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1

Application of TiO2 with different structures in solar cells  

NASA Astrophysics Data System (ADS)

The application of TiO2-based devices is mainly dependent on their crystalline structure, morphology, size, and exposed facets. Two kinds of TiO2 with different structures, namely TiO2 pompons and TiO2 nanotubes, have been prepared by the hydrothermal method. TiO2 with different structures is characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), and Brunauer—Emmett—Teller (BET) surface area analysis. Solar cells based on poly(3-hexylthiophene) (P3HT) and TiO2 with different structures are fabricated. In the device ITO/TiO2/P3HT/Au, the P3HT is designed to act as the electron donor, and TiO2 pompons and TiO2 nanotubes act as the electron acceptor. The effects of the TiO2 structure on the performance of hybrid heterojunction solar cells are investigated. The device with TiO2 pompons has an open circuit voltage (Voc) of 0.51 V, a short circuit current (Jsc) of 0.21 mA/cm2, and a fill factor (FF) of 28.3%. Another device with TiO2 nanotubes has a Voc of 0.5 V, Jsc of 0.27 mA/cm2, and FF of 28.4%. The results indicate that the TiO2 nanotubes with a unidimensional structure have better carrier transport and light absorption properties than TiO2 pompons. Consequently, the solar cell based on TiO2 nanotubes has a better performance.

Zhang, Tian-Hui; Piao, Ling-Yu; Zhao, Su-Ling; Xu, Zheng; Wu, Qian; Kong, Chao

2012-11-01

2

Effect of plasma treatment with various gases on nanocrystalline TiO2 for dye-sensitized solar cell (DSSC)  

Microsoft Academic Search

Titanium dioxide (TiO2) photocatalyst with anatase phase has been extensively investigated for Dye-sensitized solar cell (DSSC). The chemical activation of OH group on TiO2 surface can provide valuable electron transfer from sensitizer dye to TiO2. The plasma treatment is suggested as improving hydrophilic property of nano-structured TiO2 surface, and has different effects on TiO2 surface depending on the gas to

Jumi Kim; Min Jae Sin; Hyung Jin Kim; Byungyou Hong

2010-01-01

3

TiO2 Nanowire dye-sensitized solar cells Fabricated by Hydrothermal Method  

Microsoft Academic Search

TiO2 nanowire dye-sensitized solar cells were fabricated by using hydrothermal method. The synthesizing of TiO2 nanowire\\/nanorod arrays directly on FTO substrate would cause a high conducting loss to solar cells. Through la minating a compact layer between FTO substrate and photonic anode layer, the conducting loss could be effectively prevented. Results indicated that using different concentration of titanium tetrabutoxide would

Yang Xu; Haoshuang Gu; Huating Xia; Mingzhe Hu

2011-01-01

4

High efficiency quantum dot heterojunction solar cell using anatase (001) TiO2 nanosheets.  

PubMed

This is the first report of using anatase TiO(2) nanosheets with exposed (001) facets in a high-efficiency PbS quantum dot/TiO(2) heterojunction solar cell. The TiO(2) nanosheets have higher conduction band, and surface energy compared to normal anatase (101) TiO(2) nanoparticles. This PbS QD/TiO(2) heterojunction solar cell produces power conversion efficiency of 4.7% which is one of the highest reported in literature. PMID:22508497

Etgar, Lioz; Zhang, Wei; Gabriel, Stefanie; Hickey, Stephen G; Nazeeruddin, Md K; Eychmüller, Alexander; Liu, Bin; Grätzel, Michael

2012-04-24

5

Electrospun TiO2 electrodes for dye-sensitized solar cells  

NASA Astrophysics Data System (ADS)

We report the new application of electrospun TiO2 fibres as an electrode for dye-sensitized solar cells (DSSCs). TiO2 fibre electrode was electrospun directly onto a conducting glass substrate from a mixture of titanium(IV) propoxide and poly(vinyl acetate) (PVAc) in dimethyl formamide. The TiO2 fibres are composed of one-dimensionally aligned nanofibrils about 20 nm thick with an islands-in-a-sea morphology, which was obtained from the phase separation of TiO2 gel and PVAc during the solidification process. The porous structure of the electrospun TiO2 electrode was found to be efficiently penetrated by a viscous polymer gel electrolyte. In order to improve the photocurrent generation, we treated the electrospun TiO2 electrode with TiCl4 aqueous solution. The rutile crystal was grown on the surface of anatase TiO2 fibres. An additional TiO2 layer increased the volume fraction of active materials, resulting in an increase of sensitizer adsorption. The energy conversion efficiency obtained from electrospun TiO2 electrodes with a PVDF-HFP gel electrolyte was over 90% of that from a liquid electrolyte system.

Song, Mi Yeon; Kim, Do Kyun; Ihn, Kyo Jin; Jo, Seong Mu; Kim, Dong Young

2004-12-01

6

Characterization and performance of TiO2-based solar cells  

Microsoft Academic Search

In this paper two different methods, doctor blade of a paste and glancing angle deposition (GLAD), have been used to fabricate layers of titanium dioxide for use in organic solar cells. Doctor blade TiO2 consists of a random network of nanocrystals with an average pore size of about 9 - 10nm. Controlled nanometre-scale columnar structures of TiO2 with column spacing

B. M. Henry; Z. Xie; H. Smith; K. R. Kirov; V. M. Burlakov; C. R. M. Grovenor; H. E. Assender; G. A. D. Briggs; P. L. Burn; Mitsuru Kano; Yusuke Tsukahara

2005-01-01

7

Hierarchically assembled one-dimensional TiO2 nanostructures: echinoid- and labyrinth-shaped TiO2 crystals for dye sensitized solar cell.  

PubMed

TiO2 nanostructures have been studied intensively for decades for their photocatalytic properties. Recently, several interesting TiO2 nanostructures with controlled surface facets or shapes were reported. However, systemic approaches to obtain designed nanostructures are still rare. Here, various hierarchical 1D TiO2 nanostructures, including TiO2 nanorods, echinoid-shaped TiO2, and labyrinth-structured TiO2, were fabricated by a one-pot hydrothermal process. Concentrated HCl was added to a solution having a Ti4+/H+ ratio that ranged from 1/4 to 1/8. The highly concentrated acid stabilized hydrolysis and hindered condensation, thereby balancing nucleation and growth of TiO2 nanostructures in the hydrothermal treatment step. Dye-sensitized solar cells prepared using the hierarchical 1D TiO2 nanostructures have shown higher photon to current conversion efficiency in the wavelength over 600 nm compared to those prepared with TiO2 nanoparticles. PMID:23035455

Cha, Seung I; Hwang, Kyu Hyun; Kim, Yuhyun; Seo, Sean Hee; Lee, Dong Yoon

2012-09-01

8

Dye-Sensitized Solar Cell with Photoanode Made with Polystyrene-Ball-Embedded TiO2 Pastes  

NASA Astrophysics Data System (ADS)

We report the effect of varying the concentration of polystyrene (PS) balls embedded in TiO2 paste during the fabrication of TiO2 photoanodes on the performance of dye-sensitized solar cells (DSSCs). We fabricated porous photoanodes using TiO2 pastes mixed with various concentrations of PS balls in aqueous solution. During the TiO2 sintering processes, the PS evaporated, leaving behind large cavities (>1 ?m) in the photoanodes. These cavities enhance the scattering of light, leading to improved absorption of light by N3 dyes. DSSC efficiency increases with the increase in PS ball concentration during TiO2 fabrication. As with classical devices, TiCl4 treatment of TiO2 and the use of a compact TiO2 layer both improve the cell efficiency of DSSC devices with our large-cavity TiO2 photoanodes.

Hsu, Yu-Ching; Wu, Tony Chang Chi; Cheng, I-Chun; Chen, Jian-Zhang; Yang, Mu-Rong

2011-06-01

9

Dye Sensitized Solar Cells Based on Free-standing TiO2 Nanotube  

NASA Astrophysics Data System (ADS)

Dye-sensitized solar cells based on free-standing TiO2 nanotube arrays as electrodes have been fabricated. It was shown that highly ordered vertically oriented TiO2 nanotube arrays offer a large surface area for adsorption of dye molecules or quantum dots and provide a direct pathway for fast electron transport. This cuts down carrier recombination and enhances photoconversion efficiency. TiO2 nanotube arrays were obtained by potentiostatic anodization of titanium foil in fluoride-based ehylene glycol electrolyte. TiO2 nanotube arrays can be detached from the titanium foil by chemical etching and annealed at high temperatures to obtain highly crystalline anatase phase without cracking, since there is no strain induced between TiO2 and Ti foil. Solar cells based on free-standing dye-sensitized solar cells reveal much higher overall efficiency than those with nanotubes attached to the Ti foil, due to the improved crystallinity and front side illumination. J. Phys. Chem. C 2009, 113, 6310--6314

Kim, Chaehyun; Delikanli, Savas; Perera, Samanthe; Zeng, Hao

2010-03-01

10

Enhanced efficiency of dye-sensitized TiO 2 solar cells (DSSC) by doping of metal ions  

Microsoft Academic Search

Doped TiO2 semiconductor powders were synthesized using Al and W as photovoltaic property-enhancing impurities. Al-doped TiO2 electrodes increased open-circuit voltage (Voc), but reduced short-circuit current (Isc). In contrast, W-doped TiO2 had an opposite effect. However, dye-sensitized solar cell efficiency fabricated with doped TiO2 was remarkably better than that of undoped TiO2. It seems that these phenomena were related to electrical

Kyung Hyun Ko; Young Cheol Lee; Young Jin Jung

2005-01-01

11

Tunable TiO2 Nanotube Arrays for Flexible Bio-Sensitized Solar Cells.  

National Technical Information Service (NTIS)

Highly ordered, free-standing titanium dioxide nanotube (TiNT) arrays have been of intense interest to the alternative energies field in recent years due to their barrier-free electron conduction pathway vs. TiO2 nanoparticles in dye-sensitized solar cell...

A. Giri J. J. Martin M. H. Griep S. G. Hirsch V. Rodriguez-Santiago

2012-01-01

12

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

13

Eosin yellowish dye sensitized TiO2 solar cell with PEG/PEO/LiI/I2 as electrolyte  

NASA Astrophysics Data System (ADS)

Eosin Yellowish dye sensitized TiO2 nanoparticles (NP) and nanowires (NW) are employed as photo anodes in dye sensitized solar cells with PEO/PEG/LiI/I2 as electrolyte. Material characterization by XRD and SEM confirms the formation of anatase phased TiO2 NP and NW. Effective quenching of UV emission in TiO2 NW than NP is a consequence of reduction in recombination rate, which directly favours for better solar conversion efficiency. The photovoltaic performance of TiO2 NW with an overall conversion efficiency of 0.31 % is better than NP, which is the outcome of improved electron transport in NW.

Kanmani, S. S.; Umapathy, S.; Ramachandran, K.

2012-06-01

14

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

PubMed Central

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

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

2012-01-01

15

Synthesis of TiO2 Nanotube by Hydrothermal Method and Application for Dye-Sensitized Solar Cell  

Microsoft Academic Search

The TiO2 nanotube was synthesized by a hydrothermal method dependent on temperature. TiO2 nanotube was coated on FTO glass by screen printing The TiO2 nanotube was increasing as autoclaving temperature. The dye-sensitized solar cells were fabricated using ruthenium (II)(N719) dye and electrolyte (). The crystalline structure and morphology were characterized by X-ray diffraction (XRD), and scanning electron microscopy (SEM). The

Chang Hyo Lee; Kyung Hwan Kim; Kyung Uk Jang; Sang Jun Park; Hyung Wook Choi

2011-01-01

16

PbS quantum dots embedded TiO2 nanofibers for dye-sensitized solar cells  

Microsoft Academic Search

We report a new type of dye-sensitized solar cells (DSSCs) fabricated using PbS quantum dots (QDs) embedded TiO2 fibers as the photoanodes. QDs have shown great potential as an efficient light absorbing material with very high extinction coefficient. However, to obtain an efficient photoinduced charge transfer from QDs to TiO2, a stable linker is needed to attach QDs to TiO2.

Prakash Joshi; Lifeng Zhang; Mahbube Siddiki; Hao Fong; Jing Li; David Galipeau; Qiquan Qiao

2009-01-01

17

Synthesis of TiO 2 submicro-rings and their application in dye-sensitized solar cell  

Microsoft Academic Search

In this paper, novel TiO2 submicro-rings were synthesized via potentiostatic anodization of titanium powder coated on transparent conducting oxide glass. The TiO2 submicro-rings film was characterized by SEM, XPS and 3D optical profiling. Accordingly, a possible growth mechanism of submicro-rings was discussed. The TiO2 submicro-rings based dye-sensitized solar cell (DSSC) with the film thickness of ca. 3.1?m was assembled and

Ming Li; Yong Liu; Hai Wang; Hui Shen

2011-01-01

18

Densely aligned rutile TiO2 nanorod arrays with high surface area for efficient dye-sensitized solar cells.  

PubMed

One-dimensional (1-D) TiO(2) nanorod arrays (NRAs) with large inner surface area are desired in dye-sensitized solar cells (DSSCs). So far, good performance of DSSCs based on 1-D rutile TiO(2) NRAs remains a challenge mainly owing to their low dye-loading ability resulting from the insufficient specific surface area of 1-D TiO(2) nanostructures. In this paper, densely aligned TiO(2) NRAs with tunable thickness were grown directly on transparent conductive fluorine-doped tin oxide (FTO) substrates by hydrothermal method, followed by a facile chemical etching route to further increase the specific surface area of the TiO(2) NRAs. The etching treatment leads to the split of TiO(2) nanorods into secondary nanorods with a reduced diameter, which markedly enlarges the inner surface area of the TiO(2) NRAs. The formation of 1-D rutile TiO(2) nanotube arrays (NTAs) is observed as well in the etched TiO(2) films. Finally, a DSSC efficiency of 5.94% was achieved by utilizing an etched TiO(2) NRA as the photoanode, which is so far the best DSSC efficiency that has been reported for the 1-D rutile TiO(2) NRA films. PMID:22899164

Lv, Miaoqiang; Zheng, Dajiang; Ye, Meidan; Sun, Lan; Xiao, Jing; Guo, Wenxi; Lin, Changjian

2012-08-17

19

Annealing effect on Sb2S3-TiO2 nanostructures for solar cell applications.  

PubMed

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. PMID:23421351

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

2013-02-19

20

Electrons in nanostructured TiO 2 solar cells: transport, recombination and photovoltaic properties  

Microsoft Academic Search

This review highlights several significant advancements in understanding of electron transport and recombination in dye-sensitized nanostructured TiO2 solar cells and the limitations that these processes impose on cell performance. The influences of the electrolyte composition, network morphology, defect structure, and light intensity on the electron transport dynamics are evaluated. Also assessed are evidences for and implications of the large, spatially

Arthur J. Frank; Nikos Kopidakis; Jao van de Lagemaat

2004-01-01

21

Influence of VB group doped TiO2 on photovoltaic performance of dye-sensitized solar cells  

NASA Astrophysics Data System (ADS)

Dye-sensitized solar cell with VB group (vanadium (V), niobium (Nb) and tantalum (Ta)) doped TiO2 prepared by hydrothermal method shows a higher photovoltaic efficiency compared with the undoped TiO2. All the VB doping shift the flat band potential positively and increase the doping density which is investigated by Mott–Schottky plot. The positive shift of flat band potential improves the driving force of injecting electron from the LUMO of dye to the conduction band of TiO2 and the photocurrent. On the other hand, the increase of doping density accelerates transfer rate of electrons in TiO2 than the un-doped, which is confirmed by intensity-modulated photocurrent. V-, Nb-, Ta-doped TiO2 exhibited photovoltaic performance with 7.80%, 8.33%, 8.18%, respectively, compared with that of the cells based on pure TiO2 (7.42%).

Liu, Jia; Duan, Yandong; Zhou, Xiaowen; Lin, Yuan

2013-07-01

22

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

NASA Astrophysics Data System (ADS)

Tailoring the architectures of spherical TiO2 aggregates is crucial to obtain superior photovoltaic properties and promote their application in dye-sensitized solar cells (DSSCs). Herein, we synthesized spherical TiO2 aggregates using different building units, including nanocrystallites, nanorods, nanosheets, and nanotubes, via a hydrothermal method, and studied the effect of the building units on the performances of DSSCs. The aggregates assembled by uniform nanosheet and nanotube building units were synthesized with the use of spherical TiO2 nanorod aggregates as titanium sources in an alkaline hydrothermal reaction. Compared with TiO2 nanoparticles, the spherical TiO2 aggregates possess higher surface area, more efficient light scattering ability, and better electron transport properties. Among the four types of spherical TiO2 aggregates; the nanorod, nanotube, and nanosheet aggregates demonstrate better electron transport properties than the nanocrystallite aggregates; the nanotube and nanosheet aggregates exhibit more efficient light scattering than the nanocrystallite and nanorod aggregates; and the nanotube aggregates show the highest surface area. Thus the DSSC based on nanotube aggregates exhibited the highest energy conversion efficiency of 7.48%, which is 16.0%, 9.7%, and 19.5% higher than those of the DSSCs based on the nanosheet, nanorod, and nanocrystallite aggregates, respectively.Tailoring the architectures of spherical TiO2 aggregates is crucial to obtain superior photovoltaic properties and promote their application in dye-sensitized solar cells (DSSCs). Herein, we synthesized spherical TiO2 aggregates using different building units, including nanocrystallites, nanorods, nanosheets, and nanotubes, via a hydrothermal method, and studied the effect of the building units on the performances of DSSCs. The aggregates assembled by uniform nanosheet and nanotube building units were synthesized with the use of spherical TiO2 nanorod aggregates as titanium sources in an alkaline hydrothermal reaction. Compared with TiO2 nanoparticles, the spherical TiO2 aggregates possess higher surface area, more efficient light scattering ability, and better electron transport properties. Among the four types of spherical TiO2 aggregates; the nanorod, nanotube, and nanosheet aggregates demonstrate better electron transport properties than the nanocrystallite aggregates; the nanotube and nanosheet aggregates exhibit more efficient light scattering than the nanocrystallite and nanorod aggregates; and the nanotube aggregates show the highest surface area. Thus the DSSC based on nanotube aggregates exhibited the highest energy conversion efficiency of 7.48%, which is 16.0%, 9.7%, and 19.5% higher than those of the DSSCs based on the nanosheet, nanorod, and nanocrystallite aggregates, respectively. Electronic supplementary information (ESI) available: Additional TEM and SEM images, XRD pattern, and N2 adsorption-desorption isotherms. See DOI: 10.1039/c3nr01767b

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

2013-08-01

23

Sb2S3 surface modification induced remarkable enhancement of TiO2 core/shell nanowries solar cells  

NASA Astrophysics Data System (ADS)

This study presents the fabrication of a novel dye-sensitized solar cell with Sb2S3-modified TiO2 nanowire (NW) arrays/TiO2 nanoparticles (NP) (TiO2(NWs)/TiO2(NPs)/Sb2S3) as the anodes and N719 dye as the sensitizer. A solar conversion efficiency of 4.91% at 1 sun illumination was achieved for the composite cell, which is markedly higher than the efficiency rates obtained using TiO2 and TiO2(NWs)/Sb2S3/TiO2(NPs) NW cells, calculated at 2.36% and 3.11%, respectively. The improved efficiency results from the large surface area of the NPs, as well as the expansion of the light absorption region and high absorption coefficient by Sb2S3 surface modification.

Meng, Xiuqing; Wang, Xiaozhou; Zhong, Mianzeng; Wu, Fengmin; Fang, Yunzhang

2013-05-01

24

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

NASA Astrophysics Data System (ADS)

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

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

2012-07-01

25

Rutile TiO2 nanorod array for high efficient dye sensitized solar cells  

NASA Astrophysics Data System (ADS)

1-D nanomaterial for solar cell photoanode applications has attracted considerable interests due to its superior carrier transport speed and high electron collection efficiency. In this work, a novel fabrication process has been developed to grow single crystalline rutile TiO2 nanorod array directly on the top of fluorine doped tin oxide (FTO) substrate for application as photoanode for dye-sensitized solar cells. The process involves multiple-step growth with the assistance of self-assembled monolayer (SAM). The SAM layer allows the growth in the axial direction and suppresses the growth in the radial direction of the TiO2 nanorods. This method presents the capability of extending the length of the nanorods without sacrificing the porosity of nanorod arrays. The long TiO2 nanorods with high porosity have been used to fabricate dye-sensitized solar cells, and the effect of the nanostructure of the nanorod arrays on the device performance has been studied. Short circuit current of nanorods obtained from multi-step growth has been boosted up to three times more than that of single-step grown nanorods.

Yang, Mengjin; Li, Wenzhi

2013-03-01

26

TiO2 nanotubes and their application in dye-sensitized solar cells.  

PubMed

The present article reviews the current status of using TiO(2) nanotubes in Grätzel-type, dye-sensitized solar cells and extends the overview with the latest results and findings. Critical factors in tube geometry (length, diameter, top morphology), crystal structure (amorphous, anatase, rutile) as well as factors affecting dye loading or electron mobility are addressed. The highest solar cell efficiencies today for pure nanotube systems reach approximately 4% while for some mixed systems, around 7% has been reported. For both systems significant room for enhancement is anticipated and some key points and strategies for improvement are outlined. PMID:20648363

Roy, Poulomi; Kim, Doohun; Lee, Kiyoung; Spiecker, Erdmann; Schmuki, Patrik

2009-12-04

27

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

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

2012-10-11

29

Synthesis and dye-sensitized solar cell performance of nanorods/nanoparticles TiO2 from high surface area nanosheet TiO2.  

PubMed

High surface area nanosheet TiO2 with mesoporous structure were synthesized by hydrothermal method at 130 degrees C for 12 h. The samples characterized by XRD, SEM, TEM, SAED, and BET surface area. The nanosheet structure was slightly curved and approximately 50-100 nm in width and several nanometers in thickness. The as-synthesized nanosheet TiO2 had average pore diameter about 3-4 nm. The BET surface area and pore volume of the sample were about 642 m(2)/g and 0.774 cm(3)/g, respectively. The nanosheet structure after calcinations were changed into nanorods/nanoparticles composite with anatase TiO2 structure at 300-500 degrees C (10-15 nm in rods diameter and about 5-10 nm in particles diameter). The solar energy conversion efficiency (eta) of the cell using nanorods/nanoparticles TiO2 (from the nanosheet calcined at 450 degrees C for 2 h) with mesoporous structure was about 7.08% with Jsc of 16.35 mA/cm(2), Voc of 0.703 V and ff of 0.627; while eta of the cell using P-25 reached 5.82% with Jsc of 12.74 mA/cm(2), Voc of 0.704 V, and ff of 0.649. PMID:17256316

Pavasupree, Sorapong; Ngamsinlapasathian, Supachai; Suzuki, Yoshikazu; Yoshikawa, Susumu

2006-12-01

30

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

NASA Astrophysics Data System (ADS)

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.

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

2013-05-01

31

Plasma treatment effect on dye-sensitized solar cell efficiency of hydrothermal-processed TiO2 nanorods.  

PubMed

Atmospheric plasma (AP) treatment was carried out on TiO2 nanorods (NRs) that were hydrothermally grown on F-doped SnO2 (FTO)/glass. The effects of AP treatment on the surface of the TiO2 NRs were investigated, where the treatment involved the use of the reactive gases H2, N2, and O2. The surface energy of AP-treated TiO2 NRs was about 1.5 times higher than that of untreated TiO2 NRs (364.3 mJ/m2). After AP treatment, the increase of the peak area ratios of the Ti2O3 and TiO2 peaks in the XPS spectra resulted in a decrease in the number of oxygen vacancies in the TiO2 NRs. The efficiency of a dye-sensitized solar cell (DSSC) based on the N2-plasma-treated TiO2 NRs, which was approximately 1.11%, was about 79% higher than that of a DSSC based on the untreated TiO2 NRs. PMID:22966701

Ahn, Kyun; Lee, Hyun-Uk; Jeong, Se-Young; Kim, Jong-Pil; Jin, Jong Sung; Ahn, Hyeong-Soo; Kim, Hong-Seung; Cho, Chae-Ryong

2012-07-01

32

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

2012-07-30

33

Performance of dye-sensitized solar cell based on nanocrystals TiO 2 film prepared with mixed template method  

Microsoft Academic Search

Highly efficient dye-sensitized solar cells were produced using high-crystalline TiO2 nanoparticles as a thin-film semiconductor prepared with a mixed template of copolymer F127 (poly(ethylene oxide)106-poly(propylene oxide)70-poly(ethylene oxide)106) and surfactant CTAB (cetyltrimethylammonium bromide) which allows access to larger surface area, smaller size and higher crystallinity TiO2 particles. The light-to-electricity conversion of the TiO2 film composed of nanocrystals with the size of

Jinting Jiu; Fumin Wang; Masaru Sakamoto; Jun Takao; Motonati Adachi

2005-01-01

34

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

35

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.

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

2013-01-01

36

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

PubMed

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

2013-10-21

37

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

NASA Astrophysics Data System (ADS)

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.

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

2013-10-01

38

Electrophoretically Deposited TiO2 Nanotube Light-Scattering Layers of Dye-Sensitized Solar Cells  

NASA Astrophysics Data System (ADS)

We report herein the enhanced light-to-electricity conversion efficiency of a dye-sensitized solar cell using a new bilayer structure of the TiO2 electrode. The bilayer structure consists of a light-absorbing TiO2 nanoparticle layer together with a light-scattering TiO2 nanotube layer formed upon. High aspect-ratio TiO2 nanotubes (?-TNTs) with a diameter of 20 nm were prepared via anodization of a Ti sheet in a perchloric acid solution, and the ?-TNT layer was electrophoretically deposited onto the sintered TiO2 nanoparticle layer. The light-scattering property of the ?-TNT layer was comparable to that of the commonly used TiO2 sub-micron nanoparticle layer. The ?-TNT layer provided a large surface area for dye-adsorption as well as an efficient transport pathway for photo-generated carriers. These effects allowed a higher incident photon-to-current efficiency of the bilayer TiO2 structure with the nanotube light-scattering layer over the whole spectral range relative to that with a sub-micron nanoparticle layer.

Nakayama, Keisuke; Kubo, Takaya; Nishikitani, Yoshinori

2008-08-01

39

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

40

A comparative study on TiO2 doped hybrid solar cells  

NASA Astrophysics Data System (ADS)

In this study, n-type titanium (IV) oxide (TiO2) and p-type poly (3-hexylthiophene-2,5-diyl) (P3HT) structured various photovoltaic (PV) devices have been produced onto indium tin oxide (ITO) coated glass substrates. For the economy and simplicity, spin coating and doctor blading deposition methods were used in normal atmospheric conditions. The effect of the device morphology on the efficiency of the solar cells was investigated by applying various morphologies such as classic and optimized p-n junctions, bulk heterojunction (BHJ) and sandwich structures, respectively. Electrical characterizations of the devices were obtained under AM 1.5 G (100 mW/cm2) solar illumination.

Özdal, Teoman; Hame?, Yakup; Aslan, Erdem

2012-04-01

41

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

PubMed

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

Xiang, Peng; Li, Xiong; Wang, Heng; Liu, Guanghui; Shu, Ting; Zhou, Ziming; Ku, Zhiliang; Rong, Yaoguang; Xu, Mi; Liu, Linfeng; Hu, Min; Yang, Ying; Chen, Wei; Liu, Tongfa; Zhang, Meili; Han, Hongwei

2011-11-24

42

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

NASA Astrophysics Data System (ADS)

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.

Xiang, Peng; Li, Xiong; Wang, Heng; Liu, Guanghui; Shu, Ting; Zhou, Ziming; Ku, Zhiliang; Rong, Yaoguang; Xu, Mi; Liu, Linfeng; Hu, Min; Yang, Ying; Chen, Wei; Liu, Tongfa; Zhang, Meili; Han, Hongwei

2011-11-01

43

Electrochemical impedance spectra of CdSe quantume dots sensitized nanocrystalline TiO 2 solar cells  

Microsoft Academic Search

Quantum dots sensitized nanocrystalline TiO2 solar cells (QDSSCs) are promising third-generation photovoltaic devices. In comparison with conventional dye-sensitized\\u000a solar cells (DSSCs), the efficiency of QDSSCs is still very low (about 3%). In this paper, the electrochemical impedance spectroscopy\\u000a technology has been adopted to investigate the quasi-Fermi level and the carrier dynamics of the colloidal CdSe QDs sensitized\\u000a TiO2 eletrode with

XueQing Xu; Gang Xu

2011-01-01

44

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

NASA Astrophysics Data System (ADS)

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

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

2013-06-01

45

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

46

Improvement in performances of dye-sensitized solar cell with SiO2-coated TiO2 photoelectrode.  

PubMed

The pure TiO2 and the nano-porous SiO2-coated TiO2 (STO) films were deposited on the FTO substrates by spray technique for the application of dye-sensitized solar cells (DSSCs). XRD pattern shows the pure TiO2 and STO films exhibits the same structure. We found that there is no much difference in dye absorption between the STO and the pure TiO2 films. The electrochemical impedance spectra reveal that insulating nature of the porous SiO2 increases surface resistance of the TiO2 film and supresses back transfer of the photogenerated electrons to the electrolyte. The field-emission scanning electron microscopy (FE-SEM) and energy dispersion X-ray spectroscopy (EDS) reveal that the surface morphology and the existence of SiO2 layer on the surface of the TiO2 films, respectively. The photoelectrochemical results show that the short-circuit photocurrent (J(SC)) increased from 16.73 mA cm(-2) to 18.31 mA cm(-2) and the open-circuit voltage (V(OC)) value changed from 0.71 V to 0.74 V for the STO films. The efficiency of cell has been greatly improved from 8.25 to 9.3%. PMID:22523998

Mohan, Varishetty Madhu; Shimomura, Masaru; Murakami, Kenji

2012-01-01

47

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

48

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

2013-09-05

49

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

2012-09-27

50

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

NASA Astrophysics Data System (ADS)

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.

Lee, Chang Hyo; Rhee, Seung Woo; Choi, Hyung Wook

2012-01-01

51

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.

2012-01-01

52

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

PubMed

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

Lee, Chang Hyo; Rhee, Seung Woo; Choi, Hyung Wook

2012-01-05

53

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

54

Nanostructured TiO2 and ZnO solar cells using CdS as sensitizer: Stability investigation  

Microsoft Academic Search

Exploring quantum dots or nano-sized particles of CdS as an alternative sensitizer for organic dye in dye sensitized solar cells have attracted great interest due to the high cost and the UV instability of the organic dye. In this work, a 2.46% (Voc=0.69 V, Jsc= 6.54 mA\\/cm2, F.F. = 0.55) CdS sensitized nanoparticle TiO2 solar cell is achieved under AM

Bo Wang; Lei L. Kerr

2010-01-01

55

Enhancement of TiO2 nanoparticle properties and efficiency of dye-sensitized solar cells using modifiers  

NASA Astrophysics Data System (ADS)

A low-temperature hydrothermal process developed to synthesizes titania nanoparticles with controlled size. We investigate the effects of modifier substances, urea, on surface chemistry of titania (TiO2) nanopowder and its applications in dye-sensitized solar cells (DSSCs). Treating the nanoparticles with a modifier solution changes its morphology, which allows the TiO2 nanoparticles to exhibit properties that differ from untreated TiO2 nanoparticles. The obtained TiO2 nanoparticle electrodes characterized by XRD, SEM, TEM/HRTEM, UV-VIS Spectroscopy and FTIR. Experimental results indicate that the effect of bulk traps and the surface states within the TiO2 nanoparticle films using modifiers enhances the efficiency in DSSCs. Under 100-mW cm-2 simulated sunlight, the titania nanoparticles DSSC showed solar energy conversion efficiency = 4.6 %, with V oc = 0.74 V, J sc = 9.7324 mA cm-2, and fill factor = 71.35.

Rashad, M. M.; Shalan, A. E.; Lira-Cantú, Mónica; Abdel-Mottaleb, M. S. A.

2013-04-01

56

Rough conical-shaped TiO2-nanotube arrays for flexible backilluminated dye-sensitized solar cells  

NASA Astrophysics Data System (ADS)

Conical-shaped anodic TiO2-nanotube (TiNT) arrays with length of a few tens of micrometer and rough tube walls were fabricated for use in flexible backilluminated dye-sensitized solar cells (DSSCs) which exhibited conversion efficiency of 4.3% under AM1.5 back side illumination. As compared to TiO2 nanoparticles/Ti-based DSSC, TiNT/Ti-based DSSC showed enhanced light-harvesting efficiency, rapid electron-transport rate, prolonged electron lifetime, and reduced dark current, leading to an increase in efficiency by ~30%.

Lin, Chin-Jung; Yu, Wen-Yueh; Chien, Shu-Hua

2008-09-01

57

Dye-sensitized solar cells based on nanocrystalline TiO2 films surface treated with Al3+ ions: photovoltage and electron transport studies.  

PubMed

Nanocrystalline TiO2 films, surface modified with Al3+, were manufactured by depositing a TiO2 suspension containing small amounts of aluminum nitrate or aluminum chloride onto conducting glass substrates, followed by drying, compression, and finally heating to 530 degrees C. Electrodes prepared with TiO2 nanoparticles coated with less than 0.3 wt % aluminum oxide with respect to TiO2 improved the efficiency of the dye sensitized solar cell. This amount corresponds to less than a monolayer of aluminum oxide. Thus, the Al ions terminate the TiO2 surface rather than form a distinct aluminum oxide layer. The aluminum ion surface treatment affects the solar cell in different ways: the potential of the conduction band is shifted, the electron lifetime is increased, and the electron transport is slower when aluminum ions are present between interconnected TiO2 particles. PMID:16853380

Alarcón, H; Boschloo, G; Mendoza, P; Solis, J L; Hagfeldt, A

2005-10-01

58

Influence of Yb-Doped Nanoporous TiO2 Films on Photovoltaic Performance of Dye-Sensitized Solar Cells  

NASA Astrophysics Data System (ADS)

Yb-doped TiO2 pastes with different Yb/TiO2 weight ratios are prepared in the sol-gel process to obtain dye-sensitized solar cells (DSCs). The nanocrystalline size of Yb-TiO2 becomes smaller and the lattice parameters change. Lattice distortion is observed and dark current is detected. It is found that a part of Yb existing as insulating oxide Yb2O3 state acts as barrier layers at the electrode-electrolyte interface to suppress charge recombination. A Yb-doped TiO2 electrode applied in DSCs leads to a higher open-circuit voltage and a higher fill factor. How the Yb-doped TiO2 films affect the photovoltaic response of DSCs is discussed.

Xu, Wei-Wei; Dai, Song-Yuan; Hu, Lin-Hua; Liang, Lin-Yun; Wang, Kong-Jia

2006-08-01

59

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

60

High-performance nanoporous TiO2/La2O3 hybrid photoanode for dye-sensitized solar cells.  

PubMed

An organic lanthanum solution was prepared and used for modifying the nanoporous TiO(2) photoanode for dye-sensitized solar cells (DSSCs). The preliminary characterization results demonstrate that La(2)O(3) was formed on the surface of the TiO(2) photoanodes. The X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) analyses suggest that La(3+) was introduced into the TiO(2) nanocrystalline, while, the scanning electron microscopy (SEM) and tunnelling electron microscopy (TEM) characterizations suggest that a thin La(2)O(3) layer forms on surface of the TiO(2) nanostructure. The La(2)O(3) layer is able to alleviate the electron recombination as a passivation layer. Though the slight decrease in surface areas were induced by the surface modification, the dye loading were maintained, which can be attributed to the formation of strong co-ordination bonding between the dye molecules and the lanthanide. The bonding can also facilitate the electron transfer between the dye molecules and TiO(2) conduction band. Consequently, the open circuit potential and short circuit current were boosted significantly and the overall energy conversion efficiency of the DSSCs was remarkably improved from 6.84% for the control film to 9.67% for the La(3+)-modified film. PMID:22324434

Yu, Hua; Xue, Bofei; Liu, Porun; Qiu, Jingxia; Wen, William; Zhang, Shanqing; Zhao, Huijun

2012-02-22

61

In situ growth of a ZnO nanowire network within a TiO(2) nanoparticle film for enhanced dye-sensitized solar cell performance.  

PubMed

ZnO nanowire networks featuring excellent charge transport and light scattering properties are grown in situ within TiO(2) films. The resultant TiO(2) /ZnO composites, used as photoanodes, remarkably enhance the overall conversion efficiency of dye-sensitized solar cells (DSSCs) by 26.9%, compared to that of benchmark TiO(2) films. PMID:22930471

Bai, Yang; Yu, Hua; Li, Zhen; Amal, Rose; Lu, Gao Qing Max; Wang, Lianzhou

2012-08-29

62

Achievement of 6.03% conversion efficiency of dye-sensitized solar cells with single-crystalline rutile TiO2 nanorod photoanode  

Microsoft Academic Search

The rutile TiO2 nanorods (RTNs) with the length of 40-130 nm and diameters approximately 8-15 nm, containing some 300-500 nm sized RTN aggregates and 6% of anatase TiO2 nanocrystals, were prepared by surfactant-assisted hydrothermal method. The dye-sensitized solar cell (DSC) based on the RTNs exhibited power conversion efficiency of 6.03%. As compared to P25 TiO2 based DSC, RTNs based DSC

Weiguang Yang; Farong Wan; Yali Wang; Chunhua Jiang

2009-01-01

63

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

NASA Astrophysics Data System (ADS)

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 R k (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.

Meen, Teen-Hang; Jhuo, Yi-Ting; Chao, Shi-Mian; Lin, Nung-Yi; Ji, Liang-Wen; Tsai, Jenn-Kai; Wu, Tien-Chuan; Chen, Wen-Ray; Water, Walter; Huang, Chien-Jung

2012-10-01

64

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.

2012-01-01

65

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

NASA Astrophysics Data System (ADS)

Crack-free TiO2 nanotube (NT) membranes were obtained by short time re-anodization of a sintered TiO2 NT array on Ti foil, followed by dilute HF etching at room temperature. The resulting freestanding TiO2 membranes were opaque with a slight yellow color having one end open and another end closed. The membranes were then fixed on transparent fluorine-tin-oxide glass using a thin layer of screen-printed TiO2 nanoparticles (NPs) as a binding medium. It was found that low temperature treatment of the resulting NT/NP film under appropriate pressure before sintering at 450 °C was critical for successful fixation of the NT membrane on the NP layer. The resulting films with open-ends of NT membranes facing the NP layer (open-ends down, OED, configuration) exhibited better interfacial contact between NTs and NPs than those with closed-ends facing the NP layer (closed-ends down, CED, configuration). The cells with an OED configuration exhibit higher external quantum efficiency, greater charge transfer resistance from FTO/TiO2 to electrolyte, and better dye loading compared to CED configurations. The solar cells with the OED configuration gave 6.1% energy conversion efficiency under AM1.5G condition when the commercial N719 was used as a dye and I - /I3 - as a redox couple, showing the promise of this method for high efficiency solar cells.

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

2011-07-01

66

Improved dye sensitized solar cell performance in larger cell size by using TiO2 nanotubes  

NASA Astrophysics Data System (ADS)

Typical dye sensitized solar cells (DSSCs) exhibit a severe reduction of power conversion efficiency when the cell size is increased. In order to cope with this issue, we have investigated the use of anodized TiO2 nanotubes on Ti foil in combination with the standard TiO2 nanoparticle paste coated anode structure. The presence of nanotubes in the anode structure enabled a significant mitigation of the size-dependent deterioration of the DSSC performance, with a trend of much milder decrease of the efficiency as a function of the cell dimension up to 9 cm2. The observed improvement is partly attributed to the elimination of fluorine-doped tin oxide glass in the anode structure, as well as the enhanced charge collection via the nanotube coated Ti substrate, resulting from enhanced mechanical and electrical connections and possibly improved light trapping. The introduction of TiO2 nanotubes on the Ti foil substrate led to a substantial improvement of the Jsc current density.

Zhang, Yanyan; Khamwannah, Jirapon; Kim, Hyunsu; Noh, Sun Young; Yang, Haibin; Jin, Sungho

2013-02-01

67

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

68

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

2013-10-09

69

Quantum dot photoelectrochemical solar cells based on TiO 2 -SrTiO 3 heterostructure nanotube array scaffolds  

Microsoft Academic Search

Titania-Strontium titanate (TiO2-SrTiO3) nanotube array with heterostructure has been demonstrated as an efficient scaffold applied to quantum dot photoelectrochemical\\u000a solar cells. Quantum dot CdS serviced as solar light absorbent is chosen as an example to illustrate superior performance\\u000a and deposited on scaffolds by successive ionic layer adsorption and reaction (SILAR) technique. The photoelectro-chemical\\u000a performance of such solar cell is strongly

Jun Zhang; Chengchun Tang

2011-01-01

70

A new polymeric photosensitizer for dye-sensitized solar cell with porous TiO 2 from forest carbon resources  

Microsoft Academic Search

A series of new lignin derivatives (lignophenols) containing phenol, p-cresol, catechol, resorcinol and pyrogallol synthesized from Hinoki (Chamaecyparis obtusa) and Douglas fir (Pseudotsuga menziessi) as softwood and beech (Fagas crenata) as hardwood was investigated as sensitizers for a dye-sensitized solar cell (DSSCs) of porous TiO2 under the irradiation of 150W Xe lamp. For example, LPs–DSSCs of hinoki-ligno-p-cresol, directly derived from

Mitsuru Aoyagi; Masamitsu Funaoka

2004-01-01

71

Fabrication of dye-sensitized solar cell (DSSC) using different particle sizes of TiO2 deposited via nano-particle deposition system (NPDS).  

PubMed

TiO2 layers were fabricated using a nano-particle deposition system (NPDS) on transparent conductive oxide (TCO) glass for dye sensitized solar cells (DSSCs). Conventionally, TiO2 paste for working electrodes has been fabricated using paste type methods. The fabricated paste composed of a mixture of nano-sized TiO2 powders, binders and solutions is then painted on TCO glass. After drying, the TiO2 layer on TCO glass is sintered to make a path for electron transfer. TiO2 layers formed by this paste type method require numerous steps, which can be time consuming. In this study, TiO2 powders were sprayed directly on TCO glass using NPDS in order to simplify the fabrication steps. To improve porosity and produce scattering layers, commercial nanocrystalline TiO, powders with different sizes were alternately deposited. Moreover, powders with different sizes were mixed and deposited on the TCO glass. The results indicate that the DSSCs with a TiO2 layer composed of different particle sizes had better cell performance than the cells assembled with single-sized TiO2 particles. Therefore, this study shows that a dry TiO2 coating process is possible for DSSC fabrication to improve its cell efficiencies, and this method can easily be applied on flexible substrates since NPDS is a room-temperature deposition process. PMID:22849150

Kim, Yang-Hee; Kim, Kwang-Su; Lee, Jin-Woong; Kim, Min-Saeng; Choi, Jung-Oh; Ahn, Sung-Hoon; Lee, Caroline Sunyong

2012-04-01

72

Achievement of 4.51% conversion efficiency using ZnO recombination barrier layer in TiO2 based dye-sensitized solar cells  

NASA Astrophysics Data System (ADS)

The authors report the use of chemically deposited ZnO recombination barrier layer for improved efficiency of TiO2 based dye-sensitized solar cells. The ZnO layers of different thicknesses were deposited on spin coated porous TiO2. The presence of ZnO over TiO2 was confirmed by x-ray diffraction, electron dispersive x-ray analysis, and supported by x-ray photoelectron spectroscopy, proved inherent energy barrier between the porous TiO2 electrode and lithium iodide electrolyte. They found that TiO2 based dye-sensitized solar cell with 30 nm ZnO layer thickness showed 4.51% efficiency due to the formation of efficient recombination barrier at electrode/electrolyte interface. Further increase in ZnO barrier thickness may leak the electrons injected from the dye due to its low electron effective mass of 0.2me.

Roh, Seung-Jae; Mane, Rajaram S.; Min, Sun-Ki; Lee, Won-Joo; Lokhande, C. D.; Han, Sung-Hwan

2006-12-01

73

Electrophoretically deposited TiO2 compact layers using aqueous suspension for dye-sensitized solar cells.  

PubMed

TiO2 compact layers (CLs) prepared by electrophoretic deposition (EPD) from an aqueous nanoparticle suspension were used in dye-sensitized solar cells (DSSCs) to prevent charge recombination at the interface between the transparent fluorine-doped tin oxide (FTO) substrate and the electrolyte. The TiO2 nanopowder (ca. 4.5 nm diameter) suspension used in the EPD process was prepared via a continuous hydrothermal flow synthesis pilot plant (at a production rate of ca. 0.38 kg h(-1)). The optimal thickness of the TiO2 CL for DSSCs is about 115 nm. Compared to the DSSCs without a CL, the optimal cell has shown improved short-circuit current density (JSC) and solar energy conversion efficiency by 13.1% and 15.0%, respectively. The mechanism for improved performance has been studied by the measurements of dark current and electrochemical impedance spectra. The interfacial charge transfer resistance at the FTO/electrolyte interface is increased after fabricating a CL in the cell, indicating inhibited electron recombination at the interface. PMID:23903769

Li, Xuemin; Qiu, Yin; Wang, Shasha; Lu, Shan; Gruar, Robert I; Zhang, Xuehua; Darr, Jawwad A; He, Tao

2013-09-21

74

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

PubMed

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

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

2012-04-01

75

Incorporation of graphenes in nanostructured TiO(2) films via molecular grafting for dye-sensitized solar cell application.  

PubMed

This paper presents a systematic investigation on the incorporation of chemical exfoliation graphene sheets (GS) in TiO(2) nanoparticle films via a molecular grafting method for dye-sensitized solar cells (DSSCs). By controlling the oxidation time in the chemical exfoliation process, both high conductivity of reduced GS and good attachment of TiO(2) nanoparticles on the GS were achieved. Uniform GS/TiO(2) composite films with large areas on conductive glass were prepared by electrophoretic deposition, and the incorporation of GS significantly improved the conductivity of the TiO(2) nanoparticle film by more than 2 orders of magnitude. Moreover, the power conversion efficiency for DSSC based on GS/TiO(2) composite films is more than 5 times higher than that based on TiO(2) alone, indicating that the incorporation of GS is an efficient means for enhancing the photovoltaic (PV) performance. The better PV performance of GS/TiO(2) DSSC is also attributed to the better dye loading of GS/TiO(2) film than that of TiO(2) film. The effect of GS content on the PV performances was also investigated. It was found that the power conversion efficiency increased first and then decreased with the increasing of GS concentration due to the decrease in the transmittance at high GS content. Further improvements can be expected by fully optimizing fabrication conditions and device configuration, such as increasing dye loading via thicker films. The present synthetic strategy is expected to lead to a family of composites with designed properties. PMID:20455548

Tang, Yong-Bing; Lee, Chun-Sing; Xu, Jun; Liu, Zeng-Tao; Chen, Zhen-Hua; He, Zhubing; Cao, Yu-Lin; Yuan, Guodong; Song, Haisheng; Chen, Limiao; Luo, Linbao; Cheng, Hui-Ming; Zhang, Wen-Jun; Bello, Igor; Lee, Shuit-Tong

2010-06-22

76

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.

2013-01-01

77

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

NASA Astrophysics Data System (ADS)

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.

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

2013-01-01

78

Directly Determine an Additive-Induced Shift in Quasi-Fermi Level of TiO2 Films in Dye-Sensitized Solar Cells  

NASA Astrophysics Data System (ADS)

The shifts in quasi-Fermi level (QFL) of TiO2 films affected by additives are directly measured using three-electrode dye-sensitized solar cells (DSCs). The difference in QFL of TiO2 under short circuit and open circuit are also analyzed. It is found that the QFL difference between the electrolyte side of the TiO2 film and the equilibrium redox potential, as well as the QFL difference between the two sides of the TiO2 film shift to higher potential owing to the addition of TBP to the electrolyte. The shift values are influenced by the cations present in the electrolyte. These directly determined changes in QFL in TiO2 films both under open circuit and short circuit may provide valuable information for studying DSC operation mechanisms such as the dynamics of charge separation and charge recombination processes.

Zhang, Shufang; Yanagida, Masatoshi; Yang, Xudong; Han, Liyuan

2012-10-01

79

Structure and dye-sensitized solar cell application of TiO2 nanotube arrays fabricated by the anodic oxidation method  

NASA Astrophysics Data System (ADS)

Well-ordered TiO2 nanotube arrays were fabricated by the potentiostatic anodic oxidation method using pure Ti foil as a working electrode and ethylene glycol solution as an electrolyte with the small addition of NH4F and H2O. The influence of anodization temperature and time on the morphology and formation of TiO2 nanotube arrays was examined. The TiO2 nanotube arrays were applied as a photoelectrode to dye-sensitized solar cells. Regardless of anodizing temperature and time, the average diameter and wall thickness of TiO2 nanotube arrays show a similar value, whereas the length increases with decreasing reaction temperature. The conversion efficiency is very low, which is due to a morphology breaking of the TiO2 nanotube arrays in the manufacturing process of a photoelectrode.

Ok, Seon-Yeong; Cho, Kwon-Koo; Kim, Ki-Won; Ryu, Kwang-Sun

2010-05-01

80

Preparation and properties of a phthalocyanine-sensitized TiO2 nanotube array for dye-sensitized solar cells  

NASA Astrophysics Data System (ADS)

Dye-sensitized solar cells (DSSCs) based on an ordered titanate nanotube (TNT) array were fabricated using phthalocyanine as a dye sensitizer. The ordered TNT photoanode was prepared via two steps: (1) electrosynthesis of the TiO2 nanotube array in the HF solution by the anodization method; (2) electrodeposition of 2,9,16,23-tetra-amino zinc phthalocyanine (TAZnPc) in the TiO2 nanotubes array. The morphological characteristics and structures of TAZnPc immobilized TiO2 NTs (TAZnPc/TiO2 NTs) were examined. The average pore diameter of the TNT structures was 100 nm and its average length was 500 nm. The diffuse reflection spectra (DRS) curves of TAZnPc/TiO2 NTs had a wide absorption at 550-950 nm, which may come from the TAZnPc. The photocurrent and photovoltage of the cells were measured with an active area of 0.25 cm2 by using CHI660B electrochemical workstation in the condition of illumination (AM 1.5, 100 mW cm-2). The open circuit voltage (Voc), short circuit current (Jsc) and fill factor (FF) of the DSSC are 0.416 V, 0.115 mA cm-2 and 0.68, respectively.

Cheng, Wanxi; Shen, Yue; Wu, Guizhi; Gu, Feng; Zhang, Jiancheng; Wang, Linjun

2010-12-01

81

Hydrothermal Synthesis of a Crystalline Rutile TiO2 Nanorod Based Network for Efficient Dye-Sensitized Solar Cells.  

PubMed

One-dimensional (1D) TiO2 nanostructures are desirable as photoanodes in dye-sensitized solar cells (DSSCs) due to their superior electron-transport capability. However, making use of the DSSC performance of 1D rutile TiO2 photoanodes remains challenging, mainly due to the small surface area and consequently low dye loading. Herein, a new type of photoanode with a three-dimensional (3D) rutile-nanorod-based network structure directly grown on fluorine-doped tin oxide (FTO) substrates was developed by using a facile two-step hydrothermal process. The resultant photoanode possesses oriented rutile nanorod arrays for fast electron transport as the bottom layer and radially packed rutile head-caps with an improved large surface area for efficient dye adsorption. The diffuse reflectance spectra showed that with the radially packed top layer, the light-harvesting efficiency was increased due to an enhanced light-scattering effect. A combination of electrochemical impedance spectroscopy (EIS), dark current, and open-circuit voltage decay (OCVD) analyses confirmed that the electron-recombiantion rate was reduced on formation of the nanorod-based 3D network for fast electron transport. As a resut, a light-to-electricity conversion efficiency of 6.31?% was achieved with this photoanode in DSSCs, which is comparable to the best DSSC efficiencies that have been reported to date for 1D rutile TiO2 . PMID:23939704

Yu, Hua; Pan, Jian; Bai, Yang; Zong, Xu; Li, Xinyong; Wang, Lianzhou

2013-08-12

82

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

2012-01-25

83

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

NASA Astrophysics Data System (ADS)

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.

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

2013-10-01

84

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

2013-09-17

85

Surface modified TiO2 nanostructure with 3D urchin-like morphology for dye-sensitized solar cell application.  

PubMed

Three-dimensional (3D) urchin-like rutile TiO2 powders were synthesized by a mild hydrothermal method without any templates. An individual urchin-like TiO2 powder consists of self-assembled nanorods with a length of about 150 nm and width of about 10 nm. Additionally, the urchin-like TiO2 nanopowders were coated with an ultra-thin ZnO layer in order to modify the surface properties of the nanopowders, and the ZnO layer was confirmed by high-resolution transmission electron microscopy (HRTEM) and X-ray photoelectron spectroscopy (XPS) analysis. The ZnO-modified TiO2 was used as a photoelectrode of a dye-sensitized solar cell (DSSC) and the solar cell performances were investigated. In comparison with bare TiO2, ZnO-modified TiO2 improved the photovoltaic performances, i.e., energy conversion efficiency, open circuit voltage, and short circuit current were increased. The higher DSSC performance of ZnO-modified TiO2 was attributed to its higher dye loading and lower charge recombination rate. PMID:22629944

Shin, Seong Sik; Kim, Dong Wook; Lee, Sangwook; Cho, In-Sun; Kim, Dong Hoe; Park, Jong Hoon; Hong, Kug Sun

2012-02-01

86

First Demonstration of Surface Passivation in Dye-Sensitized TiO2 Solar Cells by an Additive in the Electrolyte  

SciTech Connect

The composition of the electrolyte is known to greatly influence the performance of dye-sensitized solar cells. It has been speculated that some components of the electrolyte passivate the TiO2 surface against recombination; however, this has never been confirmed experimentally. We hereby present the first case of passivation of the TiO2 surface against recombination by an additive in the electrolyte. Even though the additive also causes a downward movement of the TiO2 bands, suppression of recombination prevails and an overall improvement in open-circuit photovoltage is observed. This work was conducted in collaboration with the DOE Office of Science program.

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

2005-01-01

87

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

SciTech Connect

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

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

2000-01-01

88

CLASSICAL AREAS OF PHENOMENOLOGY: Light scattering of nanocrystalline TiO2 film used in dye-sensitized solar cells  

NASA Astrophysics Data System (ADS)

This paper studies the light scattering and adsorption of nanocrystalline TiO2 porous films used in dye-sensitized solar cells composed of anatase and/or rutile particles by using an optical four-flux radiative transfer model. These light properties are difficult to measure directly on the functioning solar cells and they can not be calculated easily from the first-principle computational or quantitative theoretical evaluations. These simulation results indicate that the light scattering of 1-25 nm TiO2 particles is negligible, but it is effective in the range of 80 and 180 nm. A suitable mixture of small particles (10 nm radius), which are resulted in a large effective surface, and of larger particles (150 nm radius), which are effective light scatterers, have the potential to enhance solar absorption significantly. The rutile crystals have a larger refractive index and thus the light harvest of the mixtures of such larger rutile and relatively small anatase particles is improved in comparison with that of pure anatase films. The light absorption of the 10 ?m double-layered films is also examined. A maximal light absorption of double-layered film is gotten when the thickness of the first layer of 10 nm-sized anatase particles is comparable to that of the second larger rutile layer.

Xiong, Bi-Tao; Zhou, Bao-Xue; Bai, Jing; Zheng, Qing; Liu, Yan-Biao; Cai, Wei-Min; Cai, Jun

2008-10-01

89

Sputter deposition and surface treatment of TiO 2 films for dye-sensitized solar cells using reactive RF plasma  

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 indium tin oxide (ITO) coated glass 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 600 W and substrate temperature of 400 °C were

Youl-Moon Sung; Hee-Je Kim

2007-01-01

90

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

Microsoft Academic Search

A versatile anodization method was reported to anodize Ti wires into cylindrical core-shell-like and thermally crystallized TiO2 nanotube (TNT) arrays that can be directly used as the photoanodes for semi- and all-solid fiber-type dye-sensitized solar cells (F-DSSC). Both F-DSSCs showed higher power conversion efficiencies than or competitive to those of previously reported counterparts fabricated by depositing TiO2 particles onto flexible

Jiefeng Yu; Dan Wang; Yining Huang; Xing Fan; Xin Tang; Cong Gao; Jianlong Li; Dechun Zou; Kai Wu

2011-01-01

91

Fabrication of CdSe Nano-Tetrapod Sensitized TiO2 Nanotube Arrays for Quantum Dot-Sensitized Solar Cell Applications  

Microsoft Academic Search

Nano-tetrapods Cadmium Selenide (CdSe) quantum dots (QDs) have been prepared and exploited as inorganic dyes to sensitize a large-band-gap TiO2 nanotube array layer for QD-sensitized solar cells. Covering the TiO2 films with QDs has been achieved using two strategies: (i) direct adsorption from chloroform dispersions and (ii) anchoring the QDs through a molecular linker 3-mercaptopropionic acid (MPA). In contrast with

Qi Pang; Limin Leng; Chunjie Liang; Jun He; Liya Zhou; Yuwei Lan; Lijuan Zhao

2012-01-01

92

Dye-sensitized solar cell based on optically transparent TiO 2 nanocrystalline electrode prepared by atomized spray pyrolysis technique  

Microsoft Academic Search

Preparation of crack-free thin films of interconnected and non-agglomerated TiO2 nanoparticles on electronically conducting fluorine doped tin oxide surfaces is instrumental in designing and developing transparent dye-sensitized solar cells (DSCs). A novel technique called “Atomized Spray Pyrolysis” (ASP) has been designed and developed to achieve such perfectly transparent thin films. Optical transmittance of TiO2 films produced on FTO surface by

H. M. N. Bandara; R. M. G. Rajapakse; K. Murakami; G. R. R. A. Kumara; G. Anuradha Sepalage

2011-01-01

93

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

NASA Astrophysics Data System (ADS)

Funnel-structured TiO2 electrode is fabricated by three-beam laser interference.This method is based on the laser-induced melting and agglomeration of TiO2 nanoparticles.The funnel cell exhibits much higher current density and efficiency than the reference one.

Jin, Minhea; Lee, Myeongkyu

2013-10-01

94

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

NASA Astrophysics Data System (ADS)

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

Ahmadian, Radin

2010-08-01

95

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

96

Compact packing of CdS nanoparticle in flower like TiO2 nanorods for DSSC solar cell  

Microsoft Academic Search

Crystalline TiO2 nanorod was grown into flower like structure on ITO surface by hydrothermal method. CdS nanoparticles prepare from the precursor cadmium acetate and sodium sulfide and particle size control by varying concentration of Thioglycolic acid (TGA). These nanoparticles are farther embedded on TiO2 nanorod surface by chemical bath deposition. The behavior of film will further used for DSSC solar

Mrinmoy Misra; Madan Lal Singla; Pawan Kapur; C. Ghansyam

2012-01-01

97

Effects of TiO2 structures in dye-sensitized solar cell.  

PubMed

In this work, the effects of crystalline structure of the TiO2, which is incorporated in fabrication of the n-type electrode, on the DSSC performance were investigated in terms of the energy conversion efficiency. In this effort, TiO2 nanoparticle pastes with varying contents of rutile and anatase structures were prepared by using the ethanol mixing method. The most efficient photo-electro-chemical performance was achieved for the DSSC fabricated with the TiO2 paste in which the anatase form of the nanocrystal extends to 90%. PMID:21456225

Kim, Bok-Min; Rho, Seon-Gyun; Kang, Choon-Hyoung

2011-02-01

98

The effect of substrate temperature on the spray-deposited TiO2 nanostructured films for dye-sensitized solar cells.  

PubMed

The nanostructured TiO2 films have deposited on SnO2:F (FTO) coated glass substrate by spray pyrolysis technique at different substrate temperatures of 200-500 degrees C. The structural, surface morphological and optical properties of TiO2 films significantly vary with the substrate temperature. The surface of the TiO2 films deposited at 400 degrees C shows the nanoflakes and short nanorods (approximately 130 nm) like structures while the TiO2 films prepared at 500 degrees C shows only the nanoflakes like structures. The band gap of the TiO2 films prepared at higher temperatures (300-500 degrees C) becomes narrow due to presence the rutile phases in their crystal structure. Ruthenium (II) complex as a dye, KI/I2 as an electrolyte and carbon on FTO glass as a counter electrode has used to fabricate the dye-sensitized solar cell (DSC). The TiO2 film deposited at 400 degrees C has showed the best photovoltaic performance in DSC with the efficiency of 3.81%, the photovoltage of 773 mV, the photocurrent of 8.34 mA/cm2, and the fill factor of 56.17%. The photovoltage of the DSC increases with the increase of substrate temperature during the deposition of TiO2 films. Moreover, all the DSCs exhibit reasonably high fill factor value. PMID:21776690

Hossain, Md Faruk; Takahashi, Takakazu

2011-04-01

99

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

100

Reduced electron recombination of dye-sensitized solar cells based on TiO2 spheres consisting of ultrathin nanosheets with [001] facet exposed  

PubMed Central

Summary An anatase TiO2 material with hierarchically structured spheres consisting of ultrathin nanosheets with 100% of the [001] facet exposed was employed to fabricate dye-sensitized solar cells (DSCs). Investigation of the electron transport and back reaction of the DSCs by electrochemical impedance spectroscopy showed that the spheres had a threefold lower electron recombination rate compared to the conventional TiO2 nanoparticles. In contrast, the effective electron diffusion coefficient, D n, was not sensitive to the variation of the TiO2 morphology. The TiO2 spheres showed the same D n as that of the nanoparticles. The influence of TiCl4 post-treatment on the conduction band of the TiO2 spheres and on the kinetics of electron transport and back reactions was also investigated. It was found that the TiCl4 post-treatment caused a downward shift of the TiO2 conduction band edge by 30 meV. Meanwhile, a fourfold increase of the effective electron lifetime of the DSC was also observed after TiCl4 treatment. The synergistic effect of the variation of the TiO2 conduction band and the electron recombination determined the open-circuit voltage of the DSC.

Liu, Meinan; Yan, Cheng; Bell, John

2012-01-01

101

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

2010-07-30

102

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

NASA Astrophysics Data System (ADS)

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 TiO2 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. TiO2 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 TiO2. Electron microscopy analysis and impedance measurements showed that a thin continuous TiO2 layer is formed at the interface as a result of the local melting of TiO2 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 TiO2 paste revealed an efficiency improvement from ? = 3.3% to 5.4%, and an increase from 8.2% to 11.2% was achieved with the TiO2 electrodes made from a commercial paste.

Kim, Jinsoo; Kim, Jonghyun; Lee, Myeongkyu

2010-08-01

103

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

104

TiO2 nanowire sensitized by natural dyes for solar cell applications  

NASA Astrophysics Data System (ADS)

We investigate the electronic coupling between a semiconductor TiO2 nanowire and a natural dye sensitizer based on time-dependent first-principles calculations. The model dye molecule, cyanidin is found to dissociate into the quinonoidal form upon adsorption, rendering its highest occupied molecular orbitals (HOMO) located in the middle of TiO2 bandgap and its lowest-unoccupied molecular orbital (LUMO) at the bottom of TiO2 conduction band. The visible light absorption is greatly enhanced with two prominent peaks at 460 nm and 650 nm. The excited electrons are injected into the TiO2 conduction within a ultrafast timescale of <50 fs, with negligible non-radiative energy dissipation and recombination.

Meng, Sheng; Ren, Jun; Kaxiras, Efthimios

2008-03-01

105

Nanostructure control of graphene-composited TiO2 by a one-step solvothermal approach for high performance dye-sensitized solar cells  

NASA Astrophysics Data System (ADS)

We present a one-step solvothermal approach to prepare uniform graphene-TiO2 nanocomposites with delicately controlled TiO2 nanostructures, including ultra-small 2 nm nanoparticles, 12 nm nanoparticles and nanorods. Using three composites as photoanode materials, the effect of nanostructure of graphene-composited TiO2 on the performance of dye-sensitized solar cells was investigated, and results showed that the ultra-small 2 nm TiO2-graphene composite based photoanode exhibited the highest power conversion efficiency of 7.25%.We present a one-step solvothermal approach to prepare uniform graphene-TiO2 nanocomposites with delicately controlled TiO2 nanostructures, including ultra-small 2 nm nanoparticles, 12 nm nanoparticles and nanorods. Using three composites as photoanode materials, the effect of nanostructure of graphene-composited TiO2 on the performance of dye-sensitized solar cells was investigated, and results showed that the ultra-small 2 nm TiO2-graphene composite based photoanode exhibited the highest power conversion efficiency of 7.25%. Electronic supplementary information (ESI) available: Detailed experimental procedures, AFM images, SEM images, J-V curves for optimization, and tables containing EDX results, BET results and calculation data. See DOI: 10.1039/c1nr11300c

He, Ziming; Guai, Guanhong; Liu, Jing; Guo, Chunxian; Chye Loo, Joachim Say; Li, Chang Ming; Tan, Timothy Thatt Yang

2011-11-01

106

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

107

Controlled fabrication of TiO2 rutile nanorod/anatase nanoparticle composite photoanodes for dye-sensitized solar cell application.  

PubMed

We present a straightforward procedure to prepare composite photoanodes which consisted of TiO2 rutile nanorods/anatase nanoparticles synthesized under hydrothermal conditions, with the ratio of rutile to anatase controlled simply by adjusting the volume of nitric acid. The as-prepared TiO2 composites exhibited high specific surface area, light-scattering effect, and good crystallinity. The dye-sensitized solar cells (DSCs) using the TiO2 composites showed higher short-circuit photocurrent and overall conversion efficiency than the DSC from pure-anatase nanoparticles. The highest conversion efficiency was achieved from the DSC based on TiO2 nanocomposites with 24 wt% rutile nanorods, which was attributed to improved light harvesting caused by the enhancement of specific surface area and scattering effect from rutile nanorods. PMID:21597134

Peng, Wenqin; Yanagida, Masatoshi; Han, Liyuan; Ahmed, Shahat

2011-05-20

108

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

109

Efficient carbon-doped nanostructured TiO 2 (anatase) film for photoelectrochemical solar cells  

Microsoft Academic Search

In this paper, we have demonstrated that carbon-doped nanostructured TiO2 (CD ns-TiO2) films could be prepared simply and cheaply with oxalic acid and tetrabutylammonium bromide (Bu4N·Br) as the carbon sources. The surface morphology of the films was a multiple-porous network structure.The average size\\u000a of nanoparticle was about 40 nm. Carbon doped into substitutional sites of TiO2 has also proven to be

Daobao Chu; Ximei Yuan; Guoxu Qin; Mai Xu; Peng Zheng; Jia Lu; Longwu Zha

2008-01-01

110

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).

2012-01-01

111

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

PubMed

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

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

2012-02-02

112

Study on TiO2 film for dye-sensitized solar cell using natural dyes  

Microsoft Academic Search

In this study, natural raw dyes extracted from dragon fruit (Hylocereus costaricensis) and blueberry fruit (Vaccinium corymbosum) are been used to analyze the dye characterization and absorption properties. In addition, the combination between TiO2 film and natural dyes are investigated for DSSC application.

M. A. Riyaz Ahmad; N. Nafarizal

2010-01-01

113

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

114

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

115

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.

2013-01-01

116

TiO2 Nanorod Arrays Sensitized with CdS Quantum Dots for Solar Cell Applications: Effects of Rod Geometry on Photoelectrochemical Performance  

NASA Astrophysics Data System (ADS)

CdS quantum dot (QD) sensitized TiO2 nanorod array (NRA) film electrodes with different rod geometries were fabricated via a solvothermal route followed by a sequentialchemical bath deposition (S-CBD) process. By controlling the solution growth conditions, the rod geometries, especially the tip structures, of the TiO2 NRAs were tuned. The results indicated that the vertically aligned hierarchical NRAs possessed conically shaped tip geometry, which was favorable for film electrodes due to the reduced reflectance, enhanced light harvesting, fast charge-carrier separation and transfer, suppression of carrier recombination, sufficient electrolyte penetration and subsequent efficient QD assembly. CdS QD sensitized TiO2 NRA film electrodes with tapered tips exhibited an enhanced photoelectrochemical (PEC) performance, a photocurrent intensity of 5.13 mA/cm2 at a potential of 0 V vs. saturated calomel electrode, an open-circuit potential of -0.68 V vs. saturated calomel electrode and an incident photon to current conversion efficiency (IPCE) of 22% in the visible-light region from 400 to 500 nm. The effects of rod geometry on the optical absorption, reflectance, hydrophilic properties and PEC performance of bare TiO2 and CdS QD sensitized TiO2 NRA film electrodes were investigated. The mechanism of charge-carrier generation and transfer in these CdS QD sensitized solar cells based on vertically aligned TiO2 nanorods is discussed.

Zhou, Jing; Song, Bin; Zhao, Gaoling; Dong, Weixia; Han, Gaorong

2012-05-01

117

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

118

Size-controlled synthesis of anisotropic TiO2 single nanocrystals using microwave irradiation and their application for dye-sensitized solar cells.  

PubMed

A microwave hydrothermal reaction of colloidal titanates is presented as a cost-effective synthesis to produce TiO(2) single nanocrystals. The photoelectrode consisting of anisotropic nanorods and V-shaped twins has a significant advantage for achieving an appreciable incident photon-to-current conversion efficiency of 85.6% for the dye-sensitized solar cell. PMID:23307102

Manseki, Kazuhiro; Kondo, Yosuke; Ban, Takayuki; Sugiura, Takashi; Yoshida, Tsukasa

2013-01-10

119

Au nanoparticle electrocatalysis in a photoelectrochemical solar cell using CdS quantum dot-sensitized TiO2 photoelectrodes.  

PubMed

A significant Au particle size-dependent electrocatalytic effect has been shown in a sandwich type photoelectrochemical solar cell consisting of CdS quantum dot (QD)-sensitized TiO(2) photoelectrodes, Au nanoparticle (NP)-loaded SnO(2) counter electrodes, and a polysulfide electrolyte solution intervening between the electrodes. PMID:19333474

Kiyonaga, Tomokazu; Akita, Tomoki; Tada, Hiroaki

2009-02-25

120

Rapid Charge Transport in Dye-Sensitized Solar Cells Made from Vertically Aligned Single-Crystal Rutile TiO2 Nanowires  

SciTech Connect

A rapid solvothermal approach was used to synthesize aligned 1D single-crystal rutile TiO2 nanowire (NW) arrays on transparent conducting substrates as electrodes for dye-sensitized solar cells. The NW arrays showed a more than 200 times faster charge transport (see picture) and a factor four lower defect state density than conventional rutile nanoparticle films.

Feng, X.; Zhu, K.; Frank, A. J.; Grimes, C. A.; Mallouk, T. E.

2012-03-12

121

Transparent Conducting Nb-Doped TiO2 Electrodes Activated by Laser Annealing for Inexpensive Flexible Organic Solar Cells  

NASA Astrophysics Data System (ADS)

A KrF excimer laser (? = 248 nm) has been adopted for annealing cost-effective Nb-doped TiO2 (NTO) films. Sputtered NTO layers were annealed on SiO2-coated flexible poly(ethylene terephthalate) (PET) substrates. This local laser annealing technique is very useful for the formation of anatase NTO electrodes used in flexible organic solar cells (OSCs). An amorphous NTO film with a high resistivity and a low transparency was transformed significantly into a conductive and transparent anatase NTO electrode by laser irradiation. The 210 nm anatase NTO film shows a sheet resistance of 50 ? and an average optical transmittance of 83.5% in the wavelength range from 450 to 600 nm after annealing at 0.25 J/cm2. The activation of Nb dopants and the formation of the anatase phase contribute to the high conductivity of the laser-annealed NTO electrode. Nb activation causes an increase in the optical band gap due to the Burstein--Moss effect. The electrical properties are in agreement with the material characteristics determined by X-ray diffraction (XRD) analysis and secondary ion mass spectrometry (SIMS). The irradiation energy for the NTO electrode also affects the performance of the organic solar cell. The laser annealing technique provides good properties of the anatase NTO film used as a transparent electrode for flexible organic solar cells (OSCs) without damage to the PET substrate or layer delamination from the substrate.

Lee, Jung-Hsiang; Lin, Chia-Chi; Lin, Yi-Chang

2012-01-01

122

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

123

Direct and seamless coupling of TiO2 nanotube photonic crystal to dye-sensitized solar cell: a single-step approach.  

PubMed

A TiO(2) nanotube layer with a periodic structure is used as a photonic crystal to greatly enhance light harvesting in TiO(2) nanotube-based dye-sensitized solar cells. Such a tube-on-tube structure fabricated by a single-step approach facilitates good physical contact, easy electrolyte infiltration, and efficient charge transport. An increase of over 50% in power conversion efficiency is obtained in comparison to reference cells without a photonic crystal layer (under similar total thickness and dye loading). PMID:22102221

Yip, Cho Tung; Huang, Haitao; Zhou, Limin; Xie, Keyu; Wang, Yu; Feng, Tianhua; Li, Jensen; Tam, Wing Yim

2011-11-07

124

One-Dimensional Hierarchical Nanostructures of TiO2 Nanosheets on SnO2 Nanotubes for High Efficiency Solid-State Dye-Sensitized Solar Cells.  

PubMed

Hierarchical nanostructures of TiO2 nanosheets on SnO2 nanotubes (SNT@TNS) are uniformly dispersed in an organized mesoporous (OM) TiO2 film with large pores, high porosity, and good interconnectivity. The solid-state dye sensitized solar cells (ssDSSCs) fabricated with 10 wt% SNT@TNS dispersed in a OM-TiO2 film show an energy conversion efficiency of 7.7% at 100 mW cm(-2) , which is one of the highest values for N719-based ssDSSCs and much larger than that of a randomly oriented TiO2 nanoparticles-based cell (4.0%). PMID:23857743

Ahn, Sung Hoon; Kim, Dong Jun; Chi, Won Seok; Kim, Jong Hak

2013-07-15

125

Dye stabilization and enhanced photoelectrode wettability in water-based dye-sensitized solar cells through post-assembly atomic layer deposition of TiO2.  

PubMed

Detachment (desorption) of molecular dyes from photoelectrodes is one of the major limitations for the long-term operation of dye-sensitized solar cells. Here we demonstrate a method to greatly inhibit this loss by growing a transparent metal oxide (TiO2) on the dye-coated photoelectrode via atomic layer deposition (ALD). TiO2-enshrouded sensitizers largely resist detachment, even in pH 10.7 ethanol, a standard solution for intentional removal of molecular dyes from photoelectrodes. Additionally, the ALD post-treatment renders the otherwise hydrophobic dye-coated surface hydrophilic, thereby enhancing photoelectrode pore-filling with aqueous solution. PMID:23876134

Son, Ho-Jin; Prasittichai, Chaiya; Mondloch, Joseph E; Luo, Langli; Wu, Jinsong; Kim, Dong Wook; Farha, Omar K; Hupp, Joseph T

2013-07-26

126

Spatial arrangement of carbon nanotubes in TiO2 photoelectrodes to enhance the efficiency of dye-sensitized solar cells.  

PubMed

Three electrode structures with different spatial arrangements of carbon nanotubes (CNTs) in the mesoporous TiO(2) layer were employed in dye-sensitized solar cells to study the effect of surface states at the interface formed by the incorporation of CNTs. It was found that the decay of open circuit voltage (V(oc)) was significantly minimized by avoiding the direct contact of nanotubes to the conducting substrate by introducing a thin buffer layer of TiO(2) while maintaining the superior electron collection efficiency from the incorporation of nanotubes. PMID:22336885

Nath, Narayan Chandra Deb; Sarker, Subrata; Ahammad, A J Saleh; Lee, Jae-Joon

2012-02-15

127

TiO2 micro/nano-composite structured electrodes for quasi-solid-state dye-sensitized solar cells  

NASA Astrophysics Data System (ADS)

Micro/nano-composite TiO2 porous films are prepared in a nutshell by the electro-hydrodynamic (EHD) method, and are applied to dye sensitized solar cells (DSSCs) successfully. Considering that micro/nano-composite structures based on the EHD technique are better for the filling of ionic liquid and quasi-solid-state electrolytes than liquid state electrolytes, a fill factor (ff) of 78.9% and a total photoelectric conversion efficiency (?) of 6.4% for ionic liquid electrolyte and an ff of 75.3% and an ? of 5.3% for quasi-solid-state electrolyte are obtained. Moreover, this kind of composite hierarchical structure may be of benefit for light collection because of strong light scattering. In order to obtain optimized devices, we probe into the influence of adding an amount of polymer on the photovoltaic performance, and find that by changing the concentration of the polymer during the EHD process the specific surface area of the films changes, which leads to different photovoltaic behaviour of solar cells.

Zhao, Yong; Zhai, Jin; Tan, Shuxin; Wang, Lifang; Jiang, Lei; Zhu, Daoben

2006-05-01

128

Solid-state dye-sensitized mesoporous TiO2 solar cells with high photon-to-electron conversion efficiencies  

Microsoft Academic Search

Solar cells based on dye-sensitized mesoporous films of TiO2 arelow-cost alternatives to conventional solid-state devices. Impressive solar-to-electrical energy conversion efficiencies have been achieved with such films when used in conjunction with liquid electrolytes. Practical advantages may be gained by the replacement of the liquid electrolyte with a solid charge-transport material. Inorganic p-type semiconductors, and organic materials have been tested in

U. Bach; D. Lupo; P. Comte; J. E. Moser; F. Weissörtel; J. Salbeck; H. Spreitzer; M. Grätzel

1998-01-01

129

Aqueous-Phase Linker-Assisted Attachment of Cysteinate(2(-))-Capped CdSe Quantum Dots to TiO2 for Quantum Dot-Sensitized Solar Cells.  

PubMed

We have synthesized water-dispersible cysteinate(2(-))-capped CdSe nanocrystals and attached them to TiO2 using one-step linker-assisted assembly. Room-temperature syntheses yielded CdSe magic-sized clusters (MSCs) exhibiting a narrow and intense first excitonic absorption band centered at 422 nm. Syntheses at 80 °C yielded regular CdSe quantum dots (RQDs) with broader and red-shifted first excitonic absorption bands. Cysteinate(2(-))-capped CdSe MSCs and RQDs adsorbed to bare nanocrystalline TiO2 films from aqueous dispersions. CdSe-functionalized TiO2 films were incorporated into working electrodes of quantum dot-sensitized solar cells (QDSSCs). Short-circuit photocurrent action spectra of QDSSCs corresponded closely to absorptance spectra of CdSe-functionalized TiO2 films. Power-conversion efficiencies were (0.43 ± 0.04)% for MSC-functionalized TiO2 and (0.83 ± 0.11)% for RQD-functionalized TiO2. Absorbed photon-to-current efficiencies under white-light illumination were approximately 0.3 for both MSC- and RQD-based QDSSCs, despite the significant differences in the electronic properties of MSCs and RQDs. Cysteinate(2(-)) is an attractive capping group and ligand, as it engenders water-dispersibility of CdSe nanocrystals with a range of photophysical properties, enables facile all-aqueous linker-assisted attachment of nanocrystals to TiO2, and promotes efficient interfacial charge transfer. PMID:23937323

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

2013-08-23

130

Ultrathin SnO2 scaffolds for TiO2-based heterojunction photoanodes in dye-sensitized solar cells: oriented charge transport and improved light scattering.  

PubMed

In this paper, band-structure matching strategy of a TiO2-based heterojunction within which electrons can be collected from TiO2 nanoparticles and transported rapidly in the bulk structure is reported. On the basis of the band-structure analysis of different TiO2-based heterostructures, focus was directed to the SnO2 nanosheet because of its appropriate band position and high electrical conductivity. Through a systematic investigation of the incorporation of ultrathin SnO2 nanosheet scaffolds for TiO2-based photoanodes in dye-sensitized solar cells (DSCs), we propose an anisotropy "constrained random walk" model to describe the controlled electron transit process. In this system, electrons are transferred orientedly overall, as well as randomly locally, leading to a significant reduction in the charge diffusion route compared to the conventional isotropic "random walk" model. In brief, the 2D ultrathin nanosheets provide rapid transit pathways and improved light-scattering centers, which can ensure a sufficient amount of dye loading and slow recombination. An overall light-to-electricity conversion efficiency as high as 8.25% is achieved by embedding the appropriate amount of SnO2 scaffold in a TiO2-based photoanode. PMID:23733334

Yang, Shuang; Hou, Yu; Xing, Jun; Zhang, Bo; Tian, Feng; Yang, Xiao Hua; Yang, Hua Gui

2013-06-03

131

Improved Nonaqueous Synthesis of TiO2 for Dye-Sensitized Solar Cells.  

PubMed

Nonaqueous synthesis routes have emerged as a powerful platform for directly obtaining diverse metal oxide nanoparticles with high crystallinity and tunable compositions. The benzyl alcohol (BA) route, for example, has been applied toward dozens of oxides including binary, ternary, and even more complex multimetal systems. Here we compare anatase nanoparticles made from the BA route with the traditional hydrothermal route. XPS measurements indicated that the BA route resulted in more reduced Ti states, corresponding to additional oxygen vacancies. These defects resulted in additional trap states, slower recombination, and slower charge transport. The performance of BA anatase was improved by incorporating niobium intended to suppress oxygen vacancies. The higher performance Nb-containing films were post-treated to yield a 7.96% power conversion efficiency (AM 1.5), similar to the state-of-the-art hydrolytic TiO2 in the same configuration. PMID:24015772

Stefik, Morgan; Heiligtag, Florian J; Niederberger, Markus; Grätzel, Michael

2013-09-16

132

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

PubMed

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

Lin, Jia; Chen, Jingfei; Chen, Xianfeng

2011-07-27

133

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.

2011-01-01

134

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

135

Dry-spray deposition of TiO2 for a flexible dye-sensitized solar cell (DSSC) using a nanoparticle deposition system (NPDS).  

PubMed

TiO2 powders were deposited on indium tin oxide (ITO) coated polyethylene terephthalate (PET) substrates for application to the photoelectrode of a dye-sensitized solar cell (DSSC). In the conventional DSSC manufacturing process, a semiconductor oxide such as TiO2 powder requires a sintering process at higher temperature than the glass transition temperature (T(g)) of polymers, and thus utilization of flexible polymer substrates in DSSC research has been constrained. To overcome this restriction related to sintering, we used a nanoparticle deposition system (NPDS) that could produce a thin coating layer through a dry-spray method under atmospheric pressure at room temperature. The powder was sprayed through a slit-type nozzle having a 0.4 x 10 mm2 rectangular outlet. In order to determine the deposited TiO2 thickness, five kinds of TiO2 layered specimens were prepared, where the specimens have single and double layer structures. Deposited powders on the ITO coated PET substrates were observed using FE-SEM and a scan profiler The thicker TiO2 photoelectrode with a DSSC having a double layer structure showed higher energy efficiency than the single layer case. The highest fabricated flexible DSSC displayed a short circuit current density J(sc) = 1.99 mA cm(-2), open circuit voltage V(oc) = 0.71 V, and energy efficiency eta = 0.94%. These results demonstrate the possibility of utilizing the dry-spray method to fabricate a TiO2 layer on flexible polymer substrates at room temperature under atmospheric pressure. PMID:22849129

Kim, Min-Saeng; Chun, Doo-Man; Choi, Jung-Oh; Lee, Jong-Cheon; Kim, Yang Hee; Kim, Kwang-Su; Lee, Caroline Sunyong; Ahn, Sung-Hoon

2012-04-01

136

New type of inorganic–organic hybrid (heteropolytungsticacid–polyepichlorohydrin) polymer electrolyte with TiO 2 nanofiller for solid state dye sensitized solar cells  

Microsoft Academic Search

A new type of inorganic–organic hybrid solid state polymer electrolyte consisting of heteropolytungsticacid impregnated polyepichlorohydrin with iodine\\/iodide and TiO2 nanofiller have been prepared for their potential application in dye sensitized solar cells. The prepared polymer electrolytes were well characterized by FT-IR, Scanning electron microscopy (SEM), X-ray diffraction (XRD), Electrochemical Impedance analysis (EIS) and Thermal analysis (TGA). The prepared polymer electrolyte

Radhakrishnan Sivakumar; Krishnasamy Akila; Sambandam Anandan

2010-01-01

137

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

NASA Astrophysics Data System (ADS)

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

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

2012-10-01

138

Dye-sensitized solar cells based on nitrogen-doped TiO2-B nanowire/TiO2 nanoparticle composite photoelectrode  

NASA Astrophysics Data System (ADS)

TiO2-B nanowire/TiO2 nanoparticle composite is an ideal nanomaterial for dye-sensitized solar cell photoelectrode because it combines the advantages of rapid electron transport in nanowires and high surface area of nanoparticles. Meanwhile, nitrogen doping is also an effective method for enhancing the photo-electrical conversion efficiency. In this work, nitrogen-doped TiO2-B nanowires are obtained using NH3 as a gaseous precursor under middle pressures. And the nitrogen-doped naowire/nanoparticle composite electrodes are fabricated. The conversion efficiency of nitrogen-doped nanowire/nanoparticle cells (7.21%) is higher than that of undoped nanowire/nanoparticle cells (6.10%) and nitrogen-doped nanoparticle cells (5.37%).

Qi, Lihong; Li, Chunyan; Chen, Yujin

2012-06-01

139

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

NASA Astrophysics Data System (ADS)

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

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

2013-10-01

140

Plasmon resonance enhanced optical absorption in inverted polymer/fullerene solar cells with metal nanoparticle-doped solution-processable TiO2 layer.  

PubMed

This paper investigates the effects of localized surface plasmon resonance (LSPR) in an inverted polymer/fullerene solar cell by incorporating Au and/or Ag nanoparticles (NPs) into the TiO2 buffer layer. Enhanced light harvesting via plasmonic resonance of metal NPs has been observed. It results in improved short-circuit current density (Jsc) while the corresponding open-circuit voltage (Voc) is maintained. A maximum power conversion efficiency of 7.52% is obtained in the case of introducing 30% Ag NPs into the TiO2, corresponding to a 20.7% enhancement compared with the reference device without the metal NPs. The device photovoltaic characteristics, photocurrent properties, steady-state and dynamic photoluminescences of active layer on metal NP-doped TiO2, and electric field profile in metal NP-doped TiO2 layers are systematically investigated to explore how the plasmonic effects of Au and/or Ag NPs influence the OSC performance. PMID:23510437

Xu, Mei-Feng; Zhu, Xiao-Zhao; Shi, Xiao-Bo; Liang, Jian; Jin, Yue; Wang, Zhao-Kui; Liao, Liang-Sheng

2013-04-02

141

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

PubMed Central

A compact TiO2 layer (~1.1 ?m) prepared by electrostatic spray deposition (ESD) and swift heavy ion beam (SHI) irradiation using oxygen ions onto a fluorinated tin oxide (FTO) conducting substrate showed enhancement of photovoltaic performance in dye-sensitized solar cells (DSSCs). The short circuit current density (Jsc = 12.2 mA cm-2) of DSSCs was found to increase significantly when an ESD technique was applied for fabrication of the TiO2 blocking layer, compared to a conventional spin-coated layer (Jsc = 8.9 mA cm-2). When SHI irradiation of oxygen ions of fluence 1 × 1013 ions/cm2 was carried out on the ESD TiO2, it was found that the energy conversion efficiency improved mainly due to the increase in open circuit voltage of DSSCs. This increased energy conversion efficiency seems to be associated with improved electronic energy transfer by increasing the densification of the blocking layer and improving the adhesion between the blocking layer and the FTO substrate. The adhesion results from instantaneous local melting of the TiO2 particles. An increase in the electron transport from the blocking layer may also retard the electron recombination process due to the oxidized species present in the electrolyte. These findings from novel treatments using ESD and SHI irradiation techniques may provide a new tool to improve the photovoltaic performance of DSSCs.

2011-01-01

142

A chemical precursor for depositing Sb2S3 onto mesoporous TiO2 layers in nonaqueous media and its application to solar cells.  

PubMed

Deposition of nanocrystalline Sb(2)S(3) onto a mesoporous TiO(2) photoanode is an important process in the fabrication of Sb(2)S(3)-sensitized solar cells. In order to generate oxide-free nanosized Sb(2)S(3), a single-source precursor for the chemical bath deposition of Sb(2)S(3) in nonaqueous media, Sb(III)(thioacetamide)(2)Cl(3), was synthesized and used to produce high-quality Sb(2)S(3) for solar cells. PMID:22918132

Maiti, Nilkamal; Im, Sang Hyuk; Lim, Choong-Sun; Seok, Sang Il

2012-08-23

143

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

144

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

NASA Astrophysics Data System (ADS)

We investigated CdSe-sensitized TiO2 solar cells by means of electrodeposition under galvanostatic control. The electrodeposition of CdSe within the mesoporous film of TiO2 gives rise to a uniform, thickness controlled, conformal layer of nanostructured CdSe particles intimately wrapping the anatase TiO2 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 TiO2-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 TiO2 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 (Voc = 485 mV, Jsc = 4.26 mA cm -2, ff=0.37).

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

2012-10-01

145

Using Micro-Arc Oxidation and Alkali Etching to Produce a Nanoporous TiO2 Layer on Titanium Foil for Flexible Dye-Sensitized Solar Cell Application  

NASA Astrophysics Data System (ADS)

To increase the specific surface area of a TiO2 layer synthesized by micro-arc oxidation (MAO), an alkali etching process was developed to form a nanoflaky structure in place of the existing microporous morphology of the MAO-TiO2 layer for dye-sensitized solar cell (DSSC) electrode application. An annealing treatment was also carried out to enhance the crystallinity of the nanofeatured TiO2 layer for a higher photovoltaic efficiency. Experimental results show that a 6-?m-thick crystalline porous TiO2 layer was fabricated on a Ti foil by MAO treatment, which consists of major amorphous and anatase phases with a minor rutile phase. As expected, the pores in the MAO-TiO2 layer exhibited micrometer-scale dimensions. The maximum photovoltaic efficiency realized in a device assembled with the MAO-TiO2 layer was only 0.061%. After alkali etching, a nanofeatured layer was developed over the MAO-TiO2 layer surface with numerous pores and nanoflakes of 50 nm size. These nanoflakes were uniformly distributed over the entire surface of the treated layer. The device assembled with the alkali-etched TiO2 layer exhibited an improved photovoltaic efficiency of 0.329%. This fivefold increase of the photovoltaic efficiency for the MAO-TiO2 layer indicates the effectiveness of enlarging the specific surface area by alkali etching. Furthermore, after postannealing, the crystallinity and fraction of the anatase phase in the overall TiO2 layer were enhanced. As a result, the photovoltaic efficiency ultimately reached 2.194%.

Wu, Shu-Yuan; Chen, Ying-Hung; Chen, Keh-Chang; He, Ju-Liang

2010-09-01

146

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

2012-09-12

147

Synthesis of mesoporous anatase TiO2 nanotubes by a hydrothermal treatment and their use in solid-state dye-sensitized solar cells.  

PubMed

Mesoporous anatase TiO2 nanotubes (NTs) with the diameter of about 7 12 nm and the length of several hundred nanometers were synthesized by a hydrothermal method on commercial TiO2 particles in NaOH followed by HCI washing. The samples were characterized by X-ray diffraction (XRD), transmitting electron microscopy (TEM), and Brunauer-Emmet-Teller (BET) measurements. The hydrothermal treatment temperature at 130 degrees C was shown to affect not only the extent of particle-to-sheet conversion, and thus the resulting structures of the NTs, but also the anatase-to-rutile transformation. The surface area of the NTs was 200 m2g(-1). This value was much higher in comparison to TiO2 nanoparticles of 50 m2g(-1). It was also found that the NT photoelectrodes had a pronounced impact on the performance of solar cells as compared to nanoparticle ones. This was probably due to lead to a significantly higher specific dye loading and, for certain hydrothermal treatments, resulting in a doubling of the solar cell efficiency (in our case from 2.84% to 4.03% of AM 1.5 conditions). PMID:21780512

Seo, Min-Kang; Park, Soo-Jin

2011-05-01

148

Synergistic effects of the aspect ratio of TiO2 nanowires and multi-walled carbon nanotube embedment for enhancing photovoltaic performance of dye-sensitized solar cells.  

PubMed

The existence of numerous interfacial boundaries among TiO2 nanoparticles (NPs) accumulated in the photoelectrode layer of dye-sensitized solar cells (DSSCs) hinders the effective transport of photogenerated electrons to an electrode. Therefore, as a replacement for TiO2 NPs, one-dimensional TiO2 nanowires (NWs) can be suggested to provide pathways for fast electron transport by significantly reducing the number of interfacial boundaries. In order to provide direct evidence for the better performance of such longer TiO2 NWs than shorter TiO2 NWs, we examine the effect of the controlled aspect ratio of the TiO2 NWs randomly accumulated in the photoelectrode layer on the photovoltaic performance of DSSCs. It is clearly found that longer TiO2 NWs significantly improve the electron transport by reducing the TiO2/dye/electrolyte interfacial contact resistance. Furthermore, the embedment of multi-walled carbon nanotubes (MWCNTs) as an effective charge transfer medium in longer TiO2 NWs is proposed in this study to promote more synergistic effects, which lead to significant improvements in the photovoltaic properties of DSSCs. PMID:23771100

Ahn, Ji Young; Kim, Ji Hoon; Moon, Kook Joo; Park, So Dam; Kim, Soo Hyung

2013-08-01

149

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

NASA Astrophysics Data System (ADS)

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

Yu, Jiefeng; Wang, Dan; Huang, Yining; Fan, Xing; Tang, Xin; Gao, Cong; Li, Jianlong; Zou, Dechun; Wu, Kai

2011-12-01

150

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.

2012-01-01

151

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

PubMed Central

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

2011-01-01

152

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

NASA Astrophysics Data System (ADS)

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

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

2012-06-01

153

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

154

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.

2013-01-01

155

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

NASA Astrophysics Data System (ADS)

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. PACS: 81.15.-z; 84.60.Jt; 73.40.Lq

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

2013-08-01

156

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

2013-08-16

157

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

PubMed

One approach to harvest a wide solar spectral solar energy is to stack two solar cells with different absorption characteristics in a tandem cell architecture. Herein, solution processed tandem solar cells, with highly transparent titanium oxide (TiO2) and graphene oxide (GO) as an efficient recombination layer, were designed, fabricated and characterized. We have adopted poly[(4,4'-bis(3-ethylhexyl)dithieno[3,2-b:''3'-d]silole)-2,6-diyl-alt-(2,5-(3-(2-ethylhexyl)thiophen-2-yl)thiazolo[5,4-d]thiazole]:indene-C60 bisadduct (PSEHTT:ICBA) and poly[(4,4'-bis(2-ethylhexyl)dithieno[3,2-b:2',3'-d]silole)-2,6-diyl-alt-(2,1,3-benzothiadiazole)-4,7-diyl]:[6,6]-phenyl-C70 butyric acid methyl ester (PSBTBT:PC70BM) as the active layers for the front and rear cells, respectively. The TiO2/GO serves as an electron and hole collecting and recombination layer. The tandem solar cells showed a high open circuit voltage (VOC) 1.62 V, a moderate short circuit current density (JSC) 8.23 mA cm(-2), fill factor (FF) 62.98%, leading to the power conversion efficiency of 8.40%. The obtained VOC value of tandem solar cells is ideal for the summation of VOCs attained from front and rear cells and it is evident that our tandem solar cells are well connected in series. Moreover, this tandem cell exhibits a 20% drop in conversion efficiency under continuous AM illumination for 2880 h. PMID:24071723

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

2013-09-26

158

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

159

Synergistic effect of ZnS outer layers and electrolyte methanol content on efficiency in TiO2/CdS/CdSe sensitized solar cells.  

PubMed

The effect of methanol content in water based polysulfide electrolytes in TiO(2)/CdS/CdSe quantum dot sensitized solar cells (QDSSCs) prepared by the SILAR method was studied. In addition, the effect of coating the mesoporous QD sensitized films with ZnS outer layers was investigated. Charge recombination reactions were measured using time resolved spectroscopic measurements. These studies reveal a synergistically beneficial effect from using ZnS layers and methanol in the polysulfide electrolyte on the control of charge transfer processes within these devices and ultimately on overall cell performance. PMID:22898785

Zewdu, Taye; Clifford, John N; Palomares, Emilio

2012-08-16

160

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

161

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

162

Large pore size and high porosity of TiO2 photoanode for excellent photovoltaic performance of CdS quantum dot sensitized solar cell.  

PubMed

While holding great potential as sunlight absorbers, quantum dots (QDs), which are generally much larger than dye molecule in size, which makes it more difficult to deposit them on the surface of TiO2. As a result, relatively low QD loading is now one of the most challenging issues for improving the photovoltaic performance of QD-sensitized solar cells (QDSSC). In this study, TiO2 photoanodes with different pore sizes and porosities were constructed by systematically varying the solid content of the TiO2 paste. It was confirmed that reducing the solid content resulted in both larger pore sizes and higher porosities. CdS quantum dots were then deposited on these different electrodes by the successive ionic layer adsorption and reaction (SILAR) method, with either 4 or 7 repetitive cycles. By correlating the photovoltaic performances of QDSSCs with different solid contents of TiO2 paste and number of SILAR cycles of CdS QD deposition, it was found that the combination of 7 SILAR cycles with 10% electrode solid content yielded the highest overall energy conversion efficiency. In particular this cell exhibited an outstanding open-circuit photovoltage up to 640 mV using a polysulfide electrolyte, which currently ranks the highest among reported literature. This outcome is due to the fact that a 10%-solid-content provided the largest pore sizes and the highest porosity for the QDs deposition, while the 7 SILAR cycles guaranteed the sufficient CdS QD loading which is favorable for light harvesting. PMID:23646579

Shen, Heping; Lin, Hong; Zhao, Lin; Liu, Yizhu; Oron, Dan

2013-02-01

163

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

2013-03-19

164

Analysis of adsorption properties of N719 dye molecules on nanoporous TiO 2 surface for dye-sensitized solar cell  

NASA Astrophysics Data System (ADS)

Ordered nanoporous TiO 2 materials (MK-TiO 2, MS-TiO 2, and MU-TiO 2) were synthesized for the dye-sensitized solar cell (DSSC) by using different silica templates such as KIT-6, SBA-15, and MSU-H. To prepare a photoelectrode in DSSC, cis-bis(isothiocyanato)bis(2,2'-bipyridyl-4,4'-dicarboxylato)-ruthenium(II)bis-tetrabutylammonium dye (N719) was adsorbed onto the synthesized nanoporous TiO 2 materials. The samples were characterized by XRD, TEM, FE-SEM, AFM, and N 2 adsorption analyses. The photovoltaic performance of DSSC was evaluated from the overall conversion efficiency, fill factor, open-circuit voltage, and short-circuit current from the I- V curves measured. It was found that the photoelectric performance is highly dependent on the adsorption properties of N719 dye molecules on the nanoporous TiO 2 replicas (MK-TiO 2, MS-TiO 2, and MU-TiO 2) synthesized from different silica templates.

Hwang, Kyung-Jun; Shim, Wang-Geun; Jung, Sung-Hoon; Yoo, Seung-Joon; Lee, Jae-Wook

2010-06-01

165

MnTe semiconductor-sensitized boron-doped TiO2 and ZnO photoelectrodes for solar cell applications.  

PubMed

We report a new tailoring MnTe semiconductor-sensitized solar cells (MnTe SSCs) using successive ionic layer adsorption and reaction (SILAR) technique. X-ray diffraction and SAED patterns reveal the orthorhombic MnTe and cubic MnTe2 phases were grown on boron-doped TiO2 and ZnO nanoparticles. The diameter of MnTe NPs ranged from 15 to 30nm on both B-doped metal oxide structures. The energy gaps of metal oxide become narrower after boron doping, which have an advantage for enhancing the light absorption from UV to visible region. Also, the energy gap of MnTe NPs on B-doped metal oxide was determined ~1.27-1.30eV. The best power conversion efficiency (?) of 0.033% and 0.030% yielded from B-doped TiO2/MnTe(7) and B-doped ZnO/MnTe(9), respectively. The reduction in power conversion efficiency by 103% and 91% was due to the absence of boron doping into TiO2 and ZnO nanostructures, respectively. PMID:23786831

Tubtimtae, Auttasit; Arthayakul, Khanittha; Teekwang, Bussayanee; Hongsith, Kritsada; Choopun, Supab

2013-05-31

166

Dye-sensitized solar cells based on thick highly ordered TiO2 nanotubes produced by controlled anodic oxidation in non-aqueous electrolytic media  

NASA Astrophysics Data System (ADS)

Dye-sensitized solar cells (DSSCs) were prepared using TiO2 nanotubes, grown by controlled Ti anodic oxidation in non-aqueous media. Smooth, vertically oriented TiO2 nanotube arrays, presenting a high degree of self-organization and a length of 20 µm, have been grown using ethylene glycol electrolyte containing HF. As-grown nanotubes exhibit an amorphous structure, which transforms to the anatase TiO2 crystalline phase upon post-annealing in air at 450 °C. Atomic force microscopy (AFM) revealed the porous morphology together with high roughness and fractality of the surface. The annealed tubes were sensitized by the standard N719 ruthenium dye and the adsorption was characterized using resonance micro-Raman spectroscopy and adsorption-desorption measurements. The sensitized tubes were further used as active photoelectrodes after incorporation in sandwich-type DSSCs using both liquid and solidified electrolytes. The efficiencies obtained under air mass (AM) 1.5 conditions, using a back-side illumination geometry, were very promising: 0.85% using a composite polymer redox electrolyte, while the efficiency was further increased up to 1.65% using a liquid electrolyte.

Stergiopoulos, T.; Ghicov, A.; Likodimos, V.; Tsoukleris, D. S.; Kunze, J.; Schmuki, P.; Falaras, P.

2008-06-01

167

Enhanced Photovoltaic Performance of Nanowire Dye-Sensitized Solar Cells Based on Coaxial TiO2@TiO Heterostructures with a Cobalt(II/III) Redox Electrolyte.  

PubMed

The growth of a TiO shell at the surface of TiO2 nanowires (NWs) allowed us to improve the power conversion efficiency of NW-based dye-sensitized solar cells (DSCs) by a factor 2.5. TiO2@TiO core-shell NWs were obtained by a two-step process: First, rutile-phase TiO2 NWs were hydrothermally grown. Second, a hongquiite-phase TiO shell was electrochemically deposited at the surface of the TiO2 NWs. Bare TiO2 and heterojunction TiO2@TiO NW-based DSCs were obtained using a cobalt(II/III) redox electrolyte and LEG4 as the dye. With this electrolyte/dye combination, DSCs with outstanding Voc values above 900 mV were systematically obtained. While TiO2@TiO NW-based DSCs had slightly lower Voc values than bare TiO2 NW-based DSCs, they provided 3-fold higher photocurrents, overall reaching 2.5-fold higher power conversion efficiencies. The higher photocurrents were associated with the larger surface roughness and an enhanced charge-carrier separation/transfer at the NW/dye interface. PMID:24025444

Fan, Jiandong; Fàbrega, Cristian; Zamani, Reza R; Hao, Yan; Parra, Andres; Andreu, Teresa; Arbiol, Jordi; Boschloo, Gerrit; Hagfeldt, Anders; Morante, Joan Ramon; Cabot, Andreu

2013-09-12

168

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

NASA Astrophysics Data System (ADS)

TiO2 nanotube arrays were prepared by electrochemical anodization using as-fabricated FTO glass which coated with Ti membrance.Ag2S quantum dots (QDs) and N3 dye (Ag2S -N3-TNAs) were prepared by the processes of sequential chemical bath deposition (S-CBD) approach.We assembled the co-sensitized solar cells model in form of sandwich.We researched the transferring of electrons amongst energy band of Ag2S, N3 and TNAs.

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

2013-10-01

169

Fabrication and performance of nanoporous TiO 2 \\/SnO 2 electrodes with a half hollow sphere structure for dye sensitized solar cells  

Microsoft Academic Search

The incorporation of nano-crystalline semiconductors with novel kinds of ordered microstructure is a very important area of\\u000a research in the field of dye sensitized solar cells. A sol–gel method involving hydrolysis of titanium isopropoxide was used\\u000a to form TiO2 nanoparticles on the surface of SiO2 spheres. In this process, 1, 5, or 10 wt% of SnCl2.2H2O was added to the sol–gel

Yu-Rim Bak; Gyeong-Ok Kim; Moon-Jin Hwang; Kwon-Koo Cho; Ki-Won Kim; Kwang-Sun Ryu

2011-01-01

170

Photovoltaic performance of dye sensitized solar cell based on rutile TiO 2 scaffold electrode prepared by a 2 step bi-layer process using molten salt matrices  

Microsoft Academic Search

Dye sensitized solar cells were made on TiO2 scaffold anodes of rutile particles. These TiO2 scaffold anodes were grown from rutile seeds by using a molten salt synthesis technique. Different thickness coatings of mixed amorphous titanium hydroxide and NaCl–KCl eutectic salt mixture on the rutile seeds were heat treated at different temperatures. The rutile whiskers of different aspect ratios were

B. Roy; P. A. Fuierer; S. Aich

2011-01-01

171

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

172

CdS quantum dots sensitized solar cells based on free-standing and through-hole TiO2 nanotube arrays.  

PubMed

Front-side illuminated solar cells with CdS quantum dots (QDs) incorporated with free-standing through-hole TiO2 nanotube arrays (TNAs) were developed. The solar cells, based on TNAs with different lengths that were sensitized by successive ionic layer adsorption and reaction method (SILAR) with various cycles, have been tested. The morphology and crystalline phase of the TiO2 nanotubes were studied by field emission scanning electron microscopy (FESEM) and X-ray diffraction (XRD). The crystallized free-standing through-hole TNAs were easily transferred to the fluorine-doped tin oxide glass to form a photoanode by slightly modifying the anodization procedure. The SILAR technique enables us to control the loading amount and particle size of CdS QDs by altering deposition cycles. The cells with TNAs ca. 20 ?m long (obtained by anodization for 4 h) and 5 SILAR cycles show a photovoltaic conversion efficiency as high as 1.187% under simulated sunlight (AM 1.5, 100 mW cm(-2)). PMID:23887557

Wang, Xuelai; Zheng, Jun; Sui, Xiaotao; Xie, Hao; Liu, Baoshun; Zhao, Xiujian

2013-10-01

173

Determination of the light-induced degradation rate of the solar cell sensitizer N719 on TiO2 nanocrystalline particles.  

PubMed

The oxidative degradation rate, kdeg, of the solar cell dye (Bu4N+)2[Ru(dcbpyH)2(NCS)2]2-, referred to as N719 or [RuL2(NCS)2], was obtained by applying a simple model system. Colloidal solutions of N719-dyed TiO2 particles in acetonitrile were irradiated with 532-nm monochromatic light, and the sum of the quantum yields for the oxidative degradation products [RuL2(CN)2], [RuL2(NCS)(CN)], and [RuL2(NCS)(ACN)], Phideg, was obtained at eight different light intensities in the range of 0.1-16.30 mW/cm2 by LC-UV-MS. The Phideg values decreased from 3.3 x 10-3 to 2.0 x 10-4 in the applied intensity range. By using the relation kdeg = Phidegkback and back electron-transfer reaction rates, kback, obtained with photoinduced absorption spectroscopy, it was possible to calculate an average value for the oxidative degradation rate of N719 dye attached to TiO2 particles, kdeg = 4.0 x 10-2 s-1. The stability of N719 dye during solar cell operation was discussed based on this number, and on values of the electron-transfer rate between [Ru(III)L2(NCS)2] and iodide ion that are available in the literature. PMID:16853919

Nour-Mohhamadi, Farahnaz; Nguyen, Sau Doan; Boschloo, Gerrit; Hagfeldt, Anders; Lund, Torben

2005-12-01

174

Efficiency enhancement of CuInS2 quantum dot sensitized TiO2 photo-anodes for solar cell applications  

NASA Astrophysics Data System (ADS)

Two-step process had been employed to enhance the photovoltaic performance of CuInS2 quantum dot sensitized solar cells. 3.5 nm MPA-capped CuInS2 quantum dots were firstly adsorbed on the TiO2 nanoparticle films by assembly linking technique. And then large amount of CuInS2 quantum dots were deposited on the photo-anodes by SILAR technique. The UV–Vis absorption edge of the photo-anodes from two-step process had greatly expanded from 400 nm to 800 nm. These solar cells exhibited the IPCE peak value of 36% and photovoltaic efficiency of 1.85%, which was much higher than that from individual assembly linking and SILAR technique.

Peng, Zhuoyin; Liu, Yueli; Shu, Wei; Chen, Keqiang; Chen, Wen

2013-10-01

175

Enhanced electron lifetime on nitrogen-doped TiO2 films for dye-sensitized solar cells.  

PubMed

Nitrogen-doped TiO2 crystallites were prepared via the hydrolysis of TiCl4 using an ammonia medium in an aqueous solution for DSSC photoelectrodes. The optimized photoelectrode for the DSSC was prepared with 9.4 nm sized N-doped TiO2 crystal (BET; 200 m2/g), which provides a relatively high short circuit current and energy conversion efficiency in the DSSC. The photovoltaic performance of the N-doped TiO2 electrode was confirmed using incident photon-to-current efficient spectra, impedance analyses, and Bode-phase plots which proved that the N-doped TiO2 electrode has a significantly enhanced electron lifetime compared with that of the P25 electrode. PMID:22849112

Yun, Tae Kwan; Cheon, Jong Hun; Bae, Jae Young; Ahn, Kwang-Soon; Kim, Jae Hong

2012-04-01

176

Multilayer TiO2 nanorod cloth/nanorod array electrode for dye-sensitized solar cells and self-powered UV detectors  

NASA Astrophysics Data System (ADS)

A multilayer TiO2 nanorod-assembled cloth/nanorod array based electrode was fabricated by transferring different layers of TiO2 nanorod-assembled cloth (TNRC) onto nanorod array grown on the conducting FTO substrate (titania nanorod, TNR). Combining the superior electron transport characteristics of TNR and outstanding optical properties of TNRC, the nanostructured electrode composed of two layers of TNRC meets the optimized design for high quality dye-sensitized solar cells (DSCs) and self-powered UV detectors. The highest efficiency of 4.02% for DSC under AM 1.5 was achieved with a high short circuit current density of 9.81 mA cm-2, which was proved to be owing to the enhanced dye anchoring, light scattering and reduced charge recombination. For the photoelectrochemical (PEC) UV detector, the highest quantum efficiency of over 46% was obtained and a high photocurrent response of 0.271 mA cm-2 was observed, together with the excellent self-powered, fast response and ``visible blind'' characteristics. A perfect linear response to the changed low-power signal indicates great potential for practical applications.A multilayer TiO2 nanorod-assembled cloth/nanorod array based electrode was fabricated by transferring different layers of TiO2 nanorod-assembled cloth (TNRC) onto nanorod array grown on the conducting FTO substrate (titania nanorod, TNR). Combining the superior electron transport characteristics of TNR and outstanding optical properties of TNRC, the nanostructured electrode composed of two layers of TNRC meets the optimized design for high quality dye-sensitized solar cells (DSCs) and self-powered UV detectors. The highest efficiency of 4.02% for DSC under AM 1.5 was achieved with a high short circuit current density of 9.81 mA cm-2, which was proved to be owing to the enhanced dye anchoring, light scattering and reduced charge recombination. For the photoelectrochemical (PEC) UV detector, the highest quantum efficiency of over 46% was obtained and a high photocurrent response of 0.271 mA cm-2 was observed, together with the excellent self-powered, fast response and ``visible blind'' characteristics. A perfect linear response to the changed low-power signal indicates great potential for practical applications. Electronic supplementary information (ESI) available: OCVD data, Nyquist plots in dark with different bias for DSC. Time-resolved photocurrent plots, J-V curves in dark and radiation power spectrum for UV detector testing. See DOI: 10.1039/c2nr30440f

Wang, Zhuoran; Ran, Sihan; Liu, Bin; Chen, Di; Shen, Guozhen

2012-05-01

177

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

2012-10-03

178

Multilayer TiO2 nanorod cloth/nanorod array electrode for dye-sensitized solar cells and self-powered UV detectors.  

PubMed

A multilayer TiO(2) nanorod-assembled cloth/nanorod array based electrode was fabricated by transferring different layers of TiO(2) nanorod-assembled cloth (TNRC) onto nanorod array grown on the conducting FTO substrate (titania nanorod, TNR). Combining the superior electron transport characteristics of TNR and outstanding optical properties of TNRC, the nanostructured electrode composed of two layers of TNRC meets the optimized design for high quality dye-sensitized solar cells (DSCs) and self-powered UV detectors. The highest efficiency of 4.02% for DSC under AM 1.5 was achieved with a high short circuit current density of 9.81 mA cm(-2), which was proved to be owing to the enhanced dye anchoring, light scattering and reduced charge recombination. For the photoelectrochemical (PEC) UV detector, the highest quantum efficiency of over 46% was obtained and a high photocurrent response of 0.271 mA cm(-2) was observed, together with the excellent self-powered, fast response and "visible blind" characteristics. A perfect linear response to the changed low-power signal indicates great potential for practical applications. PMID:22549639

Wang, Zhuoran; Ran, Sihan; Liu, Bin; Chen, Di; Shen, Guozhen

2012-05-01

179

High-performance plastic dye-sensitized solar cells based on low-cost commercial P25 TiO2 and organic dye.  

PubMed

High-performance plastic dye-sensitized solar cells (DSCs) based on low-cost commercial Degussa P25 TiO(2) and organic indoline dye D149 have been fabricated using electrophoretic deposition (EPD) with compression post-treatment at room temperature. The pressed EPD electrode outperformed the sintered EPD electrode and as-prepared EPD electrode in short-circuit current density and power conversion efficiency. About 150% and 180% enhancement in power conversion efficiency have been achieved in DSC devices with sintering and compression post-treatment as compared to the as-prepared electrode, respectively. Several characterizations including intensity modulated photocurrent spectroscopy, incident photon-to-electron conversion efficiency and electrochemical impedance spectra have been employed to reveal the nature of improvement with post-treatment. Experimental results indicate that the sintering and compression post-treatment are beneficial to improve the electron transport and thus lead to the enhancement of photocurrent and power conversion efficiency. In addition, the compression post-treatment is more efficient than sintering post-treatment in improving interparticle connection in the as-prepared EPD electrode. Under optimized conditions, the conversion efficiency of plastic devices with D149-sensitized P25 TiO(2) photoanode has reached 5.76% under illumination of AM 1.5G (100 mW cm(-2)). This study demonstrates that the EPD combined with compression post-treatment provides a way to fabricate highly efficient plastic photovoltaic devices. PMID:22324725

Yin, Xiong; Xue, Zhaosheng; Wang, Long; Cheng, Yueming; Liu, Bin

2012-02-22

180

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

2012-12-31

181

Scattering spherical voids in nanocrystalline TiO2- enhancement of efficiency in dye-sensitized solar cells.  

PubMed

Spherical voids as light scattering centers in nanocrystalline TiO2 films were realized with polystyrene particles of diameter 400 nm, thus enhancing the photovoltaic performance by 25% on large areas, as well as providing an indication that these films can be used with electrolytes of higher viscosity. PMID:15834489

Hore, Sarmimala; Nitz, Peter; Vetter, Carmen; Prahl, Christof; Niggemann, Michael; Kern, Rainer

2005-02-23

182

TiO2 composing with pristine, metallic or semiconducting single-walled carbon nanotubes: which gives the best performance for a dye-sensitized solar cell.  

PubMed

Different types of single-walled carbon nanotubes (SWCNTs), pristine (p-), metallic (m-) and semiconducting (s-) are incorporated into TiO(2) photoanodes to improve the dye-sensitized solar-cell (DSSC) performance and their effects on the device performance are further investigated. Although all three types of SWCNTs are found to have comparable structural morphologies and a reduced charge transport resistivity for the photoanodes, only the semiconducting one was able to suppress charge-recombination events, resulting in even greater improvement of DSSC performances. This is very likely to be ascribed to the higher energy barrier of s-SWCNTs compared to both m- and p-SWCNTs to block the back flowing of dye-injected electrons for I(3)(-) reduction in the charge recombination process. PMID:22674658

Guai, Guan Hong; Li, Yao; Ng, Chee Mang; Li, Chang Ming; Chan-Park, Mary B

2012-06-06

183

Dye bonding to TiO2: in situ attenuated total reflection infrared spectroscopy study, simulations, and correlation with dye-sensitized solar cell characteristics.  

PubMed

Processing dye-sensitized solar cells gains more and more importance as interest in industrial applications grows daily. For large-scale processing and optimizing manufacturing in terms of environmental acceptability as well as time and material saving, a detailed knowledge of certain process steps is crucial. In this paper we concentrate on the sensitizing step of production, i.e., the anchoring of the dye molecules onto the TiO(2) semiconductor. A vacuum-tight attentuated total reflection infrared (ATR-IR) flow-through cell was developed, thus allowing measurements using a vacuum spectrometer to monitor infiltration of dye molecules into the porous TiO(2) film in situ at high sensitivity. In particular, the influence of the anchor and backbone of perylene dye molecules as well as the influence of solvents on the adsorption process was investigated. The experiments clearly show that an anhydride group reacts much slower than an acid group. A significantly lower amount of anhydride dye can be adsorbed on the films. Ex situ transmission experiments furthermore indicate that the availability of OH groups on the TiO(2) surface may limit dye adsorption. Also the backbone and base frame of the dye can influence the adsorption time drastically. Electrical cell characteristics correlate with the amount of adsorbed dye molecules determined by in situ ATR-IR measurements. The latter is also sensitive toward the diffusion of the dye through the porous layer. To gain a deeper understanding of the interplay between diffusion and adsorption, simulations were performed that allowed us to extract diffusion and adsorption constants. Again it was demonstrated that the anchoring group has a strong effect on the adsorption rate. The influence of the solvent was also studied, and it was found that both adsorption and desorption are affected by the solvent. Protic polar solvents are able to remove bound dye molecules, which is a possible pathway of cell degradation. Most importantly, the analysis shows the potential of this approach for the evaluation of molecules or additives concerning their characteristics important for cell processing. PMID:22775480

Völker, Barbara; Wölzl, Florian; Bürgi, Thomas; Lingenfelser, Dominic

2012-07-25

184

A novel metal-free panchromatic TiO2 sensitizer based on a phenylenevinylene-conjugated unit and an indoline derivative for highly efficient dye-sensitized solar cells.  

PubMed

A novel donor-?-spacer-acceptor type organic dye (AK01) bearing a phenylenevinylene-conjugated system and a derivative of indoline donor was synthesized for dye-sensitized solar cells. AK01 showed panchromatic TiO(2) sensitization with high overall conversion efficiency of 6.2% under AM 1.5 illumination (100 mW cm(-2)). PMID:22016888

Akhtaruzzaman, Md; Islam, Ashraful; Yang, Fan; Asao, Naoki; Kwon, Eunsang; Singh, Surya Prakash; Han, Liyuan; Yamamoto, Yoshinori

2011-10-21

185

Removing structural disorder from oriented TiO2 nanotube arrays: reducing the dimensionality of transport and recombination in dye-sensitized solar cells.  

PubMed

We report on the influence of morphological disorder, arising from bundling of nanotubes (NTs) and microcracks in films of oriented TiO2 NT arrays, on charge transport and recombination in dye-sensitized solar cells (DSSCs). Capillary stress created during evaporation of liquids from the mesopores of dense TiO2 NT arrays was of sufficient magnitude to induce bundling and microcrack formation. The average lateral deflection of the NTs in the bundles increased with the surface tension of the liquids and with the film thicknesses. The supercritical CO2 drying technique was used to produce bundle-free and crack-free NT films. Charge transport and recombination properties of sensitized films were studied by frequency-resolved modulated photocurrent/photovoltage spectroscopies. Transport became significantly faster with decreased clustering of the NTs, indicating that bundling creates additional pathways via intertube contacts. Removing such contacts alters the transport mechanism from a combination of one and three dimensions to the expected one dimension and shortens the electron-transport pathway. Reducing intertube contacts also resulted in a lower density of surface recombination centers by minimizing distortion-induced surface defects in bundled NTs. A causal connection between transport and recombination is observed. The dye coverage was greater in the more aligned NT arrays, suggesting that reducing intertube contacts increases the internal surface area of the films accessible to dye molecules. The solar conversion efficiency and photocurrent density were highest for DSSCs incorporating films with more aligned NT arrays owing to an enhanced light-harvesting efficiency. Removing structural disorder from other materials and devices consisting of nominally one-dimensional architectures (e.g., nanowire arrays) should produce similar effects. PMID:17983250

Zhu, Kai; Vinzant, Todd B; Neale, Nathan R; Frank, Arthur J

2007-11-06

186

Enhanced light harvesting in mesoporous TiO2/P3HT hybrid solar cells using a porphyrin dye.  

PubMed

We report panchromatic light harvesting in hybrid TiO(2)/P3HT photovoltaic devices using a porphyrin dye that complements the light absorption of P3HT. The high short circuit photocurrent (12.1 mA cm(-2)) obtained is found to be due, in part, to Förster resonance energy transfer from the P3HT to the dye. PMID:21706100

Moon, Soo-Jin; Baranoff, Etienne; Zakeeruddin, Shaik M; Yeh, Chen-Yu; Diau, Eric Wei-Guang; Grätzel, Michael; Sivula, Kevin

2011-06-27

187

Effects of calcination treatment on the morphology, crystallinity, and photoelectric properties of all-solid-state dye-sensitized solar cells assembled by TiO2 nanorod arrays.  

PubMed

TiO2 has been extensively investigated due to its unique photoelectric properties. In this study, oriented single-crystal rutile TiO2 nanorod arrays were synthesized and then calcined at different temperatures in the atmosphere. The morphology and crystalline characterization indicated that the length of TiO2 nanorods increased rapidly and the nanorods became aggregated and fragile after calcination, yet the sintering treatment seemed to have almost no effect on the crystallinity. To obtain the all-solid-state, dye-sensitized solar cells (DSSCs), a newly reported solid inorganic semiconductor, CsSnI2.95F0.05, was employed as the electrolyte, and the Pt deposited on the conductive side of the fluorine-doped tin oxide (FTO) glass substrate was used as the counter-electrode. The effects of the calcination treatment on the photoelectric properties of the solar cells, including external quantum efficiency (EQE), open circuit voltage (VOC), short-circuit current (JSC), and photoelectric conversion efficiency (?), were investigated under the illumination of a solar simulator. As a result, all of the EQE, VOC, JSC, and ? values of the cells first increased and then declined with the increase of calcination temperatures, and the highest ? of 2.81% was obtained by the cell assembled with its TiO2 electrode sintered at 450 °C for 3 h, a value almost 2.5 times that of the non-sintered sample (1.1%). PMID:24071636

Sun, Xianmiao; Sun, Qiong; Li, Yang; Sui, Lina; Dong, Lifeng

2013-10-01

188

Organic dye-sensitized sponge-like TiO2 photoanode for dye-sensitized solar cells.  

PubMed

Light harvesting inside a solar cell is crucial for overall performance. Increasing the optical path of a photon through the delicate design of photoanode morphology can increase the light absorbance. The marine sponge-like photoanode is facilely constructed and assembled into a solar cell, using an organic D-A-?-A-type dye with wide-spectrum response as the sensitizer. The light scattering derived from the large porous cavities in the photoanode enhances the improved light absorbance of the dye molecules, especially in the long-wavelength region, and therefore improves the cell efficiency. Synergistically engineering the photoanode morphology and adopting matchable dye maximized the light energy conversion efficiency in this study, and a maximal conversion efficiency of 5.02% was achieved. PMID:24000365

Liu, Jian; Yang, Qiang; Li, Mingzhu; Zhu, Weihong; Tian, He; Song, Yanlin

2013-09-02

189

PEO electrolytes containing dioctyl phthalate (DOP) for dye-sensitized nanocrystalline TiO 2 solar cells  

Microsoft Academic Search

In this paper, we aim to prepare polymer electrolytes consisting of NaI and I2 dissolved in poly(ethylene oxide) (PEO) and dioctyl phthalate (DOP) as an additive and apply the electrolytes to dye-sensitized\\u000a solar cells (DSSC). Upon the incorporation of salt, the phthalic-stretching C=O bands of DOP in Fourier transform infrared\\u000a spectra shifted to a lower wave number (?f?=?93 cm?1), confirming the

So Yeon Bang; Kyung Ju Lee; Joo Hwan Koh; Moon-Sung Kang; Yong Soo Kang; Jong Hak Kim

2008-01-01

190

Zinc-doping in TiO2 films to enhance electron transport in dye-sensitized solar cells under low-intensity illumination.  

PubMed

A nanocrystalline TiO(2) film with highly dispersed Zn-doping shows its capability for efficient electron transport in dye-sensitized solar cells (DSSCs). The Zn-doping is conducted via Zn(2+) introduction into a layered titanate followed by hydrothermal treatment and calcination. The Zn-doped films exhibit an elevated electron Fermi level, which may enhance band bending to lower the density of empty trap states. Because of this Zn-doping, the consequent DSSCs can alleviate the decay of light-to-electric energy conversion efficiency due to light intensity reduction. Intensity-modulated spectroscopic analysis reveals that enhanced transport of photogenerated electrons as a result of the trap density minimization is responsible for the high cell performance under low-intensity illumination. A Zn-doping content of ca. 0.4 at% Zn/Ti can enhance the light conversion efficiency by 23% at a solar light intensity as low as 11 mW cm(-2). This technique can significantly extend the indoor application of DSSCs. PMID:19830333

Wang, Kai-Ping; Teng, Hsisheng

2009-08-18

191

Improvement of light-harvesting efficiency in dye-sensitized solar cells using silica beads embedded in a TiO2 nanoporous structure  

NASA Astrophysics Data System (ADS)

The effect of various materials of the spherical scattering centre in a TiO2 nanoporous structure in dye-sensitized solar cells (DSSCs) was investigated by both theoretical simulation and experiment. Three materials, titania, electrolyte and silica, were investigated using the Mie Theory, in which the concepts of volume total cross section and solar spectrum were accommodated for better accuracy. Of those materials, silica was chosen in this study due to its perfectly transparent nature, easy size controllability and perfectly spherical shape, which make silica most suitable for understanding the scattering effect with a simple optical approach. The validity was proved by experiment with various sizes of silica beads (0.3, 0.6, 0.9, 1.2, 1.5 µm) embedded in DSSCs; experiments revealed the same trend as did the simulation. The overall efficiency of the DSSCs was increased by 20.4% using 300 nm diameter silica beads. The efficiency versus bead size had a peak with beads of 300 nm diameter and decreased as the bead size increased. This study showed that silica could be a good candidate for scattering particles in DSSCs. Furthermore, this study could be considered a valuable reference for further investigations of scattering phenomena by small spherical particles or arbitrary shape of particles in DSSCs.

Rho, Yoonsoo; Wanit, Manorotkul; Yeo, Junyeob; Hong, Sukjoon; Han, Seungyong; Choi, Jun-Ho; Hong, Won-Hwa; Lee, Dongjin; Ko, Seung Hwan

2013-01-01

192

A facile route to fabricate an anodic TiO2 nanotube-nanoparticle hybrid structure for high efficiency dye-sensitized solar cells  

NASA Astrophysics Data System (ADS)

The relatively low internal surface area of anodized TiO2 nanotube arrays (TNAs) limits dye adsorption and light capturing in TNA-based dye-sensitized solar cells (DSSCs). Here, water treatment of as-anodized TNAs at room temperature was used to tailor the geometry of TNA walls in a controllable way, leading to a hybrid tube wall structure with the outer shell in a tubular morphology and the inner surface consisting of small particles. To enable front-side illumination in DSSCs, the TNAs with porous inner walls were transferred to transparent conductive oxide substrates by a self-detaching and transfer technique. The roughened water-treated TNAs show significantly enhanced internal surface area, leading to improved dye-loading and light-harvesting capabilities. Optimized performance was achieved after water treatment for 2 days, with a power conversion efficiency of 6.06%, increased by ~33% compared to conventional TNAs. Furthermore, the hybrid TNA nanostructure provides excellent electron transfer and recombination characteristics, thus promising for high efficiency DSSCs.The relatively low internal surface area of anodized TiO2 nanotube arrays (TNAs) limits dye adsorption and light capturing in TNA-based dye-sensitized solar cells (DSSCs). Here, water treatment of as-anodized TNAs at room temperature was used to tailor the geometry of TNA walls in a controllable way, leading to a hybrid tube wall structure with the outer shell in a tubular morphology and the inner surface consisting of small particles. To enable front-side illumination in DSSCs, the TNAs with porous inner walls were transferred to transparent conductive oxide substrates by a self-detaching and transfer technique. The roughened water-treated TNAs show significantly enhanced internal surface area, leading to improved dye-loading and light-harvesting capabilities. Optimized performance was achieved after water treatment for 2 days, with a power conversion efficiency of 6.06%, increased by ~33% compared to conventional TNAs. Furthermore, the hybrid TNA nanostructure provides excellent electron transfer and recombination characteristics, thus promising for high efficiency DSSCs. Electronic supplementary information (ESI) available. See DOI: 10.1039/c2nr31268a

Lin, Jia; Liu, Xiaolin; Guo, Min; Lu, Wei; Zhang, Guoge; Zhou, Limin; Chen, Xianfeng; Huang, Haitao

2012-07-01

193

Nanosilver-Decorated TiO2 Nanofibers Coated with a SiO2 Layer for Enhanced Light Scattering and Localized Surface Plasmons in Dye-Sensitized Solar Cells.  

PubMed

Enhanced harvesting of visible light is vital to the development of highly efficient dye-sensitized solar cells (DSSCs). Nanosilver-decorated TiO2 nanofibers (Ag@TiO2 NFs) were synthesized by depositing chemically reduced Ag ions onto the surface of electrospun TiO2 nanofibers (TiO2 NFs). The prepared Ag@TiO2 NFs were coated with SiO2 (SiO2 @Ag@TiO2 NFs) by using PVP as coupling agent for protecting corrosion of Ag nanoparticle by I(-) /${{\\rm I}{{- \\hfill \\atop 3\\hfill}}}$ solution. The fabricated SiO2 @Ag@TiO2 NFs demonstrated a synergistic effect of light scattering and surface plasmons, leading to an enhanced light absorption. Moreover, an anode consisting of SiO2 @Ag@TiO2 NFs incorporating TiO2 nanoparticles (NPs) increased light harvesting without substantially sacrificing dye attachment. The power conversion efficiency increased from 6.8 to 8.7?% for a thick film (10??m), that is, 28?%. These results suggest that SiO2 @Ag@TiO2 NFs are promising materials for enhanced light absorption in dye-sensitized solar cells. PMID:23934778

Hwang, Sun Hye; Roh, Jongmin; Jang, Jyongsik

2013-08-09

194

Dual-functional hetero-structured TiO2 nanotrees composed of rutile trunks and anatase branches for improved performance of quantum dot-sensitized solar cells.  

PubMed

We developed a two-step hydrothermal method to prepare hetero-structured TiO2 nanotree arrays on FTO substrates. This process included the deposition of rutile nanorod arrays with a length of about 2 ?m as trunks at first and then the growth of the anatase nanosheets with the thickness of less than 10 nm standing on the rutile trunks through a dissolution-growth process. After being coated with CdS and CdSe quantum dots, these nanotrees were used as photoanodes in the quantum dot-sensitized solar cells (QDSSCs). It was found that the branches could enlarge the surface area of the anode, increase the amount of the deposited quantum dots, and thus improve the light absorption of the whole device. Moreover, the electron transport dynamics indicated that the phase junctions between the rutile trunks and anatase nanosheets could accelerate the electron transport in the QDSSCs. As a result, we got a conversion efficiency of ?2.4% with the thickness of less than 2 ?m, which was 50% higher than that in the nanorod array-based QDSSCs. PMID:24043014

Zhu, Feng; Dong, Hui; Wang, Yi; Wu, Dapeng; Li, Jianming; Pan, Jinlong; Li, Qi; Ai, Xicheng; Zhang, Jianping; Xu, Dongsheng

2013-10-01

195

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 cm(2)) or a parallel module containing three single cells (total active area 5.4 cm(2)). 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

2013-10-04

196

Highly uniform, bifunctional core/double-shell-structured ?-NaYF4:Er3+, Yb3+ @ SiO2@TiO2 hexagonal sub-microprisms for high-performance dye sensitized solar cells.  

PubMed

Highly uniform core/double-shell-structured ?-NaYF4:Er(3+),Yb(3+)@SiO2@TiO2 hexagonal sub-microprisms are prepared and employed in dye-sensitized solar cells (DSCs) internally. This work paves a facile way to enable the most-efficient upconversion material (?-NaYF4:Er(3+),Yb(3+)) to be used as scattering and upconversion centers in the photoelectrode of a DSC. PMID:23420696

Liang, Liangliang; Liu, Yumin; Bu, Chenghao; Guo, Kaimo; Sun, Weiwei; Huang, Niu; Peng, Tao; Sebo, Bobby; Pan, Mengmei; Liu, Wei; Guo, Shishang; Zhao, Xing-Zhong

2013-02-18

197

Effect of salt composition on photovoltaic performance of the dye-sensitized solar cells prepared from nano anatase TiO 2 powder using NaCl–Na 2 HPO 4 ·2H 2 O salt matrices  

Microsoft Academic Search

Photovoltaic performances of dye-sensitized solar cells based on mesoporous TiO2 coating of nanocrystalline anatase prepared by solid salt synthesis were investigated in this study. Three different salt\\u000a compositions pure NaCl, NaCl and DSP 50–50 wt% mixture, and pure DSP have been used as the reaction mediums. The best photovoltaic\\u000a performances were obtained for the device made using the powder from DSP

B. Roy; L. Li; S. Aich

2011-01-01

198

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

199

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

200

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

201

Free standing TiO2 nanotube array electrodes with an ultra-thin Al2O3 barrier layer and TiCl4 surface modification for highly efficient dye sensitized solar cells  

NASA Astrophysics Data System (ADS)

Dye sensitized solar cells were fabricated with free standing TiO2 nanotube (TNT) array films, which were prepared by template assisted atomic layer deposition (ALD) with precise wall thickness control. Efforts to improve the photovoltaic performance were made by using Al2O3 barrier layer coating in conjunction with TiCl4 surface modification. An Al2O3 thin layer was deposited on the TNT electrode by ALD to serve as the charge recombination barrier, but it suffers from the drawback of decreasing the photoelectron injection from dye into TiO2 when the barrier layer became too thick. With the TiCl4 treatment in combination with optimal thickness coating, this problem could be avoided. The co-surface treated electrode presents superior surface property with low recombination rate and good electron transport property. A high conversion efficiency of 8.62% is obtained, which is about 1.8 times that of the device without surface modifications.Dye sensitized solar cells were fabricated with free standing TiO2 nanotube (TNT) array films, which were prepared by template assisted atomic layer deposition (ALD) with precise wall thickness control. Efforts to improve the photovoltaic performance were made by using Al2O3 barrier layer coating in conjunction with TiCl4 surface modification. An Al2O3 thin layer was deposited on the TNT electrode by ALD to serve as the charge recombination barrier, but it suffers from the drawback of decreasing the photoelectron injection from dye into TiO2 when the barrier layer became too thick. With the TiCl4 treatment in combination with optimal thickness coating, this problem could be avoided. The co-surface treated electrode presents superior surface property with low recombination rate and good electron transport property. A high conversion efficiency of 8.62% is obtained, which is about 1.8 times that of the device without surface modifications. Electronic supplementary information (ESI) available: UV-Vis spectra of desorbed N719 dyes from TiO2 electrodes with and without Al2O3 barrier. See DOI: 10.1039/c3nr03198e

Gao, Xianfeng; Guan, Dongsheng; Huo, Jingwan; Chen, Junhong; Yuan, Chris

2013-10-01

202

Tunable, Highly Ordered TiO2 Nanotube Arrays on Indium Tin Oxide Coated PET for Flexible Bio-sensitized Solar Cells.  

National Technical Information Service (NTIS)

Highly ordered, free-standing titanium dioxide (TiO2) nanotube (TNT) arrays have been of intense interest in the alternative energies field in recent years due to their barrier-free electron conduction pathway versus TiO2 nanoparticles in dye sensitized s...

J. J. Martin

2011-01-01

203

Interfacial energy levels and related properties of atomic-layer-deposited Al2O3 films on nanoporous TiO2 electrodes of dye-sensitized solar cells  

NASA Astrophysics Data System (ADS)

Low-temperature (~150 °C), atomic-layer-deposited Al2O3 films on nanoporous TiO2 electrodes of dye-sensitized solar cells (DSSCs) were investigated using electron spectroscopy. The power conversion efficiency (PCE) of the DSSCs was increased from 5.7% to 6.5%, an improvement of 14%, with one monolayer of Al2O3 with a thickness of ~0.2 nm. The formation of Ti-O-Al(OH)2 and interfacial dipole layers exhibited a strong influence on the work function of the Al2O3 over-layers, while the thicker Al2O3 over-layers caused the values of valence band maximum and band gap to approach the values associated with pure Al2O3. A work function difference (??A-T) of 0.4 eV and a recombination barrier height (?RB) of 0.1 eV were associated with the highest PCE achieved by the first monolayer of the Al2O3 layer. Thicker Al2O3 over-layers, however, caused significant reduction of PCE with negative ??T-A and increased interfacial energy barrier height (*?IB) between the N719 dyes and TiO2 electrodes. It was concluded that the PCE of the DSSCs may correlate with ??A-T, ?RB, and *?IB resulting from various thicknesses of the Al2O3 over-layers and that interfacial reactions, such as the formation of Ti-O-Al(OH)2 and dipole layers, play an important role in determining the interfacial energy levels required to achieve optimal performance of dye-sensitized TiO2 solar cells.

Tien, Ta-Chang; Pan, Fu-Ming; Wang, Lih-Ping; Lee, Chia-Hua; Tung, Yung-Liang; Tsai, Song-Yeu; Lin, Ching; Tsai, Feng-Yu; Chen, Su-Jen

2009-07-01

204

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

205

Synthesis of hierarchically organized nanostructured TiO2 by pulsed laser deposition and its application to dye-sensitized solar cells  

Microsoft Academic Search

Hierarchically organized TiO2 nanostructures were synthesized on fluorine-doped SnO2(FTO)\\/glass substrate at room temperature under various oxygen pressures using pulsed laser deposition (PLD). The microstructures of the obtained TiO2 nanostructures were changed sensitively as oxygen pressure. A fully dense structure could be achieved below oxygen pressure of 50 mTorr. However, ultrafine nanoparticles (5~15 nm) were produced over 50 mTorr and they

Jun Hong Noh; Jong Hun Park; Hyun Soo Han; Sangwook Lee; Dong Hoe Kim; Hyun Suk Jung; Kung Sun Hong

2010-01-01

206

Highly-ordered TiO2 nanotube arrays up to 220 µm in length: use in water photoelectrolysis and dye-sensitized solar cells  

Microsoft Academic Search

The fabrication of highly-ordered TiO2 nanotube arrays up to 134 µm in length by anodization of Ti foil has recently been reported (Paulose et al 2006 J. Phys. Chem. B 110 16179). This work reports an extension of the fabrication technique to achieve TiO2 nanotube arrays up to 220 µm in length, with a length-to-outer diameter aspect ratio of ap1400,

Karthik Shankar; Gopal K. Mor; Haripriya E. Prakasam; Sorachon Yoriya; Maggie Paulose; Oomman K. Varghese; Craig A. Grimes

2007-01-01

207

Fabrication of TiO 2 nanotubes by using electrodeposited ZnO nanorod template and their application to hybrid solar cells  

Microsoft Academic Search

Vertically aligned TiO2 nanotubes have been fabricated on the indium-doped tin oxide (ITO) by a simple and versatile technique using the electrochemically deposited ZnO nanorods, oriented along the c-axis, as a template in the spin-on based sol–gel reaction of a Ti precursor. The diameter, length, and shape of TiO2 nanotubes were controlled by changing the initial ZnO nanorod template and

Seok-In Na; Seok-Soon Kim; Woong-Ki Hong; Jeong-Woo Park; Jang Jo; Yoon-Chae Nah; Takhee Lee; Dong-Yu Kim

2008-01-01

208

TiO 2 nanotubes for hydrogen generation by photocatalytic water splitting in a two-compartment photoelectrochemical cell  

Microsoft Academic Search

Highly ordered TiO2 nanotube arrays for hydrogen production have been synthesized by electrochemical anodization of titanium sheets. Under solar light irradiation, hydrogen generation by photocatalytic water splitting was carried out in the two-compartment photoelectrochemical cell without any external applied voltage. The hydrogen gas and oxygen generated on Pt side and on TiO2 nanotubes side respectively were efficiently separated. The effect

Yan Sun; Guixin Wang; Kangping Yan

2011-01-01

209

Effect of hydrogen plasma treatment on nano-structured TiO2 films for the enhanced performance of dye-sensitized solar cell  

NASA Astrophysics Data System (ADS)

We report an efficient method to improve the efficiency and stability of DSSC with nano-structured TiO2. A low temperature RF plasma-enhanced chemical vapor deposition (PECVD) system was utilized for hydrogen plasma treatment on nano-structured TiO2 film. We confirmed that the efficiency of DSSCs was significantly dependent on the plasma power. This increased the hydrophilic property, the excess electrons and dye adsorption on its surface. The relative change in surface chemistry and hydrophilic characteristics with plasma treatment was investigated using various analysis methods. In our study, we showed that DSSC with plasma-treated TiO2 had a power conversion efficiency of 6.94%, which is 21% higher than that without plasma treatment. It was found that the plasma treatment caused both increased dye adsorption and significant longer electron lifetime.

Kim, Hyung Jin; Kim, Jumi; Hong, Byungyou

2013-06-01

210

Free standing TiO2 nanotube array electrodes with an ultra-thin Al2O3 barrier layer and TiCl4 surface modification for highly efficient dye sensitized solar cells.  

PubMed

Dye sensitized solar cells were fabricated with free standing TiO2 nanotube (TNT) array films, which were prepared by template assisted atomic layer deposition (ALD) with precise wall thickness control. Efforts to improve the photovoltaic performance were made by using Al2O3 barrier layer coating in conjunction with TiCl4 surface modification. An Al2O3 thin layer was deposited on the TNT electrode by ALD to serve as the charge recombination barrier, but it suffers from the drawback of decreasing the photoelectron injection from dye into TiO2 when the barrier layer became too thick. With the TiCl4 treatment in combination with optimal thickness coating, this problem could be avoided. The co-surface treated electrode presents superior surface property with low recombination rate and good electron transport property. A high conversion efficiency of 8.62% is obtained, which is about 1.8 times that of the device without surface modifications. PMID:24056866

Gao, Xianfeng; Guan, Dongsheng; Huo, Jingwan; Chen, Junhong; Yuan, Chris

2013-09-13

211

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

212

Suitability of amorphous TiO2 nanoparticles as a photoelectrode in dye sensitized solar cells: A DFT-TDDFT study  

NASA Astrophysics Data System (ADS)

Ab-initio calculations of nano-sized (˜1 nm) amorphous-TiO2 cluster and dye molecules (N3 and N719) have been carried out. Optimized structures of amorphous cluster and dye molecules have been obtained via molecular dynamics (MD) and density functional theory (DFT) calculations, respectively. The lowest excited state energies of the TiO2 cluster and the dye molecules have been obtained using time-dependent DFT. The calculations show that HOMO-LUMO gap and singlet-singlet excited state energies for amorphous cluster are very similar to that of a crystalline TiO2 cluster. Our calculations also show that the energy levels of the molecular dyes are well aligned with those of the amorphous cluster.

Eithiraj, R. D.; Geethalakshmi, K. R.

2013-10-01

213

Synthesis, characterization, photocatalytic activity and dye-sensitized solar cell performance of nanorods\\/nanoparticles TiO 2 with mesoporous structure  

Microsoft Academic Search

Nanorods\\/nanoparticles TiO2 with mesoporous structure were synthesized by hydrothermal method at 150°C for 20h. The samples characterized by XRD, SEM, TEM, SAED, HRTEM, and BET surface area. The nanorods had diameter about 10–20nm and the lengths of 100–200nm, the nanoparticles had diameter about 5–10nm. The prepared material had average pore diameter about 7–12nm. The BET surface area and pore volume

Sorapong Pavasupree; Supachai Ngamsinlapasathian; Masafumi Nakajima; Yoshikazu Suzuki; Susumu Yoshikawa

2006-01-01

214

TiO 2-fixed-bed reactor for water decontamination using solar light  

Microsoft Academic Search

A photocatalytic reactor using immobilized TiO2 (Degussa P25) on a glass plate was studied on a bench scale using solar light as the source of radiation. The influence of parameters such as the slope of the plate, solar light intensity, flow rate and molar flow rate, as well as the geometry of the reactor, was studied using dichloroacetic acid (DCA)

Raquel F. P. Nogueira; Wilson F. Jardim

1996-01-01

215

TiO2 nanorod arrays functionalized with In2S3 shell layer by a low-cost route for solar energy conversion  

Microsoft Academic Search

We report the fabrication and characterization of a TiO2-In2S3 core-shell nanorod array structure for application of semiconductor-sensitized solar cells. Hydrothermally synthesized TiO2 nanorod arrays on FTO glass substrates are functionalized with a uniform In2S3 shell layer by using the successive ion layer adsorption and reaction (SILAR) method. This low-cost technique promotes a uniform deposition of In2S3 nanoshells on the surface

Xiaoyan Gan; Xiaomin Li; Xiangdong Gao; Jijun Qiu; Fuwei Zhuge

2011-01-01

216

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

National Technical Information Service (NTIS)

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 invest...

A. J. Frank N. R. Neale N. Kopidakis J. van de Lagemaat M. Graetzel

2005-01-01

217

Constructing WO3/TiO2 composite structure towards sufficient use of solar energy.  

PubMed

A WO(3)/TiO(2) composite is constructed with the ability to degrade organic molecules under visible irradiation, which is newly explored by UV pre-irradiation. The long lasting visible-light photoactivity and the consecutive photocatalytic process will benefit the efficient use of solar energy. PMID:21359291

Su, Dan; Wang, Jingyu; Tang, Yupan; Liu, Cheng; Liu, Lifei; Han, Xijiang

2011-02-25

218

TiO2 and TiO2\\/WO3 porous film electrodes for application in solar energy conversion  

Microsoft Academic Search

TiO2 and TiO2\\/WO3 porous films were deposited onto transparent conducting glass electrodes, resulting in uniform films consisted of agglomerated particles with average diameters ranging from 50 to 200 nm; Ti, O and W atoms were homogeneously distributed at the surface of hybrid film. Comparable electrochemical properties were observed in the dark, with small capacitive currents and similar potentials for O2

Haroldo G. Oliveira; Erika D. Silva; Claudia Longo

2009-01-01

219

An ultrathin TiO2 blocking layer on Cd stannate as highly efficient front contact for dye-sensitized solar cells.  

PubMed

An engineered multilayer structure of platinum-cadmium stannate-titanium oxide (Pt-CTO-TO), with different TO layer thickness (in the range 1-5 nm), has been grown at 400 °C on glass substrates by RF magnetron sputtering, following a 2-step procedure without breaking vacuum. To produce an alternative and reliable front contact for dye sensitized solar cells (DSCs), morphology and composition of a TO blocking layer have been studied, paying particular attention to the oxide-oxide (CTO-TO) interface characteristics. The influence of the metallic mesh on the transparent conductive oxide sheet resistance has also been considered. A sputtered CTO layer shows a high average transmittance, over 90%. The Pt mesh yields a drastic reduction in the series resistance, almost one order, without affecting the optical properties. The ultrathin blocking layer of Ti oxide prevents charge recombination, improving the overall performance of the solar cells: +86% in efficiency, +50% in short circuit current, with respect to bare CTO. PMID:24000007

Braga, Antonio; Baratto, Camilla; Colombi, Paolo; Bontempi, Elza; Salvinelli, Gabriele; Drera, Giovanni; Sangaletti, Luigi

2013-09-02

220

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

2013-05-16

221

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.

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

2012-01-01

222

Homogeneous Photosensitization of Complex TiO2 Nanostructures for Efficient Solar Energy Conversion  

NASA Astrophysics Data System (ADS)

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.

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

2012-06-01

223

Solar photocatalytic disinfection with immobilised TiO(2) at pilot-plant scale.  

PubMed

The photocatalytic disinfection efficiency has been investigated for two immobilized TiO(2) catalytic systems (wall reactor and fixed-bed reactor) in a solar pilot plant. Their performances have been compared with the use of a slurry reactor and the solar disinfection without catalyst. The use of photocatalytic TiO(2) wall reactors does no show clear benefits over the solar disinfection process in the absence of catalyst. The reason is that the efficiency of the solar disinfection is so high that the presence of titania in the reactor wall reduces the global efficiency due to the competition for the absorption of photons. As expected, the maximum efficiency was shown by the slurry TiO(2) reactor, due to the optimum contact between bacteria and catalyst. However, it is noticeable that the use of the fixed-bed reactor leads to inactivation rate quite close to that of the slurry, requiring comparable accumulated solar energy of about 6 kJ L(-1) to achieve a 6-log decrease in the concentration of viable bacteria and allowing a total disinfection of the water (below the detection limit of 1 CFU mL(-1)). Not only the high titania surface area of this configuration is responsible for the bacteria inactivation but the important contribution of the mechanical stress has to be considered. The main advantage of the fixed-bed TiO(2) catalyst is the outstanding stability, without deactivation effects after ten reaction cycles, being readily applicable for continuous water treatment systems. PMID:20107278

Sordo, Carlos; Van Grieken, Rafael; Marugán, Javier; Fernández-Ibáñez, Pilar

2010-01-01

224

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.

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

2012-01-01

225

Solar photocatalytic mineralization of isoproturon over TiO 2\\/HY composite systems  

Microsoft Academic Search

The present investigation covers immobilization of titanium dioxide over HY support for the treatment of isoproturon pesticide. Catalysts are characterized by XRD, SEM–EDAX, TEM, BET surface area and UV–vis DRS. A detailed photocatalytic degradation study under solar light in aqueous suspensions with parameters like loading of TiO2 over HY, amount of the catalyst, concentration of substrate, pH effect, durability of

Mangalampalli V. Phanikrishna Sharma; Kannekanti Lalitha; Valluri Durgakumari; Machiraju Subrahmanyam

2008-01-01

226

Continuous flow photochemical reactor for solar decontamination of water using immobilized TiO 2  

Microsoft Academic Search

A photochemical reactor is designed for solar decontamination of organic pollutants in water, where the nanocrystalline photocatalyst TiO2 is immobilized on glass. The reactor modules could be connected in series and\\/or parallel to achieve desired flow rates under different conditions of illumination and degree of contamination. Methyl violet and phenol was found to completely degrade under solor irradiation and flow

G. R. R. A Kumara; F. M Sultanbawa; V. P. S Perera; I. R. M Kottegoda; K Tennakone

1999-01-01

227

TiO2 nanorod arrays functionalized with In2S3 shell layer by a low-cost route for solar energy conversion.  

PubMed

We report the fabrication and characterization of a TiO(2)-In(2)S(3) core-shell nanorod array structure for application of semiconductor-sensitized solar cells. Hydrothermally synthesized TiO(2) nanorod arrays on FTO glass substrates are functionalized with a uniform In(2)S(3) shell layer by using the successive ion layer adsorption and reaction (SILAR) method. This low-cost technique promotes a uniform deposition of In(2)S(3) nanoshells on the surface of TiO(2) nanorods, thus forming an intact interface between the In(2)S(3) shell and TiO(2) core. Results show that the thickness of In(2)S(3) shell layers as well as the visible light absorption threshold can be effectively controlled by varying the coating cycles during the SILAR process. The best reproducible performance of the sandwich solar cell using the TiO(2)-In(2)S(3) core-shell nanorod arrays as photoelectrodes was obtained after 30 SILAR cycles, exhibiting a short-circuit current (I(sc)) of 2.40 mA cm(-2), an open-circuit voltage (V(oc)) of 0.56 V, a fill factor (ff) of 0.40 and a conversion efficiency (?) of 0.54%, respectively. These results demonstrate a feasible and controllable route towards In(2)S(3) coating on a highly structured substrate and a proof of concept that such TiO(2)-In(2)S(3) core-shell architectures are novel and promising photoelectrodes in nanostructured solar cells. PMID:21697580

Gan, Xiaoyan; Li, Xiaomin; Gao, Xiangdong; Qiu, Jijun; Zhuge, Fuwei

2011-06-23

228

Solar light induced degradation of trichloroethylene (TCE) using TiO2: effects of solar light intensity and seasonal variations.  

PubMed

The feasibility of the trichloroethylene (TCE) degradation using solar light was investigated. With both solar light and TiO2 present, TCE was more effectively degraded than either with solar light or TiO2 alone. The rate of photocatalytic degradation under a clear sky was about five and 18 times higher than that of photocatalytic degradation under cloudy and thick cloudy skies, respectively. The optimization of the degradation rates was strongly dependent on the solar light intensity. All experimental data were fit to a first-order rate equation. Summer showed faster degradation rate than winter. From the mass balance, this study showed that over 80% of chloride in clear and partly cloudy skies was mineralized from TCE degradation. PMID:12940492

Park, Jaehong; Choi, Euiso; Cho, Il-Hyoung; Kim, Young-Gyu

2003-09-01

229

Solar photocatalysis for detoxification and disinfection of water: Different types of suspended and fixed TiO 2 catalysts study  

Microsoft Academic Search

Photocatalysis by titanium dioxide (TiO2), operational in the UV-A domain with a potential use of solar radiation, could be an alternative to conventional water detoxification and disinfection technologies. However, employing the photocatalyst as a suspension or slurry makes the scaling-up of the process difficult, as the TiO2 has to be removed from the decontaminated water to be reused several times.

D. Gumy; A. G. Rincon; R. Hajdu; C. Pulgarin

2006-01-01

230

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

231

A dye sensitized TiO 2 photoelectrochemical cell constructed with polymer solid electrolyte  

Microsoft Academic Search

We report the first all solid-state dye sensitized TiO2 photoelectrochemical cell with polymer solid electrolyte. Oligoethylene glycol methacrylate was used as a polymer solid electrolyte. Ethylene glycol and lithium iodide were added to it to enhance the performance. In order to make a tight contact with the TiO2 porous film, the polymer solid electrolyte was prepared by radical polymerization after

Masamitsu Matsumoto; Hiromitsu Miyazaki; Kikuo Matsuhiro; Yoshimasa Kumashiro; Yoichi Takaoka

1996-01-01

232

Detecting HER2 on cancer cells by TiO2 spheres Mie scattering.  

PubMed

This work is the first to describe a bioimaging method that uses highly uniformly sized TiO(2) submicrometer and micrometer spheres based on Mie scattering. Transmembrane proteins (HER2) located on the surface of cancer cells were detected by bonded antibody-linked TiO(2) spheres using optic microscopy and UV-vis spectroscopy. A particular HER2 bond on cancer cells, which has a weaker binding affinity than the biotin/avidin interaction, can be identified between TiO(2) spheres that are linked to anti-HER2 antibodies and those that are linked to nonspecific mouse IgG antibodies by observing the cells under an optical microscope or by measuring absorbance from a UV-vis spectrum. The TiO(2) spheres used in this work was prepared by reacting TTIP with carboxylic acid, as described elsewhere and the uniformity of the TiO(2) sphere was further improved by adjusting the amount of water used. The water content was inversely related to particle size and the size distribution: as more water was used, smaller spheres with a narrower size distribution were obtained. The most uniform sphere obtained had a diameter of about 1 microm with a size variation of 3%. PMID:19653662

Tsai, Min-Chiao; Tsai, Tsung-Lin; Shieh, Dar-Bin; Chiu, Hsin-Tien; Lee, Chi-Young

2009-09-15

233

Water annealing and other low temperature treatments of anodic TiO 2 nanotubes: A comparison of properties and efficiencies in dye sensitized solar cells and for water splitting  

Microsoft Academic Search

The present work compares different annealing treatments for TiO 2 nanotubes in terms of their photoelectrochemical performance. First, self-organized TiO 2 nanotubes were grown in a most typical electrolyte of 0.5 wt% NH 4F + 2 wt% H 2O in ethylene glycol to length of ?15 ?m. These \\

N. Liu; S. P. Albu; K. Lee; S. So; P. Schmuki

2012-01-01

234

Pathways of solar light-induced photocatalytic degradation of azo dyes in aqueous TiO 2 suspensions  

Microsoft Academic Search

The photocatalytic degradation of aqueous solutions of Acid Orange 7 in TiO2 suspensions has been investigated with the use of a solar light simulating source. The photoreaction was followed by monitoring the degradation of the dye and the formation of intermediates and final products, as functions of time of irradiation, both in solution and on the photocatalyst surface. It has

Maria Stylidi; Dimitris I. Kondarides; Xenophon E. Verykios

2003-01-01

235

Optimization of solar photocatalytic degradation conditions of Reactive Yellow 14 azo dye in aqueous TiO 2  

Microsoft Academic Search

The photocatalytic decolourisation and degradation of an azo dye Reactive Yellow 14 (RY14) in aqueous solution with TiO2-P25 (Degussa) as photocatalyst in slurry form have been investigated using solar light. The study on the effect of various photocatalysts on the decolourisation and degradation reveals the following order of reactivity: ZnO>TiO2-P25>TiO2 (anatase). CdS, Fe2O3 and SnO2 have negligible activity on RY14

M. Muruganandham; N. Shobana; M. Swaminathan

2006-01-01

236

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.

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

2012-01-01

237

TiO2 nanotube structures for enhanced cell and biological functionality  

Microsoft Academic Search

Nanostructures have pronounced effects on biological processes such as growth of cells and their functionality. Advances in biomaterial surface structure and design have resulted in improved tissue engineering. Nanotechnology can be utilized for optimization of titanium implants with a formation of vertically aligned TiO2 nanotube arrays on the implant surface. The anodic oxidation of the titanium implant surface to form

Karla S. Brammer; Seunghan Oh; Christine J. Frandsen; Sungho Jin

2010-01-01

238

TiO2 film/Cu2O microgrid heterojunction with photocatalytic activity under solar light irradiation.  

PubMed

Coupling a narrow-band-gap semiconductor with TiO(2) is an effective method to produce photocatalysts that work under UV-vis light irradiation. Usually photocatalytic coupled-semiconductors exist mainly as powders, and photocatalytic activity is only favored when a small loading amount of narrow-band-gap semiconductor is used. Here we propose a heavy-loading photocatalyst configuration in which 51% of the surface of the TiO(2) film is covered by a Cu(2)O microgrid. The coupled system shows higher photocatalytic activity under solar light irradiation than TiO(2) and Cu(2)O films. This improved performance is due to the efficient charge transfer between the two phases and the similar opportunity each has to be exposed to irradiation and adsorbates. PMID:20355842

Zhang, Junying; Zhu, Hailing; Zheng, Shukai; Pan, Feng; Wang, Tianmin

2009-10-01

239

Solar light induced and TiO2 assisted degradation of textile dye reactive blue 4.  

PubMed

Aqueous solutions of reactive blue 4 textile dye are totally mineralised when irradiated with TiO2 photocatalyst. A solution containing 4 x 10(-4) M dye was completely degraded in 24 h irradiation time. The intensity of the solar light was measured using Lux meter. The results showed that the dye molecules were completely degraded to CO2, SO4(2-), NO3-, NH4+ and H2O under solar irradiation. The addition of hydrogen peroxide and potassium persulphate influenced the photodegradation efficiency. The rapidity of photodegradation of dye intermediates were observed in the presence of hydrogen peroxide than in its absence. The auxiliary chemicals such as sodium carbonate and sodium chloride substantially affected the photodegradation efficiency. High performance liquid chromatography and chemical oxygen demand were used to study the mineralisation and degradation of the dye respectively. It is concluded that solar light induced degradation of textile dye in wastewater is a viable technique for wastewater treatment. PMID:11951983

Neppolian, B; Choi, H C; Sakthivel, S; Arabindoo, B; Murugesan, V

2002-03-01

240

Solar photocatalytic degradation of a reactive azo dye in TiO 2suspension  

Microsoft Academic Search

The photocatalytic decolourisation and degradation of an azo dye reactive orange 4 (RO4) in aqueous solution with TiO2-P25 (Degussa) as photocatalyst in slurry form have been investigated using solarlight. There is a significant difference in adsorption of dye on TiO2 surface with the change in solution pH. The effect of various photocatalysts such as TiO2-P25, TiO2 (anatase), ZnO, CdS, Fe2O3,

M Muruganandham; M Swaminathan

2004-01-01

241

Solar Driven Photooxidation Chemistry on TiO2 Surfaces for Environmental Cleanup.  

National Technical Information Service (NTIS)

Two areas of research are described: (1) Studies of the surface and photochemical properties of TiO2 surfaces; (2) study of the factors influencing the use of carbon nanotubes for adsorption. This work connects to the use of TiO2 and carbon nanotubes for ...

J. T. Yates

2001-01-01

242

Correlation between dispersion properties of TiO2 colloidal sols and photoelectric characteristics of TiO2 films.  

PubMed

TiO2 film for use as dye-sensitized solar cell was prepared using the TiO2 colloidal sols (unpeptized sol and peptized sol). The optical properties and photocurrent-voltage characteristics of the resultant films were investigated. The optical transmittance of TiO2 thin film prepared from the peptized colloidal sol was over 90%, while that of TiO2 film from the unpeptized sol was under 80%. The TiO2 photoelectrode prepared from the peptized colloidal sol showed low photoelectric conversion efficiency (eta), 1.30%, whereas the efficiency of photoelectrode from the unpeptized sol was 2.21%. The high optical transmittance and low conversion efficiency of TiO2 film from the peptized sol are discussed in terms of dense microstructure due to the drying nature of well-dispersed colloidal sol. PMID:15464814

Jung, Hyun Suk; Lee, Sang-Wook; Kim, Jin Young; Hong, Kug Sun; Lee, Young Cheol; Ko, Kyung Hyun

2004-11-15

243

Field solar E. coli inactivation in the absence and presence of TiO 2: is UV solar dose an appropriate parameter for standardization of water solar disinfection?  

Microsoft Academic Search

Evaluation of solar treatment in the absence and presence of TiO2 has been made to assess its effectiveness in reducing bacterial load with respect to drinking water standards.Field experiments under direct solar radiation were carried out using a compound parabolic collector (CPC) placed at the Swiss Federal Institute of Technology (EPFL), Lausanne, Switzerland. Water contaminated with E. coli K12 was

Angela-Guiovana Rincón; Cesar Pulgarin

2004-01-01

244

Solar photocatalytic degradation of methylene blue in carbon-doped TiO 2 nanoparticles suspension  

Microsoft Academic Search

Carbon-doped TiO2 nanoparticles were prepared by sol–gel auto-combustion method and characterized by X-ray diffraction (XRD), X-ray photoelectron spectra (XPS), Brunauer–Emmett–Teller method (BET), UV–vis diffuses reflectance spectroscopy (DRS). UV–vis diffuse reflectance spectra showed that carbon-doped TiO2 exhibited obvious absorption in the visible light range. The visible light photocatalytic activity of carbon-doped TiO2 was ascribed to the presence of oxygen vacancy state

Qi Xiao; Jiang Zhang; Chong Xiao; Zhichun Si; Xiaoke Tan

2008-01-01

245

Oxidative stress-mediated cytotoxicity and apoptosis induction by TiO2 nanofibers in HeLa cells.  

PubMed

Titanium dioxide nanoparticles are increasingly being used in pharmaceutical and cosmetic products. The high aspect ratio of fibrous nanomaterials, such as carbon nanotubes and TiO(2) nanofibers (TiO(2)NFs), similar to the one used in this study makes them an attractive structural material and has attracted a lot of attention due to their possible negative health effects as suggested by their morphological similarities with asbestos. In the present study, therefore, toxicity of TiO(2)NFs was evaluated in human cervical adenocarcinoma HeLa cells. The TEM and XRD analyses showed that TiO(2)NFs used in this study are pure with uniform diameter of around 200 nm, and their length to width aspect ratio ranged between 5 and 15. Exposure of HeLa cells to TiO(2)NFs induced significant cytotoxicity even at doses as low as 2 ?g/ml. The intracellular uptake of TiO(2)NFs in cells was shown by Alizarin Red S (ARS) labeled nanofibers. The mechanism of toxicity is mainly due to the induction of cellular oxidative stress, as revealed by elevated ROS levels, reduced antioxidant levels, and increased lipid peroxidation leading to apoptosis. The cell cycle analysis indicated G(2)/M cell cycle arrest in the cells exposed to TiO(2)NF. TiO(2)NFs treatment to HeLa cells resulted in increased expression of proapoptotic proteins Bax with an increase in cytosolic Cytochrome-C and inhibition of anti-apoptotic protein Bcl-2. Our results revealed the potential mechanism of cellular effects of TiO(2)NFs. PMID:22446064

Ramkumar, Kunga Mohan; Manjula, Chinnasamy; Gnanakumar, Georgepeter; Kanjwal, Muzafar A; Sekar, Thillai V; Paulmurugan, Ramasamy; Rajaguru, Palanisamy

2012-03-07

246

TiO2 nanotube structures for enhanced cell and biological functionality  

NASA Astrophysics Data System (ADS)

Nanostructures have pronounced effects on biological processes such as growth of cells and their functionality. Advances in biomaterial surface structure and design have resulted in improved tissue engineering. Nanotechnology can be utilized for optimization of titanium implants with a formation of vertically aligned TiO2 nanotube arrays on the implant surface. The anodic oxidation of the titanium implant surface to form a TiO2 nanotube array involves electrochemical processes and self assembly. In this paper, the mechanism of nanotube formation, nanotube bio-characteristics, and their emerging role in soft and hard tissue engineering as well as in regenerative medicine will be reviewed, and the beneficial effects of surface nanotubes on cell adhesion, proliferation, and functionality will be discussed in relation to potential orthopedics applications.

Brammer, Karla S.; Oh, Seunghan; Frandsen, Christine J.; Jin, Sungho

2010-04-01

247

Titanium Dioxide (TiO2) Nanoparticles Induce JB6 Cell Apoptosis Through Activation of the Caspase8\\/Bid and Mitochondrial Pathways  

Microsoft Academic Search

Titanium dioxide (TiO2), a commercially important material, is used in a wide variety of products. Although TiO2 is generally regarded as nontoxic, the cytotoxicity, pathogenicity, and carcinogenicity of TiO2 nanoparticles have been recently recognized. The present study investigated TiO2 nanoparticle-induced cell apoptosis and molecular mechanisms involved in this process in a mouse epidermal (JB6) cell line. Using the 3-(4,5-dimethylthiazolyl-2)-2, 5-diphenyltetrazolium

Jinshun Zhao; Linda Bowman; Xingdong Zhang; Val Vallyathan; Shih-Houng Young; Vincent Castranova; Min Ding

2009-01-01

248

TiO 2 nanotube structures for enhanced cell and biological functionality  

Microsoft Academic Search

Nanostructures have pronounced effects on biological processes such as growth of cells and their functionality. Advances in\\u000a biomaterial surface structure and design have resulted in improved tissue engineering. Nanotechnology can be utilized for\\u000a optimization of titanium implants with a formation of vertically aligned TiO2 nanotube arrays on the implant surface. The anodic oxidation of the titanium implant surface to form

Karla S. Brammer; Seunghan Oh; Christine J. Frandsen; Sungho Jin

2010-01-01

249

Ta-doped TiO2 nanotubes for enhanced solar-light photoelectrochemical water splitting.  

PubMed

A little dopey: Ta-doped titania (TiO2) nanotube (NT) arrays can be grown by electrochemical anodization onto low-Ta-concentration (0.03-0.4?at?% Ta) Ti-Ta alloys. Under optimized conditions (0.1?at?% Ta, annealing at 650?°C and 7??m thickness), Ta-doped TiO2 NT arrays show a significantly enhanced activity in photoelectrochemical water splitting under simulated sunlight conditions (see figure). PMID:23519978

Altomare, Marco; Lee, Kiyoung; Killian, Manuela S; Selli, Elena; Schmuki, Patrik

2013-03-20

250

Photocatalytic Destruction of Organic Dye Using TiO2 and Solar Energy  

Microsoft Academic Search

Figure 4 on page 354 appeared erroneously as a repeat of Figure 2. The correct Figure 4 is given below. Figure 4. Plot of concentration of MG vs. time during each experimental treatment: (a) MG solution is kept in the dark in the presence of TiO2; (b) MG solution treated with early afternnon sunlight in theabssence of TiO2; (c) MG

K. D. Giglio; D. B. Green; B. Hutchinson

1995-01-01

251

Modeling the reactive sputter deposition of N-doped TiO2 for application in dye-sensitized solar cells: Effect of the O2 flow rate on the substitutional N concentration  

NASA Astrophysics Data System (ADS)

In this paper an original numerical model, based on the standard Berg model, was used to simulate the growth mechanism of N-doped TiO2 deposited at different O2 concentrations in the reactive gas mixture. For evaluation of the numerical model, films were deposited in the same conditions as those used in the numerical approach. Films were analyzed by profilometry, optical spectrophotometry, Rutherford back-scattering spectroscopy (RBS) and X-ray photoelectron spectroscopy (XPS). Results show that oxidation of TiN plays a fundamental role for incorporation of substitutional N in the TiO2 lattice and the overall structure of the films, as well as, the chemical composition obtained from numerical model is in agreement to experimental data.

Duarte, D. A.; Sagás, J. C.; da Silva Sobrinho, A. S.; Massi, M.

2013-03-01

252

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

2011-09-12

253

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

2012-11-21

254

TiO2 coating promotes human mesenchymal stem cell proliferation without the loss of their capacity for chondrogenic differentiation.  

PubMed

Human mesenchymal stem cells (hMSCs) are used in applications, which may require a large amount of cells; therefore, efficient expansion of the cells is desired. We studied whether TiO2 coating on plastic cell culture dishes could promote proliferation of hMSCs without adverse effects in chondrogenic differentiation. TiO2-films were deposited on polystyrene dishes and glass coverslips using an ultrashort pulsed laser deposition technique. Human MSCs from three donors were expanded on them until 95% confluence, and the cells were evaluated by morphology, immunocytochemistry and quantitative RT-PCR (qRT-PCR). The chondrogenic differentiation in pellets was performed after cultivation on TiO2-coated dishes. Chondrogenesis was evaluated by histological staining of proteoglycans and type II collagen, and qRT-PCR. Human MSC-associated markers STRO-1, CD44, CD90 and CD146 did not change after expansion on TiO2-coated coverslips. However, the cell number after a 48h-culture period was significantly higher on TiO2-coated culture dishes. Importantly, TiO2 coating caused no significant differences in the proteoglycan and type II collagen staining of the pellets, or the expression of chondrocyte-specific genes in the chondrogenesis assay. Thus, the proliferation of hMSCs could be significantly increased when cultured on TiO2-coated dishes without weakening their chondrogenic differentiation capacity. The transparency of TiO2-films allows easy monitoring of the cell growth and morphology under a phase-contrast microscope. PMID:23592549

Kaitainen, Salla; Mähönen, Anssi J; Lappalainen, Reijo; Kröger, Heikki; Lammi, Mikko J; Qu, Chengjuan

2013-04-17

255

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

2007-12-19

256

The change in the spectral reflectivity and integral absorption coefficient of TiO2 powders under the influence of simulated solar radiation  

NASA Astrophysics Data System (ADS)

Results are presented of experimental measurements of changes in the spectral reflectivity and integral absorption coefficient of pressed powders of the pigment TiO2, which is used in spacecraft reflective thermal protection coatings, under simulated solar irradiation. Specimens of the pressed TiO2 rutile powders were irradiated in a 10 to the -7th torr vacuum by a DKSR-3000 xenon lamp at an ultraviolet intensity 9.5 times that of the sun. The shape of the reflectance spectrum of TiO2 powder is observed to vary as a function of the amount of radiation received, with significant decreases in reflectivity in the visible and infrared regions. Corresponding increases in integral absorptivity are also observed as a function of exposure time, while exposure at atmospheric pressures inhibits the induced absorption in the infrared. Results are explained in terms of the photolysis of TiO2 by solar irradiation.

Mikhailov, M. M.; Dvoretskii, M. I.

257

Structural, optical, and electrical properties of p-type NiO films and composite TiO 2/NiO electrodes for solid-state dye-sensitized solar cells  

NASA Astrophysics Data System (ADS)

p-Type nickel oxide thin films were prepared by sol-gel method, and their structural, optical and electrical properties were investigated. The Ni(OH) 2 sol was formed from nickel (II) acetate tetrahydrate, Ni(CH 3COO) 2·4H 2O, in a mixture of alcohol solution and poly(ethylene glycol), and deposited on an ITO substrate by spin coating followed by different heat treatments in air (50-800 °C). The formation and composition of NiO thin film was justified by EDX analysis. It is found that the thickness of the NiO film calcined at 450 °C for 1 h is about 120 nm with average particle size of 22 nm, and high UV transparency (˜75%) in the visible region is also observed. However, the transmittance is negligible for thin films calcined at 800 °C and below 200 °C due to larger particle size and the amorphous characteristics, respectively. Moreover, the composite electrode comprising n-type TiO 2 and p-type NiO is fabricated. The current-voltage ( I- V) characteristics of the composite TiO 2/NiO electrode demonstrate significant p-type behavior by the shape of the rectifying curve in dark. The effect of calcination temperature on the rectification behavior is also discussed.

Lee, Yi-Mu; Hsu, Cheng-Hsing; Chen, Hung-Wei

2009-02-01

258

Photocatalytic Destruction of an Organic Dye Using TiO2 and Solar Energy.  

ERIC Educational Resources Information Center

|Describes a general chemistry experiment that is carried out in sunlight to illustrate the ability of TiO2 to act as a photocatalyst by mineralizing an organic dye into carbon dioxide. Details about the construction of the reactor system used to perform this experiment are included. (DDR)|

Giglio, Kimberly D.; And Others

1995-01-01

259

Photocatalytic degradation of organic compounds in aqueous solution by a TiO 2-coated rotating-drum reactor using solar light  

Microsoft Academic Search

This paper deals with the degradation of aqueous phenol by a newly proposed rotating-drum reactor coated with a TiO2 photocatalyst, in which TiO2 powders loaded with Pt are immobilized on the outer surface of a glass-drum. The reactor can receive solar light and oxygen from the atmosphere effectively. It was shown experimentally that phenol can be decomposed rapidly by this

Lianfeng Zhang; Tatsuo Kanki; Noriaki Sano; Atsushi Toyoda

2001-01-01

260

Photocatalytic degradation of organic dyes under solar light irradiation combined with Er 3+:YAlO 3\\/Fe and Co-doped TiO 2 coated composites  

Microsoft Academic Search

In order to extend the photocatalytic performance of TiO2, two new photocatalysts of Er3+:YAlO3\\/Fe- and Co-doped TiO2 coated composites were prepared by the sol–gel process and characterized by XRD and TG-DTA. And then, their photocatalytic activities through the degradation of azo fuchsine under solar light irradiation were evaluated by HPLC techniques and UV–vis spectra. The influencing factors such as the

Rui Xu; Jia Li; Jun Wang; Xiaofang Wang; Bin Liu; Baoxin Wang; Xiaoyu Luan; Xiangdong Zhang

2010-01-01

261

Antibacterial activity and increased bone marrow stem cell functions of Zn-incorporated TiO2 coatings on titanium.  

PubMed

In this work, zinc was incorporated into TiO2 coatings on titanium by plasma electrolytic oxidation to obtain the implant with good bacterial inhibition ability and bone-formability. The porous and nanostructured Zn-incorporated TiO2 coatings are built up from pores smaller than 5 ?m and grains 20-100 nm in size, in which the element Zn exists as ZnO. The results obtained from the antibacterial studies suggest that the Zn-incorporated TiO2 coatings can greatly inhibit the growth of both Staphylococcus aureus and Escherichia coli, and the ability to inhibit bacteria can be improved by increasing the Zn content in the coatings. Moreover, the in vitro cytocompatibility evaluation demonstrates that the adhesion, proliferation and differentiation of rat bone marrow stem cells (bMSC) on Zn-incorporated coatings are significantly enhanced compared with Zn-free coating and commercially pure Ti plate, and no cytotoxicity appeared on any of the Zn-incorporated TiO2 coatings. Moreover, bMSC express higher level of alkaline phosphatase activity on Zn-incorporated TiO2 coatings and are induced to differentiate into osteoblast cells. The better antibacterial activity, cytocompatibility and the capability to promote bMSC osteogenic differentiation of Zn-incorporated TiO2 coatings may be attributed to the fact that Zn ions can be slowly and constantly released from the coatings. In conclusion, innovative Zn-incorporated TiO2 coatings on titanium with excellent antibacterial activity and biocompatibility are promising candidates for orthopedic and dental implants. PMID:22023752

Hu, H; Zhang, W; Qiao, Y; Jiang, X; Liu, X; Ding, C

2011-09-29

262

Nanostructured N-doped TiO2 marigold flowers for an efficient solar hydrogen production from H2S.  

PubMed

Nitrogen-doped TiO2 nanostructures in the form of marigold flowers have been synthesized for the first time using a facile solvothermal method. The structural analysis has shown that such an N-doped TiO2 system crystallizes in the anatase structure. The optical absorption spectra have clearly shown the shift in the absorption edge towards the visible-light range, which indicates successful nitrogen doping. The nitrogen doping has been further confirmed by photoluminescence and photoemission spectroscopy. Microscopy studies have shown the thin nanosheets (petals) of N-TiO2 with a thickness of ?2-3 nm, assembled in the form of the marigold flower with a high surface area (224 m(2) g(-1)). The N-TiO2 nanostructure with marigold flowers is an efficient photocatalyst for the decomposition of H2S and production of hydrogen under solar light. The maximum hydrogen evolution obtained is higher than other known N-TiO2 systems. It is noteworthy that photohydrogen production using the unique marigold flowers of N-TiO2 from abundant H2S under solar light is hitherto unattempted. The proposed synthesis method can also be utilized to design other hierarchical nanostructured N-doped metal oxides. PMID:23958807

Chaudhari, Nilima S; Warule, Sambhaji S; Dhanmane, Sushil A; Kulkarni, Milind V; Valant, Matjaz; Kale, Bharat B

2013-08-19

263

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

2012-10-01

264

Codeposition of TiO 2\\/CdS films electrode for photo-electrochemical cells  

Microsoft Academic Search

A densely packed TiO2 thin film onto an indium doped–tin oxide (ITO) substrate was synthesized at room temperature by chemical deposition and a CdS thin film was deposited onto the pre-deposited TiO2 film by a doctor blade route (powder of CdS was obtained from chemical deposition). TiO2\\/CdS film was annealed at 300°C for 1h in air for crystallinity improvement. The

R. S. Mane; Moon-Young Yoon; Hoeil Chung; Sung-Hwan Han

2007-01-01

265

Enhanced Carrier Transport of N-Doped TiO2 for Photoelectrochemical Cells  

NASA Astrophysics Data System (ADS)

The carrier transport kinetics of the TiO2 film doped with N (TiO2:N) were investigated by measuring the current and open circuit potential transients under light on/off illumination. These measurements were compared to an undoped film. The N in TiO2 not only shifted the light absorption into a longer wavelength region (known effect) but also enhanced the carrier transport. The combination of these two effects improved the photogeneration of the electron-hole pairs and suppressed their recombination, resulting in much better photoelectrochemical performance, compared to that of the undoped TiO2.

Kim, Jae-Hong; Yun, Tae Kwan; Bae, Jae-Yung; Ahn, Kwang-Soon

2009-12-01

266

Dye Sensitized Solar Cells  

PubMed Central

Dye sensitized solar cell (DSSC) is the only solar cell that can offer both the flexibility and transparency. Its efficiency is comparable to amorphous silicon solar cells but with a much lower cost. This review not only covers the fundamentals of DSSC but also the related cutting-edge research and its development for industrial applications. Most recent research topics on DSSC, for example, applications of nanostructured TiO2, ZnO electrodes, ionic liquid electrolytes, carbon nanotubes, graphene and solid state DSSC have all been included and discussed.

Wei, Di

2010-01-01

267

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

268

RGD peptide immobilized on TiO2 nanotubes for increased bone marrow stromal cells adhesion and osteogenic gene expression.  

PubMed

Recently, TiO(2) nanotube layers are widely used in orthopedics and dental applications because of their good promotion effect on bone cells. Furthermore, peptide sequences such as arginine-glycine-aspartic acid are used to modify Ti implant for binding to cell surface integrins through motif. In this study, a cellular adhesive peptide of arginine-glycine-aspartic acid-cysteine (RGDC) was immobilized onto anodized TiO(2) nanotubes on Ti to examine its in vitro responses on rat bone marrow stromal cells (BMSCs). Materials were characterized by scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy techniques. High-resolution C1s scans suggested the presence of RGDC on the surface and SEM images confirmed the nanotubes were not destroyed after modification. BMSCs adhesion and osteogenic gene expression were detected in TiO(2) nanotube layers with and without RGDC modification by fluorescence microscopy, confocal laser scanning microscopy, SEM, and realtime polymerase chain reaction (Real-time PCR). Results showed that the TiO(2) nanotube layers immobilized with RGDC increased BMSCs adhesion compared to nonfunctionalized nanotubes after 4 h of cultivation. Furthermore, the osteogenic gene expression of BMSCs was dramatically enhanced on the TiO(2) nanotube layers immobilized with RGDC (10 mM) compared to the TiO(2) nanotube layers immobilized with RGDC (1 mM) and non-functionalized anodized Ti. Our results from in vitro study provided evidence that Ti anodized to possess nanotubes and then further functionalized with RGDC should be further studied for the design of better biomedical implant surfaces. PMID:22143905

Cao, Xin; Yu, Wei-qiang; Qiu, Jing; Zhao, Yan-fang; Zhang, Yi-lin; Zhang, Fu-qiang

2011-12-06

269

Preparation, electrochemical, photoelectrochemical, and solid state characteristics of In-incorporated TiO2 thin films for solar energy applications  

NASA Astrophysics Data System (ADS)

Pure and indium incorporated titanium dioxide thin films were prepared using the spray/CVD technique. The incorporation of foreign atoms in the oxide film affects both the photovoltaic and photoelectrochemical characteristics of the heterojunction n-Si/TiO2. The presence of In in the titanium oxide matrix up to a film thickness of 100 nm had no effect on the transmittance of the oxide in the visible region. The conductivity and bandgap energy were found to increase with In-incorporation. The increased conductivity of the indium-containing oxide films is reflected in the improved photovoltaic properties of the prepared n-Si/TiO2- In solar cells. The photoelectrochemical properties of the prepared photoanodes revealed that the charge transfer step at the oxide/electrolyte interface leads to the deterioration of the device quality. A model for the effect of indium incorporation on the band structure of the TiO2 semiconducting film was suggested.

Badawy, Waheed A.; El-Giar, Emad M.

1991-12-01

270

Nanostructured N-doped TiO2 marigold flowers for an efficient solar hydrogen production from H2S  

NASA Astrophysics Data System (ADS)

Nitrogen-doped TiO2 nanostructures in the form of marigold flowers have been synthesized for the first time using a facile solvothermal method. The structural analysis has shown that such an N-doped TiO2 system crystallizes in the anatase structure. The optical absorption spectra have clearly shown the shift in the absorption edge towards the visible-light range, which indicates successful nitrogen doping. The nitrogen doping has been further confirmed by photoluminescence and photoemission spectroscopy. Microscopy studies have shown the thin nanosheets (petals) of N-TiO2 with a thickness of ~2-3 nm, assembled in the form of the marigold flower with a high surface area (224 m2 g-1). The N-TiO2 nanostructure with marigold flowers is an efficient photocatalyst for the decomposition of H2S and production of hydrogen under solar light. The maximum hydrogen evolution obtained is higher than other known N-TiO2 systems. It is noteworthy that photohydrogen production using the unique marigold flowers of N-TiO2 from abundant H2S under solar light is hitherto unattempted. The proposed synthesis method can also be utilized to design other hierarchical nanostructured N-doped metal oxides.Nitrogen-doped TiO2 nanostructures in the form of marigold flowers have been synthesized for the first time using a facile solvothermal method. The structural analysis has shown that such an N-doped TiO2 system crystallizes in the anatase structure. The optical absorption spectra have clearly shown the shift in the absorption edge towards the visible-light range, which indicates successful nitrogen doping. The nitrogen doping has been further confirmed by photoluminescence and photoemission spectroscopy. Microscopy studies have shown the thin nanosheets (petals) of N-TiO2 with a thickness of ~2-3 nm, assembled in the form of the marigold flower with a high surface area (224 m2 g-1). The N-TiO2 nanostructure with marigold flowers is an efficient photocatalyst for the decomposition of H2S and production of hydrogen under solar light. The maximum hydrogen evolution obtained is higher than other known N-TiO2 systems. It is noteworthy that photohydrogen production using the unique marigold flowers of N-TiO2 from abundant H2S under solar light is hitherto unattempted. The proposed synthesis method can also be utilized to design other hierarchical nanostructured N-doped metal oxides. Electronic supplementary information (ESI) available: GC-MS graph of the filtrate obtained in solvothermal reaction after 16 h and FESEM images without guanidine carbonate for 16 h. See DOI: 10.1039/c3nr02975a

Chaudhari, Nilima S.; Warule, Sambhaji S.; Dhanmane, Sushil A.; Kulkarni, Milind V.; Valant, Matjaz; Kale, Bharat B.

2013-09-01

271

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

272

In vitro cytotoxicity and genotoxicity studies of titanium dioxide (TiO2) nanoparticles in Chinese hamster lung fibroblast cells.  

PubMed

There are increasing safety concerns about the development and abundant use of nanoparticles. The unique physical and chemical characteristics of titanium dioxide (TiO2) nanoparticles result in different chemical and biological activities compared to their larger micron-sized counterparts, and can subsequently play an important role in influencing toxicity. Therefore, our objective was to investigate the cytotoxicity and genotoxicity of commercially available TiO2 nanoparticles with respect to their selected physicochemical properties, as well as the role of surface coating of these nanoparticles. While all types of tested TiO2 samples decrease cell viability in a mass-based concentration- and size-dependent manner, the polyacrylate-coated nano-TiO2 product was only cytotoxic at higher concentrations. A similar pattern of response was observed for induction of apoptosis/necrosis, and no DNA damage was detected in the polyacrylate-coated nano-TiO2 model. Given the increasing production of TiO2 nanoparticles, toxicological studies should take into account the physiochemical properties of these nanoparticles that may help researchers to develop new nanoparticles with minimum toxicity. PMID:23274916

Hamzeh, Mahsa; Sunahara, Geoffrey I

2012-12-28

273

Electrogenerated chemiluminescence of novel TiO2/CdS nanocomposites for sensitive assays of cancer cells.  

PubMed

A novel TiO2/CdS nanocomposite was prepared and used to fabricate an electrochemiluminescence (ECL) biosensor for the detection of cancer cells for the first time. The nanocomposite exhibited a strong cathodic ECL signal. Folic acid for targeting cell membranes was bound to a TiO2/CdS/3-aminopropyltriethoxysilane film, and specific recognition of folic acid to targeting cells was achieved, leading to a significant decrease in ECL intensity. The decrease in ECL signal was logarithmically related to the cell concentration in the range of 150-9600cellsmL(-1). The ECL biosensor could provide a sensitive, selective, and convenient approach for early and accurate detection of cancer cells. PMID:23872009

Huang, Tingyu; Jie, Guifen

2013-07-16

274

TiO 2-based solar photocatalytic detoxification of water containing organic pollutants. Case studies of 2,4-dichlorophenoxyaceticacid (2,4-D) and of benzofuran  

Microsoft Academic Search

The detoxification of water has been performed at a pilot scale under solar irradiation at the Plataforma Solar de Almeria (Spain). The photoreactor consisted of a tank (247l) connected to compound parabolic collectors (CPCs) (147l), through which the aqueous suspension of titania (0.2g\\/l of TiO2 Degussa P-25) was circulated at a flow-rate of 3.5m3\\/h. Two model molecules have been chosen:

Jean-Marie Herrmann; Jean Disdier; Pierre Pichat; Sixto Malato; Julian Blanco

1998-01-01

275

Solar photocatalytic degradation of gaseous formaldehyde by sol–gel TiO 2 thin film for enhancement of indoor air quality  

Microsoft Academic Search

Solar photocatalytic degradation of formaldehyde in the gaseous phase has been investigated. The tested photoreactor is made of a borosilicate glass tube with the inner surface coated with a sol–gel TiO2 thin film. In a pseudo-first-order Langmuir–Hinshelwood (L–H) model, the maximum reaction rate constant obtained is 0.148 min?1 under an exposure to sunlight with solar UVA irradiance of 1.56 mW\\/cm2.

W. H Ching; Michael Leung; Dennis Y. C Leung

2004-01-01

276

Sol-Gel-derived TiO2-SiO2 implant coatings for direct tissue attachment. Part II: Evaluation of cell response.  

PubMed

Silica-releasing sol-gel derived TiO2-SiO2 coatings with tailored nanostructure were evaluated in fibroblast and osteoblast cell cultures. The adhesion of both fibroblasts and osteoblasts proceeded within two hours. The highest fibroblast proliferation activities were observed on the TiO2-SiO2 (70:30) and (30:70) coatings. However, the cell layer on TiO2-SiO2 (30:70) coating was disordered. Prolonged osteoblast activity was observed on the coatings as a function of increased amount of released silica. At day 21 the surfaces were fully covered by the calcified nodules and extracellular matrix except for the coatings TiO2-SiO2 (10:90) i.e. having the highest SiO2 amount. The results suggested that TiO2-SiO2 (70:30) was the best for fibroblasts and TiO2-SiO2 (30:70) for osteoblasts. The applicability of the sol-gel derived TiO2 and TiO2-SiO2 coatings as an alternative for the calcium phosphate based implant coatings are discussed. PMID:17483880

Areva, Sami; Aäritalo, Virpi; Tuusa, Sari; Jokinen, Mika; Lindén, Mika; Peltola, Timo

2007-08-01

277

Direct imprinting of ordered and dense TiO 2 nanopore arrays by using a soft template for photovoltaic applications  

NASA Astrophysics Data System (ADS)

• Ordered TiO 2 nanopore arrays can be imprinted by using a PMMA/PDMS template. • Vacuum-assisted infiltration ensures complete filling of PMMA into AAO pores. • Freeze-drying assists in obtaining PMMA nanorods with higher aspect ratio. • The diameter of the imprinted TiO 2 nanopores can be adjusted from 30 nm to 300 nm. • The imprinted TiO 2 nanopore arrays can enhance solar cell performance.

Zhong, Peng; Que, Wenxiu; Hu, X.

2011-09-01

278

Titanium Dioxide (TiO2) Nanoparticles Preferentially Induce Cell Death in Transformed Cells in a Bak/Bax-Independent Fashion  

PubMed Central

While the cytotoxic effects of titanium dioxide (TiO2) nanoparticles have been under intense investigation, the molecular mechanisms of this cytotoxicity remain unknown. Here we investigated the influence of oncogenic transformation and a major apoptotic signaling pathway on cellular responses to TiO2 nanoparticles. Isogenic wild-type (WT) and apoptosis-resistant (Bak?/?Bax?/?) cell lines with and without tumorigenic transformation were examined. TiO2 nanoparticles preferentially reduced viability of tumorigenic cells in a dose-dependent fashion compared with their untransformed counterparts. Importantly, the elevated cytotoxicity of TiO2 nanoparticles was independent of a major Bak/Bax-dependent apoptosis pathway. Because transformation does not affect cellular fluid-phase endocytosis or nanoparticle uptake, it is likely that the increased cytotoxicity in tumor cells is due to the interaction between TiO2 nanoparticles and the lysosomal compartment. Overall, our data indicate that TiO2 nanoparticles induce cytotoxicity preferentially in transformed cells independent of a major apoptotic signaling pathway.

Zhu, Yanglong; Eaton, John W.; Li, Chi

2012-01-01

279

The detrimental influence of bacteria (E. coli, Shigella and Salmonella) on the degradation of organic compounds (and vice versa) in TiO(2) photocatalysis and near-neutral photo-Fenton processes under simulated solar light.  

PubMed

TiO(2) photocatalytic and near-neutral photo-Fenton processes were tested under simulated solar light to degrade two models of natural organic matter - resorcinol (R) (which should interact strongly with TiO(2) surfaces) and hydroquinone (H) - separately or in the presence of bacteria. Under similar oxidative conditions, inactivation of Escherichia coli, Shigella sonnei and Salmonella typhimurium was carried out in the absence and in the presence of 10 mg L(-1) of R and H. The 100% abatement of R and H by using a TiO(2) photocatalytic process in the absence of bacteria was observed in 90 min for R and in 120 min for H, while in the presence of microorganisms abatement was only of 55% and 35% for R and H, respectively. Photo-Fenton reagent at pH 5.0 completely removed R and H in 40 min, whereas in the presence of microorganisms their degradation was of 60% to 80%. On the other hand, 2 h of TiO(2) photocatalytic process inactivated S. typhimurium and E. coli cells in three and six orders of magnitude, respectively, while S. sonnei was completely inactivated in 10 min. In the presence of R or H, the bacterial inactivation via TiO(2) photocatalysis was significantly decreased. With photo-Fenton reagent at pH 5 all the microorganisms tested were completely inactivated in 40 min of simulated solar light irradiation in the absence of organics. When R and H were present, bacterial photo-Fenton inactivation was less affected. The obtained results suggest that in both TiO(2) and iron photo-assisted processes, there is competition between organic substances and bacteria simultaneously present for generated reactive oxygen species (ROS). This competition is most important in heterogeneous systems, mainly when there are strong organic-TiO(2) surface interactions, as in the resorcinol case, suggesting that bacteria-TiO(2) interactions could play a key role in photocatalytic cell inactivation processes. PMID:22370626

Moncayo-Lasso, Alejandro; Mora-Arismendi, Luis Enrique; Rengifo-Herrera, Julián Andrés; Sanabria, Janeth; Benítez, Norberto; Pulgarin, César

2012-02-28

280

Photocatalytic degradation and mineralization of microcystin-LR under UV-A, solar and visible light using nanostructured nitrogen doped TiO2.  

PubMed

In an attempt to face serious environmental hazards, the degradation of microcystin-LR (MC-LR), one of the most common and more toxic water soluble cyanotoxin compounds released by cyanobacteria blooms, was investigated using nitrogen doped TiO(2) (N-TiO(2)) photocatalyst, under UV-A, solar and visible light. Commercial Degussa P25 TiO(2), Kronos and reference TiO(2) nanopowders were used for comparison. It was found that under UV-A irradiation, all photocatalysts were effective in toxin elimination. The higher MC-LR degradation (99%) was observed with Degussa P25 TiO(2) followed by N-TiO(2) with 96% toxin destruction after 20 min of illumination. Under solar light illumination, N-TiO(2) nanocatalyst exhibits similar photocatalytic activity with that of commercially available materials such as Degussa P25 and Kronos TiO(2) for the destruction of MC-LR. Upon irradiation with visible light Degussa P25 practically did not show any response, while the N-TiO(2) displayed remarkable photocatalytic efficiency. In addition, it has been shown that photodegradation products did not present any significant protein phosphatase inhibition activity, proving that toxicity is proportional only to the remaining MC-LR in solution. Finally, total organic carbon (TOC) and inorganic ions (NO(2)(-), NO(3)(-) and NH(4)(+)) determinations confirmed that complete photocatalytic mineralization of MC-LR was achieved under both UV-A and solar light. PMID:22169146

Triantis, T M; Fotiou, T; Kaloudis, T; Kontos, A G; Falaras, P; Dionysiou, D D; Pelaez, M; Hiskia, A

2011-11-22

281

Structural effects of TiO2 nanoparticles and doxorubicin on DNA and their antiproliferative roles in T47D and MCF7 cells.  

PubMed

The structural changes in DNA caused by the combined effects of TiO2 nanoparticles (TiO2 NPs) and doxorubicin (DOX) were investigated along with their corresponding inhibitory roles in the growth of T47D and MCF7 cells. The UV-visible titration studies showed that DOX+ TiO2 NPs could form a novel complex with DNA. The data also reveal that the TiO2-DOX complex forms through a 1:4 stoichiometric ratio in solution. The values of binding constants reveal that DOX+TiO2 NPs interact more strongly with DNA as compared to TiO2 NPs or DOX alone. CD data show that DOX+TiO2 NPs can noticeably cause disturbance on DNA structure compared to TiO2 NPs or DOX alone, considering that DNA is relatively thermally stable in the condition used. The anticancer property of 0.3 µM DOX+ 60 µM TiO2 NPs and 0.4 µM DOX+ 670 µM TiO2 NPs by MTT assay and DAPI stain demonstrates that this combination can tremendously diminish proliferation of T47D and MCF7cells compared to DOX or TiO2 NPs alone. The UV-Vis absorption spectroscopy, flow cytometry and fluorescence microscopy experiments show much more enhancement of DOX uptake through the use of TiO2 NPs. These results reveal that DOX+TiO2 NPs could proffer a novel strategy for the development of promising and efficient chemotherapy agents. PMID:23387974

Hekmat, Azadeh; Saboury, Ali Akbar; Divsalar, Adeleh; Seyedarabi, Arefeh

2013-07-01

282

Adhesion of osteoblast-like cell on silicon-doped TiO2 film prepared by cathodic arc deposition.  

PubMed

Silicon-doped TiO2 (Si-TiO2) and pure TiO2 films were deposited on titanium substrates by cathodic arc deposition technique. The surface characteristics of the films, such as surface topography, elemental composition and wettability, were studied. About 4.6 % Si was incorporated into the Si-TiO2 films with a water contact angle of about 83°. The adhesive behaviors of osteoblast-like MG63 cells on both films were investigated through cell counting assay, immunocytochemistry, real-time PCR and western blotting analysis. Cells cultured on the Si-TiO2 films had a greater cellular viability, stronger cytoskeleton and focal adhesion, and more cellular spreading than those on the pure TiO2 films. Moreover, the expression levels of integrin ?1 and focal adhesion kinase (FAK) genes, FAK and the phosphorylation of FAK proteins were up-regulated in cells cultured on the Si-TiO2 films. These results indicated that the Si-TiO2 films possess significantly enhanced cytocompatibility and provide potential solutions for the surface modification of implants in the future. PMID:23436126

Wang, Bing; Sun, Jun-Ying; Qian, Shi; Liu, Xuan-Yong; Zhang, Shai-Lin; Dong, Sheng-Jie; Zha, Guo-Chun

2013-02-23

283

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

2012-03-23

284

Construction of protein-modified TiO2 nanoparticles for use with ultrasound irradiation in a novel cell injuring method.  

PubMed

Recently, our group discovered an alternative titanium dioxide (TiO(2)) activation method that uses ultrasound irradiation (US/TiO(2)) instead of ultraviolet irradiation. The pre-S1/S2 protein from hepatitis B virus, which recognizes liver cells, was immobilized to the surface of TiO(2) nanoparticles using an amino-coupling method. The ability of the protein-modified TiO(2) nanoparticles to recognize liver cells was confirmed by surface plasmon resonance analysis and immuno-staining analyses. After uptake of TiO(2) nanoparticles by HepG2 cancer cells, the cells were injured using this US/TiO(2) method; significant cell injury was observed at an ultrasound irradiation intensity of 0.4 W/cm(2). Together with these results, this strategy could be applied to new cell injuring systems that use ultrasound irradiation in place of photodynamic therapy in the near future. PMID:20650634

Ogino, Chiaki; Shibata, Naonori; Sasai, Ryosuke; Takaki, Keiko; Miyachi, Yusuke; Kuroda, Shun-ichi; Ninomiya, Kazuaki; Shimizu, Nobuaki

2010-07-01

285

Development of solar-driven electrochemical and photocatalytic water treatment system using a boron-doped diamond electrode and TiO2 photocatalyst.  

PubMed

A high-performance, environmentally friendly water treatment system was developed. The system consists mainly of an electrochemical and a photocatalytic oxidation unit, with a boron-doped diamond (BDD) electrode and TiO(2) photocatalyst, respectively. All electric power for the mechanical systems and the electrolysis was able to be provided by photovoltaic cells. Thus, this system is totally driven by solar energy. The treatment ability of the electrolysis and photocatalysis units was investigated by phenol degradation kinetics. An observed rate constant of 5.1 x 10(-3)dm(3)cm(-2)h(-1) was calculated by pseudo-first-order kinetic analysis for the electrolysis, and a Langmuir-Hinshelwood rate constant of 5.6 microM(-1)min(-1) was calculated by kinetic analysis of the photocatalysis. According to previous reports, these values are sufficient for the mineralization of phenol. In a treatment test of river water samples, large amounts of chemical and biological contaminants were totally wet-incinerated by the system. This system could provide 12L/day of drinking water from the Tama River using only solar energy. Therefore, this system may be useful for supplying drinking water during a disaster. PMID:19863989

Ochiai, Tsuyoshi; Nakata, Kazuya; Murakami, Taketoshi; Fujishima, Akira; Yao, Yanyan; Tryk, Donald A; Kubota, Yoshinobu

2009-10-01

286

Self-standing Hybrid Nanofibers of TiO2 and TiO2/Hydroxyapatite: Application in Photocatalytic and Photovoltatic Systems  

NASA Astrophysics Data System (ADS)

A Hybrid fibers of Hydroxyapatite TiO2, HAp/TiO2 with modified photocatalytic properties were synthesized using a template method. Liquid phase deposition (LPD) technique was employed to grow TiO2 layers on cellulose fibers, followed by deposition of HAp from a pseudo body solution, and finally heat removing the cellulose template. The resulting material has a fibrous structure, mimicking the cellulose fibers shape, and have a typical surface area of 114 m^2/g, compared to 74 m^2/g for pure TiO2 fibers. Adsorption and photocatalytic degradation tests showed that addition of HAp to TiO2 fibers increased the adsorptive from 17% to 35%. Nano particulated TiO2 fibers as one-dimensional long structures were introduced into TiO2 P25 nano particle films using co-electrophoretic deposition. This resulted in less porosity and higher roughness factor of the films that provided more favorable conditions for electron transport. The films used as the photoanode of a dye solar cell (DSC) produced 65% higher photovoltaic efficiency. TiO2 fibers can be excellent binders in single-step, organic-free electrophoretic deposition of TiO2 for DSC photoanode.

Rouhani, Parvaneh

2012-02-01

287

Behaviour of TiO 2–SiMgO x hybrid composites on the solar photocatalytic degradation of polluted air  

Microsoft Academic Search

The photocatalytic performance of TiO2–SiMgOx ceramic plates for trichloroethylene abatement in gas phase has been evaluated under sun irradiance conditions. A continuous flow Pyrex glass reactor fixed on the focus of a compound parabolic collector has been used. The performance of the hybrid photocatalyst has been evaluated as the variation of TCE conversion and reaction products formation with the solar

S. Suárez; T. L. R. Hewer; R. Portela; M. D. Hernández-Alonso; R. S. Freire; B. Sánchez

2011-01-01

288

Sensitization of nano-porous films of TiO 2 with santalin (red sandalwood pigment) and construction of dye-sensitized solid-state photovoltaic cells  

Microsoft Academic Search

Santalin, a pigment extracted from red sandalwood strongly surface complex to TiO2, sensitizing nano-porous film of TiO2 to the visible spectrum. Because of the stability of such films, dye-sensitized solid state photovoltaic cells of sandwich structure (nano-porous n-TiO2\\/santalin\\/p-type semiconductor) can be constructed by depositing p-CuI or p-CuCNS on santalin coated nano-porous films of TiO2. High stability of santalin complexed to

K Tennakone; G. R. R. A Kumara; I. R. M Kottegoda; V. P. S Perera; P. S. R. S Weerasundara

1998-01-01

289

Floating photocatalysts based on TiO 2 grafted on expanded polystyrene beads for the solar degradation of dyes  

Microsoft Academic Search

In this work, a highly active, low cost, simple and robust floating photocatalyst based on TiO2 P25 grafted on expanded polystyrene (EPS) beads was developed. SEM and TG analyses showed that ca. 18wt% of TiO2 can be permanently grafted on the surface of EPS particles. This floating photocatalyst showed high efficiency for the degradation of three different dyes, i.e. methylene

F. Magalhães; R. M. Lago

2009-01-01

290

Cyto- and genotoxicity of ultrafine TiO2 particles in cultured human lymphoblastoid cells.  

PubMed

Titanium dioxide is frequently used in the production of paints, paper, plastics, welding rod-coating material, and cosmetics, because of its low toxicity. However, recent studies have shown that nano-sized or ultrafine TiO(2) (UF-TiO(2)) (<100 nm in diameter) can generate pulmonary fibrosis and lung tumor in rats. Cytotoxicity induced by UF-TiO(2) in rat lung alveolar macrophages was also observed. This generates great concern about the possible adverse effects of UF-TiO(2) for humans. The cytotoxicity and genotoxicity of UF-TiO(2) were investigated using the methyl tetrazolium cytotoxicity (MTT) assay, the population growth assay, the apoptosis assay by flow cytometry, the cytokinesis block micronucleus (CBMN) assay, the comet assay, and the hypoxanthine-guanine phosphoribosyltransferase (HPRT) gene mutation assay. WIL2-NS cells were incubated for 6, 24 and 48 h with 0, 26, 65 and 130 microg/ml UF-TiO(2). Significant decreases in viability were seen in the MTT assay at higher doses; for example, 61, 7 and 2% relative viability at 130 microg/ml for 6, 24 and 48-h exposure (P<0.01). A dose-dependent relationship was observed, while a time-dependent relationship was seen only at the highest dose (130 microg/ml) after exposure for 24 and 48 h. Treatment with 130 microg/ml UF-TiO(2) induced approximately 2.5-fold increases in the frequency of micronucleated binucleated cells (P<0.01). In addition, a significant reduction in the cytokinesis block proliferation index was observed by the CBMN assay (P<0.05). In the comet assay, treatment with 65 microg/ml UF-TiO(2) induced approximately 5-fold increases in olive tail moment (P<0.05). In the HPRT mutation assay, treatment with 130 microg/ml UF-TiO(2) induced approximately 2.5-fold increases in the mutation frequency (P<0.05). The results of this study indicate that UF-TiO(2) can cause genotoxicity and cytotoxicity in cultured human cells. PMID:17223607

Wang, Jing J; Sanderson, Barbara J S; Wang, He

2006-12-15

291

Synthesis of poly(3-hexylthiophene) grafted TiO2 nanotube composite.  

PubMed

A composite of poly(3-hexylthiophene) (P3HT) grafted on TiO(2) nanotubes was synthesized. It was characterized using XRD, TEM, TGA, FTIR and XPS. Cyclic voltammetry (CV) was used to elucidate the electrochemical behavior and evaluate the HOMO and LUMO energy levels. Photoluminescence (PL) measurements show that the emission intensity of P3HT mixed with TiO(2) nanotubes was one third of that of random P3HT, while that of P3HT grafted onto TiO(2) nanotubes was 10% of random P3HT. The results show that the P3HT grafted onto TiO(2) nanotubes is more efficient in photoinduced charge transfer than a physical mixture of P3HT and TiO(2) nanotubes, indicating this composite has potential for the fabricating hybrid organic-inorganic solid state solar cells. PMID:19246046

Lu, Ming-De; Yang, Sze-Ming

2009-02-06

292

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

293

Cyto- and genotoxicity of ultrafine TiO 2 particles in cultured human lymphoblastoid cells  

Microsoft Academic Search

Titanium dioxide is frequently used in the production of paints, paper, plastics, welding rod-coating material, and cosmetics, because of its low toxicity. However, recent studies have shown that nano-sized or ultrafine TiO2 (UF-TiO2) (<100nm in diameter) can generate pulmonary fibrosis and lung tumor in rats. Cytotoxicity induced by UF-TiO2 in rat lung alveolar macrophages was also observed. This generates great

Jing J. Wang; Barbara J. S. Sanderson; He Wang

2007-01-01

294

Suspension plasma spraying of TiO 2 for the manufacture of photovoltaic cells  

Microsoft Academic Search

Highly porous TiO2 coatings have been produced by suspension plasma spraying on ITO coated glass substrates. The deposition process could be optimized so that fine\\/nano grained highly porous coatings were obtained. Mean crystallite sizes well below 50 nm could be achieved in the coatings for the anatase phase.Special emphasis was on the establishment of a high volume fraction of the desired

Robert Vaßen; Zeng Yi; Holger Kaßner; Detlev Stöver

2009-01-01

295

Physicochemical characteristics and cyto-genotoxic potential of ZnO and TiO2 nanoparticles on human colon carcinoma cells  

Microsoft Academic Search

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

F. Barone; B. De Berardis; L. Bizzarri; P. Degan; C. Andreoli; A. Zijno; I. De Angelis

2011-01-01

296

Fluctuation-Induced Tunneling Conductivity in TiO2 Nanoparticle Thin Films  

NASA Astrophysics Data System (ADS)

We integrate temperature-dependent dark DC conductivity measurements and theoretical modeling to elucidate the mechanism of electron transport in nanoporous TiO2, a common photoanode material for dye-sensitized solar cells (DSSCs) and solar photocatalysis. We show that fluctuation-induced tunneling conduction through contact junctions between sintered TiO2 nanoparticles can account for the temperature dependence over the entire temperature range studied. We find quantitative agreement between experimental and calculated conductivities, which span over four orders of magnitude and change with decreasing temperature from thermally activated to temperature-independent. The reported results suggest that efforts to optimize charge transport in nanoporous TiO2 thin films as a means of improving the overall efficiency of DSSCs and solar photocatalysis should focus on fabrication conditions that optimize the properties of the contact junctions between sintered TiO2 nanoparticles.

Konezny, Steven J.; Richter, Christiaan; Snoeberger, Robert C., III; Parent, Alexander R.; Brudvig, Gary W.; Schmuttenmaer, Charles A.; Batista, Victor S.

2011-03-01

297

Highly stable ternary tin-palladium-platinum catalysts supported on hydrogenated TiO2 nanotube arrays for fuel cells  

NASA Astrophysics Data System (ADS)

Herein the Pt nanocrystals were synthesized by a high-pressure methanol reduction method onto the hydrogenated TiO2 nanotube arrays pre-treated by Sn/Pd. Then Sn/Pd/Pt ternary catalysts were fabricated by hydrogen treatment. The composite catalysts with a diameter of about 18 nm were located uniformly at the inner nanotubes. The novel catalyst combined with hydrogenated TiO2 nanotube arrays exhibits excellent electro-catalytic activity and high durability. The electrochemical performance of the catalysts after 18 000 potential cycles between 0 and 1.2 V vs. RHE could reach the maximum, and the electrochemical surface area of the catalyst at 18 000 cycles is about 136 m2 g-1Pt+Pd, which is 1.3 folds than the commercial JM Pt/C (104 m2 g-1Pt). Furthermore, there is little decrease in the electrochemical surface area for the catalyst after additional 7300 potential cycles (total 24 300 cycles). In a full cell testing, the fabricated novel electrode with extra-low Pt loading (0.043 mg cm-2) generated power as 1.21 kW g-1Pt when it is used as the cathode in a fuel cell.Herein the Pt nanocrystals were synthesized by a high-pressure methanol reduction method onto the hydrogenated TiO2 nanotube arrays pre-treated by Sn/Pd. Then Sn/Pd/Pt ternary catalysts were fabricated by hydrogen treatment. The composite catalysts with a diameter of about 18 nm were located uniformly at the inner nanotubes. The novel catalyst combined with hydrogenated TiO2 nanotube arrays exhibits excellent electro-catalytic activity and high durability. The electrochemical performance of the catalysts after 18 000 potential cycles between 0 and 1.2 V vs. RHE could reach the maximum, and the electrochemical surface area of the catalyst at 18 000 cycles is about 136 m2 g-1Pt+Pd, which is 1.3 folds than the commercial JM Pt/C (104 m2 g-1Pt). Furthermore, there is little decrease in the electrochemical surface area for the catalyst after additional 7300 potential cycles (total 24 300 cycles). In a full cell testing, the fabricated novel electrode with extra-low Pt loading (0.043 mg cm-2) generated power as 1.21 kW g-1Pt when it is used as the cathode in a fuel cell. Electronic supplementary information (ESI) available. See DOI: 10.1039/c3nr01086d

Zhang, Changkun; Yu, Hongmei; Li, Yongkun; Fu, Li; Gao, Yuan; Song, Wei; Shao, Zhigang; Yi, Baolian

2013-07-01

298

Strong electronic coupling and ultrafast electron transfer between PbS quantum dots and TiO2 nanocrystalline films.  

PubMed

Hot carrier and multiple exciton extractions from lead salt quantum dots (QDs) to TiO(2) single crystals have been reported. Implementing these ideas on practical solar cells likely requires the use of nanocrystalline TiO(2) thin films to enhance the light harvesting efficiency. Here, we report 6.4 ± 0.4 fs electron transfer time from PbS QDs to TiO(2) nanocrystalline thin films, suggesting the possibility of extracting hot carriers and multiple excitons in solar cells based on these materials. PMID:22182013

Yang, Ye; Rodríguez-Córdoba, William; Xiang, Xu; Lian, Tianquan

2011-12-23

299

CdS quantum dots sensitized TiO 2 photoelectrodes  

Microsoft Academic Search

The CdS quantum dots were deposited on nanoporous TiO2 by chemical bath deposition technique to absorb the visible light in the longer wavelength region and are used as photo electrode in the dye sensitized solar cells (DSSC). The CdS quantum dots deposited on nanoporous TiO2 at 1min deposition time showed improved short circuit current density (Jsc) and open circuit voltage

K. Prabakar; Hyunwoong Seo; Minkyu Son; Heeje Kim

2009-01-01

300

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 ...

301

Highly stable ternary tin-palladium-platinum catalysts supported on hydrogenated TiO2 nanotube arrays for fuel cells.  

PubMed

Herein the Pt nanocrystals were synthesized by a high-pressure methanol reduction method onto the hydrogenated TiO2 nanotube arrays pre-treated by Sn/Pd. Then Sn/Pd/Pt ternary catalysts were fabricated by hydrogen treatment. The composite catalysts with a diameter of about 18 nm were located uniformly at the inner nanotubes. The novel catalyst combined with hydrogenated TiO2 nanotube arrays exhibits excellent electro-catalytic activity and high durability. The electrochemical performance of the catalysts after 18,000 potential cycles between 0 and 1.2 V vs. RHE could reach the maximum, and the electrochemical surface area of the catalyst at 18,000 cycles is about 136 m(2) g(-1)Pt+Pd, which is 1.3 folds than the commercial JM Pt/C (104 m(2) g(-1)Pt). Furthermore, there is little decrease in the electrochemical surface area for the catalyst after additional 7300 potential cycles (total 24,300 cycles). In a full cell testing, the fabricated novel electrode with extra-low Pt loading (0.043 mg cm(-2)) generated power as 1.21 kW g(-1)Pt when it is used as the cathode in a fuel cell. PMID:23771151

Zhang, Changkun; Yu, Hongmei; Li, Yongkun; Fu, Li; Gao, Yuan; Song, Wei; Shao, Zhigang; Yi, Baolian

2013-08-01

302

TiO2 nanotubes on Ti: Influence of nanoscale morphology on bone cell-materials interaction.  

PubMed

Ti being bioinert shows poor bone cell adhesion with an intervening fibrous capsule. Ti could be made bioactive by several methods including growing in situ TiO2 layer on Ti-surface. TiO2 nanotubes were grown on Ti surface via anodization process and the bone cell-material interactions were evaluated. Human osteoblast cell attachment and growth behavior were studied using an osteoprecursor cell line for 3, 7, and 11 days. An abundant amount of extracellular matrix (ECM) between the neighboring cells was noticed on anodized nanotube surface with filopodia extensions coming out from cells to grasp the nanoporous surface of the nanotube for anchorage. To better understand and compare cell-materials interactions, anodized nanoporous sample surfaces were etched with different patterns. Preferential cell attachment was noticed on nanotube surface compare to almost no cells in etched Ti surface. Cell adhesion with vinculin adhesive protein showed higher intensity, positive contacts on nanoporous surface and thin focal contacts on the Ti-control. Immunochemistry study with alkaline phosphatase showed enhanced osteoblastic phenotype expressions in nanoporous surface. Osteoblast proliferation was significantly higher on anodized nanotube surface. Surface properties changed with the emergence of nanoscale morphology. Higher nanometer scale roughness, low contact angle and high surface energy in nanoporous surface enhanced the osteoblast-material interactions. Mineralization study was done under simulated body fluid (SBF) with ion concentration nearly equal to human blood plasma to understand biomimetic apatite deposition behavior. Although apatite layer formation was noticed on nanotube surface, but it was nonuniform even after 21 days in SBF. PMID:18496867

Das, Kakoli; Bose, Susmita; Bandyopadhyay, Amit

2009-07-01

303

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

304

In-vitro cell tests using doxorubicin-loaded polymeric TiO2 nanotubes used for cancer photothermotherapy.  

PubMed

To determine the appropriate surfactant to be added to TiO(2) nanotubes (TNTs) for use in cancer photothermotherapy, this study measured the increase in temperature and examined the size distribution of TNT particles loaded with different surfactants during near-infrared irradiation. In addition, in-vitro cell (fluorescein isothiocyanate and MTT assay) tests were carried out to examine the cytotoxic effect of doxorubicin-loaded and polyvinyl alcohol-added TNTs (pTNTs). The mean particle size of the pTNTs was 151.8 nm with a particle size variation of less than 3 nm, which is low enough to flow through blood vessels without causing a blockage. The temperature of the pTNTs was ?47°C, which is high enough to destroy cancer cells. Doxorubicin-loaded TNTs and pTNTs in combination with a near-infrared laser showed a cell viability of 4.5% - a sufficiently high cytotoxic effect. PMID:22481062

Hong, Chanseok; An, Soyeon; Son, Mikwon; Hong, Soon Sun; Lee, Don Haeng; Lee, Chongmu

2012-06-01

305

Microscopy for Graetzel Solar cells manufacturing  

Microsoft Academic Search

The Graetzel solar cells are devices composed by two transparent glass conductive surfaces, one nanocrystalline structure interfase of TiO 2 , where a dye is introduced. The manufacturing process includes tasks where microscopy is an important tool. For instance an intermediate task is make conductive a SiO2 glass that normally is non conductive, so it is necessary take into account

Héctor I. Olmos Castillo; Gerardo Zavala Guzmán

306

Inactivation of Enterococcus faecalis by TiO2-mediated UV and solar irradiation in water and wastewater: culture techniques never say the whole truth.  

PubMed

In this work, the disinfection efficiency of water and secondary treated wastewater by means of UV-A, UV-C and solar irradiation in the presence or absence of TiO(2), using a reference strain of Enterococcus faecalis as faecal indicator, was evaluated. Operating parameters such as TiO(2) loading (0-1500 mg L(-1)), initial bacterial concentration (2 × 10(2)-10(8) CFU mL(-1)) and treatment time (up to 120 min) were assessed concerning their impact on disinfection. E. faecalis inactivation was monitored by the conventional culture method and real-time PCR. Regarding photocatalytic treatment, disinfection efficiency was improved by increasing TiO(2) concentration and bacterial inactivation took place in relatively short treatment times. Comparing the three disinfection methods, it was observed that UV-C irradiation yielded a better efficiency during water treatment than UV-A and solar irradiation. Furthermore, UV-A was more efficient than solar irradiation in the presence of the same loading of TiO(2). Regarding real wastewater, it was observed that only UV-C irradiation was capable of totally inactivating E. faecalis population in a short time. Screening the results obtained from both applied techniques (culture method and real-time PCR), there was a discrepancy, regarding the recorded time periods of total bacterial inactivation. Real-time PCR data revealed that longer periods are needed for 100% bacterial reduction during the treatments tested compared to the estimated time by culture method. This is probably attributed to the phenomenon of "viable but not culturable bacteria", caused by stressed conditions induced during disinfection experiments. Taking into account the contrast of results and in order to perform a thorough evaluation of disinfection techniques, conventional culture method should be accompanied by a DNA-based method. According to our findings, real-time PCR proved to be a reliable and accurate molecular tool for the identification and quantification of bacterial indicators, like E. faecalis, in aquatic samples after disinfection treatment. PMID:21874195

Venieri, Danae; Chatzisymeon, Efthalia; Gonzalo, Maria S; Rosal, Roberto; Mantzavinos, Dionissios

2011-08-26

307

DISINFECTION OF MUNICIPAL WASTEWATER BY TiO2 PHOTOCATALYSIS WITH UVA, VISIBLE AND SOLAR IRRADIATION AND BDD ELECTROLYSIS  

Microsoft Academic Search

The efficiency of TiO2 photocatalysis induced by ultraviolet and visible irradiation and salt-free electrolysis over boron-doped diamond electrodes to inactivate total (TC) and fecal (FC) coliforms in secondary treated municipal wastewater was evaluated. Photocatalytic experiments were conducted with two types of titania (Degussa P25 and sulfur-doped catalyst) at loadings in the range 0.1-0.5 g l-1 and three types of irradiation,

M. MELEMENI; D. STAMATAKIS; N. P. XEKOUKOULOTAKIS; D. MANTZAVINOS; N. KALOGERAKIS

308

Effect of the nanosized TiO2 particles in Pd/C catalysts as cathode materials in direct methanol fuel cells.  

PubMed

Pd-TiO2/C catalysts were prepared by impregnating titanium dioxide (TiO2) on carbon-supported Pd (Pd/C) for use as the catalyst for the oxygen reduction reaction (ORR) in direct methanol fuel cells (DMFCs). Transmission electron microscope (TEM), scanning electron microscope (SEM) and X-ray diffraction (XRD) analyses were carried to confirm the distribution, morphology and structure of Pd and TiO2 on the carbon support. In fuel cell test, we confirmed that the addition of TiO2 nanoparticles make the improved catalytic activity of oxygen reduction. The electrochemical characterization of the Pd-TiO2/C catalyst for the ORR was carried out by cyclic voltammetry (CV) in the voltage window of 0.04 V to 1.2 V with scan rate of 25 mV/s. With the increase in the crystallite size of TiO2, the peak potential for OH(ads) desorption on the surface of Pd particle shifted to higher potential. This implies that TiO2 might affect the adsorption and desorption of oxygen molecules on Pd catalyst. The performance of Pd-TiO2/C as a cathode material was found to be similar to or better performance than that of Pt/C. PMID:22121727

Choi, Mahnsoo; Han, Choonsoo; Kim, In-Tae; Lee, Ji-Jung; Lee, Hong-Ki; Shim, Joongpyo

2011-07-01

309

Improving cytocompatibility of Co28Cr6Mo by TiO2 coating: gene expression study in human endothelial cells.  

PubMed

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 Co(2+), 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

2013-07-03

310

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.

Peng, Zhaoxiang; Ni, Jiahua; Zheng, Kang; Shen, Yandong; Wang, Xiaoqing; He, Guo; Jin, Sungho; Tang, Tingting

2013-01-01

311

Studies of Interfacial Electronic Processes in Nanoporous TiO2 Thin-Films  

NASA Astrophysics Data System (ADS)

Metal-oxide nanoparticles sensitized to visible light by covalent attachment of molecular adsorbates have attracted considerable attention in recent years due their central role in technologies for solar energy conversion, including dye-sensitized solar cells (DSSCs) and solar photocatalysis. However, the mechanisms of interfacial electron transfer and subsequent electron transport induced by photoexcitation of the molecular adsorbates remain only partially understood. We report recent progress in studies of nanoporous TiO2 thin-films functionalized with molecular adsorbates, with emphasis on interfacial electron injection, molecular rectification and the mechanism of electron transport through sintered TiO2 nanoparticles in thin-films relevant to DSSCs.

Batista, Victor

2011-03-01

312

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

313

Synthesis of nanosize MCM-41 loaded with TiO2 and study of its photocatalytic activity  

NASA Astrophysics Data System (ADS)

In recent years, nanosized mesoporous materials have received significant attention due to their impact in different processes. Several diverse applications of these materials, e.g. high density magnetic recording, magnetic fluids, magnetic refrigeration as well as in photocatalysis, solar cells, photosensors, have triggered considerable research activities in the area of nanotechnology. In this work, nanosize MCM-41 was synthesized and loaded then with TiO2 using tetra butoxy titanium (TBT). As prepared TiO2 loaded materials was investigated by using X-ray diffraction (XRD), Transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR). The photocatalytic activity of the prepared TiO2 loaded MCM-41 was finally evaluated by the degradation of methyl orange under irradiation of UV light. The result showed that TiO2 loaded on nanosize MCM-41 has higher photocatalytic activity than that of TiO2.

Sadjadi, M. S.; Farhadyar, N.; Zare, K.

2009-07-01

314

Understanding the high photocatalytic activity of (B, Ag)-codoped TiO2 under solar-light irradiation with XPS, solid-state NMR, and DFT calculations.  

PubMed

The origin of the exceptionally high activity of (B, Ag)-codoped TiO(2) catalysts under solar-light irradiation has been investigated by XPS and (11)B solid-state NMR spectroscopy in conjunction with density functional theory (DFT) calculations. XPS experimental results demonstrated that a portion of the dopant Ag (Ag(3+)) ions were implanted into the crystalline lattice of (B, Ag)-codoped TiO(2) and were in close proximity to the interstitial B (B(int.)) sites, forming [B(int.)-O-Ag] structural units. In situ XPS experiments were employed to follow the evolution of the chemical states of the B and Ag dopants during UV-vis irradiation. It was found that the [B(int.)-O-Ag] units could trap the photoinduced electron to form a unique intermediate structure in the (B, Ag)-codoped TiO(2) during the irradiation, which is responsible for the photoinduced shifts of the B 1s and Ag 3d peaks observed in the in situ XPS spectra. Solid-state NMR experiments including (11)B triple-quantum and double-quantum magic angle spinning (MAS) NMR revealed that up to six different boron species were present in the catalysts and only the tricoordinated interstitial boron (T*) species was in close proximity to the substitutional Ag species, leading to formation of [T*-O-Ag] structural units. Furthermore, as demonstrated by DFT calculations, the [T*-O-Ag] structural units were responsible for trapping the photoinduced electrons, which prolongs the life of the photoinduced charge carriers and eventually leads to a remarkable enhancement in the photocatalytic activity. All these unprecedented findings are expected to be crucial for understanding the roles of B and Ag dopants and their synergistic effect in numerous titania-mediated photocatalytic reactions. PMID:23316875

Feng, Ningdong; Wang, Qiang; Zheng, Anmin; Zhang, Zhengfeng; Fan, Jie; Liu, Shang-Bin; Amoureux, Jean-Paul; Deng, Feng

2013-01-22

315

Degradation of Glyphosate in Soil Photocatalyzed by Fe3O4/SiO2/TiO2 under Solar Light  

PubMed Central

In this study, Fe3O4/SiO2/TiO2 photocatalyst was prepared via a sol-gel method, and Fe3O4 particles were used as the core of the colloid. Diffraction peaks of Fe3O4 crystals are not found by XRD characterization, indicating that Fe3O4 particles are well encapsulated by SiO2. FTIR characterization shows that diffraction peaks of Ti-O-Si chemical bonds become obvious when the Fe3O4 loading is more than 0.5%. SEM characterization indicates that agglomeration occurs in the Fe3O4/SiO2/TiO2 photocatalyst, whereas photocatalysts modified by Fe3O4/SiO2 present excellent visible light absorption performance and photocatalytic activity, especially when the Fe3O4 loading is 0.5%. Photocatalytic degradation of glyphosate in soil by these photocatalysts under solar irradiation was investigated. Results show that 0.5% Fe3O4/SiO2/TiO2 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/cm2 or above 10 mW/cm2, but it is accelerated significantly when the sunlight intensity increases from 6 mW/cm2 to 10 mW/cm2.

Xu, Xuan; Ji, Fangying; Fan, Zihong; He, Li

2011-01-01

316

Study on the visible-light-induced photokilling effect of nitrogen-doped TiO2 nanoparticles on cancer cells  

PubMed Central

Nitrogen-doped TiO2 (N-TiO2) nanoparticles were prepared by calcining the anatase TiO2 nanoparticles under ammonia atmosphere. The N-TiO2 showed higher absorbance in the visible region than the pure TiO2. The cytotoxicity and visible-light-induced phototoxicity of the pure- and N-TiO2 were examined for three types of cancer cell lines. No significant cytotoxicity was detected. However, the visible-light-induced photokilling effects on cells were observed. The survival fraction of the cells decreased with the increased incubation concentration of the nanoparticles. The cancer cells incubated with N-TiO2 were killed more effectively than that with the pure TiO2. The reactive oxygen species was found to play an important role on the photokilling effect for cells. Furthermore, the intracellular distributions of N-TiO2 nanoparticles were examined by laser scanning confocal microscopy. The co-localization of N-TiO2 nanoparticles with nuclei or Golgi complexes was observed. The aberrant nuclear morphologies such as micronuclei were detected after the N-TiO2-treated cells were irradiated by the visible light.

2011-01-01

317

Study on the visible-light-induced photokilling effect of nitrogen-doped TiO2 nanoparticles on cancer cells  

NASA Astrophysics Data System (ADS)

Nitrogen-doped TiO2 (N-TiO2) nanoparticles were prepared by calcining the anatase TiO2 nanoparticles under ammonia atmosphere. The N-TiO2 showed higher absorbance in the visible region than the pure TiO2. The cytotoxicity and visible-light-induced phototoxicity of the pure- and N-TiO2 were examined for three types of cancer cell lines. No significant cytotoxicity was detected. However, the visible-light-induced photokilling effects on cells were observed. The survival fraction of the cells decreased with the increased incubation concentration of the nanoparticles. The cancer cells incubated with N-TiO2 were killed more effectively than that with the pure TiO2. The reactive oxygen species was found to play an important role on the photokilling effect for cells. Furthermore, the intracellular distributions of N-TiO2 nanoparticles were examined by laser scanning confocal microscopy. The co-localization of N-TiO2 nanoparticles with nuclei or Golgi complexes was observed. The aberrant nuclear morphologies such as micronuclei were detected after the N-TiO2-treated cells were irradiated by the visible light.

Li, Zheng; Mi, Lan; Wang, Pei-Nan; Chen, Ji-Yao

2011-04-01

318

Effects of Insulation Coating with Metal Salt on the Performance of Organic-Inorganic Hybrid Solar Cells  

Microsoft Academic Search

This work reports on the preparation of modified TiO2 electrodes, which could be applied to the photoanodes in a dye-sensitized solar cells (DSSCs). TiO2 layer was formed on a FTO (fluorine-doped tin oxide) coated glass via doctor-blade method and post heat treatment. Then, the various metal hydroxides and metal oxides were selectively deposited onto the TiO2 layers via electrophoretic deposition

Jong Tae Kim; Cham Kim; Hoyoung Kim; Sung Hwan Park; Kyoung-Cheon Son; Yoon Soo Han

2010-01-01

319

Adverse Effects of TiO2 Nanoparticles on Human Dermal Fibroblasts and How to Protect Cells  

NASA Astrophysics Data System (ADS)

We have studied the effects of exposure of human dermal fibroblasts to rutile and anatase TiO2 nanoparticles. We found that these particles can impair cell functions, with the latter being more potent at producing damage. We showed that the exposure to nanoparticles decreases cell area, cell proliferation, mobility, and ability to contract collagen. Individual particles are shown to penetrate easily through the cell membrane, in the absence of endocytosis, while some endocytosis is observed for larger particle clusters. Once inside, the particles are sequestered in vesicles, which continue to fill up with increasing incubation time till they rupture. We also tested particles that were coated with a dense grafted polymer brush and, using flow cytometry, showed that the coating prevented the particles from adhering to the cell membrane and hence penetrating the cell, which effectively decreases reactive oxygen species (ROS) formation and protects cells, even in the absence of light exposure. Considering the broad applications of these nanoparticles in personal health care products, the functionalized polymer coating can potentially play an important role in protecting cells and tissue from damage.

Pan, Zhi; Lee, Wilson; Slutsky, Lenny; Sandaresh, Sowmya; Elstein, Nicole; Clark, Richard; Pernodet, Nadine; Rafailovich, Miriam

2009-03-01

320

Solar light decomposition of DFP on the surface of anatase and rutile TiO2 prepared by hydrothermal treatment of microemulsions  

NASA Astrophysics Data System (ADS)

The photocatalytic decomposition of diisopropylfluorophosphate (DFP) over nanostructured anatase and rutile TiO2 powder was investigated by FTIR and XPS. Upon irradiation with artificial solar light DFP decomposed on both polymorphs as evidenced by FTIR. For both crystalline structures acetone and subsequently coordinated formate and carbonate were observed on the surface during the photocatalytic reaction as the isopropyl groups dissociated from DFP. XPS revealed that small amounts of phosphates and inorganic fluoride (TiF) gradually built up on both TiO2 surfaces, while organic F was present only on the rutile phase. From repeated cycles of intermittent DFP adsorption and irradiation measurements, the decomposition rates and formation of residuals on the surface were deduced. It was found that the overall oxidation yield is higher on anatase than rutile. The oxidation rate decreases with increasing irradiation time, an effect that is more pronounced on rutile. We find that both the difference between the polymorphs and the initial decrease of the oxidation yield can largely be explained by variations in surface area rather than poisoning by POx or F species. In particular, we observe a dramatic decrease of the specific area of rutile as a function of photocatalytic oxidation cycle.

Kiselev, A.; Andersson, M.; Mattson, A.; Shchukarev, A.; Sjöberg, S.; Palmqvist, A.; Österlund, L.

2005-06-01

321

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

322

Hydrothermal synthesis of ordered single-crystalline rutile TiO2 nanorod arrays on different substrates  

NASA Astrophysics Data System (ADS)

We report the mild hydrothermal synthesis of single-crystalline rutile TiO2 nanorod arrays (NRAs). The method reported here shows great versatility and can be used to grow TiO2 NRAs on a large diversity of substrates including Si, Si/SiO2, sapphire, Si pillars, and fluorine doped tin oxide (FTO)-covered glass. The average diameter and length of the nanorods prepared at typical conditions are ~60 nm and 400 nm, respectively. Dye-sensitized solar cells assembled with the TiO2 NRAs grown on the FTO-covered glass as photoanode were prepared with a photoconversion efficiency of ~1.10%.

Wang, Hong-En; Chen, Zhenhua; Leung, Yu Hang; Luan, Chunyan; Liu, Chaoping; Tang, Yongbing; Yan, Ce; Zhang, Wenjun; Zapien, Juan Antonio; Bello, Igor; Lee, Shuit-Tong

2010-06-01

323

Multi-scale dispersion in fuel cell anode catalysts: Role of TiO 2 towards achieving nanostructured materials  

Microsoft Academic Search

Multi-scale dispersion involving dispersion of catalyst particles on carbon support as well as intra-particle dispersion within the particles of a ternary Pt-Ru-Ti\\/C catalyst has been demonstrated. The presence of TiO2 can dramatically decreases the grain size of the obtained catalyst to about 1–2nm when compared with similarly prepared Pt-Ru\\/C (3–4nm) catalyst indicating that TiO2 can enhance the dispersion of the

Jiun-Ming Chen; Loka Subramanyam Sarma; Ching-Hsiang Chen; Ming-Yao Cheng; Shou-Chu Shih; Guo-Rung Wang; Din-Goa Liu; Jyh-Fu Lee; Mau-Tsu Tang; Bing-Joe Hwang

2006-01-01

324

Molecular damage in bi-isonicotinic acid adsorbed on rutile TiO 2(1 1 0)  

Microsoft Academic Search

Here we present the characteristic signatures in X-ray absorption and photoemission spectroscopy for molecular damage in adsorbed monolayers of bi-isonicotinic acid on a rutile TiO2(110) surface. Bi-isonicotinic acid is the anchor ligand through which many important inorganic complexes are bound to the surface of TiO2 in dye-sensitized solar cells. The nature of the damage caused by excessive heating of the

James N. O’Shea; J. Ben Taylor; Louise C. Mayor; Janine C. Swarbrick; Joachim Schnadt

2008-01-01

325

Photoacoustic and Photoelectrochemical Characterization of Inverse Opal TiO2 Sensitized with CdSe Quantum Dots  

Microsoft Academic Search

Inverse opal TiO2 may offer a novel and promising solution for enhancing the light harvesting efficiency of dye-sensitized solar cells (DSSCs). Its large interconnected pores enable a better penetration of the dye sensitizers via the matrix pores, making this material surpasses the efficiency of conventional TiO2 electrodes. Moreover, it also exhibits a photonic band gap that may enable a significant

Lina J. Diguna; Motonobu Murakami; Akira Sato; Yuki Kumagai; Taishi Ishihara; Naoki Kobayashi; Qing Shen; Taro Toyoda

2006-01-01

326

Photoacoustic and photoelectrochemical characterization of CdSe-sensitized TiO 2 electrodes composed of nanotubes and nanowires  

Microsoft Academic Search

Morphology of titanium dioxide (TiO2) electrodes and the choice of the sensitizers have been important factors for the improvement of dye-sensitized solar cell (DSSC) efficiency. TiO2 electrodes, having a higher degree of order than random fractal-like assemblies of nanoparticles, are desirable for the improvement of the electron transport characteristics. In recent years, semiconductor quantum dots (QDs) have attracted much attention

Qing Shen; Tadakazu Sato; Mituru Hashimoto; Changchuan Chen; Taro Toyoda

2006-01-01

327

Comparison of silatrane, phosphonic acid, and carboxylic acid functional groups for attachment of porphyrin sensitizers to TiO2 in photoelectrochemical cells.  

PubMed

A tetra-arylporphyrin dye was functionalized with three different anchoring groups used to attach molecules to metal oxide surfaces. The physical, photophysical and electrochemical properties of the derivatized porphyrins were studied, and the dyes were then linked to mesoporous TiO2. The anchoring groups were ?-vinyl groups bearing either a carboxylate, a phosphonate or a siloxy moiety. The siloxy linkages were made by treatment of the metal oxide with a silatrane derivative of the porphyrin. The surface binding and lability of the anchored molecules were studied, and dye performance was compared in a dye-sensitized solar cell (DSSC). Transient absorption spectroscopy was used to study charge recombination processes. At comparable surface concentration, the porphyrin showed comparable performance in the DSSC, regardless of the linker. However, the total surface coverage achievable with the carboxylate was about twice that obtainable with the other two linkers, and this led to higher current densities for the carboxylate DSSC. On the other hand, the carboxylate-linked dyes were readily leached from the metal oxide surface under alkaline conditions. The phosphonates were considerably less labile, and the siloxy-linked porphyrins were most resistant to leaching from the surface. The use of silatrane proved to be a practical and convenient way to introduce the siloxy linkages, which can confer greatly increased stability on dye-sensitized electrodes with photoelectrochemical performance comparable to that of the other linkers. PMID:23959453

Brennan, Bradley J; Llansola Portolés, Manuel J; Liddell, Paul A; Moore, Thomas A; Moore, Ana L; Gust, Devens

2013-08-20

328

Antibacterial properties and human gingival fibroblast cell compatibility of TiO2/Ag compound coatings and ZnO films on titanium-based material.  

PubMed

Titanium (Ti)-based materials are widely used in biomedical implant components and are applied successfully in various types of bone-anchored reconstructions. However, in dental implants the Ti materials contact not only bone but also gingival tissues, and are partially exposed to the oral cavity that includes bacteria. This study used titania and silver (TiO(2)/Ag) compound coatings and zinc oxide (ZnO) films to enhance the antibacterial activity of the Ti-based implant. The hydrophobicity of each sample was examined by measuring the contact angle. Streptococcus mutans and human gingival fibroblast (HGF) was cultured on the coated samples, and the antibacterial effects and cell compatibility were determined using a Syto9 fluorescence staining and MTT methods. For the TiO(2)/Ag samples, depositing Ag on the plate at a higher power (which increased the proportion of Ag) increased the contact angle and the hydrophobicity. The bacterial count was lowest for the 50 W TiO(2)/Ag sample, which contained 5.9% Ag. The contact angles of the ZnO samples did not show the same tendency. The antibacterial effect was higher on ZnO-coated samples since bacterial count was threefold lower on ZnO samples as compared to control samples (Ti plate). From the MTT assay test, the mean optical density values for TiO(2)/Ag-coated samples after 72 h of HGF adhesion were similar to the value obtained from the uncoated Ti. However, biocompatibility was lower on ZnO films than in control samples. Conclusively, the antibacterial activity was higher but the cell compatibility was lower on ZnO films than on TiO(2)/Ag coatings. PMID:21234622

Chang, Yin-Yu; Lai, Chih-Ho; Hsu, Jui-Ting; Tang, Chih-Hsin; Liao, Wan-Chuen; Huang, Heng-Li

2011-01-14

329

Preparation of Er 3+:YAlO 3\\/Fe-doped TiO 2–ZnO and its application in photocatalytic degradation of dyes under solar light irradiation  

Microsoft Academic Search

In this work, Er3+:YAlO3\\/Fe-doped TiO2–ZnO composite, a novel photocatalyst, was synthesized by ultrasonic dispersion and liquid boiling method and characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). Of which, as an upconversion luminescence agent, the Er3+:YAlO3 can transform the visible light in solar energy into ultraviolet light, satisfying the requirement of TiO2–ZnO composite for photocatalytic degradation. The photocatalytic

Jingqun Gao; Xiaoyu Luan; Jun Wang; Baoxin Wang; Kai Li; Ying Li; Pingli Kang; Guangxi Han

2011-01-01

330

Inx(OH)ySz as recombination barrier in TiO2/inorganic absorber heterojunctions  

NASA Astrophysics Data System (ADS)

In extremely thin absorber (ETA) solar cells a transparent mesoporous semiconductor is sensitized for visible light by depositing an inorganic absorber into the pores. One of the factors limiting the efficiency in such a device is the fast recombination of electrons injected from the excited absorber into the semiconductor, with holes in the absorber. The approach of this paper is to introduce indium (hydroxy) sulfide Inx(OH)ySz (band gap 2.5 eV) as a buffer layer at the TiO2/absorber interface to suppress recombination. Photoelectrical measurements on solid-state cells with a stack of flat TiO2, a wet-chemically applied Inx(OH)ySz layer and a sprayed CuInS2 absorber layer on top of it reveal a characteristic diode curve with an energy conversion efficiency of 2.1%, in contrast to the short circuiting observed for cells with TiO2/CuInS2 alone. Since Inx(OH)ySz forms a thin surface layer on TiO2-nanoparticles it is interesting for application in ETA solar cells. A TiO2/ETA electrode with quantum-sized PbS particles has been compared to a stacked TiO2/Inx(OH)ySz/ETA-configuration. Surface photovoltage spectrosocopy (SPS) measurements have shown that the electron recombination rate reduces if compared to TiO2/PbS without intermediate Inx(OH)ySz layer. The detailed Inx(OH)ySz functioning is not yet clarified.

Wienke, J.; Krunks, M.; Lenzmann, F.

2003-09-01

331

Catalytic activity of commercial of TiO 2 powders for the abatement of the bacteria ( E. coli) under solar simulated light: Influence of the isoelectric point  

Microsoft Academic Search

Thirteen different commercial TiO2 powders with specific surface areas varying from 9 to 335m2\\/g and with isoelectric points (IEP) from 3 to 7.5 were investigated for their catalytic activity in E. coli inactivation. The TiO2 samples zeta potential, attenuation sizes and isoelectric points (IEP) were measured by the electroacoustic method. The influence of the initial pH of the TiO2 suspension

D. Gumy; C. Morais; P. Bowen; C. Pulgarin; S. Giraldo; R. Hajdu; J. Kiwi

2006-01-01

332

Improved visible solar absorber based on TiO2 nanotube film by surface-loading of plasmonic Au nanoparticles  

NASA Astrophysics Data System (ADS)

Plasmon-driven electrons injection into active layers of optoelectronic devices is a promising and challenging research topic due to the great unavailability of suitable materials and devices configurations capable of providing comprehensively high photocurrent. In this letter, anodic TiO2 nanotubes array (TNA) films are formed to show enhanced visible light absorbing properties by surface-loading of isolated Au nanoparticles (NPs), exhibiting increased photocurrent and decreased response time. Surface Plasmon produces hot free electrons in the gold NPs when the device is illuminated by visible light with suitable photon energies, and the direct injection of hot electrons into TNA film is realized due to the energy nonequilibrium between gold NPs and TNA film. A significant fraction of these electrons will tunnel into the semiconductor's conduction band, which will introduce the surface n-type conduction layer, resulting in about 145% enhancement of photocurrent and 37% reduction of response time. A scattering-induced enhancement mechanism contributes effectively to the plasmonic photoresponse.

Shao, Zhufeng; Wang, Xinshun; Ren, Shoutian; Tian, Zhaoshuo; Fan, Shengli; Sun, Shengsheng; Liu, Shutian; Wang, Qiang

2013-08-01

333

TiO2 nanotubes as drug nanoreservoirs for the regulation of mobility and differentiation of mesenchymal stem cells.  

PubMed

The extracellular microenvironment plays a key role in the regulation of cellular behavior. To mimic the natural extracellular microenvironment, TiO(2) nanotube (TNT) arrays as drug nanoreservoirs for loading of bone morphogenetic protein 2 (BMP2) were constructed on titanium substrates and then covered with multilayered coatings of gelatin/chitosan (Gel/Chi) for controlled drug release. The multilayered coatings were constructed via a spin-assisted layer-by-layer assembly technique. The successful fabrication of this system was monitored by field emission scanning electron microscopy, atomic force microscopy, X-ray photoelectron spectroscopy and contact angle measurements. Multilayered coating with Gel/Chi retained the drug bioactivity and release properties, which were revealed by superoxide dismutase activity measurement. In addition, cytoskeleton observation and wound healing assay confirmed that BMP2-loaded and multilayer-coated TNT arrays were able to stimulate motogenic responses of mesenchymal stem cells (MSCs). More importantly, the system demonstrated that it was capable of promoting the osteoblastic differentiation of MSCs. This study may have potential impact on the development of bone implants for enhanced bone osseointegration. PMID:22040682

Hu, Yan; Cai, Kaiyong; Luo, Zhong; Xu, Dawei; Xie, Daichao; Huang, Yuran; Yang, Weihu; Liu, Peng

2011-10-20

334

Comparison of the killing effects between nitrogen-doped and pure TiO2 on HeLa cells with visible light irradiation  

PubMed Central

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.

2013-01-01

335

Investigation of the stability of solid-state dye-sensitized solar cells  

Microsoft Academic Search

The stability of the TiO2\\/ruthenium dye\\/CuI solid-state solar cell was investigated under continuous simulated sunlight illumination. The cells showed fast degradation under full-spectrum sunlight illumination, but showed rather good stability when the ultraviolet part of the illumination was removed. XPS measurements showed evidence that TiO2 could oxidize CuI in the presence of UV light. The photo-degradation mechanism of the cells

XIN-TONG ZHANG; TAKETO TAGUCHI; HAI-BIN WANG; QING-BO MENG; OSAMU SATO; AKIRA FUJISHIMA

2006-01-01

336

Electrical and electro-optical investigations of liquid crystal cells containing TiO2-V2O5 thin films prepared by sol-gel synthesis  

NASA Astrophysics Data System (ADS)

This work is aimed at a deeper understanding of the polarity-sensitive electro-optical response observed in a liquid crystal (LC) cell with asymmetric insertion of thin films of TiO2-V2O5 having a Ti/V atomic ratio of 1/1, prepared by sol-gel synthesis on a transparent indium tin oxide substrate. After preliminary structural characterization of the films, the electro-optical response of the liquid crystal cells containing a TiO2-V2O5 layer has been analyzed. The voltage thresholds of the Freedericksz transition are increased or decreased for anodic or the cathodic polarization, respectively, of the TiO2-V2O5 film. In such a way a polarity-sensitive electro-optical response is generated that has the same frequency as the field applied. Impedance and cyclic voltammetry measurements were performed on liquid crystal cells having TiO2-V2O5 films inserted as the electrode, for as-deposited films as well as for films annealed at 400 degC. The LC cell containing thermally annealed Ti/V 1/1 film showed a rectified square wave response instead of the usual impulsive one, quadratic versus electric field. On the contrary, the LC cell containing as-deposited Ti/V 1/1 film exhibits more complex electro-optical behavior with a weak asymmetric response. All the measurements suggest that charge redistribution of the ions, always present in the films, occurs during the intercalation-deintercalation processes induced by the voltage applied, and this is responsible for changes of the effective electric field that act on the liquid crystal layer.

Bruno, V.; Cazzanelli, E.; Scaramuzza, N.; Strangi, G.; Ceccato, R.; Carturan, G.

2002-11-01

337

TiO2-enriched polymeric powder coatings support human mesenchymal cell spreading and osteogenic differentiation  

Microsoft Academic Search

Novel polymeric powder coatings (PPC) were prepared by ultrafine powder coating technology and shown to support human mesenchymal cell attachment and growth. PPC surfaces enriched with nano-TiO2 (nTiO2) showed enhanced cellular responses, and were compared to commercially pure titanium (cpTi). After cell attachment and growth, osteogenic differentiation and bone matrix formation ensures osseointegration for implantable biomaterials. Therefore, the objective of

Mohammad Sayem Mozumder; Jesse Zhu; Hiran Perinpanayagam

2011-01-01

338

Molecular structure effect of pyridine-based surface ligand on the performance of P3HT:TiO? hybrid solar cell.  

PubMed

Colloid TiO(2) nanorods are used for solution-processable poly(3-hexyl thiophene): TiO(2) hybrid solar cell. The nanorods were covered by insulating ligand of oleic acid (OA) after sol-gel synthesis. Three more conducting pyridine type ligands: pyridine, 2,6-lutidine (Lut) and 4-tert-butylpyridine (tBP) were investigated respectively to replace OA. The power conversion efficiency (PCE) of the solar cell was increased because the electronic mobility of pyridine-type ligand-modified TiO(2) is higher than that of TiO(2)-OA. The enhancement of PCE is in the descending order of Lut > pyridine > tBP because of the effective replacement of OA by Lut. The PCE of solar cell can be further enhanced by ligand exchange of pyridine type ligand with conjugating molecule of 2-cyano-3-(5-(7-(thiophen-2-yl)-benzothiadiazol-4-yl) thiophen-2-yl) acrylic acid (W4) on TiO(2) nanorods because W4 has aligned bandgap with P3HT and TiO(2) to facilitate charge separation and transport. The electronic mobility of two-stage ligand exchanged TiO(2) is improved furthermore except Lut, because it adheres well and difficult to be replaced by W4. The amount of W4 on TiO(2)-tBP is 3 times more than that of TiO(2)-Lut (0.20 mol % vs. 0.06 mol %). Thus, the increased extent of PCE of solar cell is in the decreasing order of tBP > pyridine > Lut. The TiO(2)-tBP-W4 device has the best performance with 1.4 and 2.6 times more than TiO(2)-pyridine-W4 and TiO(2)-Lut-W4 devices, respectively. The pKa of the pyridine derivatives plays the major role to determine the ease of ligand exchange on TiO(2) which is the key factor mandating the PCE of P3HT:TiO(2) hybrid solar cell. The results of this study provide new insights of the significance of acid-base reaction on the TiO(2) surface for TiO(2)-based solar cells. The obtained knowledge can be extended to other hybrid solar cell systems. PMID:23323972

Lin, Jhih-Fong; Tu, Guang-Yao; Ho, Chun-Chih; Chang, Chun-Yu; Yen, Wei-Che; Hsu, Sheng-Hao; Chen, Yang-Fang; Su, Wei-Fang

2013-01-29

339

TiO2 -enriched polymeric powder coatings support human mesenchymal cell spreading and osteogenic differentiation.  

PubMed

Novel polymeric powder coatings (PPC) were prepared by ultrafine powder coating technology and shown to support human mesenchymal cell attachment and growth. PPC surfaces enriched with nano-TiO(2) (nTiO(2)) showed enhanced cellular responses, and were compared to commercially pure titanium (cpTi). After cell attachment and growth, osteogenic differentiation and bone matrix formation ensures osseointegration for implantable biomaterials. Therefore, the objective of this study was to determine if mesenchymal cells grown on PPC could undergo osteogenic differentiation by inducing Runx2 and bone matrix proteins, and then initiate mineralization. Atomic force microscopy revealed intricate three-dimensional micro-topographies, and the measures of nano-roughness and porosity were similar for all PPC surfaces. Scanning electron microscopy showed that the cells attached and spread out over all of the surfaces. After 1 week in osteogenic media, RT-PCR analysis showed the induction of Runx2, the up-regulation of type I collagen, and the initial detection of alkaline phosphatase and bone sialoprotein. After 4 weeks, Alizarin Red staining showed mineral deposition. However, cell spreading and osteogenic differentiation were significantly (P < 0.05) higher on the cpTi controls than on the PPC surfaces. Furthermore, spreading and differentiation were consistently higher on the titanium-enriched PPC-2, -3 and -4 than on the titanium-free PPC-1. Therefore, despite the presence of complex micro-topographies and nano-features, titanium-enrichment enhanced the cellular response, and pure titanium still provided the best substrate. These findings confirm the cytocompatibility of these novel polymeric coatings and suggest that titanium-enrichment and nTiO(2) additives may enhance their performance. PMID:21555842

Mozumder, Mohammad Sayem; Zhu, Jesse; Perinpanayagam, Hiran

2011-05-10

340

TiO2 nanotube stimulate chondrogenic differentiation of limb mesenchymal cells by modulating focal activity  

PubMed Central

Vertically aligned, laterally spaced nanoscale titanium nanotubes were grown on a titanium surface by anodization, and the growth of chondroprogenitors on the resulting surfaces was investigated. Surfaces bearing nanotubes of 70 to 100 nm in diameter were found to trigger the morphological transition to a cortical actin pattern and rounded cell shape (both indicative of chondrocytic differentiation), as well as the up-regulation of type II collagen and integrin ?4 protein expression through the down-regulation of Erk activity. Inhibition of Erk signaling reduced stress fiber formation and induced the transition to the cortical actin pattern in cells cultured on 30-nm-diameter nanotubes, which maintained their fibroblastoid morphologies in the absence of Erk inhibition. Collectively, these results indicate that a titanium-based nanotube surface can support chondrocytic functions among chondroprogenitors, and may therefore be useful for future cartilaginous applications.

Kim, Dongkyun; Choi, Bohm; Song, Jinsoo; Kim, Sunhyo; Oh, Seunghan; Jin, Eun-Heui; Kang, Shin-Sung

2011-01-01

341

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

342

Synthesis of TiO2 hollow nanofibers by co-axial electrospinning and its superior lithium storage capability in full-cell assembly with olivine phosphate  

NASA Astrophysics Data System (ADS)

We report the formation and extraordinary Li-storage properties of TiO2 hollow nanofibers by co-axial electrospinning in both the half-cell and full-cell configurations. Li-insertion properties are first evaluated as anodes in the half-cell configuration (Li/TiO2 hollow nanofibers) and we found that reversible insertion of ~0.45 moles is feasible at a current density of 100 mA g-1. The half-cell displayed a good cyclability and retained 84% of its initial reversible capacity after 300 galvanostatic cycles. The full-cell is fabricated with a commercially available olivine phase LiFePO4 cathode under optimized mass loading. The LiFePO4/TiO2 hollow nanofiber cell delivered a reversible capacity of 103 mA h g-1 at a current density of 100 mA g-1 with an operating potential of ~1.4 V. Excellent cyclability is noted for the full-cell configuration, irrespective of the applied current densities, and it retained 88% of reversible capacity after 300 cycles in ambient conditions at a current density of 100 mA g-1.We report the formation and extraordinary Li-storage properties of TiO2 hollow nanofibers by co-axial electrospinning in both the half-cell and full-cell configurations. Li-insertion properties are first evaluated as anodes in the half-cell configuration (Li/TiO2 hollow nanofibers) and we found that reversible insertion of ~0.45 moles is feasible at a current density of 100 mA g-1. The half-cell displayed a good cyclability and retained 84% of its initial reversible capacity after 300 galvanostatic cycles. The full-cell is fabricated with a commercially available olivine phase LiFePO4 cathode under optimized mass loading. The LiFePO4/TiO2 hollow nanofiber cell delivered a reversible capacity of 103 mA h g-1 at a current density of 100 mA g-1 with an operating potential of ~1.4 V. Excellent cyclability is noted for the full-cell configuration, irrespective of the applied current densities, and it retained 88% of reversible capacity after 300 cycles in ambient conditions at a current density of 100 mA g-1. Electronic supplementary information (ESI) available. See DOI: 10.1039/c3nr01128c

Zhang, X.; Aravindan, V.; Kumar, P. Suresh; Liu, H.; Sundaramurthy, J.; Ramakrishna, S.; Madhavi, S.

2013-06-01

343

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

344

Water adsorption on rutile TiO2(110) for applications in solar hydrogen production: A systematic hybrid-exchange density functional study  

NASA Astrophysics Data System (ADS)

Periodic hybrid-exchange density functional theory calculations are used to predict the structure of water on the rutile TiO2(110) surface (?? 1 ML), which is an important first step towards understanding the photocatalytic processes that occur in solar water splitting. A detailed model describing the water-water and water-surface interactions is developed by exploring thoroughly the adsorption energetics. The possible adsorption mode—molecular, dissociative, or mixed—and the binding energy are studied as a function of coverage and arrangement, thus separation, of adsorbed species. These dependencies (coverage and arrangement) have a significant influence on the nature of the interactions involved in the H2O-TiO2 system. The importance of both direct intermolecular and surface-mediated interactions between surface species is emphasized. Finally, to gain insight into the photooxidation of adsorbed species at the surface, the electronic structure of the predicted adsorbate-substrate geometries is analyzed in terms of total and projected density of states.

Patel, M.; Mallia, G.; Liborio, L.; Harrison, N. M.

2012-07-01

345

Supported noble metals on hydrogen-treated TiO2 nanotube arrays as highly ordered electrodes for fuel cells.  

PubMed

Hydrogen-treated TiO2 nanotube (H-TNT) arrays serve as highly ordered nanostructured electrode supports, which are able to significantly improve the electrochemical performance and durability of fuel cells. The electrical conductivity of H-TNTs increases by approximately one order of magnitude in comparison to air-treated TNTs. The increase in the number of oxygen vacancies and hydroxyl groups on the H-TNTs help to anchor a greater number of Pt atoms during Pt electrodeposition. The H-TNTs are pretreated by using a successive ion adsorption and reaction (SIAR) method that enhances the loading and dispersion of Pt catalysts when electrodeposited. In the SIAR method a Pd activator can be used to provide uniform nucleation sites for Pt and leads to increased Pt loading on the H-TNTs. Furthermore, fabricated Pt nanoparticles with a diameter of 3.4 nm are located uniformly around the pretreated H-TNT support. The as-prepared and highly ordered electrodes exhibit excellent stability during accelerated durability tests, particularly for the H-TNT-loaded Pt catalysts that have been annealed in ultrahigh purity H2 for a second time. There is minimal decrease in the electrochemical surface area of the as-prepared electrode after 1000 cycles compared to a 68 % decrease for the commercial JM 20 % Pt/C electrode after 800 cycles. X-ray photoelectron spectroscopy shows that after the H-TNT-loaded Pt catalysts are annealed in H2 for the second time, the strong metal-support interaction between the H-TNTs and the Pt catalysts enhances the electrochemical stability of the electrodes. Fuel-cell testing shows that the power density reaches a maximum of 500 mWcm(-2) when this highly ordered electrode is used as the anode. When used as the cathode in a fuel cell with extra-low Pt loading, the new electrode generates a specific power density of 2.68 kWg(Pt) (-1) . It is indicated that H-TNT arrays, which have highly ordered nanostructures, could be used as ordered electrode supports. PMID:23450835

Zhang, Changkun; Yu, Hongmei; Li, Yongkun; Gao, Yuan; Zhao, Yun; Song, Wei; Shao, Zhigang; Yi, Baolian

2013-02-28

346

Effect of coadsorbent on the photovoltaic performance of zinc pthalocyanine-sensitized solar cells.  

PubMed

The effect of chenodeoxycholic acid as a coadsorbent on TiO 2 nanocrystalline solar cells incorporating phthalocyanine sensitizers was studied under various conditions. Adding chenodeoxycholic acid onto TiO 2 nanoparticles not only reduces the adsorption of phthalocyanine sensitizers but also prevents sensitizer aggregation, leading to different photovoltaic performance. The inspection of IPCE and absorption spectra showed that the load of phthalocyanine sensitizers is strongly dependent on the molar concentration of chenodeoxycholic acid coadsorbent. The open circuit voltage of the solar cells with chenodeoxycholic acid coadsorbent increases due to the enhanced electron lifetime in TiO 2 nanoparticles coupled with the band edge shift of TiO 2 to negative potentials. PMID:18435553

Yum, Jun-Ho; Jang, Song-Rim; Humphry-Baker, Robin; Grätzel, M; Cid, Juan-José; Torres, Tomas; Nazeeruddin, Md K

2008-04-25

347

Effect of coadsorbent on the photovoltaic performance of squaraine sensitized nanocrystalline solar cells.  

PubMed

The effect of chenodeoxycholic acid as the coadsorbent with a squaraine sensitizer on TiO(2) nanocrystalline solar cells was investigated, and it was found that the coadsorbent prevents the squaraine sensitizer from aggregating on the TiO(2) nanoparticles but reduces dye loading leading to an interdependent photovoltaic performance. Analysis of the absorption spectra, and incident monochromatic photon-to-current conversion efficiency data showed that the load of squaraine sensitizer as well as the appearance of H-aggregates is strongly dependent on the molar concentration of chenodeoxycholic acid coadsorbent. The open circuit voltage of the solar cells with chenodeoxycholic acid increases due to the enhanced electron lifetime in the TiO(2) nanoparticles coupled with the band edge shift of TiO(2) to negative potentials. PMID:21832665

Yum, J H; Moon, S J; Humphry-Baker, R; Walter, P; Geiger, T; Nüesch, F; Grätzel, M; Nazeeruddin, M D K

2008-09-25

348

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

349

Solar cells  

Microsoft Academic Search

Solar cells are based on the photovoltaic effect of converting solar energy into electric energy. The mechanism for solar cells is divided into steps, that is, electron-hole pair generation by absorption of light in semiconductors, separation of electron-hole pairs by built-in potential, electron-hole recombination, collection of charge carriers by metal electrodes, etc. In this article, the principle and the theories

Hiroshi Tsubomura; Hikaru Kobayashi

1993-01-01

350

Photocatalytic deactivation of airborne microbial cells by the stainless steel sieves with surface coated TiO 2 thin films  

Microsoft Academic Search

Stainless steel (SS) 304 sieves are characterized by their high permeability and high surface area, which can be flexibly used in different photochemical reactor designs. In this work, low pressure plasma cleaning methods in Ar or N2 atmospheres were adopted to clean the surfaces of sieves prior to the deposition of TiO2 coatings by sol–gel and dipping methods. Heat treating

Yu-Jie Chang; Jyh-Wei Lee; Ching-Hsing Lin; Chen-Yu Chang; Yao-Chuan Lee; Mei-Yin Hwa

2010-01-01

351

MTA-enriched nanocomposite TiO2-polymeric powder coatings support human mesenchymal cell attachment and growth  

Microsoft Academic Search

The objective of the study described in this paper was the development of novel polymer\\/ceramic nanocomposite coatings for implants through the application of ultrafine powder coating technology. Polyester resins were combined with µm-sized TiO2 (25%) as the biocompatibility agent, nTiO2 (0.5%) as the flow additive and mineral trioxide aggregates (ProRoot® MTA, 5%) as bioactive ceramics. Ultrafine powders were prepared and

Wen Shi; Mohammad Sayem Mozumder; Hui Zhang; Jesse Zhu; Hiran Perinpanayagam

2012-01-01

352

TiO2 thin films prepared by sol - gel method  

NASA Astrophysics Data System (ADS)

There is a growing awareness that titania (TiO2) and TiO2-based oxide systems are the most promising candidates for the development of photoelectrodes for photoelectrochemical cell (PEC) for solar-hydrogen production [1]. The PEC is equipped with a single photoelectrode (photoanode) and cathode, both of which are immersed in an aqueous electrolyte. In this work we present a sol-gel method to prepare TiO2 thin films on ITO using tetraisopropoxides of titanium, acetylacetone, 1-butanol and Tween 80 as surfactant. The films were deposited on ITO coated glass slides by spray pyrolysis. UV-VIS spectra and fluorescence measurements were made for the solutions and films. X-ray diffraction was used for structural investigations and the morphology of the film was studied by Scanning Electron Microscopy.

Suciu, R. C.; Indrea, E.; Silipas, T. D.; Dreve, S.; Rosu, M. C.; Popescu, V.; Popescu, G.; Nascu, H. I.

2009-08-01

353

Free-standing arrays of isolated TiO2 nanotubes through supercritical fluid drying.  

PubMed

A common complication in fabricating arrays of TiO(2) nanotubes is that they agglomerate into tightly packed bundles during the inevitable solvent evaporation step. This problem is particularly acute for template-fabricated TiO(2) nanotubes, as the geometric tunability of this technique enables relatively large inter-pore spacings or, from another perspective, more space for lateral displacement. Our work showed that agglomeration results from the surface tension forces that are present as the ambient solvent is evaporated from the nanotube film. Herein, we report a processing and fabrication approach that utilizes supercritical fluid drying (CO(2)) to prepare arrays of template-fabricated TiO(2) nanotubes that are free-standing and spatially isolated. This approach could be beneficial to many emerging technologies, such as solid-state dye-sensitized solar cells and vertically-oriented carbon nanotube electrodes. PMID:22147515

Deneault, James R; Xiao, Xiaoyin; Kang, Tae-Sik; Wang, Joanna S; Wai, Chien M; Brown, Gail J; Durstock, Michael F

2011-12-06

354

Quantum junction solar cells.  

PubMed

Colloidal quantum dot solids combine convenient solution-processing with quantum size effect tuning, offering avenues to high-efficiency multijunction cells based on a single materials synthesis and processing platform. The highest-performing colloidal quantum dot rectifying devices reported to date have relied on a junction between a quantum-tuned absorber and a bulk material (e.g., TiO(2)); however, quantum tuning of the absorber then requires complete redesign of the bulk acceptor, compromising the benefits of facile quantum tuning. Here we report rectifying junctions constructed entirely using inherently band-aligned quantum-tuned materials. Realizing these quantum junction diodes relied upon the creation of an n-type quantum dot solid having a clean bandgap. We combine stable, chemically compatible, high-performance n-type and p-type materials to create the first quantum junction solar cells. We present a family of photovoltaic devices having widely tuned bandgaps of 0.6-1.6 eV that excel where conventional quantum-to-bulk devices fail to perform. Devices having optimal single-junction bandgaps exhibit certified AM1.5 solar power conversion efficiencies of 5.4%. Control over doping in quantum solids, and the successful integration of these materials to form stable quantum junctions, offers a powerful new degree of freedom to colloidal quantum dot optoelectronics. PMID:22881834

Tang, Jiang; Liu, Huan; Zhitomirsky, David; Hoogland, Sjoerd; Wang, Xihua; Furukawa, Melissa; Levina, Larissa; Sargent, Edward H

2012-08-16

355

Time-dependent density functional theory study of squaraine dye-sensitized solar cells  

Microsoft Academic Search

We employ time-dependent density functional theory to study the optical properties of a squaraine sensitized TiO2 system, as a model for the corresponding dye-sensitized solar cell. The all-organic squaraine dye is particularly promising for light absorption in the red spectral region. We compute the photoabsorption spectrum of a periodic TiO2 slab exposing anatase (101) surfaces, both for the clean slab

Dario Rocca; Ralph Gebauer; Filippo De Angelis; Mohammad K. Nazeeruddin; Stefano Baroni

2009-01-01

356

Effect of coadsorbent on the photovoltaic performance of squaraine sensitized nanocrystalline solar cells  

Microsoft Academic Search

The effect of chenodeoxycholic acid as the coadsorbent with a squaraine sensitizer on TiO2 nanocrystalline solar cells was investigated, and it was found that the coadsorbent prevents the squaraine sensitizer from aggregating on the TiO2 nanoparticles but reduces dye loading leading to an interdependent photovoltaic performance. Analysis of the absorption spectra, and incident monochromatic photon-to-current conversion efficiency data showed that

J. H. Yum; S. J. Moon; R. Humphry-Baker; P. Walter; T. Geiger; F. Nüesch; M. Grätzel; M. d. K. Nazeeruddin

2008-01-01

357

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

358

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

359

Synthesis of hierarchical TiO2 nanowires with densely-packed and omnidirectional branches.  

PubMed

In this study, a hierarchical TiO2 nanostructure with densely-packed and omnidirectional branches grown by a hydrothermal method is introduced. This morphology is achieved via high-concentration TiCl4 treatment of upright backbone nanowires (NWs) followed by hydrothermal growth. Secondary nanobranches grow in all directions from densely distributed, needle-like seeds on the jagged round surface of the backbone NWs. In addition, hierarchical, flower-like branches grow on the top surface of each NW, greatly increasing the surface area. For dye-sensitized solar cell (DSSC) applications, the TiO2 nanostructure demonstrated a photoconversion efficiency of up to 6.2%. A parametric study of the DSSC efficiency showed that branched TiO2 DSSCs can achieve nearly four times the efficiency of non-branched TiO2 nanowire DSSCs, and up to 170% the efficiency of previously-reported sparsely-branched TiO2 NW DSSCs. PMID:24071926

Lee, Daeho; Rho, Yoonsoo; Allen, Frances I; Minor, Andrew M; Ko, Seung Hwan; Grigoropoulos, Costas P

2013-09-27

360

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

2010-03-10

361

Chemical reactions on rutile TiO2(110).  

PubMed

Understanding the surface chemistry of TiO2 is key to the development and optimisation of many technologies, such as solar power, catalysis, gas sensing, medical implantation, and corrosion protection. In order to address this, considerable research effort has been directed at model single crystal surfaces of TiO2. Particular attention has been given to the rutile TiO2(110) surface because it is the most stable face of TiO2. In this critical review, we discuss the chemical reactivity of TiO2(110), focusing in detail on four molecules/classes of molecules. The selected molecules are water, oxygen, carboxylic acids, and alcohols-all of which have importance not only to industry but also in nature (173 references). PMID:18818830

Lun Pang, Chi; Lindsay, Robert; Thornton, Geoff

2008-09-04

362

Multi-walled carbon nanotubes modified by sulfated TiO 2 – A promising support for Pt catalyst in a direct ethanol fuel cell  

Microsoft Academic Search

We report the synthesis of multi-walled carbon nanotubes coated with sulfated TiO2 (S–TiO2\\/MWCNTs) as a promising support for Pt catalyst in a direct ethanol fuel cell. Highly dispersed Pt nanoparticles were supported on the S–TiO2\\/MWCNT composites by NaBH4 reduction procedure (Pt–S–TiO2\\/MWCNTs). The presence and nature of the catalyst were characterized by Fourier transform infrared spectroscopy, X-ray diffraction, high-resolution transmission electron

Dao-Jun Guo; Xin-Ping Qiu; Li-Quan Chen; Wen-Tao Zhu

2009-01-01

363

Weavable dye sensitized solar cells exploiting carbon nanotube yarns  

NASA Astrophysics Data System (ADS)

Weavable Dye Sensitized Solar Cells (DSSC) made with flexible yarns of conductive multiwalled carbon nanotubes (MWNTs) were produced having a power conversion efficiency above 3%. This was achieved with a specific design and careful consideration of the yarn function in the DSSC. Fermat yarns of MWNTs individually coated with mesoporous TiO2 layer were twisted together and coated with more mesoporous TiO2 to create a 3 dimensional photo electrode to overcome electron diffusion length issues. Archimedian yarns of MWNTs coated with a thin layer of platinum worked as a counter electrode to complete the architecture used in this DSSC.

Velten, Josef; Kuanyshbekova, Zharkynay; Göktepe, Özer; Göktepe, Fatma; Zakhidov, Anvar

2013-05-01

364

Solar hydrogen production by tandem cell system composed of metal oxide semiconductor film photoelectrode and dye-sensitized solar cell  

NASA Astrophysics Data System (ADS)

Photocatalytic and photoelectrochemical approaches to solar hydrogen production in our group were introduced. In photocatalytic water splitting system using NiOx/ TiO2 powder photocatalyst with concentrated Na2CO3 aqueous solution, solar energy conversion efficiency to H2 and O2 production (STH efficiency) was 0.016%. In addition, STH efficiency of visible light responding photocatalyst, NiOx/ promoted In0.9Ni0.1TaO4, was estimated at 0.03%. In photoelectrochemical system using an oxide semiconductor film phptoelectrode, STH efficiencies of meosporous TiO2 (Anatase) , mesoporous visible light responding S-doped TiO2 (Anatase) and WO3 film were 0.32-0.44% at applied potential of 0.35 V vs NHE, 0.14% at 0.55 V and 0.44% at 0.9 V, respectively. Finally, solar hydrogen production by tandem cell system composed of an oxide semiconductor photoelectrode, a Pt wire counter electrode and a dye-sensitized solar cell (DSC) was investigated. As photoelectrodes, meosporous TiO2 (Anatase), mesoporous S-doped TiO2 (Anatase), WO3, BiVO4 and Fe2O3 film were tested. STH efficiency of tandem cell system composed of a WO3 film photoelectrode, and a two-series-connected DSC (Voc = 1.4 V) was 2.5-2.8%. In conclusion, it is speculated that more than 5% STH efficiency will be obtained by tandem cell system composed of an oxide semiconductor photoelectrode and a two-series-connected DSC in near future. This suggests a cost-effective and practical application of this system for solar hydrogen production.

Arakawa, H.; Shiraishi, C.; Tatemoto, M.; Kishida, H.; Usui, D.; Suma, A.; Takamisawa, A.; Yamaguchi, T.

2007-10-01

365

Multichromophore light harvesting in hybrid solar cells.  

PubMed

A new technologically relevant method for multichromophore sensitizing of hybrid blend solar cells is presented. Two dyes having complementary absorption in the UV-visible regions are individually adsorbed on nanocrystalline TiO(2) powder. These dyed TiO(2) nanoparticles are blended with an organic hole-conductor (HC) Spiro-OMeTAD in desired compositions and applied on a conducting substrate by doctor-blading at room temperature to fabricate multichromophore-sensitized hybrid blend solar cells. The external quantum efficiency (EQE) of the single hybrid layer system fabricated with two dyes, that absorb mainly UV (TPD dye) and visible regions (Ru-TPA-NCS dye), exhibited a clear panchromatic response with the sum of the EQE characteristics of each single dye cell. The first results of a multichromophore-sensitized solid-state solar cell showed J(sc) of 2.1 mA cm(-2), V(oc) of 645 mV, FF of 47% and efficiency of 0.65% at AM 1.5 G, 100 mW cm(-2) illumination intensity. The J(sc) of the multichromophore cell is the sum of the individually dyed solar cells. The process described here is technically very innovative and very simple in procedure. It has potentials to be adopted for panchromatic sensitization using more than two dyes in a single hybrid layer or layer-wise fabrication of a tandem structure at room temperature. PMID:21695348

Bandara, Jayasundera; Willinger, Katja; Thelakkat, Mukundan

2011-06-22

366

Atmospheric Pressure Chemical Vapor Deposition of High Silica SiO2-TiO2 Antireflective Thin Films for Glass Based Solar Panels  

SciTech Connect

The atmospheric pressure chemical vapor deposition (APCVD) of SiO2-TiO2 thin films employing [[(tBuO)3Si]2O-Ti(OiPr)2], which can be prepared from commercially available materials, results in antireflective thin films on float glass under industrially relevant manufacturing conditions. It was found that while the deposition temperature had an effect on the SiO2:TiO2 ratio, the thickness was dependent on the time of deposition. This study shows that it is possible to use APCVD employing a single source precursor containing titanium and silicon to produce thin films on float glass with high SiO2:TiO2 ratios.

Klobukowski, Erik R [ORNL; Tenhaeff, Wyatt E [ORNL; McCamy, James [PPG; Harris, Caroline [PPG; Narula, Chaitanya Kumar [ORNL

2013-01-01

367

Influence of the sensitizer adsorption mode on the open-circuit potential of dye-sensitized solar cells.  

PubMed

We report a combined experimental and theoretical study on the origin of the different open circuit potentials observed in dye-sensitized solar cells using Ru(II)-polypyridyl homoleptic and heteroleptic sensitizers. We have measured the photovoltaic data of different sensitizers and used DFT calculations to analyze the electronic structure of dye-sensitized TiO(2) nanoparticles. Heteroleptic sensitizers adsorb onto TiO(2) via a single bipyridine, leading to a TiO(2) conduction band downshift and overall reduction of the cell open circuit potential. PMID:17854229

De Angelis, Filippo; Fantacci, Simona; Selloni, Annabella; Grätzel, Michael; Nazeeruddin, Mohammed K

2007-09-14

368

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

2011-06-28

369

TiO2 Nanotubes arrays sensitized with Bi2MoO6 NPs and QDs (PbS, CdS) for solar energy harvesting  

Microsoft Academic Search

We report investigation results of photocatalytic properties of TiO2 nanotube arrays sensitized with Bi2MoO6 metal oxides and PbS, CdS quantum dots (QDs) to address the issues of improving the efficiency of water-splitting under visible-light irradiation for hydrogen energy. XRD and TEM investigations showed well crystallized Bi2MoO6 nanoparticles on the TiO2 nanotube wall. Measurements of photo conversion efficiency and monochromatic absorption

U. Shaislamov; B. Yang

2011-01-01

370

Synthesis and Characterization of Filtered-cathodic-vacuum-arc-deposited TiO2 Films for Photovoltaic Applications  

NASA Astrophysics Data System (ADS)

Titanium dioxide (TiO2) is well-known as a photovoltaic and photocatalytic material. For improvement in the dye-sensitized solar cell (DSSC) performance efficiency, the photocatalyst TiO2 layer would be desired in nanoporous anatase. In this research, TiO2 films were synthesized on glass or p-type silicon substrate using our in-house Filtered Cathodic Vacuum Arc Deposition (FCVAD) system. The deposition was operated at varied oxygen (O2) partial pressures of 10-4, 10-3, 10-2 to 10-1 torr with fixed 0 or 250-V bias and 600-V arc for 10 or 20 minutes. The film transparency increased with increasing of the O2 pressure, indicating increase in the structure required for applications in dye-sensitized solar cells. The films were characterized using the Energy-Dispersive X-ray spectroscopy (EDS) and Raman spectroscopy techniques. The EDS confirmed that the transparent deposited films contained stoichiometric titanium and oxygen under the medium O2 pressure. Raman spectra confirmed that the films were TiO2 containing some rutile but no anatase which needed annealing to form. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) were used for evaluation of the film's surface morphology and thickness. The result showed that increasing of the O2 pressure decreased the thickness to a nanoscale but increased the amount of TiO2.

Aramwit, C.; Intarasiri, S.; Bootkul, D.; Tippawan, U.; Supsermpol, B.; Seanphinit, N.; Ruangkul, W.; Yu, L. D.

2013-04-01

371

Dye-sensitized solar tubes: A new solar cell design for efficient current collection and improved cell sealing  

Microsoft Academic Search

A dye-sensitized solar cell (DSSC) fabricated inside a glass tube to form a dye-sensitized solar tube (DSST) is presented. We developed the synthesis of Fluorine-doped Tin oxide (FTO) with a high optical transmittance and low sheet resistance, which was deposited inside a glass tube by spray pyrolysis. The FTO was covered with a mesoporous TiO2 film using electrophoretic deposition (EPD).

Zion Tachan; Sven Rühle; Arie Zaban

2010-01-01

372

Preparation and Performance of Ordered Porous TiO2 Film Doped with Gd3+  

NASA Astrophysics Data System (ADS)

An organic template of polystyrene colloidal crystals was fabricated through dip-coating in a polystyrene emulsion. Based on the template, an ordered porous TiO2 film doped with Gd3+ was deposited on a conductive glass. x-ray diffractometry (XRD), scanning electron microscopy (SEM), UV-vis spectroscopy were used to characterize the structures and properties of the film. The as-produced film was used as an electrode in dye-sensitized solar cells with a sandwich structure. XRD showed that anatase TiO2 was obtained. SEM images clearly demonstrated that these films had an ordered porous structure, mainly in a hexagonal orientation. UV-vis spectroscopy revealed that the absorption was improved in both the ultraviolet and the visible areas. Under simulated solar illumination, a short circuit current of 0.618 mA and an open circuit voltage of 0.538 V were attained, which were better than the performances of only a TiO2 film electrode and an ordered porous TiO2 film electrode.

Zhou, Yi; Li, Hong; Shi, Dehui; Lv, Caixia; Dang, Mingming; Lou, Wen

2010-11-01

373

Preparation and Performance of Ordered Porous TiO2 Film Doped with Gd3+  

NASA Astrophysics Data System (ADS)

An organic template of polystyrene colloidal crystals was fabricated through dip-coating in a polystyrene emulsion. Based on the template, an ordered porous TiO2 film doped with Gd3+ was deposited on a conductive glass. x-ray diffractometry (XRD), scanning electron microscopy (SEM), UV-vis spectroscopy were used to characterize the structures and properties of the film. The as-produced film was used as an electrode in dye-sensitized solar cells with a sandwich structure. XRD showed that anatase TiO2 was obtained. SEM images clearly demonstrated that these films had an ordered porous structure, mainly in a hexagonal orientation. UV-vis spectroscopy revealed that the absorption was improved in both the ultraviolet and the visible areas. Under simulated solar illumination, a short circuit current of 0.618 mA and an open circuit voltage of 0.538 V were attained, which were better than the performances of only a TiO2 film electrode and an ordered porous TiO2 film electrode.

Zhou, Yi; Li, Hong; Shi, Dehui; Lv, Caixia; Dang, Mingming; Lou, Wen

2011-10-01

374

Preparation of anatase/rutile mixed-phase titania nanoparticles for dye-sensitized solar cells.  

PubMed

Acid-labile high surface mesoporous ZnO/Zn(OH)2 composite material is used as a novel hard template for the preparation of mesoporous amorphous TiO2. The template-free amorphous TiO2 material is then thermally crystallized at suitable temperature to control the relative ratio of anatase and rutile phases in a particle. Four different anatase/rutile (AR) mixed-phase TiO2 nanoparticles (AR-3, AR-15, AR-20, and AR-23 denoted for the samples of 3%, 15%, 20%, and 23% rutile phase, respectively) are prepared and characterized by powder X-ray diffraction (PXRD) and transmission electron microscopy (TEM). The coexistence of anatase and rutile phases in a TiO2 nanoparticle is visually confirmed by HRTEM analysis. These mixed-phase TiO2 nanoparticles are examined as candidates for photoelectrodes of dye-sensitized solar cells (DSSCs). The J-V curves and IPCE spectra for the DSSCs prepared from the mixed-phase TiO2 nanoparticles are obtained, and their photovoltaic properties are investigated. The photo-conversion efficiency (eta) indicates the highest value of 5.07% for AR-20. The synergistic effect of coexisting anatase and rutile phases with an optimal ratio in a TiO2 nanoparticle of AR-20 for an efficient interfacial transfer of photo-generated electrons is likely to lead to the highest efficiency among the AR-n samples. PMID:23755675

Hwang, Yong-Kyung; Park, Sung Soo; Lim, Jun-Heok; Won, Yong Sun; Huh, Seong

2013-03-01

375

Enhanced photoelectric conversion efficiency of dye-sensitized solar cells by the incorporation of dual-mode luminescent NaYF4:Yb3+/Er3+.  

PubMed

This work focuses on the design of composite photoanodes with dual-mode luminescent function as well as the effects of luminescent phosphors on the photoelectric properties of dye-sensitized solar cells. Specifically, hexagonal phase NaYF4:Yb(3+)/Er(3+) microcrystals were prepared by a hydrothermal method and added to the TiO2 photoanodes of dye-sensitized solar cells. The results indicated that the TiO2-NaYF4:Yb(3+)/Er(3+) composite photoanodes can emit visible light under 495 or 980 nm excitation, and then the visible light can be absorbed by dye N719 to improve light harvesting and thereby the efficiency of the solar cell. Under simulated solar radiation in the wavelength range of ?? 400 nm, the photoelectric conversion efficiency of TiO2-NaYF4:Yb(3+)/Er(3+) cell was increased by 10% compared to pure TiO2 cell. For the electrodes with the same thickness, the amount of dye adsorption of the photoanodes decreased a little after adding NaYF4:Yb(3+)/Er(3+), which was attributed to the decrease of TiO2 in the photoanodes. The electron transport and interfacial recombination kinetics were investigated by the electrochemical impedance spectroscopy and intensity-modulated photocurrent/photovoltage spectroscopy. The TiO2-NaYF4:Yb(3+)/Er(3+) cell has longer electron recombination time as well as electron transport time than pure TiO2 cell. The charge collection efficiency of TiO2-NaYF4:Yb(3+)/Er(3+) cell was little lower than that of pure TiO2 cell. In addition, the interfacial resistance of the TiO2-dye|I3(-)/I(-) electrolyte interface of TiO2-NaYF4:Yb(3+)/Er(3+) cell was much bigger than that of pure TiO2 cell. All these results indicated that the charge transport cannot be improved by adding NaYF4:Yb(3+)/Er(3+). And thus, the enhanced photoelectric conversion efficiencies of TiO2-NaYF4:Yb(3+)/Er(3+) cells were closely related to the dual-mode luminescent function of NaYF4:Yb(3+)/Er(3+). PMID:23455429

Li, Ying; Pan, Kai; Wang, Guofeng; Jiang, Baojiang; Tian, Chungui; Zhou, Wei; Qu, Yang; Liu, Shuai; Feng, Li; Fu, Honggang

2013-03-01

376

The modality of cell-particle interactions drives the toxicity of nanosized CuO and TiO2 in human alveolar epithelial cells.  

PubMed

Metal oxide NPs are abundantly produced in nanotech industries and are emitted in several combustion processes, suggesting the need to characterize their toxic impact on the human respiratory system. The acute toxicity and the morphological changes induced by copper oxide and titanium dioxide NPs (nCuO and nTiO2) on the human alveolar cell line A549 are here investigated. Cell viability and oxidative stress have been studied in parallel with NP internalization and cell ultrastructural modifications. TiO2 NPs were abundantly internalized by cells through the endocytic pathway, even they did not induce cell death and ultrastructural lesions. Only after 24h cells were affected by an abundant NP internalization presenting a consequent altered morphology. High cytotoxicity, oxidative stress and severe ultrastructural damages were produced by nCuO, since cell membrane and mitochondria resulted to be heavily affected, even at early exposure time. nCuO-induced toxicity has been interpreted as a consequence of both NPs reactivity and copper ions dissolution in lysosomal compartments, even the free NPs, scattered throughout all the cell compartments, might contribute to the toxicity. The antioxidant N-acetylcysteine was effective in recovering nCuO exposed cells viability and Bafilomycin A1 inhibited copper ions release in phagolysosomes and significantly rescued cells, suggesting a relevant cytotoxic mechanism relative to oxidative damages and authophagic cell death, together with NP internalization and dissolution. Our results support the previous data reporting CuO NPs are highly cytotoxic and genotoxic, and associate their toxic effects with their cell penetration and interaction with various compartments. In conclusion, the so-called "Trojan horse" mechanism and autophagy, are involved in nCuO-induced cell death, even a further research is needed to explain the events occurring at early exposure time. PMID:23906720

Moschini, Elisa; Gualtieri, Maurizio; Colombo, Miriam; Fascio, Umberto; Camatini, Marina; Mantecca, Paride

2013-07-29

377

Performance improvement of phase-change memory cell using AlSb3Te and atomic layer deposition TiO2 buffer layer  

PubMed Central

A phase change memory (PCM) cell with atomic layer deposition titanium dioxide bottom heating layer is investigated. The crystalline titanium dioxide heating layer promotes the temperature rise in the AlSb3Te layer which causes the reduction in the reset voltage compared to a conventional phase change memory cell. The improvement in thermal efficiency of the PCM cell mainly originates from the low thermal conductivity of the crystalline titanium dioxide material. Among the various thicknesses of the TiO2 buffer layer, 4 nm was the most appropriate thickness that maximized the improvement with negligible sacrifice of the other device performances, such as the reset/set resistance ratio, voltage window, and endurance.

2013-01-01

378

Recent advances in visible-light-responsive photocatalysts for hydrogen production and solar energy conversion--from semiconducting TiO2 to MOF/PCP photocatalysts.  

PubMed

The present perspective describes recent advances in visible-light-responsive photocatalysts intended to develop novel and efficient solar energy conversion technologies, including water splitting and photofuel cells. Water splitting is recognized as one of the most promising techniques to convert solar energy as a clean and abundant energy resource into chemical energy in the form of hydrogen. In recent years, increasing concern is directed to not only the development of new photocatalytic materials but also the importance of technologies to produce hydrogen and oxygen separately. Photofuel cells can convert solar energy into electrical energy by decomposing bio-related compounds and livestock waste as fuels. The advances of photocatalysts enabling these solar energy conversion technologies have been going on since the discovery of semiconducting titanium dioxide materials and have extended to organic-inorganic hybrid materials, such as metal-organic frameworks and porous coordination polymers (MOF/PCP). PMID:23760469

Horiuchi, Yu; Toyao, Takashi; Takeuchi, Masato; Matsuoka, Masaya; Anpo, Masakazu

2013-08-28

379

Toxicity assessment of metoprolol and its photodegradation mixtures obtained by using different type of TiO2 catalysts in the mammalian cell lines.  

PubMed

Toxicity of metoprolol (MET) alone and in mixtures with its photocatalytic degradation intermediates obtained by using TiO2 Wackherr and Degussa P25 under UV irradiation in the presence of O2 was evaluated in vitro in a panel of three histologically different cell lines: rat hepatoma (H-4-II-E), human colon adenocarcinoma (HT-29) and human fetal lung (MRC-5). Both catalysts promoted a time-dependent increase in the toxicity of the photodegradation products, and those obtained using Degussa P25 photocatalyst were more toxic. The most pronounced and selective toxic action of MET and products of its photodegradation was observed in the hepatic cell line. The higher toxicity of the mixtures obtained using Degussa P25 catalyst could be explained by a different mechanism of MET degradation, i.e. by the presence or higher concentrations of some intermediates. Although the concentrations of intermediates obtained using TiO2 Wackherr catalyst were higher, they did not affect significantly the growth of the examined cell lines, indicating their lower toxicity. This suggests that a treatment aiming at complete mineralization should be performed bearing in mind that the type of catalyst, the concentration of target molecule, and the duration of the process are significant factors that determine the nature and toxicity of the resulting mixtures. Although the EC50 values of MET obtained in mammalian cell lines were higher compared to the bioassays for lower trophic levels, the time-dependent promotion of toxicity of degradation mixtures should be attributed to the higher sensitivity of mammalian cell bioassays. PMID:23872187

Cetojevi?-Simin, Dragana D; Armakovi?, Sanja J; Soji?, Daniela V; Abramovi?, Biljana F

2013-07-17

380

Efficiency enhancements in Ag nanoparticles-SiO2-TiO2 sandwiched structure via plasmonic effect-enhanced light capturing  

PubMed Central

TiO2-SiO2-Ag composites are fabricated by depositing TiO2 films on silica substrates embedded with Ag nanoparticles. Enhancement of light absorption of the nanostructural composites is observed. The light absorption enhancement of the synthesized structure in comparison to TiO2 originated from the near-field enhancement caused by the plasmonic effect of Ag nanoparticles, which can be demonstrated by the optical absorption spectra, Raman scattering investigation, and the increase of the photocatalytic activity. The embedded Ag nanoparticles are formed by ion implantation, which effectively prevents Ag to be oxidized through direct contact with TiO2. The suggested incorporation of plasmonic nanostructures shows a great potential application in a highly efficient photocatalyst and ultra-thin solar cell.

2013-01-01

381

Efficiency enhancements in Ag nanoparticles-SiO2-TiO2 sandwiched structure via plasmonic effect-enhanced light capturing  

NASA Astrophysics Data System (ADS)

TiO2-SiO2-Ag composites are fabricated by depositing TiO2 films on silica substrates embedded with Ag nanoparticles. Enhancement of light absorption of the nanostructural composites is observed. The light absorption enhancement of the synthesized structure in comparison to TiO2 originated from the near-field enhancement caused by the plasmonic effect of Ag nanoparticles, which can be demonstrated by the optical absorption spectra, Raman scattering investigation, and the increase of the photocatalytic activity. The embedded Ag nanoparticles are formed by ion implantation, which effectively prevents Ag to be oxidized through direct contact with TiO2. The suggested incorporation of plasmonic nanostructures shows a great potential application in a highly efficient photocatalyst and ultra-thin solar cell.

Xu, Jinxia; Xiao, Xiangheng; Stepanov, Andrey L.; Ren, Fen; Wu, Wei; Cai, Guangxu; Zhang, Shaofeng; Dai, Zhigao; Mei, Fei; Jiang, Changzhong

2013-02-01

382

Preparation of meso-porous TiO 2 gels and their characterization  

Microsoft Academic Search

Mesoporous TiO2 gels, which are attractive for their potential application to photocatalysts and electrodes for wet solar cells, have been prepared by a newly developed method and their microstructure was investigated. Monolithic gels were obtained by hydrolysis of Ti(n-C4H9O)4 in an ethanol\\/ethylacetoacetate solution. The wet gels were aged and dried after immersion in an ethanol solution of surfactants, cetyltrimethylammonium chloride

Hiroshi Hirashima; Hiroaki Imai; Vladimir Balek

2001-01-01

383

Self-Assembly of Large-Scale Floating TiO2 Nanorod Arrays at the Gas-Liquid Interface.  

PubMed

This paper describes a facile one-step synthesis of large-scale floating TiO2 nanorod arrays via a hydrothermal reaction without using any surfactants, which opens a new way to prepare floating photocatalysts for photodecomposition of floating organics and free-standing nanorod arrays for flexible dye-sensitized solar cells. A general model is developed to analyze the driving force for the floating TiO2 film, which may be also useful for other two-dimensional materials to determine the obtainable size of an arbitrary shaped film floated by surface tension and buoyancy. PMID:23992522

Xia, Hua-Rong; Li, Jia; Peng, Chen; Li, Long-Wei; Sun, Wen-Tao; Peng, Lian-Mao

2013-09-04

384

Modeling of trap assisted interfacial charge transfer in dye sensitized solar cells  

NASA Astrophysics Data System (ADS)

This paper presents a model for charge transport in dye sensitized solar cells based on the physics of electron capture, electron emission, oxidation, and reduction processes mediated by deep interfacial trap states at TiO2/dye/electrolyte interfaces. This model suggests that electron back injection from the conduction band of TiO2 to electrolyte is due to trapping of conduction band electrons by deep states followed by reduction processes at the interface. The simulated dark IV, illuminated IV, and quantum efficiency characteristics of dye sensitized solar cells based on this model are consistent with experimental results.

Nepal, Jeevan; Sadegh Mottaghian, Seyyed; Biesecker, Matt; Farrokh Baroughi, Mahdi

2013-05-01

385

Influence of cell fabrication procedure on the performance of the dye sensitized solar cell.  

PubMed

The recent technological advancements of the Dye Sensitized Solar Cells (DSSCs) fabrication technology is gaining momentum as a low cost and simple fabrication technology to convert solar energy into electric energy. A systematic study of the DSSC fabrication procedure and its influence on the cell efficiency are presented in this paper. Preparation of the titanium dioxide (TiO2) layer on the working electrode was the most significant process improvement made to enhance cell efficiency. The Coatema tool was used to develop an automated TiO2 coating process, which yielded layer thicknesses with minimum micro cracks and repeatable TiO2 weight loading in the range of 8-13 microm. Secondary process improvements implemented were: vacuum drying step for the TiO2 layer, dilution ratio of the sensitized dye and sealant thickness. These optimized cell fabrication steps enhanced cell efficiencies over 200% and reduced total process time. The work in progress demonstrated higher cell efficiency slightly greater than 9% by reducing the cell size using the optimized fabrication process described in this paper. We are confident that higher efficiency cells can be fabricated with this optimized fabrication process illustrated in this paper. PMID:22754987

Jen, C Y; Munukutla, L V; Radhakrishnan, S; Kannan, A M; Htun, A

2012-03-01

386

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

387

Pilot-plant treatment of olive mill wastewater (OMW) by solar TiO 2 photocatalysis and solar photo-Fenton  

Microsoft Academic Search

Olive mill wastewater (OMW), a highly polluted wastewater from the olive oil industry, was treated by solar photocatalysis and solar photo-Fenton. Among the tested systems the application of titanium dioxide alone was not successful. The addition of peroxydisulphate as an electron acceptor had only limited effect on degradation performance and led to high salt concentrations (30 g\\/l sulphate generated) and

W. Gernjak; M. I. Maldonado; S. Malato; J. Cáceres; T. Krutzler; A. Glaser; R. Bauer

2004-01-01

388

Hierarchically Structured ZnO Film for Dye-Sensitized Solar Cells with Enhanced Energy Conversion Efficiency  

SciTech Connect

The interest in dye-sensitized solar cells has increased due to reduced energy sources and higher energy production costs. For the most part, titania (TiO2) has been the material of choice for dye-sensitized solar cells and so far have shown to exhibit the highest overall light conversion efficiency ~ 11%.[1] However, zinc oxide (ZnO) has recently been explored as an alternative material in dye-sensitized solar cells with great potential.[2] The main reasons for this increase in research surrounding ZnO material include: 1) ZnO having a band gap similar to that for TiO2 at 3.2 eV,[3] and 2) ZnO having a much higher electron mobility ~ 115-155 cm2/Vs[4] than that for anatase titania (TiO2), which is reported to be ~ 10-5 cm2/Vs.[5] In addition, ZnO has a few advantages as the semiconductor electrode when compared to TiO2, including 1) simpler tailoring of the nanostructure as compared to TiO2, and 2) easier modification of the surface structure. These advantages[6] are thought to provide a promising means for improving the solar cell performance of the working electrode in dye-sensitized solar cells.

Chou, Tammy P.; Zhang, Qifeng; Fryxell, Glen E.; Cao, Guozhong

2007-09-17

389

Improved hybrid solar cells via in situ UV polymerization.  

PubMed

One approach for making inexpensive inorganic-organic hybrid photovoltaic (PV) cells is to fill highly ordered TiO(2) nanotube (NT) arrays with solid organic hole conductors such as conjugated polymers. Here, a new in situ UV polymerization method for growing polythiophene (UV-PT) inside TiO(2) NTs is presented and compared to the conventional approach of infiltrating NTs with pre-synthesized polymer. A nanotubular TiO(2) substrate is immersed in a 2,5-diiodothiophene (DIT) monomer precursor solution and then irradiated with UV light. The selective UV photodissociation of the C--I bond produces monomer radicals with intact pi-ring structure that further produce longer oligothiophene/PT molecules. Complete photoluminescence quenching upon UV irradiation suggests coupling between radicals created from DIT and at the TiO(2) surface via a charge transfer complex. Coupling with the TiO(2) surface improves UV-PT crystallinity and pi-pi stacking; flat photocurrent values show that charge recombination during hole transport through the polymer is negligible. A non-ideal, backside-illuminated setup under illumination of 620-nm light yields a photocurrent density of approximately 5 microA cm(2)-surprisingly much stronger than with comparable devices fabricated with polymer synthesized ex situ. Since in this backside architecture setup we illuminate the cell through the Ag top electrode, there is a possibility for Ag plasmon-enhanced solar energy conversion. By using this simple in situ UV polymerization method that couples the conjugated polymer to the TiO(2) surface, the absorption of sunlight can be improved and the charge carrier mobility of the photoactive layer can be enhanced. PMID:19367599

Tepavcevic, Sanja; Darling, Seth B; Dimitrijevic, Nada M; Rajh, Tijana; Sibener, Steven J

2009-08-01

390

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

391

Localized control of light-matter interactions by using nanoscale asymmetric TiO2.  

PubMed

This paper reports an asymmetry structure-mediated route for highly localized control of light-matter interactions by using tapered TiO(2). We demonstrate for the first time that the growth habit of Ag nanostructures on tapered TiO(2) can be tuned by controllable photolysis. Site-selective anchoring of Ag nanoparticles or nanowires on tapered TiO(2) can be achieved by simply changing the external light. We further show that the obtained tapered TiO(2)-Ag hetero-nanostructures present excellent light-trapping ability over a wide range of wavelengths which is considered to originate from the unique synergistic effects of graded waveguiding and plasmonic light trapping. This improved photon-management capability renders the prepared substrate a very promising candidate for optical sensing application. For this purpose, an enhanced sensitivity for trace detection is confirmed. These findings open up promising avenues for tailoring of light-matter interactions which are of special interest for studying controllable photolysis activation processes and diverse applications such as nanostructure growth, trace detection, photocatalysis and solar cells. PMID:23093286

Zhou, Shifeng; Matsuoka, Tomoyo; Shimotsuma, Yasuhiko; Sakakura, Masaaki; Nishi, Masayuki; Hong, Zhanglian; Qiu, Jianrong; Hirao, Kazuyuki; Miura, Kiyotaka

2012-10-23

392

Preparation of grass-like TiO2 nanostructure thin films: Effect of growth temperature  

NASA Astrophysics Data System (ADS)

TiO2 nanoparticles with various morphologies have been synthesized under various temperature conditions, namely 25, 50, 60 and 90 °C via a liquid phase deposition technique. The liquid phase deposition technique is an electroless deposition of TiO2 onto the substrate surface via a unique hydrolysis of titanium complexes in the presence of H3BO3. FESEM characterization on the samples showed that, under the temperature treatment, the nanostructures morphology transformed from grass-like to agglomerated spherical-like shape with the increased of the temperature. The XRD analysis performed on these samples show that all of the samples were anatase and unmodified with the change in the morphology. The optical absorption window of the TiO2 nanostructures films was also found to enlarge with the increasing of the growth temperature, resulting from the structure modification. Owing to its simplicity, the present technique may produce TiO2 nanoparticles with a variety of morphologies for use in photocatalyst and solar cell applications.

Umar, A. A.; Rahman, M. Y. A.; Saad, S. K. M.; Salleh, M. M.; Oyama, M.

2013-04-01

393

Photoelectrochemical water splitting and simultaneous photoelectrocatalytic degradation of organic pollutant on highly smooth and ordered TiO 2 nanotube arrays  

Microsoft Academic Search

The photoelectrochemical water splitting and simultaneous photoelectrocatalytic degradation of organic pollutant were achieved on TiO2 nanotube electrodes with double purposes of environmental protection and renewable energy production under illumination of simulated solar light. The TiO2 nanotube arrays (TiO2 NTs) were fabricated by a two-step anodization method. The TiO2 NTs prepared in two-step anodization process (2-step TiO2 NTs) showed much better

Hongjun Wu; Zhonghai Zhang

394

Correlating titania morphology and chemical composition with dye-sensitized solar cell performance  

Microsoft Academic Search

We have investigated the use of various morphologies, including nanoparticles, nanowires, and sea-urchins of TiO2 as the semiconducting material used as components of dye-sensitized solar cells (DSSCs). Analysis of the solar cells under AM 1.5 solar irradiation reveals the superior performance of hydrothermally derived nanoparticles, by comparison with two readily available commercial nanoparticle materials, within the DSSC architecture. The sub-structural

Alexander C. Santulli; Christopher Koenigsmann; Amanda L. Tiano; Donald DeRosa; Stanislaus S. Wong

2011-01-01

395

The enhanced conductivity and stability of AZO thin films with a TiO2 buffer layer  

NASA Astrophysics Data System (ADS)

Aluminum doped zinc oxide (AZO) films were substitutes of the SnO2:F films on soda lime glass substrate in the amorphous thin-film solar cells due to good properties and low cost. In order to improve properties of AZO films, the TiO2 buffer layer had been introduced. AZO films with and without TiO2 buffer layer were deposited on soda lime glass substrates by r.f. magnetron sputtering. Subsequently, one group samples were annealed in vacuum (0.1 Pa) at 500 °C for 120 s using the RTA system, and the influence of TiO2 thickness on the properties of AZO films had been discussed. The XRD measurement results showed that all the films had a preferentially oriented (0 0 2) peak, and the intensity of (0 0 2) peak had been enhanced for the AZO films with TiO2 buffer layer. The resistivity of TiO2 (3.0 nm)/AZO double-layer film is 4.76×10-4 ? cm with the maximum figure merit of 1.92×10-2 ?-1, and the resistivity has a remarkable 28.7% decrease comparing with that of the single AZO film. The carrier scattering mechanism of TiO2 (3.0 nm)/AZO double-layer film had been described by Hall measurement in different temperatures. The average transmittance of all the films exceeded 92% in the visible spectrum. Another group samples were heat treated in the quartz tube in air atmosphere, and the effect of TiO2 thickness on thermal stability of AZO films had been discussed.

Yang, Tianlin; Song, Shumei; Li, Yanhui; Xin, Yanqing; Du, Guiqiang; Lv, Maoshui; Han, Shenghao

2012-12-01

396

Photocatalytic degradation of Crystal Violet (C.I. Basic Violet 3) on silver ion doped TiO 2  

Microsoft Academic Search

The photocatalytic degradation of Crystal Violet, a triphenyl methane dye (also known as Basic Violet 3) in aqueous solutions was investigated with Ag+ doped TiO2 under UV and simulated solar light. The dye degradation using untreated TiO2 and Ag+ doped TiO2 was compared. It was found that Ag+ doped TiO2 is slightly more efficient. Ag+ doping was done also to

C. Sahoo; A. K. Gupta; Anjali Pal

2005-01-01

397

Role of the conducting layer substrate on TiO2 nucleation when using microwave activated chemical bath deposition  

NASA Astrophysics Data System (ADS)

Nanostructured TiO2 is used in novel dye sensitized solar cells. Because of their interaction with light, thin TiO2 films are also used as coatings for self-cleaning glasses and tiles. Microwave activated chemical bath deposition represents a simple and cost-effective way to obtain nanostructured TiO2 films. It is important to study, in this technique, the role of the conducting layer used as the substrate. The influence of microwave-substrate interactions on TiO2 deposition is analysed using different substrate positions, employing substrates with different conductivities, and also using different microwave radiation powers for film deposition. We prove that a common domestic microwave oven with a large cavity and inhomogeneous radiation field can be used with equally satisfactory results. The transmittance spectra of the obtained films were studied and used to analyse film thickness and to obtain gap energy values. The results, regarding different indium-tin oxide resistivities and different substrate positions in the oven cavity, show that the interaction of the microwave field with the conducting layer is determinant in layer deposition. It has also been found that film thickness increases with the power of the applied radiation while the gap energies of the TiO2 films decrease approaching the 3.2 eV value reported for bulk anatase. This indicates that these films are not crystalline and it agrees with x-ray spectra that do not reveal any peak.

Zumeta, I.; Espinosa, R.; Ayllón, J. A.; Vigil, E.

2002-12-01

398

Anatase TiO2 nanocomposites for antimicrobial coatings.  

PubMed

A sol-gel chemistry approach was used to fabricate nanoparticles of TiO(2) in its anatase form. The particle size is shown to be sensitive to the use of HClO(4) or HNO(3) as acid catalyst. The gold-capped TiO(2) nanocomposites were processed by the reduction of gold on the surface of the TiO(2) nanoparticles via a chemical reduction or a photoreduction method. Different percentages of vanadium-doped TiO(2) nanoparticles, which extended the TiO(2) absorption wavelength from the ultraviolet to the visible region, were successfully prepared. The synthesized nanocomposites have a size of about 12-18 nm and an anatase phase as characterized by XRD, TEM, AFM, and UV-vis spectroscopy. The TiO(2) nanocomposite coatings have been applied on glass slide substrates. The antibacterial activity of TiO(2) nanocomposites was investigated qualitatively and quantitatively. Two types of bacteria, Escherichia coli (DH 5alpha) and Bacillus megaterium (QM B1551), were used during the experiments. Good inhibition results were observed and demonstrated visually. The quantitative examination of bacterial activity for E. coli was estimated by the survival ratio as calculated from the number of viable cells, which form colonies on the nutrient agar plates. The antimicrobial efficiency and inhibition mechanisms are illustrated and discussed. PMID:16852057

Fu, Guifen; Vary, Patricia S; Lin, Chhiu-Tsu

2005-05-12

399

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\\cdotm-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; Miankushki, Hoda Nourmohammadi

2013-07-01

400

Photoelectrochemical characteristics of semiconductor-metal/SPE/metal cells  

SciTech Connect

A solid polymer electrolyte (SPE) photoelectrochemical cell, semiconductor-metal/SPE/Pt, is proposed as a new device to convert solar energy to electrical and/or chemical energy. The photoelectrochemical characteristics of TiO2-Pt/SPE and TiO2-Au/SPE were studied as well as those of the whole cell systems TiO2-Pt/SPE/Pt and TiO2-Au/SPE/Pt. By above-band gap energy illumination of the TiO2-metal side, negative photovoltage and anodic photocurrent were observed, as reported at TiO2 electrodes. In whole cell systems, i.e., TiO2-Pt/SPE/Pt and TiO2-Au/SPE/Pt, the conversion of light to electricity was achieved without using electrolyte solution.

Uosaki, K.; Kita, H.

1983-11-01

401

Arsenic removal from water employing heterogeneous photocatalysis with TiO 2 immobilized in PET bottles  

Microsoft Academic Search

Arsenic oxidation (As(III) to As(V)) and As(V) removal from water were assessed by using TiO2 immobilized in PET (polyethylene terephthalate) bottles in the presence of natural sunlight and iron salts. The effect of many parameters was sequentially studied: TiO2 concentration of the coating solution, Fe(II) concentration, pH, solar irradiation time; dissolved organic carbon concentration. The final conditions (TiO2 concentration of

Anne Hélène Fostier; Maria do Socorro Silva Pereira; Susanne Rath; José Roberto Guimarães

2008-01-01

402

Recent Advances in Sensitized Solar Cells  

NASA Astrophysics Data System (ADS)

Understanding the principal physical and chemical factors that govern or limit cell performance is critical for underpinning the development of next-generation sensitized solar cells. Recent studies of dye-sensitized solar cells (DSSCs) covering nanoporous (pore diameter <100 nm) one-dimensional TiO2 nanostructured arrays and molecular voltage enhancers are discussed. Films constructed of oriented one-dimensional nanostructures, such as nanotube arrays, which are aligned perpendicularly to the charge-collecting substrate, could potentially improve the charge-collection efficiency by promoting faster transport and/or slower recombination. The extent to which transport or recombination could be affected by an oriented architecture is expected to depend on the influence of other mechanistic factors, such as the density and location of defects, crystallinity, and film uniformity. Orientational disorder within the nanotube array could also influence the transport and recombination kinetics. Such architectural disorder in titanium dioxide films is shown to have a strong influence on the transport, recombination, and light-harvesting properties of DSSCs. The mechanism by which molecular adsorbents alter the photovoltage of DSSCs is dependent on the properties of the adsorbent. In principle, an adsorbent could affect the photovoltage by either altering the recombination rate of photoelectrons in TiO2 with oxidized redox species in the electrolyte or inducing band-edge movement. The net effect of altering the band positions and recombination kinetics can either improve or diminish cell performance. The mechanisms by which several molecular adsorbents increase the photovoltage of DSSCs are discussed.

Frank, Arthur J.

403

Solar Cells and Solar Panels.  

National Technical Information Service (NTIS)

The bibliography is a selection of unclassified and unlimited distribution references on Solar Cells and Solar Panels. These citations of reports present information on performance characteristics, fabrication, development of power levels, degradation stu...

1973-01-01

404

Dye-sensitized solar cells based on free-standing titanium dioxide nanotube arrays  

NASA Astrophysics Data System (ADS)

Dye-sensitized solar cells (DSSCs) are photoelectrochemical cells using wide band gap nanoporous oxide semiconductors sensitized by dey molecules. DSSCs generally consist of photosensitive dye molecules and a titanium dioxide (TiO2) nanoparticle network. DSSCs convert light energy to electrical energy through photo-excitation of dye molecules anchored to the surface of TiO2 nanoparticles, electron injection and transport in the TiO 2 nanoparticle network. DSSCs attracted great attention due to their respectable efficiency with very low fabrication cost, good performance under diffuse light conditions, semi-transparency and multi color range possibilities, and the ability to be fabricated on flexible substrates. Its main efficiency limiting factor is the random hopping of electrons within the TiO2 nanoparticle network, which causes carrier trapping and recombination. The charge transport and collection can be enhanced by employing ordered nanostructures such as nanowire or nanotube arrays. However, DSSCs based on nanowire or nanotube arrays with power conversion efficiency higher than 11.18% achieved from the conventional DSSCs have yet to be demonstrated. This dissertation focuses on the development of DSSCs using highly crystalline free-standing TiO2 nanotube (FSTNT) arrays to enhance charge transport and collection, and hence, power conversion efficiency. TiO2 nanotube arrays were obtained by potentiostatic anodization of titanium foil in fluoride-based ethylene glycol electrolyte. TiO2 nanotube arrays were detached from the titanium foil by chemical etching and annealed at high temperatures to obtain highly crystalline anatase phase FSTNT arrays. DSSCs based on FSTNT arrays revealed high power conversion efficiency of 13.2% and short-circuit photocurrent density comparable to that of monocrystalline silicon solar cell.

Kim, Chaehyun

405

Comparative study of ZnO and TiO(2) nanoparticles: physicochemical characterisation and toxicological effects on human colon carcinoma cells.  

PubMed

Abstract Despite human gastrointestinal exposure to nanoparticles (NPs), data on NPs toxicity in intestinal cells are quite scanty. In this study we evaluated the toxicity induced by zinc oxide (ZnO) and titanium dioxide (TiO(2)) NPs on Caco-2 cells. Only ZnO NPs produced significant cytotoxicity, evaluated by two different assays. The presence of foetal calf serum in culture medium significantly reduced ZnO NPs toxicity as well as ion leakage and NP-cell interaction. The two NPs increased the intracellular amount of reactive oxygen species (ROS) after 6 h treatment. However, only ZnO NPs increased ROS and induced IL-8 release both after 6 and 24 h. Experimental data indicate a main role of chemical composition and solubility in ZnO NPs toxicity. Moreover our results suggest a key role of oxidative stress in ZnO NPs cytotoxicity induction related both to ion leakage and to cell interaction with NPs in serum-free medium. PMID:23078188

De Angelis, Isabella; Barone, Flavia; Zijno, Andrea; Bizzarri, Loreline; Russo, Maria Teresa; Pozzi, Roberta; Franchini, Fabio; Giudetti, Guido; Uboldi, Chiara; Ponti, Jessica; Rossi, Francois; De Berardis, Barbara

2012-11-01

406

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.

407

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

408

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

2011-03-15

409

Efficient sintering of nanocrystalline titanium dioxide films for dye solar cells via raster scanning laser  

NASA Astrophysics Data System (ADS)

By identifying the right combination of laser parameters, in particular the integrated laser fluence ?, we fabricated dye solar cells (DSCs) with UV laser-sintered TiO2 films exhibiting a power conversion efficiency ?=5.2%, the highest reported for laser-sintered devices. ? is dramatically affected by ? and a clear trend is reported. Significantly, DSCs fabricated by raster scanning the laser beam to sinter the TiO2 films are made as efficient as those with oven-sintered ones. These results, confirmed on three batches of cells, demonstrate the remarkable potential (noncontact, local, low cost, rapid, selective, and scalable) of scanning laser processing applied to DSC technology.

Mincuzzi, Girolamo; Vesce, Luigi; Reale, Andrea; di Carlo, Aldo; Brown, Thomas M.

2009-09-01

410

Layer-by-layer self assembly deposition and characterization of TiO{2} nanoparticles by using a short chain polycation  

NASA Astrophysics Data System (ADS)

Using low molecular weight polyethylenimine (PEI), transparent thin films of TiO{2} nanoparticles were prepared by layer-by-layer self assembly method. UV-visible spectrophotometry was employed in a quantitative manner to monitor the adsorbed mass of TiO{2} and PEI after each dip cycle. The adsorption of both TiO{2} and PEI showed a saturation dip time of 10 min. The effect of dip time on the growth mode and surface morphology was investigated by scanning electron microscopy (SEM) and non-contact atomic force microscopy (AFM). It was found that growth proceeds in the form of laterally broad islands in case of short dip times, and taller but laterally smaller islands in case of longer dip times. A model was proposed which describes the role of dip time on the lateral growth of TiO{2} islands. Low molecular weight PEI resulted in around 25% less adsorption of PEI and TiO{2} in comparison with high molecular weight PEI, but because of lower remaining ash, could be promising for dye-sensitized solar cell photoelectrode applications, in which removal of polyelectrolyte after the formation of thin film enhances the electrical properties and therefore the efficiency of solar cell.

Rahman, M.; Taghavinia, N.

2009-10-01

411

Production of TiO2 crystalline nanoparticles by laser ablation in ethanol  

NASA Astrophysics Data System (ADS)

TiO2 nanoparticles have received a special attention due to their applications in many different fields, such as catalysis, biomedical engineering, and energy conversion in solar cells. In this paper we report on the production of TiO2 nanoparticles by means of a pulsed laser to ablate titanium metallic target submerged in ethanol. The results show that titanium crystalline dioxide nanoparticles can be obtained in a narrow size distribution. Crystalline phases, morphology and optical properties of the obtained colloidal nanoparticles were characterized by means of X-ray diffraction (XRD), transmission electron microscopy (TEM), high resolution transmission electron microscopy (HRTEM) and UV/vis absorption spectroscopy. The produced particles consisted mainly of titanium oxide crystalline nanoparticles showing spherical shape with most diameters ranging from 5 to 50 nm. Nanoparticles are polycrystalline exhibiting the coexistence of the three main phases with the predominance of brookite.

Boutinguiza, M.; Rodriguez-Gonzalez, B.; del Val, J.; Comesaña, R.; Lusquiños, F.; Pou, J.

2012-09-01

412

Evaluating Microtox as a tool for biodegradability assessment of partially treated solutions of pesticides using Fe3+ and TiO2 solar photo-assisted processes.  

PubMed

To shorten phototreatment time is of major concern for the cost and energy benefits of the xenobiotics degradation performed by photocatalytic processes. Using photo-Fenton and TiO(2) phototreatments, partially photodegraded solutions of 6 separate pesticides (alachlor, atrazine, chlorfenvinphos, diuron, isoproturon and pentachlorophenol) were tested for biocompatibility, which was evaluated according to the Zahn-Wellens procedure. This study investigated if Microtox could be considered as a suitable global indicator capable of giving information on the evolution of biocompatibility of the water solution contaminated with organic pollutants during the phototreatment in order to promote biotreatment. The obtained results demonstrated that biodegradability increased significantly after short photo-Fenton treatment times for alachlor, diuron and pentachlorophenol. Uncertain results were obtained with atrazine and isoproturon. Microtox acute toxicity testing was shown to correctly represent dynamics and efficiency of phototreatment. PMID:18155146

Lapertot, Milena; Ebrahimi, Sirous; Oller, Isabel; Maldonado, Manuel I; Gernjak, Wolfgang; Malato, Sixto; Pulgarín, César

2007-12-21

413

Use of fluorine-doped tin oxide instead of indium tin oxide in highly efficient air-fabricated inverted polymer solar cells  

Microsoft Academic Search

The stability and efficiency of organic solar cells (OSCs) were improved using thermally stable fluorine-doped tin oxide (FTO) as the bottom electrode and poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) and TiO2 as the buffer layers. The TiO2 layer between FTO and the P3HT:PCBM active layer improved the interface characteristics for a better charge transfer. The PEDOT:PSS layer retarded the oxygen diffusion to the active

Woon-Hyuk Baek; Mijung Choi; Tae-Sik Yoon; Hyun Ho Lee; Yong-Sang Kim

2010-01-01

414

Genotoxicity of inhaled nanosized TiO(2) in mice.  

PubMed

In vitro studies have suggested that nanosized titanium dioxide (TiO(2)) is genotoxic. The significance of these findings with respect to in vivo effects is unclear, as few in vivo studies on TiO(2) genotoxicity exist. Recently, nanosized TiO(2) administered in drinking water was reported to increase, e.g., micronuclei (MN) in peripheral blood polychromatic erythrocytes (PCEs) and DNA damage in leukocytes. Induction of micronuclei in mouse PCEs was earlier also described for pigment-grade TiO(2) administered intraperitoneally. The apparent systemic genotoxic effects have been suggested to reflect secondary genotoxicity of TiO(2) due to inflammation. However, a recent study suggested that induction of DNA damage in mouse bronchoalveolar lavage (BAL) cells after intratracheal instillation of nanosized or fine TiO(2) is independent of inflammation. We examined here, if inhalation of freshly generated nanosized TiO(2) (74% anatase, 26% brookite; 5 days, 4 h/day) at 0.8, 7.2, and (the highest concentration allowing stable aerosol production) 28.5 mg/m(3) could induce genotoxic effects in C57BL/6J mice locally in the lungs or systematically in peripheral PCEs. DNA damage was assessed by the comet assay in lung epithelial alveolar type II and Clara cells sampled immediately following the exposure. MN were analyzed by acridine orange staining in blood PCEs collected 48 h after the last exposure. A dose-dependent deposition of Ti in lung tissue was seen. Although the highest exposure level produced a clear increase in neutrophils in BAL fluid, indicating an inflammatory effect, no significant effect on the level of DNA damage in lung epithelial cells or micronuclei in PCEs was observed, suggesting no genotoxic effects by the 5-day inhalation exposure to nanosized TiO(2) anatase. Our inhalation exposure resulted in much lower systemic TiO(2) doses than the previous oral and intraperitoneal treatments, and lung epithelial cells probably received considerably less TiO(2) than BAL cells in the earlier intratracheal study. PMID:22094288

Lindberg, Hanna K; Falck, Ghita C-M; Catalán, Julia; Koivisto, Antti J; Suhonen, Satu; Järventaus, Hilkka; Rossi, Elina M; Nykäsenoja, Heli; Peltonen, Yrjö; Moreno, Carlos; Alenius, Harri; Tuomi, Timo; Savolainen, Kai M; Norppa, Hannu

2011-11-07

415

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

416

Growing TiO2 nanowires on the surface of graphene sheets in supercritical CO2: characterization and photoefficiency.  

PubMed

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 TiO(2) 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 (scCO(2)). The effect of scCO(2) 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 scCO(2) resulted in increasing the TiO(2) nanowire diameter from 10 to 40 nm. Raman and high resolution XPS showed the interaction of TiO(2) 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 TiO(2) nanowires. Photocurrent measurements showed that the TiO(2)nanowire/graphene composites prepared in scCO(2) gave a 5× enhancement in photoefficiency compared to bare TiO(2) nanowires. PMID:22743625

Farhangi, Nasrin; Medina-Gonzalez, Yaocihuatl; Chowdhury, Rajib Roy; Charpentier, Paul A

2012-06-28

417

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.

Farhangi, Nasrin; Medina-Gonzalez, Yaocihuatl; Chowdhury, Rajib Roy; Charpentier, Paul A.

2012-07-01

418

A dielectrophoresis-based microdevice coated with nanostructured TiO 2 for separation of particles and cells  

Microsoft Academic Search

In this study, we present a microdevice coated with titanium dioxide for cells and particles separation and handling. The\\u000a microsystem consists of a pair of planar interdigitated gold micro-electrode arrays on a quartz substrate able to generate\\u000a a traveling electric completed with a microfabricated three-dimensional glass structure for cell confinement. Dielectrophoretic\\u000a forces were exploited for both vertical and lateral cell

E. Morganti; C. Collini; R. Cunaccia; A. Gianfelice; L. Odorizzi; A. Adami; L. Lorenzelli; E. Jacchetti; A. Podestà; C. Lenardi; P. Milani

2011-01-01

419

6.5% efficient perovskite quantum-dot-sensitized solar cell  

Microsoft Academic Search

Highly efficient quantum-dot-sensitized solar cell is fabricated using ca. 2-3 nm sized perovskite (CH3NH3)PbI3 nanocrystal. Spin-coating of the equimolar mixture of CH3NH3I and PbI2 in gamma-butyrolactone solution (perovskite precursor solution) leads to (CH3NH3)PbI3 quantum dots (QDs) on nanocrystalline TiO2 surface. By electrochemical junction with iodide\\/iodine based redox electrolyte, perovskite QD-sensitized 3.6 mum-thick TiO2 film shows maximum external quantum efficiency (EQE)

Jeong-Hyeok Im; Chang-Ryul Lee; Jin-Wook Lee; Sang-Won Park; Nam-Gyu Park

2011-01-01

420

High efficiency CdSe quantum-dot sensitized solar cells  

Microsoft Academic Search

High quality CdSe quantum-dot (QD) sensitized solar cells have been successfully fabricated by in-situ deposition of QDs into TiO2 nanoporous electron conductor (EC) films using a near room-temperature solution-based chemical bath deposition (CBD) method. An energy conversion efficiency of 4.44% under AM1.5G illumination is achieved on a device fabricated using CdSe QDs as a light absorber, TiO2 nanoparticles as an

Zhi Zheng; Linan Zhao; Marilyn Wang; Minling Liu; Matthew S. Marcus; Yue Liu

2010-01-01

421

Continuous-time random-walk model of electron transport in nanocrystalline TiO2 electrodes  

Microsoft Academic Search

Electronic junctions made from porous, nanocrystalline TiO2 films in contact with an electrolyte are important for applications such as dye-sensitized solar cells. They exhibit anomalous electron transport properties: extremely slow, nonexponential current and charge recombination transients, and intensity-dependent response times. These features are attributed to a high density of intraband-gap trap states. Most available models of the electron transport are

Jenny Nelson

1999-01-01

422

Growing TiO2 nanowires on the surface of graphene sheets in supercritical CO2: characterization and photoefficiency  

Microsoft Academic Search

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

Nasrin Farhangi; Yaocihuatl Medina-Gonzalez; Rajib Roy Chowdhury; Paul A Charpentier

2012-01-01

423

Structural, morphological, and optical properties of TiO2 thin films synthesized by the electro phoretic deposition technique  

NASA Astrophysics Data System (ADS)

In this work, we report the structural, morphological, and optical properties of TiO2 thin films synthesized by the electro phoretic deposition technique. The TiO2 film was formed on a doped fluorine tin oxide (SnO2:F, i.e., FTO) layer and used as a photo electrode in a dye solar cell (DSC). Using spectroscopic ellipsometry measurements in the 200 to 800 nm wavelengths domain, we obtain a thickness of the TiO2 film in the range of 70 to 80 nm. Characterizations by X-ray diffraction and atomic force microscopy (AFM) show a polycrystalline film. In addition, AFM investigation shows no cracks in the formed layer. Using an ultraviolet-visible near-infrared spectrophotometer, we found that the transmittance of the TiO2 film in the visible domain reaches 75%. From the measured current-voltage or I-V characteristic under AM1.5 illumination of the formed DSC, we obtain an open circuit voltage V oc = 628 mV and a short circuit current I sc = 22.6 ?A, where the surface of the formed cell is 3.14 cm2.

Ghrairi, Najla; Bouaicha, Mongi

2012-07-01

424

Structural, morphological, and optical properties of TiO2 thin films synthesized by the electro phoretic deposition technique.  

PubMed

In this work, we report the structural, morphological, and optical properties of TiO2 thin films synthesized by the electro phoretic deposition technique. The TiO2 film was formed on a doped fluorine tin oxide (SnO2:F, i.e., FTO) layer and used as a photo electrode in a dye solar cell (DSC). Using spectroscopic ellipsometry measurements in the 200 to 800?nm wavelengths domain, we obtain a thickness of the TiO2 film in the range of 70 to 80?nm. Characterizations by X-ray diffraction and atomic force microscopy (AFM) show a polycrystalline film. In addition, AFM investigation shows no cracks in the formed layer. Using an ultraviolet-visible near-infrared spectrophotometer, we found that the transmittance of the TiO2 film in the visible domain reaches 75%. From the measured current-voltage or I-V characteristic under AM1.5 illumination of the formed DSC, we obtain an open circuit voltage Voc?=?628?mV and a short circuit current Isc?=?22.6??A, where the surface of the formed cell is 3.14?cm2. PMID:22747886

Ghrairi, Najla; Bouaicha, Mongi

2012-07-01

425

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

PubMed

Track-etched polycarbonate (PC) membranes were used as a soft template to synthesize mesoporous TiO(2) 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, TiO(2) nanowires (15TNW) were obtained from PC with a 15 nm pore diameter, whereas TiO(2) 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 TiO(2) 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 TiO(2) and were used as interfacial layers between the FTO glass and the 4 ?m thick nanocrystalline TiO(2) 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. PMID:21894346

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

2011-09-06

426

Nanocomposite titanium dioxide\\/polymer photovoltaic cells: effects of TiO2 microstructure, time and illumination power  

Microsoft Academic Search

Nanocomposite titanium dioxide\\/polymer photovoltaic cells have been fabricated using poly(2-(2-ethylhexyloxy)-5- methoxy-1,4-phenylenevinylene) (MEHPPV). Two different types of titanium dioxide were used, one synthesized using a sol-gel method, the other was a commercial paste. The crystal structure, porosity and absorption spectra of the titanium dioxide layers were measured, and the titanium dioxide synthesized using the sol-gel method had a much lower level

Michelle J. Carey; Victor M. Burlakova; Bernard M. Henry; Kiril R. Kirov; Graham R. Webster

427

Nanocomposite titanium dioxide\\/polymer photovoltaic cells: effects of TiO2 microstructure, time, and illumination power  

Microsoft Academic Search

Nanocomposite titanium dioxide\\/polymer photovoltaic cells have been fabricated using poly[2-(2-ethylhexyloxy)-5-methoxy-1,4-phenylenevinylene] (MEHPPV). Two different types of titanium dioxide were used, one synthesized using a sol-gel method, the other was a commercial paste. The crystal structure, porosity and absorption spectra of the titanium dioxide layers were measured, and the titanium dioxide synthesized using the sol-gel method had a much lower level of

Michelle J. Carey; Victor M. Burlakov; Bernard M. Henry; Kiril R. Kirov; Graham R. Webster; Hazel E. Assender; G. Andrew D. Briggs; Paul L. Burn; Chris R. Grovenor

2004-01-01

428

Mesoporous TiO2 single crystals delivering enhanced mobility and optoelectronic device performance.  

PubMed

Mesoporous ceramics and semiconductors enable low-cost solar power, solar fuel, (photo)catalyst and electrical energy storage technologies. State-of-the-art, printable high-surface-area electrodes are fabricated from thermally sintered pre-formed nanocrystals. Mesoporosity provides the desired highly accessible surfaces but many applications also demand long-range electronic connectivity and structural coherence. A mesoporous single-crystal (MSC) semiconductor can meet both criteria. Here we demonstrate a general synthetic method of growing semiconductor MSCs of anatase TiO2 based on seeded nucleation and growth inside a mesoporous template immersed in a dilute reaction solution. We show that both isolated MSCs and ensembles incorporated into films have substantially higher conductivities and electron mobilities than does nanocrystalline TiO2. Conventional nanocrystals, unlike MSCs, require in-film thermal sintering to reinforce electronic contact between particles, thus increasing fabrication cost, limiting the use of flexible substrates and precluding, for instance, multijunction solar cell processing. Using MSC films processed entirely below 150?°C, we have fabricated all-solid-state, low-temperature sensitized solar cells that have 7.3 per cent efficiency, the highest efficiency yet reported. These high-surface-area anatase single crystals will find application in many different technologies, and this generic synthetic strategy extends the possibility of mesoporous single-crystal growth to a range of functional ceramics and semiconductors. PMID:23467091

Crossland, Edward J W; Noel, Nakita; Sivaram, Varun; Leijtens, Tomas; Alexander-Webber, Jack A; Snaith, Henry J

2013-03-06

429

The preparation of highly ordered TiO2 nanotube arrays by an anodization method and their applications.  

PubMed

The tubular-shaped nanostructure of TiO(2) is very interesting, and highly ordered arrays of TiO(2) nanotubes (TNTs) can be easily fabricated by anodization of the Ti substrate in specific electrolytes. Here in this feature article, we review synthesis methods for various TNTs including normal, alloy, and architectural forms such as bamboos, lace, and flowers. Specific nanosize architectures such as bamboo and lace types can be regulated by alternating voltage and further anodizing. In order to extend light response of TNTs to visible solar spectra, various dopings of specific elements have been discussed. The normal and modified TNTs are suggested for applications such as dye sensitized solar cells, water splitting, photocatalytic degradation of pollutants, CO(2) reduction, sensors, energy storage devices including Li ion batteries and supercapacitors, and other applications such as flexible substrate and biomaterials. PMID:22634750

Jun, Yongseok; Park, Jong Hyeok; Kang, Man Gu

2012-05-28

430