drogui, P.; El Khakani, M. A.

2014-10-01

312

Effect of nanostructured TiO2 crystal phase on photoinduced apoptosis of breast cancer epithelial cells  

PubMed Central

Purpose The use of nanoparticles has seen exponential growth in the area of health care, due to the unique physicochemical properties of nanomaterials that make them desirable for medical applications. The aim of this study was to examine the effects of crystal phase-nanostructured titanium dioxide particles on bioactivity/cytotoxicity in breast cancer epithelial cells. Materials and methods Cultured Michigan Cancer Foundation (MCF)-7 and human breast adenocarcinoma (MDA-MB-468) breast cancer epithelial cells were exposed to ultraviolet A light (wavelength 350 nm) for 20 minutes in the presence of aqueous dispersions of two different nanostructured titanium dioxide (TiO2) crystal phases: anatase and an anatase–rutile mixture. Detailed characterization of each titanium dispersion was performed by dynamic light scattering. A 3-(4,5-dimethylthiazol-2-yl)-2,5 diphenyltetrazolium bromide (MTT) colorimetric assay was employed to estimate the percentage of viable cells after each treatment. Western blot analysis of protein expression and characterization, as well as a deoxyribonucleic acid (DNA)-laddering assay, were used to detect cell apoptosis. Results Our results documented that 100% anatase TiO2 nanoparticles (110–130 nm) exhibited significantly higher cytotoxicity in the highly malignant MDA-MB-468 cancer cells than anatase– rutile mixtures (75%/25%) with the same size. On the contrary, MCF-7 cells (characterized by low invasive properties) were not considerably affected. Exposure of MDA-MB-468 cells to pure anatase nanoparticles or anatase–rutile mixtures for 48 hours resulted in increased proapoptotic Bax expression, caspase-mediated poly(adenosine diphosphate ribose) polymerase (PARP) cleavage, DNA fragmentation, and programmed cell death/apoptosis. Conclusion The obtained results indicated that pure anatase TiO2 nanoparticles exhibit superior cytotoxic effects compared to anatase–rutile mixtures of the same size. The molecular mechanism of TiO2 nanoparticle cytotoxicity involved increased Bax expression and caspase-mediated PARP inactivation, thus resulting in DNA fragmentation and cell apoptosis. PMID:25061298

Lagopati, Nefeli; Tsilibary, Effie-Photini; Falaras, Polycarpos; Papazafiri, Panagiota; Pavlatou, Evangelia A; Kotsopoulou, Eleni; Kitsiou, Paraskevi

2014-01-01

313

Crystal structure mediates mode of cell death in TiO 2 nanotoxicity  

Microsoft Academic Search

Certain properties that nanoparticles possess differentiate them from their bulk counterparts, and these characteristics must\\u000a be evaluated prior to nanoparticle studies and include: size, shape, dispersion, physical and chemical properties, surface\\u000a area, and surface chemistry. Early nanotoxicity studies evaluating TiO2 have yielded conflicting data which identify either size or crystal structure as the mediating property for nano-TiO2 toxicity. However, it

Laura K. Braydich-Stolle; Nicole M. Schaeublin; Richard C. Murdock; Jingkun Jiang; Pratim Biswas; John J. Schlager; Saber M. Hussain

2009-01-01

314

Photocatalytic activity of sea water using TiO 2 catalyst under solar light  

Microsoft Academic Search

Wastewater is generally released into the rivers and streams in developing countries. Industrial wastewater usually contains highly toxic pollutants, cyanides, chlorinated compounds. Ultraviolet (UV) radiation from sunlight also decomposes organic compounds by oxidation process. However, the process is less effective due to large amount of toxic effluent entering in the main stream of water. The solar radiation can effectively be

S. S. Shinde; C. H. Bhosale; K. Y. Rajpure

2011-01-01

315

Diatom-templated TiO2 with enhanced photocatalytic activity: biomimetics of photonic crystals  

NASA Astrophysics Data System (ADS)

The siliceous frustules with sophisticated optical structure endow diatoms with superior solar light-harvesting abilities for effective photosynthesis. The preserved frustules of diatom ( Cocconeis placentula) cells, as biophotonic crystals, were thus employed as both hard templates and silicon resources to synthesize TiO2 photocatalyst. Characterizations by a combination of physicochemical techniques proved that the bio-inspired sample is TiO2-coated SiO2 with biogenic C self-doped in. It was found that the synthesized composites exhibited similar morphologies to the original diatom templates. In comparison with commercial Degussa P25 TiO2, the C-doped TiO2/SiO2 catalyst exhibited more light absorption in the visible region and higher photocatalytic efficiency for photodegradation of rhodamine B under visible light due to the biomorphic hierarchical structures, TiO2 coating and C-doping.

He, Jiao; Chen, Daomei; Li, Yongli; Shao, Junlong; Xie, Jiao; Sun, Yuejuan; Yan, Zhiying; Wang, Jiaqiang

2013-11-01

316

High-performance method for specific effect on nucleic acids in cells using TiO2~DNA nanocomposites  

NASA Astrophysics Data System (ADS)

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 ?g/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 ?g/ml (30 nM for DNA), so its selectivity index was calculated as ~1200. Thus, the proposed nanocomposites are prospective for therapeutic application.

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

317

High-performance method for specific effect on nucleic acids in cells using TiO2~DNA nanocomposites.  

PubMed

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 TiO(2)·PL-DNA nanocomposites (polylysine-containing DNA fragments noncovalently immobilized onto TiO(2) 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 (TC(50) ? 1800 ?g/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. IC(50) for nanocomposites was estimated to be 1.5 ?g/ml (30 nM for DNA), so its selectivity index was calculated as ~1200. Thus, the proposed nanocomposites are prospective for therapeutic application. PMID:23091696

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

2012-01-01

318

Nb doped TiO2 as a Cathode Catalyst Support Material for Polymer Electrolyte Membrane Fuel Cells  

NASA Astrophysics Data System (ADS)

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.

O'Toole, Alexander W.

319

Dye-Sensitized Solar Cells with Conversion Efficiency of 11.1%  

Microsoft Academic Search

Dye-sensitized solar cells (DSCs) using titanium dioxide (TiO2) electrodes with different haze were investigated. It was found that the incident photon to current efficiency (\\\\mathit{IPCE}) of DSCs increases with increase in the haze of the TiO2 electrodes, especially in the near infrared wavelength region. Conversion efficiency of 11.1%, measured by a public test center, was achieved using high haze TiO2

Yasuo Chiba; Ashraful Islam; Yuki Watanabe; Ryoichi Komiya; Naoki Koide; Liyuan Han

2006-01-01

320

The role of conducting-oxide-substrate type and morphology in TiO 2 films grown by microwave chemical bath deposition (MW-CBD) and their photovoltaic characteristics  

Microsoft Academic Search

MW-CBD is a low-temperature deposition technique that gives transparent and well-adhered TiO2 thin films. TiO2 films on transparent conducting oxide are important for dye-sensitized solar cells, extremely thin absorber solar cells and for electrochromic devices. We study how the growth process of TiO2 films using MW-CBD is influenced by substrate type using SnO2:F and ITO substrates. Crystallinity of the films

Elena Vigil; Bernardo González; Inti Zumeta; Ana M Peiró; Concepción Domingo; Xavier Domènech; José A Ayllón

2004-01-01

321

Electrospinning processed nanofibrous TiO2 membranes for photovoltaic applications  

NASA Astrophysics Data System (ADS)

We have recently fabricated dye-sensitized solar cells (DSSCs) comprising nanofibrous TiO2 membranes as electrode materials. A thin TiO2 film was pre-deposited on fluorine doped tin oxide (FTO) coated conducting glass substrate by immersion in TiF4 aqueous solution to reduce the electron back-transfer from FTO to the electrolyte. The composite polyvinyl acetate (PVac)/titania nanofibrous membranes can be deposited on the pre-deposited thin TiO2 film coated FTO by electrospinning of a mixture of PVac and titanium isopropoxide in N,N-dimethylformamide (DMF). The nanofibrous TiO2 membranes were obtained by calcining the electrospun composite nanofibres of PVac/titania as the precursor. Spectral sensitization of the nanofibrous TiO2 membranes was carried out with a ruthenium (II) complex, cis-dithiocyanate-N,N'-bis(2,2'-bipyridyl-4,4'-dicarboxylic acid) ruthenium (II) dihydrate. The results indicated that the photocurrent and conversion efficiency of electrodes can be increased with the addition of the pre-deposited TiO2 film and the adhesion treatment using DMF. Additionally, the dye loading, photocurrent, and efficiency of the electrodes were gradually increased by increasing the average thickness of the nanofibrous TiO2 membranes. The efficiency of the fibrous TiO2 photoelectrode with the average membrane thickness of 3.9 µm has a maximum value of 4.14%.

Onozuka, Katsuhiro; Ding, Bin; Tsuge, Yosuke; Naka, Takayuki; Yamazaki, Michiyo; Sugi, Shinichiro; Ohno, Shingo; Yoshikawa, Masato; Shiratori, Seimei

2006-02-01

322

High open circuit voltages of solar cells based on quantum dot and dye hybrid-sensitization  

NASA Astrophysics Data System (ADS)

A type of solar cell based on quantum dot (QD) and dye hybrid-sensitized mesoporous TiO2 film electrode was designed and reported. The electrode was consisted of a TiO2 nanoparticle (NP) thin film layer sensitized with CdS quantum dot (QD) and an amorphous TiO2 coated TiO2 NP thin film layer that sensitized with C106 dye. The amorphous TiO2 layer was obtained by TiCl4 post-treatment to improve the properties of solar cells. Research showed that the solar cells fabricated with as-prepared hybrid-sensitized electrode exhibited excellent photovoltaic performances and a fairly high open circuit voltage of 796 mV was achieved.

Zhao, Yujie; Bala, Hari; Zhao, Wanyu; Chen, Jingkuo; Li, Huayang; Fu, Wuyou; Sun, Guang; Cao, Jianliang; Zhang, Zhanying

2014-01-01

323

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 ...

324

Improving cytocompatibility of Co28Cr6Mo by TiO2 coating: gene expression study in human endothelial cells  

PubMed Central

Cobalt-based materials are widely used for coronary stents, as well as bone and joint implants. However, their use is associated with high corrosion incidence. Titanium alloys, by contrast, are more biocompatible owing to the formation of a relatively inactive titanium oxide (TiO2) layer on their surface. This study was aimed at improving Co28Cr6Mo alloy cytocompatibility via sol–gel TiO2 coating to reduce metal corrosion and metal ion release. Owing to their role in inflammation and tissue remodelling around an implant, endothelial cells present a suitable in vitro model for testing the biological response to metallic materials. Primary human endothelial cells seeded on Co28Cr6Mo showed a stress phenotype with numerous F-actin fibres absent on TiO2-coated material. To investigate this effect at the gene expression level, cDNA microarray analysis of in total 1301 genes was performed. Compared with control cells, 247 genes were expressed differentially in the cells grown on Co28Cr6Mo, among them genes involved in proliferation, oxidative stress response and inflammation. TiO2 coating reduced the effects of Co28Cr6Mo on gene expression in endothelial cells, with only 34 genes being differentially expressed. Quantitative real-time polymerase chain reaction and protein analysis confirmed microarray data for selected genes. The effect of TiO2 coating can be, in part, attributed to the reduced release of Co2+, because addition of CoCl2 resulted in similar cellular responses. TiO2 coating of cobalt-based materials, therefore, could be used in the production of cobalt-based devices for cardiovascular and skeletal applications to reduce the adverse effects of metal corrosion products and to improve the response of endothelial and other cell types. PMID:23825117

Tsaryk, R.; Peters, K.; Unger, R. E.; Feldmann, M.; Hoffmann, B.; Heidenau, F.; Kirkpatrick, C. J.

2013-01-01

325

TiO2-doped phosphate glass microcarriers: A stable bioactive substrate for expansion of adherent mammalian cells  

PubMed Central

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

Guedes, Joana C; Park, Jeong-Hui; Lakhkar, Nilay J; Kim, Hae-Won; Knowles, Jonathan C

2013-01-01

326

Intestinal toxicity evaluation of TiO2 degraded surface-treated nanoparticles: a combined physico-chemical and toxicogenomics approach in caco-2 cells  

PubMed Central

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??g/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??g/ mL, which is much higher than potential environmental concentrations. Conclusions TiO2 STNPs, degraded or not, are not harmful to Caco-2 cells and are unlikely to penetrate the body via oral route. It is likely that the strong persistence of the aluminium hydroxide layer surrounding these nanoparticles protects the cells from a direct contact with the potentially phototoxic TiO2 core. PMID:22650444

2012-01-01

327

Dual effects and mechanism of TiO2 nanotube arrays in reducing bacterial colonization and enhancing C3H10T1/2 cell adhesion  

PubMed Central

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

Peng, Zhaoxiang; Ni, Jiahua; Zheng, Kang; Shen, Yandong; Wang, Xiaoqing; He, Guo; Jin, Sungho; Tang, Tingting

2013-01-01

328

Achieving enhanced DSSC performance by microwave plasma incorporation of carbon into TiO2 photoelectrodes  

NASA Astrophysics Data System (ADS)

The photoactivity of carbon-incorporated titanium dioxide (TiO2) has been widely reported. This study involves a novel approach to the incorporation of carbon into TiO2 through the use of microwave plasma processing. The process involved thermally treating printed TiO2 nanoparticle coatings in a microwave-induced argon-oxygen plasma containing low concentrations of methane. The resulting deposited carbon layer was characterized using XRD, XPS, Raman, UV-vis, ellipsometry, and optical profilometry. It was found that the methane gas was dissociated in the microwave plasma into its carbon species, which were then deposited as a nm-thick layer onto the TiO2 coatings, most likely in the form of graphite. The photovoltaic performances of both the TiO2 and the carbon-incorporated TiO2 were assessed through J-V and IPCE measurements of the N719-sensitized solar cells using the titania as their photoanodes. Up to a 72% improvement in the maximum power density (Pd-max) was observed for the carbon-incorporated TiO2 samples as compared to the TiO2, onto which no carbon was added. This improvement was found to be mainly associated with an increase in the short-circuit current density (Jsc), but independent from the open-circuit voltage (Voc), the filter factor (FF), and the level of dye adsorption. Possible contributory factors to the improved performance of the carbon-incorporated TiO2 were the enhanced electron conductivity and electron lifetime, both of which were elucidated through electrochemical impedance spectroscopy (EIS). When the surface layer was examined using XPS, the optimal carbon content on the TiO2 coating surface was found to be 8.4%, beyond which there was a reduction in the DSSC efficiency.

Dang, Binh H. Q.; MacElroy, Don; Dowling, Denis P.

2013-06-01

329

Variation of cell spreading on TiO2 film modified by 775 nm and 388 nm femtosecond laser irradiation  

NASA Astrophysics Data System (ADS)

Titanium (Ti) is one of the most used biomaterials in metals. However, Ti is typically artificial materials. Thus, it is necessary for improving the biocompatibility of Ti. Recently, coating of the titanium dioxides (TiO2) film on Ti plate has been proposed to improve biocompatibility of Ti. We have developed coating method of the film on Ti plate with an aerosol beam. Periodic structures formation on biomaterials was also a useful method for improving the biocompatibility. Direction of cell spreading might be controlled along the grooves of periodic microstructures. In our previous study, periodic nanostructures were formed on the film by femtosecond laser irradiation at fundamental wave (775 nm). Period of the periodic nanostructures was about 230 nm. In cell test, cell spreading along the grooves of the periodic nanostructures was observed although it was not done for the film without the periodic nanostructures. Then, influence of the period of the periodic nanostructures on cell spreading has not been investigated yet. The period might be changed by changing the laser wavelength. In this study, the periodic nanostructures were created on the film with femtosecond laser at 775nm and 388 nm, respectively. After cell test, cell spreading along the grooves of the periodic nanostructures was observed on 775 nm and 388nm laser irradiated areas. Distribution of direction of cell spreading on laser irradiated area was also examined. These results suggested that controlling the cell spreading on periodic nanostructures with period of 230 nm was better than that with period of 130 nm.

Tsukamoto, M.; Shinonaga, T.; Sato, Y.; Chen, P.; Nagai, A.; Hanawa, T.

2014-03-01

330

Physico-chemical characteristics and cyto-genotoxic potential of ZnO and TiO2 nanoparticles on human colon carcinoma cells  

NASA Astrophysics Data System (ADS)

The aim of the present study is to investigate the role of the physico-chemical properties of ZnO and TiO2 NPs in the potential cytotoxicity, genotoxicity and oxidative DNA damage induction on Caco-2 cell line. As negative control, fine TiO2 particles were used. The characterization of particles was carried out by electron microscopy (SEM, TEM) using a Soft Imaging System. To evaluate the effects of ZnO and TiO2 NPs induced on Caco-2 viability, Neutral Red assay was performed after treatment with different particle concentrations. Our results showed a significant dose and time dependent effect after treatment with ZnO NPs. On the contrary, no effect was observed on Caco-2 cells exposed to TiO2 particles either in micro-and in nano-size. The role of surface in the cytotoxicity induced on Caco-2 was also considered. The levels of DNA 8-oxodG, as the main marker of oxidative DNA damage, were measured by high-performance liquid chromatography with electrochemical detection (HPLC/EC). A significant increase in the 8-oxodG levels was observed after 6 h exposure for both NPs. The estimation of the potential genotoxicity of the two NPs is ongoing by the cytokinesis-block micronucleus assay. Our preliminary results showed that a slight micronucleus increase in binucleated cells was detected in the dose range applied only for ZnO.

Barone, F.; De Berardis, B.; Bizzarri, L.; Degan, P.; Andreoli, C.; Zijno, A.; De Angelis, I.

2011-07-01

331

Controlling Surface Defects and Photophysics in TiO2 Nanoparticles.  

PubMed

Titanium dioxide (TiO2) is widely used for photocatalysis and solar cell applications, and the electronic structure of bulk TiO2 is well understood. However, the surface structure of nanoparticulate TiO2, which has a key role in properties such as solubility and catalytic activity, still remains controversial. Detailed understanding of surface defect structures may help explain reactivity and overall materials performance in a wide range of applications. In this work we address the solubility problem and surface defects control on TiO2 nanoparticles. We report the synthesis and characterization of ?4 nm TiO2 anatase spherical nanoparticles that are soluble and stable in a wide range of organic solvents and water. By controlling the temperature during the synthesis, we are able to tailor the density of defect states on the surface of the TiO2 nanoparticles without affecting parameters such as size, shape, core crystallinity, and solubility. The morphology of both kinds of nanoparticles was determined by TEM. EPR experiments were used to characterize the surface defects, and transient absorption measurements demonstrate the influence of the TiO2 defect states on photoinduced electron transfer dynamics. PMID:25109403

Llansola-Portoles, Manuel J; Bergkamp, Jesse J; Finkelstein-Shapiro, Daniel; Sherman, Benjamin D; Kodis, Gerdenis; Dimitrijevic, Nada M; Gust, Devens; Moore, Thomas A; Moore, Ana L

2014-11-13

332

Controllable atomic layer deposition of one-dimensional nanotubular TiO2  

NASA Astrophysics Data System (ADS)

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.

Meng, Xiangbo; Banis, Mohammad Norouzi; Geng, Dongsheng; Li, Xifei; Zhang, Yong; Li, Ruying; Abou-Rachid, Hakima; Sun, Xueliang

2013-02-01

333

Fabrication and characterization of core/shell structured TiO2/polyaniline nanocomposite.  

PubMed

A novel core/shell structured TiO(2)/polyaniline nanocomposite was fabricated by grafting aniline on aminobenzoate monolayer that is chemically adsorbed on the TiO(2) nanocrystal surface. The formation and nanostructure of the nanocomposite were investigated by FT-IR and UV-Vis spectra, TEM, FE-SEM, and TG-DTA analysis. Adsorption of aminobenzoate on the TiO(2) surface is an effective method to obtain the uniform nanocomposite. The thickness of polyaniline layer coating on the TiO(2) nanocrystal surface can be controlled in a range of 2-5 nm by this method. A photoelectrochemical study was carried out on the TiO(2)/polyaniline nanocomposite, and found that polyaniline in the nanocomposite acted as a visible-light sensitizer in a photoelectrochemical reaction. The sensitization effect increased with increasing binding strength between polyaniline and TiO(2). A dye-sensitized solar cell with a short circuit current density of 0.19 mA/cm(2) and an open circuit voltage of 0.35 V was fabricated by using the TiO(2)/polyaniline nanocomposite film as a sensitized electrode. PMID:21329938

Yang, Sitao; Ishikawa, Yoshie; Itoh, Hiroshi; Feng, Qi

2011-04-15

334

Direction-dependent Intermolecular Interactions: Catechol on TiO2(110)-11  

E-print Network

is often used in solar energy conversion, where the material is adopted as the electrode in dye step edges is observed at room temperature. A statistical analysis of intermolecular distances-sensitized solar cells. [3-5] The band gap of TiO2 is ~3.2eV, located in the ultraviolet region. A monolayer

Diebold, Ulrike

335

Nanocoral architecture of TiO 2 by hydrothermal process: Synthesis and characterization  

NASA Astrophysics Data System (ADS)

TiO2 thin films with novel nanocoral-like morphology were successfully grown directly onto the glass and conducting fluorine doped tin oxide coated glass substrates via multi-step hydrothermal (MSH) process. Titanium chloroalkoxide [TiCl2 (OEt)2 (HOEt)2)] precursor was used in an aqueous saturated NaCl in presence of 1 mM HCl catalyst and HNO3 peptizer at 120 °C. Reaction time varied from 3 to 12 h. The morphological features and physical properties of TiO2 films were investigated by field emission scanning electron microscopy, high resolution transmission electron microscopy, X-ray diffraction, Fourier transform IR spectroscopy, Fourier transform Raman spectroscopy, room temperature photoluminescence spectroscopy and X-ray photoelectron spectroscopy. The surface morphology revealed the formation of TiO2 corals having nanosized (30-40 nm) polyps. The photoelectrochemical properties of the TiO2 nanocoral electrodes were investigated in 0.1 M NaOH electrolyte under UV illumination. The results presented in this study highlight two major findings: (i) ability to tune the photoelectrochemical response and photoconversion efficiency via controlled thickness of TiO2 nanocorals and (ii) the substantial increase in short circuit photocurrent (Jsc) due to the improved charge transport through TiO2 nanocorals prepared via MSH process. This approach would be quite useful for the fabrication of nanocoral architecture that finds key applications in photocatalysis, dye-sensitized solar cells and hybrid solar cells.

Mali, Sawanta S.; Shinde, Pravin S.; Betty, C. A.; Bhosale, Popatrao N.; Lee, Won J.; Patil, Pramod S.

2011-09-01

336

Degradation of glyphosate in soil photocatalyzed by Fe3O4/SiO2/TiO2 under solar light.  

PubMed

In this study, Fe(3)O(4)/SiO(2)/TiO(2) photocatalyst was prepared via a sol-gel method, and Fe(3)O(4) particles were used as the core of the colloid. Diffraction peaks of Fe(3)O(4) crystals are not found by XRD characterization, indicating that Fe(3)O(4) particles are well encapsulated by SiO(2). FTIR characterization shows that diffraction peaks of Ti-O-Si chemical bonds become obvious when the Fe(3)O(4) loading is more than 0.5%. SEM characterization indicates that agglomeration occurs in the Fe(3)O(4)/SiO(2)/TiO(2) photocatalyst, whereas photocatalysts modified by Fe(3)O(4)/SiO(2) present excellent visible light absorption performance and photocatalytic activity, especially when the Fe(3)O(4) loading is 0.5%. Photocatalytic degradation of glyphosate in soil by these photocatalysts under solar irradiation was investigated. Results show that 0.5% Fe(3)O(4)/SiO(2)/TiO(2) has the best photocatalytic activity. The best moisture content of soil is 30%~50%. Degradation efficiency of glyphosate reaches 89% in 2 h when the dosage of photocatalyst is 0.4 g/100 g (soil), and it increased slowly when more photocatalyst was used. Soil thickness is a very important factor for the photocatalytic rate. The thinner the soil is, the better the glyphosate degradation is. Degradation of glyphosate is not obviously affected by sunlight intensity when the intensity is below 6 mW/cm(2) or above 10 mW/cm(2), but it is accelerated significantly when the sunlight intensity increases from 6 mW/cm(2) to 10 mW/cm(2). PMID:21695039

Xu, Xuan; Ji, Fangying; Fan, Zihong; He, Li

2011-04-01

337

A novel 3D structure composed of strings of hierarchical TiO2 spheres formed on TiO2 nanobelts with high photocatalytic properties  

NASA Astrophysics Data System (ADS)

A novel hierarchical titanium dioxide (TiO2) composite nanostructure with strings of anatase TiO2 hierarchical micro-spheres and rutile nanobelts framework (TiO2 HSN) is successfully synthesized via a one-step hydrothermal method. Particularly, the strings of hierarchical spheres are assembled by very thin TiO2 nanosheets, which are composed of highly crystallized anatase nanocrystals. Meanwhile, the HSN has a large surface area of 191 m2/g, which is about 3 times larger than Degussa P25. More importantly, the photocatalytic activity of HSN and P25 were evaluated by the photocatalytic oxidation decomposition of methyl orange (MO) under UV light illumination, and the TiO2 HSN shows enhanced photocatalytic activity compared with Degussa P25, as result of its continuous hierarchical structures, special conductive channel and large specific surface area. With these features, the hierarchical TiO2 may have more potential applications in the fields of dye-sensitized solar cells and lithium ion batteries.

Jiang, Yongjian; Li, Meicheng; Song, Dandan; Li, Xiaodan; Yu, Yue

2014-03-01

338

Evaluations of the TiO2/simulated solar UV degradations of XAD fractions of natural organic matter from a bog lake using size-exclusion chromatography.  

PubMed

This work reports on the changes in compositions of humic acids (HAs) and fulvic acids (FAs) during photocatalytic degradation. The HAs and FAs were obtained from the XAD-resin fractionation of natural-organic matter (NOM) from a bog lake (Lake Hohloh, Black Forest, Germany). Degussa P-25 titanium dioxide (TiO2) in a suspension and a solar UV simulator (batch reactor) were used in the experiments. The photocatalytic degradation of the HAs and FAs were monitored using size-exclusion chromatography (SEC) equipped with dissolved organic carbon (DOC) and ultraviolet (UV254) detection (SEC-DOC and SEC-UV254) and UV-Vis spectrophotometry. The evolutions of the photocatalytic degradations of the HA and FA fractions were selective. The photocatalytic degradation started with the degradations of high molecular weight compounds with relatively high UV254 absorbances in the HA and FA fractions to yield low molecular weight compounds showing less specific UV254 absorbances. Observance of the same tendency for the original NOM from Lake Hohloh indicates that these XAD-fractions still having complex compound mixtures. However, the larger molecular weight fractions of the FAs showed higher preferential adsorptions onto TiO2, which caused their faster degradation rates. Furthermore, FAs showed a greater reduction of the total THM formation potential (TTHMFP) and the organic halogen compounds adsorbable on activated carbon formation potential (AOXFP), in comparison with the HAs. PMID:23863374

Valencia, Sergio; Marín, Juan M; Restrepo, Gloria; Frimmel, Fritz H

2013-09-15

339

Use of titanium dioxide nanoparticles biosynthesized by Bacillus mycoides in quantum dot sensitized solar cells  

PubMed Central

Background One of the major challenges of nanotechnology during the last decade has been the development of new procedures to synthesize nanoparticles. In this context, biosynthetic methods have taken hold since they are simple, safe and eco-friendly. Results In this study, we report the biosynthesis of TiO2 nanoparticles by an environmental isolate of Bacillus mycoides, a poorly described Gram-positive bacterium able to form colonies with novel morphologies. This isolate was able to produce TiO2 nanoparticles at 37°C in the presence of titanyl hydroxide. Biosynthesized nanoparticles have anatase polymorphic structure, spherical morphology, polydisperse size (40–60 nm) and an organic shell as determined by UV–vis spectroscopy, TEM, DLS and FTIR, respectively. Also, conversely to chemically produced nanoparticles, biosynthesized TiO2 do not display phototoxicity. In order to design less expensive and greener solar cells, biosynthesized nanoparticles were evaluated in Quantum Dot Sensitized Solar Cells (QDSSCs) and compared with chemically produced TiO2 nanoparticles. Solar cell parameters such as short circuit current density (ISC) and open circuit voltage (VOC) revealed that biosynthesized TiO2 nanoparticles can mobilize electrons in QDSSCs similarly than chemically produced TiO2. Conclusions Our results indicate that bacterial extracellular production of TiO2 nanoparticles at low temperatures represents a novel alternative for the construction of green solar cells. PMID:25027643

2014-01-01

340

Enhanced photoelectrochemical performance by synthesizing CdS decorated reduced TiO2 nanotube arrays.  

PubMed

The efficient utilization of solar spectrum and photo-induced charge transport are critical aspects in improving the light conversion efficiency of solar cells and hydrogen generation. In this work, reduced TiO2 nanotube arrays with CdS decoration were fabricated through the simple cathodic polarization of annealed TiO2 nanotube arrays followed by the chemical deposition of CdS nanoparticles. Scanning electron microscopy (SEM), X-ray diffraction (XRD) and Raman spectroscopy confirmed the successful fabrication of the target material. UV-visible diffuse reflectance spectra showed a Burstein-Moss shift for reduced TiO2 NTs and a red shift of the absorption edge towards ca. 563 nm for CdS-decorated R-TiO2 NTs. Cyclic voltammetry and impedance spectra together demonstrate the decreased charge transport resistance for reduced TiO2 NTs. Under the excitation of monochromatic light at 420 nm, the proposed CdS-decorated reduced TiO2 NTs exhibit the maximum IPCE value of 30.12% in 1 M Na2SO3 electrolyte, which is almost twice higher than that achieved on CdS-decorated pristine TiO2 NTs. Therefore, the results here highlight the significance of charge transport in the light conversion process. The enhanced charge transport properties are ascribed to the increased number of electrons, which is brought about by the lattice oxygen vacancies (Ti(3+)) during the cathodic polarization. PMID:25265452

Zhang, Qian; Wang, Ling; Feng, Jiangtao; Xu, Hao; Yan, Wei

2014-10-01

341

Recent progress in design, synthesis, and applications of one-dimensional TiO2 nanostructured surface heterostructures: a review.  

PubMed

One-dimensional TiO2 nanostructured surface heterostructures (1D TiO2NSHs) have been comprehensively studied during the past two decades because of the possible practical applications in various fields, including photocatalysis, dye-sensitized solar cells, sensors, lithium batteries, biomedicine, catalysis, and supercapacitors. Combining extensive advancements in materials science and nanotechnology, a 1D TiO2NSH material with well-controlled size, morphology, and composition has been designed and synthesized. More importantly, its superior properties, including a high aspect ratio structure, chemical stability, large specific surface area, excellent electronic or ionic charge transfer, and a specific interface effect, have attracted a great deal of interest in improving current performance and exploring new applications. In this tutorial review, we introduce the characteristics of 1D TiO2 nanostructures, the design principles for the fabrication of 1D TiO2NSHs, and we also summarize the recent progress in developing synthesis methods and applications of 1D TiO2NSHs in different fields. The relationship between the secondary phase and the 1D TiO2 nanostructure and between the performance in applications and the excellent physical properties of 1D TiO2NSHs are also discussed. PMID:25014328

Tian, Jian; Zhao, Zhenhuan; Kumar, Anil; Boughton, Robert I; Liu, Hong

2014-10-21

342

Improving the photoelectrochemical performance of polythiophene sensitized TiO 2 electrode by modification with gold nanoparticles  

NASA Astrophysics Data System (ADS)

The nanocrystalline TiO 2 electrode of polythiophene sensitized solar cell was modified by coating gold nanoparticles with thermal decomposition method. The surface concentration of polythiophene adsorbed on TiO 2 electrode was increased obviously due to the participation of gold nanoparticles. The interfacial charge transfer kinetics were investigated by analyzing of photocurrent action spectrum of polythiophene sensitized TiO 2 electrode and fluorescence spectrum of polythiophene solution in the presence of TiO 2 nanocrystals. After modification with Au nanoparticles, short circuit current of polythiophene sensitized solar cell increased from 2.68 mA cm -2 to 3.92 mA cm -2 and power conversion efficiency from 0.88% to 1.30% at AM 1.5.

Chen, Jinmao; Zou, Yingping; Li, Yongfang; Zhou, Xiaowen; Zhang, Jingbo; Li, Xueping; Xiao, Xurui; Lin, Yuan

2008-07-01

343

Anatase TiO2 nanorod-decoration for highly efficient photoenergy conversion  

NASA Astrophysics Data System (ADS)

In recent studies of inorganic materials for energy applications, surface modification processes have been shown to be among the most effective methods to enhance the performance of devices. Here, we demonstrate a facile nano-decoration method which is generally applicable to anatase TiO2 nanostructures, as well as a nano-decorated hierarchical TiO2 nanostructure which improves the energy conversion efficiency of a dye-sensitized solar cell (DSSC). Using a facile sol-gel method, 0-D, 1-D, and 2-D type anatase TiO2 nanostructures were decorated with 200 nm long anatase TiO2 nanorods to create various hierarchical nanostructures. A structural analysis reveals that the branched nanorod has a highly crystalline anatase phase with anisotropic growth in the [001] longitudinal direction. When one of the hierarchical structures, a chestnut bur-like nanostructure, was employed in a dye-sensitized solar cell as a scattering layer, offering increased dye-loading properties, preserving a sufficient level of light-scattering ability and preserving superior charge transport and recombination properties as well, the energy conversion efficiency of the cell improved by 19% (from 7.16% to 9.09%) compared to a cell with a 0-D TiO2 sphere as a scattering layer. This generally applicable anatase nanorod-decorating method offers potential applications in various energy-conversion applications, especially in DSSCs, quantum-dot solar cells, photoelectrochemical water-splitting devices, photocatalysis, and lithium ion batteries.In recent studies of inorganic materials for energy applications, surface modification processes have been shown to be among the most effective methods to enhance the performance of devices. Here, we demonstrate a facile nano-decoration method which is generally applicable to anatase TiO2 nanostructures, as well as a nano-decorated hierarchical TiO2 nanostructure which improves the energy conversion efficiency of a dye-sensitized solar cell (DSSC). Using a facile sol-gel method, 0-D, 1-D, and 2-D type anatase TiO2 nanostructures were decorated with 200 nm long anatase TiO2 nanorods to create various hierarchical nanostructures. A structural analysis reveals that the branched nanorod has a highly crystalline anatase phase with anisotropic growth in the [001] longitudinal direction. When one of the hierarchical structures, a chestnut bur-like nanostructure, was employed in a dye-sensitized solar cell as a scattering layer, offering increased dye-loading properties, preserving a sufficient level of light-scattering ability and preserving superior charge transport and recombination properties as well, the energy conversion efficiency of the cell improved by 19% (from 7.16% to 9.09%) compared to a cell with a 0-D TiO2 sphere as a scattering layer. This generally applicable anatase nanorod-decorating method offers potential applications in various energy-conversion applications, especially in DSSCs, quantum-dot solar cells, photoelectrochemical water-splitting devices, photocatalysis, and lithium ion batteries. Electronic supplementary information (ESI) available: XRD of three types of TiO2 hosts, TEM images of nanorod-decorated TiO2 hierarchical nanostructures and host 0S-TiO2, reflectance of the free-standing TiO2 nanorod, SEM images of photoelectrodes employing various scattering layers with tmax, the amount of adsorbed dye molecules per surface volume on 0S and BS monolayer films, J-V curves of the DSSCs employing each active layer with tmax thickness, the transport time constants and recombination time constants versus various scattering layer thicknesses at constant Jsc (Jsc = 0.5 mA cm-2) and the photovoltaic parameters of each DSSC employing each tmax of various scattering layers. See DOI: 10.1039/c3nr03439a

Kim, Dong Hoe; Seong, Won Mo; Park, Ik Jae; Yoo, Eun-Sang; Shin, Seong Sik; Kim, Ju Seong; Jung, Hyun Suk; Lee, Sangwook; Hong, Kug Sun

2013-11-01

344

Comparison of the killing effects between nitrogen-doped and pure TiO2 on HeLa cells with visible light irradiation  

NASA Astrophysics Data System (ADS)

The killing effect of nitrogen-doped titanium dioxide (N-TiO2) nanoparticles on human cervical carcinoma (HeLa) cells by visible light photodynamic therapy (PDT) was higher than that of TiO2 nanoparticles. To study the mechanism of the killing effect, the reactive oxygen species produced by the visible-light-activated N-TiO2 and pure-TiO2 were evaluated and compared. The changes of the cellular parameters, such as the mitochondrial membrane potential (MMP), intracellular Ca2+, and nitrogen monoxide (NO) concentrations after PDT were measured and compared for N-TiO2- and TiO2-treated HeLa cells. The N-TiO2 resulted in more loss of MMP and higher increase of Ca2+ and NO in HeLa cells than pure TiO2. The cell morphology changes with time were also examined by a confocal microscope. The cells incubated with N-TiO2 exhibited serious distortion and membrane breakage at 60 min after the PDT.

Li, Zheng; Pan, Xiaobo; Wang, Tianlong; Wang, Pei-Nan; Chen, Ji-Yao; Mi, Lan

2013-02-01

345

Design and fabrication of nanometric TiO2/Ag/TiO2/Ag/TiO2 transparent conductive electrode for inverted organic photovoltaic cells application  

NASA Astrophysics Data System (ADS)

In this study, transparent conductive TiO2/Ag/TiO2/Ag/TiO2 (TATAT) nano-multilayer system is designed and optimum thickness of TiO2 and Ag layers are calculated. TATAT nano-multilayer films were deposited on glass substrates at room temperature by a thermal evaporation technique. We investigated some electrical, optical and structural properties of optimized TATAT multilayer such as sheet resistance, optical transmittance and the root-mean-square surface roughness. Here, we suggest a very low resistance transparent electrode (2.3 (?/?)) with a high transmittance (90%) for optoelectronics applications. Inverted organic photovoltaic cell was fabricated on the TATAT cathode. The fabricated cell with 12 nm of Ag layer shows higher power conversion efficiency (2.68%) compared to that fabricated on the ITO electrode (1.84%). The results show that the TATAT multilayer system is a suitable structure for use as transparent conductive electrode in optoelectronic devices.

Ghasemi Varnamkhasti, Mohsen; Shahriari, Esmaeil

2014-05-01

346

Novel hollow mesoporous 1D TiO2 nanofibers as photovoltaic and photocatalytic materials.  

PubMed

Hollow mesoporous one dimensional (1D) TiO(2) nanofibers are successfully prepared by co-axial electrospinning of a titanium tetraisopropoxide (TTIP) solution with two immiscible polymers; polyethylene oxide (PEO) and polyvinylpyrrolidone (PVP) using a core-shell spinneret, followed by annealing at 450 °C. The annealed mesoporous TiO(2) nanofibers are found to having a hollow structure with an average diameter of 130 nm. Measurements using the Brunauer-Emmett-Teller (BET) method reveal that hollow mesoporous TiO(2) nanofibers possess a high surface area of 118 m(2) g(-1) with two types of mesopores; 3.2 nm and 5.4 nm that resulted from gaseous removal of PEO and PVP respectively during annealing. With hollow mesoporous TiO(2) nanofibers as the photoelectrode in dye sensitized solar cells (DSSC), the solar-to-current conversion efficiency (?) and short circuit current (J(sc)) are measured as 5.6% and 10.38 mA cm(-2) respectively, which are higher than those of DSSC made using regular TiO(2) nanofibers under identical conditions (? = 4.2%, J(sc) = 8.99 mA cm(-2)). The improvement in the conversion efficiency is mainly attributed to the higher surface area and mesoporous TiO(2) nanostructure. It facilitates the adsorption of more dye molecules and also promotes the incident photon to electron conversion. Hollow mesoporous TiO(2) nanofibers with close packing of grains and crystals intergrown with each other demonstrate faster electron diffusion, and longer electron recombination time than regular TiO(2) nanofibers as well as P25 nanoparticles. The surface effect of hollow mesoporous TiO(2) nanofibers as a photocatalyst for the degradation of rhodamine dye was also investigated. The kinetic study shows that the hollow mesoporous surface of the TiO(2) nanofibers influenced its interactions with the dye, and resulted in an increased catalytic activity over P25 TiO(2) nanocatalysts. PMID:22315140

Zhang, Xiang; Thavasi, Velmurugan; Mhaisalkar, S G; Ramakrishna, Seeram

2012-03-01

347

Ultrathin (0 0 1) and (1 0 0) TiO2(B) sheets: Surface reactivity and structural properties  

NASA Astrophysics Data System (ADS)

B polymorph of titanium dioxide (TiO2(B)) appears as a metastable phase during thermal annealing of low content sodium layered titanate nanostructures obtained via the widely used hydrothermal synthesis. In addition, the computed formation energy for the TiO2(B) (0 0 1) slabs in the order of the one calculated for anatase (1 0 1) which represents one of the most stable TiO2 surfaces. This encourages the study of this polymorph which could gain prominence in TiO2 applications at the nanoscale. In a first instance ultrathin TiO2(B) sheets, parallel to crystallographic planes (0 0 1) and (1 0 0), are investigated and compared to other well know TiO2 polymorphs, such as rutile and anatase surfaces. Then the adsorption of formic acid on (0 0 1) and (1 0 0) - less stable - TiO2(B) dry ultrathin sheets was studied as the first step for further evaluation of TiO2(B) nanostructures for dye sensitized solar cells (DSSC) applications. The results show that the monodentate through the carbonyl group configuration is the most stable for (0 0 1) sheet while bidentate dissociated configuration is the most stable for (1 0 0) sheet being the computed adsorption energies 0.51 eV and 1.49 eV, respectively. The evaluated reactivity of TiO2(B) slabs is comparable with anatase and indicates that it could be a good adsorbent for common dyes used for dye sensitized solar cells purposes.

Fernández-Werner, Luciana; Faccio, Ricardo; Juan, Alfredo; Pardo, Helena; Montenegro, Benjamín; Mombrú, Álvaro W.

2014-01-01

348

Microfluidic cell with a TiO 2-modified gold electrode irradiated by an UV-LED for in situ photocatalytic decomposition of organic matter and its potentiality for voltammetric analysis of metal ions  

Microsoft Academic Search

A novel microreactor for TiO2-assisted photocatalysis in a microfluidic electrochemical cell was designed and constructed by a technology that can be reproduced in any chemical laboratory. The cell is obtained by a two-step thermal transfer of laser printed masks onto gold CD-Rs, a subtractive one to define the electrodes, and an additive one to define the channels. The TiO2 nanoparticles

Daniela Daniel; Ivano G. R. Gutz

2007-01-01

349

Performance analysis of dye solar cells with various nanoparticles-aggregates mesoscopic multilayer configurations  

NASA Astrophysics Data System (ADS)

Multilayers of different TiO2 aggregate-nanoparticles compositions were utilized to improve the sensitized TiO2 dye solar cells (DSC) by light confinement in the layer. Four different TiO2 aggregate-nanoparticle composite were integrated as the photoelectrode material of DSCs and their performance and physics were investigated. TiO2 pastes of different composition ratios films were screen-printed onto transparent conducting oxide (TCO) glass and assembled into test cells. I-V characterization was conducted using solar simulator. Electrochemical impedance spectroscopy (EIS) was utilized in order to measure electron transport properties. Measurement for the quantum efficiency and spectral response of the DSCs were performed using incident photon-to-electron conversion efficiency (IPCE). DSC test cell with an optimized configuration recorded the highest overall power conversion efficiency of 4.22% under the irradiation of 100 mW/cm2 of AM 1.5 simulated sunlight.

Samsudin, Adel Eskandar; Mohamed, Norani Muti

2012-11-01

350

Nanocomposite enables sensitized solar cell  

NASA Astrophysics Data System (ADS)

Dye Sensitized solar cells (DSSCs) are a promising candidate for next generation photovoltaic panels due to their low cost, easy fabrication process, and relative high efficiency. Despite considerable effort on the advancement of DSSCs, the efficiency has been stalled for nearly a decade due to the complex interplay among various DSSC components. DSSCs consist of a photoanode on a conducting substrate, infiltrated dye for light absorption and electron injection, and an electrolyte to regenerate the dye. On the photoanode is a high band-gap semiconducting material, primarily of a nanostructure morphology of titanium (II) dioxide (TiO2), dye molecules whose molar absorption is typically in the visible spectrum, are adsorbed onto the surface of TiO 2. To improve the current DSSCs, there are many parameters that can be investigated. In a conventional DSSC, a thick semiconducting layer such as the nanoparticle TiO2 layer induces charge separation efficiently while concurrently increasing the charge transport distance, leading the cell to suffer from more charge recombination and deterioration in charge collection efficiency. To improve on this limitation, TiO2 nanowires (NW) and nanotubes (NT) are explored to replace the nanoparticle photoanode. One-dimensional nanostructures are known for the excellent electron transport properties as well as maintaining a relatively high surface area. Hence one of the focuses of this thesis explores at using different morphologies and composition of TiO2 nanostructures to enhance electron collection efficiency. Another challenge in conventional DSSCs is the limit in light absorption of solar irradiation. Dyes are limited to absorption only in the visible range, and have a low molar absorption coefficient in the near infrared (NIR). Tuning dyes is extremely complicated and may have more disadvantages than simply by extending light harvesting. Therefore our strategy is to incorporate quantum dots to replace the dye, as well as prepare a cell for the possibility of co-sensitization, thereby extending the absorption of light in the visible and NIR. The first phase of the thesis involves the synthesis and characterization of the materials used for the cell. We successfully synthesized TiO2 nanowires and nanotubes and characterized them for the use as the photoanode. Both one-dimensional structures proved to have low resistivity, chemical stability, and high density. We also synthesized lead (II) sulfide (PbS) quantum dots (QDs) and explored at modifying their diameter in order to properly control their light harvesting potential into the NIR region. The electron transport kinetics proved to be faster in one-dimensional nanostructure due to their high crystallinity order and reduced elastic scattering of the electrons during transport. Furthermore, quantum dots were synthesized such that their band-gap allowed for the absorption of NIR light. This result extended the harvesting potential of our solar cell and suggests the possibility for co-sensitization in DSSCs using dye molecules and quantum dots. Hence, the focus of this thesis work is to systematically explore a transformative way to fundamentally enhance charge transport and extend light absorption by in the incorporation of two sensitizing agents.

Phuyal, Dibya D.

351

Electronic and optical properties of TiO2 and its polymorphs by Z-scan method  

NASA Astrophysics Data System (ADS)

TiO2 is a material which has attracted considerable attention from the scientific community for its innumerable properties. TiO2 is known to exist in nature in three different crystalline structures: rutile, anatase, and brookite. Anatase and rutile TiO2 films have been widely characterized for their potential applications in solar cells, self-cleaning coatings, and photocatalysis. In the present report, the third-order nonlinear susceptibilities of TiO2 and its polymorphs, anatase, and rutile, prepared by the sol—gel technique followed by heat treatment are investigated using the Z-scan technique at a wavelength of 532 nm with a duration of 7 ns. Imaginary and real values of ?(3) for amorphous, anatase, and rutile are also calculated and found to be 5 × 10-19 m2/V2, 27 × 10-19 m2/V2, 19 × 10-19 m2/V2, respectively. It is found that the values of the optical constants of amorphous TiO2 after heat treatment vary considerably. It is assumed that this could be due to the variation in the electronic structure of TiO2 synchronous with the formation of its polymorphs, anatase, and rutile. Amorphous TiO2 is marked by the localization of the tail states near the band gap, whereas its crystalline counterparts are characterized by completely delocalized tail states.

Divya, S.; V, P. N. Nampoori; P, Radhakrishnan; A, Mujeeb

2014-08-01

352

Treatment of chlorinated solvents by TiO2 photocatalysis and photo-Fenton: influence of operating conditions in a solar pilot plant.  

PubMed

Titanium dioxide photocatalysis (using 20 0mg l(-1) of TiO2), under aerobic and anaerobic conditions, and photo-Fenton (2 and 56 mg l(-1) iron) were applied to the treatment of different NBCS (non-biodegradable chlorinated solvents), such as dichloroethane, dichloromethane and trichloromethane dissolved in water at 50 mg l(-1). All the tests were performed in a 35-l solar pilot plant with compound parabolic collectors (CPCs) under natural illumination. The two solar treatments were compared with attention to chloride release and TOC mineralisation, as the main parameters. Photo-Fenton was found to be the more appropriate treatment for these compounds, assuming volatilisation as a drawback of photocatalytic degradation of NBCS dissolved in water. In this context, several operating parameters related to NBCS degradation, e.g., treatment time, temperature, hydrogen peroxide consumption and volatility of parent compounds are discussed. The correct choice of operating conditions can very often diminish the problem of volatilisation during treatment. PMID:15620730

Rodríguez, S Malato; Gálvez, J Blanco; Rubio, Manuel I Maldonado; Ibáñez, P Fernández; Gernjak, W; Alberola, I Oller

2005-01-01

353

Determining the locus for photocarrier recombination in dye-sensitized solar cells  

E-print Network

intensity-modulated photocurrent and photovolt- age measurements in cells with the simultaneous changesDetermining the locus for photocarrier recombination in dye-sensitized solar cells Kai Zhua) and E and infrared transmittance measurements on dye-sensitized solar cells based on a mesoporous titania (TiO2

Schiff, Eric A.

354

Cost effective facile synthesis of TiO2 nanograins for flexible DSSC application using rose bengal dye  

NASA Astrophysics Data System (ADS)

Synthesis of titanium dioxide (TiO2) nanograins using economical successive ionic layer adsorption and reaction (SILAR) method has been carried out. TiO2 thin films are studied for their structural, compositional, optical and morphological properties. A layer by layer process leads to the formation of 2.4 ?m thick nanocrystalline TiO2 film. The heat treated TiO2 thin films are hydrophilic in nature with contact angle of 67°. The interconnected nanograins are employed for dye sensitized solar cells (DSSC) using inexpensive Rose Bengal (RB) dye. RB dye sensitization resulted into shifting of absorption peak from UV to visible region. The photoresponce of the dye sensitized solar cell is evaluated in the polyiodide electrolyte (0.1 M KI + 0.01 M I2) at 40 mWcm-2 illumination intensity. The TiO2 nanograins accompanied with RB sensitizer showed the conversion efficiency ( ?) of 0.89%. These results depict the strong assurance of TiO2 nanograins for DSSC application.

Jambure, Supriya Bapurao; Gund, Girish Sambhaji; Dubal, Deepak Prakash; Shinde, Sujata Sureshrao; Lokhande, Chandrakant Dnyandev

2014-09-01

355

TiO2 thin films prepared via adsorptive self-assembly for self-cleaning applications.  

PubMed

Low-cost controllable solution-based processes for preparation of titanium oxide (TiO(2)) thin films are highly desirable, because of many important applications of this oxide in catalytic decomposition of volatile organic compounds, advanced oxidation processes for wastewater and bactericidal treatments, self-cleaning window glass for green intelligent buildings, dye-sensitized solar cells, solid-state semiconductor metal-oxide solar cells, self-cleaning glass for photovoltaic devices, and general heterogeneous photocatalysis for fine chemicals etc. In this work, we develop a solution-based adsorptive self-assembly approach to fabricate anatase TiO(2) thin films on different glass substrates such as simple plane glass and patterned glass at variable compositions (normal soda lime glass or solar-grade borofloat glass). By tuning the number of process cycles (i.e., adsorption-then-heating) of TiO(2) colloidal suspension, we could facilely prepare large-area TiO(2) films at a desired thickness and with uniform crystallite morphology. Moreover, our as-prepared nanostructured TiO(2) thin films on glass substrates do not cause deterioration in optical transmission of glass; instead, they improve optical performance of commercial solar cells over a wide range of incident angles of light. Our as-prepared anatase TiO(2) thin films also display superhydrophilicity and excellent photocatalytic activity for self-cleaning application. For example, our investigation of photocatalytic degradation of methyl orange indicates that these thin films are indeed highly effective, in comparison to other commercial TiO(2) thin films under identical testing conditions. PMID:22260264

Xi, Baojuan; Verma, Lalit Kumar; Li, Jing; Bhatia, Charanjit Singh; Danner, Aaron James; Yang, Hyunsoo; Zeng, Hua Chun

2012-02-01

356

Insights into solar TiO2-assisted photocatalytic oxidation of two antibiotics employed in aquatic animal production, oxolinic acid and oxytetracycline.  

PubMed

In this study, solar driven TiO2-assisted heterogeneous photocatalytic experiments in a pilot-plant with compound parabolic collectors (CPCs) were carried out to study the degradation of two authorized veterinary antibiotics with particular relevance in finfish aquaculture, oxolinic acid (OXA) and oxytetracycline (OTC), using pure solutions of individual or mixed antibiotics. Firstly, the influence of natural solar photolysis was assessed for each antibiotic. Secondly, photocatalytic degradation kinetic rate constants for individual and mixed antibiotics were compared, using a catalyst load of 0.5 g L(-1) and an initial pH around 7.5. Thirdly, for individually photocatalytic-treated OXA and OTC in the same conditions, the growth inhibition of Escherichia coli DSM 1103 was followed, and the mineralization extent was assessed by the residual dissolved organic carbon (DOC), low-molecular-weight carboxylate anions and inorganic ions concentration. Finally, the effect of inorganic ions, such as chlorides, sulfates, nitrates, phosphates, ammonium and bicarbonates, on the photocatalytic degradation of individual solutions of OXA and OTC was also evaluated and the formation of different reactive oxygen species were probed using selective scavengers. The removal profiles of each antibiotic, both as single component or in mixture were similar, being necessary 2.5 kJ L(-1) of solar UV energy to fully remove them, and 18 kJ(UV) L(-1) to achieve 73% and 81% mineralization, for OXA and OTC, respectively. The remaining organic carbon content was mainly due to low-molecular-weight carboxylate anions. After complete removal of the antibiotics, the remaining degradation by-products no longer showed antibacterial activity. Also, 10% and 55% of the nitrogen content of each antibiotic was converted to ammonium, while no conversion to nitrite or nitrate was detected. The presence of phosphates hindered considerably the removal of both antibiotics, whereas the presence of other inorganic ions did not substantially altered the antibiotics photocatalytic degradation kinetics. PMID:23816421

Pereira, João H O S; Reis, Ana C; Queirós, Daniel; Nunes, Olga C; Borges, Maria T; Vilar, Vítor J P; Boaventura, Rui A R

2013-10-01

357

Novel hollow mesoporous 1D TiO2 nanofibers as photovoltaic and photocatalytic materials  

NASA Astrophysics Data System (ADS)

Hollow mesoporous one dimensional (1D) TiO2 nanofibers are successfully prepared by co-axial electrospinning of a titanium tetraisopropoxide (TTIP) solution with two immiscible polymers; polyethylene oxide (PEO) and polyvinylpyrrolidone (PVP) using a core-shell spinneret, followed by annealing at 450 °C. The annealed mesoporous TiO2 nanofibers are found to having a hollow structure with an average diameter of 130 nm. Measurements using the Brunauer-Emmett-Teller (BET) method reveal that hollow mesoporous TiO2 nanofibers possess a high surface area of 118 m2 g-1 with two types of mesopores; 3.2 nm and 5.4 nm that resulted from gaseous removal of PEO and PVP respectively during annealing. With hollow mesoporous TiO2 nanofibers as the photoelectrode in dye sensitized solar cells (DSSC), the solar-to-current conversion efficiency (?) and short circuit current (Jsc) are measured as 5.6% and 10.38 mA cm-2 respectively, which are higher than those of DSSC made using regular TiO2 nanofibers under identical conditions (? = 4.2%, Jsc = 8.99 mA cm-2). The improvement in the conversion efficiency is mainly attributed to the higher surface area and mesoporous TiO2 nanostructure. It facilitates the adsorption of more dye molecules and also promotes the incident photon to electron conversion. Hollow mesoporous TiO2 nanofibers with close packing of grains and crystals intergrown with each other demonstrate faster electron diffusion, and longer electron recombination time than regular TiO2 nanofibers as well as P25 nanoparticles. The surface effect of hollow mesoporous TiO2 nanofibers as a photocatalyst for the degradation of rhodamine dye was also investigated. The kinetic study shows that the hollow mesoporous surface of the TiO2 nanofibers influenced its interactions with the dye, and resulted in an increased catalytic activity over P25 TiO2 nanocatalysts.Hollow mesoporous one dimensional (1D) TiO2 nanofibers are successfully prepared by co-axial electrospinning of a titanium tetraisopropoxide (TTIP) solution with two immiscible polymers; polyethylene oxide (PEO) and polyvinylpyrrolidone (PVP) using a core-shell spinneret, followed by annealing at 450 °C. The annealed mesoporous TiO2 nanofibers are found to having a hollow structure with an average diameter of 130 nm. Measurements using the Brunauer-Emmett-Teller (BET) method reveal that hollow mesoporous TiO2 nanofibers possess a high surface area of 118 m2 g-1 with two types of mesopores; 3.2 nm and 5.4 nm that resulted from gaseous removal of PEO and PVP respectively during annealing. With hollow mesoporous TiO2 nanofibers as the photoelectrode in dye sensitized solar cells (DSSC), the solar-to-current conversion efficiency (?) and short circuit current (Jsc) are measured as 5.6% and 10.38 mA cm-2 respectively, which are higher than those of DSSC made using regular TiO2 nanofibers under identical conditions (? = 4.2%, Jsc = 8.99 mA cm-2). The improvement in the conversion efficiency is mainly attributed to the higher surface area and mesoporous TiO2 nanostructure. It facilitates the adsorption of more dye molecules and also promotes the incident photon to electron conversion. Hollow mesoporous TiO2 nanofibers with close packing of grains and crystals intergrown with each other demonstrate faster electron diffusion, and longer electron recombination time than regular TiO2 nanofibers as well as P25 nanoparticles. The surface effect of hollow mesoporous TiO2 nanofibers as a photocatalyst for the degradation of rhodamine dye was also investigated. The kinetic study shows that the hollow mesoporous surface of the TiO2 nanofibers influenced its interactions with the dye, and resulted in an increased catalytic activity over P25 TiO2 nanocatalysts. Electronic supplementary information (ESI) available. See DOI: 10.1039/c2nr11251e

Zhang, Xiang; Thavasi, Velmurugan; Mhaisalkar, S. G.; Ramakrishna, Seeram

2012-02-01

358

Solar Cells  

NASA Technical Reports Server (NTRS)

The Heat Exchanger Method (HEM) produces high efficiency crystal ingots in an automated well-insulated furnace offering low equipment, labor and energy costs. The "grown" silicon crystals are used to make solar cells, or photovoltaic cells which convert sunlight directly into electricity. The HEM method is used by Crystal Systems, Inc. and was developed under a NASA/Jet Propulsion Laboratory contract. The square wafers which are the result of the process are sold to companies manufacturing solar panels.

1983-01-01

359

A Surface Resistance Effect on the Fabrication of Dye-sensitized Solar Cell with Various Widths  

Microsoft Academic Search

Sputter deposition followed by surface treatment was studied using reactive RF plasma as a method for preparing titanium oxide (TiO2) films on the FTO (fluorine doped tin oxide, SnO2: F) substrate for dye-sensitized solar cells (DSCs). Anatase structure TiO2 films deposited by reactive RF magnetron sputtering under the conditions of Ar\\/O2 (5%) mixing gas, RF power of 600 W and

Jin-Young Choi; Hyun-Woong Seo; Mi-Jeong Kim; Ji-Young Sim; Dong-Yoon Lee; Hee-Je Kim

2008-01-01

360

A surface resistance effect on the fabrication of Dye-sensitized Solar Cell with various widths  

Microsoft Academic Search

Sputter deposition followed by surface treatment was studied using reactive RF plasma as a method for preparing titanium oxide (TiO2 ) films on the FTO (SnO2: F) substrate for dye-sensitized solar cells (DSCs). Anatase structure TiO2 films deposited by reactive RF magnetron sputtering under the conditions of Ar\\/O2 (5%) mixtures, RF power of 600W and substrate temperature of 400degC were

Jin-Young Choi; Ji-Tae Hong; Mi-Jeong Kim; Ji-Young Sim; Youl-Moon Sung; Hee-Je Kim

2006-01-01

361

Spray-deposited CuInS 2 solar cells  

Microsoft Academic Search

Spray deposition of CuInS2 offers an attractive route towards industrial production of thin-film solar cells. With spray deposition it is possible to make nanocomposites of n-type TiO2 and p-type CuInS2. Upon application of an In2S3 buffer layer, solar cells can be made with efficiencies of ?7%, being comparable to that of amorphous silicon. Rapid thermal annealing is not involved in

Albert Goossens; Joris Hofhuis

2008-01-01

362

The effect of dye coverage on the performance of dye-sensitized solar cells with a cobalt-based electrolyte.  

PubMed

The effect of dye coverage of the mesoporous TiO2 electrode on the performance of dye-sensitized solar cells based on the cobalt tris(bipyridine) electrolyte and the D35 dye was studied in detail. The dye coverage was controlled by using a dye bath with different dye concentrations and containing an inert salt, LiClO4, which was found to promote equilibrium conditions in the dye adsorption process. The amount of adsorbed D35 dye on mesoporous TiO2 was reasonably fit using the Langmuir adsorption isotherm, with a binding constant of 55?000 M(-1). Upon increasing the dye coverage on the TiO2 electrode, the electron lifetime in the dye-sensitized solar cell increased remarkably, demonstrating the blocking behavior of the D35 dye at the TiO2-electrolyte interface. Consequently, the solar cell efficiency increased dramatically with the D35 dye coverage. PMID:24668285

Pazoki, Meysam; Lohse, Peter William; Taghavinia, Nima; Hagfeldt, Anders; Boschloo, Gerrit

2014-05-14

363

Photocatalytic treatment of water-soluble pesticides by photo-Fenton and TiO 2 using solar energy  

Microsoft Academic Search

The technical feasibility and performance of photocatalytic degradation of four water-soluble pesticides (diuron, imidacloprid, formetanate and methomyl) have been studied at pilot scale in two well-defined systems of special interest because natural-solar UV light can be used: heterogeneous photocatalysis with titanium dioxide and homogeneous photocatalysis by photo-Fenton. The pilot plant is made up of compound parabolic collectors (CPCs) specially designed

S Malato; J Blanco; J Cáceres; A. R Fernández-Alba; A Agüera; A Rodr??guez

2002-01-01

364

Development of multilayered nanocrystalline TiO2 thin films for photovoltaic application  

NASA Astrophysics Data System (ADS)

Nanocrystalline multilayered thin films of TiO2 have been prepared to achieve high transparency in the wavelength range of 400-800 nm having good adhesion to the ITO substrate. TiO2 sol is synthesized through wet chemical route for making thin films by dip coating process. The layer wise optical characterization reveals higher band gap values of 3.45 eV, 3.32 eV for 2-layered and 3-layered films respectively while further depositions of thin layers followed by annealing treatment shows that the value of band gap approaches towards the bulk TiO2 considerable decrease in band gap with increase in thickness due to successive coatings of thin film is observed because of growth in crystal size as well as improving the grain contact on successive annealing treatments. Photo-conversion efficiency of the assembled solar cell is in the order of 7%.

Usha, K.; Mondal, B.; Sengupta, D.; Das, P.; Mukherjee, K.; Kumbhakar, P.

2014-04-01

365

Study on the fabrication and photovoltaic property of TiO2 mesoporous microspheres  

NASA Astrophysics Data System (ADS)

Titanium dioxide mesoporous microspheres with high surface area was successfully prepared by a facile one-step hydrothermal approach using polyethylene glycol (PEG, MW 200) as the soft template. Study shows that ˜15 nm TiO2 nanoparticles was assembled into ˜1.1 ?m mesoporous microspheres. The Brunauer-Emmett-Teller surface area of TiO2 microsphere is up to 137 m2/g. TiO2 mesoporous microspheres were fabricated onto the surface of fluorine-doped tin oxide glass and used as the photoanode of dye-sensitized solar cells, which exhibits an open circuit photovoltage of 0.80 V and an overall conversion efficiency of 6.6%. Owing to the enhanced dye loading and light-harvesting efficiency, a 26% improvement in the overall conversion efficiency was achieved when compared with the commercial Degussa P25 nanoparticles.

Tu, Luo; Pan, Hao; Xie, Haixian; Yu, Ang; Xu, Meigui; Chai, Qingli; Cui, Yuming; Zhou, Xingfu

2012-05-01

366

Nuclear microscopy as a tool in TiO2 nanoparticles bioaccumulation studies in aquatic species  

NASA Astrophysics Data System (ADS)

Engineered Titanium nanoparticles are used for a wide range of applications from coatings, sunscreen cosmetic additives to solar cells or water treatment agents. Inevitably environmental exposure can be expected and data on the ecotoxicological evaluation of nanoparticles are still scarce. The potential effects of nanoparticles of titanium dioxide (TiO2) on two model organisms, the water flea, Daphnia magna and the duckweed Lemna minor, were examined in semichronic toxicity tests. Daphnia and Lemna were exposed to TiO2 nanoparticles (average particle size value of 28 ± 11 nm (n = 42); concentration range, 1.4-25 mg/L) by dietary route and growth in medium containing the nanoparticles of TiO2, respectively. Both morphology and microdistribution of Ti in the individuals were examined by nuclear microscopy techniques. A significant amount of TiO2 was found accumulated in Daphnia exposed to nanoparticles. Nuclear microscopy imaging revealed that Ti was localized only in the digestive tract of the Daphnia, which displayed difficulty in eliminating the nanoparticles from their body. Daphnia showed higher mortality when exposed to higher concentrations of TiO2 (>10 mg/L). The exposure to TiO2 nanoparticles above 25 mg/L caused morphological alterations in Lemna. The roots became stiff and fronds colorless. The Ti mapping of cross-sections of roots and fronds showed that Ti was mainly deposited in the epidermis of the fronds and roots, with minor internalization. In summary, exposure of aquatic organisms to TiO2 nanoparticles may alter the physiology of these organisms at individual and population levels, posing risks to aquatic ecosystems.

Pinheiro, Teresa; Moita, Liliana; Silva, Luís; Mendonça, Elsa; Picado, Ana

2013-07-01

367

TiO2 nanowire electron transport pathways inside organic photovoltaics.  

PubMed

Charge transport is one of the five main steps in the operation of organic photovoltaics, but achieving balanced hole and electron transport with high mobility has been challenging in devices. Here, we report improved charge transport in organic photovoltaics via incorporation of nanostructured inorganic electron transport materials into the active layers of devices. Co-depositing TiO2 nanowires with the organic active layer solution embeds the nanowires directly within active layers of the solar cell. The ability of these nanowires to transport electrons is compared with neat P3HT:PCBM active layers and also devices containing TiO2 nanotube aggregates. Incorporation of TiO2 nanowires yields a six-fold increase in the electron mobility relative to unmodified devices, leading to a 19% improvement in the power conversion efficiency. Lower energetic disorder of the film and more balanced charge transport are also observed upon incorporating TiO2 nanowires. These advantageous effects correlate with the TiO2 nanowire length. PMID:23420471

Yang, Pinyi; Zhong, Diane K; Yuan, Mingjian; Rice, Andrew H; Gamelin, Daniel R; Luscombe, Christine K

2013-04-01

368

Formation of chelating agent driven anodized TiO2 nanotubular membrane and its photovoltaic application  

NASA Astrophysics Data System (ADS)

Titania (TiO2) nanotubular arrays provide an exciting material for dye sensitizing solar cells (DSSC) because of their large surface area, lower recombination losses, and fast charge transport properties along the nanotubes. In this paper, design of a next generation DSSC using a TiO2 nanotubular membrane is discussed. A single step, green process is developed to produce stable large area, free-standing TiO2 nanotubular films (in a short time, 30-60 min) by anodizing Ti using an organic electrolyte, containing disodium salt of ethylene diaminetetraacetic acid (Na2[H2EDTA]) as complexing agent, and subsequent drying. Transparent, crack-free TiO2 films, 20-41 µm thick containing ordered hexagonal TiO2 nanotubes are achieved by this process. Films having a geometrical area up to 16.5 cm2 with pore openings of 182 nm have been obtained. These films have been etched to form membranes which provide an exciting prospect for front side illuminated DSSC with good mass and photon transport properties as well as wettability. A photovoltaic efficiency of 2.7% is achieved using a front side illuminated DSSC compared to 1.77% using back side illumination.

Banerjee, Subarna; Misra, Mano; Mohapatra, Susanta K.; Howard, Cameron; Mohapatra, Srikanta K.; Kamilla, Sushanta K.

2010-04-01

369

Formation of chelating agent driven anodized TiO(2) nanotubular membrane and its photovoltaic application.  

PubMed

Titania (TiO(2)) nanotubular arrays provide an exciting material for dye sensitizing solar cells (DSSC) because of their large surface area, lower recombination losses, and fast charge transport properties along the nanotubes. In this paper, design of a next generation DSSC using a TiO(2) nanotubular membrane is discussed. A single step, green process is developed to produce stable large area, free-standing TiO(2) nanotubular films (in a short time, 30-60 min) by anodizing Ti using an organic electrolyte, containing disodium salt of ethylene diaminetetraacetic acid (Na(2)[H(2)EDTA]) as complexing agent, and subsequent drying. Transparent, crack-free TiO(2) films, 20-41 microm thick containing ordered hexagonal TiO(2) nanotubes are achieved by this process. Films having a geometrical area up to 16.5 cm(2) with pore openings of 182 nm have been obtained. These films have been etched to form membranes which provide an exciting prospect for front side illuminated DSSC with good mass and photon transport properties as well as wettability. A photovoltaic efficiency of 2.7% is achieved using a front side illuminated DSSC compared to 1.77% using back side illumination. PMID:20215660

Banerjee, Subarna; Misra, Mano; Mohapatra, Susanta K; Howard, Cameron; Mohapatra, Srikanta K; Kamilla, Sushanta K

2010-04-01

370

Fabrication of nano-structured TiO2 coatings using a microblast deposition technique  

NASA Astrophysics Data System (ADS)

Micron thick titanium dioxide (TiO2) coatings exhibiting a nano-structured, anatase, meso-porous structure were successfully deposited across a range of polymer, conductive glass and metallic substrates at low velocities using a microblasting technique. This process was conducted at atmospheric pressure using compressed air as the carrier gas and commercially available agglomerated nano particles of TiO2 as the feedstock. An examination of the effect of impact kinetics on the agglomerated powder before and after deposition was undertaken. A further examination of the coating microstructure along with photocurrent density measurements before and after thermal treatments was explored. Owing to the low temperature and velocity of the powder during deposition no change in phase of the powder or damage to the substrate was observed. The resulting TiO2 coatings exhibited relatively good adhesion on both titanium and FTO coated glass substrates with coating thickness of approximately 1.5 ?m. Photo-catalytic performance was measured under solar simulator illumination using a photo-electrochemical cell (PEC) with a 5-fold increase in performance observed after thermal treatment of the TiO2 coated substrates. Microblasting was demonstrated to be a rapid and cost effective method for the deposition of nano-structured, photo-catalytic, anatase TiO2 coatings.

McDonnell, Kevin A.; English, Niall J.; Stallard, Charlie P.; Rahman, Mahfujur; Dowling, Denis P.

2013-06-01

371

Hybrid micro/nano-topography of a TiO2 nanotube-coated commercial zirconia femoral knee implant promotes bone cell adhesion in vitro  

PubMed Central

Various approaches have been studied to engineer the implant surface to enhance bone in-growth properties, particularly using micro- and nano- topography. In this study, the behavior of osteoblast (bone) cells was analyzed in response to a titanium oxide (TiO2) nanotube-coated commercial zirconia femoral knee implant consisting of a combined surface structure of a micro-roughened surface with the nanotube coating. The osteoblast cells demonstrated high degrees of adhesion and integration into the surface of the nanotube-coated implant material, indicating preferential cell behavior on this surface when compared to the bare implant. The results of this brief study provide sufficient evidence to encourage future studies. The development of such hierarchical micro and nano topographical features, as demonstrated in this work, can provide for insightful designs for advanced bone-inducing material coatings on ceramic orthopedic implant surfaces. PMID:23623092

Frandsen, Christine J.; Noh, Kunbae; Brammer, Karla S.; Johnston, Gary; Jin, Sungho

2014-01-01

372

Electron transport in CuInS 2-based nanostructured solar cells  

Microsoft Academic Search

Three-dimensional solid state solar cells, or 3D-cells, are based on nanostructured n-type TiO2 electrodes as known from dye-sensitized solar cells, and completed with a p-type solid state semiconductor absorber CuInS2 which is absorber and hole conductor in one. To study the electron transport in this specific type of nanostructured solar cells, they are subjected to intensity modulated photocurrent spectroscopy. The

Catelijne Grasso; Marian Nanu; Albert Goossens; Marc Burgelman

2005-01-01

373

The effect of TiCl4 treatment on the efficiency of dye sensitized solar cell  

NASA Astrophysics Data System (ADS)

Dye sensitized solar cells (DSSC) are the new generation of solar cells that have their advantages such as transparency, flexibility and low cost production. This has certainly attracted researchers in the field of green technology to further develop DSSC. The focus is on the efficiency, as it is low at this point of time, as compared to silicon based solar cells. In this paper, the effect of TiCl4 treatment on the efficiency of DSSC by treating the conducting glass and TiO2 layer was studied and results showed that the TiCl4 treatment on the conducting glass and the printed TiO2 film increased the efficiency from 3.45% to 4.43%. The TiO2 layer was characterized by using FESEM and AFM and the efficiency of the DSSC was measured by using the sunlight simulator.

Ardakani, Seyed Esmaeil Mahdavi; Singh, Balbir Singh Mahinder; Mohammed, Norani Muti

2014-10-01

374

Study of interface properties in CuPc based hybrid inorganic-organic solar cells.  

PubMed

Metal-substituted phthalocyanine thin films such as copper-phthalocyanine (CuPc) are often used as photo-active and hole transporting layers (HTLs) in fully organic photovoltaic devices. In this work, CuPc is vacuum sublimated on an electron acceptor layer of mesoporous titania (TiO(2)) for the formation of hybrid TiO(2):CuPc solar cell devices. The performance of these hybrid solar cell devices was demonstrated without and with dye sensitization at the TiO(2):CuPc interface. The charge separation and photocurrent contribution at the interfaces in these multilayer hybrid devices was studied by using a variety of optoelectrical and photophysical characterization techniques. It is important to understand the fundamental interface properties of these multilayer hybrid solar cell devices for optimized performance. PMID:22890562

Thalluri, Gopala Krishna V V; Spoltore, Donato; Piersimoni, Fortunato; Clifford, John N; Palomares, Emilio; Manca, Jean V

2012-10-01

375

Hyaluronic acid immobilization on the poly-allylamine coated nano-network TiO2 surface.  

PubMed

Recently, biocompatibility report revealed that the TiO2 nano-network (TiO2 NT) structure has much higher cells colonization than the native TiO2 on Ti surface. In this study, we prepared the hyaluronic acid (HA) immobilized TiO2 NT layer by plasma surface modification and then evaluated biological behavior of MC3T3-E1 on the Ti, TiO2 NT and TiO2 NT/NH2/HA surface. The cell viability tests revealed slightly enhanced viability on the TiO2 NT/NH2/HA surfaces than on the untreated Ti surfaces. PMID:22103192

Shim, Jae-Won; Lee, Kang; Jeong, Moon-Jin; Jung, Sang-Chul; Kim, Byung-Hoon

2011-08-01

376

Layered insulator hexagonal boron nitride for surface passivation in quantum dot solar cell  

NASA Astrophysics Data System (ADS)

Single crystalline, two dimensional (2D) layered insulator hexagonal boron nitride (h-BN), is demonstrated as an emerging material candidate for surface passivation on mesoporous TiO2. Cadmium selenide (CdSe) quantum dot based bulk heterojunction (BHJ) solar cell employed h-BN passivated TiO2 as an electron acceptor exhibits photoconversion efficiency ˜46% more than BHJ employed unpassivated TiO2. Dominant interfacial recombination pathways such as electron capture by TiO2 surface states and recombination with hole at valence band of CdSe are efficiently controlled by h-BN enabled surface passivation, leading to improved photovoltaic performance. Highly crystalline, confirmed by transmission electron microscopy, dangling bond-free 2D layered h-BN with self-terminated atomic planes, achieved by chemical exfoliation, enables efficient passivation on TiO2, allowing electronic transport at TiO2/h-BN/CdSe interface with much lower recombination rate compared to an unpassivated TiO2/CdSe interface.

Shanmugam, Mariyappan; Jain, Nikhil; Jacobs-Gedrim, Robin; Xu, Yang; Yu, Bin

2013-12-01

377

Nanofibrous TiO2-core/conjugated polymer-sheath composites: synthesis, structural properties and photocatalytic activity.  

PubMed

Nanofibrous TiO2-core/conjugated polymer-sheath composite nanocables were synthesized by in-situ chemical oxidative polymerization of aniline with oxidant in the presence of TiO, nanofibers prepared through an electrospinning process. During the polymerization process, aniline molecules were adsorbed on the surface of TiO2. Upon the addition of oxidant, the polymerization of aniline takes place on the surface of the TiO2 nanofibers and polyaniline (PANI) is gradually deposited on their surface. The resulting TiO2-PANI nanocomposites have a coaxial nanocable structure. The morphological and structural properties of the composite nanocables were analyzed by using high resolution transmission electron microscopy (HRTEM), scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier-transform infrared (FT-IR) and UV-visible spectroscopy (UV-vis), respectively. The HRTEM images proved that PANI (20 nm thickness) covered the surface of the TiO2 nanofibers. Also, the photocatalytic activity for the degradation of organic dyes on fibrous photocatalysts under UV-light was studied. The photocatalytic experiments showed that dye could be degraded more efficiently on the TiO2-PANI composite nanocables than on pure TiO2, due to the charge transfer from PANI to TiO2. The method for the synthesis of these unique structured composite nanocables is simple, rapid and reproducible. This facile method may be developed to produce multifunctional nanocomposites of various polymers with metal oxide fibers on a large scale for various technological applications such as sensors, solar cells, and catalysts. PMID:21121282

Reddy, Kakarla Raghava; Nakata, Kazuya; Ochiai, Tsuyoshi; Murakami, Taketoshi; Tryk, Donald A; Fujishima, Akira

2010-12-01

378

Hydrogen-treated TiO2 nanowire arrays for photoelectrochemical water splitting.  

PubMed

We report the first demonstration of hydrogen treatment as a simple and effective strategy to fundamentally improve the performance of TiO(2) nanowires for photoelectrochemical (PEC) water splitting. Hydrogen-treated rutile TiO(2) (H:TiO(2)) nanowires were prepared by annealing the pristine TiO(2) nanowires in hydrogen atmosphere at various temperatures in a range of 200-550 °C. In comparison to pristine TiO(2) nanowires, H:TiO(2) samples show substantially enhanced photocurrent in the entire potential window. More importantly, H:TiO(2) samples have exceptionally low photocurrent saturation potentials of -0.6 V vs Ag/AgCl (0.4 V vs RHE), indicating very efficient charge separation and transportation. The optimized H:TiO(2) nanowire sample yields a photocurrent density of ?1.97 mA/cm(2) at -0.6 V vs Ag/AgCl, in 1 M NaOH solution under the illumination of simulated solar light (100 mW/cm(2) from 150 W xenon lamp coupled with an AM 1.5G filter). This photocurrent density corresponds to a solar-to-hydrogen (STH) efficiency of ?1.63%. After eliminating the discrepancy between the irradiance of the xenon lamp and solar light, by integrating the incident-photon-to-current-conversion efficiency (IPCE) spectrum of the H:TiO(2) nanowire sample with a standard AM 1.5G solar spectrum, the STH efficiency is calculated to be ?1.1%, which is the best value for a TiO(2) photoanode. IPCE analyses confirm the photocurrent enhancement is mainly due to the improved photoactivity of TiO(2) in the UV region. Hydrogen treatment increases the donor density of TiO(2) nanowires by 3 orders of magnitudes, via creating a high density of oxygen vacancies that serve as electron donors. Similar enhancements in photocurrent were also observed in anatase H:TiO(2) nanotubes. The capability of making highly photoactive H:TiO(2) nanowires and nanotubes opens up new opportunities in various areas, including PEC water splitting, dye-sensitized solar cells, and photocatalysis. PMID:21710974

Wang, Gongming; Wang, Hanyu; Ling, Yichuan; Tang, Yuechao; Yang, Xunyu; Fitzmorris, Robert C; Wang, Changchun; Zhang, Jin Z; Li, Yat

2011-07-13

379

Large-diameter titanium dioxide nanotube arrays as a scattering layer for high-efficiency dye-sensitized solar cell  

PubMed Central

Large-sized titanium dioxide (TiO2) nanotube arrays with an outer diameter of approximately 500 nm have been successfully synthesized by potentiostatic anodization at 180 V in a used electrolyte with the addition of 1.5 M lactic acid. It is found that the synthesized large-diameter TiO2 nanotube array shows a superior light scattering ability, which can be used as a light scattering layer to significantly enhance the efficiency of TiO2 nanoparticle-based dye-sensitized solar cells from 5.18% to 6.15%. The remarkable light scattering ability makes the large-diameter TiO2 nanotube array a promising candidate for light management in dye-sensitized solar cells (DSSCs). PMID:25114652

2014-01-01

380

Knudsen cell mass spectrometric investigation of the PbO-ZrO(2)-TiO(2) system.  

PubMed

Knudsen effusion mass spectrometry (KEMS) was used for direct determination of lead oxide activity as a function of temperature in various regions of the PbO-ZrO(2)-TiO(2) system. From the results, the enthalpy, Gibbs free energy and entropy of formation of PbTiO(3) (PT), PbZrO(3) (PZ) and Pb(Zr,Ti)O(3) (PZT) were evaluated. In addition, the single phase widths of Pb(Zr(0.5)Ti(0.5))O(3) and PbTiO(3) perovskite structures were determined at 1100 K. The reaction rate of PZT synthesis in vacuo was followed by direct measurement of the change of PbO activity with time. Lead oxide activity in stoichiometric Pb(Zr(0.5)Ti(0.5))O(3), PbTiO(3) and Pb(0.968)(Zr(0.5)Ti(0.5))O(2.968) (3% lead deficient) at 850 degrees C was found to be 0.40, 0.45 and 0.1, respectively. PZT, PT and PZ powder samples prepared by a solid state procedure were also measured, all revealing lead deficiency. Copyright 1999 John Wiley & Sons, Ltd. PMID:10407290

Popovic; Malic; Bencze

1999-06-01

381

Light trapping in nanotube-based dye-sensitized solar cells  

NASA Astrophysics Data System (ADS)

We describe a design for a photonic crystal dye-sensitized solar cell (DSSC) that can attain at least a factor of one-third enhancement in solar light absorption relative to a conventional cell. The design consists of a periodic array of modulated-diameter TiO2 nanotubes filled with TiO2 nanoparticles and interstitial regions filled with electrolyte. Using nanotubes filled with nanoparticles provides not only light trapping and absorption enhancement, but offers improved electrical transport through the nanotube walls. Keeping the volume of dye-coated TiO2 nanoparticles in the cell constant, our design gives a maximum achievable photocurrent density (MAPD) of over 21mA/cm2 in 2D simulations, well beyond the current record for C101-based cells. The design is shown to be feasible using current manufacturing techniques.

Foster, S.; John, S.

2013-09-01

382

Characterization of siloxane adsorbates covalently attached to TiO2  

NASA Astrophysics Data System (ADS)

Siloxanes with the general formula R-(CH2)n-Si-(OR')3 form durable bonds with inorganic materials upon hydrolysis of labile -OR' groups, and serve as robust coupling agents between organic and inorganic materials. In the field of dye-sensitized solar cells, functionalization of TiO2 thin-films with siloxane adsorbates has been shown to be useful as a surface-passivation technique that hinders recombination processes and improves the overall efficiency of light-to-electricity conversion. However, the attachment of siloxane adsorbates on TiO2 surfaces still remains poorly understood at the molecular level. In this paper, we report the characterization of 3-(triethoxysilyl) propionitrile (TPS) adsorbates, covalently attached onto TiO2 surfaces. We combine synthetic methods based on chemical vapor deposition, Fourier transform (FT) infrared (IR) spectroscopy and electronic structure calculations based on density functional theory (DFT). We predict that trifunctional siloxanes form only 2 covalent bonds, in a 'bridge' mode with adjacent Ti4+ ions on the TiO2 surface, leaving 'dangling' alkoxy groups on the surface adsorbates. Our findings are supported by the observation of a prominent fingerprint band at 1000-1100 cm-1, assigned to Si-O-C stretching modes, and by calculations of binding enthalpies at the DFT B3LYP/(LACVP/6-31G**) level of theory indicating that the 'bridge' binding (?Hb= -55 kcal mol-1) is more stable than 'tripod' motifs (?Hb= -45 kcal mol-1) where siloxanes form 3 covalent bonds with the TiO2 surface. The alkoxysiloxane groups are robust under heat and water treatment and are expected to be particularly relevant for analytical methods since they could be exploited for immobilizing other functionalities onto the TiO2 surfaces.

Iguchi, Nobuhito; Cady, Clyde; Snoeberger, Robert C., III; Hunter, Bryan M.; Sproviero, Eduardo M.; Schmuttenmaer, Charles A.; Crabtree, Robert H.; Brudvig, Gary W.; Batista, Victor S.

2008-08-01

383

Effects of 1064 nm laser on the structural and optical properties of nanostructured TiO2 thin film  

NASA Astrophysics Data System (ADS)

TiO2 thin film has been widely used as photoelectrode in dye-sensitized solar cells. It can also be used in quantum dot synthesized solar cells. Study of its effects in different spectrum of light is important for its use in solar cells. We have reported effects of 1064 nm laser on the surface morphology, structural and optical properties of nanostructured TiO2 thin film deposited on glass substrates using sol-gel spin coating technique. Q-Switched Nd:YAG pulsed laser at various power densities is used in this study. Surface morphology of the film is investigated using X-ray diffraction (XRD) and atomic force microscopy technique. The XRD pattern of as deposited TiO2 thin film is amorphous and after laser exposure it became TiO2 anatase structure. Atomic force microscopy of the crystalline TiO2 thin film shows that the grain size increases by increasing laser power density. The calculations of the band gap are carried out from UV/Visible spectroscopy measurements with JASCO spectrometer. For laser power density of 25 MW/cm2 there is an increase in the transmission and it decreases at the value of 38 MW/cm2 and band gap decreases with increasing laser power density. Photoluminescence spectra of the crystalline TiO2 thin film indicate two broad peaks in the range of 415 and 463 nm, one for band gap peak (415 nm) and other for oxygen defect during film deposition process.

Aslam Farooq, W.; Atif, M.; Ali, Syed Mansoor; Fatehmulla, Amanullah; Aslam, M.

2014-09-01

384

The effect of a blocking layer on the photovoltaic performance in CdS quantum-dot-sensitized solar cells  

Microsoft Academic Search

In order to reduce the surface recombination at the interface between the fluorine-doped tin oxide (FTO) substrate and the polysulfide electrolyte in CdS quantum-dot-sensitized solar cells (QDSCs), compact TiO2 is deposited on the FTO electrode by sputtering. The TiO2-coated CdS-sensitized solar cell exhibits enhanced power-conversion efficiency (0.52%) compared with a bare CdS-sensitized solar cell (0.23%). Charge-transfer kinetics are analyzed by

Jongmin Kim; Hongsik Choi; Changwoo Nahm; Joonhee Moon; Chohui Kim; Seunghoon Nam; Dae-Ryong Jung

2011-01-01

385

The effect of compression on electron transport and recombination in plastic TiO 2 photoanodes  

Microsoft Academic Search

The compression method was applied for the preparation of plastic TiO2 porous films on a conductive indium–tin oxide (ITO)-coated polyethylene naphthalate (PEN) substrate at low temperature for the generation of high-efficiency plastic dye-sensitized solar cells (DSCs). The compression parameters, including pressure and time, were varied in order to determine their effect on the photovoltaic performance of the plastic DSCs. The

Xiaochong Zhao; Hong Lin; Xin Li; Jianbao Li

2011-01-01

386

2D ZnIn2S4 Nanosheet/1D TiO2 Nanorod Heterostructure Arrays for Improved Photoelectrochemical Water Splitting.  

PubMed

We report the fabrication of 2D ZnIn2S4 nanosheet/1D TiO2 nanorod heterojunction arrays by a facile hydrothermal process and their use as photoelectrodes in a photoelectrochemical (PEC) cell for high-performance solar water splitting. The morphology, microstructure, and phase of pristine TiO2 and 2D ZnIn2S4 nanosheet/1D TiO2 nanorod heterojunction arrays were characterized in detail. PEC measurements showed that 2D/1D heterojunction arrays offered enhanced photocurrent density (3 times higher than that of pristine TiO2), negatively shifted onset potential from 0.05 to -0.53 V, and high light on/off cycle stability. Electrochemical impedance investigation attested to a significant improvement of the interface electron transfer kinetics in this heterojunction, thus facilitating electron-hole separation, transfer, and collection, which resulted in enhanced PEC properties. PMID:25225738

Liu, Qiong; Lu, Hao; Shi, Zhiwei; Wu, Fangli; Guo, Jun; Deng, Kaimo; Li, Liang

2014-10-01

387

Highly self-ordered nanochannel TiO2 structures by anodization in a hot glycerol electrolyte.  

PubMed

In the present work, we report on the self-organized growth of TiO(2) layers consisting of a highly aligned nanochannel morphology. We show that an electrochemical anodization process of Ti in a hot glycerol/K(2)HPO(4) electrolyte can be adjusted to yield these self-organized TiO(2) structures. The channel diameter and length are controllable by the anodization parameters. This directional structure can, for example, find application in dye-sensitized solar cells. PMID:21494725

Lee, Kiyoung; Kim, Doohun; Schmuki, Patrik

2011-05-28

388

Quantum rod-sensitized solar cell: nanocrystal shape effect on the photovoltaic properties.  

PubMed

The effect of the shape of nanocrystal sensitizers in photoelectrochemical cells is reported. CdSe quantum rods of different dimensions were effectively deposited rapidly by electrophoresis onto mesoporous TiO(2) electrodes and compared with quantum dots. Photovoltaic efficiency values of up to 2.7% were measured for the QRSSC, notably high values for TiO(2) solar cells with ex situ synthesized nanoparticle sensitizers. The quantum rod-based solar cells exhibit a red shift of the electron injection onset and charge recombination is significantly suppressed compared to dot sensitizers. The improved photoelectrochemical characteristics of the quantum rods over the dots as sensitizers is assigned to the elongated shape, allowing the build-up of a dipole moment along the rod that leads to a downward shift of the TiO(2) energy bands relative to the quantum rods, leading to improved charge injection. PMID:22452287

Salant, Asaf; Shalom, Menny; Tachan, Zion; Buhbut, Sophia; Zaban, Arie; Banin, Uri

2012-04-11

389

Dust in brown dwarfs and extra-solar planets IV. Assessing TiO2 and SiO nucleation for cloud formation modeling  

E-print Network

Clouds form in atmospheres of brown dwarfs and planets. The cloud particle formation processes are similar to the dust formation process studied in circumstellar shells of AGB stars and in Supernovae. Cloud formation modelling in substellar objects requires gravitational settling and element replenishment in addition to element depletion. All processes depend on the local conditions, and a simultaneous treatment is required. We apply new material data in order to assess our cloud formation model results regarding the treatment of the formation of condensation seeds. We re-address the question of the primary nucleation species in view of new (TiO2)_N-cluster data and new SiO vapour pressure data. We apply the density functional theory using the computational chemistry package Gaussian 09 to derive updated thermodynamical data for (TiO2)_N-clusters as input for our TiO2 seed formation model. We test different nucleation treatments and their effect on the overall cloud structure by solving a system of dust momen...

Lee, G; Giles, H; Bromley, S T

2014-01-01

390

Natural dye extract of lawsonia inermis seed as photo sensitizer for titanium dioxide based dye sensitized solar cells  

NASA Astrophysics Data System (ADS)

Natural dye extract of lawsonia inermis seed were used as photo sensitizer to fabricate titanium dioxide nanoparticles based dye sensitized solar cells. Pure titanium dioxide (TiO2) nanoparticles in anatase phase were synthesized by sol-gel technique and pre dye treated TiO2 nanoparticles were synthesized using modified sol-gel technique by mixing lawsone pigment rich natural dye during the synthesis itself. This pre dye treatment with natural dye has yielded colored TiO2 nanoparticles with uniform adsorption of natural dye, reduced agglomeration, less dye aggregation and improved morphology. The pure and pre dye treated TiO2 nanoparticles were subjected to structural, optical, spectral and morphological studies. Dye sensitized solar cells (DSSC) fabricated using the pre dye treated and pure TiO2 nanoparticles sensitized by natural dye extract of lawsonia inermis seed showed a promising solar light to electron conversion efficiency of 1.47% and 1% respectively. The pre dye treated TiO2 based DSSC showed an improved efficiency of 47% when compared to that of conventional DSSC.

Ananth, S.; Vivek, P.; Arumanayagam, T.; Murugakoothan, P.

2014-07-01

391

Influence of TiCl4 Treatment on Structure and Performance of Dye-Sensitized Solar Cells  

NASA Astrophysics Data System (ADS)

Titanium dioxide (TiO2) electrodes are vital components for the fabrication of dye-sensitized solar cells (DSSC). Titanium tetrachloride (TiCl4) treatment is usually adopted as a pre- or post-treatment for the improvement of TiO2 electrodes in DSSCs. Previous reports associated these treatments with the improvement of bonding strength between the fluorinated tin oxide (FTO) substrate and the porous TiO2 layer, blocking the charge recombination at the interface between the FTO and electrolyte, but pre- and post-treatment effects were not studied simultaneously. In this study, three types of TiO2 electrode, untreated, post-treated, and pre- and post-treated, were fabricated. After the TiCl4 treatment of TiO2 electrodes, they were immersed in a dye solution and cells were assembled. Cell performance was measured using a solar light simulator at an intensity of 1000 W.m-2. The best result was achieved by the pre- and post-treated TiO2 electrode. The performance of the cell was improved by increasing the thickness of electrodes and this would raise the overall conversion efficiency up to 7.5%.

Sedghi, Arman; Nourmohammadi Miankushki, Hoda

2013-07-01

392

Characterization of N3 dye adsorption on TiO2 using quartz-crystal microbalance with dissipation monitoring  

NASA Astrophysics Data System (ADS)

Understanding the kinetics of dye adsorption on semiconductors is crucial for designing dye-sensitized solar cells (DSSCs) with enhanced efficiency. Harms et al. recently applied the Quartz-Crystal Microbalance with Dissipation Monitoring (QCM-D) to study in situ dye adsorption on flat TiO2 surfaces. QCM-D measures adsorption in real time and therefore allows one to determine the kinetics of the process. In this work, we characterize the adsorption of N3, a commercial RuBipy dye, using the native oxide layer of a titanium sensor to simulate the TiO2 substrate of a DSSC. We report equilibrium constants that are in agreement with previous absorbance studies of N3 adsorption, and therefore demonstrate the native oxide layer of a titanium sensor as a valid and readily available planar TiO2 morphology to study dye adsorption.

Wayment-Steele, Hannah K.; Johnson, Lewis E.; Dixon, Matthew C.; Johal, Malkiat S.

2013-09-01

393

Fabrication of transparent conductive oxide-less dye-sensitized solar cells consisting of Ti electrodes by electron-beam evaporation process  

Microsoft Academic Search

In this paper, we report a fabrication process of transparent conductive oxide (TCO)-less dye-sensitized solar cell. In the proposed cell fabrication process, TCO electrode is replaced with Ti electrode. Ti layer is deposited by electron beam evaporation method on the backside of the printed TiO2 layer. Due to the relatively rough surface of TiO2 printing layer, deposited Ti electrode has

Yun-Gi Kim; Choung-Hwan Shim; Dong-Hyun Kim; Hae June Lee; Ho-Jun Lee

394

Solvent-induced surface state passivation reduces recombination in semisquarylium dye-sensitized solar cells  

NASA Astrophysics Data System (ADS)

The semisquarylium dye SY1T that is strongly bound to the surface of nanocrystalline TiO2 experiences very fast back-electron transfer of injected electrons to the SY1T cation, when the TiO2/SY1T interface is surrounded by ultrahigh vacuum. However, when located in methoxypropionitrile (MPN), which is frequently used as electrolyte solvent in dye-sensitized solar cells, the back-electron transfer is significantly retarded. Results are obtained both for picosecond and microsecond time scales using transient absorption spectroscopy. As solvent-induced interfacial energy level shifts can be excluded as possible cause, the role of TiO2 surface states in the beneficial retardation process is investigated. Highly surface sensitive synchrotron-induced photoelectron spectroscopy exhibits high densities of surface states on the pristine nanocrystalline TiO2 (nc-TiO2) surfaces. While SY1T dye-sensitization from a SY1T solution in tetrahydrofuran saturates about 30% of the surface states, the subsequent in-situ adsorption of MPN molecules at the TiO2/SY1T interface leads to further reduction by more than 50% of the remaining surface states. It is concluded that the saturation of TiO2 surface states hampers the otherwise efficient recombination of injected electrons with the SY1T dye cation.

Bartelt, Andreas F.; Schütz, Robert; Strothkämper, Christian; Kastl, Ivo; Janzen, Stephan; Friedrich, Dennis; Calvet, Wolfram; Fuhrmann, Gerda; Danner, David; Scheller, Lars-Peter; Nelles, Gabriele; Eichberger, Rainer

2014-06-01

395

Solution processable titanium dioxide precursor and nanoparticulated ink: application in Dye Sensitized Solar Cells.  

PubMed

Colloidal TiO2 anatase nanoparticles of 4-8 nm diameter capped with 3,6,9-trioxadecanoic acid (TODA) were synthesized at low temperature using water and ethanol as the solvents. ATR-FTIR and (1)H NMR characterization showed the capping acid capability of stabilizing the TiO2 nanoparticles through labile hydrogen bonds. The presence of the capping ligand permitted the further preparation of homogeneous and stable colloidal dispersions of the TiO2 powder in aqueous media. Moreover, after solvent evaporation, the ligand could be easily eliminated by soft treatments, such as UV irradiation or low-temperature thermal annealing. These properties have been used in this work to fabricate mesoporous TiO2 electrodes, which can be applied as photoanodes in Dye Sensitized Solar Cells (DSSCs). For the preparation of the electrodes, the as-synthesized mesoporous TiO2 nanoparticles were mixed with commercial TiO2 (Degussa P25) and deposited on FTO substrates by using the doctor blade technique. A mixture of water and ethanol was used as the solvent. A soft thermal treatment at 140 °C for 2h eliminated the organic compound and produced a sintered mesoporous layer of 6 ?m thickness. The photovoltaic performance of the DSSCs applying these electrodes sensitized with the N3 dye resulted in 5.6% power conversion efficiency. PMID:24326146

Bosch-Jimenez, Pau; Yu, Youhai; Lira-Cantu, Mónica; Domingo, Concepción; Ayllón, José A

2014-02-15

396

Adherence of human mesenchymal stem cells on Ti and TiO2 nano-columnar surfaces fabricated by glancing angle sputter deposition  

NASA Astrophysics Data System (ADS)

The interaction of human mesenchymal stem cells (hMSCs) with Ti and TiO2 nano-columnar surfaces fabricated using glancing angle sputter deposition was investigated. The adherence and proliferation of hMSCs on different nano-columnar surfaces, including vertical columns, slanted columns and chevrons, were examined with calcein-acetoxymethyl ester fluorescence staining and scanning electron microscopy. For comparison, adherence of hMSCs on compact, dense films was also studied. After 24 h and 7 days, adherent and viable cells were observed on both, Ti nano-columns as well as dense Ti films, which confirms the biocompatibility of these nanostructures. Very small pseudopodia with width of approximately 20-35 nm and length varying from 20 to 200 nm were observed between the nano-columns, independent of the type of the nano-columnar morphology. Large inter-column spacing and effectively increased surface area make these nanostructures promising candidates for bio-functionalization or drug loading on the surface of Ti-based implants.

Motemani, Yahya; Greulich, Christina; Khare, Chinmay; Lopian, Michael; Buenconsejo, Pio John S.; Schildhauer, Thomas A.; Ludwig, Alfred; Köller, Manfred

2014-02-01

397

On the advancement of quantum dot solar cell performance through enhanced charge carrier dynamics  

NASA Astrophysics Data System (ADS)

The quantum dot solar cell is one of the few solar technologies which promises to compete with fossil fuels, but work is still needed to increase its performance. Electron transfer kinetics at interfaces and limitations of the redox couple within the cell, are responsible for lowering power conversion efficiency. Several techniques which are able to increase electron transfer within the working electrode and at the counter electrode/electrolyte interface are discussed in this dissertation. Trap sites on the surface of CdSe quantum dots are created when mercaptopropionic acid (MPA) is added to the suspension. The trap sites are emissive creating a loss pathway for photogenerated charges which will manifest as reduced photocurrent. MPA displaces amines on the surface of CdSe creating Se vacancies. Emission properties are controlled by the concentration of MPA. Because trap sites are generated, a more successful method to sensitize TiO2 films is the SILAR technique which directly grows quantum dots on the desired surface. Anodically etched TiO2 nanotubes yield photocurrents 20% greater than TiO2 nanoparticles because of longer electron diffusion lengths. Peak incident photon to charge carrier efficiencies of TiO2 nanotube samples show a doubling of photocurrent in the visible region compared to nanoparticles. The TiO2 substrates are sensitized with CdS by the SILAR process which is found to utilize both the inside and outside surfaces of the TiO2 nanotubes. Etched TiO2 nanotubes are removed from the underlying titanium foil in order to use spectroscopic techniques. Ultrafast transient absorption shows the extremely fast nature of charge injection from SILAR CdS into TiO 2 nanotubes. Surface area analysis of TiO2 nanotube powder gives an area of 77m2/g, a value 1.5 times larger than traditional TiO2 nanoparticles. By isolating the counter electrode with a salt bridge the effect of the polysulfide electrolyte is found to act as an electron scavenger on the working electrode. Though activity at the platinum counter electrode increases with the presence of polysulfides, the activity is too low to counteract scavenging at the working electrode. Cu2S, CoS and PbS electrochemically show promise as alternatives to platinum. Cu2S and CoS produce higher photocurrents and fill factors, greatly improving cell performance.

Baker, David R.

398

Dye-sensitized solar cells based on multiwalled carbon nanotube-titania/titania bilayer structure photoelectrode.  

PubMed

Dye-sensitized solar cells (DSSCs) were fabricated using multiwalled carbon nanotube (MWCNT)-TiO(2) nanocomposite as a light scattering layer. Morphology of the MWCNT-TiO(2) film was investigated by field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM). FESEM and TEM images demonstrate that MWCNTs and TiO(2) nanoparticles can be dispersed with chitosan. Internal resistance in the DSSC was characterized by electrochemical impedance spectroscopy (EIS). EIS results reveal a decrease in the charge resistance of electrolyte/dye/MWCNT-TiO(2)/TiO(2) interface with increasing MWCNT content up to 3 wt% which leads to an improvement in the photovoltaic performance. Compare with a nanocrystalline TiO(2) single-layer cell, the DSSC based on the MWCNT (3 wt%)-TiO(2)/TiO(2) bilayer structure photoelectrode shows ~100% increase in solar-to-electric energy conversion efficiency, which is attributed to the inclusion of MWCNTs in TiO(2) matrix. PMID:21463866

Lin, Wei-Jhih; Hsu, Chun-Tsung; Tsai, Yu-Chen

2011-06-15

399

Space solar cell research  

SciTech Connect

New solar cell technologies are emerging that could replace silicon cells in power-conversion applications. Gallium arsenide, indium phosphide, and other semiconducting compounds are the focal point of an expanding research effort. The primary subject matter of the article is divided into the following areas: Space vs. terrestrial cell efficiency; Space solar cells; Silicon Cells; Gallium arsenide cells; Other space solar cells; Indium phosphide cells; Superlattice solar cells.

Flood, D.J.

1989-04-01

400

Carbon-deposited TiO2 3D inverse opal photocatalysts: visible-light photocatalytic activity and enhanced activity in a viscous solution.  

PubMed

We for the first time demonstrated carbon-deposited TiO2 inverse opal (C-TiO2 IO) structures as highly efficient visible photocatalysts. The carbon deposition proceeded via high-temperature pyrolysis of phloroglucinol/formaldehyde resol, which had been coated onto the TiO2 IO structures. Carbon deposition formed a carbon layer and doped the TiO2 interface, which synergistically enhanced visible-light absorption. We directly measured the visible-light photocatalytic activity by constructing solar cells comprising the C-TiO2 IO electrode. Photocatalytic degradation of organic dyes in a solution was also evaluated. Photocatalytic dye degradation under visible light was only observed in the presence of the C-TiO2 IO sample and was increased with the content of carbon deposition. The IO structures could be readily decorated with TiO2 nanoparticles to increase the surface area and enhance the photocatalytic activity. Notably, the photocatalytic reaction was found to proceed in a viscous polymeric solution. A comparison of the mesoporous TiO2 structure and the IO TiO2 structure revealed that the latter performed better as the solution viscosity increased. This result was attributed to facile diffusion into the fully connected and low-tortuosity macropore network of the IO structure. PMID:24266769

Lee, Sunbok; Lee, Youngshin; Kim, Dong Ha; Moon, Jun Hyuk

2013-12-11

401

Preparation and properties of antibacterial TiO2@C/Ag core-shell composite  

NASA Astrophysics Data System (ADS)

An environment-friendly hydrothermal method was used to prepare TiO2@C core-shell composite using TiO2 as core and sucrose as carbon source. TiO2@C served as a support for the immobilization of Ag by impregnation in silver nitrate aqueous solution. The chemical structures and morphologies of TiO2@C and TiO2@C/Ag composite were characterized by x-ray diffraction, transmission electron microscopy, Fourier transform infrared spectroscopy, energy dispersive x-ray spectroscopy and Brunauer-Emmett-Teller (BET) analysis. The antibacterial properties of the TiO2@C/Ag core-shell composite against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) were examined by the viable cell counting method. The results indicate that silver supported on the surface of TiO2@C shows excellent antibacterial activity.

Tan, San-Xiang; Tan, Shao-Zao; Chen, Jing-Xing; Liu, Ying-Liang; Yuan, Ding-Sheng

2009-08-01

402

Biological construction of single-walled carbon nanotube electron transfer pathways in dye-sensitized solar cells.  

PubMed

We designed and mass-produced a versatile protein supramolecule that can be used to manufacture a highly efficient dye-sensitized solar cell (DSSC). Twelve single-walled carbon-nanotube (SWNT)-binding and titanium-mineralizing peptides were genetically integrated on a cage-shaped dodecamer protein (CDT1). A process involving simple mixing of highly conductive SWNTs with CDT1 followed by TiO2 biomineralization produces a high surface-area/weight TiO2 -(anatase)-coated intact SWNT nanocomposite under environmentally friendly conditions. A DSSC with a TiO2 photoelectrode containing 0.2?wt?% of the SWNT-TiO2 nanocomposite shows a current density improvement by 80?% and a doubling of the photoelectric conversion efficiency. The SWNT-TiO2 nanocomposite transfers photon-generated electrons from dye molecules adsorbed on the TiO2 to the anode electrode swiftly. PMID:25111295

Inoue, Ippei; Watanabe, Kiyoshi; Yamauchi, Hirofumi; Ishikawa, Yasuaki; Yasueda, Hisashi; Uraoka, Yukiharu; Yamashita, Ichiro

2014-10-01

403

Laser-Sintered $\\\\hbox{TiO}_{2}$ Films for Dye Solar Cell Fabrication: An Electrical, Morphological, and Electron Lifetime Investigation  

Microsoft Academic Search

We have carried out a systematic and combined I-V , electrochemical impedance spectroscopy (EIS), and scan- ning emission microscopy (SEM) investigation of dye solar cells (DSCs) fabricated with laser-sintered TiO2 photoanodes as a function of laser-integrated fluence ?. We show that the electron lifetime ?oc in the TiO2 film extracted from EIS spectra monoton- ically increases with laser sintering fluence

Girolamo Mincuzzi; Luigi Vesce; Massimiliano Liberatore; Andrea Reale; Aldo Di Carlo; Thomas M. Brown

2011-01-01

404

Comparison of charge accumulation and transport in nanostructured dye-sensitized solar cells with electrolyte or CuSCN as hole conductor  

Microsoft Academic Search

The charge transport properties of the dye-sensitized solar cells consisting of Ru(dcbpyH2)2(NCS)2-sensitized nanostructured TiO2 with either redox electrolyte or CuSCN as hole conductor have been compared. The electron transport time and the electron charge in the TiO2 varies in a similar way with the incident light intensity for both hole conductors: electron transport becomes faster and electron accumulation increases with

Boriss Mahrov; Anders Hagfeldt; Frank Lenzmann; Gerrit Boschloo

2005-01-01

405

Highly efficient photon-to-electron conversion with mercurochrome-sensitized nanoporous oxide semiconductor solar cells  

Microsoft Academic Search

Dye-sensitized solar cells based on nanoporous oxide semiconductor thin films such as TiO2, Nb2O5, ZnO, SnO2, and In2O3 with mercurochrome as the sensitizer were investigated. Photovoltaic performance of the solar cell depended remarkably on the semiconductor materials. Mercurochrome can convert visible light in the range of 400–600nm to electrons. A high incident photon-to-current efficiency (IPCE), 69%, was obtained at 510nm

Kohjiro Hara; Takaro Horiguchi; Tohru Kinoshita; Kazuhiro Sayama; Hideki Sugihara; Hironori Arakawa

2000-01-01

406

Low-temperature fabrication of dye-sensitized solar cells by transfer of composite porous layers  

Microsoft Academic Search

Dye-sensitized solar cells have established themselves as a potential low-cost alternative to conventional solar cells owing to their remarkably high power-conversion efficiency combined with `low-tech' fabrication processes. As a further advantage, the active layers consisting of nanoporous TiO2 are only some tens of micrometres thick and are therefore in principle suited for flexible applications. However, typical flexible plastic substrates cannot

Michael Dürr; Andreas Schmid; Markus Obermaier; Silvia Rosselli; Akio Yasuda; Gabriele Nelles

2005-01-01

407

Improving the performance of colloidal quantum-dot-sensitized solar cells  

Microsoft Academic Search

Solar cells based on a mesoporous structure of TiO2 and the polysulfide redox electrolyte were prepared by direct adsorption of colloidal CdSe quantum dot light absorbers onto the oxide without any particular linker. Several factors cooperate to improve the performance of quantum-dot-sensitized solar cells: an open structure of the wide bandgap electron collector, which facilitates a higher covering of the

Sixto Giménez; Iván Mora-Seró; Lorena Macor; Nestor Guijarro; Teresa Lana-Villarreal; Roberto Gómez; Lina J. Diguna; Qing Shen; Taro Toyoda; Juan Bisquert

2009-01-01

408

Biocompatible and freestanding anatase TiO2 nanomembrane with enhanced photocatalytic performance  

NASA Astrophysics Data System (ADS)

Biocompatible and freestanding TiO2 nanotube membranes with improved photocatalytic activity were fabricated through a water-vapour-assisted annealing treatment at relatively low temperatures. Photoluminescence results and structure characterization prove that the obtained TiO2 nanotube membranes not only possess an enhanced anatase crystallinity from water molecule-intermediated dissolution-precipitation reactions, but are also covered with abundant hydroxyl groups which are hardly influenced by external disturbances. The anatase crystallinity, the superficial hydroxyl groups and the nanotubular morphology of the membrane treated with water vapour thus lead to enhancement in photocatalytic activity. This new approach is simple and time-saving, opening up new opportunities in various areas, including tissue-engineering, watersplitting, dye-sensitized solar cells and photocatalysis.

Li, Menglin; Huang, Gaoshan; Qiao, Yuqin; Wang, Jiao; Liu, Zhaoqian; Liu, Xuanyong; Mei, Yongfeng

2013-08-01

409

Genotoxicity of citrus wastewater in prokaryotic and eukaryotic cells and efficiency of heterogeneous photocatalysis by TiO(2).  

PubMed

The presence of (±)?-pinene, (+)?-pinene, (+)3-carene, and R-(+)limonene terpenes in wastewater of a citrus transformation factory was detected and analyzed, in a previous study, by using Solid Phase Micro-extraction (SPME) followed by GC analyses. Purpose of that research was to compare the genotoxic responses of mixtures of terpenes with the genotoxicity of the individual compounds, and the biological effects of actual wastewater. Genotoxicity was evaluated in the Salmonella reversion assay (Ames test) and in V79 cells by Comet assay. Ames tests indicated that the four single terpenes did not induce an increase of revertants frequency. On the contrary, the mixtures of terpenes caused, in the presence of metabolic activation, a highly significant increase of the revertants in TA100 strain in comparison to the control. The Comet assay showed a significant increase in DNA damage in V79 cells treated for 1h with single or mixed terpenes. Moreover, the actual wastewater was found highly genotoxic in bacterial and mammalian cells. Photocatalytic tests completely photodegraded the pollutants present in aqueous wastewater and the initial high genotoxicity of samples of wastewater collected during the photocatalytic run, was completely lose in 3h of irradiation. PMID:22257631

Saverini, Marghereth; Catanzaro, Irene; Sciandrello, Giulia; Avellone, Giuseppe; Indelicato, Sergio; Marcì, Giuseppe; Palmisano, Leonardo

2012-03-01

410

Physiological effect of anatase TiO2 nanoparticles on Lemna minor.  

PubMed

Manufactured metal oxide nanoparticles (NPs) are being used on a large scale, and these particles will inevitably reach a body of water through wastewater and urban runoff. The ecotoxicological study of these NPs on hydrophyte is limited at present. Lemna minor was exposed to media with different concentrations of titanium dioxide (TiO(2)) NPs or bulk TiO(2) for 7 d. The changes in plant growth, chlorophyll, antioxidant defense enzymes (peroxidase [POD], catalase [CAT], and superoxide dismutase [SOD] activities), and malondialdehyde (MDA) content were measured in the present study. The particle size of TiO(2) NPs and the zeta potential of TiO(2) NPs and of bulk TiO(2) in the culture media were also analyzed to complementally study the toxicity of these materials on duckweed. The results showed that the effect of TiO(2) NPs on plant growth was more obvious than bulk TiO(2.) Titanium dioxide NPs stimulated plant growth in low concentrations, but inhibited plant growth at high concentrations. The POD, SOD, and CAT activity of Lemna minor increased when TiO(2) NP concentration was lower than 200 mg/L to eliminate accumulated reactive oxygen species in plant cells. The SOD activity decreased when the TiO(2) NP concentration was higher than 200 mg/L, and the plant cell membrane encountered serious damage from 500 mg/L TiO(2) NP concentration in the culture media. PMID:22760594

Song, Guanling; Gao, Yuan; Wu, Hao; Hou, Wenhua; Zhang, Chunyang; Ma, Huiquan

2012-09-01

411

End-group functionalization of poly(3-hexylthiophene) as an efficient route to photosensitize nanocrystalline TiO2 films for photovoltaic applications.  

PubMed

Bulk heterojunction (BHJ) and dye-sensitized solar cells (DSSCs) have seen increased popularity over recent years and each technology has experienced tremendous improvements in power conversion efficiencies (PCEs), reaching 8 and 12%, respectively. The two technologies have been on independent improvement pathways, and this work establishes a link between them by using the archetypical hole conductor (poly-3-hexylthiophene, P3HT) in BHJs as a sensitizer on TiO(2) for DSSC applications. Three polymers were synthesized and examined as potential TiO(2) sensitizers in DSSCs under AM1.5 solar radiation. Using Grignard metathesis, regioregular P3HT was synthesized then functionalized with either one or two cyanoacrylic acid linker moieties to bind to the TiO(2) surface. End-group modification resulted in minimal changes to the optical and electronic properties as compared to pristine P3HT. Cyclic voltammetry (CV) experiments at anodic potentials of adsorbed sensitizer quantified the amount of alkylthiophene adsorbed on the TiO(2), whereas under reductive sweeps, cyanoacrylic acid end-group binding was determined. CVs of each polymer indicated that loading was drastically different as compared to pristine P3HT with the lowest loading on TiO(2) and monofunctionalized P3HT exhibited the highest loading. The DSSCs showed power conversion efficiencies (PCEs) of 0.1%, 0.2 and 2.2% for the polymer-sensitized TiO(2) of the unfunctionalized, monofunctionalized and difunctionalized polymers, respectively. DSSCs were then subjected to electrochemical impedance spectroscopy (EIS) in the dark and under monochromatic light radiation. The large variance in performance for the functionalized-P3HT sensitizers is attributed to differences in the adsorption modes of sensitizer on the TiO(2) surface, which in the difunctionalized case limits electrolyte recombination and favors forward charge transfer reactions. PMID:21563756

Krüger, Robin A; Gordon, Terry J; Baumgartner, Thomas; Sutherland, Todd C

2011-06-01

412

Growing TiO2 nanowires on the surface of graphene sheets in supercritical CO2: characterization and photoefficiency  

NASA Astrophysics Data System (ADS)

Tremendous interest exists towards synthesizing nanoassemblies for dye-sensitized solar cells (DSSCs) using earth-abundant and -friendly materials with green synthetic approaches. In this work, high surface area TiO2 nanowire arrays were grown on the surface of functionalized graphene sheets (FGSs) containing -COOH functionalities acting as a template by using a sol-gel method in the green solvent, supercritical carbon dioxide (scCO2). The effect of scCO2 pressure (1500, 3000 and 5000 psi), temperature (40, 60 and 80?°C), acetic acid/titanium isopropoxide monomer ratios (HAc/TIP = 2, 4 and 6), functionalized graphene sheets (FGSs)/TIP weight ratios (1:20, 1:40 and 1:60 w/w) and solvents (EtOH, hexane) were investigated. Increasing the HAc/TIPweight ratio from 4 to 6 in scCO2 resulted in increasing the TiO2 nanowire diameter from 10 to 40 nm. Raman and high resolution XPS showed the interaction of TiO2 with the -COOH groups on the surface of the graphene sheets, indicating that graphene acted as a template for polycondensation growth. UV-vis diffuse reflectance and photoluminescence spectroscopy showed a reduction in titania’s bandgap and also a significant reduction in electron-hole recombination compared to bare TiO2 nanowires. Photocurrent measurements showed that the TiO2nanowire/graphene composites prepared in scCO2 gave a 5× enhancement in photoefficiency compared to bare TiO2 nanowires.