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1

Optimum Nanoporous TiO2 Film and Its Application to Dye-sensitized Solar Cells  

Microsoft Academic Search

Properties of TiO2 nanoporous films, which are one of the crucial technologies in dye-sensitized solar cell, are investigated. The nanocrystalline TiO2 films were prepared with the sol-gel method at different pH in precursor and treatment temperature in autoclave for their application to dye-sensitized solar cells. The thickness of the TiO2 film is very important to the transfer of photoelectron as

Song-Yuan Dai; Kong-Jia Wang

2003-01-01

2

Dye Sensitized Solar Cells Using Freestanding TiO2 Nanotube Arrays  

NASA Astrophysics Data System (ADS)

A TiO2 photoanode was prepared by depositing TiO2 nanoparticle on the FTO glass followed by placing TiO2 nanotube arrays on the top of TiO2 nanoparticle film. The resulting TiO2 nanotube/nanoparticle photoanode was sensitized with N719 dye after TiCl4 treatment and exposure to O2 plasma. The resulting dye sensitized solar cell (DSSC) showed that the highest DSSC power conversion efficiency of 8.02% and 7.00% were yielded when a 20 ?m thick TiO2 nanoparticle and a 13/7 ?m TiO2 nanoparticle/nanotube were used as photoanode, respectively. The I˜V curve analysis suggested that the nanotubes had better electron transport pathway but lower electron generation. Future work will be focused on increasing the dye loading of nanotubes to improve the power conversion efficiency.

Xin, Xukai; Wang, Jun; Zhao, Lei; Lin, Zhiqun

2011-03-01

3

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

4

Electron transport and recombination in polycrystalline TiO2 nanowire dye-sensitized solar cells  

Microsoft Academic Search

Electron transport and recombination time constants in dye-sensitized solar cells made from TiO2 nanowires were determined using transient photocurrent and photovoltage measurements. The magnitude of the electron transport time (10?2 to 10?3 s) and its dependence on the illumination intensity were similar to those reported for dye-sensitized solar cells made from TiO2 nanoparticles indicating that electron capture and release by

Emil Enache-Pommer; Janice E. Boercker; Eray S. Aydil

2007-01-01

5

TiO2 nanotube arrays for quantum dots sensitized solar cells  

Microsoft Academic Search

Vertically oriented, highly ordered TiO2 nanotube arrays have attracted considerable attention because of their impressive competence in a variety of applications including solar cells, chemical sensing, photocatalysis and biomedical industry. However, only a few papers reported on the solar cells prepared by combining TiO2 nanotubes and semiconductor quantum dots (QDs) based on composite structures. This paper presents the preparation of

Xin Wen; Junchao Tao; Yingshui Sun; Yan Sun; Ning Dai

2009-01-01

6

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

7

Hybrid solar cells with ordered TiO 2 nanostructures and MEH-PPV  

Microsoft Academic Search

For use in hybrid solar cells consisting of TiO2 and poly[2-methoxy, 5-(2?-ethyl-hexyloxy)-1,4-phenylenevinylene] (MEH-PPV), a TiO2 nanostructure which has periodic hexagonal hole arrays was fabricated using surface relief gratings on azobenzene-functionalized polymer films as a template in the sol–gel reaction of a Ti-precusor. The ordered bulk heterojunction solar cells, prepared with the TiO2 nanostructure and MEH-PPV, have a higher power conversion

Seok-Soon Kim; Jang Jo; Chaemin Chun; Jae-Chul Hong; Dong-Yu Kim

2007-01-01

8

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

9

Influence of TiO 2\\/electrode interface on electron transport properties in back contact dye-sensitized solar cells  

Microsoft Academic Search

The influence of the TiO2\\/electrode interface was investigated on electron transport properties at the interface and in TiO2 porous film in back contact dye-sensitized solar cells. Analysis of dye-sensitized solar cells (DSCs) with Ti and TCO indicated that electron transport properties at TiO2\\/Ti and TiO2\\/TCO interfaces are similar despite the former's lack of a ‘built-in potential’. The dependence of short

Nobuhiro Fuke; Atsushi Fukui; Ashraful Islam; Ryoichi Komiya; Ryohsuke Yamanaka; Hiroshi Harima; Liyuan Han

2009-01-01

10

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

NASA Astrophysics Data System (ADS)

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

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

2013-12-01

11

Preparation of mesoporous nanocrystalline anatase TiO2 for dye sensitized solar cell application  

NASA Astrophysics Data System (ADS)

Dye sensitized solar cell (DSSC) introduced by Prof.M.Gratzel is a low cost alternative to the existing silicon based solar cells. Solar light conversion efficiency of the current DSSC can be further improved by replacing the conventional anatase TiO2 having lesser surface area with mesoporous high surface area anatase TiO2. This paper describes the sol-gel synthesis of mesoporous high surface area nanocrystalline anatase TiO2 by the controlled hydrolysis and condensation of titanium isopropoxide followed by heat treatment. XRD reveals that xerogel heat treated at 500°C is phase pure anatase. Crystallite size of prepared anatase TiO2 calculated using Scherrer equation was found to be 15 nm. BET analysis of prepared anatase TiO2 exhibited relatively high specific surface area of 97 m2/g, which is found to be almost double to that of the anatase TiO2 generally used for DSSC photo anode fabrication. The pore size distribution (BJH plot) also revealed the mesoporous nature of prepared anatase TiO2 having an average pore size of 7.4 nm.

Jacob, K. Stanly; Abraham, P. A.; Panicker, N. Rani; Pramanik, N. C.

2014-01-01

12

Water-soluble polythiophene\\/nanocrystalline TiO2 solar cells  

Microsoft Academic Search

We report the characteristics of polymer\\/nanocrystalline solar cells fabricated using an environmentally friendly water-soluble polythiophene and TiO2 in a bilayer configuration. The cells were made by dropping the polymer onto a TiO2 nanocrystalline film and then repeatedly sweeping a clean glass rod across the polymer as it dried. The devices showed an open circuit voltage of 0.81 V, a short

Qiquan Qiao; James T. McLeskey

2005-01-01

13

Formation of Tio2 Thin Film for Dye-Sensitized Solar Cell Application Using Electrophoresis Deposition  

NASA Astrophysics Data System (ADS)

One of important processes on the fabrication of dye-sensitized solar cell (DSSC) is formation of TiO2 thin film. Thickness of TiO2 thin film is needed to be controlled in order to obtain optimum TiO2 thickness. Electrophoresis deposition is simple method for thin film deposition which enable us to control the thickness of thin film. In this work, the formation of TiO2 thin film on indium-doped tin oxide (ITO) glass using electrophoresis deposition is numerically and experimentally studied. We have succeeded to control the thickness of TiO2 thin film by changing of electrophoresis applied voltage and deposition time. In the experiment, TiO2 particles were suspended into isopropyl alcohol solution. Mg(NO3)2 was added to the solution in order to obtain the stable solution for electrophoresis. We found numerically that the Mg(NO3)2 in the range from 10-6 M to 10-4 M, is appropriate condition for the electrophoresis deposition. Using this method, we have fabricated DSSC device and study the effect of TiO2 thickness on DSSCs characteristic. Our results shows that the electrophoresis is not only essential for DSSC application but also for the other devices with a given thickness of TiO2 film.

Nuryadi, Ratno; Akbar, Zico Alaia; Wargadipura, Agus Hadi S.; Gunlazuardi, Jarnuzi

2010-10-01

14

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

NASA Astrophysics Data System (ADS)

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

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

2012-03-01

15

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

PubMed

Hierarchical nanostructured titanium dioxide (TiO(2)) clumps were fabricated using electrostatic spray with subsequent nitrogen-ion doping by an ion-implantation technique for improvement of energy conversion efficiency for quantum dot-sensitized solar cells (QDSCs). CdSe quantum dots were directly assembled on the produced N-ion-implanted TiO(2) photoanodes by chemical bath deposition, and their photovoltaic performance was evaluated in a polysulfide electrolyte with a Pt counter electrode. We found that the photovoltaic performance of TiO(2) electrodes was improved by nearly 145% upon N-ion implantation. The efficiency improvement seems to be due to (1) the enhancement of electron transport through the TiO(2) layer by inter-particle necking of primary TiO(2) particles and (2) an increase in the recombination resistance at TiO(2)/QD/electrolyte interfaces by healing the surface states or managing the oxygen vacancies upon N-ion doping. Therefore, N-ion-doped photoanodes offer a viable pathway to develop more efficient QD or dye-sensitized solar cells. PMID:22371010

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

2012-04-01

16

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

NASA Astrophysics Data System (ADS)

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

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

2012-09-01

17

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

18

Research Update: Doping ZnO and TiO2 for solar cells  

NASA Astrophysics Data System (ADS)

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

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

2013-12-01

19

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

20

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

21

Anodic TiO 2 nanotubes powder and its application in dye-sensitized solar cells  

Microsoft Academic Search

An increasing energy demand and environmental pollution create a pressing need for clean and sustainable energy solutions.\\u000a TiO2 semiconductor material is expected to play an important role in helping solve the energy crisis through effective utilization\\u000a of solar energy based on photovoltaic devices. Dye-sensitized solar cells (DSSCs) are potentially lower cost alternative to\\u000a inorganic silicon-based photovoltaic cells. In this study,

Narges F. Fahim; Tohru Sekino

22

Anatase TiO2 nanotubes as photoanode for dye-sensitized solar cells.  

PubMed

To achieve higher power conversion efficiency of dye-sensitized solar cells, anatase TiO2 nanotubes anodized and transferred onto fluorine doped tin oxide glass. This technique is a promising candidate to improve the efficiency due to its outstanding properties, such as high light scattering effect, high surface-to-volume ratio, which result in enhancing light harvesting, minimum trapping sites, and low recombination rate. In this review, the structure, fabrication, and property of the TiO2 nanotube photoanode is compared with other photoanodes. In addition, the integration of a heterojunction and other advancements into the TiO2 nanotubes for getting better performance is also briefly discussed. PMID:24749414

Javed, Hafiz Muhammad Asif; Que, Wenxiu; He, Zuoli

2014-02-01

23

Preparation and Characterization of TiO2 Barrier Layers for Dye-Sensitized Solar Cells.  

PubMed

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

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

2014-07-01

24

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

25

Quasi-solid-state dye-sensitized solar cells employing nanocrystalline TiO 2 films made at low temperature  

Microsoft Academic Search

Quasi-solid-state dye-sensitized solar cells with enhanced performance were made by using nanocrystalline TiO2 films without any template deposited on plastic or glass substrates at low temperature. A simple and benign procedure was developed to synthesize the low-temperature TiO2 nanostructured films. According to this method, a small quantity of titanium isopropoxide (TTIP) was added in an ethanolic dispersion of TiO2 powder

Elias Stathatos; Yongjun Chen; Dionysios D. Dionysiou

2008-01-01

26

Preparation of TiO 2\\/Nano-metal composite particles and their applications in dye-sensitized solar cells  

Microsoft Academic Search

This study investigated the applicability of TiO2\\/Au (or TiO2\\/Ag) composite particles, which probably have the plasmon resonance effect, on FTO-glass (Fluorine doped tin oxide, SnO2:F) substrate of the working electrode of a dye-sensitized solar cell (DSSC). The dry particle coating technique was utilized to coat the surfaces of TiO2 particle with nano-sized Au (or Ag) powder particles. A layer of

Chuen-Shii Chou; Ru-Yuan Yang; Cheng-Kuo Yeh; You-Jen Lin

2009-01-01

27

Nanofibril Formation of Electrospun TiO2 Fibers and its Application to Dye?Sensitized Solar Cells  

Microsoft Academic Search

Electrospun TiO2 nanofibers were employed to the quasi?solid state dye?sensitized solar cells with porous electrodes, which enhanced the penetration of viscous polymer gel electrolytes. The morphology of electrospun TiO2 fibers was affected by the electrospinning parameters such as the types of polymers, the concentration of polymer and titanium(IV) propoxide (TiP), the ratio of TiP\\/PVAc. The TiO2 fibers electrospun from poly(vinyl

Seong Mu Jo; Mi Yeon Song; Young Rack Ahn; Chong Rae Park; Dong Young Kim

2005-01-01

28

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

2012-09-28

29

Annealing effect on Sb2S3-TiO2 nanostructures for solar cell applications  

PubMed Central

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.

2013-01-01

30

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

31

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

32

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

33

Electron transport in dye sensitized solar cells with TiO2\\/ZnO core-shell photoelectrode  

Microsoft Academic Search

This paper presents the electron transport in dye sensitized solar cell (DSSC) with TiO2\\/ZnO core-shell photoelectrode. Sol-gel processed ZnO was used to form the shell layer on TiO2 nanoparticles. DSSC with TiO2\\/ZnO core-shell photoelectrode resulted in 32 % enhancement in the overall photoconversion efficiency compared to DSSC with conventional TiO2 photoelectrode. Dark, illuminated current-voltage characteristics (I-V) and external quantum efficiency

Mariyappan Shanmugam; Braden Bills; Mahdi Farrokh Baroughi; David Galipeau

2010-01-01

34

Nanocrystalline TiO2/ZnO thin films: fabrication and application to dye-sensitized solar cells.  

PubMed

Nanocrystalline TiO2 thin films composed of densely packed grains were deposited onto indium-doped tin oxide (ITO)-coated glass substrates at room temperature using a chemical bath deposition technique. A layer-by-layer (LbL) process was utilized to obtain a 1.418-microm-thick TiO2/ZnO structure. The TiO2 surface was super-hydrophilic, but its hydrophilicity decreased considerably after ZnO deposition. Other TiO2/ZnO films were studied to assess their suitability as photoelectrodes in dye-sensitized solar cells (DSSCs). PMID:16375421

Mane, Rajaram S; Lee, Won Joo; Pathan, Habib M; Han, Sung-Hwan

2005-12-29

35

Quantitative electron tomography investigation of a TiO2 based solar cell photoanode  

NASA Astrophysics Data System (ADS)

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

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

2014-06-01

36

Mesoscopic CH3NH3PbI3/TiO2 heterojunction solar cells.  

PubMed

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

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

2012-10-24

37

Large-Sized Dye-Sensitized Solar Cells with TiO2 Cemented and Protected Silver Grids  

NASA Astrophysics Data System (ADS)

Large-sized dye-sensitized solar cells were prepared with TiO2 cemented and protected Ag grids in the photo and counter electrodes. The addition of high conductive TiO2 cemented Ag grids can maintain high performance with the enlargement of the cells. The preparation of the compact TiO2 layer on the Ag grids can prevent the corrosion of the electrolyte, moreover, when it is prepared on the whole area of the photo electrode, it also can play as the blocking layer for further enhancing the performance of cells. The presented method shows a simple and efficient way to prepare high performance large single cells.

Lan, Zhang; Wu, Jihuai; Lin, Jianming; Miaoliang

2012-03-01

38

Aggregated TiO2 Based Nanotubes for Dye Sensitized Solar Cells  

SciTech Connect

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

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

2013-11-01

39

Electron transport in dye-sensitized solar cells based on TiO2 nanowires  

NASA Astrophysics Data System (ADS)

Anatase titanium dioxide nanowire arrays were prepared by hydrothermally oxidizing titanium foils in aqueous alkali and transferred onto fluorinated tin oxide (FTO) glass for use as the photoanodes of front side illuminated dye-sensitized solar cells (DSCs). Electrochemical impedance spectroscopy (EIS) measurement was applied to compare the electron transport and recombination properties of DSCs using TiO2 nanowire films and TiO2 nanoparticle films as photoanodes. It was found that the nanowire array films possess smaller electron transport resistance ( R t) and larger electron diffusion length ( L e) in the photoanodes, suggesting that the nanowire arrays can enhance the electron transport rate and have a potential to improve the charge collection efficiency of DSCs.

Jiao, XingJian; Wang, Xiao; Li, Xin; Chen, HuiYuan; Wang, Gang; Li, JianBao; Lin, Hong

2014-05-01

40

Cation control of energetics on dye-sensitized nanocrystalline TiO2 for solar cells  

NASA Astrophysics Data System (ADS)

Regenerative solar cells based on nanocrystalline TiO2 (anatase) and the dye Ru(deeb)(bpy)2(PF6)2, where deeb is 4,4'-(CO2CH2CH3)2-2,2 '-bipyridine and bpy is 2,2'-bipyridine, have increased efficiency when in the presence of a high concentration of cations with a large charge-to-radius ratio. Concentration-dependent photoluminescence (PL) quenching and increased quantum yield for interfacial charge separation have been explored for mono- and divalent cations by absorbance, time-resolved and steady-state PL. Cation adsorption stabilizes TiO2 acceptor states resulting in energetically favorable electron transfer from the dye into the semiconductor conduction band. Quenching of the PL of excited states is reversible. A new luminescence approach for sensing alkali and alkaline earth metal cations utilizes the surface-adsorption/desorption induced energetic shifts of a semiconductor conduction band to alter the electron transfer quenching efficiency of a photoluminescent dye such as Ru(deeb)(bpy)2(PF 6)2 anchored to TiO2 nanoparticles. This approach yields intensity, lifetime, and wavelength-ratiometric calcium ion sensors that are sensitive to 5 x 10-4 M concentrations. In situ photoluminescence of a regenerative solar cell has been demonstrated as a probe of injection and efficiencies. The smaller the alkali cation, the higher the photocurrent and the more quenched the photoluminescence. The extent of quenching in 0.1 M iodide/0.01 M iodine electrolytes was 10-fold with LiI and 3-fold with NaI. A millimolar threshold concentration is observed for Li+ at which point a red shift in absorbance and photoluminescence spectra concomitant with significant static and dynamic quenching occurs. For Na+, the threshold concentration for observable red shift is more than an order of magnitude higher than for Li+. Cation adsorption was also observed on planar TiO2 surfaces in the absence of dye. The flat band potentials of single crystal TiO 2 (rutile) with cations in propylene carbonate and protons in H 2O were quantified by Mott-Schottky analysis of capacitance data. A difference of 230 mV is reported between extracted flat band potentials of Li+ and TBA+. The flat band potential for Li + is 150 mV more positive than for Na+. Nearly Nernstian behavior was observed on single crystal TiO2, with measured flat band shifts of 51 mV/pH unit, and on thermally oxidized titanium with shifts of 69 mV/pH unit.

Stux, Arnold M.

41

Effective antireflection coating based on TiO2-SiO2 mixture for solar cells  

NASA Astrophysics Data System (ADS)

A mixed alloy of TiO2 and SiO2 has been obtained using a 3-kW solar furnace. Films of the TiO2-SiO2 alloy applied onto a surface of glass and silicon plates exhibit high strength and adhesion, are transparent in the spectral range of sensitivity of solar cells, and can be used as effective antireflection coatings. It is established that adding TiO2 to SiO2 improves the optical properties of oxide coatings.

Suleimanov, S. Kh.; Dyskin, V. G.; Dzhanklych, M. U.; Kulagina, N. A.

2013-03-01

42

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

NASA Astrophysics Data System (ADS)

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

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

2008-03-01

43

Electrochemical study on the TiO2 porous electrodes for metal-free dye-sensitized solar cells  

NASA Astrophysics Data System (ADS)

Nanocrystalline TiO2 porous electrodes were prepared by screen-printing method in order to efficiently control the fabrication process. TiO2 viscous pastes were prepared from commercial TiO2 nano powder using ethyl cellulose as a porosity controlling agent. A metal-free organic dye (indoline dye D102) was used as a sensitizer. TiO2 porous electrodes with different thicknesses were investigated. The optical and physical properties of the TiO2 films, dye adsorption behavior and performance of dye-sensitized solar cells (DSCs) were investigated systemically. The electronic and ionic processes in DSCs were analysized and discussed by electrochemical impedance spectroscopy (EIS). High conversion efficiencies over 8.00 % under illumination of simulated AM1.5 sunlight (60mW/cm2) were achieved.

Zhang, D. W.; Chen, S.; Li, X. D.; Wang, Z. A.; Shi, J. H.; Sun, Z.; Yin, X. J.; Huang, S. M.

2009-08-01

44

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

PubMed Central

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

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

2013-01-01

45

Preparation and performance of dye-sensitized solar cells based on ZnO-modified TiO 2 electrodes  

Microsoft Academic Search

The ZnO-modified TiO2 electrode was prepared by adding Zn(CH3COO)2·2H2O to the TiO2 colloid during the sol-gel production process, and was used in dye-sensitized solar cells (DSCs). The open circuit voltage\\u000a (V\\u000a OC) and fill factor (ff) of the cells were improved significantly. The performances of the ZnO-modified TiO2 electrode such as dark current, transient photocurrent, impedance, absorption spectra, and flat

Sheng-Jun Li; Yuan Lin; Wei-Wei Tan; Jing-Bo Zhang; Xiao-Wen Zhou; Jin-Mao Chen; Zeng Chen

2010-01-01

46

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

PubMed

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

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

2010-11-01

47

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

NASA Astrophysics Data System (ADS)

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

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

2014-02-01

48

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

PubMed Central

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

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

2013-01-01

49

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

50

Rice grain-shaped TiO2 mesostructures by electrospinning for dye-sensitized solar cells.  

PubMed

Nanofibers, produced by electrospinning a solution containing titanium tetra(IV) isopropoxide, polyvinyl acetate and acetic acid in N,N-dimethyl acetamide, upon sintering at 500 °C produce rice grain-shaped TiO(2) mesostructures. Each rice grain-shaped TiO(2) has a mixed crystal structure and high porosity and the mesostructures are found to have applications in dye-sensitized solar cells. PMID:20820506

Nair, A Sreekumaran; Yang, Shengyuan; Zhu, Peining; Ramakrishna, Seeram

2010-10-21

51

Optical simulation of transmittance into a nanocrystalline anatase TiO 2 film for solar cell applications  

Microsoft Academic Search

Optical simulation has been employed, for the first time, for rigorous evaluation of transmittance into the TiO2 nanocrystalline film, entering from the fluorine-doped SnO2 (F-SnO2) coated glass side, in dye sensitized solar cells. The refractive index of the TiO2 film with various porosities was determined theoretically, and was in agreement with the data obtained by ellipsometric measurements. The simulation clearly

Yasuhiro Tachibana; Hitomi Y. Akiyama; Susumu Kuwabata

2007-01-01

52

A novel TiO2 tape for fabricating dye-sensitized solar cells on universal conductive substrates.  

PubMed

The present paper describes a new method for manufacturing large scale, stable, transportable, and designable nanostructured porous TiO2 tapes on various substrates for use in photoelectrochemical cells. The method involves predeposition of TiO2 strips on the fluorine doped tin oxide (FTO) glass by screen-printing method, peeling off TiO2 strips from the substrate by a novel laser-assisted lift-off technique, sintering the formed TiO2 tapes at 500 °C for 15 min, and compressing the sintered TiO2 tapes on different conductive substrates with a low pressure rolling press to form mechanically stable, electrically conducting, porous nanostructured TiO2 electrodes at room temperature. Photoelectrochemical characteristics of the resulted electrodes are presented. Dye-sensitized solar cells (DSSCs) with the as-fabricated TiO2 photoanodes on PET-ITO and FTO glass achieved a conversion efficiency of 4.2% and 6.2%, respectively. The potential use of this new manufacturing method in future DSSC applications is discussed. PMID:24289043

Shen, Jie; Cheng, Rui; Chen, Yiwei; Chen, Xiaohong; Sun, Zhuo; Huang, Sumei

2013-12-26

53

Influence of 1-methylbenzimidazole interactions with Li + and TiO 2 on the performance of dye-sensitized solar cells  

Microsoft Academic Search

In the present work, the effect and the mechanism of the interaction between 1-methylbenzimidazole (MBI) with Li+ and TiO2 on the performance of dye-sensitized solar cells were explored. A negative shift of the TiO2 Fermi level of the nanostructured TiO2 electrode could attribute to the interaction of MBI with Li+ and TiO2, which shown that MBI affects the surface state

Changneng Zhang; Jun Dai; Zhipeng Huo; Xu Pan; Linhua Hu; Fantai Kong; Yang Huang; Yifeng Sui; Xiaqin Fang; Kongjia Wang; Songyuan Dai

2008-01-01

54

A new architecture for solar cells involving a metal bridge deposited between active TiO2 particles  

NASA Astrophysics Data System (ADS)

The efficiency of titanium dioxide (TiO2)-based film solar cells fabricated by combined spray and electroplating methods was improved by forming metal bridges in the pores between TiO2 nanoparticles. The interfaces between TiO2 nanoparticles and metal bridges formed Schottky contacts, which minimized recombination of electron-hole pairs and increased electron transfer. A maximum efficiency of 4.38% was achieved for cells plated at 50 mA and 55 °C. This efficiency is higher than that reported for solar cells with a similar structure [Saehana et al., AIP Conf. Proc. 1284, 154 (2010); 1415, 163 (2011); IJBAS/IJENS 11, 15 (2011)]. We also identified that both current and temperature influence the morphology of the metal bridges and efficiency of the solar cell.

Saehana, Sahrul; Arifin, Pepen; Khairurrijal; Abdullah, Mikrajuddin

2012-06-01

55

Integration of TiO2 nanotube arrays into solid-state dye-sensitized solar cells  

NASA Astrophysics Data System (ADS)

In this investigation, transparent TiO2 nanotube arrays prepared on a FTO substrate are employed as 1D nanostructures providing elongated direct pathways for electron transport and collection in solid-state dye-sensitized solar cell (SDSC). Donor-antenna (D-A) dyes provide an exciting route for improving the light harvesting efficiency in dye sensitized solar cells owing to their high molar extinction coefficients and the effective spatial separation of charges in the charge-separated state. Hence in this study we fabricated SDSC devices with different thicknesses of transparent TiO2 nanotube array electrodes sensitized with Ru-(II)-donor-antenna dye and spiro-OMeTAD as a hole conductor. At AM 1.5 G, 100 mW/cm2 illumination intensity, a power conversion efficiency of 1.94% was achieved when the TiO2 nanotubes are initially subjected to TiCl4 treatment. Furthermore, a linear increase in the cell current without loss in fill factor is observed for increasing length of TiO2 nanotubes. The structural and morphological characteristics of the transparent TiO2 nanotube arrays as well as the optimal conditions for the fabrication of SDSCs with transparent TiO2 nanotubes on FTO glass are reported.

Bandara, J.; Shankar, K.; Basham, J.; Wietasch, H.; Paulose, M.; Varghese, O. K.; Grimes, C. A.; Thelakkat, M.

2011-02-01

56

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

57

TiO2 surface modification and characterization with nanosized PbS in dye-sensitized solar cells.  

PubMed

The nanoporous TiO2 films utilized in dye-sensitized solar cells (DSSCs) possess a large surface-to-volume ratio, which facilitates the adsorption of sensitizing dye and the recombination due to the high density of surface traps. In this paper, nanosized PbS was fabricated on the TiO2 films. The components of the modified TiO2 film were studied by X-ray diffraction (XRD) and electron probe microanalysis (EPMA), while the structure of the film was characterized with BET physisorption and high-resolution scanning electron microscopy (HRSEM). The results showed that the PbS particles were 2-3 nm and discrete on the surface of TiO2. Diffusion photovoltage (PV) spectroscopy was employed to study the charge separation and diffusion processes inside modified and unmodified TiO2 films. The diffusion PV signals revealed that the traps on the surface of TiO2 were extremely reduced due to the presence of PbS. The results of transient photovoltage and back I-V characteristics showed that the back reaction, that is, the recombination due to the reaction between an electron on TiO2 and the hole-transporting media, was retarded significantly. PMID:16854149

Wang, Peng; Wang, Liduo; Ma, Beibei; Li, Bin; Qiu, Yong

2006-07-27

58

TiO 2 films prepared by micro-plasma oxidation method for dye-sensitized solar cell  

Microsoft Academic Search

Nanocrystalline TiO2 films are widely investigated as the electrodes of dye-sensitized solar cell(s) with different preparation methods. In this paper, thin titanium dioxide films have been prepared on titanium plates by the micro-plasma oxidation method in the sulfuric acid solution. The thin TiO2 films were sensitized with a cis-RuL2(SCN)2·2H2O (L=cis-2,2?-bipyridine-4,4?-dicarboxylic acid) ruthenium complex and implemented into a dye-sensitized solar cell

Song Wang; Xiaohong Wu; Wei Qin; Zhaohua Jiang

2007-01-01

59

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

60

Synthesis of monodisperse colloidal TiO2 microspheres and performance of their dye-sensitized solar cells  

NASA Astrophysics Data System (ADS)

Monodisperse colloidal TiO2 microspheres with different size have been synthesized via controlled hydrolysis of tetrabutyltitanate (TBOT) in ethanol with addition of a salt solution. The photoelectric conversion performances of dye-sensitized solar cells (DSSCs) based on TiO2 microspheres were investigated. The results revealed that these TiO2 microspheres, which were well dispersed and uniform, and their size became gradually smaller with the increasing KCl concentration. The DSSC based on smaller TiO2 microspheres exhibited an enhanced photocurrent and conversion efficiency, which was attributed to its better absorption properties of dye molecules and superior conductivity. After the further optimization, the total conversion efficiency of DSSC with electrode 2 was 5.72%.

Zhu, Zhenfeng; Zhu, Chunkui; Liu, Hui; Wu, Yingfeng; Chen, Guanhong; Lv, Ting

2014-07-01

61

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

PubMed Central

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

2011-01-01

62

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

2011-01-01

63

TiO2 nanotubes infiltrated with nanoparticles for dye sensitized solar cells  

NASA Astrophysics Data System (ADS)

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

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

2011-06-01

64

Markedly Enhanced Performance of Dye Sensitized TiO2 Nanoparticle Solar Cells via Rational Surface Treatment  

NASA Astrophysics Data System (ADS)

Dye sensitized solar cell (DSSC) was fabricated with the P-25 TiO2 nanoparticle film sensitized with N719 dye. TiCl4 treatment was found to increase the power conversion efficiency of DSSC. More importantly, subsequent treatment with O2 plasma further enhanced the efficiency, while the O2 plasma processing of an untreated TiO2 photoanode resulted in a lower efficiency. With TiCl4 and O2 plasma treatments, dye sensitized TiO2 nanoparticle solar cell with 21 ?m thick active layer illuminated under 100 mW/cm^2 exhibited a markedly enhanced power conversion efficiency of 8.35% as compared to 3.86% for untreated cells.

Scheiner, Margaret; Xin, Xukai; Lin, Zhiqun

2011-03-01

65

Tri-layer antireflection coatings (SiO 2\\/SiO 2–TiO 2\\/TiO 2) for silicon solar cells using a sol–gel technique  

Microsoft Academic Search

Antireflection coatings (ARCs) have become one of the key issues for mass production of Si solar cells. They are generally performed by vacuum processes such as thermal evaporation, reactive sputtering, and plasma-enhanced chemical vapor deposition. In this work, a sol–gel method has been demonstrated to prepare the ARCs for the non-textured monocrystalline Si solar cells. The spin-coated TiO2 single-layer, SiO2\\/TiO2

Shui-Yang Lien; Dong-Sing Wuu; Wen-Chang Yeh; Jun-Chin Liu

2006-01-01

66

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

NASA Astrophysics Data System (ADS)

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

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

2012-12-01

67

Post-annealing of CdS/ZnS-assembled TiO2 films for photoelectrochemical solar cells  

NASA Astrophysics Data System (ADS)

CdS/ZnS-assembled TiO2 films are annealed at 350 °C in an inert Ar ambient before and after deposition of the ZnS overlayer and are denoted as the types I and II, respectively. As-grown and the annealed CdS-quantum-dot (QD)-assembled TiO2 samples without a ZnS overlayer were also prepared for comparison. Annealing of CdS-QD-assembled TiO2 without ZnS significantly reduced the electron lifetime due to the coalescence of CdS QDs on the TiO2 surface. The electron lifetime of the annealed CdS-QD-assembled TiO2 was recovered because of ZnS overlayer due to its being an intermediate layer and to the energy barrier effects at the TiO2/electrolyte and the CdS QD/electrolyte interfaces. The resultant photoelectrochemical solar cell (PEC) with the type I film exhibited better energy conversion efficiency than the PECs without the ZnS. The cell performance of the PEC with the type II film was further improved, as compared to that with the type I film. This can be attributed to the additional effect (improved interfacial contact at the CdS/ZnS interface) of the postannealing after the formation of the ZnS overlayer.

Jung, Sung Woo; Park, Min-Ah; Lee, Soo-Yong; Kim, Jae-Hong; Ahn, Kwang-Soon; Seo, Myeong-Soo; Kim, Hyunsoo; Choi, Chel-Jong; Kang, Soon-Hyung

2013-12-01

68

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

PubMed Central

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

2012-01-01

69

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

70

Structural Control of Hierarchically-Ordered TiO2 Films by Water for Dye-Sensitized Solar Cells.  

PubMed

A facile way of controlling the structure of TiO2 by changing the amount of water to improve the efficiency of dye-sensitized solar cells (DSSCs) is reported. Hierarchically ordered TiO2 films with high porosity and good interconnectivity are synthesized in a well-defined morphological confinement arising from a one-step self-assembly of preformed TiO2 (pre-TiO2 ) nanocrystals and a graft copolymer, namely poly(vinyl chloride)-g-poly(oxyethylene methacrylate). The polymer-solvent interactions in solution, which are tuned by the amount of water, are shown to be a decisive factor in determining TiO2 morphology and device performance. Systematic control of wall and pore size is achieved and enables the bifunctionality of excellent light scattering properties and easy electron transport through the film. These properties are characterized by reflectance spectroscopy, incident photon-to-electron conversion efficiency, and electrochemical impedance spectroscopy analyses. The TiO2 photoanode that is prepared with a higher water ratio, [pre-TiO2 ]:[H2 O]=1:0.3, shows a larger surface area, greater light scattering, and better electron transport, which result in a high efficiency (7.7?%) DSSC with a solid polymerized ionic liquid. This efficiency is much greater than that of commercially available TiO2 paste (4.0?%). PMID:24816729

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

2014-06-23

71

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

NASA Astrophysics Data System (ADS)

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

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

2007-04-01

72

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

PubMed

Semiconductor sensitized solar cell interfaces have been studied with photoelectron spectroscopy to understand the interfacial electronic structures. In particular, the experimental energy level alignment has been determined for complete TiO2/metal sulfide/polymer interfaces. For the metal sulfides CdS, Sb2S3 and Bi2S3 deposited from single source metal xanthate precursors, it was shown that both driving forces for electron injection into TiO2 and hole transfer to the polymer decrease for narrower bandgaps. The energy level alignment results were used in the discussion of the function of solar cells with the same metal sulfides as light absorbers. For example Sb2S3 showed the most favourable energy level alignment with 0.3 eV driving force for electron injection and 0.4 eV driving force for hole transfer and also the most efficient solar cells due to high photocurrent generation. The energy level alignment of the TiO2/Bi2S3 interface on the other hand showed no driving force for electron injection to TiO2, and the performance of the corresponding solar cell was very low. PMID:25007378

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

2014-08-28

73

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

74

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

75

Growth of nanocrystalline TiO2 films by pulsed-laser-induced liquid-deposition method and preliminary applications for dye-sensitized solar cells  

NASA Astrophysics Data System (ADS)

A novel technique, the pulsed-laser-induced liquid-deposition (PLLD) method, has been employed to grow nanocrystalline TiO2 films on fluorine-doped tin-oxide-coated (FTO) glass substrates at room temperature. The PLLD method was implemented by directing a pulsed laser into a liquid precursor and depositing the photosynthesized nanocrystalline TiO2 on an FTO glass substrate immersed in the liquid precursor. The as-grown nanocrystalline TiO2 films were found to have a rutile crystal structure and consist of a number of flower-like TiO2 crystal units arrayed together on the FTO glass substrate. Each of the flower-like TiO2 crystal units was composed of many nanostructured TiO2 whiskers, and their building blocks were found to be bundles of TiO2 nanorods with diameter of about 5 nm. The growth of these TiO2 nanorods is highly anisotropic, with the preferential growth direction along [001]. As-grown nanocrystalline TiO2 films were annealed at 450°C in air for 30 min for the applications of dye-sensitized solar cells, and the nanostructured characteristics with good porosity were preserved after annealing. A preliminary dye-sensitized solar cell was built based on the annealed nanocrystalline TiO2 film. The results suggest that the PLLD method is a promising technique for growing nanocrystalline TiO2 films for photovoltaic applications.

Wang, Guo-Bing; Fu, Min-Gong; Lu, Bin; Du, Guo-Ping; Li, Li; Qin, Xiao-Mei; Shi, Wang-Zhou

2010-09-01

76

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

77

Spray deposition and compression of TiO 2 nanoparticle films for dye-sensitized solar cells on plastic substrates  

Microsoft Academic Search

Spray deposition of powder suspensions followed by room temperature compression was studied as a method for preparing nanostructured TiO2 films for dye-sensitized solar cells. The structure of the films was analyzed with optical and scanning electron microscopy and the films were applied to dye-sensitized solar cells. Continuous and fast deposition of crack-free 7–14?m thick films was achieved by heating the

Janne Halme; Jaakko Saarinen; Peter Lund

2006-01-01

78

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

Microsoft Academic Search

We present the synthesis, electrochemical properties and device-based investigation of triphenylene diamine (TPD) sensitizer with an extended ? system consisting of donor, electron conducting and anchoring group for solid-state dye-sensitized solar cells. Solid-state dye-sensitized solar cells were fabricated using blocking TiO2 electrodes, nanoporous TiO2 electrodes and the organic hole-transporting medium, HTM (spiro-OMeTAD) in a fluorine doped tin oxide\\/blocking TiO2\\/nanoporous TiO2\\/TPDs\\/hole

Sule Erten-Ela; Johannes Brendel; Mukundan Thelakkat

2011-01-01

79

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

PubMed

Quantum dot-sensitized solar cells based on Zn-doped TiO(2) (Zn-TiO(2)) film photoanode and polysulfide electrolyte were fabricated. Zn-TiO(2) nanoparticles were obtained via a hydrothermal method and screen printed on the fluorine-doped tin oxide glass to prepare the photoanode. The structure, morphology and impedance of the Zn-TiO(2)/CdS film and the photovoltaic performance of the Zn-TiO(2)/CdS cell were investigated. It was found that the photovoltaic efficiency was improved by 24% when the Zn-TiO(2) film was adopted as the photoanode of CdS QDSSCs instead of only the TiO(2) layer. The improvement was ascribed to the reduction of electron recombination and the enhancement of electron transport in the TiO(2) film by Zn doping. PMID:20648354

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

2010-07-01

80

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

PubMed Central

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

2013-01-01

81

Low-Temperature Fabrication of Dye-Sensitized Solar Cells Using Pre-Sintered TiO2 Aggregates  

NASA Astrophysics Data System (ADS)

The low-temperature fabrication of photoelectrodes for flexible dye-sensitized solar cells was investigated using aggregates of TiO2 nanoparticles. These aggregates were prepared by grinding mesoporous TiO2 bulk ceramics, and the deposited films almost retained the mesoporous structures of the original ceramics. Photoelectrodes fabricated with the aggregates exhibited a short-circuit current density comparable to that for the high-temperature sintered films, when the film thickness was up to 4 ?m. In thicker films, however, the current values did not increase with thickness. The electron diffusion length evaluated from steady-state measurements was much smaller than the value obtained for the high-temperature sintered films, implying the degradation of interparticle connection during the preparation of aggregates. It was also found that TiO2 submicron crystals incorporated into the photoelectrodes effectively improved the electron diffusion length as well as the light absorption coefficient.

Yasuda, Takashi; Yukita, Masafumi; Furukawa, Shoji

2013-05-01

82

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

2012-03-01

83

Organic solvent based TiO 2 dispersion paste for dye-sensitized solar cells prepared by industrial production level procedure  

Microsoft Academic Search

In order to prepare the TiO2 liquid dispersions for the electrodes of dye-sensitized solar cells with industrial mass production level at a reasonable\\u000a cost, the present study investigates the preparation of TiO2 liquid dispersions by a general industrial dispersion technique using readily available P25. To determine the TiO2 dispersion offering the best light–electricity energy conversion efficiency, the suitability of various

Ryohei Mori; Tsutomu Ueta; Kazuo Sakai; Yasuhiro Niida; Yasuko Koshiba; Li Lei; Katsuhiko Nakamae; Yasukiyo Ueda

2011-01-01

84

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

85

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

PubMed

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

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

2012-01-01

86

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

NASA Astrophysics Data System (ADS)

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

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

2014-01-01

87

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

Microsoft Academic Search

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

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

2004-01-01

88

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

89

3-D TiO2 nanoparticle/ITO nanowire nanocomposite antenna for efficient charge collection in solid state dye-sensitized solar cells  

NASA Astrophysics Data System (ADS)

TiO2 nanoparticle (NP)/ITO nanowire (NW) nanocomposites for use as photoelectrode materials were fabricated to improve the charge collection efficiency in solid state dye sensitized solar cells (ss-DSSCs). The average current density for ss-DSSCs containing TiO2 NP/ITO NW arrays was 7.2 mA cm-2 that was 98% higher than that for the conventional TiO2 NP ss-DSSCs. The intensity modulated photocurrent spectroscopy (IMPS) and intensity modulated photovoltage spectroscopy (IMVS) studies exhibited that the electron diffusion length of TiO2 NP/ITO-NW nanocomposite ss-DSSCs was in the range of 4.3-5.6 ?m, longer than that of TiO2 NP solar cells (2.6-4.1 ?m). The longer diffusion length was responsible for the boosted current densities of TiO2 NP/ITO NW nanocomposite ss-DSSCs. We also employed the TiO2 NP/ITO NW nanocomposite photoelectrode to inorganic-organic perovskite solar cells whose energy conversion efficiency was 7.5%.TiO2 nanoparticle (NP)/ITO nanowire (NW) nanocomposites for use as photoelectrode materials were fabricated to improve the charge collection efficiency in solid state dye sensitized solar cells (ss-DSSCs). The average current density for ss-DSSCs containing TiO2 NP/ITO NW arrays was 7.2 mA cm-2 that was 98% higher than that for the conventional TiO2 NP ss-DSSCs. The intensity modulated photocurrent spectroscopy (IMPS) and intensity modulated photovoltage spectroscopy (IMVS) studies exhibited that the electron diffusion length of TiO2 NP/ITO-NW nanocomposite ss-DSSCs was in the range of 4.3-5.6 ?m, longer than that of TiO2 NP solar cells (2.6-4.1 ?m). The longer diffusion length was responsible for the boosted current densities of TiO2 NP/ITO NW nanocomposite ss-DSSCs. We also employed the TiO2 NP/ITO NW nanocomposite photoelectrode to inorganic-organic perovskite solar cells whose energy conversion efficiency was 7.5%. Electronic supplementary information (ESI) available: SEM images of a 3-D TiO2 nanoparticle (NP)/ITO nanowire (NW) nanocomposite photoelectrode, photovoltaic properties, J-V curves for the best performance cells, and the plot of dye loading vs. active layer thickness. See DOI: 10.1039/c4nr00621f

Han, Gill Sang; Lee, Sangwook; Noh, Jun Hong; Chung, Hyun Suk; Park, Jong Hoon; Swain, Bhabani Sankar; Im, Jeong-Hyeok; Park, Nam-Gyu; Jung, Hyun Suk

2014-05-01

90

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

PubMed Central

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

2013-01-01

91

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

PubMed

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

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

2013-11-01

92

Nanoparticle self-assembled hollow TiO2 spheres with well matching visible light scattering for high performance dye-sensitized solar cells.  

PubMed

Submicrometer-sized hollow TiO(2) spheres are directly self-assembled from TiO(2) nanoparticles without using any template or surfactant as a scattering layer for dye-sensitized solar cells, showing good visible light scattering match to significantly improve the photoconversion efficiency. PMID:22836665

Pang, Hongchang; Yang, Hongbin; Guo, Chun Xian; Lu, Jinlin; Li, Chang Ming

2012-09-11

93

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

NASA Astrophysics Data System (ADS)

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

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

1999-10-01

94

Functions of Self-Assembled Ultrafine TiO2 Nanocrystals for High Efficient Dye-Sensitized Solar Cells.  

PubMed

In this paper, we demonstrate a simple approach of self-assembled process to form a very smooth and compacted TiO2 underlayer film from ultrafine titanium oxide (TiO2) nanocrystals with dimension of 4 nm for improving the electrical properties and device performances of dye-sensitized solar cells (DSSCs). Because the TiO2 film self-assembles by simply casting the TiO2 on fluorine-doped tin oxide (FTO) substrate, it can save a lot of materials in the process. As compared with control DSSC without the self-assembled TiO2 (SA-TiO2) layer, short-circuit current density (Jsc) improves from 14.9 mA/cm(2) for control DSSC to 17.3 mA/cm(2) for masked DSSC with the SA-TiO2 layer. With the very smooth SA-TiO2 layer, the power conversion efficiency is enhanced from 8.22% (control) to 9.35% for the DSSCs with mask and from 9.79% (control) to 11.87% for the DSSCs without mask. To explain the improvement, we have studied the optical properties, morphology, and workfunction of the SA-TiO2 layer on FTO substrate as well as the impedance spectrum of DSSCs. Importantly, we find that the SA-TiO2 layers have better morphology, uniformity, and contact with FTO electrode, increased workfunction and optical transmission, as well as reduced charge recombination at the contact of FTO substrate contributing to the improved device performances. Consequently, our results show that the simple self-assembly of TiO2 ultrafine nanocrystals forms a very good electron extraction layer with both improved optical and electrical properties for enhancing performances of DSSCs. PMID:24665885

Xie, Fengxian; Cherng, Sheng-Jye; Lu, Shunmian; Chang, Ya-Huei; Sha, Wei E I; Feng, Shien-Ping; Chen, Chih-Ming; Choy, Wallace C H

2014-04-23

95

Photochemical solar cells based on dye-sensitization of nanocrystalline TiO2  

Microsoft Academic Search

A new type of photovoltaic cell is described. It is a photoelectrochemical device that is based on the dye sensitization of thin (10-30 mum) films of TiO2 nanoparticles in contact with a non-aqueous liquid electrolyte. The cell is very simple to fabricate and, in principle, its color can be tuned through the visible spectrum, ranging from being completely transparent to

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

1997-01-01

96

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

97

Importance of binding states between photosensitizing molecules and the TiO 2 surface for efficiency in a dye-sensitized solar cell  

Microsoft Academic Search

The construction of dye-sensitized TiO2 solar cells is studied using a ruthenium complex, cis-di(thiocyanato)-N,N?-bis(2,2?-bipyridyl-4,4?-dicar?ylic acid)-ruthenium (II), as a photosensitizing molecule (dye) on TiO2 nanocrystallite films to determine the interfacial binding effect on photoenergy conversion efficiency. Photoconversion efficiency is improved by electrochemical treatment of TiO2 films, or reflux treatment for effective anchoring of the photosensitizing molecules on TiO2 nanocrystallite films. Characteristics

Kei Murakoshi; Gentaro Kano; Yuji Wada; Shozo Yanagida; Hiromitsu Miyazaki; Masamitsu Matsumoto; Sadao Murasawa

1995-01-01

98

Electrophoretically deposited TiO 2 photo-electrodes for use in flexible dye-sensitized solar cells  

Microsoft Academic Search

The preparation of an electrophoretically deposited film composed of wide band gap nanocrystalline TiO2 without the use of a surfactant or any post-thermal treatments is described. The resulting film was examined with reference to applications in a flexible dye-sensitized solar cell. The packing densities of the films could be controlled through electrophoretic deposition parameters, such as the applied electric field

Jun-Ho Yum; Seok-Soon Kim; Dong-Yu Kim; Yung-Eun Sung

2005-01-01

99

Application of TiO 2 nano-particles on the electrode of dye-sensitized solar cells  

Microsoft Academic Search

In this study, nano-TiO2 thin film electrode and solar cell have been investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), ultraviolet–visible absorption spectra, contact angle, X-ray photoelectron spectroscopy (XPS), and current–voltage characteristics analyses. X-ray diffraction patterns show that the best sintering temperature of a nano-TiO2 film is 600°C, at which TiO2 anatase phase forms best and the particle size

T. H. Meen; W. Water; W. R. Chen; S. M. Chao; L. W. Ji; C. J. Huang

2009-01-01

100

Preparation of TiO 2 films by layer-by-layer assembly and their application in solar cell  

Microsoft Academic Search

Polyacrylate sodium (PAAS)\\/titania (TiO2) multilayers have been fabricated through the electrostatic layer-by-layer assembly technique. The composite films display an excellent photovoltaic performance after sintering and sensitization by cyanine dye (CD), which can be applied in dye-sensitized solar cells. The properties of PAAS\\/TiO2 multilayers are investigated by ultraviolet–visible spectroscopy (UV–vis), X-ray photoelectron spectroscopy (XPS), X-ray diffraction analysis (XRD), Thermogravimetric analysis (TGA),

L. Zhang; A. J. Xie; Y. H. Shen; S. K. Li

2010-01-01

101

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

Microsoft Academic Search

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

Radin Ahmadian

2010-01-01

102

Enhanced photovoltaic properties of overlayer-coated nanocrystalline TiO 2 dye-sensitized solar cells (DSSCs)  

Microsoft Academic Search

TiO2 dye-sensitized solar cells (DSSCs) coated with various oxide layers were fabricated via a screen printing method and the\\u000a effects of the oxide layers on the photovoltaic properties were systematically investigated. The open circuit voltage (V\\u000a oc) was closely dependent to the conduction band (CB) edge position and the band gap energy (E\\u000a g) of the oxide layers, while the

Jin Young Kim; Sangwook Lee; Jun Hong Noh; Hyun Suk Jung; Kug Sun Hong

2009-01-01

103

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

104

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

PubMed

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

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

2014-01-22

105

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

106

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

NASA Astrophysics Data System (ADS)

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

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

2013-04-01

107

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

NASA Astrophysics Data System (ADS)

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

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

2013-11-01

108

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

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

109

Dye sensitized solar cells (DSSCs) based on modified iron phthalocyanine nanostructured TiO 2 electrode and PEDOT:PSS counter electrode  

Microsoft Academic Search

An iron phthalocyanine with tetra-sulphonated substituents (FeTsPc) was used as photosentizer for the development of dye sensitized nanostructured TiO2 solar cells. The influence of surface modification (TiO2 film treated with HCl and HNO3) and thermal annealing of TiO2 photo-electrode on the performance of dye sensitized solar cell (DSSC) having structure FTO\\/TiO2–FeTsPc\\/electrolyte\\/PEDOT:PSS (carbon added)\\/FTO was investigated through the analysis of current–voltage

P. Balraju; Manish Kumar; M. S. Roy; G. D. Sharma

2009-01-01

110

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

PubMed

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

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

2014-02-01

111

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

PubMed

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

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

2014-01-01

112

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

PubMed Central

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

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

2014-01-01

113

Defect states in hybrid solar cells consisting of Sb2S3 quantum dots and TiO2 nanoparticles  

NASA Astrophysics Data System (ADS)

We have studied defect states in an organic-inorganic hybrid solar cell containing Sb2S3 quantum dots (QDs) and TiO2 nanoparticles (NPs) by using deep level transient spectroscopy (DLTS). An Au electrode was deposited as a Schottky contact on the sample, where the Sb2S3 QDs were distributed on the surface of TiO2 NPs by chemical synthesis. The activation energy and capture-cross section of an interface state between the Sb2S3 QDs and the TiO2 NPs were found to be about 0.78 eV and 2.21 × 10-9 cm-2, respectively. Also, the densities of this interface trap under a measurement voltage of -1 V were approximately 2.5 × 1017 cm-3. Based on these results, the interface trap was positioned around Ec - 1.03 eV below the conduction band edge of Sb2S3 QD. Thus, the external quantum efficiency of the solar cell was affected because of its role as a recombination center for carriers generated from Sb2S3 QDs.

Lee, Dong Uk; Woo Pak, Sang; Gook Cho, Seong; Kyu Kim, Eun; Il Seok, Sang

2013-07-01

114

Preparation of nanoporous MgO-coated TiO2 nanoparticles and their application to the electrode of dye-sensitized solar cells.  

PubMed

Sol-gel-derived Mg(OH)(2) gel was coated onto TiO(2) nanoparticles, and the subsequent thermal topotactic decomposition of the gel formed a highly nanoporous MgO crystalline coating. The specific surface area of the electrode that was prepared from the core-shell-structured TiO(2) nanoparticles significantly increased compared with that of the uncoated TiO(2) electrode. The increase in the specific surface area of the MgO-coated TiO(2) electrode was attributed to the highly nanoporous MgO coating layer that resulted from the topotactic reaction. Dye adsorption behavior and solar cell performance were significantly enhanced by employing the MgO-coated TiO(2) electrode. Optimized coating of a MgO layer on TiO(2) nanoparticles enhanced the energy conversion efficiency as much as 45% compared to that of the uncoated TiO(2) electrode. This indicates that controlling the extrinsic parameters such as the specific surface area is very important to improve the energy conversion efficiency of TiO(2)-based solar cells. PMID:16262288

Jung, Hyun Suk; Lee, Jung-Kun; Nastasi, Michael; Lee, Sang-Wook; Kim, Jin-Young; Park, Jong-Sung; Hong, Kug Sun; Shin, Hyunho

2005-11-01

115

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

116

3-D TiO2 nanoparticle/ITO nanowire nanocomposite antenna for efficient charge collection in solid state dye-sensitized solar cells.  

PubMed

TiO2 nanoparticle (NP)/ITO nanowire (NW) nanocomposites for use as photoelectrode materials were fabricated to improve the charge collection efficiency in solid state dye sensitized solar cells (ss-DSSCs). The average current density for ss-DSSCs containing TiO2 NP/ITO NW arrays was 7.2 mA cm(-2) that was 98% higher than that for the conventional TiO2 NP ss-DSSCs. The intensity modulated photocurrent spectroscopy (IMPS) and intensity modulated photovoltage spectroscopy (IMVS) studies exhibited that the electron diffusion length of TiO2 NP/ITO-NW nanocomposite ss-DSSCs was in the range of 4.3-5.6 ?m, longer than that of TiO2 NP solar cells (2.6-4.1 ?m). The longer diffusion length was responsible for the boosted current densities of TiO2 NP/ITO NW nanocomposite ss-DSSCs. We also employed the TiO2 NP/ITO NW nanocomposite photoelectrode to inorganic-organic perovskite solar cells whose energy conversion efficiency was 7.5%. PMID:24788946

Han, Gill Sang; Lee, Sangwook; Noh, Jun Hong; Chung, Hyun Suk; Park, Jong Hoon; Swain, Bhabani Sankar; Im, Jeong-Hyeok; Park, Nam-Gyu; Jung, Hyun Suk

2014-06-01

117

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

118

Improved performance in dye-sensitized solar cells employing TiO2 photoelectrodes coated with metal hydroxides.  

PubMed

The performance of dye-sensitized solar cells (DSCs) was compared before and after processing the TiO(2) electrodes by minute-order electrochemical reactions with metal nitrates, where the metals were Mg, Zn, Al, and La, in 2-propanol. An overcoating of metal hydroxide was formed without the need for a sintering process, and magnesium hydroxide was found to give the largest improvement in photovoltage, fill factor, and eventually overall conversion efficiency of the DSCs. To analyze the nature of the improvement, the diffusion coefficient (D) and electron lifetime (tau) were determined. While little influence of overcoating on D was seen, a correlation between the increase in tau and V(oc) was observed for the metals examined here. The remarkable improvement in the electron lifetime of the DSCs suggests that an overcoating with magnesium hydroxide species function as the blocking layers at the fluorine-doped tin oxide and TiO(2) interfaces, thus contributing to the suppression of electron leakage, i.e., recombination processes between unidirectional transporting electrons and poly-iodides such as tri-iodide in the processed TiO(2) photoelectrode systems. The increase in V(oc) can be explained by the increased electron density caused by the increase in electron lifetime. PMID:16494331

Yum, Jun-Ho; Nakade, Shogo; Kim, Dong-Yu; Yanagida, Shozo

2006-02-23

119

The function of a TiO2 compact layer in dye-sensitized solar cells incorporating "planar" organic dyes.  

PubMed

We present a device based study into the operation of liquid electrolyte dye-sensitized solar cells (DSSC's) using organic dyes. We find that, for these systems, it is entirely necessary to employ a compact TiO2 layer between the transparent fluorine doped SnO2 (FTO) anode and the electrolyte in order to reduce charge recombination losses. By incorporation of a compact layer, the device efficiency can be increased by over 160% under simulated full sun illumination and more than doubled at lower light intensities. This is strong evidence that the more widely employed ruthenium based sensitizers act as to "insulate" the anode against recombination losses and that many planar organic dyes employed in DSSC's could greatly benefit from the use of a compact TiO2 blocking layer. This is in strong contrast to DSSC's sensitized with ruthenium based systems, where the introduction of compact TiO2 has only marginal effects on conversion efficiencies. PMID:18318506

Burke, Anthony; Ito, Seigo; Snaith, Henry; Bach, Udo; Kwiatkowski, Joe; Grätzel, Michael

2008-04-01

120

A novel preparation of small TiO2 nanoparticle and its application to dye-sensitized solar cells with binder-free paste at low temperature  

NASA Astrophysics Data System (ADS)

TiO2 nanoparticles with diameter <10 nm were synthesized by a facile, non-hydrothermal method at low temperature. A porous TiO2 film electrode consisting of the obtained small TiO2 nanoparticles and commercial TiO2 nanoparticles without any organic binder was prepared at low temperature. The photovoltaic performance of the solar cell based on the TiO2 electrode was investigated by the current-voltage and electrochemical impedance spectra. All the experimental results indicate that the addition amount of the small TiO2 nanoparticles in the binder-free paste affects the photovoltaic performance of the photoelectrode greatly. The overall energy conversion efficiency of the optimized binder-free photoelectrode achieves 3.53% without high-temperature sintering. Additionally, the performance of the small particles derived from this facile method can be comparable with that of small ones obtained from traditionally hydrothermal method, indicating the small particles in our study can be applied to flexible dye-sensitized solar cells. And the present low-temperature preparation of photoelectrode containing small TiO2 nanoparticles shows an encouraging performance on both conductive glass and plastic substrates and could be suited in the industrial and large-scale application due to its low energy cost and relatively high conversion efficiency.

Fan, Ke; Gong, Chuqing; Peng, Tianyou; Chen, Junnian; Xia, Jiangbin

2011-09-01

121

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

122

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

123

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

124

Panchromatic response composed of hybrid visible-light absorbing polymers and near-IR absorbing dyes for nanocrystalline TiO 2-based solid-state solar cells  

Microsoft Academic Search

In pursuit of panchromatic sensitizers for mesoporous TiO2-based solid-state solar cells, a near-IR absorbing zinc phthalocyanine dye (coded TT1) was firstly adsorbed over relatively thin (?1?m) TiO2 mesoporous films and then a visible-light absorbing polymer [regioregular poly(3-hexylthiophene), P3HT] was incorporated into the mesopores as both a second sensitizer and a solid hole conductor. After optimizing some experimental parameters, these hybrid

Hyo Joong Lee; Henry C. Leventis; Saif A. Haque; Tomas Torres; Michael Grätzel

2011-01-01

125

Effective enhancement of the performance of black dye based dye-sensitized solar cells by metal oxide surface modification of the TiO2 photoelectrode.  

PubMed

Effective enhancement of the performance of black dye based dye-sensitized solar cells has been achieved by MgO or Al(2)O(3) surface modification of the TiO(2) photoelectrode. The conversion efficiency was improved from 10.4% to 10.8% due to the blocking effect of the thin overlayer at the TiO(2) surface. PMID:22473216

Ozawa, Hironobu; Okuyama, Yu; Arakawa, Hironori

2012-05-01

126

Enhancement in dye-sensitized solar cells based on MgO-coated TiO2 electrodes by reactive DC magnetron sputtering  

Microsoft Academic Search

A surface modification method was carried out by reactive DC magnetron sputtering to fabricate TiO2 electrodes coated with insulating MgO for dye-sensitized solar cells. The MgO-coated TiO2 electrode had been characterized by x-ray photoelectron spectroscopy (XPS), energy-dispersive x-ray spectroscopy (EDX), scanning electron microscopy (SEM), UV-vis spectrophotometer, cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The study results revealed that the

Sujuan Wu; Hongwei Han; Qidong Tai; Jing Zhang; Sheng Xu; Conghua Zhou; Ying Yang; Hao Hu; Bo Lei Chen; Bobby Sebo; Xing-Zhong Zhao

2008-01-01

127

Applications of vertically oriented TiO 2 micro-pillars array on the electrode of dye-sensitized solar cell  

Microsoft Academic Search

In this research, dye-sensitized solar cells based on TiO2 micro-pillars fabricated by inductive couple plasma etcher were investigated by analyses of X-ray diffraction (XRD), scanning electron microscopy (SEM), contact angle, ultraviolet-visible absorption spectra (UV–vis), and current–voltage characteristics. X-ray diffraction patterns show that the TiO2 anatase phase forms while sintering at 450°C for 30min. The SEM images reveal that the diameter

T. H. Meen; C. J. Huang; S. M. Chao; J. K. Tsai; W. Water; W. R. Chen; Y. S. Liu; L. W. Ji

2011-01-01

128

Room temperature deposition of TiO 2 using nano particle deposition system (NPDS): Application to dye-sensitized solar cell (DSSC)  

Microsoft Academic Search

To apply for the working electrode of dye-sensitized solar cell (DSSC), semiconducting TiO2 powder is deposited on indium tin oxide (ITO)-coated glass. In conventional DSSC fabrication, the high-temperature sintering\\u000a process should be contained to make the necking of powders, and to assemble powders and substrate. In this research, dry TiO2 powder is deposited using a nano particle deposition system (NPDS)

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

2011-01-01

129

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

130

Mn-doped CdS quantum dots sensitized hierarchical TiO2 flower-rod for solar cell application  

NASA Astrophysics Data System (ADS)

A double-layered TiO2 film which three dimensional (3D) flowers grown on highly ordered self-assembled one dimensional (1D) TiO2 nanorods was synthesized directly on transparent fluorine-doped tin oxide (FTO) conducting glass substrate by a facile hydrothermal method and was applied as photoanode in Mn-doped CdS quantum dots sensitized solar cells (QDSSCs). The 3D TiO2 flowers with the increased surface areas can adsorb more QDs, which increased the absorption of light; meanwhile 1D TiO2 nanorods beneath the flowers offered a direct electrical pathway for photogenerated electrons, accelerating the electron transfer rate. A typical type II band alignment which can effectively separate photogenerated excitons and reduce recombination of electrons and holes was constructed by Mn-doped CdS QDs and TiO2 flower-rod. The incident photon-to-current conversion efficiency (IPCE) of the Mn-doped CdS/TiO2 flower-rod solar cell reached to 40% with the polysulfide electrolyte filled in the solar cell. The power conversion efficiency (PCE) of 1.09% was obtained with the Mn-doped CdS/TiO2 flower-rod solar cell under one sun illumination (AM 1.5G, 100 mW/cm2), which is 105.7% higher than that of the CdS/TiO2 nanorod solar cell (0.53%).

Yu, Libo; Li, Zhen; Liu, Yingbo; Cheng, Fa; Sun, Shuqing

2014-06-01

131

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

PubMed

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

Andrei, Codrin; Zerulla, Dominic

2013-01-01

132

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

PubMed Central

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

Andrei, Codrin; Zerulla, Dominic

2013-01-01

133

Enhanced performance of a dye-sensitized solar cell with the incorporation of titanium carbide in the TiO2 matrix.  

PubMed

The effects of incorporation of various weight percentages of titanium carbide (TiC) into TiO(2) matrices on the photovoltaics of the respective dye-sensitized solar cells (DSSCs) were investigated. It is established through relevant photographs, XRD and EDX analysis that TiC was partially converted into anatase TiO(2) (a-TiO(2)) when the TiC was sintered at 450 degrees C. With the incorporation of 3.0 wt% of the TiC in the TiO(2) film, the solar-to-electricity conversion efficiency (eta) of the cell reached 7.56% from its value of 6.61% with a bare TiO(2) film. "In situ" incorporation of this TiC/a-TiO(2) composite in the commercial TiO(2) is considered as the basis for enhanced cell efficiency of the benefited cell. The variations in J(SC), FF, and V(OC) are explained by analyzing the data of dark currents, UV-absorption spectra, transparency spectra, and electrochemical impedance spectra (EIS) which were obtained under illumination and darkness. Enhancement in the V(OC) for the promoted cell is explained through pertinent electron lifetime in the TiO(2) film, which was obtained by using laser-induced photo-voltage transient studies. Electron diffusion coefficient was also measured by using laser-induced photo-current transient studies. PMID:20571617

Lee, Chuan-Pei; Chen, Po-Yen; Vittal, R; Ho, Kuo-Chuan

2010-08-28

134

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

135

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

136

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

PubMed

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

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

2014-06-01

137

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

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

138

Simply synthesized TiO2 nanorods as an effective scattering layer for quantum dot sensitized solar cells  

NASA Astrophysics Data System (ADS)

TiO2 nanorod layers are synthesized by simple chemical oxidation of Ti substrates. Diffuse reflectance spectroscopy measurements show effective light scattering properties originating from nanorods with length scales on the order of one micron. The films are sensitized with CdSe quantum dots (QDs) by successive ionic layer adsorption and reaction (SILAR) and integrated as a photoanode in quantum dot sensitized solar cells (QDSCs). Incorporating nanorods in photoanode structures provided 4- to 8-fold enhancement in light scattering, which leads to a high power conversion efficiency, 3.03% (Voc = 497 mV, Jsc = 11.32 mA/cm2, FF = 0.54), in optimized structures. High efficiency can be obtained just by tuning the photoanode structure without further treatments, which will make this system a promising nanostructure for efficient quantum dot sensitized solar cells.

Mahmoud, Samadpour; Azam Iraji, zad; Mehdi, Molaei

2014-04-01

139

Enhancement in dye-sensitized solar cells based on MgO-coated TiO2 electrodes by reactive DC magnetron sputtering  

NASA Astrophysics Data System (ADS)

A surface modification method was carried out by reactive DC magnetron sputtering to fabricate TiO2 electrodes coated with insulating MgO for dye-sensitized solar cells. The MgO-coated TiO2 electrode had been characterized by x-ray photoelectron spectroscopy (XPS), energy-dispersive x-ray spectroscopy (EDX), scanning electron microscopy (SEM), UV-vis spectrophotometer, cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The study results revealed that the TiO2 modification increases dye adsorption, decreases trap states and suppresses interfacial recombination. The effects of sputtering MgO for different times on the performance of DSSCs were investigated. It indicated that sputtering MgO for 3 min on TiO2 increases all cell parameters, resulting in increasing efficiency from 6.45% to 7.57%.

Wu, Sujuan; Han, Hongwei; Tai, Qidong; Zhang, Jing; Xu, Sheng; Zhou, Conghua; Yang, Ying; Hu, Hao; Lei Chen, Bo; Sebo, Bobby; Zhao, Xing-Zhong

2008-05-01

140

Enhancement in dye-sensitized solar cells based on MgO-coated TiO(2) electrodes by reactive DC magnetron sputtering.  

PubMed

A surface modification method was carried out by reactive DC magnetron sputtering to fabricate TiO(2) electrodes coated with insulating MgO for dye-sensitized solar cells. The MgO-coated TiO(2) electrode had been characterized by x-ray photoelectron spectroscopy (XPS), energy-dispersive x-ray spectroscopy (EDX), scanning electron microscopy (SEM), UV-vis spectrophotometer, cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The study results revealed that the TiO(2) modification increases dye adsorption, decreases trap states and suppresses interfacial recombination. The effects of sputtering MgO for different times on the performance of DSSCs were investigated. It indicated that sputtering MgO for 3 min on TiO(2) increases all cell parameters, resulting in increasing efficiency from 6.45% to 7.57%. PMID:21730583

Wu, Sujuan; Han, Hongwei; Tai, Qidong; Zhang, Jing; Xu, Sheng; Zhou, Conghua; Yang, Ying; Hu, Hao; Chen, Bolei; Sebo, Bobby; Zhao, Xing-Zhong

2008-05-28

141

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

PubMed

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

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

2014-04-21

142

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

143

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

144

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

145

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

146

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

PubMed

TiO2 nanorod (NR) and nanotube (NT) arrays grown on transparent conductive substrates are attractive electrode for solar cells. In this paper, TiO2 NR arrays are hydrothermally grown on FTO substrate, and are in situ converted into NT arrays by hydrothermally etching. The TiO2 NR arrays are reported as single crystalline, but the TiO2 NR arrays are demonstrated to be polycrystalline with a bundle of 2-5 nm single crystalline nanocolumns grown along [001] throughout the whole NR from bottom to top. TiO2 NRs can be converted to NTs by hydrothermal selective etching of the (001) core and remaining the inert sidewall of (110) face. A growth mechanism of the NR and NT arrays is proposed. Quantum dot-sensitized solar cells (QDSCs) are fabricated by coating CdSe QDs on to the TiO2 arrays. After conversion from NRs to NTs, more QDs can be filled in the NTs and the energy conversion efficiency of the QDSCs almost double. PMID:23606243

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

2013-09-23

147

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

NASA Astrophysics Data System (ADS)

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

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

2010-10-01

148

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

NASA Astrophysics Data System (ADS)

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

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

2010-07-01

149

Improving the performance of quantum dot-sensitized solar cells by using TiO2 nanosheets with exposed highly reactive facets.  

PubMed

We demonstrated CdS quantum dot-sensitized solar cells (QDSSCs) based on anatase TiO2 nanosheets with exposed {001} and {100} facets. Under the illumination of one Sun (AM 1.5 G, 100 mW cm(-2)), the photovoltaic conversion efficiencies were 2.29% for a QDSSC based on {001}-TiO2 nanosheets, 2.18% for a QDSSC based on {100}-TiO2 nanosheets, and 1.46% for a QDSSC based on commercial Degussa P25. It was found that the exposed highly reactive facets of TiO2 nanosheets had a remarkable influence on the QDSSCs due to their better adsorption abilities for QDs, leading to the high short current density and the enhanced photovoltaic performance. PMID:23680858

You, Ting; Jiang, Lei; Han, Ke-Li; Deng, Wei-Qiao

2013-06-21

150

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

NASA Astrophysics Data System (ADS)

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

Smestad, Greg P.

1993-10-01

151

Holographic modification of TiO2 nanostructure for enhanced charge transport in dye-sensitized solar cell  

NASA Astrophysics Data System (ADS)

We show that the photocurrent and energy conversion efficiency of dye-sensitized solar cells can be greatly enhanced with holographic modification to the morphology of TiO2 electrode. The nanoporous electrode coated onto conducting glass was irradiated by three interfering laser beams at 1064 nm incident from the backside of the substrate. This generated two-dimensional periodic pillars of higher density in the electrode, through which the photoexcited electrons could be extracted more effectively. The cells fabricated with modified electrodes exhibited average photocurrent and efficiency of 17.14 mA/cm2 and 9.03%, while 14.91 mA/cm2 and 7.83% were obtained from the reference cells. It was attributed to the enhanced charge transport accompanied by the reduction of internal resistance of the electrode.

Lee, Jinsoo; Yoon, Junghwan; Jin, Minhea; Lee, Myeongkyu

2012-08-01

152

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

NASA Astrophysics Data System (ADS)

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

Abdullah, M. H.; Rusop, M.

2013-11-01

153

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

NASA Astrophysics Data System (ADS)

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

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

2010-03-01

154

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

NASA Astrophysics Data System (ADS)

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

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

2013-11-01

155

Use of highly-ordered TiO(2) nanotube arrays in dye-sensitized solar cells.  

PubMed

We describe the use of highly ordered transparent TiO(2) nanotube arrays in dye-sensitized solar cells (DSCs). Highly ordered nanotube arrays of 46-nm pore diameter, 17-nm wall thickness, and 360-nm length were grown perpendicular to a fluorine-doped tin oxide-coated glass substrate by anodic oxidation of a titanium thin film. After crystallization by an oxygen anneal, the nanotube arrays are treated with TiCl(4) to enhance the photogenerated current and then integrated into the DSC structure using a commercially available ruthenium-based dye. Although the negative electrode is only 360-nm-thick, under AM 1.5 illumination the generated photocurrent is 7.87 mA/cm(2), with a photocurrent efficiency of 2.9%. Voltage-decay measurements indicate that the highly ordered TiO(2) nanotube arrays, in comparison to nanoparticulate systems, have superior electron lifetimes and provide excellent pathways for electron percolation. Our results indicate that remarkable photoconversion efficiencies may be obtained, possibly to the ideal limit of approximately 31% for a single photosystem scheme, with an increase of the nanotube-array length to several micrometers. PMID:16464037

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

2006-02-01

156

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

PubMed

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

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

2013-12-01

157

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

PubMed

The enhanced photoelectric performance of quantum dot sensitized solar cells via hydrogenated TiO2 is proposed. The best energy conversion efficiency is 1.5 times higher than cells without hydrogen treatment. We demonstrated that introducing oxygen vacancies by hydrogenation is an effective and feasible method for enhanced photoelectric performance. PMID:25010989

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

2014-07-24

158

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

159

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

NASA Astrophysics Data System (ADS)

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

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

2013-11-01

160

Mesoporous TiO2 anodes for efficient dye-sensitized solar cells: An efficiency of 9.86% under one sun illumination  

NASA Astrophysics Data System (ADS)

Enhancement of power conversion efficiency has been a long-term objective for dye-sensitized solar cells (DSSCs). In the current work, mesoporous TiO2 anodes are synthesized by a gel-hydrothermal method using polyvinylpyrrolidone (PVP) as a pore-forming agent in order to elevate the dye loading, incident light illumination for dye excitation as well as electron transportation along conducting channels from TiO2 nanoparticles. In comparison with dense TiO2 anode, the dye illumination is also significantly enhanced, resulting in an increased photoelectron density on conduction band of TiO2. The photovoltaic performances are optimized by adjusting PVP dosage in synthesizing mesoporous TiO2 anode. An impressive power conversion efficiency of 9.86% is recorded under one sun illumination. The power conversion efficiency is increased by ?53.8% in comparison with the dense TiO2 anode based DSSC. The high conversion efficiency in combination with simple preparation demonstrates the potential use of the approach in designing efficient DSSCs.

Hu, Bingbing; Tang, Qunwei; He, Benlin; Lin, Lin; Chen, Haiyan

2014-12-01

161

Modification of TiO2 Electrode with Organic Silane Interposed Layer for High-Performance of Dye-Sensitized Solar Cells.  

PubMed

Back electron transfer from the TiO2 electrode surface to the electrolyte is the main reason behind the low-open circuit potential (Voc) and the low-fill factor (FF) of the dye-sensitized solar cells (DSSCs). Modifications to the TiO2 electrode, fabricated using {010}-faceted TiO2 nanoparticles with six different kinds of silane, are reported to decrease the back electron transfer on the TiO2 surface. The effect of alkyl chain length of hydrocarbon silanes and fluorocarbon silanes on adsorption parameters of surface coverage and adsorption constant, interfacial resistance, and photovoltaic performances were investigated. Adsorption isotherms, impedance analysis, and photovoltaic measurements were used as the investigation techniques. The reduction of back electron transfer depended on the TiO2 surface coverage by silane, alkyl chain length, and the molecular structure of the silane. Even though Voc and FF were improved, significant reduction in short-circuit photocurrent density (Jsc) was observed after silanization because of desorption of dye during silanization. A new approach, sequential adsorption process of silane and dye, was introduced to enhance Voc and FF without lowering Jsc. Heptadecafluorodecyl trimethoxy-silane showed the highest coverage on the surface of the TiO2 and had the highest effect on the performance improvement of the DSSC, where Voc, FF, and efficiency (?) were improved by 22, 8.0, and 22%, respectively. PMID:24684283

Sewvandi, Galhenage A; Tao, Zhuoqi; Kusunose, Takafumi; Tanaka, Yasuhiro; Nakanishi, Shunsuke; Feng, Qi

2014-04-23

162

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

PubMed

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

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

2014-04-01

163

Influence of TiO2 nanotube morphology and TiCl4 treatment on the charge transfer in dye-sensitized solar cells  

NASA Astrophysics Data System (ADS)

Dye-sensitized solar cells (DSSCs) were fabricated using TiO2 nanoparticles (NPs), TiO2 nanotube arrays (NTAs), and surface-modified NTAs with a TiCl4 treatment. The photovoltaic efficiencies of the DSSCs using TiO2 NP, NTA, and TiCl4-treated NTA electrodes are 4.25, 4.74, and 7.47 %, respectively. The highest performance was observed with a TiCl4-treated TiO2 NTA photoanode, although in the case of the latter two electrodes, the amounts of N719 dye adsorbed were similar and 68 % of that of the NP electrode. Electrochemical impedance measurements show that the overall resistance, including the charge-transfer resistance, was smaller with NTA morphologies than with NP morphologies. We suggest that a different electron transfer mechanism along the one-dimensional nanostructure of the TiO2 NTAs contributes to the smaller charge-transfer resistance, resulting in a higher short circuit current ( J sc), even at lower dye adsorption. Furthermore, the TiCl4-treated NTAs showed even smaller charge-transfer resistance, resulting in the highest J sc value, because the downward shift in the conduction band edge improves the electron injection efficiency from the excited dye into the TiCl4-treated TiO2 electrodes.

Lee, Sun Hong; Chae, Sang Youn; Hwang, Yun Jeong; Koo, Kee-Kahb; Joo, Oh-Shim

2013-09-01

164

Hierarchical TiO2 flowers built from TiO2 nanotubes for efficient Pt-free based flexible dye-sensitized solar cells.  

PubMed

A novel hierarchical TiO(2) flower consisting of anatase TiO(2) nanotubes on a Ti foil substrate has been prepared via a mild hydrothermal reaction of TiO(2) nanoparticles/Ti foil. The photovoltaic performance of DSSC based on hierarchical TiO(2) flowers/Ti (7.2%) is much higher than that of TiO(2) nanoparticle/Ti (6.63%) because of its superior light scattering ability and fast electron transport. Moreover, full flexible DSSC based on the novel hierarchical TiO(2) flowers/Ti foil photoelectrode and electrodeposited poly(3,4-ethylenedioxythiophene) (PEDOT) on indium tin oxide-coated poly(ethylene terephthalate) (ITO-PET) counter electrode shows a significant power conversion efficiency of 6.26%, accompanying a short-circuit current density of 11.96 mA cm(-2), an open-circuit voltage of 761 mV and a fill factor of 0.69. PMID:22914771

Lei, Bing-Xin; Luo, Qiu-Ping; Yu, Xiao-Yun; Wu, Wu-Qiang; Su, Cheng-Yong; Kuang, Dai-Bin

2012-10-14

165

Equivalent Circuit Analysis of Dye-Sensitized Solar Cell by Using One-Diode Model: Effect of Carboxylic Acid Treatment of TiO2 Electrode  

Microsoft Academic Search

For the improvement of dye-sensitized solar cell performance, it is important to analyze the electric mechanism of cells and to employ an effective treatment. Equivalent circuit analysis using a one-diode model was carried out for a dye-sensitized solar cell consisting of a TiO2 electrode treated with carboxylic acid. Carboxylic acid treatment, especially using acetic acid, was effective in increasing the

Masaki Murayama; Tatsuo Mori

2006-01-01

166

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

167

A new cosensitization method using the Lewis acid sites of a TiO2 photoelectrode for dye-sensitized solar cells.  

PubMed

Co-sensitized dye-sensitized solar cells using black dye and a pyridine-anchor dye (NI5 or YNI-2) showing site-selective adsorption behaviour at the TiO2 surface have been prepared for the first time to reduce the competitive adsorption between the two dyes. PMID:24812658

Shibayama, Naoyuki; Ozawa, Hironobu; Abe, Masahiro; Ooyama, Yousuke; Arakawa, Hironori

2014-05-20

168

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

169

Synthesis and application of TiO2 single-crystal nanorod arrays grown by multicycle hydrothermal for dye-sensitized solar cells  

NASA Astrophysics Data System (ADS)

TiO2 is a wide band gap semiconductor with important applications in photovoltaic cells. Vertically aligned TiO2 nanorod arrays (NRs) are grown on the fluorine-doped tin oxide (FTO) substrates by a multicycle hydrothermal synthesis process. The samples are characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), and selected-area electron diffraction (SAED). It is found that dye-sensitized solar cells (DSSCs) assembled by the as-prepared TiO2 single-crystal NRs exhibit different trends under the condition of different nucleation and growth concentrations. Optimum cell performance is obtained with high nucleation concentration and low growth cycle concentration. The efficiency enhancement is mainly attributed to the improved specific surface area of the nanorod.

Zhu, Jian-Jing; Zhao, Yu-Long; Zhu, Lei; Gu, Xiu-Quan; Qiang, Ying-Huai

2014-04-01

170

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

NASA Astrophysics Data System (ADS)

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

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

2006-06-01

171

Dye-sensitized solar cells based on oriented ZnO nanowire-covered TiO 2 nanoparticle composite film electrodes  

Microsoft Academic Search

The oriented ZnO nanowire-covered TiO2 nanoparticle composite film electrodes were fabricated by screen-printed TiO2 nanoparticle layer on conducting glass and low-temperature hydrothermal growth of ZnO nanowires. The film morphology, composition and crystalline structure were confirmed by field-emission scanning electron microscopy, energy dispersive X-ray spectra and X-ray diffraction patterns respectively. Dye-sensitized solar cells based on the composite electrode gained short-circuit current

Yuqiao Wang; Yueming Sun; Kang Li

2009-01-01

172

Unique TiO 2 paste for high efficiency dye-sensitized solar cells  

Microsoft Academic Search

A novel titanium oxide paste based on Pechini sol–gel method and nanocrystalline titanium oxide powder have been successfully developed. Titanium oxide layers possess high inner surface area assuring high dye loading and well-connected nanocrystalline grains assuring good electron transport within the layer. The dye-sensitized layers have been used to assemble dye-sensitized solar cells with acetonitrile- and ionic liquid-based electrolyte. Overall

U. Opara Krašovec; M. Berginc; M. Ho?evar; M. Topi?

2009-01-01

173

Application of monodisperse TiO2 nanoparticles with the size of 8-10 nm in dye-sensitized solar cells  

NASA Astrophysics Data System (ADS)

In this paper, the commercial monodisperse TiO2 nanoparticles with the size of 8-10 nm were successfully applied to the photoelectrode for dye-sensitized solar cells (DSCs) and the influence of the thickness of the TiO2 thin films on the photovoltaic performance of the DSCs was investigated. The result revealed that the DSCs with the TiO2 thin film thickness of 3.6, 8.0, 11.6 and 20.0 ?m gave the photoelectric conversion efficiency of 3.67%, 5.92%, 6.71% and 7.03%, respectively, under the illumination of simulated AM 1.5 sunlight (100 mW cm-2).

Dai, Xiaoyan; Shi, Chengwu; Zhang, Yanru; Tao, Li; Hu, Linhua

2014-05-01

174

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

175

Artificial photosynthesis based on dye-sensitized nanocrystalline TiO 2 solar cells  

Microsoft Academic Search

A new series of amphiphilic heteroleptic ruthenium(II) sensitizers [Ru(H2dcbpy)(dhbpy)(NCS)2] (C1), [Ru(H2dcbpy)(bccbpy)(NCS)2] (C2), [Ru(H2dcbpy)(mpubpy)(NCS)2] (C3), [Ru(H2dcbpy)(bhcbpy)(NCS)2] (C4) have been synthesized and fully characterized by UV–Vis, emission, NMR and cyclic voltammetric studies (where dhbpy=4,4?-dihexyl-2,2?-bipyridine, bccbpy=4,4?-bis(cholesteroxycarbonyl)-2,2?-bipyridine, mpubpy=4-methyl-4?-perfluoro-1H,1H,2H,2H,3H,3H-undecyl-2,2?-bipyridine, bhcbpy=4,4?-Bis(hexylcarboxamido)-2,2?-bipyridine). The amphiphilic amide heteroleptic ruthenium(II) sensitizers, self-assembled on TiO2 surface from ethanol solution, reveal efficient sensitization in the visible window range yielding ?80% incident photon-to-current

J.-J. Lagref; M. Grätzel

2008-01-01

176

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

PubMed

Dye-sensitized solar cells employing mesoporous TiO(2) beads have demonstrated longer electron diffusion lengths and extended electron lifetimes over Degussa P25 titania electrodes due to the well interconnected, densely packed nanocrystalline TiO(2) particles inside the beads. Careful selection of the dye to match the dye photon absorption characteristics with the light scattering properties of the beads have improved the light harvesting and conversion efficiency of the bead electrode in the dye-sensitized solar cell. This has resulted in a solar to electric power conversion efficiency (PCE) of greater than 10% (10.6% for Ru(II)-based dye C101 and 10.7% using C106) for the first time using a single screen-printed titania layer cell construction (that is, without an additional scattering layer). PMID:20731428

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

2010-08-24

177

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

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

178

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

PubMed

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

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

2014-06-21

179

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

PubMed Central

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

2013-01-01

180

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

NASA Astrophysics Data System (ADS)

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

Nguyen, Duy-Cuong; Tanaka, Souichirou; Nishino, Hitoshi; Manabe, Kyohei; Ito, Seigo

2013-01-01

181

Illumination intensity dependence of the photovoltage in nanostructured TiO2 dye-sensitized solar cells.  

PubMed

The open-circuit voltage (V(oc)) dependence on the illumination intensity (phi0) under steady-state conditions in both bare and coated (blocked) nanostructured TiO2 dye-sensitized solar cells (DSSCs) is analyzed. This analysis is based on a recently reported model [Bisquert, J.; Zaban, A.; Salvador, P. J. Phys. Chem. B 2002, 106, 8774] which describes the rate of interfacial electron transfer from the conduction band of TiO2 to acceptor electrolyte levels (recombination). The model involves two possible mechanisms: (1) direct, isoenergetic electron injection from the conduction band and (2) a two-step process involving inelastic electron trapping by band-gap surface states and subsequent isoenergetic transfer of trapped electrons to electrolyte levels. By considering the variation of V(oc) over a wide range of illumination intensities (10(10) < phi0 < 10(16) cm(-2) s(-1)), three major regions with different values of dV(oc)/d phi0 can be distinguished and interpreted. At the lower illumination intensities, recombination mainly involves localized band-gap, deep traps at about 0.6 eV below the conduction band edge; at intermediate photon fluxes, recombination is apparently controlled by a tail of shallow traps, while, for high enough phi0 values, conduction band states control the recombination process. The high phi0 region is characterized by a slope of dV(oc)/d log phi0 congruent with 60 mV, which indicates a recombination of first order in the free electron concentration. The study, which was extended to different solar cells, shows that the energy of the deep traps seems to be an intrinsic property of the nanostructured TiO2 material, while their concentration and also the density ([symbol: see text]t approximately 10(18)-10(19) cm(-3)) and distribution of shallow traps, which strongly affects the shape of the V(oc) vs phi0 curves, change from sample to sample and are quite sensitive to the electrode preparation. The influence of the back-reaction of electrons from the fluorine-doped tin oxide (FTO) conducting glass substrate with electrolyte tri-iodide ions on the V(oc) vs phi0 dependence characteristic of the DSSC is analyzed. It is concluded that this back-reaction route can be neglected, even at low light intensities, when its rate (exchange current density, j0), which can vary over 4 orders of magnitude depending on the type of FTO used, is low enough (j0 < or = 10(-8)A cm(-2)). The comparison of V(oc) vs phi0 measurements corresponding to different DSSCs with and without blocking of the FTO-electrolyte contact supports this conclusion. PMID:16853020

Salvador, P; Hidalgo, M Gonzalez; Zaban, Arie; Bisquert, Juan

2005-08-25

182

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

PubMed

The charge recombination reaction from the semiconductor (TiO(2)) conduction band to electron accepting electrolytes (I(2), I(2)(-), I(3)(-)) in dye-sensitised solar cells is investigated theoretically. The non-adiabatic theory of electron transfer has been adapted to compute the charge transfer rate measured in different experimental settings (namely with and without external illumination). In both cases we are able to provide an atomic level description of the charge recombination to the electrolyte (CRE), which is in good agreement with the experimental data available. The model employs a detailed density-functional theory (DFT) description of the semiconductor-electrolyte interface and the internal reorganization energy. A continuum dielectric model is used to evaluate the external component of the reorganization energy due to the solvent degrees of freedom. The intrinsic limitations of DFT are kept to a minimum by taking two key energetic parameters (the conduction band edge and the reaction energy) from the experiments. The proposed methodology correctly reproduces (i) the ratio between CRE rate to iodine and triiodide in dark, (ii) the absolute CRE rate to triiodide in dark, and (iii) the absolute CRE rate to I(2)(-) under illumination. PMID:23249045

Maggio, E; Martsinovich, N; Troisi, A

2012-12-14

183

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

NASA Astrophysics Data System (ADS)

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

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

184

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

PubMed Central

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

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

2014-01-01

185

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

186

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

NASA Astrophysics Data System (ADS)

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.

Lin, Jia; Chen, Jingfei; Chen, Xianfeng

2011-07-01

187

Significant influence of TiO 2 photoelectrode morphology on the energy conversion efficiency of N719 dye-sensitized solar cell  

Microsoft Academic Search

Since Grätzel’s group reported an overall efficiency of 10% for dye-sensitized solar cell using cis-di(thiocyanato)bis(2,2?-bipyridyl-4,4?-dicarboxylate)ruthenium(II), many other institutions have tried to reproduce it. However, no other institutions have, so far, reported such a high efficiency. In order to develop high efficiency dye-sensitized solar cells, the tuning of TiO2 photoelectrode morphology towards optimization of solar energy conversion efficiency has been investigated.

Zhong-Sheng Wang; Hiroshi Kawauchi; Takeo Kashima; Hironori Arakawa

2004-01-01

188

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

PubMed

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

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

2013-11-27

189

Improved performance of dye-sensitized solar cells with TiO 2\\/alumina core–shell formation using atomic layer deposition  

Microsoft Academic Search

Alumina (Al2O3) shell formation on TiO2 core nanoparticles by atomic layer deposition (ALD) is studied to suppress the recombination of charge carriers generated in a dye-sensitized solar cell (DSSC). It is relatively easy to control the shell thickness using the ALD method by controlling the number of cycles. An optimum thickness can be identified, which allows tunneling of the forward

V. Ganapathy; B. Karunagaran; Shi-Woo Rhee

2010-01-01

190

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

Microsoft Academic Search

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

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

2005-01-01

191

High-efficiency inverted organic solar cells with polyethylene oxide-modified Zn-doped TiO2 as an interfacial electron transport layer.  

PubMed

High efficiency inverted organic solar cells are fabricated using the PTB7:PC71BM polymer by incorporating Zn-doped TiO2 (ZTO) and 0.05 wt% PEO:ZTO as interfacial electron transport layers. The 0.05 wt% PEO-modified ZTO device shows a significantly increased power conversion efficiency (PCE) of 8.10%, compared to that of the ZTO (7.67%) device. PMID:24976080

Thambidurai, M; Kim, Jun Young; Ko, Youngjun; Song, Hyung-Jun; Shin, Hyeonwoo; Song, Jiyun; Lee, Yeonkyung; Muthukumarasamy, N; Velauthapillai, Dhayalan; Lee, Changhee

2014-07-10

192

Effects of TiO2 Interfacial Atomic Layers on Device Performances and Exciton Dynamics in ZnO Nanorod Polymer Solar Cells.  

PubMed

The performances of organic electronic and/or photonic devices rely heavily on the nature of the inorganic/organic interface. Control over such hybrid interface properties has been an important issue for optimizing the performances of polymer solar cells bearing metal-oxide conducting channels. In this work, we studied the effects of an interfacial atomic layer in an inverted polymer solar cell based on a ZnO nanorod array on the device performance as well as the dynamics of the photoexcited carriers. We adopted highly conformal TiO2 interfacial layer using plasma enhanced atomic layer deposition (PEALD) to improve the compatibility between the solution-prepared active layer and the ZnO nanorod array. The TiO2 interfacial layer facilitated exciton separation and subsequent charge transfer into the nanorod channel, and it suppressed recombination of photogenerated carriers at the interface. The presence of even 1 PEALD cycle of TiO2 coating substantially improved the short-circuit current density (Jsc), open circuit voltage (Voc), and fill factor (FF), leading to more than 2-fold enhancement in the power conversion efficiency (PCE). The dynamics of the photoexcited carriers in our devices were studied using transient absorption (TA) spectroscopy. The TA results clearly revealed that the TiO2 coating played a key role as an efficient quencher of photogenerated excitons, thereby reducing the exciton lifetime. The electrochemical impedance spectra (EIS) provided further evidence that the TiO2 atomic interfacial layer promoted the charge transfer at the interface by suppressing recombination loss. PMID:24987829

Jin, Mi-Jin; Jo, Junhyeon; Kim, Ji-Hee; An, Ki-Seok; Jeong, Mun Seok; Kim, Jeongyong; Yoo, Jung-Woo

2014-07-23

193

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

PubMed Central

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

2013-01-01

194

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

PubMed

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

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

2013-01-01

195

The importance of the TiO2/quantum dots interface in the recombination processes of quantum dot sensitized solar cells.  

PubMed

Quantum dot sensitized solar cells (QDSSCs) present a promising technology for next generation photovoltaic cells, having exhibited a considerable leap in performance over the last few years. However, recombination processes occurring in parallel at the TiO(2)-QDs-electrolyte triple junction constitute one of the major limitations for further improvement of QDSSCs. Reaching higher conversion efficiencies necessitates gaining a better understanding of the mechanisms of charge recombination in these kinds of cells; this will essentially lead to the development of new solutions for inhibiting the described losses. In this study we have systematically examined the contribution of each interface formed at the triple junction to the recombination of the solar cell. We show that the recombination of electrons at the TiO(2)/QDs interface is as important as the recombination from TiO(2) and QDs to the electrolyte. By applying conformal MgO coating both above and below the QD surface, recombination rates were significantly reduced, and an improvement of more than 20% in cell efficiency was recorded. PMID:23400262

Tachan, Zion; Hod, Idan; Shalom, Menny; Grinis, Larissa; Zaban, Arie

2013-03-21

196

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

197

Low-temperature sintering for plastic dye-sensitized solar cells using conventional TiO2 paste containing organic binders  

NASA Astrophysics Data System (ADS)

Dye-sensitized solar cells (DSSCs) require sintering of TiO2 photoelectrodes at 450 °C to 550 °C. However, high-temperature sintering is unfavorable because it limits the use of materials that cannot withstand high temperatures. In previous papers, we proposed a surface treatment of TiO2 photoelectrodes to reduce the sintering temperature from 500 °C to 250 °C using a dielectric barrier discharge and ultraviolet light from a low-pressure mercury lamp. In this study, we improved the surface treatment of TiO2 photoelectrodes to further reduce the sintering temperature from 250 °C to 150 °C using a conventional TiO2 paste that contains organic binders. The sintering temperature of 150 °C is critical because it is the maximum tolerable temperature of plastic substrates. The improved surface treatment is applied to both glass and plastic substrate DSSCs. The energy conversion efficiency of glass and plastic substrate DSSCs sintered at 150 °C using our improved surface treatment are approximately 110% and 80%, respectively, of that of glass substrate DSSCs fabricated using the conventional method sintered at 500 °C.

Zen, Shungo; Ishibashi, Yuta; Ono, Ryo

2014-05-01

198

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

NASA Astrophysics Data System (ADS)

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.

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

2010-12-01

199

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

NASA Astrophysics Data System (ADS)

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

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

2009-12-01

200

Effect of Acetic Acid in TiCl4 Post-Treatment on Nanoporous TiO2 Electrode in Dye-Sensitized Solar Cell  

NASA Astrophysics Data System (ADS)

Titanium tetrachloride (TiCl4) is adopted as a post-treatment on the nanoporous titanium oxide (TiO2) layers to enhance the performance of dye-sensitized solar cells (DSCs). A TiCl4 post-treatment is capable of improving electron transport and dye-loading on the surface of TiO2 layers. In this study, the TiCl4 solution mixed with acetic acid was employed to enhance the condition of the TiCl4 post-treatment. Since acetic acid in the TiCl4 solution prevents the formation of impurities and facilitates the crystallization, it improves dye adsorption and electron transport properties. To analyze the performance of the cell, we measured X-ray diffraction (XRD), scanning electron microscopy (SEM), Brunauer--Emmett--Teller (BET) surface measurements, UV--vis spectroscopy and electrochemical impedance spectroscopy (EIS) and photocurrent--voltage (I--V) measurements.

Kim, Soo-Kyoung; Son, Min-Kyu; Kim, Jin-Kyoung; Kim, Byung-Man; Hong, Na-Yeong; Prabakar, Kandasamy; Kim, Hee-Je

2012-09-01

201

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

202

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

NASA Astrophysics Data System (ADS)

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

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

2011-11-01

203

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

PubMed

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

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

2012-11-01

204

Atomic layer deposition of TiO2 on mesoporous nanoITO: conductive core-shell photoanodes for dye-sensitized solar cells.  

PubMed

Core-shell structures consisting of thin shells of conformal TiO2 deposited on high surface area, conductive Sn-doped In2O3 nanoparticle. Mesoscopic films were synthesized by atomic layer deposition and studied for application in dye-sensitized solar cells. Results obtained with the N719 dye show that short-circuit current densities, open-circuit voltages, and back electron transfer lifetimes all increased with increasing TiO2 shell thickness up to 1.8-2.4 nm and then decline as the thickness was increased further. At higher shell thicknesses, back electron transfer to -Ru(III) is increasingly competitive with transport to the nanoITO core resulting in decreased device efficiencies. PMID:24846703

Alibabaei, Leila; Farnum, Byron H; Kalanyan, Berç; Brennaman, M Kyle; Losego, Mark D; Parsons, Gregory N; Meyer, Thomas J

2014-06-11

205

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

206

Characteristics of TiO 2/solid electrolyte junction solar cells with I-/I3- redox couple  

NASA Astrophysics Data System (ADS)

Solid electrolytes comprising 55 wt.%chitosan-45 wt.%NH 4I, 33 wt.%chitosan-27 wt.%NH 4I-40 wt.%EC (ethylene carbonate) and 11 wt.%chitosan-9 wt.%NH 4I-80 wt.%BMII (1-butyl-3-methylimidazolium iodide) have been prepared by the solution cast technique. The conductivity for the 55 wt.%chitosan-45 wt.%NH 4I electrolyte is 3.73 × 10 -7 S cm -1 at room temperature. Complexation between polymer and salt has been proven by Fourier transform infrared (FTIR) spectroscopy where the carbonyl and amine bands in the spectrum of chitosan acetate shifted from 1645 and 1557 cm -1-1618 and 1508 cm -1 in the polymer-salt spectrum. The addition of 40 wt.%EC to the 55 wt.%chitosan-45 wt.%NH 4I electrolyte increased its conductivity to 7.34 × 10 -6 S cm -1. The conductivity of the chitosan-NH 4I electrolyte increased to 8.47 × 10 -4 S cm -1 at room temperature on addition of 80 wt.%BMII. The plasticizer containing electrolyte is still a free standing film. The ionic liquid incorporated electrolyte is still solid, but with reduced mechanical stability due to the low polymer content. This shows that at such low content, chitosan is still able to host ionic conduction. A photovoltaic cell with configuration ITO/titanium dioxide (TiO 2)-solid electrolyte with I-/I3- redox couple/ITO has been constructed using each electrolyte system. The short-circuit current density, J sc and open-circuit voltage, OCV obtained from the cell employing the polymer-salt electrolyte under white light illumination of intensity 56.4 mW cm -2 are 4.99 ?A cm -2 and 0.15 V, respectively. The OCV for the cell with plasticizer containing electrolyte is 0.22 V and its J sc is 7.28 ?A cm -2. The solar cell with ionic liquid incorporated in the solid electrolyte exhibited an OCV of 0.26 V and J sc of 19.23 ?A cm -2, respectively.

Buraidah, M. H.; Teo, L. P.; Majid, S. R.; Arof, A. K.

2010-04-01

207

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

208

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

2013-11-21

209

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

210

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

211

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

SciTech Connect

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

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

2012-06-01

212

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

213

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

PubMed

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

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

2012-01-28

214

Formulations and processing of nanocrystalline TiO2 films for the different requirements of plastic, metal and glass dye solar cell applications  

NASA Astrophysics Data System (ADS)

We carried out a systematic study on the effect of nanocrystalline TiO2 paste formulations and temperature treatment on the performance of dye solar cells (DSCs) over a large temperature range, to provide useful information for the fabrication of both plastic and metal flexible devices. We compared conventional screen-printable and binder-free TiO2 pastes with a new formulation which includes hydroxylethyl cellulose (HEC), enabling the study of the effect of organic materials in the TiO2 layer in the whole 25-600?° C temperature range. Differently from the binder-free formulations where the device efficiency rose monotonically with temperature, the use of cellulose binders led to remarkably different trends depending on their pyrolysis and decomposition thresholds and solubility, especially at those temperatures compatible with plastic foils. Above 325?° C, where metal foil can be used as substrates, the efficiencies become similar to those of the binder-free paste due to effective binder decomposition and inter-nanoparticle bonding. Finally, we demonstrated, for the first time, that the simultaneous application of both temperature (110-150?° C) and pressure (100 MPa) can lead to a large improvement (33%) compared to the same mechanical compression method carried out at room temperature only.

Zardetto, Valerio; De Angelis, Gabriele; Vesce, Luigi; Caratto, Valentina; Mazzuca, Claudia; Gasiorowski, Jacek; Reale, Andrea; Di Carlo, Aldo; Brown, Thomas M.

2013-06-01

215

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

PubMed

Porous TiO(2) nanotube arrays with three-dimensional (3D) interconnectivity were prepared using a sol-gel process assisted by poly(vinyl chloride-graft-4-vinyl pyridine), PVC-g-P4VP graft copolymer and a ZnO nanorod template. A 7 µm long ZnO nanorod array was grown from the fluorine-doped tin oxide (FTO) glass via a liquid phase deposition method. The TiO(2) sol-gel solution templated by the PVC-g-P4VP graft copolymer produced a random 3D interconnection between the adjacent ZnO nanorods during spin coating. Upon etching of ZnO, TiO(2) nanotubes consisting of 10-15 nm nanoparticles were generated, as confirmed by wide-angle x-ray scattering (WAXS), energy-filtering transmission electron microscopy (EF-TEM) and field-emission scanning electron microscopy (FE-SEM). The ordered and interconnected nanotube architecture showed an enhanced light scattering effect and increased penetration of polymer electrolytes in dye-sensitized solar cells (DSSC). The energy conversion efficiency reached 1.82% for liquid electrolyte, and 1.46% for low molecular weight (M(w)) and 0.74% for high M(w) polymer electrolytes. PMID:21836328

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

2011-09-01

216

Hydrothermal fabrication of quasi-one-dimensional single-crystalline anatase TiO2 nanostructures on FTO glass and their applications in dye-sensitized solar cells.  

PubMed

One-dimensional and quasi-one-dimensional semiconductor nanostructures are desirable for dye-sensitized solar cells (DSSCs), since they can provide direct pathways for the rapid collection of photogenerated electrons, which could improve the photovoltaic performance of the device. Quasi-1D single-crystalline anatase TiO(2) nanostructures have been successfully prepared on transparent, conductive fluorine-doped tin oxide (FTO) glass with a growth direction of [101] through a facile hydrothermal approach. The influences of the initial titanium n-butoxide (TBT) concentration, hydrothermal reaction temperature, and time on the length of quasi-1D anatase TiO(2) nanostructures and on the photovoltaic performance of DSSCs have been investigated in detail. A power conversion efficiency of 5.81% has been obtained based on the prepared TiO(2) nanostructure photoelectrode 6.7 ?m thick and commercial N719 dye, with a short-circuit current density of 13.3 mA cm(-2) , an open-circuit voltage of 810 mV, and a fill factor of 0.54. PMID:21243703

Liao, Jin-Yun; Lei, Bing-Xin; Wang, Yu-Fen; Liu, Jun-Min; Su, Cheng-Yong; Kuang, Dai-Bin

2011-01-24

217

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

PubMed

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

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

2012-01-21

218

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

NASA Astrophysics Data System (ADS)

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, as well as their initial application in dye-sensitized solar cells and hydrogen production by water photoelectrolysis. The highly-ordered TiO2 nanotube arrays are fabricated by potentiostatic anodization of Ti foil in fluoride ion containing baths in combination with non-aqueous organic polar electrolytes including N-methylformamide, dimethyl sulfoxide, formamide, or ethylene glycol. Depending upon the anodization voltage, the inner pore diameters of the resulting nanotube arrays range from 20 to 150 nm. As confirmed by glancing angle x-ray diffraction and HRTEM studies, the as-prepared nanotubes are amorphous but crystallize with annealing at elevated temperatures.

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

2007-02-01

219

Effect of sol-gel ZnO spin-coating on the performance of TiO2-based dye-sensitized solar cell  

NASA Astrophysics Data System (ADS)

Dye-sensitized solar cells (DSSCs) with ZnO spin-coated TiO2 electrodes are compared to a DSSC with a bare TiO2 electrode. It is demonstrated that the ZnO of controlled amount, by varying the number of sol drops and the precursor concentration during coating, can indeed enhance the performance of the DSSC. The maximum DSSC efficiency is obtained with a single sol drop at a precursor concentration between 0.1 M and 0.2 M, with an enhancement of over 100%. In the light of measured optical absorption spectra of the different films and desorbed dye solutions, the results are interpreted in terms of two competing factors: The formation of an energy barrier which increases the photocurrent by reducing the rate of interfacial electron back-recombination and the reduction of the dye-adsorption efficiency of the TiO2 film with increasing ZnO amount in the coating ZnO layer.

Al-juaid, Fahd; Merazga, Amar; Al-Baradi, Ateyyah; Abdel-wahab, Fouad

2013-09-01

220

Improved properties of dye-sensitized solar cells by multifunctional scattering layer of yolk-shell-like TiO2 microspheres  

NASA Astrophysics Data System (ADS)

Novel yolk-shell-like TiO2 hierarchical microspheres (YSTHSs) were synthesized by a facile one-pot hydrothermal method. These YSTHSs exhibited excellent light scattering ability and high specific surface area for more dye adsorption. A YSTHSs multifunctional scattering layer was fabricated on top of a conventional TiO2 nanocrystalline layer (T) to form a heterostructure bilayer photoanode (T-YSTHS). The influences of the YSTHSs on the properties of the photoanode and dye-sensitized solar cell (DSSC) were investigated. Studies indicated that by introducing the YSTHSs, the light scattering, dye loading, electron mobility and lifetime of this bilayer photoanode were remarkably increased, resulting in the great enhancement in the short-circuit current density (Jsc) and thus the photoelectric conversion efficiency (PCE) of the DSSCs. This T-YSTHS based DSSC exhibited the maximum Jsc of 16.35 mA cm-2 and PCE of 6.01%, remarkably higher than those of the conventional TiO2 nanocrystalline (2T)-based DSSC by 27.1% and 20.4%, respectively. The remarkable enhancement in Jsc and PCE for the T-YSTHS-based DSSC compared to the 2T-based DSSCs are mainly attributed to the significant enhancement in light scattering and the increase in the specific surface area for dye adsorption due to the unique yolk-shell hierarchical microsphere structure of the YSTHSs.

Guo, Kaimo; Li, Meiya; Fang, Xiaoli; Bai, Lihua; Luoshan, Mengdai; Zhang, Fuping; Zhao, Xingzhong

2014-10-01

221

A double layered TiO2 photoanode consisting of hierarchical flowers and nanoparticles for high-efficiency dye-sensitized solar cells  

NASA Astrophysics Data System (ADS)

We report the innovative development of a double layered photoanode made of hierarchical TiO2 flowers (HTFs) as the overlayer and TiO2 nanoparticles (TNPs) as the underlayer, for dye-sensitized solar cells (DSSCs). They were prepared via a mild and simple one-step hydrothermal reaction of TiO2 nanoparticles/FTO glass substrate in an alkaline solution. The underlayer made of TNPs with a small size (20 nm in diameter) serves as a transparent photoanode for efficient dye adsorption. The overlayer consisting of HTFs (3-5 ?m in diameter) embedded by TiO2 nanosheets plays multiple roles in enhancing light-scattering and fast electron transport. DSSCs based on this novel double layered photoanode (5 ?m TNPs + 5 ?m HTFs) exhibit greater than 7.4% power conversion efficiency (PCE), which is higher than that of single layer TNP based photoanodes (6.59%) with similar thickness (~10 ?m), and this is mainly attributed to the superior light scattering ability and fast electron transport of the former. Meanwhile, the thickness of the TNP underlayer has been optimized to further improve the PCE and an excellent PCE of over 9% has been achieved based on a 15 ?m TNP + a 5 ?m HTF double layered photoanode, accompanied by a short-circuit photocurrent density of 17.85 mA cm-2, an open-circuit voltage of 763 mV and a fill factor of 0.67.We report the innovative development of a double layered photoanode made of hierarchical TiO2 flowers (HTFs) as the overlayer and TiO2 nanoparticles (TNPs) as the underlayer, for dye-sensitized solar cells (DSSCs). They were prepared via a mild and simple one-step hydrothermal reaction of TiO2 nanoparticles/FTO glass substrate in an alkaline solution. The underlayer made of TNPs with a small size (20 nm in diameter) serves as a transparent photoanode for efficient dye adsorption. The overlayer consisting of HTFs (3-5 ?m in diameter) embedded by TiO2 nanosheets plays multiple roles in enhancing light-scattering and fast electron transport. DSSCs based on this novel double layered photoanode (5 ?m TNPs + 5 ?m HTFs) exhibit greater than 7.4% power conversion efficiency (PCE), which is higher than that of single layer TNP based photoanodes (6.59%) with similar thickness (~10 ?m), and this is mainly attributed to the superior light scattering ability and fast electron transport of the former. Meanwhile, the thickness of the TNP underlayer has been optimized to further improve the PCE and an excellent PCE of over 9% has been achieved based on a 15 ?m TNP + a 5 ?m HTF double layered photoanode, accompanied by a short-circuit photocurrent density of 17.85 mA cm-2, an open-circuit voltage of 763 mV and a fill factor of 0.67. Electronic supplementary information (ESI) available. See DOI: 10.1039/c3nr00508a

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

2013-05-01

222

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

PubMed

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

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

2013-07-22

223

Layer-by-Layer Self-Assembly of TiO2 Hierarchical Nanosheets with Exposed {001} Facets As an Effective Bifunctional Layer for Dye-Sensitized Solar Cells.  

PubMed

Layer-by-layer self-assembled TiO2 hierarchical nanosheets with exposed {001} facets have been successfully fabricated via a simple one-step solvothermal reaction. The anatase TiO2 layer-by-layer hierarchical nanosheets (TiO2 LHNs) exhibit favorable light scattering effect and large surface area, owing to their layer-by-layer hierarchical structure. When applied to the dye-sensitized solar cells (DSSCs), the layer-by-layer hierarchical structure with exposed {001} facet could effectively enhance light harvesting and dye adsorption, followed by increasing the photocurrent of DSSCs. As a result, the photoelectric conversion efficiency (?) of 7.70% has been achieved for the DSSCs using TiO2 LHNs as the bifunctional layer, indicating 21% improvement compared to the pure Degussa P25 (6.37%) as photoanode. Such enhancement can be mainly ascribed to the better light scattering capability of TiO2 LHNs, higher dye adsorption on TiO2 LHN {001} facets, and longer lifetime of the injected electrons in TiO2 LHNs compared to P25, which are examined by UV-vis spectrophotometry and electrochemical impedance spectroscopy under the same conditions. These remarkable properties of TiO2 LHNs make it a promising candidate as a bifunctional scattering material for DSSCs. PMID:24881671

Sun, Weiwei; Peng, Tao; Liu, Yumin; Yu, Wenjing; Zhang, Kun; Mehnane, Hadja Fatima; Bu, Chenghao; Guo, Shishang; Zhao, Xing-Zhong

2014-06-25

224

Modified Two-Step Deposition Method for High-Efficiency TiO2/CH3NH3PbI3 Heterojunction Solar Cells.  

PubMed

Hybrid organic-inorganic perovskites (e.g., CH3NH3PbI3) are promising light absorbers for the third-generation photovoltaics. Herein we demonstrate a modified two-step deposition method to fabricate a uniform CH3NH3PbI3 capping layer with high-coverage and thickness of 300 nm on top of the mesoporous TiO2. The CH3NH3PbI3 layer shows high light-harvesting efficiency and long carrier lifetime over 50 ns. On the basis of the as-prepared film, TiO2/CH3NH3PbI3 heterojunction solar cells achieve a power conversion efficiency of 10.47% with a high open-circuit voltage of 948 mV, the highest recorded to date for hole-transport-material-free (HTM-free) perovskite-based heterojunction cells. The efficiency exceeding 10% shows promising prospects for the HTM-free solar cells based on organic lead halides. PMID:24830329

Shi, Jiangjian; Luo, Yanhong; Wei, Huiyun; Luo, Jianheng; Dong, Juan; Lv, Songtao; Xiao, Junyan; Xu, Yuzhuan; Zhu, Lifeng; Xu, Xin; Wu, Huijue; Li, Dongmei; Meng, Qingbo

2014-06-25

225

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

226

Solar hydrogen production by water splitting using TiO2 based photoelectrodes  

NASA Astrophysics Data System (ADS)

Photoelectrochemical water splitting into H2 and O2 was investigated using TiO2 based photoelectrodes. First, influence of photoelectorde structure on water splitting was studied through photocurrent observation. Solar energy conversion efficiency to H2 (STH) of mesoporous TiO2 photoelectode, composed of anatase TiO2 particles of 20nm in diameter, with 10? thickness on FTO glass was 0.32% under 0.4V vs RHE, producing 0.39mA/cm2. The quantum efficiency of water splitting at 360nm was 27%. Then, visible light absorbing mesoporous N-doped and S-doped anatase TiO2 photoelectrodes were studied. Visible light absorbing properties of these photoelectrodes were dramatically decreased with increasing calcination temperature to 550°C. However, photocurrent such as 1?A/cm2 was observed under 0.94V vs RHE and visible light irradiation using 300W-Xe lamp with 410nm cut off filter. Overall photocurrent of N-doped and S-doped TiO2 photoelectrode was about 1/5 to 1/10 of that of non-doped TiO2 photoelectrodes. Finally, solar hydrogen production by a tandem cell, composed of a mesoporous TiO2 based photoelectrode, a Pt wire electrode and a Black dye-sensitized solar cell, was studied. STH of a non-doped TiO2 photoelectrode system was 0.53% but STH of a S-doped TiO2 photoelectrode system was 0.15%, which was 1/3 lower than that of a non-doped TiO2 photoelectrodes.

Arakawa, Hironori; Shiraishi, Chikara; Takeuchi, Akihito; Yamaguchi, Takeshi

2006-09-01

227

TiO 2 @MgO core-shell film: Fabrication and application to dye-sensitized solar cells  

Microsoft Academic Search

In this study, TiO2@MgO core-shell film was obtained by using a simple chemical bath deposition method to coat a thin MgO film around TiO2 nanoparticles. The core-shell configuration was characterized by X-ray diffractometer (XRD), scanning electron microscopy\\u000a (SEM), energy dispersive X-ray spectroscopy (EDX), and high-resolution transmission electron microscopy (HRTEM). Lattice fringes\\u000a were observed for the TiO2 particles, and the MgO

Bihui Li; Gang Lü; Lijuan Luo; Yiwen Tang

2010-01-01

228

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

229

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

230

Synthesis and characterization of TiO2/SiO2 nano composites for solar cell applications  

NASA Astrophysics Data System (ADS)

The use of titania-silica in photocatalytic process has been proposed as an alternative to the conventional TiO2 catalysts. Mesoporous materials have been of great interest as catalysts because of their unique textural and structural properties. Mesoporous TiO2, SiO2 nanoparticles and TiO2/SiO2 nanocomposites were successfully synthesized by sol-gel method using titanium (IV) isopropoxide, tetra-ethylorthosilicate as starting materials. The synthesized samples are characterized by X-ray diffraction, UV-Vis spectroscopy, Fourier transform infrared spectroscopy, Brunauett-Emmett-Teller and field-dependent photoconductivity. The UV-Vis spectrum of as-synthesized samples shows similar absorption in the visible range. The crystallite size of the as-synthesized samples was calculated by Scherrer's formula. The BET surface area for TiO2/SiO2 nanocomposite is found to be 303 m2/g and pore size distribution has average pore diameter about 10 nm. It also confirms the absence of macropores and the presence of micro and mesopores. The field-dependent photoconductivity of TiO2/SiO2 nanocomposite shows nearly 300 folds more than that of TiO2 nanoparticle for a field of 800 V/cm.

Arun Kumar, D.; Merline Shyla, J.; Xavier, Francis P.

2012-12-01

231

Reconstruction of the (001) surface of TiO2 nanosheets induced by the fluorine-surfactant removal process under UV-irradiation for dye-sensitized solar cells.  

PubMed

The champion dye-sensitized solar cells (DSSCs) based on TiO(2) nanoparticles nearly reach the limit of photo-current density using the black dye or zinc porphyrin dye as sensitizer. However, the way to make ordinary DSSCs more efficient as well as to understand the mechanism is still essential. Here we present an elegant UV irradiation treatment of TiO(2) nanosheets to enhance the performance of DSSCs based on the TiO(2) nanosheets via room temperature removal of inorganic surfactants and reconstruction of the (001) surface of TiO(2) nanosheets, killing two birds with one stone. UV irradiation was utilized to remove the fluorine-surfactant on the surface of anatase TiO(2) nanosheets with a high percentage of exposed {001} facets which were synthesized with the aid of hydrofluoric acid. The nanosheets treated with UV irradiation for 40 min had the advantage of improving the photoelectric conversion efficiency of DSSCs by 17.6%, compared to that without UV treatment when they were introduced into DSSCs as photoanode materials. The improved efficiency was ascribed to more dye adsorption. A theoretical calculation proposed that UV irradiation induced microfaceted steps on the TiO(2) surface by two domain (1 × 4) reconstruction after UV irradiating the (1 × 1) (001) surface. The microfaceted steps increase the active surface area of the TiO(2) nanosheets by increasing the exposure of titanium atoms and engendering active sites. PMID:22382572

Zhang, Jiyuan; Wang, Jiajia; Zhao, Zongyan; Yu, Tao; Feng, Jianyong; Yuan, Yongjun; Tang, Zekun; Liu, Yunhong; Li, Zhaosheng; Zou, Zhigang

2012-04-14

232

Hybrid solar cells based on MEH-PPV and thin film semiconductor oxides (TiO 2, Nb 2O 5, ZnO, CeO 2 and CeO 2–TiO 2): Performance improvement during long-time irradiation  

Microsoft Academic Search

Performance improvement of hybrid solar cells (HSC) applying five different thin film semiconductor oxides has been observed during long-time irradiation in ambient atmosphere. This behavior shows a direct relation between HSC and oxygen content from the environment. Photovoltaic devices were prepared as bi-layers of thin film semiconducting oxides (TiO2, Nb2O5, ZnO, CeO2–TiO2 and CeO2) and the polymer MEH-PPV, with a

Monica Lira-Cantu; Frederik C. Krebs

2006-01-01

233

Application of ?-extended ferrocene with varied anchoring groups as photosensitizers in TiO2-based dye-sensitized solar cells (DSSCs).  

PubMed

Two new compounds, FcCH=NC(6)H(4)COOH (1) and FcCH=NCH(2)CH(2)OH (2) (Fc=C(5)H(4)FeC(5)H(5)), have been synthesized and characterized by elemental analyses, IR and (1)H NMR spectroscopy, and ESI-MS. Attempt has been made to explain their quasi-reversible redox behavior evidenced by cyclic voltammetry using density functional theory (DFT) calculations. Light-harvesting properties of both the compounds and also the starting material, FcCHO (3), have been studied using these compounds as photosensitizers in TiO(2)-based dye-sensitized solar cells having either a propylene carbonate-based electrolyte or ionic liquid electrolyte, namely, 1-propyl-3-methyl imidazolium iodide (PMII). Long-term stability of the photocurrent output of the cell using compound 1 as photosensitizer has been monitored periodically over 1400 h. PMID:21595039

Chauhan, Ratna; Trivedi, Manoj; Bahadur, Lal; Kumar, Abhinav

2011-06-01

234

Formation of single-crystalline TiO 2 nanomaterials with controlled phase composition and morphology and the application in dye-sensitized solar cell  

NASA Astrophysics Data System (ADS)

Single-crystalline TiO 2 nanomaterials with controlled phase composition and morphology were synthesized by hydrothermal transformation of H-titanate nanotubes under different pH. Rutile rectangle nanorods with two four-side tapered tips were produced at pH of 0, whereas anatase nanoparticles with mainly of rhombic shape were obtained at pH from 2 to 7 and their average particle size increased with pH. The transformation mechanisms at different pH were discussed. The single-crystalline anatase nanoparticles obtained at pH of 2 had ca. 12 nm in average particle size, and the powder possessed as large as 112 m 2/g specific surface areas; the conversion efficiency of the dye-sensitized solar cell based on the nanoparticles was increased by over 40% as compared with that of the cell based on P25.

Xu, Yuanmei; Fang, Xiaoming; Zhang, Zhengguo

2009-08-01

235

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

2012-03-01

236

Alignment of the dye's molecular levels with the TiO2 band edges in dye-sensitized solar cells: a DFT TDDFT study  

NASA Astrophysics Data System (ADS)

We present a theoretical study of the lineup of the LUMO of Ru(II)-polypyridyl (N3 and N719) molecular dyes with the conduction band edge of a TiO2 anatase nanoparticle. We use density functional theory (DFT) and the Car-Parrinello scheme for efficient optimization of the dye-nanoparticle systems, followed by hybrid B3LYP functional calculations of the electronic structure and time-dependent DFT (TDDFT) determination of the lowest vertical excitation energies. The electronic structure and TDDFT calculations are performed in water solution, using a continuum model. Various approximate procedures to compute the excited state oxidation potential of dye sensitizers are discussed. Our calculations show that the level alignment for the interacting nanoparticle-sensitizer system is very similar, within about 0.1 eV, to that for the separated TiO2 and dye. The excellent agreement of our results with available experimental data indicates that the approach of this work could be used as an efficient predictive tool to help the optimization of dye-sensitized solar cells.

DeAngelis, Filippo; Fantacci, Simona; Selloni, Annabella

2008-10-01

237

TiO2 Nanorods: A Facile Size- and Shape-Tunable Synthesis and Effective Improvement of Charge Collection Kinetics for Dye-Sensitized Solar Cells.  

PubMed

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

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

2014-06-25

238

Morphology-controlled cactus-like branched anatase TiO2 arrays with high light-harvesting efficiency for dye-sensitized solar cells  

NASA Astrophysics Data System (ADS)

The present work establishes a facile process for one-step hydrothermal growth of vertically aligned anatase cactus-like branched TiO2 (CBT) arrays on a transparent conducting oxide (TCO) substrate. Various CBT morphologies are obtained by adjusting the potassium titanium oxide oxalate (PTO) reactant concentration (from 0.05 M to 0.15 M) and this yields a morphologically-controllable branched TiO2 arrays geometry. The CBT arrays consist of a vertically oriented nanowire (NW) or nanosheet (NS) stem and a host of short nanorod (NR) branches. The hierarchical CBT arrays demonstrate their excellent candidatures as photoanodes, which are capable of exhibiting high light-harvesting efficiency in dye-sensitized solar cells (DSSCs). Consequently, DSSCs based on 7 ?m long optimized CBT arrays (0.05 M PTO), which are assembled with high density and high aspect-ratio NR branches, exhibit an impressive power conversion efficiency of 6.43% under AM 1.5G one sun illumination. The high performance can be attributed to the prominent light-harvesting efficiency, resulting from larger surface area and superior light-scattering capability.

Wu, Wu-Qiang; Rao, Hua-Shang; Feng, Hao-Lin; Guo, Xin-Dong; Su, Cheng-Yong; Kuang, Dai-Bin

239

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

PubMed

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

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

2008-10-22

240

Photocurrent enhanced dye-sensitized solar cells based on TiO2 loaded K6SiW11O39Co(II)(H2O)·xH2O photoanode materials.  

PubMed

Through loading of TiO2 on the surface of K6SiW11O39Co(II)(H2O)·xH2O (SiW11Co), a novel photoanode material has been created for dye-sensitized solar cells (DSSC). The absorbing band as well as photoelectricity response range of TiO2@SiW11Co is extended to the visible range. In addition, the absorption in the UV range is enhanced notably compared with P25 (raw TiO2). More importantly, the recombination of the TiO2 network is avoided. TiO2@SiW11Co is mixed with P25 powder (wt ?1?:?1) to assemble dye-sensitized (N719) solar cells, which exhibit a short-circuit photocurrent density as high as 18.05 mA cm(-2), which is 64% higher than blank samples under the standard AM1.5G global solar irradiation. In addition, the mechanisms for SiW11Co in DSSC are proposed. PMID:24213738

Li, Liang; Yang, YuLin; Fan, RuiQing; Wang, Xin; Zhang, Qingming; Zhang, Lingyun; Yang, Bin; Cao, Wenwu; Zhang, Wenzhi; Wang, Yazhen; Ma, Liqun

2014-01-28

241

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

PubMed

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

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

2013-01-23

242

Dye-sensitized solar cells based on TiO2 hollow spheres/TiO2 nanotube array composite films  

NASA Astrophysics Data System (ADS)

In this study, a novel double-layer electrodes with TiO2 nanotube (NT) arrays as underlayer and TiO2 hollow spheres (HSs) as overlayer film have been fabricated for application in DSSCs. Both the NTs and HSs have been synthesized and the morphology and structure were characterized by XRD, SEM and TEM. Moreover, the properties of DSSCs were investigated by UV-vis reflectance spectra, IPCE and current-voltage curves, respectively. Owing to the hollow structure, the DSSC using TiO2 HSs as light-scattering layer exhibits an enhanced light harvesting efficiency, leading to a 23% increment of cell efficiency compared to that pure TiO2 NT films.

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

2014-08-01

243

The photoelectrochemistry of transition metal-ion-doped TiO2 nanocrystalline electrodes and higher solar cell conversion efficiency based on Zn2+-doped TiO2 electrode  

Microsoft Academic Search

Metal-ion-doped TiO2 nanoparticles were prepared with hydrothermal method. The change of photocurrents at different electrode potentials and wavelengths of incident light showed two different characteristics for various transition metal-ion-doped TiO2 electrodes. In Zn2+ and Cd2+-doped TiO2 electrodes, a characteristic of n-type semiconductor was observed and the incident photon to conversion efficiency (IPCE) were larger than that of pure TiO2 electrode

Yanqin Wang; Yanzhong Hao; Humin Cheng; Jiming Ma; Bin Xu; Weihua Li; Shengmin Cai

1999-01-01

244

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

NASA Astrophysics Data System (ADS)

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

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

2012-11-01

245

Ultrafast Charge Separation Dynamics of Twisted Intramolecular Charge Transfer State (TICT) in Coumarin Dye Sensitized TiO2 Film: A New Route to Achieve Higher Efficient Dye-Sensitized Solar Cell  

NASA Astrophysics Data System (ADS)

Ultrafast transient spectroscopy of 7-diethyl amino coumarin 3-carboxylic acid (D-1421) sensitized TiO2 film reveals that TICT states facilitate higher charge separation and slow recombination and proved to be new route to design higher efficient solar cell.

Verma, Sandeep; Ghosh, Hirendra N.

2013-03-01

246

Microcrystalline based TiO2 thin film in dye-synthesized solar cell for efficient artificial photosynthesis  

Microsoft Academic Search

In today's world Global warming possesses a serious threat to mankind and society. An increase in global temperature variations is uncertain. Artificial photosynthesis is a research field that attempts to replicate the natural process of photosynthesis, converting sunlight, water, and carbon-di-oxide into carbohydrates and oxygen. One of the approaches for artificial photosynthesis is by Dyesynthesized Solar Cell. It has three

Ayan; Ankit; Aditya; Akhilesh; Nikhil

2010-01-01

247

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

Microsoft Academic Search

This article reports the development of organic dyes as an attempt to reduce material costs of Dye-Sensitized Solar Cell (DSSC). Indonesia, a country with variety and considerable number of botanical resources, is suitable to perform the research. Indonesian black rice, curcuma, papaya leaf, and the combination were chosen as organic dyes source. Dyes were extracted using organic solvent and adsorbed

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

2010-01-01

248

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

Microsoft Academic Search

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

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

2006-01-01

249

ZnO microsheet modified TiO 2 nanoparticle composite films for dye-sensitized solar cells  

Microsoft Academic Search

Randomly oriented ZnO microsheets were successfully self-assembled on TiO2 nanoparticle (TN) film to act as the scattering layer via a cathodic electrodeposition process. The light scattering properties\\u000a of ZnO microsheets were studied by UV-Vis spectrometer in the 400–800 nm wavelength range. It was found that ZnO microsheets\\u000a exhibited excellent ability to scatter the incident light for ZnO microsheet-TiO2 nanoparticle (ZT)

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

2010-01-01

250

Charge transport versus recombination in dye-sensitized solar cells employing nanocrystalline TiO2 and SnO2 films.  

PubMed

We report a comparison of charge transport and recombination dynamics in dye-sensitized solar cells (DSSCs) employing nanocrystalline TiO(2) and SnO(2) films and address the impact of these dynamics upon photovoltaic device efficiency. Transient photovoltage studies of electron transport in the metal oxide film are correlated with transient absorption studies of electron recombination with both oxidized sensitizer dyes and the redox couple. For all three processes, the dynamics are observed to be 2-3 orders of magnitude faster for the SnO(2) electrode. The origins of these faster dynamics are addressed by studies correlating the electron recombination dynamics to dye cations with chronoamperometric studies of film electron density. These studies indicate that the faster recombination dynamics for the SnO(2) electrodes result both from a 100-fold higher electron diffusion constant at matched electron densities, consistent with a lower trap density for this metal oxide relative to TiO(2), and from a 300 mV positive shift of the SnO(2) conduction band/trap states density of states relative to TiO(2). The faster recombination to the redox couple results in an increased dark current for DSSCs employing SnO(2) films, limiting the device open-circuit voltage. The faster recombination dynamics to the dye cation result in a significant reduction in the efficiency of regeneration of the dye ground state by the redox couple, as confirmed by transient absorption studies of this reaction, and in a loss of device short-circuit current and fill factor. The importance of this loss pathway was confirmed by nonideal diode equation analyses of device current-voltage data. The addition of MgO blocking layers is shown to be effective at reducing recombination losses to the redox electrolyte but is found to be unable to retard recombination dynamics to the dye cation sufficiently to allow efficient dye regeneration without resulting in concomitant losses of electron injection efficiency. We conclude that such a large acceleration of electron dynamics within the metal oxide films of DSSCs may in general be detrimental to device efficiency due to the limited rate of dye regeneration by the redox couple and discuss the implications of this conclusion for strategies to optimize device performance. PMID:16852549

Green, Alex N M; Palomares, Emilio; Haque, Saif A; Kroon, Jan M; Durrant, James R

2005-06-30

251

Photovoltaic efficiency on dye-sensitized solar cells (DSSC) assembled using Ga-incorporated TiO 2 materials  

Microsoft Academic Search

This study examined the photoelectric conversion efficiency of DSSC (dye-sensitized solar cell) when nanometer sized Ga (0.25, 0.50, and 1.00mol%)–TiO2 prepared using a hydrothermal method was employed as a working electrode material. The particle sizes observed in the transmission electron microscopy images were <20nm in all samples. However, with increasing Ga concentration, the size increased and the shapes transformed to

Jinho Chae; Dong Young Kim; Sujung Kim; Misook Kang

2010-01-01

252

Sub-Nanometer Conformal TiO2 Blocking Layer for High Efficiency Solid-State Perovskite Absorber Solar Cells.  

PubMed

A mere 2 nm conformal titanium dioxide overlayer coated by atomic layer deposition is shown to act as a blocking layer for high-efficiency solid-state perovskite (CH3 NH3 PbI3 ) absorber-based solar cells. Surpassing the existing multilayer passivation, this ultrathin sub-nanometer layer leads to a photovoltaic power conversion efficiency of 11.5%. PMID:24804647

Chandiran, Aravind Kumar; Yella, Aswani; Mayer, Matthew T; Gao, Peng; Nazeeruddin, Mohammad Khaja; Grätzel, Michael

2014-07-01

253

PbS quantum dot sensitized anatase TiO2 nanocorals for quantum dot-sensitized solar cell applications.  

PubMed

Lead sulphide (PbS) quantum dot (QD) sensitized anatase TiO(2) nanocorals (TNC) were synthesized by SILAR and hydrothermal techniques. The TNC, PbS and PbS-TNC samples were characterized by optical absorption, XRD, FT-IR, FESEM and XPS. The results show that PbS QDs are coated on the TNCs, the optical absorption is found to be enhanced and the band edge is shifted to ~693 nm as compared with plain TNCs at 340 nm. The PbS-TNC sample exhibits an improved photoelectrochemical performance with a maximum short circuit current (J(sc)) of 3.84 mA cm(-2). The photocurrent density was found to be enhanced 2 fold, as compared with those of the bare PbS photoelectrode. The total power conversion efficiency of the PbS-TNC electrodes is 1.23%. PMID:22491525

Mali, Sawanta S; Desai, Shital K; Kalagi, Smita S; Betty, Chirayath A; Bhosale, Popatrao N; Devan, Rupesh S; Ma, Yuan-Ron R; Patil, Pramod S

2012-05-28

254

Enhanced efficiency of TIO2 photoanodes modified with WO3?x nanomaterials in dye-sensitized solar cells  

Microsoft Academic Search

In the present study, non-stoichiometric tungsten oxide (WO3-x) nanomaterials synthesized by a modified plasma arc gas condensation technique were added into anatase titanium oxide (a-TiO2) which was used as photoanode materials in dye-sensitized solar cells (DSSC). The WO3-x\\/a-TiO2 sample was characterized by FESEM, XRD, HRTEM, XPS and UV-visible spectra techniques. The photovoltaic efficiency of the DSSC fabricated by WO3-x\\/a-TiO2 was

Hsuan-Ching Lin; Huei-Siou Chen; Cherng-Yuh Su; Chaochin Su

2009-01-01

255

Self-assembled nanoscale architecture of TiO2 and application for dye-sensitized solar cells  

PubMed Central

A single-crystal-like titania nanowire network was successfully synthesized by a surfactant assisted “oriented attachment” mechanism. Highly crystallized titania nanorods have been synthesized by hydrothermal process using block-copolymer F127 with ethylenediamine. It was observed from high resolution TEM image that titanium atoms aligned perfectly in titania anatase structure with no defect. A high light-to-electricity conversion yield (9.3%) was attained by applying these titania nanoscale materials for making an electrode of dye-sensitized solar cells.

Adachi, Motonari; Jiu, Jinting; Isoda, Seiji; Mori, Yasushige; Uchida, Fumio

2008-01-01

256

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

257

Negative Ames-test of cis-di(thiocyanato)- N, N'-bis(4,4'-dicarboxy-2,2'-bipyridine)Ru(II), the sensitizer dye of the nanocrystalline TiO 2 solar cell  

Microsoft Academic Search

Dye-sensitized nanocrystalline TiO2 solar cells are currently under development. Since these cells contain an electrolyte solution we reviewed the health and safety aspects in view of indoor applications, where personal contact cannot be excluded. Only small amounts of chemicals are present in each cell and so there is no danger of acute toxicity. However, long-term effects often can be caused

J. G. de Vries; B. J. R. Scholtens; I. Maes; M. Grätzel; S. Winkel; S. Burnside; M. Wolf; A. Hinsch; J. M. Kroon; M. Ahlse; F. Tjerneld; G. Ferrero; E. Bruno; A. Hagfeldt; C. Bradbury; P. Carlsson; H. Pettersson; C. M. Verspeek-Rip; I. C. Enninga

2000-01-01

258

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

PubMed

First-principles computer simulations can contribute to a deeper understanding of the dye/semiconductor interface lying at the heart of Dye-sensitized Solar Cells (DSCs). Here, we present the results of simulation of dye adsorption onto TiO(2) surfaces, and of their implications for the functioning of the corresponding solar cells. We propose an integrated strategy which combines FT-IR measurements with DFT calculations to individuate the energetically favorable TiO(2) adsorption mode of acetic acid, as a meaningful model for realistic organic dyes. Although we found a sizable variability in the relative stability of the considered adsorption modes with the model system and the method, a bridged bidentate structure was found to closely match the FT-IR frequency pattern, also being calculated as the most stable adsorption mode by calculations in solution. This adsorption mode was found to be the most stable binding also for realistic organic dyes bearing cyanoacrylic anchoring groups, while for a rhodanine-3-acetic acid anchoring group, an undissociated monodentate adsorption mode was found to be of comparable stability. The structural differences induced by the different anchoring groups were related to the different electron injection/recombination with oxidized dye properties which were experimentally assessed for the two classes of dyes. A stronger coupling and a possibly faster electron injection were also calculated for the bridged bidentate mode. We then investigated the adsorption mode and I(2) binding of prototype organic dyes. Car-Parrinello molecular dynamics and geometry optimizations were performed for two coumarin dyes differing by the length of the ?-bridge separating the donor and acceptor moieties. We related the decreasing distance of the carbonylic oxygen from the titania to an increased I(2) concentration in proximity of the oxide surface, which might account for the different observed photovoltaic performances. The interplay between theory/simulation and experiments appears to be the key to further DSCs progress, both concerning the design of new dye sensitizers and their interaction with the semiconductor and with the solution environment and/or an electrolyte upon adsorption onto the semiconductor. PMID:23108504

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

2012-12-14

259

Deposition of a thin film of TiOx from a titanium metal target as novel blocking layers at conducting glass/TiO2 interfaces in ionic liquid mesoscopic TiO2 dye-sensitized solar cells.  

PubMed

In dye-sensitized TiO2 solar cells, charge recombination processes at interfaces between fluorine-doped tin oxide (FTO), TiO2, dye, and electrolyte play an important role in limiting the photon-to-electron conversion efficiency. From this point of view, a high work function material such as titanium deposited by sputtering on FTO has been investigated as an effective blocking layer for preventing electron leakage from FTO without influencing electron injection. X-ray photoelectron spectroscopy analysis indicates that different species of Ti (Ti4+, Ti3+, Ti2+, and a small amount of Ti0) exist on FTO. Electrochemical and photoelectrochemical measurements reveal that thin films of titanium species, expressed as TiOx, work as a compact blocking layer between FTO and TiO2 nanocrystaline film, improving Voc and the fill factor, finally giving a better conversion efficiency for dye-sensitized TiO2 solar cells with ionic liquid electrolytes. PMID:17165966

Xia, Jiangbin; Masaki, Naruhiko; Jiang, Kejian; Yanagida, Shozo

2006-12-21

260

Influences of deposition and post-annealing temperatures on properties of TiO 2 blocking layer prepared by spray pyrolysis for solid-state dye-sensitized solar cells  

Microsoft Academic Search

Influences of the temperature (Ts) for spray pyrolysis deposition of TiO2 blocking layer (BL) using titanium diisopropoxide bis(acetylacetonate) (TAA) as a precursor and the temperature (Tp) for post-annealing of the BL films on the resulting BL film morphology and photovoltaic performance of solid-state dye-sensitized solar cells (SDSC) are investigated. A Ts ranging from 300 to 400°C is found preferable for

Changyun Jiang; Man Yin Leung; Wei Ling Koh; Yuning Li

2011-01-01

261

Preparation of multilayered CdSe quantum dot sensitizers by electrostatic layer-by-layer assembly and a series of post-treatments toward efficient quantum dot-sensitized mesoporous TiO2 solar cells.  

PubMed

A multilayer of CdSe quantum dots (QDs) was prepared on the mesoporous surface of a nanoparticulate TiO(2) film by a layer-by-layer (LBL) assembly using the electrostatic interaction of the oppositely charged QD surface for application as a sensitizer in QD-sensitized TiO(2) solar cells. To maximize the absorption of incident light and the generation of excitons by CdSe QDs within a fixed thickness of TiO(2) film, the experimental conditions of QD deposition were optimized by controlling the concentration of salt added into the QD-dissolved solutions and repeating the LBL deposition a few times. A proper concentration of salt was found to be critical in providing a deep penetration of QDs into the mesopore, thus leading to a dense and uniform distribution throughout the whole TiO(2) matrix while anchoring the oppositely charged QDs alternately in a controllable way. A series of post-treatments with (1) CdCl(2), (2) thermal annealing, and (3) ZnS-coating was found to be very critical in improving the overall photovoltaic properties, presumably through a better connection between QDs, effective passivation of QD's surface, and a high impedance of recombination, which were proved by transmission electron microscopy (TEM) and electrochemical impedance spectroscopy (EIS) experiments. With a proper post-treatment of multilayered QDs as a sensitizer, the overall power conversion efficiency in the CdSe QD-sensitized TiO(2) solar cells could reach 1.9% under standard illumination condition of simulated AM 1.5G (100 mW/cm(2)). PMID:22380945

Jin, Ho; Choi, Sukyung; Velu, Ranganathan; Kim, Sungjee; Lee, Hyo Joong

2012-03-27

262

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 (V(OC)), short-circuit current (J(SC)), and photoelectric conversion efficiency (?), were investigated under the illumination of a solar simulator. As a result, all of the EQE, V(OC), J(SC), 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

2013-11-14

263

Avoiding diffusion limitations in cobalt(III/II)-tris(2,2'-bipyridine)-based dye-sensitized solar cells by tuning the mesoporous TiO2 film properties.  

PubMed

Dye-sensitized solar cells based on electrolytes containing cobalt complexes as redox shuttles typically suffer a major limitation in terms of slow diffusion of those couples through the mesoporous TiO(2) film. This results in a drop of the photocurrent density, particularly at high incident light intensities, reducing the overall cell performance. This work illustrates how tuning the four characteristic parameters of the mesoporous TiO(2) layer, namely film thickness, particle size, pore size and porosity, by simply optimizing the TiCl(4) post-treatment, completely eliminates diffusion problems of cobalt(III/II) tris(2,2'-bipyridine) and at the same time maximizes the short-circuit photocurrent density. As a result, a power conversion efficiency of 10.0% at AM 1.5 G 100 mW cm(-2) was reached in conjunction with an organic sensitizer. PMID:22855412

Tsao, Hoi Nok; Comte, Pascal; Yi, Chenyi; Grätzel, Michael

2012-08-27

264

Nitrogen-doped TiO2 nano-crystal colloid: A printable “Ink” for potential solar energy devices  

Microsoft Academic Search

Nitrogen-doped TiO2 (TiO2-xNx) is a promising semiconductor for potential applications in photocatalysis and dye sensitized solar cell (DSSC). However, one of the key challenges for this material is fabricating thin film devices using cost-effective and time-saving routes. To tackle this issue, we have developed a simple one-step, low temperature method for synthesising mono-dispersed colloids of TiO2-xNx. nano-crystals. The formed colloids

Zheng Jiang; Huahong Shi; Guidong Yang; Tiancun Xiao; M. O. Jones; P. P. Edwards

2010-01-01

265

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

266

Quantum dot PbS0.9Se0.1/TiO2 heterojunction solar cells  

NASA Astrophysics Data System (ADS)

We report on photovoltaic cells based on ternary PbS0.9Se0.1 quantum dots utilizing a heterojunction type device configuration. The best device shows an AM 1.5 power conversion efficiency of 4.25%. Furthermore, this ternary PbSxSe1-x quantum dot heterojunction device has a peak external quantum efficiency above 100% at 2.76 eV, approximately 2.7 × the bandgap energy. The ternary quantum dots combine the higher short circuit currents of the binary PbSe system with the higher open circuit voltages of the binary PbS system.

Zhai, Guangmei; Church, Carena P.; Breeze, Alison J.; Zhang, Daoli; Alers, Glenn B.; Carter, Sue A.

2012-10-01

267

Elementary photoelectronic processes at a porphyrin dye/single-walled TiO2 nanotube hetero-interface in dye-sensitized solar cells: a first-principles study.  

PubMed

A unique one-dimensional (1D) sandwich single-walled TiO2 nanotube (STNT) is proposed as a photoanode nanomaterial with perfect morphology and large specific surface area. We have thoroughly examined the elementary photoelectronic processes occurring at the porphyrin dye/STNT hetero-interface in dye-sensitized solar cells (DSSCs) by theoretical simulation. It is desirable to investigate the interfacial photoelectronic processes to elucidate the electron transfer and transport mechanism in 1D STNT-based DSSCs. We have found that the photoexcitation and interfacial charge separation mechanism can be described as follows. A ground-state electron of the dye molecule (localized around the electron donor) is first promoted to the excited state (distributed electron donor), and then undergoes ultrafast injection into the conduction band of the STNT, leaving a hole around the oxidized dye. Significantly, the injected electron in the conduction band is transported along the STNT by means of Ti 3d?(x2-y2) orbitals, offering a unidirectional electron pathway toward the electrode for massive collection without the observation of trap states. Our study not only provides theoretical guidelines for the modification of TiO2 nanotubes as a photoanode material, but also opens a new perspective for the development of a novel class of TiO2 nanotubes with high power-generation efficiency. PMID:23765451

Dong, Cunku; Li, Xin; Zhao, Wei; Jin, Pengfei; Fan, Xiujuan; Qi, Jingyao

2013-07-22

268

DFT investigation of the TiO 2 band shift by nitrogen-containing heterocycle adsorption and implications on dye-sensitized solar cell performance  

Microsoft Academic Search

A density functional theory (DFT) method (periodic DMol3) with full geometry optimization was used to investigate the adsorption of nitrogen-containing heterocycles such as 4-t-butylpyridine (TBP) and imidazole on a TiO2 anatase (101) surface. Negative shifts of the TiO2 Fermi level by N-containing heterocycle adsorption were observed. Imidazole adsorption shifted the Fermi level of TiO2 more negatively than TBP. This shift

Hitoshi Kusama; Hideo Orita; Hideki Sugihara

2008-01-01

269

Rapid thermal melted TiO 2 nano-particles into ZnO nano-rod and its application for dye sensitized solar cells  

Microsoft Academic Search

TiO2 nano-particles with an anchored ZnO nano-rod structure were synthesized using the hydrothermal method to grow ZnO nano-rods and coated TiO2 nano-particles on ZnO nano-rods using the rapid thermal annealing method on ITO conducting glass pre-coated with nano porous TiO2 film. The XRD study showed that there was little difference in crystal composition for various types of TiO2 nano-particles anchored

Ching-Hsun Chao; Chi-Lung Chang; Chien-Hung Chan; Shui-Yang Lien; Ko-Wei Weng; Kuo-Shan Yao

2010-01-01

270

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

271

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

272

Fabrication and performance of a monolithic dye-sensitized TiO2\\/Cu(In,Ga)Se2 thin film tandem solar cell  

Microsoft Academic Search

Tandem solar cells using different bandgap absorbers allow efficient photovoltaic conversion in a wide range of the solar spectrum. The optical gaps of the dye-sensitized solar cell and the Cu(In,Ga)Se2 solar cell are ideal for application in double-junction devices and a mechanically stacked device has been reported recently. We report on the monolithic integration of these subcells to cut optical

Sophie Wenger; Sieghard Seyrling; Ayodhya N. Tiwari; Michael Grätzel

2009-01-01

273

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

NASA Astrophysics Data System (ADS)

TiO2 nanomaterial with typical anatase was prepared by hydrothermal method. A surface modification method was carried out by dip TiO2 electrode into Cr(NO3)3 solution. The TiO2/Cr2O3 thin film was characterized by X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM). The current-voltage (I-V) curve revealed that short circuit current and photoelectric transfer efficiency of the modified electrode enhanced by 19.3% and 21%, respectively. The main features of electrochemical impedance spectroscopy (EIS) were discussed in a wide range of potential applied. The parameters of electron transport resistance in TiO2 film (Rw), the overall charge transfer resistance (Rct) and capacitance (Cfilm) of film were analyzed using an equivalent circuit. It was found that Rw, Rct and Cfilm switch to exponential behavior at high bias.

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

2013-09-01

274

Constructing hierarchical fastener-like spheres from anatase TiO2 nanosheets with exposed {001} facets for high-performance dye-sensitized solar cells  

NASA Astrophysics Data System (ADS)

Hierarchical fastener-like spheres assembled from anatase TiO2 nanosheets with exposed {001} facets are successfully synthesized via a facile one-pot hydrothermal process. Compared with standard commercial P25, the as-obtained hierarchical fastener-like TiO2 spheres exhibit an improved light harvesting efficiency, owing to the excellent light scattering effect of layer-by-layer hierarchical structure and superior dye adsorption capacity of the dominant {001} facets. As a consequence, the photoanode composed of TiO2 fastener-like sphere scattering layer shows an improved DSSCs conversion efficiency of 7.01% compared to that of commercial P25 (5.78%). The remarkable electrochemical performances of hierarchical fastener-like TiO2 spheres indicate their promising application as scattering materials for DSSCs.

Sun, Weiwei; Sun, Kang; Peng, Tao; You, Sujian; Liu, Haiming; Liang, Liangliang; Guo, Shishang; Zhao, Xing-Zhong

275

Improved conversion efficiency of Ag2S quantum dot-sensitized solar cells based on TiO2 nanotubes with a ZnO recombination barrier layer.  

PubMed

We improve the conversion efficiency of Ag2S quantum dot (QD)-sensitized TiO2 nanotube-array electrodes by chemically depositing ZnO recombination barrier layer on plain TiO2 nanotube-array electrodes. The optical properties, structural properties, compositional analysis, and photoelectrochemistry properties of prepared electrodes have been investigated. It is found that for the prepared electrodes, with increasing the cycles of Ag2S deposition, the photocurrent density and the conversion efficiency increase. In addition, as compared to the Ag2S QD-sensitized TiO2 nanotube-array electrode without the ZnO layers, the conversion efficiency of the electrode with the ZnO layers increases significantly due to the formation of efficient recombination layer between the TiO2 nanotube array and electrolyte. PMID:21777458

Chen, Chong; Xie, Yi; Ali, Ghafar; Yoo, Seung Hwa; Cho, Sung Oh

2011-01-01

276

Improved conversion efficiency of Ag2S quantum dot-sensitized solar cells based on TiO2 nanotubes with a ZnO recombination barrier layer  

PubMed Central

We improve the conversion efficiency of Ag2S quantum dot (QD)-sensitized TiO2 nanotube-array electrodes by chemically depositing ZnO recombination barrier layer on plain TiO2 nanotube-array electrodes. The optical properties, structural properties, compositional analysis, and photoelectrochemistry properties of prepared electrodes have been investigated. It is found that for the prepared electrodes, with increasing the cycles of Ag2S deposition, the photocurrent density and the conversion efficiency increase. In addition, as compared to the Ag2S QD-sensitized TiO2 nanotube-array electrode without the ZnO layers, the conversion efficiency of the electrode with the ZnO layers increases significantly due to the formation of efficient recombination layer between the TiO2 nanotube array and electrolyte.

2011-01-01

277

Porous TiO 2 thin films synthesized by a spray pyrolysis deposition (SPD) technique and their application to dye-sensitized solar cells  

Microsoft Academic Search

Titanium dioxide (TiO2) thin films were synthesized on glass substrates from titanium(IV)oxy acetylacetonate 2-butanol solution by a spray pyrolysis deposition (SPD) technique. The films consisted of TiO2 leaflets and showed the oriented growth along the (200) direction. The surface area of the film was successfully increased by adding a small amount of aluminum(III) acetylacetonate (AA) in the source solution. This

Masayuki Okuya; Koji Nakade; Shoji Kaneko

2002-01-01

278

Interconnected TiO2 nanowires consisting of nanosized crystallites for high conversion efficiency in dye-sensitized solar cells with gel electrolyte  

NASA Astrophysics Data System (ADS)

In this paper, we present a method to prepare interconnected TiO2 nanowires consisting of nanosized crystallites (INCNCs). A high light-to-electricity conversion yield of 8.20% was achieved by applying the structure of the thin INCNCs electrode film in DSSC with gel electrolyte, much higher than 6.84% of TiO2 nanoparticulate film with same thickness (6.5 ?m).

Wang, Juangang; Chen, Tiedan

2014-12-01

279

A nano-porous TiO 2 thin film coating method for dye sensitized solar cells (DSSCs) using electrostatic spraying with dye solution  

Microsoft Academic Search

The dye coloring process on a nano-porous TiO2 thin film for DSSCs was studied using an electrostatic spraying (ESS) method. In this study, dye coating experiments were performed using homemade ESS equipment. The coating patterns on the TiO2 thin film are changed by adjusting the applied voltages of the ESS system. The geometry of the coating patterns is observed by

Ji-Tae Hong; Hyunwoong Seo; Dong-Gil Lee; Jin-Ju Jang; Tae-Pung An; Hee-Je Kim

2010-01-01

280

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

281

Low temperature chemically synthesized rutile TiO2 photoanodes with high electron lifetime for organic dye-sensitized solar cells.  

PubMed

Electron lifetime in mesoporous nanostructured rutile TiO2 photoanodes, synthesized via a simple, cost-effective, low temperature (50-55 °C) wet chemical process, annealed at 350 °C for 1 h and not employing any sprayed TiO2 compact layer, was successfully tailored with 0.2 mM TiCl4 surface treatment that resulted in light to electric power conversion efficiency up to 4.4%. PMID:23459589

Ambade, Swapnil B; Ambade, Rohan B; Mane, Rajaram S; Lee, Go-Woon; Shaikh, ShoyebMohamad F; Patil, Supriya A; Joo, Oh-Shim; Han, Sung-Hwan; Lee, Soo-Hyoung

2013-04-11

282

Chemical bath deposition of CdS quantum dots onto mesoscopic TiO2 films for application in quantum-dot-sensitized solar cells  

Microsoft Academic Search

Alcohol, instead of water, was used as a solvent in a chemical bath deposition process for the in situ synthesis of CdS quantum dots onto mesoporous TiO2 films. Due to low surface tension, the alcohol solutions have high wettability and superior penetration ability on the mesoscopic TiO2 film, leading to a well-covered CdS on the surface of mesopores. The CdS-sensitized

Chi-Hsiu Chang; Yuh-Lang Lee

2007-01-01

283

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

PubMed

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

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

2013-06-12

284

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

2013-11-01

285

Nanoscale connectivity in a TiO2/CdSe quantum dots/functionalized graphene oxide nanosheets/Au nanoparticles composite for enhanced photoelectrochemical solar cell performance.  

PubMed

Electron transfer dynamics in a photoactive coating made of CdSe quantum dots (QDs) and Au nanoparticles (NPs) tethered to a framework of ionic liquid functionalized graphene oxide (FGO) nanosheets and mesoporous titania (TiO(2)) was studied. High resolution transmission electron microscopy analyses on TiO(2)/CdSe/FGO/Au not only revealed the linker mediated binding of CdSe QDs with TiO(2) but also, surprisingly, revealed a nanoscale connectivity between CdSe QDs, Au NPs and TiO(2) with FGO nanosheets, achieved by a simple solution processing method. Time resolved fluorescence decay experiments coupled with the systematic quenching of CdSe emission by Au NPs or FGO nanosheets or by a combination of the latter two provide concrete evidences favoring the most likely pathway of ultrafast decay of excited CdSe in the composite to be a relay mechanism. A balance between energetics and kinetics of the system is realized by alignment of conduction band edges, whereby, CdSe QDs inject photogenerated electrons into the conduction band of TiO(2), from where, electrons are promptly transferred to FGO nanosheets and then through Au NPs to the current collector. Conductive-atomic force microscopy also provided a direct correlation between the local nanostructure and the enhanced ability of composite to conduct electrons. Point contact I-V measurements and average photoconductivity results demonstrated the current distribution as well as the population of conducting domains to be uniform across the TiO(2)/CdSe/FGO/Au composite, thus validating the higher photocurrent generation. A six-fold enhancement in photocurrent and a 100 mV increment in photovoltage combined with an incident photon to current conversion efficiency of 27%, achieved in the composite, compared to the inferior performance of the TiO(2)/CdSe/Au composite imply that FGO nanosheets and Au NPs work in tandem to promote charge separation and furnish less impeded pathways for electron transfer and transport. Such a hierarchical rapid electron transfer model can be adapted to other nanostructures as well, as they can favorably impact photoelectrochemical performance. PMID:22108634

Narayanan, Remya; Deepa, Melepurath; Srivastava, Avanish Kumar

2012-01-14

286

DNA mediated wire-like clusters of self-assembled TiO2 nanomaterials: supercapacitor and dye sensitized solar cell applications.  

PubMed

A new route for the formation of wire-like clusters of TiO2 nanomaterials self-assembled in DNA scaffold within an hour of reaction time is reported. TiO2 nanomaterials are synthesized by the reaction of titanium-isopropoxide with ethanol and water in the presence of DNA under continuous stirring and heating at 60 °C. The individual size of the TiO2 NPs self-assembled in DNA and the diameter of the wires can be tuned by controlling the DNA to Ti-salt molar ratios and other reaction parameters. The eventual diameter of the individual particles varies between 15 ± 5 nm ranges, whereas the length of the nanowires varies in the 2-3 ?m range. The synthesized wire-like DNA-TiO2 nanomaterials are excellent materials for electrochemical supercapacitor and DSSC applications. From the electrochemical supercapacitor experiment, it was found that the TiO2 nanomaterials showed different specific capacitance (Cs) values for the various nanowires, and the order of Cs values are as follows: wire-like clusters (small size) > wire-like clusters (large size). The highest Cs of 2.69 F g(-1) was observed for TiO2 having wire-like structure with small sizes. The study of the long term cycling stability of wire-like clusters (small size) electrode were shown to be stable, retaining ca. 80% of the initial specific capacitance, even after 5000 cycles. The potentiality of the DNA-TiO2 nanomaterials was also tested in photo-voltaic applications and the observed efficiency was found higher in the case of wire-like TiO2 nanostructures with larger sizes compared to smaller sizes. In future, the described method can be extended for the synthesis of other oxide based materials on DNA scaffold and can be further used in other applications like sensors, Li-ion battery materials or treatment for environmental waste water. PMID:24905088

Nithiyanantham, U; Ramadoss, Ananthakumar; Ede, Sivasankara Rao; Kundu, Subrata

2014-06-26

287

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

PubMed

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

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

2014-07-01

288

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

PubMed Central

TiO2 hierarchical nanostructures with secondary growth have been successfully synthesized on electrospun nanofibers via surfactant-free hydrothermal route. The effect of hydrothermal reaction time on the secondary nanostructures has been studied. The synthesized nanostructures comprise electrospun nanofibers which are polycrystalline with anatase phase and have single crystalline, rutile TiO2 nanorod-like structures growing on them. These secondary nanostructures have a preferential growth direction [110]. UV–vis spectroscopy measurements point to better dye loading capability and incident photon to current conversion efficiency spectra show enhanced light harvesting of the synthesized hierarchical structures. Concomitantly, the dye molecules act as spacers between the conduction band electrons of TiO2 and holes in the hole transporting medium, i.e., spiro-OMeTAD and thus enhance open circuit voltage. The charge transport and recombination effects are characterized by electrochemical impedance spectroscopy measurements. As a result of improved light harvesting, dye loading, and reduced recombination losses, the hierarchical nanofibers yield 2.14% electrochemical conversion efficiency which is 50% higher than the efficiency obtained by plain nanofibers.

2014-01-01

289

TiO2 Nanotubes with a ZnO Thin Energy Barrier for Improved Current Efficiency of CdSe Quantum-Dot-Sensitized Solar Cells  

SciTech Connect

This paper reports the formation of a thin ZnO energy barrier between a CdSe quantum dot (Q dots) sensitizer and TiO{sub 2} nanotubes (TONTs) for improved current efficiency of Q dot-sensitized solar cells. The formation of a ZnO barrier between TONTs and the Q dot sensitizer increased the short-circuit current under illumination and also reduced the dark current in a dark environment. The power conversion efficiency of Q dot-sensitized TONT solar cells increased by 25.9% in the presence of the ZnO thin layer due to improved charge-collecting efficiency and reduced recombination.

Lee, W.; Kang, S. H.; Kim, J. Y.; Kolekar, G. B.; Sung, Y. E.; Han, S. H.

2009-01-01

290

Evaluation of the combined solar TiO2/photo-Fenton process using multivariate analysis.  

PubMed

The effect of combining the photocatalytic processes using TiO2 and the photo-Fenton reaction with Fe3+ or ferrioxalate as a source of Fe2+ was investigated in the degradation of 4-chlorophenol (4CP) and dichloroacetic acid (DCA) using solar irradiation. Multivariate analysis was used to evaluate the role of three variables: iron, H2O2 and TiO2 concentrations. The results show that TiO2 plays a minor role when compared to iron and H2O2 in the solar degradation of 4CP and DCA in the studied conditions. However, its presence can improve TOC removal when H2O2 is totally consumed. Iron and peroxide play major roles, especially when Fe(NO3)3 is used in the degradation of 4CP. No significant synergistic effect was observed by the addition of TiO2 in this process. On the other hand, synergistic effects were observed between FeOx and TiO2 and between H2O2 and TiO2 in the degradation of DCA. PMID:15077971

Nogueira, R F P; Trovó, A G; Paterlini, W C

2004-01-01

291

Effect of the molecular weight of a polyethylene glycol on the photoluminescence spectra of porous TiO 2 films for dye-sensitized solar cells  

Microsoft Academic Search

Dye-sensitized solar cells (DSCs) are expected to be used for future clean energy. In general, when the titania porous electrode in DSCs is made, a polyethylene glycol (PEG) is added to obtain the porous structure. Although the conversion efficiency of the DSC became high when the high molecular weight of PEG was used, its reason was not clear. In the

K. Sakai; Y. Hirashita; T. Aihara; A. Fukuyama; T. Ikari; K. Kukita; S. Furukawa

2011-01-01

292

Electron transport and recombination in dye sensitized solar cells fabricated from obliquely sputter deposited and thermally annealed TiO 2 films  

Microsoft Academic Search

Dye sensitized solar cells based on annealed titanium dioxide films prepared by oblique reactive DC magnetron sputtering have been investigated in detail. Electron transport and recombination were studied using intensity-modulated photocurrent and photovoltage spectroscopy. Electron transport time as well as lifetime were found to increase upon lowering of the light intensity and to increase upon increasing the thickness of the

Sebastian M. Waita; Bernard O. Aduda; Julius M. Mwabora; Claes G. Granqvist; Sten-Eric Lindquist; Gunnar A. Niklasson; Anders Hagfeldt; Gerrit Boschloo

2007-01-01

293

High efficiency double heterojunction polymer photovoltaic cells using highly ordered TiO2 nanotube arrays  

NASA Astrophysics Data System (ADS)

Vertically oriented TiO2 nanotube arrays formed by anodization offer a highly ordered material architecture for efficient charge generation and collection in photoelectrochemical devices. A blend of regioregular poly(3-hexylthiophene) and a methanofullerene (phenyl C71-butyric acid methyl ester) was infiltrated into transparent TiO2 nanotube films. The heterojunction poly(3-hexylthiophene) (P3HT)-([6,6]-phenyl-C71-butyric acid methyl ester) and P3HT-TiO2 interfaces both result in charge separation. The resulting solid state solar cells show a short-circuit current density of 12.4 mA/cm2, 641 mV open circuit potential, and a 0.51 fill factor, yielding power conversion efficiencies of 4.1% under AM 1.5 sun.

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

2007-10-01

294

Polyoxometalate-anatase TiO2 composites are introduced into the photoanode of dye-sensitized solar cells to retard the recombination and increase the electron lifetime.  

PubMed

Polyoxometalate-TiO(2) composites have been successfully introduced into the photoanode of dye-sensitized solar cells to reduce the recombination of the electrons, which results in a longer electron lifetime. The performance of the cells with the polyoxometalate-modified photoanode is better than the cell with a pure P25 photoanode. The effect of the polyoxometalate was studied by electrochemical impedance spectroscopy and open-circuit voltage decay measurement. The results show that the electron lifetime becomes longer following an increase in the amount of the polyoxometalate. PMID:23314419

Wang, Shi-Ming; Liu, Lin; Chen, Wei-Lin; Wang, En-Bo; Su, Zhong-Min

2013-02-28

295

TiO 2 pore-filling and its effect on the efficiency of solid-state dye-sensitized solar cells  

Microsoft Academic Search

Solid-state dye-sensitized solar cells have been the focus of much attention over the past few years. We have recently been able to demonstrate efficiencies in excess of 4% and further improvements are expected. Here we compare a range of different hole conductor materials and investigate a number of key parameters which affect their performance. Wetting and pore-filling of the nanoporous

Lukas Schmidt-Mende; Michael Grätzel

2006-01-01

296

Poly(butyl acrylate)\\/NaI\\/I 2 electrolytes for dye-sensitized nanocrystalline TiO 2 solar cells  

Microsoft Academic Search

Solid polymer electrolytes consisting of NaI and I2 dissolved in poly(butyl acrylate) (PBA, Mw=99,000 g\\/mol) were prepared and applied to dye-sensitized solar cells (DSSC). Upon incorporation of salt, the free ester carbonyl stretching bands of PBA in FT-IR spectra shift to a lower wave number, confirming the complex formation between sodium ions and carbonyl oxygens. Coordinative interactions and structural changes

Jong Hak Kim; Moon-Sung Kanga; Young Jin Kim; Jongok Won; Yong Soo Kanga

2005-01-01

297

Stem cell attachment to layer-by-layer assembled TiO 2 nanoparticle thin films  

Microsoft Academic Search

Surface topography is one of the most important factors influencing the attachment and spreading of cells. In the present study, layer-by-layer assembled titanium dioxide (TiO2) nanoparticle thin films were chosen for attachment, proliferation and spreading studies on mouse mesenchymal stem cells (MSC). Increasing surface roughness was observed with increasing number of layer-by-layer assembled TiO2 thin films. Four layer TiO2 thin

Dinesh S. Kommireddy; Shashikanth M. Sriram; Yuri M. Lvov; David K. Mills

2006-01-01

298

Near-uv photon efficiency in a TiO2 electrode - Application to hydrogen production from solar energy  

NASA Technical Reports Server (NTRS)

An n-type (001) TiO2 electrode irradiated at 365 nm was tested under anodic polarization. A saturation current independent of pH and proportional to light intensity has been observed. Accurate measurements of the incident power lead to a 60 per cent photon efficiency. A photoelectrochemical cell built with such an electrode, operated under solar irradiation without concentration, produced an electrolysis current of 0.7 mA/sq cm without applied voltage.

Desplat, J.-L.

1976-01-01

299

First-principles study on Ru(4,4',4"-tricarboxy-2,2':6',2"-terpyridine)(NCS)3 sensitizer on TiO2 anatase(101) surface: Adsorbed structures and electronic states for dye-sensitized solar cells  

NASA Astrophysics Data System (ADS)

Dye-sensitized solar cells are expected as a cost effective solar-to-electricity energy conversion devices. The efficiency of the power conversion is greater than 10% when Ru(II) polypyridyl sensitizers are used. For further improvement of the efficiency, we need to understand the adsorbed structures at atomistic level in detail. In this study, we investigated the adsorbed structures of Ru(4,4',4"-tricarboxy-2,2':6',2"-terpyridine)(NCS)3 sensitizer on TiO2 anatase(101) surface. For four possible adsorbed structures (two candidates have one adsorbed carboxyl group(one-leg) and the others have two adsorbed groups(two-leg)), we found the adsorption energies are quite similar within 0.4 eV. This is attributed to the presence of the hydrogen bond between the hydrogen of carboxyl group and the oxygen of the surface in the one-leg structure. We also calculated the excited states of the four structures of the sensitizer by TDDFT and found that the UV spectrum shift depending on the structure differences.

Sodeyama, Keitaro; Sumita, Masato; Tateyama, Yoshitaka

2011-03-01

300

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

2013-10-21

301

Passivation of nanocrystalline TiO2 junctions by surface adsorbed phosphinate amphiphiles enhances the photovoltaic performance of dye sensitized solar cells.  

PubMed

We report a new class of molecular insulators that electronically passivate the surface of nanocrystalline titania films for high performance dye sensitized solar cells (DSC). Using electrical impedance measurements we demonstrate that co-adsorption of dineohexyl bis-(3,3-dimethyl-butyl)-phosphinic acid (DINHOP), along with the amphiphilic ruthenium sensitizer Z907Na increased substantially the power output of the cells mainly due to a retardation of interfacial recombination of photo-generated charge carriers. The use of phosphinates as anchoring groups opens up new avenues for modification of the surface by molecular insulators, sensitizers and other electro-active molecules to realize the desired optoelectronic performance of devices based on oxide junctions. PMID:19904428

Wang, Mingkui; Li, Xin; Lin, Hong; Pechy, Peter; Zakeeruddin, Shaik M; Grätzel, Michael

2009-12-01

302

Effects of TiO2 electron blocking layer on photovoltaic performance of photo-electrochemical cell  

NASA Astrophysics Data System (ADS)

Dye-sensitized solar cells (DSCs) have used transparent conductive Fluorine-doped SnO2 (FTO) glass/porous TiO2 layer attached using dye molecules/electrolytes (I-/I3-)/Platinium-coated FTO glass configuration. In this work, prior to the coating of nanoporous TiO2 layer on FTO glass, a dense layer of TiO2 film with a thickness of less than ?100 nm was deposited directly onto the FTO as an electron blocking layer by radio frequency (RF) magnetron sputtering. Under 100 mW/cm2 illumination at AM 1.5, the energy conversion efficiency (?) of the prepared DSC with electron blocking layer of 80 nm thickness was 6.9% (Voc = 0.67 V, Jsc = 12.18 mA/cm2, ff = 0.63), which is increased by 1.3% compared to the typical cell without electron blocking layer.

Bin, Jae-Wook; Kim, Doo-Hwan; Sung, Youl-Moon; Park, Min-Woo

2014-06-01

303

Synthesis, photovoltaic performances and TD-DFT modeling of push-pull diacetylide platinum complexes in TiO2 based dye-sensitized solar cells.  

PubMed

In this joint experimental-theoretical work, we present the synthesis and optical and electrochemical characterization of five new bis-acetylide platinum complex dyes end capped with diphenylpyranylidene moieties, as well as their performances in dye-sensitized solar cells (DSCs). Theoretical calculations relying on Time-Dependent Density Functional Theory (TD-DFT) and a range-separated hybrid show a very good match with experimental data and allow us to quantify the charge-transfer character of each compound. The photoconversion efficiency obtained reaches 4.7% for 8e (see TOC Graphic) with the tri-thiophene segment, which is among the highest efficiencies reported for platinum complexes in DSCs. PMID:24837848

Gauthier, Sébastien; Caro, Bertrand; Robin-Le Guen, Françoise; Bhuvanesh, Nattamai; Gladysz, John A; Wojcik, Laurianne; Le Poul, Nicolas; Planchat, Aurélien; Pellegrin, Yann; Blart, Errol; Jacquemin, Denis; Odobel, Fabrice

2014-08-01

304

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

NASA Astrophysics Data System (ADS)

We demonstrate an array of solid-state dye-sensitized solar cells (SS-DSSCs) for a high-voltage power source based on micropatterned titanium dioxide nanoparticles (TNPs) as photoanodes connected in series. The underlying concept of patterning the TNP of a few micrometers thick lies on the combination of the lift-off process of transfer-printed patterns of a sacrificial layer and the soft-cure treatment of the TNP for fixation. This sacrificial layer approach allows for high pattern fidelity and stability, and it enables to construct stable, micrometer-thick, and contamination-free TNP patterns for developing the SS-DSSC array for miniature high-voltage applications. The array of 20 SS-DSSCs integrated in series is found to show a voltage output of around 7 V.

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

2013-11-01

305

Optimization of TiO2/SiO2 Nanorod Multilayers for High Angle of Incidence Anti-Reflection Coatings for Solar Cells  

NASA Astrophysics Data System (ADS)

Conventional single-layer antireflection (AR) coatings work only at a single wavelength and at normal incidence. However, use of graded-index coatings having multi-layers yield omnidirectional, broadband antireflection characteristics. This will eliminate the need for sun tracking while maintaining high quantum efficiencies. Recent developments in growth of TiO2 and SiO2 nanostructures deposited by oblique angle deposition have shown very low refractive indices close to air. Fabry-Perot (FP) interference from the multilayer AR coating structure plays a major role in light transmitted at particular wavelengths. Depending on the thickness and refractive index of the layers, the overall reflection and transmission will get increased or reduced at certain wavelengths due to constructive and destructive interference from multiple reflections. It is possible to fine tune the thickness of each layer and the number of layers to minimize the overall reflection by enhancing destructive interference in the multilayer structure. This work demonstrates the FP oscillator behavior over a broad visible to infrared spectral range with incident angles up to 60 degrees in order to minimize the variations in the reflection and maximize the transmission up to 98.5 %.

Jayasinghe, Ranga; Unil Perera, A. G.; Zhao, Yiping

2012-03-01

306

Solar light induced and TiO 2 assisted degradation of textile dye reactive blue 4  

Microsoft Academic Search

Aqueous solutions of reactive blue 4 textile dye are totally mineralised when irradiated with TiO2 photocatalyst. A solution containing 4×10?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, SO42?, NO3?, NH4+ and H2O under solar

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

2002-01-01

307

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

PubMed Central

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

2014-01-01

308

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

PubMed Central

For conventional dye or quantum dot sensitized solar cells, which are fabricated using mesoporous films, the inefficient electron transport due to defects such as grain boundaries and surface traps is a major drawback. To simultaneously increase the carrier transport efficiency as well as the surface area, optimal-assembling of hierarchical nanostructures is an attractive approach. Here, a three dimensional (3D) hierarchical heterostructure, consisting of CdS sensitized one dimensional (1D) ZnO nanorods deposited on two dimensional (2D) TiO2 (001) nanosheet, is prepared via a solution-process method. Such heterstructure exhibits significantly enhanced photoelectric and photocatalytic H2 evolution performance compared with CdS sensitized 1D ZnO nanorods/1D TiO2 nanorods photoanode, as a result of the more efficient light harvesting over the entire visible light spectrum and the effective electron transport through a highly connected 3D network.

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

2014-01-01

309

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

PubMed

For conventional dye or quantum dot sensitized solar cells, which are fabricated using mesoporous films, the inefficient electron transport due to defects such as grain boundaries and surface traps is a major drawback. To simultaneously increase the carrier transport efficiency as well as the surface area, optimal-assembling of hierarchical nanostructures is an attractive approach. Here, a three dimensional (3D) hierarchical heterostructure, consisting of CdS sensitized one dimensional (1D) ZnO nanorods deposited on two dimensional (2D) TiO2 (001) nanosheet, is prepared via a solution-process method. Such heterstructure exhibits significantly enhanced photoelectric and photocatalytic H2 evolution performance compared with CdS sensitized 1D ZnO nanorods/1D TiO2 nanorods photoanode, as a result of the more efficient light harvesting over the entire visible light spectrum and the effective electron transport through a highly connected 3D network. PMID:25030846

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

2014-01-01

310

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

311

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

312

The induction of maturation on dendritic cells by TiO2 and Fe3O4@TiO2 nanoparticles via NF-?B signaling pathway.  

PubMed

Nanomaterials are increasingly used in many fields, including drug vectors and vaccine formulation. In this study, nano-TiO2 and magnetic Fe3O4@TiO2 were synthesized and their abilities to activate dendritic cells were investigated. The signaling pathway involved in their effects on the cellular functions was also explored. First, nano-TiO2 and Fe3O4@TiO2 were prepared with diameters of 82nm and 63nm, and zeta potentials of 41.5mV and 30.2mV, respectively. The magnetic property of Fe3O4@TiO2 was detected to be 12.9emu/g. Both kinds of nanoparticles were proved to have good biocompatibility in vitro. Second, the exposure of nano-TiO2 and Fe3O4@TiO2 caused an increased expression of TNF-?, CD86 and CD80, and besides, Fe3O4@TiO2 showed a certain up-regulation on MHC-II. The cellular uptake of Ovalbumin on BMDCs could be strongly improved by nano-TiO2 and Fe3O4@TiO2 as detected via flow cytometer and confocal observation. Further investigation revealed that nano-TiO2 and Fe3O4@TiO2 significantly increased the NF-?B expression in the nucleus, indicating that the NF-?B signaling pathway was involved in the dendritic cell maturation. Our results suggested that nano-TiO2 and Fe3O4@TiO2 may function as a useful vector to promote vaccine delivery in immune cells, and Fe3O4@TiO2 provided a possibility to deliver and track vaccines via its magnetofection. PMID:24863229

Zhu, Rongrong; Zhu, Yanjing; Zhang, Min; Xiao, Yu; Du, Xiling; Liu, Hui; Wang, Shilong

2014-06-01

313

Understanding TiO(2) size-dependent electron transport properties of a graphene-TiO(2) photoanode in dye-sensitized solar cells using conducting atomic force microscopy.  

PubMed

Conducting AFM reveals a continuous conduction network of a TiO2 -graphene composite in DSSC due to a more intimate contact between the smaller sized TiO2 -graphene composite nanosheets,which reduces the internal resistance at TiO2 /TiO2 and TiO2 /FTO interfaces and ultimately leads to a faster and more efficient electron transport in the photoanode. PMID:24114931

He, Ziming; Phan, Hung; Liu, Jing; Nguyen, Thuc-Quyen; Tan, Timothy Thatt Yang

2013-12-17

314

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

315

High-performance dye-sensitized solar cells containing double-layer organized mesoporous TiO2 films sensitized by a dye with a high molar extinction coefficient  

NASA Astrophysics Data System (ADS)

In the present work, we describe a practical technique to construct double-layer organized mesoporous TiO2 films with a combined thickness of 0.85 ?m. Large mesopores (25.74 nm) formed in the film by using ovalbumin as the main template facilitate entry and adsorption of dye molecules. The films were sensitized by a dye that exhibits a high molar extinction coefficient because it contains a ligand with a fused-ring system. The double-layer films exhibited a solar conversion efficiency of 7.37%, which was about 35% higher than that of monolayer films.

Wang, Juangang; Shang, Yunli

2013-04-01

316

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

PubMed

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

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

2013-12-15

317

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

NASA Astrophysics Data System (ADS)

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

Zelinski, Andrew

318

[TiO2-DNA nanocomposites capable of penetrating into cells].  

PubMed

Methods of noncovalent immobilization of DNA fragments onto titanium dioxide nanoparticles (TiO2) were developed, which led to TiO2-DNA nanocomposites capable of penetrating through cell membranes. TiO2 nanoparticles of different forms (amorphous, anatase, brookit) with enhanced agglomeration stability were synthesized. The particles were characterized by X-ray diffraction, small angle X-ray scattering, infrared spectroscopy and atomic force microscopy. Three approaches to the preparation of nanocomposites are described: (1) sorption of polylysine-containing oligonucleotides onto TiO2-nanoparticles, (2) the electrostatic binding of oligonucleotides to TiO2 nanoparticles bearing immobilized polylysine, and (3) sorption of oligonucleotides on TiO2 nanoparticles in the presence of cetavlon. All three methods provide an efficient and stable immobilization of DNA fragments onto nanoparticles, which leads to nanocomposites with a density for an oligonucleotide up to 40 nmol/mg. It is shown that DNA fragments in nanocomposites retain their ability to form complementary complexes and can be delivered into cells without transfection agents and other methods of exposure. PMID:23844510

Levina, A S; Ismagilova, Z R; Repkova, M N; Shikina, N V; Ba?borodin, S I; Shatskaia, N V; Zagrebel'ny?, S N; Zarytova, V F

2013-01-01

319

Solar photocatalytic degradation of azo dye: comparison of photocatalytic efficiency of ZnO and TiO 2  

Microsoft Academic Search

The photocatalytic activity of commercial ZnO powder has been investigated and compared with that of Degussa P25 TiO2. Laboratory experiments with acid brown 14 as the model pollutant have been carried out to evaluate the performance of both ZnO and TiO2 catalysts. Solar light was used as the energy source for the photocatalytic experiments. These catalysts were examined for surface

S. Sakthivel; B. Neppolian; M. V. Shankar; B. Arabindoo; M. Palanichamy; V. Murugesan

2003-01-01

320

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

321

Stem cell attachment to layer-by-layer assembled TiO2 nanoparticle thin films.  

PubMed

Surface topography is one of the most important factors influencing the attachment and spreading of cells. In the present study, layer-by-layer assembled titanium dioxide (TiO2) nanoparticle thin films were chosen for attachment, proliferation and spreading studies on mouse mesenchymal stem cells (MSC). Increasing surface roughness was observed with increasing number of layer-by-layer assembled TiO2 thin films. Four layer TiO2 thin film showed higher number of attached cells than a one layer thin film and control surfaces. MSCs experienced no cytotoxic effects after culture on the TiO2 coated substrates as observed from the cytotoxicity tests. Cell spreading, visualized with scanning electron microscopy, showed a faster rate of spreading on a rougher surface. Cells on a four-layer substrate, at 12 h showed complete spreading, where as most of the cells on a control surface and a one-layer surface, at 24 h, retained a rounded morphology. In conclusion, TiO2 nanoparticle thin films were successfully assembled in alternation with polyelectrolytes and in-vitro studies with MSC showed an increase in the attachment and faster spreading of cells on rougher surfaces. PMID:16647115

Kommireddy, Dinesh S; Sriram, Shashikanth M; Lvov, Yuri M; Mills, David K

2006-08-01

322

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

Microsoft Academic Search

The photodegradation of two common and very stable azo-dyes, i.e. methyl-orange (C14H14N3SO3Na) and orange II (C16H11N2SO4Na), is reported. The photocatalytic oxidation was carried out in aqueous suspensions of polycrystalline TiO2 irradiated by sunlight. Compound parabolic collectors, installed at the “Plataforma Solar de Almer??a” (PSA, Spain) were used as the photoreactors and two identical reacting systems allowed to perform photoreactivity runs

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

2002-01-01

323

Photo-induced charge transfer in defect-free (TiO 2) 15 nanoparticles and charge transfer from carotenoid to (TiO 2) 15b nanoparticle in carotenoid–(TiO 2) 15b complex used for solar cell  

Microsoft Academic Search

Photo-induced charge transfer process between the carotenoids and (TiO2)15b was theoretically studied with quantum chemical methods, and the charge transfer information of the carotenoid–(TiO2)15 complex were visualized using the charge difference density method. Calculated results show the strongest absorption wavelength is located at 606nm. Electron transfer in the isolated (TiO2)15 was also analyzed in some detail. For 15b (C2v), electrons

Zhilin Yang; Yan Li; Yuanzuo Li; Maodu Chen; Junyong Kang; Liyun Gu; Fengcai Ma

2009-01-01

324

The role of fibronectin in cell adhesion to spiral patterned TiO2 nanoparticles.  

PubMed

Spiral micropatterned surfaces of decreasing dimensions were produced by photo-immobilizing a photo-reactive hyaluronan (Hyal) derivative on TiO2 nanoparticles. The microstructured surfaces were characterized by both scanning electron microscopy and atomic force microscopy analysis. The behavior, of both endothelial cells (HCAEC) and tumoral mouse fibroblasts (NIH3T3) on the patterned surfaces was evaluated. HCAEC adhered only to the TiO2 nanoparticles avoiding contact with the Hyal. NIH3T3 adhered to and completely covered the TiO2 spiral but prolonging the culture time, it also covered the external photo-immobilized Hyal surface. The role of fibronectin to mediate cell adhesion to the TiO2 pattern surfaces was evaluated by experiments with blocked fibronectin membrane receptors on both HCAEC and NIH3T3. The results showed the absence of any adhering cells. Therefore, fibronectin seemed to be the only key protein in mediating cell adhesion to these TiO2 substrates. PMID:20799170

Lamponi, Stefania; Forbicioni, Marco; Barbucci, Rolando

2009-01-01

325

Detection of TiO2 nanoparticles in cells by flow cytometry.  

PubMed

Evaluation of the potential hazard of man-made nanomaterials has been hampered by a limited ability to observe and measure nanoparticles in cells. In this study, different concentrations of TiO(2) nanoparticles were suspended in cell culture medium. The suspension was then sonicated and characterized by dynamic light scattering and microscopy. Cultured human-derived retinal pigment epithelial cells (ARPE-19) were incubated with TiO(2) nanoparticles at 0, 0.1, 0.3, 1, 3, 10, and 30 microg/ml for 24 hours. Cellular reactions to nanoparticles were evaluated using flow cytometry and dark field microscopy. A FACSCalibur flow cytometer was used to measure changes in light scatter after nanoparticle incubation. Both the side scatter and forward scatter changed substantially in response to the TiO(2). From 0.1 to 30 microg/ml TiO(2), the side scatter increased sequentially while the forward scatter decreased, presumably due to substantial light reflection by the TiO(2) particles. Based on the parameters of morphology and the calcein-AM/propidium iodide viability assay, TiO(2) concentrations below 30 microg/ml TiO(2) caused minimal cytotoxicity. Microscopic analysis was done on the same cells using an E-800 Nikon microscope containing a xenon light source and special dark field objectives. At the lowest concentrations of TiO(2) (0.1-0.3 microg/ml), the flow cytometer could detect as few as 5-10 nanoparticles per cell due to intense light scattering by TiO(2). Rings of concentrated nanoparticles were observed around the nuclei in the vicinity of the endoplasmic reticulum at higher concentrations. These data suggest that the uptake of nanoparticles within cells can be monitored with flow cytometry and confirmed by dark field microscopy. This approach may help fulfill a critical need for the scientific community to assess the relationship between nanoparticle dose and cellular toxicity Such experiments could potentially be performed more quickly and easily using the flow cytometer to measure both nanoparticle uptake and cellular health. PMID:20564539

Zucker, R M; Massaro, E J; Sanders, K M; Degn, L L; Boyes, W K

2010-07-01

326

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

NASA Astrophysics Data System (ADS)

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

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

2014-06-01

327

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

PubMed

Composite WO3/TiO2 nanostructures with optimal properties that enhance solar photoconversion reactions were developed, characterized, and tested. The TiO2 nanotubes were prepared by anodization of Ti foil and used as substrates for WO3 electrodeposition. The WO3 electrodeposition parameters were controlled to develop unique WO3 nanostructures with enhanced photoelectrochemical properties. Scanning electron microscopy (SEM) images showed that the nanomaterials with optimal photocurrent density have the same ordered structure as TiO2 nanotubes, with an external tubular nanostructured WO3 layer. Diffuse reflectance spectra showed an increase in the visible absorption relative to bare TiO2 nanotubes and in the UV absorption relative to bare WO3 films. Incident simulated solar photon-to-current efficiency (IPCE) increased from 30% (for bare WO3) to 50% (for tubular WO3/TiO2 composites). With the addition of diverse organic pollutants, the photocurrent densities exhibited more than a 5-fold increase. Chemical oxygen demand measurements showed the simultaneous photodegradation of organic pollutants. The results of this work showed that the unique structure and composition of these composite WO3/TiO2 materials enhance the IPCE efficiencies, optical properties, and photodegradation performance compared with the parent materials. PMID:24195676

Reyes-Gil, Karla R; Robinson, David B

2013-12-11

328

Photoinactivation of Escherichia coli by sulfur-doped and nitrogen-fluorine-codoped TiO2 nanoparticles under solar simulated light and visible light irradiation.  

PubMed

Titanium dioxide (TiO2) is one of the most widely used photocatalysts for the degradation of organic contaminants in water and air. Visible light (VL) activated sulfur-doped TiO2 (S-TiO2) and nitrogen-fluorine-codoped TiO2 (N-F-TiO2) were synthesized by sol-gel methods and characterized. Their photoinactivation performance was tested against Escherichia coli under solar simulated light (SSL) and VL irradiation with comparison to commercially available TiO2. Undoped Degussa-Evonik P-25 (P-25) and Sigma-TiO2 showed the highest photocatalytic activity toward E. coli inactivation under SSL irradiation, while S-TiO2 showed a moderate toxicity. After VL irradiation, Sigma-TiO2 showed higher photoinactivation, whereas S-TiO2 and P-25 showed moderate toxicity. Oxidative stress to E. coli occurred via formation of hydroxyl radicals leading to lipid peroxidation as the primary mechanism of bacterial inactivation. Various other biological models, including human keratinocytes (HaCaT), zebrafish liver cells (ZFL), and zebrafish embryos were also used to study the toxicity of TiO2 NPs. In conclusion, N-F-TiO2 did not show any toxicity based on the assay results from all the biological models used in this study, whereas S-TiO2 was toxic to zebrafish embryos under all the test conditions. These findings also demonstrate that the tested TiO2 nanoparticles do not show any adverse effects in HaCaT and ZFL cells. PMID:23906338

Pathakoti, Kavitha; Morrow, Shavonda; Han, Changseok; Pelaez, Miguel; He, Xiaojia; Dionysiou, Dionysios D; Hwang, Huey-Min

2013-09-01

329

Nanoscale TiO2 and Fe2O3 Architectures for Solar Energy Conversion Schemes  

NASA Astrophysics Data System (ADS)

The direct conversion of sunlight into more useable forms of energy has the potential of alleviating the environmental and social problems associated with a dependence on fossil fuels. If solar energy is to be utilized en-masse, however, it must be inexpensive and widely available. In this vein, the focus of this thesis is on nanostructured materials relevant to solar energy conversion and storage. Specifically, this thesis describes the ambient sol-gel synthesis of titanium dioxide (Ti02) nanowires designed for enhanced charge-transfer in solar collection devices, and the synthesis of novel disordered metal-oxide (MOx) catalysts for water oxidation. The introductory chapter of this thesis gives an overview of the various approaches to solar energy conversion. Sol---gel reaction conditions that enable the growth of one-dimensional (1-D) anatase TiO2 nanostructures from fluorine-doped tin oxide (FTO) for photovoltaics (PVs) are described in the second chapter. The generation of these linear nanostructures in the absence of an external bias or template is achieved by using facile experimental conditions (e.g., acetic acid (HOAc) and titanium isopropoxide (Ti(OiPr)4) in anhydrous heptane). The procedure was developed by functionalizing base-treated substrates with Ti-oxide nucleation sites that serve as a foundation for the growth of linear Ti-oxide macromolecules, which upon calcination, render uniform films of randomly oriented anatase TiO2 nanowires. A systematic evaluation of how reaction conditions (e.g., solvent volume, stoichiometry of reagents, substrate base treatment) affect the generation of these TiO 2 films is presented. A photo-organic MO. deposition route (i.e., photochemical metal-organic deposition (PMOD)) used to deposit thin-films of amorphous iron oxide (a-Fe2O3) for water oxidation catalysis is detailed in third chapter. It is shown that the irradiation of a spin-coated metal-organic film produces a film of non-crystalline a-Fe203. It is shown that annealing at various temperatures produces a-Fe 2O3 films with variable electronic properties and catalytic activities in the context of water oxidation. The study revealed that a-Fe2O3 are superior water oxidation catalysts (WOCs) relative to crystalline forms produced by high temperature annealing of the thin-films. This research has important implications in the conversion of sunlight into electricity, and then into hydrogen fuels.

Sedach, Pavel Anatolyvich

330

Nanometer-thin TiO2 enhances skeletal muscle cell phenotype and behavior  

PubMed Central

Background The independent role of the surface chemistry of titanium in determining its biological properties is yet to be determined. Although titanium implants are often in contact with muscle tissue, the interaction of muscle cells with titanium is largely unknown. This study tested the hypotheses that the surface chemistry of clinically established microroughened titanium surfaces could be controllably varied by coating with a minimally thin layer of TiO2 (ideally pico-to-nanometer in thickness) without altering the existing topographical and roughness features, and that the change in superficial chemistry of titanium is effective in improving the biological properties of titanium. Methods and results Acid-etched microroughened titanium surfaces were coated with TiO2 using slow-rate sputter deposition of molten TiO2 nanoparticles. A TiO2 coating of 300 pm to 6.3 nm increased the surface oxygen on the titanium substrates in a controllable manner, but did not alter the existing microscale architecture and roughness of the substrates. Cells derived from rat skeletal muscles showed increased attachment, spread, adhesion strength, proliferation, gene expression, and collagen production at the initial and early stage of culture on 6.3 nm thick TiO2-coated microroughened titanium surfaces compared with uncoated titanium surfaces. Conclusion Using an exemplary slow-rate sputter deposition technique of molten TiO2 nanoparticles, this study demonstrated that titanium substrates, even with microscale roughness, can be sufficiently chemically modified to enhance their biological properties without altering the existing microscale morphology. The controllable and exclusive chemical modification technique presented in this study may open a new avenue for surface modifications of titanium-based biomaterials for better cell and tissue affinity and reaction.

Ishizaki, Ken; Sugita, Yoshihiko; Iwasa, Fuminori; Minamikawa, Hajime; Ueno, Takeshi; Yamada, Masahiro; Suzuki, Takeo; Ogawa, Takahiro

2011-01-01

331

Superiority of solar Fenton oxidation over TiO2 photocatalysis for the degradation of trimethoprim in secondary treated effluents.  

PubMed

The overall aim of this work was to examine the degradation of trimethoprim (TMP), which is an antibacterial agent, during the application of two advanced oxidation process (AOP) systems in secondary treated domestic effluents. The homogeneous solar Fenton process (hv/Fe(2+)/H2O2) and heterogeneous photocatalysis with titanium dioxide (TiO2) suspensions were tested. It was found that the degradation of TMP depends on several parameters such as the amount of iron salt and H2O2, concentration of TiO2, pH of solution, solar irradiation, temperature and initial substrate concentration. The optimum dosages of Fe(2+) and H2O2 for homogeneous ([Fe(2+)] = 5 mg L(-1), [H2O2] = 3.062 mmol L(-1)) and TiO2 ([TiO2] = 3 g L(-1)) for heterogeneous photocatalysis were established. The study indicated that the degradation of TMP during the solar Fenton process is described by a pseudo-first-order reaction and the substrate degradation during the heterogeneous photocatalysis by the Langmuir-Hinshelwood kinetics. The toxicity of the treated samples was evaluated using a Daphnia magna bioassay and was finally decreased by both processes. The results indicated that solar Fenton is more effective than the solar TiO2 process, yielding complete degradation of the examined substrate within 30 min of illumination and dissolved organic carbon (DOC) reduction of about 44% whereas the respective values for the TiO2 process were ?70% degradation of TMP within 120 min of treatment and 13% DOC removal. PMID:23508150

Michael, I; Hapeshi, E; Michael, C; Fatta-Kassinos, D

2013-01-01

332

TiO2 Nanoparticles Produced by Electric-Discharge-Nanofluid-Process as Photoelectrode of DSSC  

Microsoft Academic Search

Self-made TiO2 nanoparticles were used as photoelectrode material of dye sensitized solar cell. The TiO2 thin film coats through spreading nanoparticles evenly onto the ITO glass via self-made spin-heat platform, and then TiO2 thin film is soaked in the dye N-719 more than 12 h to prepare the photoelectrode device. The TiO2 nanoparticles produced by electric-discharge-nanofluid-process have premium anatase crystal

Sih-li Chen; Hung-ting Su; Ho Chang; Ching-song Jwo; Hsiao Ju Feng

2010-01-01

333

Whole Genome Expression Analysis Reveals Differential Effects of TiO2 Nanotubes on Vascular Cells  

PubMed Central

The response of primary human endothelial (ECs) and vascular smooth muscle cells (VSMCs) to TiO2 nanotube arrays is studied through gene expression analysis. Microarrays revealed that nanotubes enhanced EC proliferation and motility, decreased VSMC proliferation, and decreased expression of molecules involved in inflammation and coagulation in both cell types. Networks generated from significantly affected genes suggest that cells may be sensing nanotopographical cues via pathways previously implicated in sensing shear stress.

Peng, Lily; Barczak, Andrea J.; Barbeau, Rebecca A.; Xiao, Yuanyuan; LaTempa, Thomas J.; Grimes, Craig A.; Desai, Tejal A.

2010-01-01

334

Treatment of highly polluted paper mill waste water by solar photocatalytic oxidation with synthesized nano Tio2  

Microsoft Academic Search

Photo catalytic processes in the presence of titanium dioxide provide an interesting route to destroy hazardous organic contaminants, being operational in the UV-A domain with a potential use of solar radiation. The solar photo catalytic degradation of paper mill wastewater has been studied over synthesized nano TIO2. The catalyst was characterized by techniques like x-ray diffraction (XRD)? The enhanced photo

J. Manassah

2011-01-01

335

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

336

TiO2 nanoparticles suppress Escherichia coli cell division in the absence of UV irradiation in acidic conditions.  

PubMed

TiO(2) nanoparticles (NPs) activated by UV irradiation are known to have a bactericidal effect. In this study we report the details of TiO(2) NPs influence on the colony-forming capacity of E. coli in the dark at pH 4.0-4.5. At this pH the bacterial cells are negatively charged and TiO(2) NPs present a positive charge. A 60 min contact between E. coli with TiO(2) at concentrations of 0.02-0.2 mg/mL led to a reduction of E. coli cell number from 10(8) to 10(4)CFU/mL. After the reduction the system remains unchanged during the subsequent incubation. The observed reduction was a function on the initial E. coli concentration. In the presence of 0.04 mg/mL TiO(2) the colony-forming units (CFU) reduction after 60 min was of four-five orders of magnitude when the initial concentration was 10(8) cells/mL. But when starting with an E. coli concentration of 10(7) cells/mL the cell number reduction was less than one order of magnitude. Less than one order of magnitude cell number reduction was also observed for suspensions of E. coli 10(8) cells/mL and 0.002 mg/mL of TiO(2). The bacteria number reduction was always accompanied by the formation of cell aggregates. During cell incubation with TiO(2), the pH of the suspension increased, but did not reach the TiO(2) isoelectric point (IEP). E. coli cells stained with the fluorescent dye acridine orange (AO) showed that the fluorescence of single cells remained unchanged after incubation in the presence of TiO(2). The color change of fluorescence was revealed only in aggregated cells. This suggests changes in the physiologic state of E. coli incorporated into the aggregates. Aggregates of E. coli occur due to the electrostatic interaction between TiO(2) NPs and the bacterial cell surface. A hypothesis is suggested in this study to explain the CFU reduction and the retention of a certain irreducible number of cells capable of further division in the suspension in the presence of TiO(2) in the dark. PMID:22595541

Zhukova, Lyudmila V; Kiwi, John; Nikandrov, Vitaly V

2012-09-01

337

Influence of anatase and rutile phase in TiO2 upon the photocatalytic degradation of methylene blue under solar irradiation in presence of activated carbon.  

PubMed

The influence of activated carbon (AC) on the photocatalytic activity of different crystalline TiO2 phases was verified in the photocatalytic degradation of methylene blue under UV and solar irradiation. The results showed a volcano trend with a maximum photoactivity for the crystalline phase ratio of anatase:rutile equal to 80:20 both under UV or solar irradiation. By contrast, in presence of AC the photocatalytic activity of the binary materials of TiO2/AC followed an exponential trend, increasing as a function of the increase in anatase proportion in the TiO2 framework. The increase in the photoactivity of the binary material TiO2/AC relative to neat TiO2 was up to 22 and about 17 times higher under UV and visible irradiation, respectively. The present results suggest that AC interacts more efficiently with anatase phase than with rutile phase. PMID:24901611

Matos, J; Montaña, R; Rivero, E; Escudero, A; Uzcategui, D

2014-01-01

338

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

339

Fabrication characterization and activity of a solar light driven photocatalyst: cerium doped TiO2 magnetic nanofibers.  

PubMed

A novel magnetic separable composite photocatalytic nanofiber consisting of TiO2 as the major phase, CeO(2-y) and CoFe2O4 as the dopant phase was prepared by sol-gel method and electrospinning technique, and characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), UV-vis diffuse reflectance spectrum (UV-vis DRS) and vibrating sample magnetometer (VSM). The photocatalytic activity of the resultant CoFe2O4-TiO2 and CeO(2-y)/CoFe2O4-TiO2 nanofibers was evaluated by photodegradation of methylene blue (MB) in an aqueous solution under xenon lamp (the irradiation spectrum energy distribution is similar to sunlight) irradiation in a photochemical reactor. The results showed that the dopant of Ce could affect the absorbance ability and photo-response range. The sample containing 1.0 wt% CeO(2-y) exhibited the highest degradation with 35% for MB under simulate solar light irradiation. Furthermore, the as-synthesized composite photocatalytic nanofibers could be separated easily by an external magnetic field, thus it might hold potential for application in wastewater treatment. PMID:22755084

Li, Cong-Ju; Wang, Bin; Wang, Jiao-Na

2012-03-01

340

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

PubMed

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

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

2008-03-01

341

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

342

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

PubMed Central

A simple scalable method to fabricate luminescent monodisperse 200 nm europium doped hollow TiO2 nanoshell particles is reported. Fluorophore reporter, Eu3+ ions, are incorporated directly in the NS matrix, leaving the surface free for functionalization and the core free for payload encapsulation. Amine functionalized polystyrene beads were used as templates, and the porous walls of europium doped titania nanoshells were synthesized using titanium(IV) t-butoxide and europium(III) nitrate as reactants. X-ray diffraction analysis identified anatase as the predominant titania phase of the rigid nanoshell wall structure, and photoluminescence spectra showed that the Eu(III) doped TiO2 nanoshells exhibited a red emission at 617 nm due to an atomic f-f transition. Nanoshell interactions with HeLa cervical cancer cells in vitro were visualized using two-photon microscopy of the Eu(III) emission, and studied using a luminescence ratio analysis to assess nanoshell adhesion and endocytosis.

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

2012-01-01

343

Electrical Conductivity Characteristic of TiO2 Nanowires From Hydrothermal Method  

NASA Astrophysics Data System (ADS)

One dimensional nanostructures of titanium dioxide (TiO2) were synthesized via hydrothermal method by mixing TiO2 as precursor in aqueous solution of NaOH as solvent. Then, heat and washing treatment was applied. Thus obtained wires had diameter ~15nm. TiO2 nanowires will be used as a network in solar cell such dye-sensitized solar cell in order to improve the performance of electron movement in the device. To improve the performance of electron movement, the characteristics of TiO2 nanowires have been analyses using field emission scanning electron microscopy (FESEM) analysis, x-ray diffractometer (XRD) analysis and brunauer emmett teller (BET) analysis. Finally, electrical conductivity of TiO2 nanowires was determined by measuring the resistance of the TiO2 nanowires paste on microscope glass.

Azlishah Othman, Mohd; Faridah Amat, Noor; Hisham Ahmad, Badrul; Rajan, Jose

2014-04-01

344

Enhanced Carrier Transport of N-Doped TiO2 for Photoelectrochemical Cells  

Microsoft Academic Search

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

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

2009-01-01

345

A mixture of anatase and rutile TiO2 nanoparticles induces histamine secretion in mast cells  

PubMed Central

Background Histamine released from mast cells, through complex interactions involving the binding of IgE to Fc?RI receptors and the subsequent intracellular Ca2+ signaling, can mediate many allergic/inflammatory responses. The possibility of titanium dioxide nanoparticles (TiO2 NPs), a nanomaterial pervasively used in nanotechnology and pharmaceutical industries, to directly induce histamine secretion without prior allergen sensitization has remained uncertain. Results TiO2 NP exposure increased both histamine secretion and cytosolic Ca2+ concentration ([Ca2+]C) in a dose dependent manner in rat RBL-2H3 mast cells. The increase in intracellular Ca2+ levels resulted primarily from an extracellular Ca2+ influx via membrane L-type Ca2+ channels. Unspecific Ca2+ entry via TiO2 NP-instigated membrane disruption was demonstrated with the intracellular leakage of a fluorescent calcein dye. Oxidative stress induced by TiO2 NPs also contributed to cytosolic Ca2+ signaling. The PLC-IP3-IP3 receptor pathways and endoplasmic reticulum (ER) were responsible for the sustained elevation of [Ca2+]C and histamine secretion. Conclusion Our data suggests that systemic circulation of NPs may prompt histamine release at different locales causing abnormal inflammatory diseases. This study provides a novel mechanistic link between environmental TiO2 NP exposure and allergen-independent histamine release that can exacerbate manifestations of multiple allergic responses.

2012-01-01

346

Improvement of electron transport in DSSCs by using Nb-doped TiO2 electrodes  

Microsoft Academic Search

The performance of dye-sensitized solar cells (DSSCs) is closely related to efficiency of the electron transport within TiO2-dye-electrolyte system. Electron transport can be improved by modification of the electronic structure of TiO2 electrode by doping with niobium (Nb+5). For this purpose, the DSSCs based on undoped and Nb-doped TiO2 layers were fabricated and their PV parameters and electrical properties were

Tsvetkov Nikolay; Liudmila Larina; Oleg Shevaleevskiy; Byung Tae Ahn

2011-01-01

347

Some studies on TiO2 films deposited by sol-gel technique  

Microsoft Academic Search

TiO2 films are extensively used in various applications including optical multi-layers, sensors, photo catalysis, environmental purification, and solar cells etc. These are prepared by both vacuum and non-vacuum methods. In this paper, we present the results on TiO2 thin films prepared by a sol-gel spin coating process in non-aqueous solvent. Titanium isopropoxide is used as TiO2 precursor. The films were

K. Narasimha Rao; M. Vishwas; Sudhir Kumar Sharma; K. V. Arjuna Gowda

2008-01-01

348

Nanopatterning of spin-coatable TiO2 resist using an electron beam  

Microsoft Academic Search

Titanium dioxide has shown its potential application in solar cells, optical waveguides, gas sensors and photochromic devices. One of the hindrances for miniaturization of these devices is the lack of an easy and reliable way of patterning TiO2. In this paper, we describe a simple process of electron beam patterning of TiO2 using a spin-coatable TiO2 resist prepared by reacting

Mohammad S. Saifullah; Mark E. Welland

2003-01-01

349

Photocatalytic performance of nitrogen, osmium co-doped TiO2 for removal of eosin yellow in water under simulated solar radiation.  

PubMed

Nitrogen, osmium co-doped TiO2 photocatalysts were prepared by a modified sol-gel method using ammonia as the nitrogen source and osmium tetroxide as the source of osmium. The role of rutile phase OsO2 in enhancing the photocatalytic activity of rutile TiO2 towards the degradation of Eosin Yellow was investigated. The materials were characterised by various techniques that include FTIR, Raman, XRD, SEM, EDS, TEM, TGA and DRUV-Vis. The amorphous, oven dried sample was transformed to the anatase and then the rutile phase with increasing calcination temperature. DRUV-Vis analysis revealed a red shift in absorption with increasing calcination temperature, confirmed by a decrease in the band gap of the material. The photocatalytic activity of N, Os co-doped TiO2 was evaluated using eosin yellow degradation and activity increased with increase in calcination temperature under simulated solar irradiation. The rutile phase of the co-doped TiO2 was found to be more effective in degrading the dye (k(a) = 1.84 x 10(-2) min(-1)) compared to the anatase co-doped phase (k(a) = 9.90 x 10(-3) min(-1)). The enhanced photocatalytic activity was ascribed to the synergistic effects of rutile TiO2 and rutile OsO2 in the N, Os co-doped TiO2. PMID:23901525

Kuvarega, Alex T; Krause, Rui W M; Mamba, Bhekie B

2013-07-01

350

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

351

Dye sensitized solar cells.  

PubMed

Dye sensitized solar cell (DSSC) is the only solar cell that can offer both the flexibility and transparency. Its efficiency is comparable to amorphous silicon solar cells but with a much lower cost. This review not only covers the fundamentals of DSSC but also the related cutting-edge research and its development for industrial applications. Most recent research topics on DSSC, for example, applications of nanostructured TiO(2), ZnO electrodes, ionic liquid electrolytes, carbon nanotubes, graphene and solid state DSSC have all been included and discussed. PMID:20480003

Wei, Di

2010-01-01

352

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

353

Surface Treatment for Effective Dye Adsorption on Nanocrystalline TiO2  

NASA Astrophysics Data System (ADS)

To improve the efficiency of dye-sensitized solar cells (DSCs) by controlling dye adsorption on TiO2 surface, the effect of surface treatments on the properties of [NBu4]2[Ru(Htcterpy)(NCS)3] (black dye; [NBu4]: tetrabutylammonium cation; H3tcterpy: 4,4',4''-tricarboxy-2,2':6',2''-terpyridine) on nanocrystalline TiO2 films was investigated by analysis of the photovoltaic performance and the electron transport properties. Although the surface treatments do not affect on the condition band edge of TiO2, the amount of dye on TiO2 increases. The enhancement of dye adsorption by treatment of TiO2 in HCl solution is more effective than that by dipping the dye solution containing deoxycholic acid (DCA) as additive. But the charge recombination between an electron in TiO2 and I3- in the electrolyte can be reduced by the DCA treatment.

Yanagida, Masatoshi; Han, Chen; Han, Liyuan

2012-10-01

354

Removal of Cu(II)-EDTA complex using TiO2/solar light: the effect of operational parameters and feasibility of solar light application.  

PubMed

The photocatalytic oxidation (PCO) of Cu(II)-ethylene diamine tetra acetic acid (EDTA) was investigated at 38 degrees latitude, using natural sunlight instead of artificial UV light. In order to investigate the optimum conditions for the PCO of Cu(II)-EDTA, the effects of several parameters, such as the type and angle of solar collector, solar light intensity, area of the solar reactor and flow rate, on the removals of Cu(II) and dissolved organic carbon (DOC) were examined with 20 L of 10(-4) M Cu(II)-EDTA at pH 4 in a circulating reactor. The removals (%) of Cu(II) and DOC were favorable with the use of a hemispherical collector, with a 38 degrees tilt angle when flat, on a sunny day, and a solar collector with a high area, in a TiO(2) slurry system. On the basis of these experimental results, PCO with solar light irradiation could be used as a feasible technique in the treatment of Cu(II)-EDTA. In addition, PCO with solar light irradiation is regarded as a potential technique in the treatment of real electroplating wastewater when considering the quite similar removal efficiency of Cu(II)-EDTA, with the subsequent removal of the liberated Cu(2+) by adsorption onto the TiO(2) compared to that of synthetic wastewater. PMID:16760083

Cho, Il-Hyoung; Shin, In-Soo; Yang, Jae-Kyu; Lee, Seung-Mok; Shin, Won-Tae

2006-01-01

355

ELECTRONIC PROPERTIES OF TIO 2 DERIVED NANOBELTS  

Microsoft Academic Search

TiO2-based nanostructures are considered good candidates for a number of applications in numerous fields as environmental decontamination, photocatalysis, electrocatalytic storage, solar cells, antibacterial agent, etc (1-3). These applications are based on their electronic properties and high surface area which need to be characterized. Titania derived nanobelts are sensitive to electron beam irradiation requiring to assess the conditions under which the

D. Cadavid; R. F. Egerton; M. Malac; M. S. Moreno

2009-01-01

356

Functionalization of self-organized TiO2 nanotubes with Pd nanoparticles for photocatalytic decomposition of dyes under solar light illumination.  

PubMed

Self-organized, vertically oriented TiO2 nanotube arrays prepared by the sonoelectrochemical anodization method are functionalized with palladium (Pd) nanoparticles of approximately 10 nm size. A simple incipient wetness method is adopted to distribute the Pd nanoparticles uniformly throughout the TiO2 nanotubular surface. This functionalized material is found to be an excellent heterogeneous photocatalyst that can decompose nonbiodegradable azo dyes (e.g., methyl red and methyl orange) rapidly (150-270 min) and efficiently (100%) under ambient conditions using simulated solar light in the absence of any external oxidative radicals such as hydrogen peroxide. PMID:18729485

Mohapatra, Susanta K; Kondamudi, Narasimharao; Banerjee, Subarna; Misra, Mano

2008-10-01

357

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

PubMed Central

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

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

2014-01-01

358

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

359

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

360

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

361

Role of the conducting layer substrate on TiO2 nucleation when using microwave activated chemical bath deposition  

Microsoft Academic Search

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

I. Zumeta; R. Espinosa; J. A. Ayllón; E. Vigil

2002-01-01

362

Synthesis and comprehensive characterizations of new cis-RuL(2)X(2) (X = Cl, CN, and NCS) sensitizers for nanocrystalline TiO(2) solar cell using Bis-phosphonated bipyridine ligands (L).  

PubMed

The preparation and the properties of several ruthenium complexes of the general formula cis-RuL(2)X(2) with L = 2,2'-bipyridine-4,4'-bisphosphonic acid, L' = 2,2'-bipyridine-5,5'-bisphosphonic acid, and X = Cl, CN, or NCS are reported. The synthesis of these complexes relies on the preparation of the key intermediates cis-Ru(bipyridinebis(diethyl ester phosphonate))Cl(2). The ground-state second pK(a) values of the thiocyanato complexes were determined and are 6.0 and 6.1 for cis-RuL(2)(NCS)(2) and for cis-RuL'(2)(NCS)(2), respectively. For these species, (13)C NMR and IR demonstrate that the thiocyanato ligands are bound to Ru via the N atom. The new complexes exhibit a blue-shifted electronic absorption spectrum with respect to the analogous complexes containing carboxylic acid groups. Density functional theory molecular orbital calculations show that the LUMO of the bipyridine phosphonated ligands is at higher energy than the corresponding dicarboxylate complexes and that the thiocyanato ligands are not simple spectator ligands, whose role is to enrich electron density on the ruthenium, but are also involved in transitions from PiRu-NCS to Pibpy that extend the absorbance of the dye in the low energy part of the absorption spectrum. The photoaction spectra recorded in a sandwich regenerative photovoltaic cell indicate that the cyano and thiocyanato complexes containing the bipyridine substituted in 4,4' positions exhibit a 90-95% photoconversion efficiency on the MLCT band, whereas those containing the bipyridine substituted in 5,5' positions display lower efficiency (60-65%). The most efficient complex in the series is cis-RuL(2)(NCS)(2); however, its overall efficiency is about 30% lower than the analogue cis-Ru(H(2)dcb)(2)(NCS)(2) (H(2)dcb = 2,2'-bipyridine-4,4'-dicarboxylic acid) due to a lower absorbance in the red part of the visible spectrum. PMID:14552617

Zabri, Hervé; Gillaizeau, Isabelle; Bignozzi, Carlo Alberto; Caramori, Stefano; Charlot, Marie-France; Cano-Boquera, Joan; Odobel, Fabrice

2003-10-20

363

Solid-state dye PV cells using inverse opal TiO 2 films  

Microsoft Academic Search

A novel approach to increase the efficiency of solid-state Gratzel solar cells is presented. Large surface, titania inverse opal films is prepared, and used in fabricating solid-state dye sensitised organic–inorganic hybrid Gratzel solar cells. The ordered interconnected cavities forming the microporous structure allow an easy and desired penetration of both the dye and the solid-state hole conductor material favouring the

P. R. Somani; C. Dionigi; M. Murgia; D. Palles; P. Nozar; G. Ruani

2005-01-01

364

Solar Fenton and solar TiO2 catalytic treatment of ofloxacin in secondary treated effluents: evaluation of operational and kinetic parameters.  

PubMed

Two different technical approaches based on advanced oxidation processes (AOPs), solar Fenton homogeneous photocatalysis (hv/Fe(2+)/H(2)O(2)) and heterogeneous photocatalysis with titanium dioxide (TiO(2)) suspensions were studied for the chemical degradation of the fluoroquinolone ofloxacin in secondary treated effluents. A bench-scale solar simulator in combination with an appropriate photochemical batch reactor was used to evaluate and select the optimal oxidation conditions of ofloxacin spiked in secondary treated domestic effluents. The concentration profile of the examined substrate during degradation was determined by UV/Vis spectrophotometry. Mineralization was monitored by measuring the dissolved organic carbon (DOC). The concentrations of Fe(2+) and H(2)O(2) were the key factors for the solar Fenton process, while the most important parameter of the heterogeneous photocatalysis was proved to be the catalyst loading. Kinetic analyses indicated that the photodegradation of ofloxacin can be described by a pseudo-first-order reaction. The rate constant (k) for the solar Fenton process was determined at different Fe(2+) and H(2)O(2) concentrations whereas the Langmuir-Hinshelwood (LH) kinetic expression was used to assess the kinetics of the heterogeneous photocatalytic process. The conversion of ofloxacin depends on several parameters based on the various experimental conditions, which were investigated. A Daphnia magna bioassay was used to evaluate the potential toxicity of the parent compound and its photo-oxidation by-products in different stages of oxidation. In the present study solar Fenton has been demonstrated to be more effective than the solar TiO(2) process, yielding complete degradation of the examined substrate and DOC reduction of about 50% in 30 min of the photocatalytic treatment. PMID:20667580

Michael, I; Hapeshi, E; Michael, C; Fatta-Kassinos, D

2010-10-01

365

Boosting fuel cell performance with a semiconductor photocatalyst: TiO2/Pt-Ru hybrid catalyst for methanol oxidation.  

PubMed

A hybrid carbon fiber electrode (CFE) consisting of TiO2 semiconductor photocatalyst and Pt-Ru catalyst has been developed to boost the performance of direct methanol fuel cells (DMFC). These two catalyst nanoparticles are deposited on opposite sides of the carbon fiber paper such that methanol oxidation is carried out catalytically on Pt-Ru and photocatalytically on TiO2 under UV-light irradiation. Since both catalysts carry out methanol oxidation independently, we observe an additive effect in the current generation. The carbon support fibers provide a large network to collect the electrons from both of these catalytic processes and thus assist in efficient current generation. In addition, TiO2 improves the performance of the Pt-Ru catalyst in dark, indicating possible surface area improvement or diminished poisoning effects. The concept of incorporating a photocatalyst provides new ways to minimize precious metal content and enhance the performance of DMFCs. At low catalyst loadings (0.15 mg/cm2) at 295 K, a 25% enhancement in the peak power density is observed upon illumination with light. PMID:16852456

Drew, Kristine; Girishkumar, G; Vinodgopal, K; Kamat, Prashant V

2005-06-23

366

Degradation of Reactive Black 5 using combined electrochemical degradation-solar-light/immobilized TiO2 film process and toxicity evaluation.  

PubMed

The combined electrochemical oxidation-solar-light/immobilized TiO2 film process was conducted to degrade an azo dye, Reactive Black 5 (RB5). The toxicity was also monitored by the Vibrio fischeri light inhibition test. The electrochemical oxidation rapidly decolorized RB5 (55, 110 microM) with a supporting electrolyte of 2 gl(-1) NaCl at current density 277Am(-2) and pH 4. However, TOC mineralization and A(310) removal were low. Additionally, the treated solution showed high biotoxicity. RB5 at 110 microM significantly retarded the de-colorization efficiency by using the solar-light/immobilized TiO2 film process. The combined electrochemical oxidation-solar-light/immobilized TiO2 process effectively increased the removal of color, A(310), and TOC. The toxicity was also significantly reduced after 3h of solar irradiation. The results indicated that the low-cost combined process is a potential technique for rapid treatment of RB5. PMID:18359062

Wang, Kai-Sung; Chen, Hsueh-Yu; Huang, Long-Chiu; Su, Yu-Chun; Chang, Shih-Hsien

2008-05-01

367

Hierarchically multifunctional K-OMS-2/TiO2/Fe3O4 heterojunctions for the photocatalytic oxidation of humic acid under solar light irradiation.  

PubMed

A multifunctional heterojunctioned K-OMS-2/TiO(2)/Fe(3)O(4) (KTF) nanocomposite was successfully synthesized using a combination of hydrothermal and co-precipitation techniques. The resultant sample was characterized by XRD, FESEM, TEM, N(2) adsorption, XPS and VSM. Its photocatalytic activity was demonstrated in the photocatalytic degradation of humic acid (HA). Morphology characterization showed the hierarchical structure of the synthesized material, and XRD results revealed that both the rutile and anatase TiO(2) structures are present in the sample. The average pore diameters and BET surface area of the synthesized KTF heterojunctions were 40 nm and 134.42 m(2)/g, respectively. XPS spectra confirmed the presence of Fe(3)O(4) and TiO(2) in the synthesized material, and the valences of Mn were kept at +3 and +4 after the grafting of Fe(3)O(4) and TiO(2). The synthesized material showed good magnetic response and photocatalytic activity under simulated solar light irradiation, and 85.7% of HA was decomposed after 120 min in the presence of KTF nanocomposites. The reusability study suggested that the magnetic recovered material was stable enough for multiple recycling usages, verifying its potential application in water purification. PMID:23140876

Zhang, Tong; Yan, Xiaoli; Sun, Darren Delai

2012-12-01

368

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

369

The design, fabrication, and photocatalytic utility of nanostructured semiconductors: focus on TiO2-based nanostructures  

PubMed Central

Recent advances in basic fabrication techniques of TiO2-based nanomaterials such as nanoparticles, nanowires, nanoplatelets, and both physical- and solution-based techniques have been adopted by various research groups around the world. Our research focus has been mainly on various deposition parameters used for fabricating nanostructured materials, including TiO2-organic/inorganic nanocomposite materials. Technically, TiO2 shows relatively high reactivity under ultraviolet light, the energy of which exceeds the band gap of TiO2. The development of photocatalysts exhibiting high reactivity under visible light allows the main part of the solar spectrum to be used. Visible light-activated TiO2 could be prepared by doping or sensitizing. As far as doping of TiO2 is concerned, in obtaining tailored material with improved properties, metal and nonmetal doping has been performed in the context of improved photoactivity. Nonmetal doping seems to be more promising than metal doping. TiO2 represents an effective photocatalyst for water and air purification and for self-cleaning surfaces. Additionally, it can be used as an antibacterial agent because of its strong oxidation activity and superhydrophilicity. Therefore, applications of TiO2 in terms of photocatalytic activities are discussed here. The basic mechanisms of the photoactivities of TiO2 and nanostructures are considered alongside band structure engineering and surface modification in nanostructured TiO2 in the context of doping. The article reviews the basic structural, optical, and electrical properties of TiO2, followed by detailed fabrication techniques of 0-, 1-, and quasi-2-dimensional TiO2 nanomaterials. Applications and future directions of nanostructured TiO2 are considered in the context of various photoinduced phenomena such as hydrogen production, electricity generation via dye-sensitized solar cells, photokilling and self-cleaning effect, photo-oxidation of organic pollutant, wastewater management, and organic synthesis.

Banerjee, Arghya Narayan

2011-01-01

370

Dye-sensitized solar cells, from cell to module  

Microsoft Academic Search

This paper shows the detailed results of different particle-based and nanocrystalline TiO2 films prepared by sol–gel technology using precursors with different pH and autoclaving at different temperatures to produce dye-sensitized solar cells (DSCs). The thickness of the TiO2 film in the DSC was optimized as well. The designs of DSC modules, using series and parallel connections, will be shown in

Songyuan Dai; Jian Weng; Yifeng Sui; Chengwu Shi; Yang Huang; Shuanhong Chen; Xu Pan; Xiaqin Fang; Linhua Hu; Fantai Kong; Kongjia Wang

2004-01-01

371

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

372

Biocompatible TiO2 nanoparticle-based cell immunoassay for circulating tumor cells capture and identification from cancer patients.  

PubMed

We demonstrate the isolation of circulating tumor cells (CTCs) with a biocompatible nano-film composed of TiO2 nanoparticles. Due to the enhanced topographic interaction between nano-film and cancer cell surface, cancer cells (HCT116) spiked into PBS and healthy blood can be recovered from the suspension, whose efficiencies were respectively 80 % and 50 %. Benifit from the biocompatibility of this nano-film, in-situ culture of the captured cancer cells is also available, which provides an alternative selection when the capture cell number was inadequate or the sample cannot be analyzed immediately. For the proof-of-concept study, we use this nano-film to separate the circulating tumor cells from the colorectal and gastric cancer patient peripheral blood samples and the captured CTCs are identified by a three-colored immunocytochemistry method. We investigated the cancer cells capture strength at the nano-bio interface through exposing the cells to fluid shear stress in microfluidic device, which can be utilized to increase the purity of CTCs. The result indicated that 50 % of the captured cells can be detached from the substrate when the fluid shear stress was 180 dyn cm(-2). By integration of this CTCs capture nano-film with other single cell analysis device, we expected to further explore their applications in genome sequencing based on the captured CTCs. PMID:23780622

He, Rongxiang; Zhao, Libo; Liu, Yumin; Zhang, Nangang; Cheng, Boran; He, Zhaobo; Cai, Bo; Li, Sizhe; Liu, Wei; Guo, Shishang; Chen, Yong; Xiong, Bin; Zhao, Xing-Zhong

2013-08-01

373

Effects of subtoxic concentrations of TiO2 and ZnO nanoparticles on human lymphocytes, dendritic cells and exosome production.  

PubMed

Metal oxide nanoparticles are widely used in the paint and coating industry as well as in cosmetics, but the knowledge of their possible interactions with the immune system is very limited. Our aims were to investigate if commercially available TiO(2) and ZnO nanoparticles may affect different human immune cells and their production of exosomes, nano-sized vesicles that have a role in cell to cell communication. We found that the TiO(2) or ZnO nanoparticles at concentrations from 1 to 100?g/mL did not affect the viability of primary human peripheral blood mononuclear cells (PBMC). In contrast, monocyte-derived dendritic cells (MDDC) reacted with a dose dependent increase in cell death and caspase activity to ZnO but not to TiO(2) nanoparticles. Non-toxic exposure, 10?g/mL, to TiO(2) and ZnO nanoparticles did not significantly alter the phenotype of MDDC. Interestingly, ZnO but not TiO(2) nanoparticles induced a down regulation of Fc?RIII (CD16) expression on NK-cells in the PBMC population, suggesting that subtoxic concentrations of ZnO nanoparticles might have an effect on Fc?R-mediated immune responses. The phenotype and size of exosomes produced by PBMC or MDDC exposed to the nanoparticles were similar to that of exosomes harvested from control cultures. TiO(2) or ZnO nanoparticles could not be detected within or associated to exosomes as analyzed with TEM. We conclude that TiO(2) and ZnO nanoparticles differently affect immune cells and that evaluations of nanoparticles should be performed even at subtoxic concentrations on different primary human immune cells when investigating potential effects on immune functions. PMID:22842014

Andersson-Willman, Britta; Gehrmann, Ulf; Cansu, Zekiye; Buerki-Thurnherr, Tina; Krug, Harald F; Gabrielsson, Susanne; Scheynius, Annika

2012-10-01

374

An approach to laminated flexible Dye sensitized solar cells  

Microsoft Academic Search

We have built TiO2 Dye sensitized solar cells (DSSCs) that combined flexible TiO2 photoanodes coated on ITO\\/PET substrates with a gel electrolyte based on PVDF–HFP–SiO2 films. Titanium isopropoxide (TiP4) was used as additive to TiO2 nanoparticles for increasing power conversion efficiency in Dye sensitized solar cell electrodes prepared at low-temperature (130°C). An efficiency ?AM1.5G=3.55% on ITO\\/PET substrates is obtained at

Aurelien Du Pasquier

2007-01-01

375

Enhanced DSSC performance with high surface area thin anatase TiO 2 nanoleaves  

Microsoft Academic Search

Thin anatase TiO2 nanoleaves (NLs) with high surface area (?93m2\\/g) are synthesized by hydrothermal route and dye-sensitized solar cells (DSSC) made using such NLs are compared with those made with hydro-thermally synthesized TiO2 nanoparticles and the Degussa P25 powder. The NLs-based DSSCs show increment of 16% and 24% in the total conversion efficiency over the cells made with NPs and

Vivek Dhas; Subas Muduli; Shruti Agarkar; Abhimanyu Rana; Beatrice Hannoyer; Rahul Banerjee; Satishchandra Ogale

2011-01-01

376

Electrospinning processed nanofibrous TiO(2) membranes for photovoltaic applications.  

PubMed

We have recently fabricated dye-sensitized solar cells (DSSCs) comprising nanofibrous TiO(2) membranes as electrode materials. A thin TiO(2) film was pre-deposited on fluorine doped tin oxide (FTO) coated conducting glass substrate by immersion in TiF(4) aqueous solution to reduce the electron back-transfer from FTO to the electrolyte. The composite polyvinyl acetate (PVac)/titania nanofibrous membranes can be deposited on the pre-deposited thin TiO(2) film coated FTO by electrospinning of a mixture of PVac and titanium isopropoxide in N,N-dimethylformamide (DMF). The nanofibrous TiO(2) membranes were obtained by calcining the electrospun composite nanofibres of PVac/titania as the precursor. Spectral sensitization of the nanofibrous TiO(2) membranes was carried out with a ruthenium (II) complex, cis-dithiocyanate-N,N(')-bis(2,2(')-bipyridyl-4,4(')-dicarboxylic acid) ruthenium (II) dihydrate. The results indicated that the photocurrent and conversion efficiency of electrodes can be increased with the addition of the pre-deposited TiO(2) film and the adhesion treatment using DMF. Additionally, the dye loading, photocurrent, and efficiency of the electrodes were gradually increased by increasing the average thickness of the nanofibrous TiO(2) membranes. The efficiency of the fibrous TiO(2) photoelectrode with the average membrane thickness of 3.9 µm has a maximum value of 4.14%. PMID:21727376

Onozuka, Katsuhiro; Ding, Bin; Tsuge, Yosuke; Naka, Takayuki; Yamazaki, Michiyo; Sugi, Shinichiro; Ohno, Shingo; Yoshikawa, Masato; Shiratori, Seimei

2006-02-28

377

High-performance method for specific effect on nucleic acids in cells using TiO2~DNA nanocomposites  

NASA Astrophysics Data System (ADS)

Nanoparticles are used to solve the current drug delivery problem. We present a high-performance method for efficient and selective action on nucleic acid target in cells using unique TiO2.PL-DNA nanocomposites (polylysine-containing DNA fragments noncovalently immobilized onto TiO2 nanoparticles capable of transferring DNA). These nanocomposites were used for inhibition of human influenza A (H3N2) virus replication in infected MDCK cells. They showed a low toxicity (TC50 ~ 1800 ?g/ml) and a high antiviral activity (>99.9% inhibition of the virus replication). The specificity factor (antisense effect) appeared to depend on the delivery system of DNA fragments. This factor for nanocomposites is ten-times higher than for DNA in the presence of lipofectamine. IC50 for nanocomposites was estimated to be 1.5 ?g/ml (30 nM for DNA), so its selectivity index was calculated as ~1200. Thus, the proposed nanocomposites are prospective for therapeutic application.

Levina, Asya S.; Repkova, Marina N.; Ismagilov, Zinfer R.; Shikina, Nadezhda V.; Malygin, Ernst G.; Mazurkova, Natalia A.; Zinov'ev, Victor V.; Evdokimov, Alexei A.; Baiborodin, Sergei I.; Zarytova, Valentina F.

2012-10-01

378

Nb doped TiO2 as a Cathode Catalyst Support Material for Polymer Electrolyte Membrane Fuel Cells  

NASA Astrophysics Data System (ADS)

In order to reduce the emissions of greenhouse gases and reduce dependence on the use of fossil fuels, it is necessary to pursue alternative sources of energy. Transportation is a major contributor to the emission of greenhouse gases due to the use of fossil fuels in the internal combustion engine. To reduce emission of these pollutants into the atmosphere, research is needed to produce alternative solutions for vehicle transportation. Low temperature polymer electrolyte membrane fuel cells are energy conversion devices that provide an alternative to the internal combustion engine, however, they still have obstacles to overcome to achieve large scale implementation. T he following work presents original research with regards to the development of Nb doped TiO2 as a cathode catalyst support material for low temperature polymer electrolyte membrane fuel cells. The development of a new process to synthesize nanoparticles of Nb doped TiO2 with controlled compositions is presented as well as methods to scale up the process and optimize the synthesis for the aforementioned application. In addition to this, comparison of both electrochemical activity and durability with current state of the art Pt on high surface area carbon black (Vulcan XC-72) is investigated. Effects of the strong metal-support interaction on the electrochemical behavior of these materials is also observed and discussed.

O'Toole, Alexander W.

379

High-performance method for specific effect on nucleic acids in cells using TiO2~DNA nanocomposites.  

PubMed

Nanoparticles are used to solve the current drug delivery problem. We present a high-performance method for efficient and selective action on nucleic acid target in cells using unique TiO(2)·PL-DNA nanocomposites (polylysine-containing DNA fragments noncovalently immobilized onto TiO(2) nanoparticles capable of transferring DNA). These nanocomposites were used for inhibition of human influenza A (H3N2) virus replication in infected MDCK cells. They showed a low toxicity (TC(50) ? 1800 ?g/ml) and a high antiviral activity (>99.9% inhibition of the virus replication). The specificity factor (antisense effect) appeared to depend on the delivery system of DNA fragments. This factor for nanocomposites is ten-times higher than for DNA in the presence of lipofectamine. IC(50) for nanocomposites was estimated to be 1.5 ?g/ml (30 nM for DNA), so its selectivity index was calculated as ~1200. Thus, the proposed nanocomposites are prospective for therapeutic application. PMID:23091696

Levina, Asya S; Repkova, Marina N; Ismagilov, Zinfer R; Shikina, Nadezhda V; Malygin, Ernst G; Mazurkova, Natalia A; Zinov'ev, Victor V; Evdokimov, Alexei A; Baiborodin, Sergei I; Zarytova, Valentina F

2012-01-01

380

High-performance method for specific effect on nucleic acids in cells using TiO2~DNA nanocomposites  

PubMed Central

Nanoparticles are used to solve the current drug delivery problem. We present a high-performance method for efficient and selective action on nucleic acid target in cells using unique TiO2·PL-DNA nanocomposites (polylysine-containing DNA fragments noncovalently immobilized onto TiO2 nanoparticles capable of transferring DNA). These nanocomposites were used for inhibition of human influenza A (H3N2) virus replication in infected MDCK cells. They showed a low toxicity (TC50 ? 1800 ?g/ml) and a high antiviral activity (>99.9% inhibition of the virus replication). The specificity factor (antisense effect) appeared to depend on the delivery system of DNA fragments. This factor for nanocomposites is ten-times higher than for DNA in the presence of lipofectamine. IC50 for nanocomposites was estimated to be 1.5 ?g/ml (30 nM for DNA), so its selectivity index was calculated as ~1200. Thus, the proposed nanocomposites are prospective for therapeutic application.

Levina, Asya S.; Repkova, Marina N.; Ismagilov, Zinfer R.; Shikina, Nadezhda V.; Malygin, Ernst G.; Mazurkova, Natalia A.; Zinov'ev, Victor V.; Evdokimov, Alexei A.; Baiborodin, Sergei I.; Zarytova, Valentina F.

2012-01-01

381

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 ...

382

Dye-Sensitized Solar Cells with Conversion Efficiency of 11.1%  

Microsoft Academic Search

Dye-sensitized solar cells (DSCs) using titanium dioxide (TiO2) electrodes with different haze were investigated. It was found that the incident photon to current efficiency (\\\\mathit{IPCE}) of DSCs increases with increase in the haze of the TiO2 electrodes, especially in the near infrared wavelength region. Conversion efficiency of 11.1%, measured by a public test center, was achieved using high haze TiO2

Yasuo Chiba; Ashraful Islam; Yuki Watanabe; Ryoichi Komiya; Naoki Koide; Liyuan Han

2006-01-01

383

The performances of the mercurochrome-sensitized composite semiconductor photoelectrochemical cells based on TiO 2\\/SnO 2 and ZnO\\/SnO 2 composites  

Microsoft Academic Search

Mercurochrome-sensitized composite TiO2\\/SnO2 and ZnO\\/SnO2 photoelectrochemical cells (DSC) have been fabricated from the mixture of the SnO2 particles and the semiconductor colloid (TiO2, ZnO). The influence of the mixed ratio on the performances of the composite semiconductor photoelectrochemical cells was studied. Comparing the composite TiO2\\/SnO2 and ZnO\\/SnO2 cells with the corresponding TiO2 and ZnO cells, the incident photon-to-current conversion efficiency

Zhaoyue Liu; Kai Pan; Qinglin Zhang; Min Liu; Ruokun Jia; Qiang Lü; Dejun Wang; Yubai Bai; Tiejin Li

2004-01-01

384

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

385

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

386

TiO2-doped phosphate glass microcarriers: A stable bioactive substrate for expansion of adherent mammalian cells  

PubMed Central

Scalable expansion of cells for regenerative cell therapy or to produce large quantities for high-throughput screening remains a challenge for bioprocess engineers. Laboratory scale cell expansion using t-flasks requires frequent passaging that exposes cells to many poorly defined bioprocess forces that can cause damage or alter their phenotype. Microcarriers offer a potential solution to scalable production, lending themselves to cell culture processes more akin to fermentation, removing the need for frequent passaging throughout the expansion period. One main problem with microcarrier expansion, however, is the difficulty in harvesting cells at the end of the process. Therefore, therapies that rely on cell delivery using biomaterial scaffolds could benefit from a microcarrier expansion system whereby the cells and microcarriers are transplanted together. In the current study, we used bioactive glass microcarriers doped with 5% TiO2 that display a controlled rate of degradation and conducted experiments to assess biocompatibility and growth of primary fibroblast cells as a model for cell therapy products. We found that the microcarriers are highly biocompatible and facilitate cell growth in a gradual controlled manner. Therefore, even without additional biofunctionalization methods, Ti-doped bioactive glass microcarriers offer potential as a cell expansion platform.

Guedes, Joana C; Park, Jeong-Hui; Lakhkar, Nilay J; Kim, Hae-Won; Knowles, Jonathan C

2013-01-01

387

Solar-powered potentially induced TiO 2, ZnO and SnO 2-catalyzed iodine generation  

Microsoft Academic Search

Formation of iodine from air-saturated KI solution under natural sunlight (950±25Wm?2) with nanocrystals of TiO2 in different phase compositions, ZnO and SnO2, characterized by powder XRD, UV-visible diffuse reflectance and impedance spectroscopies, increases by 3–9 fold on impressing a cathodic bias of ?0.2V (vs NHE) to the semiconductors. The iodine generation essentially requires light, the semiconductor and dissolved oxygen. An

C. Karunakaran; P. Anilkumar; G. Manikandan; P. Gomathisankar

2010-01-01

388

Application of the colloidal stability of TiO 2 particles for recovery and reuse in solar photocatalysis  

Microsoft Academic Search

TiO2-catalyst suspensions work efficiently in photocatalysis for wastewater treatment. Nevertheless, once photocatalysis is complete, separation of the catalyst from solution becomes the main problem. Catalyst recovery has been enhanced through charge neutralisation and coagulation with electrolytes at lab and pilot-plant scale (40L) to evaluate the potential for its separation after photocatalytic degradation of pollutants. Zeta-potential analysis showed that the isoelectric

P. Fernández-Ibáñez; J. Blanco; S. Malato; F. J. de las Nieves

2003-01-01

389

High open circuit voltages of solar cells based on quantum dot and dye hybrid-sensitization  

NASA Astrophysics Data System (ADS)

A type of solar cell based on quantum dot (QD) and dye hybrid-sensitized mesoporous TiO2 film electrode was designed and reported. The electrode was consisted of a TiO2 nanoparticle (NP) thin film layer sensitized with CdS quantum dot (QD) and an amorphous TiO2 coated TiO2 NP thin film layer that sensitized with C106 dye. The amorphous TiO2 layer was obtained by TiCl4 post-treatment to improve the properties of solar cells. Research showed that the solar cells fabricated with as-prepared hybrid-sensitized electrode exhibited excellent photovoltaic performances and a fairly high open circuit voltage of 796 mV was achieved.

Zhao, Yujie; Bala, Hari; Zhao, Wanyu; Chen, Jingkuo; Li, Huayang; Fu, Wuyou; Sun, Guang; Cao, Jianliang; Zhang, Zhanying

2014-01-01

390

Electrical switching effect of a single-unit-cell CrO2 layer on rutile TiO2 surface  

NASA Astrophysics Data System (ADS)

Rutile CrO2 is the most important half-metallic material with nearly 100% spin polarization at the Fermi level, and rutile TiO2 is a wide-gap semiconductor with many applications. Here, we show through first-principles investigation that a single-unit-cell CrO2 layer on rutile TiO2 (001) surface is ferromagnetic and semiconductive with a gap of 0.54 eV, and its electronic state transits abruptly to a typical metallic state when an electrical field is applied. Consequently, this makes an interesting electrical switching effect which may be useful in designing spintronic devices.

Li, Si-Da; Liu, Bang-Gui

2014-03-01

391

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

392

Peptide-templating dye-sensitized solar cells.  

PubMed

A hollow TiO(2) nanoribbon network electrode for dye-sensitized solar cells (DSSC) was fabricated by a biotemplating process combining peptide self-assembly and atomic layer deposition (ALD). An aromatic peptide of diphenylalanine was assembled into a three-dimensional network consisting of highly entangled nanoribbons. A thin TiO(2) layer was deposited at the surface of the peptide template via the ALD process. After the pyrolysis of the peptide template, a highly entangled nanotubular TiO(2) framework was successfully prepared. Evolution of the crystal phase and crystallite size of the TiO(2) nanostructure was exploited by controlling the calcination temperature. Finally, the hollow TiO(2) nanoribbon network electrode was integrated into DSSC devices and their photochemical performances were investigated. Hollow TiO(2) nanoribbon-based DSSCs exhibited a power conversion efficiency of 3.8%, which is comparable to the conventional TiO(2) nanoparticle-based DSSCs (3.5%). Our approach offers a novel pathway for DSSCs consisting of TiO(2) electrodes via biotemplating. PMID:20378945

Han, Tae Hee; Moon, Hyoung-Seok; Hwang, Jin Ok; Seok, Sang Il; Im, Sang Hyuk; Kim, Sang Ouk

2010-05-01

393

Variation of cell spreading on TiO2 film modified by 775 nm and 388 nm femtosecond laser irradiation  

NASA Astrophysics Data System (ADS)

Titanium (Ti) is one of the most used biomaterials in metals. However, Ti is typically artificial materials. Thus, it is necessary for improving the biocompatibility of Ti. Recently, coating of the titanium dioxides (TiO2) film on Ti plate has been proposed to improve biocompatibility of Ti. We have developed coating method of the film on Ti plate with an aerosol beam. Periodic structures formation on biomaterials was also a useful method for improving the biocompatibility. Direction of cell spreading might be controlled along the grooves of periodic microstructures. In our previous study, periodic nanostructures were formed on the film by femtosecond laser irradiation at fundamental wave (775 nm). Period of the periodic nanostructures was about 230 nm. In cell test, cell spreading along the grooves of the periodic nanostructures was observed although it was not done for the film without the periodic nanostructures. Then, influence of the period of the periodic nanostructures on cell spreading has not been investigated yet. The period might be changed by changing the laser wavelength. In this study, the periodic nanostructures were created on the film with femtosecond laser at 775nm and 388 nm, respectively. After cell test, cell spreading along the grooves of the periodic nanostructures was observed on 775 nm and 388nm laser irradiated areas. Distribution of direction of cell spreading on laser irradiated area was also examined. These results suggested that controlling the cell spreading on periodic nanostructures with period of 230 nm was better than that with period of 130 nm.

Tsukamoto, M.; Shinonaga, T.; Sato, Y.; Chen, P.; Nagai, A.; Hanawa, T.

2014-03-01

394

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

395

Enhancement of the photoproperties of solid-state TiO2|dye|CuI cells by coupling of two dyes  

NASA Astrophysics Data System (ADS)

The electronic coupling of a natural pigment extracted from pomegranate fruits (rich with cyanin and exist as flavylium at natural PH) with an organic dye mercurochrome enhanced the performance of solid-state TiO2|dye|CuI-type photovoltaic cells sensitized from pomegranate pigments or mercurochrome individually.

Sirimanne, P. M.; Senevirathna, M. K. I.; Premalal, E. V. A.; Pitigala, P. K. D. D. P.

2006-06-01

396

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

397

Degradation of glyphosate in soil photocatalyzed by Fe3O4/SiO2/TiO2 under solar light.  

PubMed

In this study, Fe(3)O(4)/SiO(2)/TiO(2) photocatalyst was prepared via a sol-gel method, and Fe(3)O(4) particles were used as the core of the colloid. Diffraction peaks of Fe(3)O(4) crystals are not found by XRD characterization, indicating that Fe(3)O(4) particles are well encapsulated by SiO(2). FTIR characterization shows that diffraction peaks of Ti-O-Si chemical bonds become obvious when the Fe(3)O(4) loading is more than 0.5%. SEM characterization indicates that agglomeration occurs in the Fe(3)O(4)/SiO(2)/TiO(2) photocatalyst, whereas photocatalysts modified by Fe(3)O(4)/SiO(2) present excellent visible light absorption performance and photocatalytic activity, especially when the Fe(3)O(4) loading is 0.5%. Photocatalytic degradation of glyphosate in soil by these photocatalysts under solar irradiation was investigated. Results show that 0.5% Fe(3)O(4)/SiO(2)/TiO(2) has the best photocatalytic activity. The best moisture content of soil is 30%~50%. Degradation efficiency of glyphosate reaches 89% in 2 h when the dosage of photocatalyst is 0.4 g/100 g (soil), and it increased slowly when more photocatalyst was used. Soil thickness is a very important factor for the photocatalytic rate. The thinner the soil is, the better the glyphosate degradation is. Degradation of glyphosate is not obviously affected by sunlight intensity when the intensity is below 6 mW/cm(2) or above 10 mW/cm(2), but it is accelerated significantly when the sunlight intensity increases from 6 mW/cm(2) to 10 mW/cm(2). PMID:21695039

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

2011-04-01

398

Electrospun anatase-phase TiO2 nanofibers with different morphological structures and specific surface areas.  

PubMed

Electrospun anatase-phase TiO2 nanofibers with desired morphological structure and relatively high specific surface area are expected to outperform other nanostructures (e.g., powder and film) of TiO2 for various applications (particularly dye-sensitized solar cell and photo-catalysis). In this study, systematic investigations were carried out to prepare and characterize electrospun anatase-phase TiO2 nanofibers with different morphological structures (e.g., solid, hollow/tubular, and porous) and specific surface areas. The TiO2 nanofibers were generally prepared via electrospinning of precursor nanofibers followed by pyrolysis at 500°C. For making hollow/tubular TiO2 nanofibers, the technique of co-axial electrospinning was utilized; while for making porous TiO2 nanofibers, the etching treatment in NaOH aqueous solution was adopted. The results indicated that the hollow/tubular TiO2 nanofibers (with diameters of ~300-500 nm and wall-thickness in the range from tens of nanometers to ~200 nm) had the BET specific surface area of ~27.3 m(2)/g, which was approximately twice as that of the solid TiO2 nanofibers (~15.2 m(2)/g) with diameters of ~200-300 nm and lengths of at least tens of microns. Porous TiO2 nanofibers made from the precursor of Al2O3/TiO2 composite nanofibers had the BET specific surface area of ~106.5 m(2)/g, whereas porous TiO2 nanofibers made from the precursor of ZnO/TiO2 composite nanofibers had the highest BET specific surface area of ~148.6 m(2)/g. PMID:23489604

He, Guangfei; Cai, Yibing; Zhao, Yong; Wang, Xiaoxu; Lai, Chuilin; Xi, Min; Zhu, Zhengtao; Fong, Hao

2013-05-15

399

Interfacial Electron Transfer in TiO2 Surfaces Sensitized with Ru(II)-Polypyridine Complexes  

NASA Astrophysics Data System (ADS)

Studies of interfacial electron transfer (IET) in TiO2 surfaces functionalized with (1) pyridine-4-phosphonic acid, (2) [Ru(tpy)(tpy(PO3H2))]2+, and (3) [Ru(tpy)(bpy)(H2O)-Ru(tpy)(tpy(PO3H2))]4+ (tpy = 2,2':6,2''-terpyridine; bpy = 2,2'-bipyridine) are reported. We characterize the electronic excitations, electron injection time scales, and interfacial electron transfer (IET) mechanisms through phosphonate anchoring groups. These are promising alternatives to the classic carboxylates of conventional dye-sensitized solar cells since they bind more strongly to TiO2 surfaces and form stable covalent bonds that are unaffected by humidity. Density functional theory calculations and quantum dynamics simulations of IET indicate that electron injection in 1-TiO2 can be up to 1 order of magnitude faster when 1 is attached to TiO2 in a bidentate mode (? ˜ 60 fs) than when attached in a monodentate motif (? ˜ 460 fs). The IET time scale also depends strongly on the properties of the sensitizer as well as on the nature of the electronic excitation initially localized in the adsorbate molecule. We show that IET triggered by the visible light excitation of 2-TiO2 takes 1-10 ps when 2 is attached in a bidentate mode, a time comparable to the lifetime of the excited electronic state. IET due to visible-light photoexcitation of 3-TiO2 is slower, since the resulting electronic excitation remains localized in the tpy-tpy bridge that is weakly coupled to the electronic states of the conduction band of TiO2. These results are particularly valuable to elucidate the possible origin of IET efficiency drops during photoconversion in solar cells based on Ru(II)-polypyridine complexes covalently attached to TiO2 thin films with phosphonate linkers.

Jakubikova, Elena; Snoeberger, Robert C., III; Batista, Victor S.; Martin, Richard L.; Batista, Enrique R.

2009-07-01

400

Application of a Schottky barrier to dye-sensitized solar cells (DSSCs) with multilayer thin films of photoelectrodes  

Microsoft Academic Search

This study combines Au nanoparticles with TiO2 nanoparticles to form a Schottky barrier, and applies it to the photoelectrode thin film of dye-sensitized solar cells (DSSCs). First, commercial TiO2 powder (Degussa P25) is put in the alkaline solution to prepare for TiO nanotubes (Tnt) by using hydrothermal treatment. Tnt are sintered at 550°C to obtain Tnt-C550 particles. In addition, TiO2

Ho Chang; Kun-Ching Cho; Chin-Guo Kuo; Mu-Jung Kao; Kuohsiu-David Huang; Kung-Hui Chu; Xiu-Ping Lin

2011-01-01

401

Optimization and application of TiO2/Ti-Pt photo fuel cell (PFC) to effectively generate electricity and degrade organic pollutants simultaneously.  

PubMed

A TiO2/Ti-Pt photo fuel cell (PFC) was established to generate electricity and degrade organic pollutants simultaneously. The electricity generation was optimized through investigation the influences of photoanode calcination temperature and dissolve oxygen on the resistances existing in PFC. TiO2 light quantum yield was also improved in PFC which resulted in a higher PC degradation efficiency. Two kinds of real textile wastewaters were also employed in this PFC system, 62.4% and 50.0% Coulombic efficiency were obtained for 8 h treatment. These refractory wastewaters with high salinity may become good fuels in PFC because a) TiO2 has no selectivity and can degrade nearly any organic substance, b) no more electrolyte is needed due to the high salinity, c) the energy in wastes can be recovered to generate electricity. The electricity generated by the PFC was further applied on a TiO2/Ti rotating disk photoelectrocatalytic reactor. A bias voltage between 0.6 and 0.75 V could be applied and the PC degradation efficiency was significantly improved. This result was similar with that obtained by a 0.7 V DC power. PMID:24926902

Li, Kan; Zhang, Hongbo; Tang, Tiantian; Xu, Yunlan; Ying, Diwen; Wang, Yalin; Jia, Jinping

2014-10-01

402

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

2013-10-21

403

Anatase TiO2 nanorod-decoration for highly efficient photoenergy conversion  

NASA Astrophysics Data System (ADS)

In recent studies of inorganic materials for energy applications, surface modification processes have been shown to be among the most effective methods to enhance the performance of devices. Here, we demonstrate a facile nano-decoration method which is generally applicable to anatase TiO2 nanostructures, as well as a nano-decorated hierarchical TiO2 nanostructure which improves the energy conversion efficiency of a dye-sensitized solar cell (DSSC). Using a facile sol-gel method, 0-D, 1-D, and 2-D type anatase TiO2 nanostructures were decorated with 200 nm long anatase TiO2 nanorods to create various hierarchical nanostructures. A structural analysis reveals that the branched nanorod has a highly crystalline anatase phase with anisotropic growth in the [001] longitudinal direction. When one of the hierarchical structures, a chestnut bur-like nanostructure, was employed in a dye-sensitized solar cell as a scattering layer, offering increased dye-loading properties, preserving a sufficient level of light-scattering ability and preserving superior charge transport and recombination properties as well, the energy conversion efficiency of the cell improved by 19% (from 7.16% to 9.09%) compared to a cell with a 0-D TiO2 sphere as a scattering layer. This generally applicable anatase nanorod-decorating method offers potential applications in various energy-conversion applications, especially in DSSCs, quantum-dot solar cells, photoelectrochemical water-splitting devices, photocatalysis, and lithium ion batteries.In recent studies of inorganic materials for energy applications, surface modification processes have been shown to be among the most effective methods to enhance the performance of devices. Here, we demonstrate a facile nano-decoration method which is generally applicable to anatase TiO2 nanostructures, as well as a nano-decorated hierarchical TiO2 nanostructure which improves the energy conversion efficiency of a dye-sensitized solar cell (DSSC). Using a facile sol-gel method, 0-D, 1-D, and 2-D type anatase TiO2 nanostructures were decorated with 200 nm long anatase TiO2 nanorods to create various hierarchical nanostructures. A structural analysis reveals that the branched nanorod has a highly crystalline anatase phase with anisotropic growth in the [001] longitudinal direction. When one of the hierarchical structures, a chestnut bur-like nanostructure, was employed in a dye-sensitized solar cell as a scattering layer, offering increased dye-loading properties, preserving a sufficient level of light-scattering ability and preserving superior charge transport and recombination properties as well, the energy conversion efficiency of the cell improved by 19% (from 7.16% to 9.09%) compared to a cell with a 0-D TiO2 sphere as a scattering layer. This generally applicable anatase nanorod-decorating method offers potential applications in various energy-conversion applications, especially in DSSCs, quantum-dot solar cells, photoelectrochemical water-splitting devices, photocatalysis, and lithium ion batteries. Electronic supplementary information (ESI) available: XRD of three types of TiO2 hosts, TEM images of nanorod-decorated TiO2 hierarchical nanostructures and host 0S-TiO2, reflectance of the free-standing TiO2 nanorod, SEM images of photoelectrodes employing various scattering layers with tmax, the amount of adsorbed dye molecules per surface volume on 0S and BS monolayer films, J-V curves of the DSSCs employing each active layer with tmax thickness, the transport time constants and recombination time constants versus various scattering layer thicknesses at constant Jsc (Jsc = 0.5 mA cm-2) and the photovoltaic parameters of each DSSC employing each tmax of various scattering layers. See DOI: 10.1039/c3nr03439a

Kim, Dong Hoe; Seong, Won Mo; Park, Ik Jae; Yoo, Eun-Sang; Shin, Seong Sik; Kim, Ju Seong; Jung, Hyun Suk; Lee, Sangwook; Hong, Kug Sun

2013-11-01

404

Micro-solid phase equilibrium extraction with highly ordered TiO 2 nanotube arrays: a new approach for the enrichment and measurement of organochlorine pesticides at trace level in environmental water samples  

Microsoft Academic Search

Ordered TiO2 nanotube arrays have been widely used in many fields such as photocatalysis, self-cleaning, solar cells, gas sensing, and\\u000a catalysis. This present study exploited a new functional application of the ordered TiO2 nanotube arrays. A micro-solid phase equilibrium extraction using ordered TiO2 nanotube arrays was developed for the enrichment and measurement of organochlorine pesticides prior to gas chromatography-electron\\u000a capture

Qingxiang Zhou; Yunrui Huang; Junping Xiao; Guohong Xie

2011-01-01

405

Synthesis and characterization of Pt-MoO x -TiO2 electrodes for direct ethanol fuel cells  

NASA Astrophysics Data System (ADS)

To enhance the CO-tolerance performance of anode catalysts for direct ethanol fuel cells, carbon nanotubes were modified by titanium dioxide (donated as CNTs@TiO2) and subsequently served as the support for the preparation of Pt/CNTs@TiO2 and Pt-Mo/CNTs@TiO2 electrocatalysts via a UV-photoreduction method. The physicochemical characterizations of the catalysts were carried out by using X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and infrared spectroscopy of adsorbed probe ammonia molecules. The electrocatalytic properties of the catalysts for methanol oxidation were investigated by the cyclic voltammetry technique. The results show that Pt-Mo/CNTs@TiO2 electrode exhibits the highest performance in all the electrodes. It is explained that, the structure, the oxidation states, and the acid-base properties of the catalysts are influenced due to the strong interaction between Ti and Mo species by adding TiO2 and MoO x to the Pt-based catalysts.

Wang, Xiu-Yu; Zhang, Jing-Chang; Cao, Xu-Dong; Jiang, Yuan-Sheng; Zhu, Hong

2011-10-01

406

TiO_{2}.  

PubMed

Using first-principles density functional theory calculations, we explore the chemical activity of epitaxial heterostructures of TiO_{2} anatase on strained polar SrTiO_{3} films focusing on the oxygen evolution reaction (OER), the bottleneck of water splitting. Our results show that the reactivity of the TiO_{2} surface is tuned by electric dipoles dynamically induced by the adsorbed species during the intermediate steps of the reaction while the initial and final steps remain unaffected. Compared to the OER on unsupported TiO_{2}, the combined effects of the dynamically induced dipoles and epitaxial strain strongly reduce rate-limiting thermodynamic barriers and significantly improve the efficiency of the reaction. PMID:24877949

Lee, Jun Hee; Selloni, Annabella

2014-05-16

407

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

408

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

409

Design and fabrication of nanometric TiO2/Ag/TiO2/Ag/TiO2 transparent conductive electrode for inverted organic photovoltaic cells application  

NASA Astrophysics Data System (ADS)

In this study, transparent conductive TiO2/Ag/TiO2/Ag/TiO2 (TATAT) nano-multilayer system is designed and optimum thickness of TiO2 and Ag layers are calculated. TATAT nano-multilayer films were deposited on glass substrates at room temperature by a thermal evaporation technique. We investigated some electrical, optical and structural properties of optimized TATAT multilayer such as sheet resistance, optical transmittance and the root-mean-square surface roughness. Here, we suggest a very low resistance transparent electrode (2.3 (?/?)) with a high transmittance (90%) for optoelectronics applications. Inverted organic photovoltaic cell was fabricated on the TATAT cathode. The fabricated cell with 12 nm of Ag layer shows higher power conversion efficiency (2.68%) compared to that fabricated on the ITO electrode (1.84%). The results show that the TATAT multilayer system is a suitable structure for use as transparent conductive electrode in optoelectronic devices.

Ghasemi Varnamkhasti, Mohsen; Shahriari, Esmaeil

2014-05-01

410

Nanopatterning of spin-coatable TiO2 resist using an electron beam  

NASA Astrophysics Data System (ADS)

Titanium dioxide has shown its potential application in solar cells, optical waveguides, gas sensors and photochromic devices. One of the hindrances for miniaturization of these devices is the lack of an easy and reliable way of patterning TiO2. In this paper, we describe a simple process of electron beam patterning of TiO2 using a spin-coatable TiO2 resist prepared by reacting titanium n-butoxide with benzoylacetone in isopropyl alcohol. The sensitivity of ~115 nm thick spin-coatable TiO2 resist is ~30 mC cm-2, which is ~107 times higher than sputtered TiOx and crystalline TiO2 films. Exposure to an electron beam results in the gradual removal of organic material from the resist. This makes the exposed resist insoluble in organic solvents such as acetone; thereby providing high resolution negative line patterns as small as 19 nm wide. Heating of the patterned films results in pure TiO2.

Saifullah, Mohammad S.; Welland, Mark E.

2003-06-01

411

Bioactivity and osteogenic cell response of TiO2 nanotubes coupled with nanoscale calcium phosphate via ultrasonification-assisted electrochemical deposition  

NASA Astrophysics Data System (ADS)

Ultrasonification-assisted electrochemical deposition was used to introduce nanoscale calcium phosphate (CaP) into well-ordered TiO2 nanotube arrays (NTA) fabricated by anodic oxidation. Field emission scanning electron microscopy, energy dispersive spectroscopy, X-ray diffraction, and a drop-shape analysis system were used to investigate the morphology, constituent components and hydrophilicity of the nanostructured CaP/NTA surface. Bioactivity and osteogenic cell response were also characterized by hydroxyapatite (HA) formation tests, protein adsorption tests, and in vitro preosteoblast culture experiments. Abundant acicular nanoscale calcium phosphate was successfully deposited on the inner and outer walls of the nanotubes. After immersion in simulated body fluid, increased hydroxyapatite formation was apparent on the surface of TiO2 nanotubes coupled with nanoscale CaP when compared to simple nanotube structures and polished titanium. The CaP/NTA surface also adsorbed a greater amount of protein after being exposed to bovine serum albumin solution. During cell culture experiments, the preosteoblasts exhibited enhanced cellular adhesion, proliferation, and differentiation on the CaP/NTA surfaces. The results demonstrate that the introduction of nanoscale calcium phosphate into self-organized TiO2 nanotubes via a straightforward ultrasonification-assisted deposition technique enhances the bioactivity and osteogenic cell response, owing to the combined effects of the nanostructured surface topography, chemical composition, and hydrophilicity.

Chen, Jianyu; Zhang, Zhiguang; Ouyang, Jianglin; Chen, Xianshuai; Xu, Zhewu; Sun, Xuetong

2014-06-01

412

Role of Reduced Graphene Oxide in the Critical Components of a CdS-Sensitized TiO2 -Based Photoelectrochemical Cell.  

PubMed

Nitrogen (N)-doped reduced graphene oxide (nRGO) is systematically incorporated into a TiO2 -CdS photoelectrochemical (PEC) cell and its role is examined in the three main components of the cell: 1) the CdS-sensitized TiO2 photoanode, 2) the cathode, and 3) the S(2-) /S(.-) aqueous redox electrolyte. The nRGO layer is sandwiched between TiO2 nanorods (deposited by using a solvothermal method) and CdS (deposited by using the successive ionic-layer-adsorption and -reaction method). Scanning electron microscopy with energy dispersive X-ray analysis (EDS) reveals the spatial distribution of CdS and nRGO, whereas nRGO formation is evident from Mott Schottky analysis. Chronoamperometry and PEC analysis indicate that upon incorporation of nRGO, a photocurrent density that is at least 27 times higher than that of pristine TiO2 is achieved; this increase is attributable to the ability of the nRGO to efficiently separate and transport charges. Stability analysis performed by continuous photoillumination over ?3 h indicates a 26% and 42?% reduction in the photocurrent in the presence and absence of the nRGO respectively. Formation of SO4 (2-) is identified as the cause for this photocurrent reduction by using X-ray photoelectron spectroscopy. It is also shown that nRGO-coated glass is as effective as a Pt counter electrode in the PEC cell. Unlike the benefits offered by nRGO at the anode and cathode, introducing it in the redox electrolyte is detrimental. Systematic and complementary electrolyte and film-based studies on this aspect reveal evidence of the capacitive behavior of nRGO. Competition between the nRGO and the oxidized electrolyte is identified, based on linear-sweep voltammetry analysis, as the limiting step to efficient charge transport in the electrolyte. PMID:24976600

Selvaraj, Josephine; Gupta, Satyajit; DelaCruz, Steven; Subramanian, Vaidyanathan Ravi

2014-07-21

413

Supramolecular solar cells  

NASA Astrophysics Data System (ADS)

Supramolecular chemistry - chemistry of non-covalent bonds including different type of intermolecular interactions viz., ion-pairing, ion-dipole, dipole-dipole, hydrogen bonding, cation-pi and Van der Waals forces. Applications based on supramolecular concepts for developing catalysts, molecular wires, rectifiers, photochemical sensors have been evolved during recent years. Mimicking natural photosynthesis to build energy harvesting devices has become important for generating energy and solar fuels that could be stored for future use. In this dissertation, supramolecular chemistry is being explored for creating light energy harvesting devices. Photosensitization of semiconductor metal oxide nanoparticles, such as titanium dioxide (TiO2) and tin oxide (SnO2,), via host-guest binding approach has been explored. In the first part, self-assembly of different porphyrin macrocyclic compounds on TiO2 layer using axial coordination approach is explored. Supramolecular dye sensitized solar cells built based on this approach exhibited Incident Photon Conversion Efficiency (IPCE) of 36% for a porphyrin-ferrocene dyad. In the second part, surface modification of SnO2 with water soluble porphyrins and phthalocyanine resulted in successful self-assembly of dimers on SnO2 surface. IPCE more than 50% from 400 - 700 nm is achieved for the supramolecular self-assembled heterodimer photocells is achieved. In summary, the axial ligation and ion-pairing method used as supramolecular tools to build photocells, exhibited highest quantum efficiency of light energy conversion with panchromatic spectral coverage. The reported findings could be applied to create interacting molecular systems for next generation of efficient solar energy harvesting devices.

Subbaiyan, Navaneetha Krishnan

414

Exploring the critical dependence of adsorption of various dyes on the degradation rate using Ln3+-TiO2 surface under UV/solar light  

NASA Astrophysics Data System (ADS)

The degradation of structurally different anionic dyes like Alizarin Red S (ARS) Amaranth (AR), Brilliant Yellow (BY), Congo Red (CR), Fast Red (FR), Methyl Orange (MO), and Methyl Red (MR) were carried out using Ln3+ (Ln3+ = La3+, Ce3+ and Gd3+) doped TiO2 at different pH conditions under UV/solar light. All the anionic dyes underwent rapid degradation at acidic pH, while resisted at alkaline conditions due to the adsorptive tendency of these dyes on the catalyst surface at different pH conditions. Gd3+ (0.15 mol%)-TiO2 exhibited better activity compared to other photocatalyst ascribed to half filled electronic configuration of Gd3+ ions. It is proposed that Ln3+ serves only as charge carrier traps under UV light, while it also act as visible light sensitizers under solar light. Irrespective of the catalyst and excitation source, the dye degradation followed the order: AR > FR > MO > MR > ARS > BY > CR. The results suggest that pre-adsorption of the pollutant is vital for efficient photocatalysis which is dependent on the nature of the substituent's group attached to the dye molecule.

Devi, L. Gomathi; Kumar, S. Girish

2012-11-01

415

Surface treatment of dye-sensitized solar cell using dielectric barrier discharge  

NASA Astrophysics Data System (ADS)

We have developed surface treatment of dye-sensitized solar cell (DSSC) using dielectric barrier discharge (DBD). The DSSC consists of TiO2 nanoporous photoelectrode sensitized with dye. The photoelectrode is a 10-?m thick film made by sintering TiO2 paste on a conductive glass substrate at 450 C. After the sintering, the TiO2 film is dipped into dye solution for sensitization. The DBD treatment is applied to the TiO2 film after the sintering. The DBD treatment improves the energy conversion efficiency, ?, by a factor of 1.05 to 1.15 depending on humidity and O2 concentration. It can be deduced that radicals such as O, O3, and OH contribute to the DBD treatment. The DBD treatment also has an effect of reducing the sintering temperature of TiO2 paste. If the TiO2 paste is sintered at much lower than 450 C (i.e. <=300 C), a solar cell cannot be produced, that is, ?= 0%. However, if the DBD treatment is applied after the low temperature sintering, a solar cell can be produced. This is important because the low-temperature sintering enables us to use materials that cannot resist high temperature. The DBD treatment is also applied to a plastic substrate DSSC. But the DBD causes damage on the TiO2 film and at present it is not suceeded.

Ono, Ryo; Zen, Shungo; Teramoto, Yoshiyuki; Hanawa, Keisuke; Kobayashi, Soichi; Oda, Tetsuji

2012-10-01

416

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

417

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

418

One-pot synthesis of N-F-Cr-doped anatase TiO2 microspheres with nearly all-(001) surface for enhanced solar absorption  

NASA Astrophysics Data System (ADS)

The synthesis and clarifications in structure-property relationship for anatase TiO2 crystals exposing (001) facets have attracted much attention. In this paper, a novel titania microsphere with nearly all-(001) surface was synthesized by hydrothermal treatment of a thermal sprayed TiN/Ti coating with HF aqueous solution containing chromium powders. Unlike the conventional (001)-facet exposed anatase crystals, which are highly truncated bipyramids, the crystal achieved in the current investigation is drum-like with a round cross section. The formation of the drum-like crystals was contributed to a balance between the erosion and precipitation of anatase single crystallites. The Cr-doping in anatase was believed to increase the surface deficiency which enhanced the erosion procedure, leading to the drum-like crystals. The XPS analysis confirmed the incorporations of N, F and Cr in the microsized anatase crystals through the one-pot reaction, which led to a significantly enhanced solar absorption. The UV-Vis diffuse reflectance revealed a band-to-band red-shift of the band gap of the anatase crystals to 1.60 eV, which is contributed mainly to the homogeneous Cr-doping.The synthesis and clarifications in structure-property relationship for anatase TiO2 crystals exposing (001) facets have attracted much attention. In this paper, a novel titania microsphere with nearly all-(001) surface was synthesized by hydrothermal treatment of a thermal sprayed TiN/Ti coating with HF aqueous solution containing chromium powders. Unlike the conventional (001)-facet exposed anatase crystals, which are highly truncated bipyramids, the crystal achieved in the current investigation is drum-like with a round cross section. The formation of the drum-like crystals was contributed to a balance between the erosion and precipitation of anatase single crystallites. The Cr-doping in anatase was believed to increase the surface deficiency which enhanced the erosion procedure, leading to the drum-like crystals. The XPS analysis confirmed the incorporations of N, F and Cr in the microsized anatase crystals through the one-pot reaction, which led to a significantly enhanced solar absorption. The UV-Vis diffuse reflectance revealed a band-to-band red-shift of the band gap of the anatase crystals to 1.60 eV, which is contributed mainly to the homogeneous Cr-doping. Electronic supplementary information (ESI) available: 4 figures to support our discussion. See DOI: 10.1039/c1nr10737b

Wu, Jin-Ming; Tang, Mei-Lan

2011-09-01

419

Fabrication and optical properties of conjugated polymer composited multi-arrays of TiO2 nanowires via sequential electrospinning.  

PubMed

We report here a simple method of fabricating multi-layered architectures of cross-aligned inorganic nanowires via sequential electrospinning method equipped with a newly devised collector that is able to prepare aligned inorganic nanowires. The multi-layers of aligned TiO2 nanowires can be deposited in a proportional increment of weight with collecting time and reveal a large reduction of electrical resistance by at least 30% compared to a randomly collected TiO2 nanowire structure. The solar cell performance of the cross-aligned TiO2 nanowire layers composited with a conjugated polymer of poly[2-methoxy, 5-(2'-ethyl-hexyloxy)-1,4-phenylenevinylene] (MEH-PPV) is significantly enhanced by 70% or greater in the organic-inorganic hybrid photovoltaic devices than that fabricated with the randomly-collected TiO2 nanowire photoanode. PMID:19928140

Shim, Hee-Sang; Kim, Jeong Won; Kim, Won Bae

2009-08-01

420

Insights into solar TiO2-assisted photocatalytic oxidation of two antibiotics employed in aquatic animal production, oxolinic acid and oxytetracycline.  

PubMed

In this study, solar driven TiO2-assisted heterogeneous photocatalytic experiments in a pilot-plant with compound parabolic collectors (CPCs) were carried out to study the degradation of two authorized veterinary antibiotics with particular relevance in finfish aquaculture, oxolinic acid (OXA) and oxytetracycline (OTC), using pure solutions of individual or mixed antibiotics. Firstly, the influence of natural solar photolysis was assessed for each antibiotic. Secondly, photocatalytic degradation kinetic rate constants for individual and mixed antibiotics were compared, using a catalyst load of 0.5 g L(-1) and an initial pH around 7.5. Thirdly, for individually photocatalytic-treated OXA and OTC in the same conditions, the growth inhibition of Escherichia coli DSM 1103 was followed, and the mineralization extent was assessed by the residual dissolved organic carbon (DOC), low-molecular-weight carboxylate anions and inorganic ions concentration. Finally, the effect of inorganic ions, such as chlorides, sulfates, nitrates, phosphates, ammonium and bicarbonates, on the photocatalytic degradation of individual solutions of OXA and OTC was also evaluated and the formation of different reactive oxygen species were probed using selective scavengers. The removal profiles of each antibiotic, both as single component or in mixture were similar, being necessary 2.5 kJ L(-1) of solar UV energy to fully remove them, and 18 kJ(UV) L(-1) to achieve 73% and 81% mineralization, for OXA and OTC, respectively. The remaining organic carbon content was mainly due to low-molecular-weight carboxylate anions. After complete removal of the antibiotics, the remaining degradation by-products no longer showed antibacterial activity. Also, 10% and 55% of the nitrogen content of each antibiotic was converted to ammonium, while no conversion to nitrite or nitrate was detected. The presence of phosphates hindered considerably the removal of both antibiotics, whereas the presence of other inorganic ions did not substantially altered the antibiotics photocatalytic degradation kinetics. PMID:23816421

Pereira, João H O S; Reis, Ana C; Queirós, Daniel; Nunes, Olga C; Borges, Maria T; Vilar, Vítor J P; Boaventura, Rui A R

2013-10-01

421

The influence of Yb, B, and Ga-doped Er3+:Y3Al5O12 on solar light photocatalytic activity of TiO2 in degradation of organic dyes  

NASA Astrophysics Data System (ADS)

Five up-conversion luminescence agents (Er3+:Y3Al5O12, Er3+:Yb n Y3 - n Al5O12, Er3+:Y3B a Al5 - a O12, Er3+:Y3Ga b Al5 - b O12, and Er3+:Yb n Y3 - n B a Ga b Al5 - a - b O12) were synthesized using sol-gel method and then the corresponding coated composites (Er3+:Y3Al5O12/TiO2, Er3+:Yb n Y3- n Al5O12/TiO2, Er3+:Y3B a Al5 - a O12/TiO2, Er3+:Y3Ga b Al5 - b O12/TiO2, and Er3+:Yb n Y3 - n B a Ga b Al5 - a - b O12/TiO2) as photocatalysts were prepared by sol-gel coating process. The XRD and SEM were used to confirm the crystalline phase and surface morphology. The UV-vis absorption and fluorescence-emission spectra were used to research the effect of doping category and amount on the up-conversion emission ability. The photocatalytic activities were detected through the degradation of Acid Red B dye in aqueous solution. Some key parameters of catalyst amount and initial concentration of organic dye on solar light photocatalytic degradation were also examined. The extensive feasibility of prepared photocatalysts in solar light degradation was detected by other organic dyes. The results suggest that the photocatalysts can be widely used in sewage treatment.

Wang, J.; Li, Y.; Wang, J.; Zhang, L.; Gao, J. Q.; Wang, B. X.; Yang, Q.; Fan, P.

2014-01-01

422

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

423

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

PubMed

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). PMID:23712615

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

2013-07-01

424

On the photophysical and electrochemical studies of dye-sensitized solar cells with the new dye CYC-B1  

Microsoft Academic Search

In this study, the photoelectrochemical characteristics of a ruthenium photosensitizer with an alkyl bithiophene group, designated as CYC-B1, are studied. The effect of mesoporous TiO2 film thickness on the photovoltaic performance of CYC-B1 and N3 dye-sensitized solar cells was investigated. The performance of the dye-sensitized nanocrystalline TiO2 solar cells (DSSC) fabricated using CYC-B1 dye-anchored TiO2 photoelectrode showed a convincing enhancement

Jian-Ging Chen; Chia-Yuan Chen; Shi-Jhang Wu; Jheng-Ying Li; Chun-Guey Wu; Kuo-Chuan Ho

2008-01-01

425

Visible photocurrent response of TiO 2 anode  

NASA Astrophysics Data System (ADS)

The photoelectrochemical response to the electromagnetic radiation over the visible range is particularly sought for from the point of view of the efficiency of hydrogen generation by water photolysis in a photoelectrochemical solar cell, PEC. The PEC used in this work comprises thin film TiO 2 - based photoanode, Pt foil covered with Pt black as a cathode and SCE as a reference electrode, immersed in an electrolyte solution. Titanium dioxide thin films are deposited by means of rf reactive sputtering and modified, when necessary, by Au or Ag ultra-thin overcoatings. Here we show that even unmodified TiO 2 photoanode, shows a photocurrent peak over the visible range of the light spectrum ( ? = 500-650 nm). The effect of the surface modification by noble metals and properties of the aqueous electrolyte on the visible photocurrent are studied. The optical spectra indicate an increased absorption due to noble metal deposits at 410 nm for Ag and at 600 nm for Au. In contrast, the photocurrent peak over the visible range (500 nm < ? < 650 nm) changes its symmetry and decreases in intensity with the increasing thickness of noble metals layers. The visible photoresponse is explained in terms of OH formation at the interface between TiO 2 electrode and aqueous electrolyte.

Gorzkowska–Sobas, A.; Kusior, E.; Radecka, M.; Zakrzewska, K.

2006-09-01

426