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1

Solar Energy Materials & Solar Cells 71 (2002) 261271 Photoelectric behavior of nanocrystalline TiO2  

E-print Network

Solar Energy Materials & Solar Cells 71 (2002) 261­271 Photoelectric behavior of nanocrystalline Ti; received in revised form 18 April 2001; accepted 30 May 2001 Abstract The photoelectric behavior of a black. A sandwich-type solar cell fabricated by this dye-sensitized nanocrystalline TiO2 film generated 6:1 mA cm�2

Huang, Yanyi

2

Rutile TiO2 nanowire-based perovskite solar cells.  

PubMed

Different lengths of rutile TiO2 nanowires (NW) with wide-open space for effective material filling were used as photoanodes for perovskite solar cells. Cells with 900 nm nanowires as photoanodes exhibit a current density of 22 mA cm(-2) and an efficiency of 11.7%, outperforming the reported TiO2 nanowire-based perovskite solar cells. PMID:25317656

Jiang, Qinglong; Sheng, Xia; Li, Yingxuan; Feng, Xinjian; Xu, Tao

2014-12-01

3

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

NASA Astrophysics Data System (ADS)

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

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

2014-10-01

4

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

5

Chemical bath deposited CdS\\/CdSe-sensitized porous TiO 2 solar cells  

Microsoft Academic Search

CdSe is homogeneously deposited into nanoporous TiO2 films and used in liquid junction photoelectrochemical solar cells. The effect of the deposition parameters on the cell are studied, in particular differences between ion-by-ion and cluster deposition mechanisms. CdSe deposition on a Cd-rich CdS film that was deposited first into the TiO2 film, or selenization of the Cd-rich CdS layer with selenosulphate

Olivia Niitsoo; Shaibal K. Sarkar; Christophe Pejoux; Sven Rühle; David Cahen; Gary Hodes

2006-01-01

6

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

7

Interface modifications in solid state dye-sensitized TiO2 solar cells  

Microsoft Academic Search

The concept of solid-state dye-sensitized TiO2 solar cell in which the hole transport medium is an organic semiconductor is critically studied by examining the anode-TiO2 interface and dye-hole conductor interface. The importance and the role of a compact hole-blocking TiO2 layer in between the anode and the mesoporous layer is extensively studied by preparing this layer by spray pyrolysis using

Bin Peng; Katja Peter; Helga Wietasch; Mukundan Thelakkat

2004-01-01

8

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

Microsoft Academic Search

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

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

2008-01-01

9

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

10

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

11

Nanostructured TiO2 films for dye-sensitized solar cells  

NASA Astrophysics Data System (ADS)

A new strategy was attempted to fabricate photoelectrode of dye-sensitized solar cells through a reassembly technique (exfoliation and restacking) to increase solar activity. A random hybridization between exfoliated layered titanate and TiO2 (anatase) nanoparticles resulted in a ‘house-of-cards’ structure, which might increase the mesoporosity and surface area of TiO2 film. In the XRD patterns of the present nanocomposite, no (00 l) peaks could be seen due to the random hybridization between layered titanate and TiO2 nanosol particles. According to the N2 adsorption desorption isotherms, the resulting nanohybrids are fairly porous with a high specific surface area (SBET=˜190 m2/g, mean pore size=6 nm), which leads to an efficient dye adsorption. A solar energy to electricity conversion efficiency (?) of the present nanocomposite film is about 100 times higher than that of TiO2 nanoparticle one under the standard AM 1.0 irradiation condition, suggesting that the mesoporous nature of TiO2 film would play an important role for efficient photovoltaic cell performance.

Paek, Seung-Min; Jung, Hyun; Lee, Young-Jun; Park, Nam-Gyu; Hwang, Seong-Ju; Choy, Jin-Ho

2006-05-01

12

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

PubMed

The optimization of dye-sensitized solar cells, especially the design of nanoporous TiO2 film microstructure, is an urgent problem for high efficiency and future commercial applications. However, up to now, little attention has been focused on the design of nanoporous TiO2 microstructure for a high efficiency of dye-sensitized solar cell modules. The optimization and design of TiO2 photoelectrode microstructure are discussed in this paper. TiO2 photoelectrodes with three different layers, including layers of small pore size films, larger pore size films, and light-scattering particles on the conducting glass with the desirable thickness, were designed and investigated. Moreover, the photovoltaic properties showed that the different porosities, pore size distribution, and BET surface area of each layer have a dramatic influence on short-circuit current, open-circuit voltage, and fill factor of the modules. The optimization and design of TiO2 photoelectrode microstructure contribute a high efficiency of DSC modules. The photoelectric conversion efficiency around 6% with 15 x 20 cm2 modules under illumination of simulated AM1.5 sunlight (100 mW/cm2) and 40 x 60 cm2 panels with the same performance tested outdoor have been achieved by our group. PMID:17214486

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

2007-01-18

13

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

14

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

NASA Astrophysics Data System (ADS)

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

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

2014-09-01

15

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. PMID:23181192

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

16

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

NASA Astrophysics Data System (ADS)

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

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

2015-01-01

17

Comparative study of TiO2 nanoparticles applied to dye-sensitized solar cells  

NASA Astrophysics Data System (ADS)

Microcrystalline titanium oxide (TiO2) particles of anatase crystal phase were prepared by the sol-gel route, varying thermal treatment conditions (400 °C and 600 °C), for a comparison purpose with commercial TiO2 (P25). Structural, optical and electrical properties were investigated for dye-sensitized solar cells (DSSCs) application. Both microcrystalline TiO2 particles, synthesized by the sol-gel method and obtained from the P25 powder were used to prepare a light scattering layer of the working electrode. The obtained electrodes were then immersed in a solution of N-719 (ruthenium) dye, at the ambient temperature, during 24 h. Finally, the DSSCs were assembled, the short circuit photocurrent, the open circuit photovoltage, and the power conversion efficiency were measured using an I-V measurement system. The overall conversion efficiencies for all elaborated DSSCs were proximate. A maximum efficiency of 2.3% was achieved for the sol-gel TiO2 thin film annealed at 400 °C, under one sun irradiation, with an open circuit voltage of 0.61 V and a current density of 6.54 mA/cm2. The higher efficiency value of the sol-gel TiO2 sample, annealed at 400 °C, was attributed to the uniformity of the prepared titanium oxide substrate, which provides a better surface for the dye absorption.

Yacoubi, Besma; Bennaceur, Jamila; Ben Taieb, S.; Chtourou, Rathowan

2014-02-01

18

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

19

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

NASA Astrophysics Data System (ADS)

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

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

2013-12-01

20

Preparation of flexible TiO2 photoelectrodes for dye-sensitized solar cells  

NASA Astrophysics Data System (ADS)

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

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

2014-09-01

21

Interface modifications in solid state dye-sensitized TiO2 solar cells  

NASA Astrophysics Data System (ADS)

The concept of solid-state dye-sensitized TiO2 solar cell in which the hole transport medium is an organic semiconductor is critically studied by examining the anode-TiO2 interface and dye-hole conductor interface. The importance and the role of a compact hole-blocking TiO2 layer in between the anode and the mesoporous layer is extensively studied by preparing this layer by spray pyrolysis using an automated procedure which guarantees reproducibility in obtaining constant thickness and quality of this crucial layer as seen in the current-voltage characteristics of the solar cells. To characterize the rectifying behavior of the blocking layer, cells with the structure, fluorinated tin oxide (FTO)/blocking TiO2 layer/hole conductor/Au, were prepared and their current (I)-voltage (U) properties were investigated. Solid state solar cells were also prepared with different blocking layer thicknesses and their photovoltaic properties were investigated in order to study the influence of the blocking layer thickness on solar cell performance. In order to improve the dye-hole conductor interface, novel multifunctional molecules carrying dye units and triphenylamine moieties were synthesized and their influence as interface modifiers were studied. This interface modification results in doubling the external quantum efficiency of current conversion via improved charge transfer at the dye-hole conductor interface. Moreover, the recombination processes at this interface is drastically suppressed which leads to higher open circuit voltage and consequently higher power conversion efficiencies.

Peng, Bin; Peter, Katja; Wietasch, Helga; Thelakkat, Mukundan

2004-02-01

22

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. PMID:23421351

2013-01-01

23

A Comparative Study of Nanostructured TiO2, ZnO and Bilayer TiO2/ZnO Dye-Sensitized Solar Cells  

NASA Astrophysics Data System (ADS)

Titanium dioxide (TiO2), Zinc oxide (ZnO) and bilayer TiO2/ZnO (TZO) based cells have been developed and sensitized with five organic dyes and one cocktail dye composed of five dyes. Photovoltaic performance of TiO2 and ZnO solar cell sensitized with six dyes is compared to that of bilayer TZO cells. The forward current is found to increase with applied voltage in the range V ? 0.4 V, which is dominated by thermionic emission, whereas in 0.4 ? V ? 0.7 V, the current transport is due to space charge-limited current controlled by exponential trap distribution in all devices. The combined properties of the materials enhance the efficiency of composite TZO cells. TiO2 permits the formation of an energy barrier at the ZnO electrode/electrolyte interface, which reduces the back electron transfer from the conduction band of ZnO to I3 - in the electrolyte. Also, due to the TiO2 layer on the ZnO, the latter forms a compact layer between flourine-doped tin oxide (FTO)/TiO2 which benefits the fast electron transfer from TiO2 to ZnO to FTO glass. This reduces the charge recombination occurring at the ZnO/FTO interface leading to higher open circuit voltage (V oc), higher short circuit current (J sc), lower series resistance (R s), and in turn higher efficiency in TZO solar cells as compared to ZnO cells. Among the six dyes, Eosin-Y and Rose Bengal dye gave the best performance as sensitizers with TZO.

Rani, Mamta; Tripathi, S. K.

2015-02-01

24

A Comparative Study of Nanostructured TiO2, ZnO and Bilayer TiO2/ZnO Dye-Sensitized Solar Cells  

NASA Astrophysics Data System (ADS)

Titanium dioxide (TiO2), Zinc oxide (ZnO) and bilayer TiO2/ZnO (TZO) based cells have been developed and sensitized with five organic dyes and one cocktail dye composed of five dyes. Photovoltaic performance of TiO2 and ZnO solar cell sensitized with six dyes is compared to that of bilayer TZO cells. The forward current is found to increase with applied voltage in the range V ? 0.4 V, which is dominated by thermionic emission, whereas in 0.4 ? V ? 0.7 V, the current transport is due to space charge-limited current controlled by exponential trap distribution in all devices. The combined properties of the materials enhance the efficiency of composite TZO cells. TiO2 permits the formation of an energy barrier at the ZnO electrode/electrolyte interface, which reduces the back electron transfer from the conduction band of ZnO to I3 - in the electrolyte. Also, due to the TiO2 layer on the ZnO, the latter forms a compact layer between flourine-doped tin oxide (FTO)/TiO2 which benefits the fast electron transfer from TiO2 to ZnO to FTO glass. This reduces the charge recombination occurring at the ZnO/FTO interface leading to higher open circuit voltage ( V oc), higher short circuit current ( J sc), lower series resistance ( R s), and in turn higher efficiency in TZO solar cells as compared to ZnO cells. Among the six dyes, Eosin-Y and Rose Bengal dye gave the best performance as sensitizers with TZO.

Rani, Mamta; Tripathi, S. K.

2015-04-01

25

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

NASA Astrophysics Data System (ADS)

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

Yu, Jiaguo; Fan, Jiajie; Lv, Kangle

2010-10-01

26

Comparison of the performances of dye-sensitized solar cells based on different TiO 2 electrode nanostructures  

Microsoft Academic Search

This article reports on the performances of dye-sensitized solar cells based on three different working electrode structures,\\u000a i.e., (i) sintered TiO2 nanoparticles (20–40 nm diameters), (ii) ordered arrays of TiO2 nanotubules (150 nm external diameters and 80 nm internal diameters), and (iii) ordered arrays of TiO2 nanorods (150 nm diameters). Even though the highest short-circuit current density was achieved with systems based on TiO2

Nicholas N. Bwana

2009-01-01

27

Rutile TiO2 nanorod array for high efficient dye sensitized solar cells  

NASA Astrophysics Data System (ADS)

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

Yang, Mengjin; Li, Wenzhi

2013-03-01

28

A parametric study of TiO2\\/CuInS2 nanocomposite solar cells: how cell thickness, buffer layer thickness, and TiO2 particle size affect performance  

Microsoft Academic Search

3D CuInS2\\/TiO2 nanocomposite solar cell performance is strongly influenced by several structural factors, including cell thickness, buffer layer thickness, and the morphology of the TiO2 nanoparticulate matrix. To delineate the effect of these structural factors on photovoltaic performance, a series of parametric studies are performed where a single structural parameter is varied (TiO2 nanoparticulate matrix thickness, In2S3 buffer layer thickness,

Ryan O’Hayre; Marian Nanu; Joop Schoonman; Albert Goossens

2007-01-01

29

Oxide thickness and roughness factor as parameters for TiO 2 -dye sensitized solar cells performance  

Microsoft Academic Search

Oxide surface roughness in connection to oxide thickness has proved to be a key parameter for the performance of a dye sensitised\\u000a solar cell. In this work, the numerical simulation of the system TiO2-photo sensitive dye of a dye sensitized TiO2 solar cell focuses on these two parameters. The steady-state numerical model used is based on the continuity and transport

P. H. Joshi; D. P. Korfiatis; S. F. Potamianou; K.-A. Th. Thoma

2011-01-01

30

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

PubMed

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

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

2011-12-01

31

Dye-sensitized TiO2 nanotube solar cells: fabrication and electronic characterization.  

PubMed

TiO2 nanotubes (TNTs) with large aspect ratio and large specific surface area were prepared from P25 (Nippon Aerosil) and applied to dye-sensitized titanium dioxide solar cells (DSSCs). Optimization of fabrication conditions, i.e., pH of the starting paste, sintering temperature for the TiO2 electrodes, electrolyte compositions of DSSCs gave the high conversion efficiency with improved open circuit voltage (V(oc)) and fill factor (FF) when compared to DSSCs made of P25. The evaluation of dye adsorption and the photo-injected electron transport such as electron diffusion coefficient (D) and electron lifetime (tau) in TNTs electrodes revealed that the higher efficiency resulted from increase of electron density with keeping much longer tau in TNTs electrodes than in P25 electrodes. PMID:16474882

Ohsaki, Yoshinori; Masaki, Naruhiko; Kitamura, Takayuki; Wada, Yuji; Okamoto, Takumi; Sekino, Toru; Niihara, Kohichi; Yanagida, Shozo

2005-12-21

32

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

33

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

PubMed Central

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

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

2013-01-01

34

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

35

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

NASA Astrophysics Data System (ADS)

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

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

2014-08-01

36

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

PubMed

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

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

2014-01-01

37

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

PubMed Central

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

2014-01-01

38

Activation energy of electron transport in dye-sensitized TiO2 solar cells.  

PubMed

Various characteristics of dye-sensitized nanostructured TiO2 solar cells, such as electron transport and electron lifetime, were studied in detail using monochromatic illumination conditions. The electron transport was found to be a thermally activated process with activation energies in the range of 0.10-0.15 eV for light intensities that varied 2 orders of magnitude. Electron lifetimes were determined using a new method and found to be significantly larger (>1 s) than previously determined. An average potential was determined for electrons in the nanostructured TiO2 under illumination in short-circuit conditions. This potential is about 0.2 V lower than the open-circuit potential at the same light intensity. The electron transport time varies exponentially with the internal potential at short-circuit conditions, indicating that the gradient in the electrochemical potential is the driving force for electron transport in the nanostructured TiO2 film. The applicability of the conventionally used trapping/detrapping model is critically analyzed. Although experimental results can be fitted using a trapping/detrapping model with an exponential distribution of traps, the distribution parameters differ significantly between different types of experiment. Furthermore, the experimental activation energies for electron transport are smaller than those expected in a trapping/detrapping model. PMID:16852492

Boschloo, Gerrit; Hagfeldt, Anders

2005-06-23

39

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

PubMed Central

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

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

2013-01-01

40

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

Microsoft Academic Search

This study investigates the applicability of n-type TiO2 and p-type NiO on the FTO-glass (Fluorine doped tin oxide, SnO2:F) substrate of the working electrode in a dye-sensitized solar cell (DSSC). The working electrode was designed and fabricated by depositing a film of TiO2\\/NiO composite particles, which were prepared by mixing the Ni powder with TiO2 particles using dry mixing method,

Chuen-Shii Chou; You-Jen Lin; Ru-Yuan Yang; Kuan-Hung Liu

2011-01-01

41

Rutile TiO 2 microspheres with exposed nano-acicular single crystals for dye-sensitized solar cells  

Microsoft Academic Search

Uniquely structured rutile TiO2 microspheres with exposed nano-acicular single crystals have been successfully synthesized via a facile hydrothermal method.\\u000a After calcination at 450 °C for 2 h, the rutile TiO2 microspheres with a high surface area of 132 m2\\/g have been utilized as a light harvesting enhancement material for dye-sensitized solar cells (DSSCs). The resultant DSSCs\\u000a exhibit an overall light

Haimin Zhang; Hua Yu; Yanhe Han; Porun Liu; Shanqing Zhang; Peng Wang; Yibing Cheng; Huijun Zhao

42

Surface Treatment of TiO2 Films by Pulse Plasma for Dye-Sensitized Solar Cells Application  

Microsoft Academic Search

Surface processing was studied using a dc atmospheric nonthermal plasma jet with nitrogen gas as a method for preparing the glass plate with a fluorine-dope-tin-oxide membrane, coated with titanium oxide (TiO2) and sintered at 450degC for dye-sensitized solar cells. The results showed that characteristics of the TiO2 surface were enhanced by the dc atmospheric nonthermal plasma jet and, hence, the

Toshifumi Yuji; Youl-Moon Sung

2007-01-01

43

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

44

Hyperbranched Quasi-1D TiO2 Nanostructure for Hybrid Organic-Inorganic Solar Cells.  

PubMed

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

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

2015-04-15

45

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

NASA Astrophysics Data System (ADS)

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

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

2014-03-01

46

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

PubMed

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

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

2014-01-01

47

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

NASA Astrophysics Data System (ADS)

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

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

2014-11-01

48

LiF-doped mesoporous TiO2 as the photoanode of highly efficient dye-sensitized solar cells  

NASA Astrophysics Data System (ADS)

This paper reports the doping of nanocrystalline TiO2 with LiF by mechanical grinding and subsequent sintering and the application of LiF-doped TiO2 as the photoanode of highly efficient dye-sensitized solar cells (DSCs). The fluoride ions can dope into the TiO2 matrix as revealed by X-ray photoelectron spectroscopy (XPS). The LiF-doped TiO2 samples are characterized by scanning electron microscopy (SEM), tunneling electron microscopy (TEM), X-ray diffraction (XRD), and UV-visible absorption spectroscopy. Doping of TiO2 with a small amount of LiF can improve the photovoltaic performance of DSCs. At the optimal LiF loading of 0.53 wt% in TiO2, the power conversion efficiency (PCE) of DSCs is enhanced from 7.74% to 8.24% under simulated AM1.5 illumination. The effect of the LiF doping on the photovoltaic performance of DSCs is investigated by electrochemical impedance spectroscopy (EIS) and incident photon conversion efficiency (IPCE) measurements. The improvement in the photovoltaic efficiency is attributed to the facilitation of the electron transport through the TiO2 electrode as a result of the increase in the anatase crystallinity induced by the LiF doping. The enhanced anatase crystallinity also causes a decrease in the charge recombination.

Neo, Chin Yong; Ouyang, Jianyong

2013-11-01

49

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

PubMed Central

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

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

2013-01-01

50

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

E-print Network

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

Wang, Zhong L.

51

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

NASA Astrophysics Data System (ADS)

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

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

2015-03-01

52

Rectangular bunched rutile TiO2 nanorod arrays grown on carbon fiber for dye-sensitized solar cells.  

PubMed

Because of their special application in photovoltaics, the growth of one-dimensional single-crystalline TiO(2) nanostructures on a flexible substrate is receiving intensive attention. Here we present a study of rectangular bunched TiO(2) nanorod (NR) arrays grown on carbon fibers (CFs) from titanium by a "dissolve and grow" method. After a corrosion process in a strong acid solution, every single nanorod is etched into a number of small nanowires. Tube-shaped dye-sensitized solar cells are fabricated by using etched TiO(2) NRs-coated CFs as the photoanode. An absolute energy conversion efficiency of 1.28% has been demonstrated under 100 mW cm(-2) AM 1.5 illumination. This work demonstrates an innovative method for growing bunched TiO(2) NRs on flexible substrates that can be applied in flexible devices for energy harvesting and storage. PMID:22300521

Guo, Wenxi; Xu, Chen; Wang, Xue; Wang, Sihong; Pan, Caofeng; Lin, Changjian; Wang, Zhong Lin

2012-03-01

53

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

54

Enhanced photovoltaic performance in TiO2/P3HT hybrid solar cell by interface modification  

NASA Astrophysics Data System (ADS)

A TiO2/P3HT hybrid solar cell was fabricated by infiltrating P3HT into the pores of TiO2 nanorod arrays. To further enhance the photovoltaic performance, anthracene-9-carboxylic acid was employed to modify the interface of TiO2/P3HT before P3HT was coated. Results revealed that the interface treatment significantly enhances the photovoltaic performance of the cell. The efficiency of the hybrid solar cells reaches 0.28% after interface modification, which is three times higher compared with the un-modified one. We find that except for the increased exciton dissociation efficiency recognized by the previous reports, the suppressing of electron back recombination is another important factor leading to the enhanced photovoltaic performance.

Duofa, Wang; Haizheng, Tao; Xiujian, Zhao; Meiyan, Ji; Tianjin, Zhang

2015-02-01

55

High Rate Reactive Sputter Deposition of TiO2 Films for Photocatalyst and Dye-Sensitized Solar Cells  

NASA Astrophysics Data System (ADS)

We fabricated dye-sensitized solar cells (DSCs) using TiO2 films deposited on various substrates by reactive magnetron sputtering with midfrequency pulsing and process control units, and evaluated their performance. Two pulse modes, i.e., unipolar pulse and pulse packet modes, were utilized to deposit TiO2. The highest conversion efficiency achieved was 3.7% when 10-µm-thick TiO2 films were deposited on glass substrates coated with fluorine-doped tin oxide (FTO) using the unipolar pulse mode in the oxide mode and postannealing in air. On the other hand, the conversion efficiency achieved was 2.7% for cells with 10-µm-thick TiO2 films deposited on glass substrates coated with FTO using the pulse packet mode without postannealing, and it dropped to 1.3% when the unipolar pulse mode was used. The relationships between the photocatalytic decomposition activity and the DSC characteristics with regard to the TiO2 films were investigated in detail. The reduction in the density of defects in the TiO2 films led to an improvement in both the photocatalytic activity and the DSC characteristics.

Sato, Yasushi; Hashimoto, Takahiro; Miyamura, Amica; Ohno, Singo; Oka, Nobuto; Suzuki, Koichi; Glöß, Daniel; Frach, Peter; Shigesato, Yuzo

2011-04-01

56

TiO2-based solar cells sensitized by chemical-bath-deposited few-layer MoS2  

NASA Astrophysics Data System (ADS)

Herein, we reported a novel MoS2/TiO2 heterostructure inorganic solar cell based on chemical-bath deposition of MoS2 in the mesoporous TiO2 three-dimensional network. Raman spectrum indicated the existence of MoS2 and suggested a few-layer structure with peaks at 384 cm-1 and 405.5 cm-1. HRTEM images further confirmed the few-layer structure of MoS2 (3-7 layers). With deposited MoS2, UV absorption spectra of TiO2 photoanode film indicated a considerably enhanced absorption in the visible region. Both annealing and careful control of the thickness of MoS2 sensitized layer could optimize the photovoltaic performance. The reason for the enhanced photovoltaic performance of the novel inorganic solar cell was also explained in detail.

Du, Tian; Wang, Ning; Chen, Haijun; He, Hongcai; Lin, Hong; Liu, Kai

2015-02-01

57

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

58

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

PubMed

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

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

2013-09-25

59

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

PubMed Central

TiO2 nanotube arrays are very attractive for dye-sensitized solar cells (DSSCs) owing to their superior charge percolation and slower charge recombination. Highly ordered, vertically aligned TiO2 nanotube arrays have been fabricated by a three-step anodization process. Although the use of a one-dimensional structure provides an enhanced photoelectrical performance, the smaller surface area reduces the adsorption of dye on the TiO2 surface. To overcome this problem, we investigated the effect of DSSCs constructed with a multilayer photoelectrode made of TiO2 nanoparticles and TiO2 nanotube arrays. We fabricated the novel multilayer photoelectrode via a layer-by-layer assembly process and thoroughly investigated the effect of various structures on the sample efficiency. The DSSC with a four-layer photoelectrode exhibited a maximum conversion efficiency of 7.22% because of effective electron transport and enhanced adsorption of dye on the TiO2 surface. PMID:25593557

2014-01-01

60

Electrospun TiO2 nanorods with carbon nanotubes for efficient electron collection in dye-sensitized solar cells.  

PubMed

A high power conversion efficiency of 10.24% can be obtained in a dye-sensitized solar cell by incorporating multiwall carbon nanotubes inside a TiO2 nanorod photoanode. The multiwall carbon nanotubes in the nanorod can effectively collect and transport photogenerated electrons reducing the recombination as well as improving efficiency of the device. PMID:23355287

Yang, Lijun; Leung, Wallace Woon-Fong

2013-03-25

61

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

PubMed Central

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

2012-01-01

62

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

63

Enhancing performance of P3HT:TiO2 solar cells using doped and surface modified TiO2 nanorods.  

PubMed

Here we demonstrated an approach to increase performance of P3HT:TiO2 solar cell either by electron deficient boron or electron rich bismuth doping into TiO2 nanorods. The B doping increases the absorption, crystallinity and electron mobility of TiO2 nanorods. The Bi-doped TiO2 has higher Jsc as compared with B-doped TiO2, mainly due to the improvement of electron density and increased absorption of TiO2 nanorods. The devices were fabricated from TiO2 nanorods being surface modified by organic dye W-4. The dye facilitates the bandgap alignment and compatibility between TiO2 and P3HT. The power conversion efficiency of solar cell has been increased by 1.33 times and 1.30 times for Bi-doped TiO2 and B-doped TiO2, respectively, as compared with that of as-synthesized TiO2. The results suggest the optical and electronic properties of TiO2 can be tuned by various dopants to enhance the device performance. PMID:25746184

Tu, Yu-Chieh; Lim, Herman; Chang, Chun-Yu; Shyue, Jing-Jong; Su, Wei-Fang

2015-06-15

64

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

E-print Network

1 Rectangular Bunched Rutile TiO2 Nanorod Arrays Grown on Carbon 2 Fiber for Dye-Sensitized Solar desirable for this 44 technology. 45 Here we introduce a fiber-shaped solar cell based on carbon 46 fibers a study of rectangular bunched 13 TiO2 nanorod (NR) arrays grown on carbon fibers (CFs) 14 from titanium

Wang, Zhong L.

65

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

Microsoft Academic Search

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)

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

2006-01-01

66

Effect of Photoelectrode with Phosphor-Containing TiO2 Layer for Dye-Sensitized Solar Cells  

NASA Astrophysics Data System (ADS)

Dye-sensitized solar cells (DSSCs) are composed of a dye-adsorbed nanoporous TiO2 layer on a fluorine-doped tin oxide (FTO) glass substrate, redox electrolytes, and a counter electrode. The phosphor is introduced into the TiO2 layer electrode in a DSSC. The content of phosphor-containing in the TiO2 paste is varied from 0.25 to 5.00 wt %. The synthesized TiO2 paste is deposited on FTO glass using a doctor blade. The conversion luminescence process of phosphor, increases both the light harvesting efficiency and the photocurrent. Using the 0.5 wt % Ba3Si6O12N2:Eu2+-containing TiO2 electrode, the light-to-electric-energy conversion efficiency of the DSSCs reaches 4.61% under simulated solar light irradiation at 100 mW/cm-2, which is an increase by a factor of 1.41 compared with that of the DSSCs without Ba3Si6O12N2:Eu2+.

Shin, Seong Gwan; Kim, Kyung Hwan; Wung Bark, Chung; Choi, Hyung Wook

2013-11-01

67

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

PubMed Central

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

2013-01-01

68

Low temperature (150 °C) fabrication of high-performance TiO2 films for dye-sensitized solar cells using ultraviolet light and plasma treatments of TiO2 paste containing organic binder  

NASA Astrophysics Data System (ADS)

Dye-sensitized solar cells (DSSCs) require annealing of TiO2 photoelectrodes at 450 °C to 550 °C. However, such high-temperature annealing is unfavorable because it limits the use of materials that cannot withstand high temperatures, such as plastic substrates. In our previous paper, a low-temperature annealing technique of TiO2 photoelectrodes using ultraviolet light and dielectric barrier discharge treatments was proposed to reduce the annealing temperature from 450 °C to 150 °C for a TiO2 paste containing an organic binder. Here, we measure the electron diffusion length in the TiO2 film, the amount of dye adsorption on the TiO2 film, and the sheet resistance of a glass substrate of samples manufactured with the 150 °C annealing method, and we discuss the effect that the 150 °C annealing method has on those properties of DSSCs.

Zen, Shungo; Inoue, Yuki; Ono, Ryo

2015-03-01

69

Effect of the LHCII pigment-protein complex aggregation on photovoltaic properties of sensitized TiO2 solar cells.  

PubMed

A modified dye-sensitized solar cell consisting of a thin TiO2 barrier layer sensitized with natural trimeric light-harvesting complex II (LHCII) from spinach was used as a biomimetic model to study the effects of LHCII aggregation on the photovoltaic properties. The aggregation of individual trimers induced molecular reorganization, which dramatically increased the photocurrent. The morphology of small- and large-size LHCII aggregates deposited on a surface was confirmed by atomic force microscopy. Enhanced LHCII immobilization was accomplished via electrostatic interaction with amine-functionalized photoanodes. The photocurrent responses of the assembled solar cells under illumination at three characteristic wavelength bands in the UV-Vis absorption spectra of LHCII solutions confirmed that a significant photocurrent was generated by LHCII photosensitizers. The enhanced photocurrent by large aggregated LHCII is shown to correlate with the quenching in the far-red fluorescence deriving from chlorophyll-chlorophyll charge transfer states that are effectively coupled with the TiO2 surface and thus inject electrons into the TiO2 conduction band. The large aggregated LHCII with more chlorophyll-chlorophyll charge transfer states is a much better sensitizer since it injects electrons more efficiently into the conduction band of TiO2 than the small aggregated LHCII mostly consisting of unquenched chlorophyll excited state. The assembled solar cells demonstrated remarkable stability in both aqueous buffer and acetonitrile electrolytes over 30 days. PMID:25168759

Yang, Yiqun; Jankowiak, Ryszard; Lin, Chen; Pawlak, Krzysztof; Reus, Michael; Holzwarth, Alfred R; Li, Jun

2014-10-14

70

CdS/CdSe cosensitized oriented single-crystalline TiO2 nanowire array for solar cell application  

NASA Astrophysics Data System (ADS)

Vertically oriented single-crystalline TiO2 nanowires array was grown on transparent conductive oxide glass substrate, and then CdS and CdSe quantum dots (QDs) were deposited on nanowires to form a TiO2/CdS/CdSe core-shell structure films. The optical properties of films with different layers of QDs were compared. The QD sensitized solar cells (QD-SSCs) were assembled and the effect of coating cycles of QDs on the photovoltaic performance was investigated. Under optimum parameters, QD-SSCs assembled with 5 ?m thick TiO2 nanowires film exhibited a short-circuit current density of 7.92 mA cm-2, an open-circuit voltage of 0.40 V, and a power conversion efficiency of 1.14%.

Li, Ming; Liu, Yong; Wang, Hai; Shen, Hui; Zhao, Wenxia; Huang, Hong; Liang, Chaolun

2010-11-01

71

NiO-decorated mesoporous TiO2 flowers for an improved photovoltaic dye sensitized solar cell.  

PubMed

Reducing light-induced e-h recombination is important for a dye sensitized solar cell (DSSC); the p-type NiO component in TiO2-NiO nanoparticles was reported to significantly decrease charge recombination, but its photovoltaic efficiency remains below 4% owing to a small surface area. In this work, we used a one-pot self-assembly process to fabricate flower-like mesoporous TiO2 decorated by NiO oxides, employing a pluronic polymer P123 as a structure directing and pore forming agent. The flower-like porous TiO2-NiO nanoparticles (F-TiO2-NiO NPs), possessing a high BET surface of 130 m(2) g(-1), are first used as a photoanode in DSSCs. These hybrid nanoparticles, decorated with NiO islands, are beneficial for improving photocurrent by increasing dye absorption and suppressing electron-hole recombination. The optimized F-TiO2-NiO NP anode (10 ?m thick) achieved a power conversion efficiency of 8.20%, which is 26% and 47% higher than pristine flower-like TiO2 and commercially available P25 anodes, respectively. This efficiency is the highest among the reported TiO2-NiO hybrid anodes. PMID:25600889

Zhi, Jian; Chen, Angran; Cui, Houlei; Xie, Yian; Huang, Fuqiang

2015-02-21

72

Hierarchically structured microspheres for high-efficiency rutile TiO(2)-based dye-sensitized solar cells.  

PubMed

Peachlike rutile TiO2 microsphere films were successfully produced on transparent conducting fluorine-doped tin oxide substrate via a facile, one-pot chemical bath route at low temperature (T = 80-85 °C) by introducing polyethylene glycol (PEG) as steric dispersant. The formation of TiO2 microspheres composed of nanoneedles was attributed to the acidic medium for the growth of 1D needle-shaped building blocks where the steric interaction of PEG reduced the aggregation of TiO2 nanoneedles and the Ostwald ripening process. Dye-sensitized solar cells (DSSCs) assembled by employing these complex rutile TiO2 microspheres as photoanodes exhibited a light-to-electricity conversion efficiency of 2.55%. It was further improved to a considerably high efficiency of 5.25% upon a series of post-treatments (i.e., calcination, TiCl4 treatment, and O2 plasma exposure) as a direct consequence of the well-crystallized TiO2 for fast electron transport, the enhanced capacity of dye loading, the effective light scattering, and trapping from microstructures. PMID:24467178

Ye, Meidan; Zheng, Dajiang; Wang, Mengye; Chen, Chang; Liao, Wenming; Lin, Changjian; Lin, Zhiqun

2014-02-26

73

Influence of the size-controlled TiO 2 nanotubes fabricated by low-temperature chemical synthesis on the dye-sensitized solar cell properties  

Microsoft Academic Search

Titanium dioxide nanotubes (TiO2 NTs) with various sizes have been prepared by low-temperature chemical synthesis using commercial anatase TiO2 particles with different crystallite size in NaOH solution and used as a photoelectrode in a dye-sensitized solar cell (DSSC).\\u000a The relationship between the physicochemical properties of electrode materials and photovoltaic performance was investigated.\\u000a The electrodes made from modified TiO2 NTs showed

Jang-Yul Kim; Tohru Sekino; Shun-Ichiro Tanaka

2011-01-01

74

Preparation of ZnO-coated TiO 2 electrodes using dip coating and their applications in dye-sensitized solar cells  

Microsoft Academic Search

This study investigates the applicability of a ZnO-coated TiO2 working electrode in a dye-sensitized solar cell (DSSC). This working electrode was designed and fabricated by the following procedures: (1) two consecutive TiCl4 treatments were performed when preparing the TiO2 electrode, one prior to and the other following the spin printing of the TiO2 colloid on a FTO-glass (Fluorine doped tin

Chuen-Shii Chou; Feng-Cheng Chou; Jhe-Yuan Kang

75

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

NASA Astrophysics Data System (ADS)

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

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

2011-07-01

76

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

77

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

78

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

PubMed Central

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

2013-01-01

79

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

PubMed

Poor dye loading on rutile TiO2 is one of the chief reasons for lower solar-to-electric conversion efficiency (?) in dye-sensitized solar cells (DSCs), compared to their anatase based counterparts. Previously, we showed that similar light harvesting for both rutile and anatase was realized by using a metal-free organic indoline dye, D149 [Sci. Rep., 2014, 4, 5769]. This was in contrast to the bulk of previous studies, which employed ruthenium based N719, leading to significant differences in light harvesting. To date, there has been no report directly comparing N719 and D149 for rutile based DSCs. In this work, three-dimensional hierarchical rutile TiO2 architecture (HRTA), consisting of one-dimensional nanorods, was successfully prepared via a facile hydrothermal method, and subsequently optimized as effective photoelectrodes for DSCs. Two dyes, N719 and D149, were used as sensitizers of the HRTA-based DSCs, with maximum ? of 5.6% and 5.8% achieved, respectively. The higher ? of the D149-sensitized DSC is ascribed to its higher extinction co-efficient, allowing a greater amount of light to be harvested with a thinner TiO2 layer. This study suggests that some of the limitations typically observed for rutile TiO2 based DSCs can be overcome through the use of strongly absorbing metal-free organic sensitizers. Furthermore, it reemphasises the importance of viewing DSCs as whole systems, rather than individual components. PMID:25690882

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

2015-03-01

80

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

NASA Astrophysics Data System (ADS)

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

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

2013-11-01

81

Performance enhancement of TiO2-based dye-sensitized solar cells by carbon nanospheres in photoanode  

E-print Network

The conversion efficiency of dye-sensitized solar cells (DSSCs) is optimized by modifying the optical design and improving absorbance within the cell. These objectives are obtained by creating different sized cavities in TiO2 photoanode. For this purpose, carbon nanospheres with diameters 100-600 nm are synthesized by hydrothermal method. A paste of TiO2 is mixed with various amounts of carbon nanospheres. During TiO2 photoanode sintering processes at 500C temperature, the carbon nanospheres are removed. This leads to random creation of cavities in the DSSCs photoanode. These cavities enhance light scattering and porosity which improve light absorbance by dye N719 and provide a larger surface area for dye loading. These consequences enhance performance of DSSCs. By mixing 3% Wt. carbon nanospheres in the TiO2 pastes, we were able to increase the short circuit current density and efficiency by 40% (from 12.59 to 17.73 mA/cm2) and 33% (from 5.72% to 7.59%), respectively.

Bayatloo, Elham; Polkoo, Sajad Saghaye

2013-01-01

82

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

PubMed

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

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

2012-04-01

83

A facile low temperature synthesis of TiO2 nanorods for high efficiency dye sensitized solar cells  

NASA Astrophysics Data System (ADS)

Titania (TiO2) nanorods have been synthesized with controlled size for dye-sensitized solar cells (DSSCs) via hydrothermal route at low hydrothermal temperature of 100 °C for 24 h. The titania nanorods were characterized using XRD, SEM, TEM/HRTEM, UV-vis Spectroscopy, FTIR and BET specific surface area ( S BET), as well as pore-size distribution by BJH. The results indicated that the bulk traps and the surface states within the TiO2 nanorods films have enhanced the efficiency of DSSCs. The size of the titania nanorods was 6.7 nm in width and 22 nm in length. The high surface area can provide more sites for dye adsorption, while the fast photoelectron-transfer channel can enhance the photogenerated electron transfer to complete the circuit. The specific surface area S BET was 77.14 m2 g-1 at the synthesis conditions. However, the band gap energy of the obtained titania nanorods was 3.2 eV. The oriented nanorods with appropriate lengths are beneficial in improving the electron transport property and thus leading to the increase of photocurrent, together enhancing the power conversion efficiency. A nearly quantitative absorbed photon-to-electrical current conversion achieved upon excitation at wave length of 550 nm and the power efficiency was enhanced from 5.6 % for commercial TiO2 nanoparticles Degussa (P25) cells to 7.2 % for TiO2 nanorods cells under AM 1.5 illumination (100 mW cm-2). The TiO2 cells performance was improved due to their high surface area, hierarchically mesoporous structures and fast electron-transfer rate compared with the Degussa (P25).

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

2013-01-01

84

TiO2 band shift by nitrogen-containing heterocycles in dye-sensitized solar cells: a periodic density functional theory study.  

PubMed

A density functional theory (DFT) method (periodic DMol3) with full geometry optimization was used to study the adsorption of nitrogen-containing heterocycles such as pyrazole, imidazole, 1,2,4-triazole, pyridine, pyrimidine, pyrazine, and 4-t-butylpyridine (TBP) on TiO2 anatase (101), (100), and (001) surfaces. All structures displayed a negative shift in the TiO2 Fermi level upon adsorption of N-containing heterocycles. Additionally, the heterocycles were examined as an additive in an I-/I3- redox electrolyte solution of dye-sensitized TiO2 solar cell. The DFT results indicated that the negative shift of TiO2 Fermi level was due to the adsorbate dipole moment component normal to the TiO2 surface plane, and corresponded to the enhanced open-circuit photovoltage (Voc) and the reduced short-circuit photocurrent density (Jsc) in a dye-sensitized solar cell. PMID:18331067

Kusama, Hitoshi; Orita, Hideo; Sugihara, Hideki

2008-04-15

85

ZnO nanosheets decorated with CdSe and TiO2 for the architecture of dye-sensitized solar cells.  

PubMed

Pure and TiO2- and CdSe-deposited ZnO nanosheets aligned vertically to the surface of ITO (Indium tin oxide) are prepared using electrodeposition, which is used for building blocks of dye sensitized solar cell. A significant improvement in the photovoltaic efficiency can be obtained by depositing TiO2 or CdSe on ZnO. Photoluminescence spectra show that the TiO2 and CdSe nanostructures suppress the recombination of the electron-hole pair of ZnO. We suggest that the interface charge transfer at TiO2-ZnO and CdSe-ZnO should be responsible for the suppression of the electron-hole pair recombination and enhanced solar cell efficiency by TiO2 and CdSe nanostructures. PMID:21449378

Kim, Young Tae; Park, Mi Yeong; Choi, Kang Ho; Tai, Wei Sheng; Shim, Won Hyun; Park, Sun-Young; Kang, Jae-Wook; Lee, Kyu Hwan; Jeong, Yongsoo; Kim, Young Dok; Lim, Dong Chan

2011-03-01

86

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

NASA Astrophysics Data System (ADS)

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

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

2015-02-01

87

Performance and stability studies of inverted polymer solar cells with TiO2 film as a buffer layer  

NASA Astrophysics Data System (ADS)

TiO2 based inverted polymer solar cells (PSCs) with a structure of fluorine-doped tin oxide (FTO)/TiO2/P3HT:PCBM/PEDOT:PSS/Ag presented excellent air stabilities,; the power conversion efficiency (PCE) of devices exhibited only 15 % decay as compared to the highest value while being exposed in air-condition for more than 20 days. Interestingly, an overall enhancement of PCE from 3.5 % to 3.9 % was observed while the PSCs were exposed in air-condition up to 3 days; the improvement of performance was attributed to the TiO2 films' oxygen and water protection effect and the oxidation of Ag, which will benefit to form an effective work function match with the HOMO of P3HT leading to improved ohmic contact. However, the performance slowly decreased when the exposure time remains longer due to the physical adsorbed oxygen. UV-ozone treatment on the TiO2 films' leads to the formation of a metal-deficient oxide that results in a decreased PCE for the devices. Finally, X-ray photo-emission spectroscopy (XPS) was used to analyze the compositional changes of the TiO2 films while they were exposed in air-condition or treated by UV-ozone.

Peng, Ruixiang; Yang, Feng; Ouyang, Xinhua; Liu, Ying; Kim, Yong-Sang; Ge, Ziyi

2014-02-01

88

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

89

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

90

Oligothiophene interlayer effect on photocurrent generation for hybrid TiO(2)/P3HT solar cells.  

PubMed

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

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

2014-10-01

91

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

PubMed Central

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

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

2014-01-01

92

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

NASA Astrophysics Data System (ADS)

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

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

2014-07-01

93

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

NASA Astrophysics Data System (ADS)

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

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

2015-02-01

94

Design of a TiO2 nanosheet/nanoparticle gradient film photoanode and its improved performance for dye-sensitized solar cells  

NASA Astrophysics Data System (ADS)

A TiO2 film photoanode with gradient structure in nanosheet/nanoparticle concentration on the fluorine-doped tin oxide glass from substrate to surface was prepared by a screen printing method. The as-prepared dye-sensitized solar cell (DSSC) based on the gradient film electrode exhibited an enhanced photoelectric conversion efficiency of 6.48%, exceeding that of a pure nanoparticle-based DSSC with the same film thickness by a factor of 2.6. The enhanced photovoltaic performance of the gradient film-based DSSC was attributed to the superior light scattering ability of TiO2 nanosheets within the gradient structure, which was beneficial to light harvesting. Furthermore, the TiO2 nanosheets with exposed {001} facets facilitated the electron transport from dye molecules to the conduction band of TiO2 and further to the conductive glass. Meanwhile, the high specific surface area of TiO2 nanosheets helped the adsorption of dye molecules, and the TiO2 nanoparticle underlayer ensured good electronic contact between the TiO2 film and the fluorine-doped tin oxide glass substrate. The electrochemical impedance spectroscopy measurements further confirmed the electron transport differences between DSSCs based on nanosheet/nanoparticle gradient film electrodes and DSSCs based on nanosheet/nanoparticle homogeneous mixtures, pure TiO2 nanoparticles and pure TiO2 nanosheets with the same film thickness.

Wang, Wenguang; Zhang, Haiyan; Wang, Rong; Feng, Ming; Chen, Yiming

2014-01-01

95

Design of a TiO2 nanosheet/nanoparticle gradient film photoanode and its improved performance for dye-sensitized solar cells.  

PubMed

A TiO2 film photoanode with gradient structure in nanosheet/nanoparticle concentration on the fluorine-doped tin oxide glass from substrate to surface was prepared by a screen printing method. The as-prepared dye-sensitized solar cell (DSSC) based on the gradient film electrode exhibited an enhanced photoelectric conversion efficiency of 6.48%, exceeding that of a pure nanoparticle-based DSSC with the same film thickness by a factor of 2.6. The enhanced photovoltaic performance of the gradient film-based DSSC was attributed to the superior light scattering ability of TiO2 nanosheets within the gradient structure, which was beneficial to light harvesting. Furthermore, the TiO2 nanosheets with exposed {001} facets facilitated the electron transport from dye molecules to the conduction band of TiO2 and further to the conductive glass. Meanwhile, the high specific surface area of TiO2 nanosheets helped the adsorption of dye molecules, and the TiO2 nanoparticle underlayer ensured good electronic contact between the TiO2 film and the fluorine-doped tin oxide glass substrate. The electrochemical impedance spectroscopy measurements further confirmed the electron transport differences between DSSCs based on nanosheet/nanoparticle gradient film electrodes and DSSCs based on nanosheet/nanoparticle homogeneous mixtures, pure TiO2 nanoparticles and pure TiO2 nanosheets with the same film thickness. PMID:24435106

Wang, Wenguang; Zhang, Haiyan; Wang, Rong; Feng, Ming; Chen, Yiming

2014-02-21

96

High efficiency solar cells as fabricated by Sb2S3-modified TiO2 nanofibrous networks.  

PubMed

High-efficiency hybrid solar cells (HSCs) based on electrospun titanium dioxide (TiO2) nanofibers plus poly(3-hexylthiophene) (P3HT) are fabricated by means of both the pretreatment using tetrahydrofuran (THF) vapor and the surface modification using n-type antimony chalcogenide (Sb2S3) on the TiO2 nanofibrous networks. It is revealed that the THF pretreatment not only reinforces the interfacial physical contact but also suppresses the interfacial recombination. The Sb2S3 modification improves the light absorption and charge transfer. Given that the active layer of the HSCs is as thin as 300 nm, it is demonstrated that the power conversion efficiency (PCE) is enhanced over 175%, exhibiting a PCE of 2.32%. PMID:23944152

Zhong, Jian; Zhang, Xiaojian; Zheng, Yongjia; Zheng, Man; Wen, Mingju; Wu, Sujuan; Gao, Jinwei; Gao, Xingsen; Liu, Jun-Ming; Zhao, Hongbo

2013-09-11

97

Microwave assisted chemical bath deposition of CdS on TiO 2 film for quantum dot-sensitized solar cells  

Microsoft Academic Search

A simple, rapid and effective method of microwave assisted chemical bath deposition (MACBD) has been used to deposit CdS quantum dots on the surface of TiO2 film as photoanode of quantum dot-sensitized solar cells. The photovoltaic performance of the as-prepared cell is investigated. The results show that the cell based on MACBD deposited TiO2\\/CdS electrode achieves an improved short circuit

Guang Zhu; Likun Pan; Tao Xu; Zhuo Sun

2011-01-01

98

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

PubMed Central

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

2013-01-01

99

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

E-print Network

Hierarchically Structured Microspheres for High-Efficiency Rutile TiO2Based Dye-Sensitized Solar Information ABSTRACT: Peachlike rutile TiO2 microsphere films were successfully produced on transparent microspheres composed of nanoneedles was attributed to the acidic medium for the growth of 1D needle

Lin, Zhiqun

100

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

NASA Astrophysics Data System (ADS)

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

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

2010-05-01

101

Effects of anodization growth of TiO2-nanotube array membrane on photo-conversion efficiency of dye-sensitized solar cell  

NASA Astrophysics Data System (ADS)

Membranes of TiO2 nanotube(NT) arrays were grown by potentiostatic anodic oxidation in an ethylene glycol electrolyte with small addition of H2O and NH4F. Ti metal plate with a thickness of 0.1 mm was completely converted into ?0.2 mm-thick TiO2 NT membrane for 24 to 96 h of anodization. Stacked NTs in membrane were separated into individual NT from the neighboring NTs as anodization continues up to 96 h. As-fabricated membrane of NTs were mechanically grinded to yield fine NT particles for the photoanode application to dye-sensitized solar cells (DSCs), in replacement of conventional TiO2 particles. Photo-conversion efficiency of the DSC using TiO2 crystalline NT particles is varying from 2.22% to 5.03%. Fine TiO2 NT particles can increase dye attachment due to high surface to volume ratio.

Park, Min-Woo; Chun, Ki-Young

2009-03-01

102

Liquid phase deposition of TiO2 nanolayer affords CH3NH3PbI3/nanocarbon solar cells with high open-circuit voltage.  

PubMed

Hybrid organic/inorganic perovskite solar cells are attracting intense attention and further developments largely hinge on understanding the fundamental issues involved in the cell operation. In this paper, a liquid phase deposition (LPD) method is developed to design and grow a TiO2 nanolayer at room temperature for carbon-based perovskite solar cells. The TiO2 nanolayer grown on FTO glass is compact but polycrystalline consisting of tiny anatase TiO2 nanocrystals intimately stacked together. By directly exploiting this TiO2 nanolayer in a solar cell of TiO2 nanolayer/CH3NH3PbI3/nanocarbon, we have achieved a Voc as high as 1.07 V, the highest value reported so far for hole transporter-free CH3NH3PbI3 solar cells. This is rationalized by the slower electron injection and longer electron lifetime due to the TiO2 nanolayer, which enhances the electron accumulation in CH3NH3PbI3 and consequently the Voc. By employing a rutile TiO2 nanorod (NR) array as a base structure for the LPD-TiO2 nanolayer to support the CH3NH3PbI3 layer, the photocurrent density is considerably increased without obviously compromising the Voc (1.01 V). As a result, the power conversion efficiency is boosted from 3.67% to 8.61%. More elaborate engineering of the TiO2 nanolayer by LPD in conjunction with judicious interfacing with other components has the potential to achieve higher performances for this type of solar cell. PMID:25406400

Chen, Haining; Wei, Zhanhua; Yan, Keyou; Yi, Ya; Wang, Jiannong; Yang, Shihe

2015-01-01

103

The effects of hydrothermal temperature and thickness of TiO 2 film on the performance of a dye-sensitized solar cell  

Microsoft Academic Search

The effects of hydrothermal temperature on the preparation of TiO2 colloids, and their film thickness on fluorine-doped tin oxide (FTO) glass, toward the performance of a dye-sensitized solar cell (DSSC) were investigated. Pore diameter and surface area of the TiO2 are of paramount importance in determining the cell efficiency. With the increase of hydrothermal temperature, the pore diameter increases linearly;

Chung-Yi Huang; Ying-Chan Hsu; Jian-Ging Chen; Vembu Suryanarayanan; Kun-Mu Lee; Kuo-Chuan Ho

2006-01-01

104

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

PubMed

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

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

2012-02-21

105

Dye-sensitized solar cells based on TiO 2 nanotubes and a solid-state electrolyte  

Microsoft Academic Search

Anatase TiO2 nanotubes were employed with success as photoanode in dye-sensitized solar cells (DSSC) using a plasticized polymer electrolyte based on a poly(ethylene oxide) derivative. The plasticized electrolyte, poly(ethylene oxide-co-epychlorohydrin) containing NaI–I2 had their conductivity and thermal behavior characterized as a function of the salt content. The highest ionic conductivity (5.5×10?4Scm?1) was obtained with 12.5wt% NaI and 50wt% of the

Ismael C. Flores; Jilian Nei de Freitas; Claudia Longo; Marco-Aurelio De Paoli; Herbert Winnischofer; Ana Flávia Nogueira

2007-01-01

106

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

107

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

Microsoft Academic Search

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

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

2011-01-01

108

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

109

An efficient and low-cost TiO 2 compact layer for performance improvement of dye-sensitized solar cells  

Microsoft Academic Search

A TiO2 organic sol was synthesised for the preparation of a compact TiO2 layer on fluorine-doped tin oxide (FTO) glass by a dip-coating technique. The resultant thin film was used for the fabrication of dye-sensitized solar cells (DSSCs). The compact layer typically has a thickness of ca. 110nm as indicated by its SEM, and consists of anatase as confirmed by

Hua Yu; Shanqing Zhang; Huijun Zhao; Geoffrey Will; Porun Liu

2009-01-01

110

Surface treatment of TiO 2 films for dye-sensitized solar cells using atmospheric-pressure non-equilibrium DC pulse discharge plasma jet  

Microsoft Academic Search

In this paper, we report the utilization of the DC pulse discharge plasma jet technique as a means for the preparation of titanium oxide (TiO2) films on fluorine dope tin oxide (FTO) coated glass substrates used for dye-sensitized solar cells (DSCs). The TiO2 film made on these experimental bases exhibited the BET specific surface area of 95m2\\/g, the pore volume

T. Yuji; H. Akatsuka; N. Mungkung; B. W. Park; Y. M. Sung

2008-01-01

111

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

112

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

2010-09-01

113

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. PMID:23704956

Andrei, Codrin; Zerulla, Dominic

2013-01-01

114

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

115

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

PubMed

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

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

2013-03-01

116

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

117

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

NASA Astrophysics Data System (ADS)

A type of highly efficient completely flexible fiber-shaped solar cell based on TiO2 nanotube array is successfully prepared. Under air mass 1.5G (100 mW cm-2) illumination conditions, the photoelectric conversion efficiency of the solar cell approaches 7%, the highest among all fiber-shaped cells based on TiO2 nanotube arrays and the first completely flexible fiber-shaped DSSC. The fiber-shaped solar cell demonstrates good flexibility, which makes it suitable for modularization using weaving technologies.A type of highly efficient completely flexible fiber-shaped solar cell based on TiO2 nanotube array is successfully prepared. Under air mass 1.5G (100 mW cm-2) illumination conditions, the photoelectric conversion efficiency of the solar cell approaches 7%, the highest among all fiber-shaped cells based on TiO2 nanotube arrays and the first completely flexible fiber-shaped DSSC. The fiber-shaped solar cell demonstrates good flexibility, which makes it suitable for modularization using weaving technologies. Electronic supplementary information (ESI) available. See DOI: 10.1039/c2nr11532h

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

2012-02-01

118

Sol-gel-Derived nano-sized double layer anti-reflection coatings (SiO2/TiO2) for low-cost solar cell fabrication.  

PubMed

We investigate nano-sized double layer anti-reflection coatings (ARCs) using a TiO2 and SiO2 sol-gel solution process for mono-crystalline silicon solar cells. The process can be easily adapted for spraying sol-gel coatings to reduce manufacturing cost. The spray-coated SiO2/TiO2 nano-sized double layer ARCs were deposited on mono-crystalline silicon solar cells, and they showed good optical properties. The spray coating process is a lower-cost fabrication process for large-scale coating than vacuum deposition processes such as PECVD. The measured average optical reflectance (300-1200 nm) was about approximately 8% for SiO2/TiO2 nano-sized double layer ARCs. The electrical parameters of a mono-crystalline silicon solar cell and reflection losses show that the SiO2/TiO2 stacks can improve cell efficiency by 0.2% compared to a non-coated mono-crystalline silicon solar cell. In the results, good correlation between theoretical and experimental data was obtained. We expect that the sol-gel spray-coated mono-crystalline silicon solar cells have high potential for low-cost solar cell fabrication. PMID:24245311

Lee, Seung Jun; Hur, Man Gyu; Yoon, Dae Ho

2013-11-01

119

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

120

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

PubMed Central

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. PMID:23394609

2013-01-01

121

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

PubMed

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

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

2011-07-01

122

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

NASA Astrophysics Data System (ADS)

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

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

2011-07-01

123

Pure anatase TiO2 ``nanoglue'': An inorganic binding agent to improve nanoparticle interconnections in the low-temperature sintering of dye-sensitized solar cells  

NASA Astrophysics Data System (ADS)

An interparticle-binding agent, or "nanoglue," was prepared for the fabrication of well-interconnected TiO2 photoelectrodes in dye-sensitized solar cells (DSSCs) sintered at low temperature. This nanoglue consisted of pure anatase particles approximately 5 nm in diameter dispersed in alcoholic solvent. When mixed with TiO2 particles 21 nm in diameter, the nanoglue induced interparticle chemical bridging via the condensation of hydroxyl groups on surfaces of TiO2 particles. The efficiency of nanoglue-based DSSCs was improved by approximately 25% compared to non-nanoglue-based DSSCs. This improvement was mainly ascribed to enhanced interparticle connections due to the presence of the 5 nm TiO2 particles in nanoglue.

Li, Yuelong; Lee, Wonjoo; Lee, Doh-Kwon; Kim, Kyungkon; Park, Nam-Gyu; Ko, Min Jae

2011-03-01

124

Growth of free-standing TiO 2 nanorod arrays and its application in CdS quantum dots-sensitized solar cells  

NASA Astrophysics Data System (ADS)

We report the fabrication of free-standing single-crystalline rutile TiO2 nanorod arrays (TiO2 F-SC-NRAs) by a simple one-step hydrothermal method. And these TiO2 F-SC-NRAs can be easily transplanted onto arbitrary substrates without any destructions of the original structure. Using the TiO2 F-SC-NRAs transplanted onto F-doped tin oxide substrates (FTO substrates) as the photo-anode to assemble cadmium sulfide quantum dots sensitized solar cells (CdS-QDSSCs), a maximum power conversion efficiency of 1.27% under 1.5 AM (100 mW/cm2) illumination can be obtained in this work.

Zeng, Tao; Tao, Haizheng; Sui, Xiaotao; Zhou, Xuedong; Zhao, Xiujian

2011-05-01

125

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

126

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

2014-08-28

127

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

NASA Astrophysics Data System (ADS)

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

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

2014-11-01

128

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

PubMed

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

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

2012-07-01

129

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

NASA Astrophysics Data System (ADS)

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

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

2013-11-01

130

Three-Dimensional TiO2/ZnO Hybrid Array as a Heterostructured Anode for Efficient Quantum-Dot-Sensitized Solar Cells.  

PubMed

The development of a novel nanoarray photoanode with a heterostructure on a transparent conducting oxide substrate provides a promising scheme to fabricate efficient energy conversion devices. Herein, we successfully synthesize the vertically aligned hierarchical TiO2 nanowire/ZnO nanorod or TiO2 nanowire/ZnO nanosheet hybrid arrays, which are proven to be excellent anode candidates for superior light utilization. Consequently, the quantum-dot-sensitized solar cells based on such hybrid arrays exhibit an impressive power conversion efficiency (PCE) under AM 1.5G one sun illumination with improved short-circuit current density (JSC) and fill factor compared to pristine TiO2 nanowire arrays. Combined with the chemical-bath-deposited Cu2S counter electrode, the eventual PCE can be further optimized to as high as 4.57% for CdS/CdSe co-sensitized quantum dot solar cells. PMID:25679232

Feng, Hao-Lin; Wu, Wu-Qiang; Rao, Hua-Shang; Wan, Quan; Li, Long-Bin; Kuang, Dai-Bin; Su, Cheng-Yong

2015-03-11

131

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

PubMed Central

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

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

2014-01-01

132

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

PubMed Central

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

2013-01-01

133

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

NASA Astrophysics Data System (ADS)

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

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

2014-03-01

134

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

PubMed

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

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

2013-12-26

135

Photoanode based on chain-shaped anatase TiO2 nanorods for high-efficiency dye-sensitized solar cells.  

PubMed

Anatase TiO(2) nanorods with large specific surface areas and high crystallinity have been synthesized by surfactant-free hydrothermal treatment of water-soluble peroxotitanium acid (PTA). X-ray diffraction and TEM analysis showed that all TiO(2) nanorods derived from PTA in different hydrothermal processes were in the anatase phase, and high aspect ratio TiO(2) nanorods with chain-shaped structures were formed at 150?°C for 24?h by oriented growth. The nanorods were fabricated as photoanodes for high-efficiency dye-sensitized solar cells (DSSCs). DSSCs fabricated from the chain-shaped TiO(2) nanorods gave a highest short-circuit current density of 14.8?mA?cm(-2) and a maximum energy conversion efficiency of 7.28?%, as a result of the presence of far fewer surface defects and grain boundaries than are present in commercial P25 TiO(2) nanoparticles. Electrochemical impedance spectroscopy also confirmed that DSSCs based on the TiO(2) nanorods have enhanced electron transport properties and a long electron lifetime. PMID:22890917

Rui, Yichuan; Li, Yaogang; Wang, Hongzhi; Zhang, Qinghong

2012-10-01

136

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

PubMed

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

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

2015-02-01

137

Fabrication of Au@Ag core/shell nanoparticles decorated TiO2 hollow structure for efficient light-harvesting in dye-sensitized solar cells.  

PubMed

Improving the light-harvesting properties of photoanodes is promising way to enhance the power conversion efficiency (PCE) of dye-sensitized solar cells (DSSCs). We synthesized Au@Ag core/shell nanoparticles decorated TiO2 hollow nanoparticles (Au@Ag/TiO2 HNPs) via sol-gel reaction and chemical deposition. The Au@Ag/TiO2 HNPs exhibited multifunctions from Au@Ag core/shell NPs (Au@Ag CSNPs) and TiO2 hollow nanoparticles (TiO2 HNPs). These Au@Ag CSNPs exhibited strong and broadened localized surface plasmon resonance (LSPR), together with a large specific surface area of 129 m(2) g(-1), light scattering effect, and facile oxidation-reduction reaction of electrolyte from TiO2 HNPs, which resulted in enhancement of the light harvesting. The optimum PCE of ? = 9.7% was achieved for the DSSCs using photoanode materials based on TiO2 HNPs containing Au@Ag/TiO2 HNPs (0.2 wt % Au@Ag CSNPs with respect to TiO2 HNPs), which outperformed by 24% enhancement that of conventional photoanodes formed using P25 (? = 7.8%). PMID:25562329

Yun, Juyoung; Hwang, Sun Hye; Jang, Jyongsik

2015-01-28

138

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

PubMed

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

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

2013-01-01

139

Template-free TiO2 hollow submicrospheres embedded with SnO2 nanobeans as a versatile scattering layer for dye-sensitized solar cells.  

PubMed

Nanobean SnO2-embedded TiO2 hollow submicrospheres are presented as a scattering layer for the first time in dye-sensitized solar cells. This designed mesoporous submicrostructure simultaneously promotes dye adsorption, light harvesting, and electron transport, leading to 28% improvement in the conversion efficiency compared to film-based SnO2. PMID:25578042

Wang, Chih-Liang; Liao, Jin-Yun; Zhao, Yubao; Manthiram, Arumugam

2015-02-01

140

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

141

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

PubMed

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

Kiyonaga, Tomokazu; Akita, Tomoki; Tada, Hiroaki

2009-04-21

142

New development of nanocrystalline TiO2-based dye-sensitized solar cells  

Microsoft Academic Search

Techniques of dye-sensitized nanocrystalline solar cells(DSSCs) having a conversion efficiency of AM 1.5G solar light to electric power over 11% are reported. In this paper,the fundamental structure and the principle of DSSCs are introduced and the development of key components, including nanoporous semiconductor films, dye sensitizers, electrolyte and counter electrode in DSSCs are reviewed in detail. It is also an

Chao Song; Xiangting Dong; Jinxian Wang; Guixia Liu; Wensheng Yu

2009-01-01

143

Preparation of a nanoporous CaCO3-coated TiO2 electrode and its application to a dye-sensitized solar cell.  

PubMed

A nanoporous CaCO3 overlayer-coated TiO2 thick film was prepared by the topotactic thermal decomposition of Ca(OH)2, and its performance as an electrode of a dye-sensitized solar cell was investigated. As compared to bare TiO2, nanoporous CaCO3-coated TiO2 provided higher specific surface area and, subsequently, a larger amount of dye adsorption; this in turn increased short-circuit current (Jsc). Furthermore, the CaCO3 coating demonstrated increased impedance at the TiO2/dye/electrolyte interface and increased the lifetime of the photoelectrons, indicating the improved retardation of the back electron transfer, which increases Jsc, open-circuit voltage (Voc), and fill factor (ff). Thereby, the energy conversion efficiency (eta) of the solar cell improved from 7.8 to 9.7% (an improvement of 24.4%) as the nanoporous CaCO3 layer was coated onto TiO2 thick films. PMID:17927224

Lee, Sangwook; Kim, Jin Young; Youn, Sung Hun; Park, Min; Hong, Kug Sun; Jung, Hyun Suk; Lee, Jung-Kun; Shin, Hyunho

2007-11-01

144

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

145

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

146

TiO2 and pyrochlore Tm2Ti2O7 based semiconductor as a photoelectrode for dye-sensitized solar cells  

NASA Astrophysics Data System (ADS)

This study presents the use of TiO2 nanoparticles with Tm as photoelectrodes in DSSCs. The nanoparticles were annealed at 1173?K and the predominant TiO2 phase was rutile. XRD and Raman spectroscopy revealed the presence of a crystalline pyrochlore phase of the mixed oxide Tm2Ti2O7. In turn, XPS confirmed the presence of Ti4+ and Tm3+, so the inclusion of Tm did not affect the oxidation state of the Ti. UV–Vis spectra showed that the presence of the pyrochlore phase led to new electronic states in the band gap. The use of the pyrochlore phase in the photoelectrode had a positive effect, improving the efficiency of the pure TiO2 cells. The efficiency increased by between 2.32% and 3.16% when pure TiO2 was replaced with a mixture of rutile TiO2 and pyrochlore Tm2Ti2O7, so the controlled use of a pyrochlore phase can produce good results in dye-sensitized solar cells. Another important effect of the pyrochlore phase was to increase the open-circuit voltage values by around 7% and can be explained by the flat band voltage values. The samples with Tm showed two flat band voltage values, which generated two possible electronic injection mechanisms in the cells.

Aguilar, Teresa; Navas, Javier; De los Santos, Desireé M.; Sánchez-Coronilla, Antonio; Fernández-Lorenzo, Concha; Alcántara, Rodrigo; Gallardo, Juan Jesus; Blanco, Ginesa; Martín-Calleja, Joaquín

2015-04-01

147

Performance enhancement of perovskite solar cells with Mg-doped TiO2 compact film as the hole-blocking layer  

NASA Astrophysics Data System (ADS)

In this letter, we report perovskite solar cells with thin dense Mg-doped TiO2 as hole-blocking layers (HBLs), which outperform cells using TiO2 HBLs in several ways: higher open-circuit voltage (Voc) (1.08 V), power conversion efficiency (12.28%), short-circuit current, and fill factor. These properties improvements are attributed to the better properties of Mg-modulated TiO2 as compared to TiO2 such as better optical transmission properties, upshifted conduction band minimum (CBM) and downshifted valence band maximum (VBM), better hole-blocking effect, and higher electron life time. The higher-lying CBM due to the modulation with wider band gap MgO and the formation of magnesium oxide and magnesium hydroxides together resulted in an increment of Voc. In addition, the Mg-modulated TiO2 with lower VBM played a better role in the hole-blocking. The HBL with modulated band position provided better electron transport and hole blocking effects within the device.

Wang, Jing; Qin, Minchao; Tao, Hong; Ke, Weijun; Chen, Zhao; Wan, Jiawei; Qin, Pingli; Xiong, Liangbin; Lei, Hongwei; Yu, Huaqing; Fang, Guojia

2015-03-01

148

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

149

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

PubMed

We report on high-performance dye-sensitized solar cells (DSSCs) based on nitrogen doped anatase TiO2-CuxO core-shell mesoporous hybrids synthesized through a facile and controlled combined sol-gel and hydrothermal process in the presence of hexadecylamine as the structure-directing agent. The matching of band edges between CuxO and TiO2 to form a semiconductor heterojunction plays an important role in effective separation of light induced electrons and holes, providing a promising photoanode for DSSCs because of its wide absorption spectrum, high electron injection efficiency, and fast electron transference. DSSCs based on the mesoporous TiO2-CuxO core-shell hybrids show a high short-circuit current density of 9.60 mA cm(-2) and a conversion efficiency of 3.86% under one sun illumination. While DSSCs based on the N-doped mesoporous TiO2-CuxO hybrids exhibit the higher short-circuit current density of 13.24 mA cm(-2) and a conversion efficiency of 4.57% under one sun illumination. In comparison with un-doped TiO2-CuxO hybrids, the doping of nitrogen into the lattice of TiO2 can extend the light absorption in the ultraviolet range to the visible light region and effectively decrease the recombination rate of photo-generated electrons and holes. The presented N-doped mesoporous TiO2-CuxO hybrids as photoanodes could find potential applications for high performance DSSCs. PMID:25407021

Guo, Enyan; Yin, Longwei

2015-01-01

150

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

NASA Astrophysics Data System (ADS)

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

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

2015-01-01

151

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

PubMed

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

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

2008-01-15

152

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

153

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

PubMed

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

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

2014-12-19

154

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

155

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

PubMed

In this study, well-crystallized TiO2 nanoparticles with average size of -20 nm were synthesized by hydrolysis of titania salt in aqueous medium. The effect of the optical properties of the obtained titania particles based thin films with different thickness on the photovoltaic performance of dye-sensitized solar cells were investigated. Differential thermal analysis/thermo-gravimetric analysis, scanning electron microscopy, transmission electron microscopy and X-ray diffraction were used to characterize the morphology, structure and crystal formation of the obtained samples. The optical properties such as reflectance and transmittance of the photoanodes with different thickness were systematically investigated. The reflectance property increased with increasing the film thickness, however, the transmittance property showed the opposite way. The improved scattering property with increasing the film thickness facilitated efficient utilization of solar spectrum, which was verified by incident photon-to-current conversion efficiency. The maximum energy conversion efficiency of 5.0% was achieved on photoelectrode film with 17.8 microm. PMID:23862431

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

2013-06-01

156

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

PubMed Central

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

2013-01-01

157

Vertically aligned TiO2 nanotubes on plastic substrates for flexible solar cells.  

PubMed

Electrochemical anodization of a titanium film on a Kapton HN substrate leads to the formation of closely packed aligned nanotubes, whose shape can be finely tuned by tailoring the anodization parameters. An amorphous-to-anatase phase transition is induced on nanotubes by annealing at 350 °C. The nanotubes are applied as photoanodes in flexible dye-sensitized solar cells (N719 dye; I3-/I- redox couple), resulting in a photoconversion efficiency of up to 3.5% under simulated sunlight irradiation air mass 1.5 global (AM 1.5G). PMID:21793205

Galstyan, Vardan; Vomiero, Alberto; Concina, Isabella; Braga, Antonio; Brisotto, Mariangela; Bontempi, Elza; Faglia, Guido; Sberveglieri, Giorgio

2011-09-01

158

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

NASA Astrophysics Data System (ADS)

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

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

2014-08-01

159

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

160

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

PubMed

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

Lin, Jia; Chen, Jingfei; Chen, Xianfeng

2011-01-01

161

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

PubMed Central

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

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

2014-01-01

162

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

NASA Astrophysics Data System (ADS)

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

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

2014-02-01

163

Sb2S3 nanoparticles through solution chemistry on mesoporous TiO2 for solar cell application  

NASA Astrophysics Data System (ADS)

A facile room temperature (27 °C) chemical route, namely successive ionic layer adsorption and reaction (SILAR) method is used to deposit antimony trisulphide (Sb2S3) nanoparticles on mesoporous titanium dioxide (TiO2). The method facilitates linker free approach to deposit the size tuned nanoparticles. The synthesized TiO2/Sb2S3 structure on a FTO (fluorine doped tin oxide coated glass substrate) was used as a photoanode with polysulphide as liquid electrolyte and platinum coated FTO as back contact to construct the photovoltaic device. The photovoltaic performances have been tested under light illumination with standard solar simulator condition (AM 1.5G, 10 mW/cm2) and photovoltaic parameters are discussed.

Salunkhe, D. B.; Gargote, S. S.; Dubal, D. P.; Kim, W. B.; Sankapal, B. R.

2012-12-01

164

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

PubMed

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

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

2012-04-01

165

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

NASA Astrophysics Data System (ADS)

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

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

2014-12-01

166

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

Microsoft Academic Search

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

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

2010-01-01

167

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

Microsoft Academic Search

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

Radhakrishnan Sivakumar; Krishnasamy Akila; Sambandam Anandan

2010-01-01

168

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

Microsoft Academic Search

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

Jinsoo Kim; Jonghyun Kim; Myeongkyu Lee

2010-01-01

169

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

Microsoft Academic Search

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

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

2011-01-01

170

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

PubMed

The morphology of nano-titania has a significant effect on the photoelectric properties of dye-sensitized solar cells. In this study, microsphere assembly of a TiO2 mesoporous nanosheet constructed by nanocuboids was conducted via a simple hydrothermal process. The XRD pattern indicated that the hierarchical mesoporous microspheres are anatase phase with decreased (004) peaks. Raman spectrum shows enhanced Eg peaks at 143 and 638 cm(-1) caused by the symmetric stretching vibration of O-Ti-O of the (101) crystalline facet in anatase TiO2. FESEM and TEM images show that well monodispersed TiO2 microspheres with a diameter of 2 ?m are assembled by TiO2 mesoporous nanosheets with exposed (101) facets. The oriented attachment of TiO2 nanocuboids along the (101) direction leads to the formation of mesoporous titania nanosheets. The UV-Vis spectrum shows that the mesoporous TiO2 nanosheets have high scattering ability and light absorption by dye. Quasi-solid-state dye-sensitized solar cells that incorporate these microspheres into the top scattering layers exhibit a prominent improvement in the power conversion efficiency of 7.51%, which shows a 45.8% increase in the overall conversion efficiency when compared with the spine hierarchical TiO2 microspheres (5.15%). There is the potential application for microsphere assembly of mesoporous TiO2 nanosheets in quasi-solid-state dye-sensitized solar cells with excellent stability. PMID:25631573

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

2015-02-12

171

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

NASA Astrophysics Data System (ADS)

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

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

2012-01-01

172

Formation of efficient dye-sensitized solar cells by introducing an interfacial layer of long-range ordered mesoporous TiO2 thin film.  

PubMed

Long-range ordered cubic mesoporous TiO 2 films with 300 nm thickness were fabricated on fluorine-doped tin oxide (FTO) substrate by evaporation-induced self-assembly (EISA) process using F127 as a structure-directing agent. The prepared mesoporous TiO 2 film (Meso-TiO 2) was applied as an interfacial layer between the nanocrystalline TiO 2 film (NC-TiO 2) and the FTO electrode in the dye-sensitized solar cell (DSSC). The introduction of Meso-TiO 2 increased J sc from 12.3 to 14.5 mA/cm (2), and V oc by 55 mV, whereas there was no appreciable change in the fill factor (FF). As a result, the photovoltaic conversion efficiency ( eta) was improved by 30.0% from 5.77% to 7.48%. Notably, introduction of Meso-TiO 2 increased the transmittance of visible light through the FTO glass by 23% as a result of its excellent antireflective role. Thus the increased transmittance was a key factor in enhancing the photovoltaic conversion efficiency. In addition, the presence of interfacial Meso-TiO 2 provided excellent adhesion between the FTO and main TiO 2 layer, and suppressed the back-transport reaction by blocking direct contact between the electrolyte and FTO electrode. PMID:18922027

Kim, Yong Joo; Lee, Yoon Hee; Lee, Mi Hyeon; Kim, Hark Jin; Pan, Jia Hong; Lim, Goo Il; Choi, Young S; Kim, Kyungkon; Park, Nam-Gyu; Lee, Chongmu; Lee, Wan In

2008-11-18

173

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

PubMed

To investigate the microstructural effects of the synthesized TiO2 nanopowders such as particle size, specific surface area, pore size and pore distributions for the application of an anode material of dye-sensitized solar cells (DSSC), size-controlled and well-dispersed TiO2 nanopowders were synthesized by chemical vapor condensation (CVC) process in the range of 800-1000 degreesC under a pressure of 50 mbar. The average particle size of synthesized TiO2 nanopowders was increased with increasing temperature from 13 nm for 800 degreesC, 15 nm for 900 degreesC and 26 nm. The specific surface area of synthesized nanoparticles were measured as 119.1 m2/g for 800 degreesC, 104.7 m2/g for 900 degreesC and 59.5 m2/g for 1000 degreesC, respectively. The conversion efficiency values (eta%) of DSSC with the synthesized TiO2 nanopowders at 800 degreesC, 900 degreesC, and 1000 degreesC were 2.59%, 5.96% and 3.66%, respectively. The highest conversion efficiency obtained in the 900 degreesC (5.96%) sample is thought to be attributable to homogeneous particle size and pore distributions, large specific surface area, and high transmittance in regions of dye absorption wavelength. PMID:23901483

Kim, Woo-Byoung; Lee, Jai-Sung

2013-07-01

174

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

175

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

NASA Astrophysics Data System (ADS)

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

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

2015-01-01

176

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

NASA Astrophysics Data System (ADS)

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

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

2013-10-01

177

Roles of electrolytes on charge recombination in dye-sensitized TiO(2) solar cells (2): the case of solar cells using cobalt complex redox couples.  

PubMed

Dye-sensitized solar cells (DSC) were prepared from nanoporous TiO(2) electrodes with two different cobalt complex redox couples, propylene-1,2-bis(o-iminobenzylideneaminato)cobalt(II) {Co(II)(abpn)} and tris(4,4'-di-tert-buthyl-2,2'-bipyridine)cobalt(II) diperchlorate {Co(II)(dtb-bpy)(3)(ClO(4))(2)}. The performances of the DSCs were examined with varying the concentrations of the redox couples and Li cations in methoxyacetonitrile. Under 1 sun conditions, short-circuit currents (J(sc)) increased with the increase of the redox couple concentration, and the maximum J(sc) was found at the Li(+) concentration of 100 mM. To rationalize the observed trends of J(sc), electron diffusion coefficients and lifetimes in the DSCs were measured. Electron diffusion coefficients in the DSCs using cobalt complexes were comparable to the previously reported values of nanoporous TiO(2). Electron lifetime was independent of the concentration of the redox couples when the concentration ratio of Co(II)(L) and Co(III)(L) was fixed. With the increase of Li(+) concentration, the electron lifetime increased. These results were interpreted as due to their slow charge-transfer kinetics and the cationic nature of Co complex redox couples, in contrast to the anionic redox couple of I(-)/I(3)(-). The increase of the lifetimes with Li(+) was interpreted with the decrease of the local concentration of Co(III) near the surface of TiO(2). The addition of 4-tert-butylpyridine (tBP) with the presence of Li(+) increased J(sc) significantly. The observed increase of the electron lifetime by tBP could not explain the large increase of J(sc), implying that tBP facilitates the charge transfer from Co(II)(L) to dye cation, with the association of the change of the reorganization energy between Co(II) and Co(III). PMID:16851383

Nakade, Shogo; Makimoto, Yohei; Kubo, Wataru; Kitamura, Takayuki; Wada, Yuji; Yanagida, Shozo

2005-03-01

178

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

PubMed

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

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

2012-10-14

179

TiO2 nanocrystalline layer as a bridge linking TiO2 sub-microspheres layer and substrates for high-efficiency dye-sensitized solar cells  

NASA Astrophysics Data System (ADS)

TiO2 sub-microspheres possess high surface area and superior light scattering effect which contributes to the high photocurrent density (Jsc) and power conversion efficiency (?) of dye-sensitized solar cells (DSSCs). However, the poor interconnection between the TiO2 sub-microspheres with substrates (N0S4) restricts the electron transport and charge collection. In order to resolve this drawback, we adopted a nanocrystalline monolayer as bridges to contact between the sub-microspheres and substrates (N1S3). The improved contact provides more direct transport channels and increases the increased electron concentration gradient from the top electrode to the bottom electrode, which accelerates the electron transport and charge collection. The combined effects of the faster electron transport rate, less surface states and higher collection efficiency for the N1S3 based DSSC contribute to the higher Jsc and ? compared to the N0S4 based DSSC. While the photoelectrodes of N2S2 and N3S1 are too thick of nanocrystalline layer to improve the performance of DSSCs due to the decreased dye loading, reduced light scattering ability and increased crystal boundaries. As a result, a higher ? of 10.34% is achieved by introducing the nanocrystalline layer, whereas, only 9.17% is obtained for the photoelectrode without this bridge.

Ding, Yong; Mo, Li-E.; Tao, Li; Ma, Yan-Mei; Hu, Lin-Hua; Huang, Yang; Fang, Xia-Qin; Yao, Jian-Xi; Xi, Xiao-Wang; Dai, Song-Yuan

2014-12-01

180

Highly efficient quantum dot-sensitized TiO2 solar cells based on multilayered semiconductors (ZnSe/CdS/CdSe)  

NASA Astrophysics Data System (ADS)

A new approach by inserting a layer of ZnSe QDs was studied to enhance the adsorption of CdS/CdSe QDs resulting in much improved power conversion efficiency. ZnSe, CdS and CdSe QDs were sequentially assembled on a nanocrystalline TiO2 film to prepare a ZnSe/CdS/CdSe sensitized photoelectrode for QD-sensitized solar cell (QDSSC) applications. The results show that the performance of QDSSCs is strongly dependent on the order of the QDs with respect to TiO2. The pre-assembled ZnSe QD layer acts as a seed layer in the subsequent SILAR process, inducing both the nucleation and growth of CdS QDs, whereas CdS and CdSe QDs have a complementary effect in light harvesting. In the cascade structure of TiO2/ZnSe/CdS/CdSe electrode, a high efficiency of 4.94% and a long electron lifetime of 87.4 ms were achieved, which can be attributed to the following factors: the higher intensity and red shift of light absorption in 400-700 nm range increase the electron concentration in TiO2 substrate sensitized by ZnSe/CdS/CdSe compared to the others, which directly accelerate electron transport in TiO2 and their transfer to FTO glass; the re-organization of energy levels among ZnSe, CdS and CdSe forms a stepwise structure of band-edge levels, which is advantageous to the electron injection and hole recovery of QDs.A new approach by inserting a layer of ZnSe QDs was studied to enhance the adsorption of CdS/CdSe QDs resulting in much improved power conversion efficiency. ZnSe, CdS and CdSe QDs were sequentially assembled on a nanocrystalline TiO2 film to prepare a ZnSe/CdS/CdSe sensitized photoelectrode for QD-sensitized solar cell (QDSSC) applications. The results show that the performance of QDSSCs is strongly dependent on the order of the QDs with respect to TiO2. The pre-assembled ZnSe QD layer acts as a seed layer in the subsequent SILAR process, inducing both the nucleation and growth of CdS QDs, whereas CdS and CdSe QDs have a complementary effect in light harvesting. In the cascade structure of TiO2/ZnSe/CdS/CdSe electrode, a high efficiency of 4.94% and a long electron lifetime of 87.4 ms were achieved, which can be attributed to the following factors: the higher intensity and red shift of light absorption in 400-700 nm range increase the electron concentration in TiO2 substrate sensitized by ZnSe/CdS/CdSe compared to the others, which directly accelerate electron transport in TiO2 and their transfer to FTO glass; the re-organization of energy levels among ZnSe, CdS and CdSe forms a stepwise structure of band-edge levels, which is advantageous to the electron injection and hole recovery of QDs. Electronic supplementary information (ESI) available. See DOI: 10.1039/c4nr06935h

Yang, Lin; McCue, Connor; Zhang, Qifeng; Uchaker, Evan; Mai, Yaohua; Cao, Guozhong

2015-02-01

181

Highly efficient quantum dot-sensitized TiO2 solar cells based on multilayered semiconductors (ZnSe/CdS/CdSe).  

PubMed

A new approach by inserting a layer of ZnSe QDs was studied to enhance the adsorption of CdS/CdSe QDs resulting in much improved power conversion efficiency. ZnSe, CdS and CdSe QDs were sequentially assembled on a nanocrystalline TiO2 film to prepare a ZnSe/CdS/CdSe sensitized photoelectrode for QD-sensitized solar cell (QDSSC) applications. The results show that the performance of QDSSCs is strongly dependent on the order of the QDs with respect to TiO2. The pre-assembled ZnSe QD layer acts as a seed layer in the subsequent SILAR process, inducing both the nucleation and growth of CdS QDs, whereas CdS and CdSe QDs have a complementary effect in light harvesting. In the cascade structure of TiO2/ZnSe/CdS/CdSe electrode, a high efficiency of 4.94% and a long electron lifetime of 87.4 ms were achieved, which can be attributed to the following factors: the higher intensity and red shift of light absorption in 400-700 nm range increase the electron concentration in TiO2 substrate sensitized by ZnSe/CdS/CdSe compared to the others, which directly accelerate electron transport in TiO2 and their transfer to FTO glass; the re-organization of energy levels among ZnSe, CdS and CdSe forms a stepwise structure of band-edge levels, which is advantageous to the electron injection and hole recovery of QDs. PMID:25615827

Yang, Lin; McCue, Connor; Zhang, Qifeng; Uchaker, Evan; Mai, Yaohua; Cao, Guozhong

2015-02-21

182

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

PubMed

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

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

2012-10-01

183

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

NASA Astrophysics Data System (ADS)

We investigated CdSe-sensitized TiO2 solar cells by means of electrodeposition under galvanostatic control. The electrodeposition of CdSe within the mesoporous film of TiO2 gives rise to a uniform, thickness controlled, conformal layer of nanostructured CdSe particles intimately wrapping the anatase TiO2 nanoparticles. This technique has the advantage of providing not only a fast method for sensitization ( < 5 min) but also being easily scalable to the sensitization of large-area panels. XRD together with SAED analysis highlight that the deposit of CdSe is exclusively constituted of the hexagonal polymorph. In addition, hierarchical growth has also been shown, starting from the formation of a TiO2-CdSe core-shell structure followed by the growth of an assembly of CdSe nanoparticles resembling cauliflowers. This assembly exhibits at its core a mosaic texture with crystallites of about 3 nm in size, in contrast to a shell composed of well-crystallized single crystals between 5 and 10 nm in size. Preliminary results on the photovoltaic performance of such a nanostructured composite of TiO2 and CdSe show 0.8% power conversion efficiency under A.M.1.5 G conditions—100 mW cm-2 in association with a new regenerative redox couple based on cobalt(+III/+II) polypyridil complex (Voc = 485 mV, Jsc = 4.26 mA cm -2, ff=0.37).

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

2012-10-01

184

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

PubMed Central

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

2014-01-01

185

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

NASA Astrophysics Data System (ADS)

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

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

2014-01-01

186

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

187

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

NASA Astrophysics Data System (ADS)

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

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

2015-02-01

188

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

NASA Astrophysics Data System (ADS)

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.

Kim, Ji-Hong; Lee, Kyung-Ju; Roh, Ji-Hyung; Song, Sang-Woo; Park, Jae-Ho; Yer, In-Hyung; Moon, Byung-Moo

2012-01-01

189

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

190

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

191

Influence of the preparation conditions of TiO 2 electrodes on the performance of solid-state dye-sensitized solar cells with CuI as a hole collector  

Microsoft Academic Search

Solid-state dye-sensitized solar cells (DSSCs) were fabricated in which the thin p-CuI film acts as a hole collector. Influences of the different preparation methods, composition, aging time of the TiO2 pastes and sensitizing time on the performance of the cells were investigated. Different preparation routes for the TiO2 paste do not obviously affect the performance of the cells. The volume

Li Yang; Zhengxi Zhang; Shaohua Fang; Xuhui Gao; Masamichi Obata

2007-01-01

192

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

PubMed Central

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

2013-01-01

193

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

NASA Astrophysics Data System (ADS)

Inorganic/organic heterojunction solar cells (HSCs) have attracted increasing attention as a cost-effective alternative to conventional solar cells. This work presents an HSC by in situ growth of CuInS2 (CIS) layer as the photoabsorption material on nanoporous TiO2 film with the use of poly(3-hexylthiophene) (P3HT) as hole-transport material. The in situ growth of CIS nanocrystals has been realized by solvothermally treating nanoporous TiO2 film in ethanol solution containing InCl3 · 4H2O, CuSO4 · 5H2O, and thioacetamide with a constant concentration ratio of 1:1:2. InCl3 concentration plays a significant role in controlling the surface morphology of CIS layer. When InCl3 concentration is 0.1 M, there is a layer of CIS flower-shaped superstructures on TiO2 film, and CIS superstructures are in fact composed of ultrathin nanoplates as `petals' with plenty of nanopores. In addition, the nanopores of TiO2 film are filled by CIS nanocrystals, as confirmed using scanning electron microscopy image and by energy dispersive spectroscopy line scan analysis. Subsequently, HSC with a structure of FTO/TiO2/CIS/P3HT/PEDOT:PSS/Au has been fabricated, and it yields a power conversion efficiency of 1.4%. Further improvement of the efficiency can be expected by the optimization of the morphology and thickness of CIS layer and the device structure. PACS: 81.15.-z; 84.60.Jt; 73.40.Lq

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

2013-08-01

194

Electronic structure of indium tin oxide/nanocrystalline TiO2 interfaces as used in dye-sensitized solar cell devices  

NASA Astrophysics Data System (ADS)

Dye-sensitized solar cells are typically prepared under ambient conditions and contamination is inevitably introduced during the fabrication process. Hence, the electronic structure and charge injection properties of the indium tin oxide (ITO)/nanocrystalline titanium dioxide (TiO2) interface was studied by photoemission spectroscopy (PES) in the presence of environmental contaminants. The interface was formed by in situ multi-step electrospray thin film deposition of TiO2 nanoparticles onto ITO substrates cleaned prior in solvent under ambient conditions. In between deposition steps, the samples were characterized with PES yielding the band line-up at the ITO/TiO2 interface. In addition, the band line-up before and after annealing of the TiO2 layer was determined. The results of these measurements have in common that there are only small charge injection barriers between the valence bands of the oxides (˜0-0.2 eV), but more significant barriers for electron injection from TiO2 to ITO (˜0.3-0.5 eV), which has the potential to affect the performance of solar cell device structures. Another focus of the experiments was to investigate whether an earlier reported work function lowering measurement artifact occurring during ultraviolet photoemission spectroscopy (UPS) measurements on environmentally contaminated metal oxide surfaces would affect the characterization of ITO/TiO2 interfaces. For this purpose additional band line-up measurements using low intensity x-ray photoemission spectroscopy (LIXPS) were performed. LIXPS has been demonstrated to not cause the artifact, i.e., can be used to detect its occurrence. The results of these experiments show that the UV-induced work function reduction is not observed on the annealed interface, but that at contaminated interfaces care must be taken during data evaluation to take the artifact into account.

Gutmann, Sebastian; Wolak, Matthäus A.; Conrad, Matthew; Beerbom, Martin M.; Schlaf, Rudy

2011-06-01

195

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

NASA Astrophysics Data System (ADS)

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

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

2013-02-01

196

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

NASA Astrophysics Data System (ADS)

One approach to harvest a wide solar spectral solar energy is to stack two solar cells with different absorption characteristics in a tandem cell architecture. Herein, solution processed tandem solar cells, with highly transparent titanium oxide (TiO2) and graphene oxide (GO) as an efficient recombination layer, were designed, fabricated and characterized. We have adopted poly[(4,4'-bis(3-ethylhexyl)dithieno[3,2-b:''3'-d]silole)-2,6-diyl-alt-(2,5-(3-(2-ethylhexyl)thiophen-2-yl)thiazolo[5,4-d]thiazole]:indene-C60 bisadduct (PSEHTT:ICBA) and poly[(4,4'-bis(2-ethylhexyl)dithieno[3,2-b:2',3'-d]silole)-2,6-diyl-alt-(2,1,3-benzothiadiazole)-4,7-diyl]:[6,6]-phenyl-C70 butyric acid methyl ester (PSBTBT:PC70BM) as the active layers for the front and rear cells, respectively. The TiO2/GO serves as an electron and hole collecting and recombination layer. The tandem solar cells showed a high open circuit voltage (VOC) 1.62 V, a moderate short circuit current density (JSC) 8.23 mA cm-2, fill factor (FF) 62.98%, leading to the power conversion efficiency of 8.40%. The obtained VOC value of tandem solar cells is ideal for the summation of VOCs attained from front and rear cells and it is evident that our tandem solar cells are well connected in series. Moreover, this tandem cell exhibits a 20% drop in conversion efficiency under continuous AM illumination for 2880 h.One approach to harvest a wide solar spectral solar energy is to stack two solar cells with different absorption characteristics in a tandem cell architecture. Herein, solution processed tandem solar cells, with highly transparent titanium oxide (TiO2) and graphene oxide (GO) as an efficient recombination layer, were designed, fabricated and characterized. We have adopted poly[(4,4'-bis(3-ethylhexyl)dithieno[3,2-b:''3'-d]silole)-2,6-diyl-alt-(2,5-(3-(2-ethylhexyl)thiophen-2-yl)thiazolo[5,4-d]thiazole]:indene-C60 bisadduct (PSEHTT:ICBA) and poly[(4,4'-bis(2-ethylhexyl)dithieno[3,2-b:2',3'-d]silole)-2,6-diyl-alt-(2,1,3-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. Electronic supplementary information (ESI) available. See DOI: 10.1039/c3nr03068g

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

2013-10-01

197

Ag plasmonic nanostructures and a novel gel electrolyte in a high efficiency TiO2/CdS solar cell.  

PubMed

A novel photoanode architecture with plasmonic silver (Ag) nanostructures embedded in titania (TiO2), which served as the wide band gap semiconducting support and CdS quantum dots (QDs), as light absorbers, is presented. Ag nanostructures were prepared by a polyol method and are comprised of clumps of nanorods, 15-35 nm wide, interspersed with globular nanoparticles and they were characterized by a face centered cubic lattice. Optimization of Ag nanostructures was achieved on the basis of a superior power conversion efficiency (PCE) obtained for the cell with a Ag/TiO2/CdS electrode encompassing a mixed morphology of Ag nano-rods and particles, relative to analogous cells with either Ag nanoparticles or Ag nanorods. Interfacial charge transfer kinetics was unraveled by fluorescence quenching and lifetime studies. Ag nanostructures improve the light harvesting ability of the TiO2/CdS photoanode via (a) plasmonic and scattering effects, which induce both near- and far-field enhancements which translate to higher photocurrent densities and (b) charging effects, whereby, photoexcited electron transfer from TiO2 to Ag is facilitated by Fermi level equilibration. Owing to the spectacular ability of Ag nanostructures to increase light absorption, a greatly increased PCE of 4.27% and a maximum external quantum efficiency of 55% (at 440 nm) was achieved for the cell based on Ag/TiO2/CdS, greater by 42 and 66%, respectively, compared to the TiO2/CdS based cell. In addition, the liquid S(2-) electrolyte was replaced by a S(2-) gel containing fumed silica, and the redox potential, conductivity and p-type conduction of the two were deduced to be comparable. Although the gel based cells showed diminished solar cell performances compared to their liquid counterparts, nonetheless, the Ag/TiO2/CdS electrode continued to outperform the TiO2/CdS electrode. Our studies demonstrate that Ag nanostructures effectively capture a significant chunk of the electromagnetic spectrum and aid QD solar cells in delivering high power conversion efficiencies. PMID:25785507

Kumar, P Naresh; Deepa, Melepurath; Srivastava, Avanish Kumar

2015-04-01

198

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

199

Hole-transport materials with greatly-differing redox potentials give efficient TiO2-[CH3NH3][PbX3] perovskite solar cells.  

PubMed

Two diacetylide-triphenylamine hole-transport materials (HTM) with varying redox potential have been applied in planar junction TiO2-[CH3NH3]PbI3-xClx solar cells leading to high power-conversion efficiencies up to 8.8%. More positive oxidation potential of the HTM gives higher VOC and lower JSC illustrating the role of matching energy levels, however both HTMs gave efficient cells despite a difference of 0.44 V in their redox potentials. PMID:25504144

Abate, Antonio; Planells, Miquel; Hollman, Derek J; Barthi, Vishal; Chand, Suresh; Snaith, Henry J; Robertson, Neil

2015-01-28

200

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

201

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

NASA Astrophysics Data System (ADS)

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

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

2014-12-01

202

Effects of counter electrodes on photovoltaic performance of all-solid-state TiO2-based dye-sensitized solar cells  

NASA Astrophysics Data System (ADS)

In order to analyse the effects of counter electrodes on photovoltaic performance of dye-sensitized solar cells (DSSCs), different electrodes were used as the counter electrodes for all-solid-state TiO2-based DSSCs. An inorganic solid-state electrolyte, CsSnI2.95F0.05, was selected to couple with N719 dye-sensitized TiO2 nanorod arrays to fabricate the DSSCs. Fluorine doped tin oxide transparent conducting glass (FTO), platinum coated FTO (Pt/FTO), graphite coated FTO (graphite/FTO), and graphite coated common glass (graphite/glass) were investigated as the counter electrodes, and the cells composed of the corresponding electrodes above have power-conversion efficiencies of 2.17%, 9.84%, 7.62%, and 3.45%, respectively. Our findings indicate that due to its unique catalytic and conducting properties, graphite can replace both Pt and FTO as a counter electrode to reduce the fabrication cost of all-solid-state TiO2-based DSSCs.

Shang, Mingwei; Liu, Benjamin; Dong, Zhenhua; Dong, Zhenyu; Dong, Lifeng

2015-03-01

203

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

PubMed

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

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

2013-02-01

204

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

NASA Astrophysics Data System (ADS)

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

Madhu Mohan, Varishetty; Murakami, Kenji

2012-02-01

205

Band engineered ternary solid solution CdS(x)Se(1-x)-sensitized mesoscopic TiO(2) solar cells.  

PubMed

The optical band gap of the light absorber and the alignment of its bands with the underlying wide band gap metal oxide are critical for efficient light harvesting and charge separation in semiconductor-sensitized solar cells (SSCs). In practice, these two requirements are however not always fulfilled concomitantly in SSCs. Favourable band alignment in CdSe-sensitized TiO(2) requires utilization of quantum sized CdSe, which causes great losses in the harvesting of long wavelength photons due to quantum confinement effects. In the present study, ternary cadmium sulfoselenide (CdS(x)Se(1-x)), which has a tunable band gap between those of CdSe and CdS without reducing the dimension, was proposed as a sensitizer for TiO(2). CdS(x)Se(1-x) was successfully synthesized by alternately depositing CdS and CdSe layers under ambient conditions. SSCs utilizing CdS(x)Se(1-x)-sensitized TiO(2) yielded a power conversion efficiency of 4.05% under simulated AM1.5 100 mW cm(-2) illumination, rivalling the well-studied cascaded CdS/CdSe electrodes when an aqueous polysulfide solution was used as the electrolyte and Cu(2)S as the counter electrode. The findings of the present study provide an alternative and viable approach for optimizing the energetics of semiconductor sensitizers for efficient charge separation, while also maintaining good light harvesting. PMID:22466412

Hossain, Md Anower; Jennings, James Robert; Mathews, Nripan; Wang, Qing

2012-04-01

206

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

NASA Astrophysics Data System (ADS)

Porous TiO2 nanotube arrays with three-dimensional (3D) interconnectivity were prepared using a sol-gel process assisted by poly(vinyl chloride-graft-4-vinyl pyridine), PVC-g-P4VP graft copolymer and a ZnO nanorod template. A 7 µm long ZnO nanorod array was grown from the fluorine-doped tin oxide (FTO) glass via a liquid phase deposition method. The TiO2 sol-gel solution templated by the PVC-g-P4VP graft copolymer produced a random 3D interconnection between the adjacent ZnO nanorods during spin coating. Upon etching of ZnO, TiO2 nanotubes consisting of 10-15 nm nanoparticles were generated, as confirmed by wide-angle x-ray scattering (WAXS), energy-filtering transmission electron microscopy (EF-TEM) and field-emission scanning electron microscopy (FE-SEM). The ordered and interconnected nanotube architecture showed an enhanced light scattering effect and increased penetration of polymer electrolytes in dye-sensitized solar cells (DSSC). The energy conversion efficiency reached 1.82% for liquid electrolyte, and 1.46% for low molecular weight (Mw) and 0.74% for high Mw polymer electrolytes.

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

2011-09-01

207

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

208

Synthesis of hierarchical TiO2 flower-rod and application in CdSe/CdS co-sensitized solar cell  

NASA Astrophysics Data System (ADS)

A hierarchical double-layered TiO2 flower-rod structure composed of three-dimensional (3D) TiO2 flowers and one-dimensional (1D) nanorods on transparent fluorine-doped tin oxide (FTO) conducting glass has been synthesized by a facile hydrothermal method. The possible formation mechanism of the hierarchical architecture is also proposed. When used in CdSe/CdS quantum dots co-sensitized solar cells (QDSSCs), the 1D ordered rutile nanorods at bottom can accelerate the electron transfer rate by providing direct electrical pathway for photogenerated electrons, while the 3D flowers formed on the top of nanorods can increase the adsorption of QDs due to the enlarged areas, and can also be used as a scattering layer. The performance of the CdSe/CdS/TiO2 flower-rod solar cell can achieve a short-circuit current density (Jsc) of 13.46 mA cm-2, and a open-circuit voltage (Voc) of 0.42 V, with a maximum power conversion efficiency of 2.31% under one sun illumination (AM 1.5 G, 100 mW cm-2), which is greatly higher than that of CdSe/CdS/TiO2 nanorod solar cell (1.63%).

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

2014-12-01

209

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

Microsoft Academic Search

Crack-free TiO2 nanotube (NT) membranes were obtained by short time re-anodization of a sintered TiO2 NT array on Ti foil, followed by dilute HF etching at room temperature. The resulting freestanding TiO2 membranes were opaque with a slight yellow color having one end open and another end closed. The membranes were then fixed on transparent fluorine-tin-oxide glass using a thin

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

2011-01-01

210

Enhanced performance of bi-layer Nb2O5 coated TiO2 nanoparticles/nanowires composite photoanode in dye-sensitized solar cells  

NASA Astrophysics Data System (ADS)

Dye sensitized solar cells (DSSCs) were fabricated based on coumarin NKX-2700 dye sensitized bi-layer photoanode and quasi-solid state electrolyte sandwiched together with cobalt sulfide coated counter electrode. A novel bi-layer photoanode has been prepared using composite mixtures of 90 wt.% TiO2 nanoparticles + 10 wt.% TiO2 nanowires (TNPWs) as active layer and Nb2O5 is coated on the active layer, which acts as scattering layer. Hafnium oxide (HfO2) was applied over the TNPWs/Nb2O5 photoanode film, as a blocking layer. TiO2 nanoparticles (TNPs), TiO2 nanowires (TNWs) and TNPWs/Nb2O5 were characterized by X-ray diffractometer (XRD), scanning electron microscope (SEM) and transmission electron microscope (TEM). The sensitizing organic dye coumarin NKX-2700 displayed maximum absorption wavelength (?max) at 525 nm, which could be observed from the UV-vis spectrum. DSSC-1 fabricated with composite bi-layer photoanode revealed enhanced photo-current efficiency (PCE) as compared to other DSSCs and illustrated photovoltaic parameters; short-circuit current JSC = 18 mA/cm2, open circuit voltage (VOC) = 700 mV, fill factor (FF) = 64% and PCE (?) = 8.06%. The electron transport and charge recombination behaviors of DSSCs were investigated by electrochemical impedance spectra (EIS) and the results illustrated that the DSSC-1 showed the lowest charge transport resistance (Rtr) and the longest electron lifetime (?eff). Therefore, in the present investigation, it could be concluded that the novel bi-layer photoanode with blocking layer increased the short circuit current, electron transport and suppressed the recombination of charge carriers at the photoanode/dye/electrolyte interface in DSSC-1.

Maheswari, D.; Venkatachalam, P.

2014-11-01

211

Direct assembly of preformed nanoparticles and graft copolymer for the fabrication of micrometer-thick, organized TiO2 films: high efficiency solid-state dye-sensitized solar cells.  

PubMed

Solid-state dye-sensitized solar cell with 7.1% efficiency at 100 mW/cm(2) is reported, one of the highest observed for N719 dye. Excellent performance was achieved via a graft copolymer-templated, organized mesoporous TiO(2) film with a large surface area using spindle-shaped, preformed TiO(2) nanoparticles and solid polymer electrolyte. PMID:22213245

Ahn, Sung Hoon; Chi, Won Seok; Park, Jung Tae; Koh, Jong Kwan; Roh, Dong Kyu; Kim, Jong Hak

2012-01-24

212

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

PubMed

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

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

2013-01-01

213

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

NASA Astrophysics Data System (ADS)

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

Ke, Chun-Ren; Ting, Jyh-Ming

2012-06-01

214

Systematic investigation of structural and morphological studies on doped TiO2 nanoparticles for solar cell applications  

NASA Astrophysics Data System (ADS)

Optical, structural and thermal properties of the doped with different ions (transition metals, other metals or post transition metals, non-metals, alkali metals and lanthanides) in TiO2 nanocrystals were investigated. The doped nanoparticles were synthesized by modified chemical method. Ethanol-deionised water mixer (20:1) was used as solvent for synthesize of the undoped and doped TiO2 nanoparticles. Systematic studies on structural and morphological changes by thermal treatment on TiO2 were examined. It has been observed that with Eu and Al doping TiO2, the phase transition temperature for anatase to rutile phase increased. Blue and red shifting absorptions were observed for doped TiO2 in visible region. Among the dopant, significant blue shift was obtained for Cu, Cd, Ag, Y, Ce and In doped TiO2 and red shift was obtained for Zr, Sm, Al, Na, S, Fe, Ni, Eu and Gd doped TiO2 nanoparticles.

Murugadoss, G.; Jayavel, R.; Rajesh Kumar, M.

2014-12-01

215

Ultrahigh vacuum preparation and characterization of TiO2/CdTe interfaces: Electrical properties and implications for solar cells  

NASA Astrophysics Data System (ADS)

The semiconductor cadmium telluride (CdTe) has been grown in ultrahigh vacuum by standard molecular beam epitaxy on thin films of anatase titanium dioxide (TiO2) to investigate the interface properties of solid state injection type solar cells. These interfaces were studied by photoelectron spectroscopy and the band alignment was determined. The interface is characterized by a valence band offset ?EV of 2.6 eV, a conduction band offset ?EC of 0.7 eV, and a strong dipole ? of about 0.9 eV in contradiction to the electron affinity rule (Anderson model). Therefore this system is not very favorable for solar power generation.

Tiefenbacher, S.; Pettenkofer, C.; Jaegermann, W.

2002-02-01

216

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

PubMed

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

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

2013-02-21

217

3D hierarchical rutile TiO2 and metal-free organic sensitizer producing dye-sensitized solar cells 8.6% conversion efficiency.  

PubMed

Three-dimensional (3D) hierarchical nanoscale architectures comprised of building blocks, with specifically engineered morphologies, are expected to play important roles in the fabrication of 'next generation' microelectronic and optoelectronic devices due to their high surface-to-volume ratio as well as opto-electronic properties. Herein, a series of well-defined 3D hierarchical rutile TiO2 architectures (HRT) were successfully prepared using a facile hydrothermal method without any surfactant or template, simply by changing the concentration of hydrochloric acid used in the synthesis. The production of these materials provides, to the best of our knowledge, the first identified example of a ledgewise growth mechanism in a rutile TiO2 structure. Also for the first time, a Dye-sensitized Solar Cell (DSC) combining a HRT is reported in conjunction with a high-extinction-coefficient metal-free organic sensitizer (D149), achieving a conversion efficiency of 5.5%, which is superior to ones employing P25 (4.5%), comparable to state-of-the-art commercial transparent titania anatase paste (5.8%). Further to this, an overall conversion efficiency 8.6% was achieved when HRT was used as the light scattering layer, a considerable improvement over the commercial transparent/reflector titania anatase paste (7.6%), a significantly smaller gap in performance than has been seen previously. PMID:25167837

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

2014-01-01

218

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

NASA Astrophysics Data System (ADS)

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

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

2014-08-01

219

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

NASA Astrophysics Data System (ADS)

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

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

2014-01-01

220

The real TiO2/HTM interface of solid-state dye solar cells: role of trapped states from a multiscale modelling perspective  

NASA Astrophysics Data System (ADS)

In this paper we present a multiscale simulation of charge transport in a solid-state dye-sensitized solar cell, where the real morphology between TiO2 and the hole transport material is included. The geometry of the interface is obtained from an electron tomography measurement and imported in a simulation software. Charge distribution, electric field and current densities are computed using the drift-diffusion model. We use this approach to investigate the electrostatic effect of trap states at the interface between the electron and hole transport materials. The simulations show that when the trapped electrons are not screened by external additives, the dynamics of holes is perturbed. Holes accumulate at the interface, enhancing recombination and reducing cell performance.In this paper we present a multiscale simulation of charge transport in a solid-state dye-sensitized solar cell, where the real morphology between TiO2 and the hole transport material is included. The geometry of the interface is obtained from an electron tomography measurement and imported in a simulation software. Charge distribution, electric field and current densities are computed using the drift-diffusion model. We use this approach to investigate the electrostatic effect of trap states at the interface between the electron and hole transport materials. The simulations show that when the trapped electrons are not screened by external additives, the dynamics of holes is perturbed. Holes accumulate at the interface, enhancing recombination and reducing cell performance. Electronic supplementary information (ESI) available. See DOI: 10.1039/c4nr05208k

Gagliardi, Alessio; Auf der Maur, Matthias; Gentilini, Desiree; di Fonzo, Fabio; Abrusci, Agnese; Snaith, Henry J.; Divitini, Giorgio; Ducati, Caterina; di Carlo, Aldo

2014-12-01

221

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

PubMed

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

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

2012-08-01

222

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

223

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

224

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

225

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

PubMed

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

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

2014-01-21

226

Solid-state and flexible solar cells based on dye-sensitized TiO2: study by electrochemical impedance spectroscopy  

NASA Astrophysics Data System (ADS)

Dye sensitized TiO2 solar cells were assembled using rigid or flexible transparent electrodes (a conductive film deposited on glass or poly(ethylene terephthalate) as substrates and a polymer electrolyte based on (formula available in paper) and poly(epichlorohydrin-co-ethylene oxide). The cells were characterized by current-potential curves and electrochemical impedance spectroscopy under different light intensities. Under 100 mWcm-2 illumination, the rigid cell exhibited an open circuit potential VOC=0.75V, a short-circuit photocurrent ISC=2.5 mAcm-2 and an efficiency (eta) =0.9%; for the flexible cell, VOC=0.83V and (eta) and ISC were almost 10 times smaller. Under illumination, impedance spectra exhibited three semi-circles for the rigid cell. For the flexible cell the time constants were not well defined. In the dark, both systems presented very high impedance. The differences in the efficiency and the impedance spectra of both cells were compared and discussed.

Longo, Claudia; Nogueira, Flavia; Cachet, Hubert; De Paoli, Marco-Aurelio

2002-02-01

227

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

NASA Astrophysics Data System (ADS)

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

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

2014-08-01

228

Chemical reactions in TiO2/SnO2/TiCl4 hybrid electrodes and their impacts to power conversion efficiency of dye-sensitized solar cells  

NASA Astrophysics Data System (ADS)

This study examined the applicability of TiO2/SnO2/TiCl4 hybrid electrodes in dye-sensitized solar cells (DSSCs) by combining chemical modeling with experimentation. The interfacial chemical reactions in a TiO2/SnO2/TiCl4 system were simulated using a thermochemistry software package, which led to the design and testing of hybrid working electrodes. Chemical thermodynamic modeling proved that TiCl4 is an effective agent in removing Tin+ (n<4) and Snm+ (m<4) ion impurities from dry-mixed TiO2/SnO2 composite particles. Our results demonstrate that the power conversion efficiency of DSSC with a TiO2/SnO2/TiCl4 hybrid electrode exceeds that of the conventional DSSC with a TiO2 electrode due to the effects of light-scattering and the formation of additional absorbance (SnCl2), which is an unexpected side effect of TiCl4 treatment enabling the absorption of visible light. The proposed approach is ideally suited to establishing relationships between chemistry theory and the structure and performance of advanced DSSCs as well as photo-electro-chemical systems.

Chou, Chuen-Shii; Jhang, Jhih-Wei; Chou, Sheng-Wei; Wu, Ping

2015-01-01

229

Nanosilver-decorated TiO2 nanofibers coated with a SiO2 layer for enhanced light scattering and localized surface plasmons in dye-sensitized solar cells.  

PubMed

Enhanced harvesting of visible light is vital to the development of highly efficient dye-sensitized solar cells (DSSCs). Nanosilver-decorated TiO2 nanofibers (Ag@TiO2 NFs) were synthesized by depositing chemically reduced Ag ions onto the surface of electrospun TiO2 nanofibers (TiO2 NFs). The prepared Ag@TiO2 NFs were coated with SiO2 (SiO2@Ag@TiO2 NFs) by using PVP as coupling agent for protecting corrosion of Ag nanoparticle by I(-)/I3(-) solution. The fabricated SiO2@Ag@TiO2 NFs demonstrated a synergistic effect of light scattering and surface plasmons, leading to an enhanced light absorption. Moreover, an anode consisting of SiO2@Ag@TiO2 NFs incorporating TiO2 nanoparticles (NPs) increased light harvesting without substantially sacrificing dye attachment. The power conversion efficiency increased from 6.8 to 8.7?% for a thick film (10??m), that is, 28?%. These results suggest that SiO2@Ag@TiO2 NFs are promising materials for enhanced light absorption in dye-sensitized solar cells. PMID:23934778

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

2013-09-23

230

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

PubMed

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

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

2013-04-18

231

Efficiency enhancement in dye-sensitized solar cells by interfacial modification of conducting glass\\/mesoporous TiO 2 using a novel ZnO compact blocking film  

Microsoft Academic Search

A novel and thin ZnO compact blocking film is employed at the interface of fluorine-doped tin oxide (FTO) substrate and mesoporous TiO2, and its influence on dye-sensitized solar cells (DSSCs) is investigated. The ZnO film prepared by spin-coating method on FTO is characterized by energy-dispersive X-ray spectroscopy (EDX), scanning electron microscopy (SEM), and UV–vis spectrophotometer. The ZnO film is firstly

Yumin Liu; Xiaohua Sun; Qidong Tai; Hao Hu; Bolei Chen; Niu Huang; Bobby Sebo; Xing-zhong Zhao

2011-01-01

232

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

PubMed

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

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

2012-06-27

233

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

234

Oriented Hierarchical Porous TiO2 Nanowires on Ti Substrate: Evolution of Nanostructures for Dye-Sensitized Solar Cells  

E-print Network

cells, liquid crystal displays (LCD), transparent conducting films (TCFs), lithium-ion batteries, etc attention due to their low cost and extensive applications in portable devices [5­7]. Therefore, metal the understanding on the establishment of the nanostructures is essential for the practical applications

Park, Byungwoo

235

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

236

Arginine Interactions with Anatase TiO2 (100) Surface and the Perturbation of 49Ti NMR Chemical Shifts - A DFT Investigation: Relevance to Renu-Seeram Bio Solar Cell  

SciTech Connect

Density functional theoretical calculations have been utilized to investigate the interaction of the amino acid arginine with the (100) surface of anatase and the reproduction of experimentally measured 49Ti NMR chemical shifts of anatase. Significant binding of arginine through electrostatic interaction and hydrogen bonds of the arginine guanidinium protons to the TiO2 surface oxygen atoms is observed, allowing attachment of proteins to titania surfaces in the construction of bio-sensitized solar cells. GIAO-B3LYP/6-31G(d) NMR calculation of a three-layer model based on the experimental structure of this TiO2 modification gives an excellent reproduction of the experimental value (-927 ppm) within +/- 7 ppm, however, the change in relative chemical shifts, EFGs and CSA suggest that the effect of the electrostatic arginine binding might be too small for experimental detection.

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

2011-06-01

237

Polyol thermolysis synthesis of TiO2 nanoparticles and its paste formulation to fabricate photoanode for dye-sensitized solar cells  

NASA Astrophysics Data System (ADS)

Titanium dioxide (TiO2) nanoparticles (NPs) were prepared by a simple polyol thermolysis process using various mole ratios of titanium tetrachloride (TiCl4) and polyvinylpyrrolidone (PVP). The prepared TiO2 NPs were characterized by TG/DTA, XRD, SEM, and BET analysis. The TiO2 NPs obtained using 0.1 M of TiCl4 and 0.02 M of PVP have high surface area with lesser particles size than the same obtained using 0.1 M of TiCl4 with other mole ratios of PVP. The high surface area TiO2 NPs were used to formulate TiO2 paste. The impact of ethyl cellulose, terpineol, and dibutyl phthalate in the formulation of TiO2 paste was optimized with respect to standard TiO2 paste (Dyesol Ltd.) on the adsorption of dye was studied by UV-Vis spectroscopy. The photovoltaic performance of DSSCs fabricated using the formulated TiO2 paste has achieved 97.83 % of power conversion efficiency (PCE) (? = 4.5 %) with respect to the standard TiO2 paste (Dyesol Ltd.) and its PCE were found to be 4.6 % (?). This PCE value was nearly closer to that of the same DSSC fabricated using the standard TiO2 paste (Dyesol Ltd.) and higher than the P25 TiO2 (Degussa) paste and its achieved PCE were found to be 86.04 %.

Pratheep, P.; Vijayakumar, E.; Subramania, A.

2015-01-01

238

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

E-print Network

Surface Passivation of Nanoporous TiO2 via Atomic Layer Deposition of ZrO2 for Solid-State Dye-OMeTAD). By depositing ZrO2 films with angstrom-level precision, coating the mesoporous TiO2 produces over a two measurements provide evidence that the ZrO2 coating reduces recombination losses at the TiO2/spiro

239

Preparation of SiO2/TiO2 and TiO2/TiO2 micropattern and their effects on platelet adhesion and endothelial cell regulation  

NASA Astrophysics Data System (ADS)

TiO2 films were applied on blood contact biomaterials for its excellent biocompatibility. The topological structure of the biomaterial surfaces have a significant impact on cell adhesion, spreading and proliferation. Thus, it is anticipated that the combination of TiO2 film deposition and surface micro-patterning will provide a potential application for cardiovascular implants materials. In this work, TiO2/TiO2 and SiO2/TiO2 micro-groove/ridge stripes on Si (100) were prepared by photolithography, wet etching and unbalanced magnetron sputtering (UBMS). Their surface morphology, chemical composition and wettability were investigated. The crystal structure of TiO2 films was characterised by X-ray diffraction (XRD). Platelet adhesion on the SiO2/TiO2 and TiO2/TiO2 surfaces was tested, and the morphology and behaviour of endothelial cells cultured on the micropatterned surfaces were observed. It was proved that the SiO2/TiO2 pattern could reduce platelet adhesion and aggregation compared with TiO2/TiO2 pattern, endothelial cells grew along the micro-stripes and their behaviour could be effectively regulated by micropatterned surface. So, it is suggested that the micropatterned SiO2/TiO2 surface can contribute more bio-compatible function of regulating and coordinating the behaviour of endothelial cells and platelets.

Li, Jing-an; Yang, Ping; Zhang, Kun; Ren, Hui-lan; Huang, Nan

2013-07-01

240

Room Temperature Synthesis of Highly Compact TiO2 Coatings by Vacuum Kinetic Spraying to Serve as a Blocking Layer in Polymer Electrolyte-Based Dye-Sensitized Solar Cells  

NASA Astrophysics Data System (ADS)

Vacuum kinetic spraying (VKS) was used to form a blocking layer (BL) in order to increase the efficiency of dye-sensitized solar cells. Nano-sized TiO2 powders were deposited on fluorine-doped tin oxide (FTO) glass while varying the coating parameters including the mass flow, substrate transverse speed, and number of coating passes in order to control the thickness of the BL. Compared to the cell without a BL, the open-circuit voltage and short-circuit current density of the solar cell with a VKS-coated BL were noticeably improved. Consequently, the photoconversion efficiency increased up to 5.6%, which is significantly higher than that of a spin-coated BL.

Heo, Jeeae; Sudhagar, P.; Park, Hyungkwon; Cho, Woohyung; Kang, Yong Soo; Lee, Changhee

2015-02-01

241

Growth of nanocrystalline TiO 2 films by pulsed-laser-induced liquid-deposition method and preliminary applications for dye-sensitized solar cells  

Microsoft Academic Search

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\\u000a 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

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

2010-01-01

242

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. PMID:21777458

2011-01-01

243

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

244

Distribution of graphene oxide and TiO2-graphene oxide composite in A549 cells.  

PubMed

Graphene and its derivatives are increasingly applied in nanoelectronics, biosensing, drug delivery, and biomedical applications. However, the information about its cytotoxicity remains limited. Herein, the distribution and cytotoxicity of graphene oxide (GO) and TiO2-graphene oxide composite (TiO2-GO composite) were evaluated in A549 cells. Cell viability and cell ultrastructure were measured. Our results indicated that GO could enter A549 cells and located in the cytoplasm and nucleus without causing any cell damage. TiO2 nanoparticles and GO would be separated after TiO2-GO composite entered A549 cells. TiO2-GO composite could induce cytotoxicity similar to TiO2 nanoparticles, which was probably attributed to oxidative stress. These results should be considered in the development of biological applications of GO and TiO2-GO composite. PMID:24869803

Jin, Chan; Wang, Fude; Tang, Ying; Zhang, Xiangzhi; Wang, Jianqiang; Yang, Yongji

2014-06-01

245

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

246

Ruthenium Sensitizers with a Hexylthiophene-Modified Terpyridine Ligand for Dye-Sensitized Solar Cells: Synthesis, Photo- and Electrochemical Properties, and Adsorption Behavior to the TiO2 Surface.  

PubMed

Two novel ruthenium sensitizers with a hexylthiophene-modified terpyridine ligand (TUS-35 and TUS-36) were synthesized to improve the molar absorptivity of the previously reported ruthenium sensitizer (TBA)[Ru{4'-(3,4-dicarboxyphenyl)-4,4?-dicarboxyterpyridine}(NCS)3], TBA = tetrabutylammonium (TUS-21). A relatively strong absorption appeared at ?380 nm, and the molar absorption coefficient at the metal-to-ligand charge transfer (MLCT) band decreased in TUS-35 by introducing a 2-hexylthiophene unit to the 5-position of the terpyridine-derived ligand. For comparison, a relatively strong absorption was observed at ?350 nm without decreasing the molar absorption coefficient at the MLCT band in TUS-36 by introducing a 2-hexylthiophene unit to the 4-position of the terpyridine-derived ligand. On the other hand, the energy levels of the highest occupied molecular orbitals and the lowest unoccupied molecular orbitals of these two sensitizers were found to be almost equal to those of TUS-21. The adsorption behavior of TUS-35 and TUS-36 was similar to that of (TBA)[Ru{4'-(3,4-dicarboxyphenyl)terpyridine}(NCS)3] (TUS-20), which binds to the TiO2 surface by using the 3,4-dicarboxyphenly unit, rather than that of TUS-21, which adsorbs to the TiO2 photoelectrode using one of the carboxyl groups at the terminal pyridines of the terpyridine-derived ligand. Therefore, TUS-35 and TUS-36 are considered to bind to the TiO2 surface by using the 3,4-dicarboxyphenly unit just like TUS-20. The dye-sensitized solar cells (DSCs) with TUS-35 and TUS-36 showed a relatively lower conversion efficiency (6.4% and 5.7%, respectively) compared to the DSC with TUS-21 (10.2%). Open-circuit photovoltage decay and electrochemical impedance spectroscopy measurements revealed that the promoted charge recombination and/or charge transfer of the injected electrons in the TiO2 photoelectrode is a main reason for the inferior performances of TUS-35 and TUS-36. PMID:25587752

Ozawa, Hironobu; Yamamoto, Yasuyuki; Kawaguchi, Hiroki; Shimizu, Ryosuke; Arakawa, Hironori

2015-02-11

247

Exploring ruthenium dye synthesis and TiO2-dye-I-/I3- electron transfer reactions in a dye-sensitised solar cell  

E-print Network

Octahedral, six co-ordinate ruthenium complexes containing acid substituted polypyridyl ligands have proved particularly successful as dyes for Dye-Sensitised Solar Cells (DSSCs); thus there have been hundreds, if not ...

Chadwick, Nina

2013-11-28

248

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

PubMed Central

A mesoscopic methylammonium lead iodide (CH3NH3PbI3) perovskite/TiO2 heterojunction solar cell is developed with low-cost carbon counter electrode (CE) and full printable process. With carbon black/spheroidal graphite CE, this mesoscopic heterojunction solar cell presents high stability and power conversion efficiency of 6.64%, which is higher than that of the flaky graphite based device and comparable to the conventional Au version. PMID:24185501

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

2013-01-01

249

Optoelectronic Studies of Methylammonium Lead Iodide Perovskite Solar Cells with Mesoporous TiO2: Separation of Electronic and Chemical Charge Storage, Understanding Two Recombination Lifetimes, and the Evolution of Band Offsets during J-V Hysteresis.  

PubMed

Methylammonium lead iodide (MAPI) cells of the design FTO/sTiO2/mpTiO2/MAPI/Spiro-OMeTAD/Au, where FTO is fluorine-doped tin oxide, sTiO2 indicates solid-TiO2, and mpTiO2 is mesoporous TiO2, are studied using transient photovoltage (TPV), differential capacitance, charge extraction, current interrupt, and chronophotoamperometry. We show that in mpTiO2/MAPI cells there are two kinds of extractable charge stored under operation: a capacitive electronic charge (?0.2 ?C/cm(2)) and another, larger charge (40 ?C/cm(2)), possibly related to mobile ions. Transient photovoltage decays are strongly double exponential with two time constants that differ by a factor of ?5, independent of bias light intensity. The fast decay (?1 ?s at 1 sun) is assigned to the predominant charge recombination pathway in the cell. We examine and reject the possibility that the fast decay is due to ferroelectric relaxation or to the bulk photovoltaic effect. Like many MAPI solar cells, the studied cells show significant J-V hysteresis. Capacitance vs open circuit voltage (Voc) data indicate that the hysteresis involves a change in internal potential gradients, likely a shift in band offset at the TiO2/MAPI interface. The TPV results show that the Voc hysteresis is not due to a change in recombination rate constant. Calculation of recombination flux at Voc suggests that the hysteresis is also not due to an increase in charge separation efficiency and that charge generation is not a function of applied bias. We also show that the J-V hysteresis is not a light driven effect but is caused by exposure to electrical bias, light or dark. PMID:25785843

O'Regan, Brian C; Barnes, Piers R F; Li, Xiaoe; Law, Chunhung; Palomares, Emilio; Marin-Beloqui, Jose M

2015-04-22

250

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

Microsoft Academic Search

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

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

2006-01-01

251

Photocurrent induced by conducting channels of hole transporting layer to adjacent photoactive perovskite sensitized TiO2 thin film: solar cell paradigm.  

PubMed

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

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

2014-11-01

252

Growth of TiO 2 nanosheet-array thin films by quick chemical bath deposition for dye-sensitized solar cells  

Microsoft Academic Search

Rutile TiO2 nanofilms, which were composed of many nanosheet-array domains with different orientations, were synthesized directly on\\u000a fluorine-doped SnO2 conductive glass (FTO) substrates by a chemical deposition method in a short time in this paper. The average thickness of\\u000a the nanosheets is about 10 nm; the nanosheets in each domain were parallel to each other and perpendicular to the substrate.

Hu Zhu; Junyou Yang; Shuanglong Feng; Ming Liu; Jiansheng Zhang; Gen Li

253

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

PubMed Central

TiO2 hierarchical nanostructures with secondary growth have been successfully synthesized on electrospun nanofibers via surfactant-free hydrothermal route. The effect of hydrothermal reaction time on the secondary nanostructures has been studied. The synthesized nanostructures comprise electrospun nanofibers which are polycrystalline with anatase phase and have single crystalline, rutile TiO2 nanorod-like structures growing on them. These secondary nanostructures have a preferential growth direction [110]. UV–vis spectroscopy measurements point to better dye loading capability and incident photon to current conversion efficiency spectra show enhanced light harvesting of the synthesized hierarchical structures. Concomitantly, the dye molecules act as spacers between the conduction band electrons of TiO2 and holes in the hole transporting medium, i.e., spiro-OMeTAD and thus enhance open circuit voltage. The charge transport and recombination effects are characterized by electrochemical impedance spectroscopy measurements. As a result of improved light harvesting, dye loading, and reduced recombination losses, the hierarchical nanofibers yield 2.14% electrochemical conversion efficiency which is 50% higher than the efficiency obtained by plain nanofibers. PMID:24410851

2014-01-01

254

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

NASA Astrophysics Data System (ADS)

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.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. Electronic supplementary information (ESI) available: The details about the instrument used for various characterizations and figures related to FE-SEM analysis, EDS analysis, photoluminescence (PL) and LASER Raman study are provided. Table related to FT-IR analysis is also provided. See DOI: 10.1039/c4nr01836b

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

2014-06-01

255

Enhanced Performance of CdS/CdSe Quantum Dot Cosensitized Solar Cells via Homogeneous Distribution of Quantum Dots in TiO2  

E-print Network

a successive ion layer absorption and reaction (SILAR) method and a chemical bath deposition (CBD) methodEnhanced Performance of CdS/CdSe Quantum Dot Cosensitized Solar Cells via Homogeneous Distribution optimized for better distribution of quantum dots to enhance the performance of CdS/CdSe quantum dot

Cao, Guozhong

256

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

Microsoft Academic Search

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

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

2011-01-01

257

Surface Roughness Characterization of ZnO: TiO2-Organic Blended Solar Cells Layers by Atomic Force Microscopy and Fractal Analysis  

NASA Astrophysics Data System (ADS)

The objective of this work is to quantitatively characterize the 3D complexity of ZnO:TiO2-organic blended solar cells layers by atomic force microscopy and fractal analysis. ZnO:TiO2-organic blended solar cells layers were investigated by AFM in tapping-mode in air, on square areas of 25 ?m2. A detailed methodology for ZnO:TiO2-organic blended solar cells layers surface fractal characterization, which may be applied for AFM data, is presented. Detailed surface characterization of the surface topography was obtained using statistical parameters, according with ISO 25178-2: 2012. The fractal dimensions Df values (all with average ± standard deviation), obtained with morphological envelopes method, for: blend D1 (P3HT:PCBM:ZnO:TiO2 blend with ratio 1:0.35:0.175:0.175 mg in 1 ml of Chlorobenzene) is Df = 2.55 ± 0.01; and for blend D2 (P3HT:PCBM:ZnO:TiO2 blend with ratio 1:0.55:0.075:0.075 mg in 1 ml of Chlorobenzene) is Df = 2.45 ± 0.01. Denoting the ratios in 1 ml of Chlorobenzene with D1 and D2 articles. The 3D surface roughness of samples revealed a fractal structure at nanometer scale. Fractal and AFM analysis may assist manufacturers in developing ZnO:TiO2-organic blended solar cells layers with better surface characteristics and provides different yet complementary information to that offered by traditional surface statistical parameters.

??lu, ?tefan; Stach, Sebastian; Ikram, Muhammad; Pathak, Dinesh; Wagner, Tomas; Nunzi, Jean-Michel

2014-09-01

258

Stoichiometry gradient, cation interdiffusion, and band alignment between a nanosized TiO2 blocking layer and a transparent conductive oxide in dye-sensitized solar cell front contacts.  

PubMed

An angle-resolved photoemission spectroscopy study allowed us to identify cation interdiffusion and stoichiometry gradients at the interface between a nanosized TiO2 blocking layer and a transparent conductive Cd-Sn oxide substrate. A stoichiometry gradient for the Sn cations is already found in the bare Cd-Sn oxide layer. When TiO2 ultrathin layers are deposited by RF sputtering on the Cd-Sn oxide layer, Ti is found to partially replace Sn, resulting in a Cd-Sn-Ti mixed oxide layer with a thickness ranging from 0.85 to 3.3 nm. The band gap profile across the junction has been reconstructed for three TiO2 layers, resulting in a valence band offset decrease (and a conduction band offset increase) with the blocking layer thickness. The results are related to the cell efficiencies in terms of charge injection and recombination processes. PMID:25469853

Salvinelli, Gabriele; Drera, Giovanni; Baratto, Camilla; Braga, Antonio; Sangaletti, Luigi

2015-01-14

259

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

260

Characterization and improved solar light activity of vanadium doped TiO2/diatomite hybrid catalysts.  

PubMed

V-doped TiO2/diatomite composite photocatalysts with different vanadium concentrations were synthesized by a modified sol-gel method. The diatomite was responsible for the well dispersion of TiO2 nanoparticles on the matrix and consequently inhibited the agglomeration. V-TiO2/diatomite hybrids showed red shift in TiO2 absorption edge with enhanced absorption intensity. Most importantly, the dopant energy levels were formed in the TiO2 bandgap due to V(4+) ions substituted to Ti(4+) sites. The 0.5% V-TiO2/diatomite photocatalyst displayed narrower bandgap (2.95 eV) compared to undoped sample (3.13 eV) and other doped samples (3.05 eV) with higher doping concentration. The photocatalytic activities of V doped TiO2/diatomite samples for the degradation of Rhodamine B under stimulated solar light illumination were significantly improved compared with the undoped sample. In our case, V(4+) ions incorporated in TiO2 lattice were responsible for increased visible-light absorption and electron transfer to oxygen molecules adsorbed on the surface of TiO2 to produce superoxide radicals ?O2(-), while V(5+) species presented on the surface of TiO2 particles in the form of V2O5 contributed to e(-)-h(+) separation. In addition, due to the combination of diatomite as support, this hybrid photocatalyst could be separated from solution quickly by natural settlement and exhibited good reusability. PMID:25497036

Wang, Bin; Zhang, Guangxin; Leng, Xue; Sun, Zhiming; Zheng, Shuilin

2015-03-21

261

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

SciTech Connect

Nanostructured WO3/TiO2 nanotubes with properties that enhance solar photoconversion reactions were developed, characterized and tested. The TiO2 nanotubes were prepared by anodization of Ti foil, and WO3 was electrodeposited on top of the nanotubes. SEM images show that these materials have the same ordered structure as TiO2 nanotubes, with an external nanostructured WO3 layer. Diffuse reflectance spectra showed an increase in the visible absorption relative to bare TiO2 nanotubes, and in the UV absorption relative to bare WO3 films. Incident simulated solar photon-to-current efficiency increased from 30% (for bare WO3) to 50% (for WO3/TiO2 composites). With the addition of diverse organic pollutants, the photocurrent densities exhibited more than a 5-fold increase. Chemical oxygen demand measurements showed the simultaneous photodegradation of organic pollutants. The results of this work indicate that the unique structure and composition of these composite materials enhance the charge carrier transport and optical properties compared with the parent materials.

Reyes, Karla Rosa; Robinson, David B.

2013-05-01

262

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

PubMed Central

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. PMID:24256849

2013-01-01

263

Size-tunable TiO2 nanorod microspheres synthesised via a one-pot solvothermal method and used as the scattering layer for dye-sensitized solar cells.  

PubMed

TiO2 microspheres assembled by single crystalline rutile TiO2 nanorods were synthesized by one-pot solvothermal treatment at 180 °C based on an aqueous-organic mixture solution containing n-hexane, distilled water, titanium n-butoxide and hydrochloric acid. The spheres had a radiative structure from the center, and their diameters were controlled in the range from 1 to 5 ?m by adjusting the volume of the reactant water. Nitrogen adsorption-desorption isotherms showed that all the as-prepared microspheres had relatively high specific surface areas of about 50 m(2) g(-1). The 1 ?m sized TiO2 nanorod microspheres were fabricated as a scattering overlayer in DSSCs, leading to a remarkable improvement in the power conversion efficiency: 8.22% of the bi-layer DSSCs versus 7.00% for the reference cell made of a single-layer film prepared from nanocrystalline TiO2. Such improvement was mainly attributed to the enhanced light harvesting and dye loading brought by the effective scattering centers. PMID:24173030

Rui, Yichuan; Li, Yaogang; Zhang, Qinghong; Wang, Hongzhi

2013-12-21

264

Size-tunable TiO2 nanorod microspheres synthesised via a one-pot solvothermal method and used as the scattering layer for dye-sensitized solar cells  

NASA Astrophysics Data System (ADS)

TiO2 microspheres assembled by single crystalline rutile TiO2 nanorods were synthesized by one-pot solvothermal treatment at 180 °C based on an aqueous-organic mixture solution containing n-hexane, distilled water, titanium n-butoxide and hydrochloric acid. The spheres had a radiative structure from the center, and their diameters were controlled in the range from 1 to 5 ?m by adjusting the volume of the reactant water. Nitrogen adsorption-desorption isotherms showed that all the as-prepared microspheres had relatively high specific surface areas of about 50 m2 g-1. The 1 ?m sized TiO2 nanorod microspheres were fabricated as a scattering overlayer in DSSCs, leading to a remarkable improvement in the power conversion efficiency: 8.22% of the bi-layer DSSCs versus 7.00% for the reference cell made of a single-layer film prepared from nanocrystalline TiO2. Such improvement was mainly attributed to the enhanced light harvesting and dye loading brought by the effective scattering centers.TiO2 microspheres assembled by single crystalline rutile TiO2 nanorods were synthesized by one-pot solvothermal treatment at 180 °C based on an aqueous-organic mixture solution containing n-hexane, distilled water, titanium n-butoxide and hydrochloric acid. The spheres had a radiative structure from the center, and their diameters were controlled in the range from 1 to 5 ?m by adjusting the volume of the reactant water. Nitrogen adsorption-desorption isotherms showed that all the as-prepared microspheres had relatively high specific surface areas of about 50 m2 g-1. The 1 ?m sized TiO2 nanorod microspheres were fabricated as a scattering overlayer in DSSCs, leading to a remarkable improvement in the power conversion efficiency: 8.22% of the bi-layer DSSCs versus 7.00% for the reference cell made of a single-layer film prepared from nanocrystalline TiO2. Such improvement was mainly attributed to the enhanced light harvesting and dye loading brought by the effective scattering centers. Electronic supplementary information (ESI) available. See DOI: 10.1039/c3nr04462a

Rui, Yichuan; Li, Yaogang; Zhang, Qinghong; Wang, Hongzhi

2013-11-01

265

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

E-print Network

Europium-Doped TiO2 Hollow Nanoshells: Two-Photon Imaging of Cell Binding Sergio Sandoval,,,§ Jian method to fabricate luminescent monodisperse 200 nm europium-doped hollow TiO2 nanoshell (NS) particles-functionalized polystyrene beads were used as templates, and the porous walls of europium-doped titania nanoshells were

Kummel, Andrew C.

266

Solid-state dye-sensitized TiO(2) solar cells based on a sensitizer covalently wired to a hole conducting polymer.  

PubMed

We report on the molecular wiring efficiency of a ruthenium polypyridine complex acting as a sensitizer connected to a poly(3-hexyl)thiophene chain acting as hole transporting material. We have developed an efficient synthetic strategy to covalently connect via an ethanyl spacer a regioregular poly(3-hexyl)thiophene chain to a ruthenium complex. Solid-state dye-sensitized solar cells were prepared either with the latter system or with a similar ruthenium sensitizer but lacking the polymer chain (reference system). The comparison of the photocurrent-photovoltage characteristics of the cells recorded under AM1.5 indicates a two fold improvement of the overall photoconversion efficiencies when the sensitizer is grafted to the hole transporting material (eta = 0.27%) relative to the reference system (eta = 0.13%). The higher photovoltaic performance can be attributed to the better diffusion-like propagation of the holes from the sensitizer to the counter electrode through the covalently linked polythiophene chain. PMID:18597026

Houarner-Rassin, Coralie; Blart, Errol; Buvat, Pierrick; Odobel, Fabrice

2008-07-01

267

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

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

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

2014-01-01

268

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

NASA Astrophysics Data System (ADS)

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

2014-07-01

269

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

270

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

271

The induction of maturation on dendritic cells by TiO2 and Fe(3)O(4)@TiO(2) nanoparticles via NF-?B signaling pathway.  

PubMed

Nanomaterials are increasingly used in many fields, including drug vectors and vaccine formulation. In this study, nano-TiO(2) and magnetic Fe(3)O(4)@TiO(2) 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-TiO(2) and Fe(3)O(4)@TiO(2) were prepared with diameters of 82nm and 63nm, and zeta potentials of 41.5mV and 30.2mV, respectively. The magnetic property of Fe(3)O(4)@TiO(2) 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 Fe(3)O(4)@TiO(2)caused an increased expression of TNF-?, CD86 and CD80, and besides, Fe(3)O(4)@TiO(2)showed a certain up-regulation on MHC-II. The cellular uptake of Ovalbumin on BMDCs could be strongly improved by nano-TiO2 and Fe(3)O(4)@TiO(2)as detected via flow cytometer and confocal observation. Further investigation revealed that nano-TiO(2) and Fe(3)O(4)@TiO(2)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-TiO(2) and Fe(3)O(4)@TiO(2)may function as a useful vector to promote vaccine delivery in immune cells, and Fe(3)O(4)@TiO(2)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

272

Solar-induced self-assembly of TiO2-beta-cyclodextrin-MWCNT composite wires.  

PubMed

Wire-like TiO2-beta-cyclodextrin-MWCNT composites have been successfully fabricated through a solar-induced self-assembly process. The wires were stable for more than several months both in water and under air in dry conditions. The composites were characterized in detail by scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectra, Raman spectra and Raman mapping. The results revealed that the wires with a mean diameter of 1 microm were uniform. MWCNT and beta-cyclodextrin can interact with each other, which was confirmed in our previous research, meanwhile, monodisperse TiO2 nanoparticles can also associate with beta-cyclodextrin. Thus, beta-cyclodextrin molecules acted as linkers between MWCNT and monodisperse TiO2 nanoparticles. A reasonable mechanism was also proposed to explain the formation of this wire. Furthermore, the dye-sensitized solar cells were assembled with a sandwich-structured electrode containing the wires and they exhibited an enhanced power conversion efficiency. This may be attributable to the compact composite-structure of the wires and the unique electronic properties of MWCNT, which favor the transportation of photogenerated electrons. PMID:19290342

Zhou, Wei; Pan, Kai; Zhang, Lili; Tian, Chungui; Fu, Honggang

2009-03-21

273

Homogeneous Photosensitization of Complex TiO2 Nanostructures for Efficient Solar Energy Conversion  

PubMed Central

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

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

2012-01-01

274

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

NASA Astrophysics Data System (ADS)

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

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

2014-08-01

275

UV and Solar TiO2 Photocatalysis of Brevetoxins (PbTxs)  

PubMed Central

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

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

2012-01-01

276

UV and solar TiO(2) photocatalysis of brevetoxins (PbTxs).  

PubMed

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. TiO(2) photocatalysis under 350 nm and solar irradiation leads to significant degradation of PbTxs via first order kinetics. ELISA results demonstrate TiO(2) 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 TiO(2) photocatalysis of PbTxs. Our results indicate TiO(2) photocatalysis may be applicable for the degradation of PbTxs. PMID:19931554

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

2010-05-01

277

DNA can sediment TiO2 particles and decrease the uptake potential by mammalian cells.  

PubMed

Titanium dioxide (TiO(2)) is an important material used in a broad range of industries. As TiO(2) particles used in industries have recently become smaller as technology develops, problems specific to small size are increasing. One such problem is the difficulty of recovering TiO(2) particles suspended in solution. Particles not recovered during their manufacture would be released in the environment and might be taken up by living organisms, leading to "small-size specific toxicity", which has recently become a concern in numerous industries. To prevent environmental release of small-size TiO(2), separation and complete recovery of the particles are important. In this study, we showed that DNA could be used to separate TiO(2) particles (60-500 nm) from an aqueous solution. Although TiO(2) particles (20 mg/10 ml) were kept in suspension in a standing solution for 72 h, addition of small amounts of DNA (25-100 microg/10 ml) completely sedimented all particles within 4 h. Analysis with transmission electron microscopy suggested that the enhanced sedimentation with DNA was due to the formation of aggregates of TiO(2) particles with DNA. Conveniently, DNA-treated TiO(2) particles had difficulty translocating into human cell lines (keratinocytes and skin fibroblasts), suggesting that "small-size specific toxicity" can be prevented. DNA is a useful tool for separating TiO(2) particles which would prevent "small-size specific toxicity" by allowing quick and complete recovery and suppression of uptake by living organisms. PMID:19150108

Toyooka, Tatsushi; Amano, Takeharu; Suzuki, Hiroshi; Ibuki, Yuko

2009-03-15

278

Investigation of a broadband TiO 2\\/SiO 2 optical thin-film filter for hybrid solar power systems  

Microsoft Academic Search

Using the technology of spectral selectivity to integrate different solar power generators in a hybrid system is a feasible way to improve the optical-electric efficiency. This paper presents an 82-layer broadband optical interference thin-film filter matching with crystalline silicon photovoltaic cells, which using TiO2 and SiO2 as fabrication materials and can be used in hybrid solar power systems like photovoltaic–thermoelectric

Chunhui Shou; Zhongyang Luo; Tao Wang; Weidong Shen; Gary Rosengarten; Wei Wei; Cheng Wang; Mingjiang Ni; Kefa Cen

2012-01-01

279

Morphological alterations of T24 cells on flat and nanotubular TiO2 surfaces  

PubMed Central

Aim To investigate morphological alterations of malignant cancer cells (T24) of urothelial origin seeded on flat titanium (Ti) and nanotubular titanium dioxide (TiO2) nanostructures. Methods Using anodization method, TiO2 surfaces composed of vertically aligned nanotubes of 50-100 nm diameters were produced. The flat Ti surface was used as a reference. The alteration in the morphology of cancer cells was evaluated using scanning electron microscopy (SEM). A computational model, based on the theory of membrane elasticity, was constructed to shed light on the biophysical mechanisms responsible for the observed changes in the contact area of adhesion. Results Large diameter TiO2 nanotubes exhibited a significantly smaller contact area of adhesion (P?cell spreading on the large diameter TiO2 nanotubular surface, thus explaining the small contact area. Conclusion The reduction in the cell contact area in the case of large diameter TiO2 nanotube surface, which does not enable formation of the large enough number of the focal adhesion points, prevents spreading of urothelial cells. PMID:23275323

Imani, Roghayeh; Kabaso, Doron; Erdani Kreft, Mateja; Gongadze, Ekaterina; Peni?, Samo; Elerši?, Kristina; Kos, Andrej; Verani?, Peter; Zorec, Robert; Igli?, Aleš

2012-01-01

280

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

281

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

NASA Astrophysics Data System (ADS)

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

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

2010-01-01

282

Genome wide identification and expression profile in epithelial cells exposed to TiO2 particles.  

PubMed

Environmental particles are believed to provoke airway inflammation in susceptible individuals by stimulating epithelial cells to release mediators that exacerbate lung diseases. Here, we sought to identify genes expressed throughout the genome by epithelial cells stimulated with TiO2 particles. A human bronchial epithelial cell line, BEAS-2B, was stimulated with or without 40 µg TiO2 for 2 h. RNA was purified from cells and subjected to microarray analysis. Genes exhibiting more than a twofold change in RNA expression were selected. Candidate genes were then analyzed using bioinformatics tools, including pathway, ontology, and network analyses. ITGAV mRNA expression levels were measured in BEAS-2B cells using real-time polymerase chain reaction. Among 37,803 genes, 92 genes displayed more than a twofold change in mRNA levels according to the microarray analysis; 87 genes were upregulated while five genes were downregulated. The 92 genes were classified based on functional annotation using a protein information resource database search for biological processes and a pathway search using the KEGG pathway database. These genes are related to macromolecule biosynthesis, metabolic processes and, in particular, RNA metabolism. When genes with more than a threefold change were analyzed, KIF11, ITGAV, SEMA3C, IBTK, and DEK were selected as candidate genes induced by TiO2 -stimulated BEAS-2B cells. To validate these results, BEAS-2B cells stimulated with 40 µg TiO2 expressed threefold higher ITGAV mRNA levels compared to those without TiO2 particle stimulation. We conclude that KIF11, ITGAV, SEMA3C, IBTK, and DEK are candidate genes expressed by epithelial cells when stimulated with TiO2 particles. © 2013 Wiley Periodicals, Inc. Environ Toxicol 30: 293-300, 2015. PMID:24023007

Kim, Tae-Hoon; Shin, Seung-Woo; Park, Jong-Sook; Park, Choon-Sik

2015-03-01

283

Improved Performance of Dye-Sensitized Solar Cells Fabricated from a Coumarin NKX-2700 Dye-Sensitized TiO2/MgO Core-Shell Photoanode with an HfO2 Blocking Layer and a Quasi-Solid-State Electrolyte  

NASA Astrophysics Data System (ADS)

Dye sensitized solar cells (DSSC) were fabricated from a coumarin NKX-2700 dye-sensitized core-shell photoanode and a quasi-solid-state electrolyte, sandwiched together, with a cobalt sulfide-coated counter electrode. The core-shell photoanode consisted of a composite mixture of 90% TiO2 nanoparticles and 10% TiO2 nanowires (TNPW) as core layer and MgO nanoparticles (MNP) as shell layer. Hafnium oxide (HfO2) was applied to the core-shell photoanode film as a blocking layer. TiO2 nanoparticles, TiO2 nanowires, and TNPW/MNP were characterized by x-ray diffractometry, scanning electron microscopy, and transmission electron microscopy. It was apparent from the UV-visible spectrum of the sensitizing dye coumarin NKX-2700 that its absorption was maximum at 525 nm. Power conversion efficiency (PCE) was greater for DSSC-1, fabricated with a core-shell TNPW/MNP/HfO2 photoanode, than for the other DSSC; its photovoltaic properties were: short circuit photocurrent J sc = 19 mA/cm2, open circuit voltage ( V oc) = 720 mV, fill factor ( FF) = 66%, and PCE ( ?) = 9.02%. The charge-transport and charge-recombination behavior of the DSSC were investigated by electrochemical impedance spectroscopy; the results showed that the composite core-shell film resulted in the lowest charge-transfer resistance ( R CE) and the longest electron lifetime ( ? eff). Hence, the improved performance of DSSC-1 could be ascribed to the core-shell photoanode with blocking layer, which increased electron transport and suppressed recombination of charge carriers at the photoanode/dye/electrolyte interface.

Maheswari, D.; Venkatachalam, P.

2015-03-01

284

Detecting HER2 on cancer cells by TiO2 spheres Mie scattering.  

PubMed

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

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

2009-09-15

285

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

286

TiO2 nanoparticles and bulk material stimulate human peripheral blood mononuclear cells?  

PubMed Central

Nanomaterials are increasingly produced and used throughout recent years. Consequently the probability of exposure to nanoparticles has risen. Because of their small 1–100 nm size, the physicochemical properties of nanomaterials may differ from standard bulk materials and may pose a threat to human health. Only little is known about the effects of nanoparticles on the human immune system. In this study, we investigated the effects of TiO2 nanoparticles and bulk material in the in vitro model of human peripheral blood mononuclear cells (PBMC) and cytokine-induced neopterin formation and tryptophan breakdown was monitored. Both biochemical processes are closely related to the course of diseases like infections, atherogenesis and neurodegeneration. OCTi60 (25 nm diameter) TiO2 nanoparticles and bulk material increased neopterin production in unstimulated PBMC and stimulated cells significantly, the effects were stronger for OCTi60 compared to bulk material, while P25 TiO2 (25 nm diameter) nanoparticles had only little influence. No effect of TiO2 nanoparticles on tryptophan breakdown was detected in unstimulated cells, whereas in stimulated cells, IDO activity and IFN-? production were suppressed but only at the highest concentrations tested. Because neopterin was stimulated and tryptophan breakdown was suppressed in parallel, data suggests that the total effect of particles would be strongly pro-inflammatory. PMID:24361406

Becker, Kathrin; Schroecksnadel, Sebastian; Geisler, Simon; Carriere, Marie; Gostner, Johanna M.; Schennach, Harald; Herlin, Nathalie; Fuchs, Dietmar

2014-01-01

287

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

288

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

NASA Astrophysics Data System (ADS)

Bandgap engineering of a photonic crystal is highly desirable for photon management in photonic sensors and devices. Aperiodic photonic crystals (APCs) can provide unprecedented opportunities for much more versatile photon management, due to increased degrees of freedom in the design and the unique properties brought about by the aperiodic structures as compared to their periodic counterparts. However, many efforts still remain on conceptual approaches, practical achievements in APCs are rarely reported due to the difficulties in fabrication. Here, we report a simple but highly controllable current-pulse anodization process to design and fabricate TiO2 nanotube APCs. By coupling an APC into the photoanode of a dye-sensitized solar cell, we demonstrate the concept of using APC to achieve nearly full-visible-spectrum light harvesting, as evidenced by both experimental and simulated results. It is anticipated that this work will lead to more fruitful practical applications of APCs in high-efficiency photovoltaics, sensors and optoelectronic devices.

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

2014-09-01

289

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

PubMed

An improvement in the power conversion efficiency (PCE) of the inverted organic solar cell (ITO/nc-TiO2/P3HT:PCBM/PEDOT:PSS/Ag) is realized by depositing CdS quantum dots (QDs) on a nanocrystalline TiO2 (nc-TiO2) film as a light absorption material and an electron-selective material. The CdS QDs were deposited via a chemical bath deposition (CBD) method. Our results show that the best PCE of 3.37% for the ITO/nc-TiO2/CdS/P3HT:PCBM/PEDOT:PSS/Ag cell is about 1.13 times that (2.98%) of the cell without CdS QDs (i.e., ITO/nc-TiO2/P3HT:PCBM/PEDOT:PSS/Ag). The improved PCE can be mainly attributed to the increased light absorption and the reduced recombination of charge carriers from the TiO2 to the P3HT:PCBM film due to the introduced CdS QDs. PMID:24172258

Chen, Chong; Li, Fumin

2013-01-01

290

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

PubMed Central

An improvement in the power conversion efficiency (PCE) of the inverted organic solar cell (ITO/nc-TiO2/P3HT:PCBM/PEDOT:PSS/Ag) is realized by depositing CdS quantum dots (QDs) on a nanocrystalline TiO2 (nc-TiO2) film as a light absorption material and an electron-selective material. The CdS QDs were deposited via a chemical bath deposition (CBD) method. Our results show that the best PCE of 3.37% for the ITO/nc-TiO2/CdS/P3HT:PCBM/PEDOT:PSS/Ag cell is about 1.13 times that (2.98%) of the cell without CdS QDs (i.e., ITO/nc-TiO2/P3HT:PCBM/PEDOT:PSS/Ag). The improved PCE can be mainly attributed to the increased light absorption and the reduced recombination of charge carriers from the TiO2 to the P3HT:PCBM film due to the introduced CdS QDs. PMID:24172258

2013-01-01

291

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

NASA Astrophysics Data System (ADS)

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

Chen, Chong; Li, Fumin

2013-10-01

292

Remediation of 17-?-ethinylestradiol aqueous solution by photocatalysis and electrochemically-assisted photocatalysis using TiO2 and TiO2/WO3 electrodes irradiated by a solar simulator.  

PubMed

TiO2 and TiO2/WO3 electrodes, irradiated by a solar simulator in configurations for heterogeneous photocatalysis (HP) and electrochemically-assisted HP (EHP), were used to remediate aqueous solutions containing 10 mg L(-1) (34 ?mol L(-1)) of 17-?-ethinylestradiol (EE2), active component of most oral contraceptives. The photocatalysts consisted of 4.5 ?m thick porous films of TiO2 and TiO2/WO3 (molar ratio W/Ti of 12%) deposited on transparent electrodes from aqueous suspensions of TiO2 particles and WO3 precursors, followed by thermal treatment at 450 (°)C. First, an energy diagram was organized with photoelectrochemical and UV-Vis absorption spectroscopy data and revealed that EE2 could be directly oxidized by the photogenerated holes at the semiconductor surfaces, considering the relative HOMO level for EE2 and the semiconductor valence band edges. Also, for the irradiated hybrid photocatalyst, electrons in TiO2 should be transferred to WO3 conduction band, while holes move toward TiO2 valence band, improving charge separation. The remediated EE2 solutions were analyzed by fluorescence, HPLC and total organic carbon measurements. As expected from the energy diagram, both photocatalysts promoted the EE2 oxidation in HP configuration; after 4 h, the EE2 concentration decayed to 6.2 mg L(-1) (35% of EE2 removal) with irradiated TiO2 while TiO2/WO3 electrode resulted in 45% EE2 removal. A higher performance was achieved in EHP systems, when a Pt wire was introduced as a counter-electrode and the photoelectrodes were biased at +0.7 V; then, the EE2 removal corresponded to 48 and 54% for the TiO2 and TiO2/WO3, respectively. The hybrid TiO2/WO3, when compared to TiO2 electrode, exhibited enhanced sunlight harvesting and improved separation of photogenerated charge carriers, resulting in higher performance for removing this contaminant of emerging concern from aqueous solution. PMID:25238917

Oliveira, Haroldo G; Ferreira, Leticia H; Bertazzoli, Rodnei; Longo, Claudia

2015-04-01

293

Effects of TiO2 and Co3O4 Nanoparticles on Circulating Angiogenic Cells  

PubMed Central

Background and Aim Sparse evidence suggests a possible link between exposure to airborne nanoparticles (NPs) and cardiovascular (CV) risk, perhaps through mechanisms involving oxidative stress and inflammation. We assessed the effects of TiO2 and Co3O4 NPs in human circulating angiogenic cells (CACs), which take part in vascular endothelium repair/replacement. Methods CACs were isolated from healthy donors’ buffy coats after culturing lymphomonocytes on fibronectin-coated dishes in endothelial medium for 7 days. CACs were pre-incubated with increasing concentration of TiO2 and Co3O4 (from 1 to 100 ?g/ml) to test the effects of NP – characterized by Transmission Electron Microscopy – on CAC viability, apoptosis (caspase 3/7 activation), function (fibronectin adhesion assay), oxidative stress and inflammatory cytokine gene expression. Results Neither oxidative stress nor cell death were associated with exposure to TiO2 NP (except at the highest concentration tested), which, however, induced a higher pro-inflammatory effect compared to Co3O4 NPs (p<0.01). Exposure to Co3O4 NPs significantly reduced cell viability (p<0.01) and increased caspase activity (p<0.01), lipid peroxidation end-products (p<0.05) and pro-inflammatory cytokine gene expression (p<0.05 or lower). Notably, CAC functional activity was impaired after exposure to both TiO2 (p<0.05 or lower) and Co3O4 (p<0.01) NPs. Conclusions In vitro exposure to TiO2 and Co3O4 NPs exerts detrimental effects on CAC viability and function, possibly mediated by accelerated apoptosis, increased oxidant stress (Co3O4 NPs only) and enhancement of inflammatory pathways (both TiO2 and Co3O4 NPs). Such adverse effects may be relevant for a potential role of exposure to TiO2 and Co3O4 NPs in enhancing CV risk in humans. PMID:25803285

Spigoni, Valentina; Cito, Monia; Alinovi, Rossella; Pinelli, Silvana; Passeri, Giovanni; Zavaroni, Ivana; Goldoni, Matteo; Campanini, Marco; Aliatis, Irene; Mutti, Antonio

2015-01-01

294

TiO(2) nanoparticles induce oxidative DNA damage and apoptosis in human liver cells.  

PubMed

Titanium dioxide nanoparticles (TiO(2) NPs), widely used in consumer products, paints, pharmaceutical preparations and so on, have been shown to induce cytotoxicity, genotoxicity and carcinogenic responses in vitro and in vivo. The present study revealed that TiO(2) NPs induce significant (p < 0.05) oxidative DNA damage by the Fpg-Comet assay even at 1 µg/ml concentration. A corresponding increase in the micronucleus frequency was also observed. This could be attributed to the reduced glutathione levels with concomitant increase in lipid peroxidation and reactive oxygen species generation. Furthermore, immunoblot analysis revealed an increased expression of p53, BAX, Cyto-c, Apaf-1, caspase-9 and caspase-3 and decreased the level of Bcl-2 thereby indicating that apoptosis induced by TiO(2) NPs occurs via the caspase-dependent pathway. This study systematically shows that TiO(2) NPs induce DNA damage and cause apoptosis in HepG2 cells even at very low concentrations. Hence the use of such nanoparticles should be carefully monitored. PMID:22047016

Shukla, Ritesh K; Kumar, Ashutosh; Gurbani, Deepak; Pandey, Alok K; Singh, Shashi; Dhawan, Alok

2013-02-01

295

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

Microsoft Academic Search

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

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

2003-01-01

296

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

PubMed

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

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

2009-10-01

297

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

PubMed Central

To study the effect of nanoscale titanium dioxide (TiO2) on cell responses, we synthesized four modifications of the TiO2 (amorphous, anatase, brookite, and rutile) capable of keeping their physicochemical characteristics in a cell culture medium. The modifications of nanoscale TiO2 were obtained by hydrolysis of TiCl4 and Ti(i-OC3H7)4 (TIP) upon variation of the synthesis conditions; their textural, morphological, structural, and dispersion characteristics were examined by a set of physicochemical methods: XRD, BET, SAXS, DLS, AFM, SEM, and HR-TEM. The effect of synthesis conditions (nature of precursor, pH, temperature, and addition of a complexing agent) on the structural-dispersion properties of TiO2 nanoparticles was studied. The hydrolysis methods providing the preparation of amorphous, anatase, brookite, and rutile modifications of TiO2 nanoparticles 3–5?nm in size were selected. Examination of different forms of TiO2 nanoparticles interaction with MDCK cells by transmission electron microscopy of ultrathin sections revealed different cell responses after treatment with different crystalline modifications and amorphous form of TiO2. The obtained results allowed us to conclude that direct contact of the nanoparticles with cell plasma membrane is the primary and critical step of their interaction and defines a subsequent response of the cell. PMID:22623903

Ismagilov, Z. R.; Shikina, N. V.; Mazurkova, N. A.; Tsikoza, L. T.; Tuzikov, F. V.; Ushakov, V. A.; Ishchenko, A. V.; Rudina, N. A.; Korneev, D. V.; Ryabchikova, E. I.

2012-01-01

298

Microstructured extremely thin absorber solar cells  

Microsoft Academic Search

In this paper we present the realization of extremely thin absorber (ETA) solar cells employing conductive glass substrates functionalized with TiO2 microstructures produced by embossing. Nanocrystalline or compact TiO2 films on Indium doped tin oxide (ITO) glass substrates were embossed by pressing a silicon stamp containing a ?m size raised grid structure into the TiO2 by use of a hydraulic

Matteo Biancardo; Frederik C. Krebs

2007-01-01

299

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

300

Disorder engineering of undoped TiO2 nanotube arrays for highly efficient solar-driven oxygen evolution.  

PubMed

The trade-off between performance and complexity of the device manufacturing process should be balanced to enable the economic harvest of solar energy. Here, we demonstrate a conceptual, yet practical and well-regulated strategy to achieve efficient solar photocatalytic activity in TiO2 through controlled phase transformation and disorder engineering in the surface layers of TiO2 nanotubes. This approach enabled us to fine-tune the bandgap structure of undoped TiO2 according to our needs while simultaneously obtaining robust separation of photo-excited charge carriers. Introduction of specific surface defects also assisted in utilization of the visible part of sunlight to split water molecules for the production of oxygen. The strategy proposed here can serve as a guideline to overcome the practical limitation in the realization of efficient, non-toxic, chemically stable photoelectrochemical systems with high catalytic activity at neutral pH under visible illumination conditions. We also successfully incorporated TiO2 nanotube arrays (TNTAs) with free-based porphyrin affording a pathway with an overall 140% enhanced efficiency, an oxygen evolution rate of 436 ?L h(-1) and faradic efficiencies over 100%. PMID:25623280

Salari, M; Aboutalebi, S H; Aghassi, A; Wagner, P; Mozer, A J; Wallace, G G

2015-02-28

301

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

PubMed

The objective of this work was to evaluate the efficiency of a solar TiO2-assisted photocatalytic process on amoxicillin (AMX) degradation, an antibiotic widely used in human and veterinary medicine. Firstly, solar photolysis of AMX was compared with solar photocatalysis in a compound parabolic collectors pilot scale photoreactor to assess the amount of accumulated UV energy in the system (Q UV) necessary to remove 20 mg L(-1) AMX from aqueous solution and mineralize the intermediary by-products. Another experiment was also carried out to accurately follow the antibacterial activity against Escherichia coli DSM 1103 and Staphylococcus aureus DSM 1104 and mineralization of AMX by tracing the contents of dissolved organic carbon (DOC), low molecular weight carboxylate anions, and inorganic anions. Finally, the influence of individual inorganic ions on AMX photocatalytic degradation efficiency and the involvement of some reactive oxygen species were also assessed. Photolysis was shown to be completely ineffective, while only 3.1 kJUV?L(-1) was sufficient to fully degrade 20 mg L(-1) AMX and remove 61% of initial DOC content in the presence of the photocatalyst and sunlight. In the experiment with an initial AMX concentration of 40 mg L(-1), antibacterial activity of the solution was considerably reduced after elimination of AMX to levels below the respective detection limit. After 11.7 kJUV?L(-1), DOC decreased by 71%; 30% of the AMX nitrogen was converted into ammonium and all sulfur compounds were converted into sulfate. A large percentage of the remaining DOC was in the form of low molecular weight carboxylic acids. Presence of phosphate ions promoted the removal of AMX from solution, while no sizeable effects on the kinetics were found for other inorganic ions. Although the AMX degradation was mainly attributed to hydroxyl radicals, singlet oxygen also plays an important role in AMX self-photosensitization under UV/visible solar light. PMID:23900954

Pereira, João H O S; Reis, Ana C; Nunes, Olga C; Borges, Maria T; Vilar, Vítor J P; Boaventura, Rui A R

2014-01-01

302

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

303

Cobalt phosphate modified TiO2 nanowire arrays as co-catalysts for solar water splitting.  

PubMed

Cobalt phosphate (Co-Pi) is photo-electrodeposited on TiO2 nanowire arrays in Co(2+) containing phosphate buffer. The resulting composite photoanode shows a generally enhanced photocurrent near the flat band potential region, and represents a 2.3 times improved photoconversion efficiency compared to that of pristine TiO2 in a neutral electrolyte. A negative effect on the photocurrent generation is also observed when loading TiO2 with a relatively thick Co-Pi layer, which is demonstrated to be due to the poor photohole transfer kinetics in the Co-Pi layer. Moreover, we find that Co-Pi can facilitate the photoelectrochemical performance of TiO2 over a wide pH range from 1-14. This improved activity is studied in detail by optical and electrochemical analyses. It is suggested that the mechanism of the overpotential-demanding water oxidation reaction is changed to a facile pathway by the Co-based electrocatalyst. At the same time, the more significant band bending is induced by the Co-Pi catalyst decreasing the charge recombination. This work provides a feasible route to reduce the external power needed to drive water splitting by coupling an electrocatalyst with a photocatalyst, as well as mechanistic insights important for other Co-Pi modified photoelectrodes for solar-driven water splitting. PMID:25804292

Ai, Guanjie; Mo, Rong; Li, Hongxing; Zhong, Jianxin

2015-04-01

304

Fabrication and characterization of photovoltaic devices based on perovskite compounds with TiO2 nanoparticles  

NASA Astrophysics Data System (ADS)

Perovskite-type photovoltaic devices were fabricated by a spin-coating method using a mixture solution. The compact and meso-porous TiO2 of the solar cells were fabricated from TiO2 nanoparticles and sol, and the photovoltaic properties and microstructures were characterized. The conversion efficiencies were improved by the combination of TiO2 nanoparticles and sol. Current density was also improved by increasing numbers of spin-coatings of meso-porous TiO2. Thick meso-porous TiO2 layers would assist the construction of perovskite layers and block of the leak current.

Kanayama, Masato; Oku, Takeo; Suzuki, Atsushi; Yamada, Masahiro; Fukunishi, Sakiko; Kohno, Kazufumi; Sakamoto, Hiroki

2015-02-01

305

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

PubMed Central

Bandgap engineering of a photonic crystal is highly desirable for photon management in photonic sensors and devices. Aperiodic photonic crystals (APCs) can provide unprecedented opportunities for much more versatile photon management, due to increased degrees of freedom in the design and the unique properties brought about by the aperiodic structures as compared to their periodic counterparts. However, many efforts still remain on conceptual approaches, practical achievements in APCs are rarely reported due to the difficulties in fabrication. Here, we report a simple but highly controllable current-pulse anodization process to design and fabricate TiO2 nanotube APCs. By coupling an APC into the photoanode of a dye-sensitized solar cell, we demonstrate the concept of using APC to achieve nearly full-visible-spectrum light harvesting, as evidenced by both experimental and simulated results. It is anticipated that this work will lead to more fruitful practical applications of APCs in high-efficiency photovoltaics, sensors and optoelectronic devices. PMID:25245854

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

2014-01-01

306

TiO2 nanoparticles induce DNA double strand breaks and cell cycle arrest in human alveolar cells.  

PubMed

TiO2 nanoparticles (NPs) have the second highest global annual production (?3000 tons) among the metal-containing NPs. These NPs are used as photocatalysts for bacterial disinfection, and in various other consumer products including sunscreen, food packaging, therapeutics, biosensors, surface cleaning agents, and others. Humans are exposed to these NPs during synthesis (laboratory), manufacture (industry), and use (consumer products, devices, medicines, etc.), as well as through environmental exposures (disposal). Hence, there is great concern regarding the health effects caused by exposure to NPs and, in particular, to TiO2 NPs. In the present study, the genotoxic potential of TiO2 NPs in A549 cells was examined, focusing on their potential to induce ROS, different types of DNA damage, and cell cycle arrest. We show that TiO2 NPs can induce DNA damage and a corresponding increase in micronucleus frequency, as evident from the comet and cytokinesis-block micronucleus assays. We demonstrate that DNA damage may be attributed to increased oxidative stress and ROS generation. Furthermore, genomic and proteomic analyses showed increased expression of ATM, P53, and CdC-2 and decreased expression of ATR, H2AX, and Cyclin B1 in A549 cells, suggesting induction of DNA double strand breaks. The occurrence of double strand breaks was correlated with cell cycle arrest in G2/M phase. Overall, the results indicate the potential for genotoxicity following exposure to these TiO2 NPs, suggesting that use should be carefully monitored. Environ. Mol. Mutagen. 56:204-217, 2015. © 2014 Wiley Periodicals, Inc. PMID:25524809

Kansara, Krupa; Patel, Pal; Shah, Darshini; Shukla, Ritesh K; Singh, Sanjay; Kumar, Ashutosh; Dhawan, Alok

2015-03-01

307

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

308

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

309

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

PubMed

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

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

2012-02-01

310

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

PubMed Central

A simple scalable method to fabricate luminescent monodisperse 200 nm europium doped hollow TiO2 nanoshell particles is reported. Fluorophore reporter, Eu3+ ions, are incorporated directly in the NS matrix, leaving the surface free for functionalization and the core free for payload encapsulation. Amine functionalized polystyrene beads were used as templates, and the porous walls of europium doped titania nanoshells were synthesized using titanium(IV) t-butoxide and europium(III) nitrate as reactants. X-ray diffraction analysis identified anatase as the predominant titania phase of the rigid nanoshell wall structure, and photoluminescence spectra showed that the Eu(III) doped TiO2 nanoshells exhibited a red emission at 617 nm due to an atomic f-f transition. Nanoshell interactions with HeLa cervical cancer cells in vitro were visualized using two-photon microscopy of the Eu(III) emission, and studied using a luminescence ratio analysis to assess nanoshell adhesion and endocytosis. PMID:23185106

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

2012-01-01

311

Structure, Synthesis, and Applications of TiO2 Nanobelts.  

PubMed

TiO2 semiconductor nanobelts have unique structural and functional properties, which lead to great potential in many fields, including photovoltaics, photocatalysis, energy storage, gas sensors, biosensors, and even biomaterials. A review of synthetic methods, properties, surface modification, and applications of TiO2 nanobelts is presented here. The structural features and basic properties of TiO2 nanobelts are systematically discussed, with the many applications of TiO2 nanobelts in the fields of photocatalysis, solar cells, gas sensors, biosensors, and lithium-ion batteries then introduced. Research efforts that aim to overcome the intrinsic drawbacks of TiO2 nanobelts are also highlighted. These efforts are focused on the rational design and modification of TiO2 nanobelts by doping with heteroatoms and/or forming surface heterostructures, to improve their desirable properties. Subsequently, the various types of surface heterostructures obtained by coupling TiO2 nanobelts with metal and metal oxide nanoparticles, chalcogenides, and conducting polymers are described. Further, the charge separation and electron transfer at the interfaces of these heterostructures are also discussed. These properties are related to improved sensitivity and selectivity for specific gases and biomolecules, as well as enhanced UV and visible light photocatalytic properties. The progress in developments of near-infrared-active photocatalysts based on TiO2 nanobelts is also highlighted. Finally, an outline of important directions of future research into the synthesis, modification, and applications of this unique material is given. PMID:25800706

Zhao, Zhenhuan; Tian, Jian; Sang, Yuanhua; Cabot, Andreu; Liu, Hong

2015-04-01

312

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. PMID:20480003

Wei, Di

2010-01-01

313

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

NASA Astrophysics Data System (ADS)

We investigated the effects of two types of TiO2 nanoparticles (<25 nm anatase, TiO2-An; <100 nm rutile, TiO2-Ru) on cellular antioxidant defense in HepG2 cells. We previously showed that in HepG2 cells, TiO2 nanoparticles are not toxic, although they induce oxidative DNA damage, production of intracellular reactive oxygen species, and up-regulation of mRNA expression of DNA-damage-responsive genes (p53, p21, gadd45? and mdm2). In the present study, we measured changes in mRNA expression of several antioxidant enzymes: catalase, superoxide dismutase, glutathione peroxidase, nitric oxide synthase, glutathione reductase and glutamate-cysteine ligase. As reduced glutathione has a central role in cellular antioxidant defense, we determined the effects of TiO2 nanoparticles on changes in the intracellular glutathione content. To confirm a role for glutathione in protection against TiO2-nanoparticle-induced DNA damage, we compared the extent of TiO2-nanoparticle-induced DNA damage in HepG2 cells that were glutathione depleted with buthionine-(S,R)-sulfoximine pretreatment and in nonglutathione-depleted cells. Our data show that both types of TiO2 nanoparticles up-regulate mRNA expression of oxidative-stress-related genes, with TiO2-Ru being a stronger inducer than TiO2-An. Both types of TiO2 nanoparticles also induce dose-dependent increases in intracellular glutathione levels, and in glutathione-depleted cells, TiO2-nanoparticle-induced DNA damage was significantly greater than in nonglutathione-depleted cells. Interestingly, the glutathione content and the extent of DNA damage were significantly higher in TiO2-An- than TiO2-Ru-exposed cells. Thus, we show that TiO2 nanoparticles cause activation of cellular antioxidant processes, and that intracellular glutathione has a critical role in defense against this TiO2-nanoparticle-induced DNA damage.

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

2011-07-01

314

Nanoscale TiO2 nanotubes govern the biological behavior of human glioma and osteosarcoma cells  

PubMed Central

Cells respond to their surroundings through an interactive adhesion process that has direct effects on cell proliferation and migration. This research was designed to investigate the effects of TiO2 nanotubes with different topographies and structures on the biological behavior of cultured cells. The results demonstrated that the nanotube diameter, rather than the crystalline structure of the coatings, was a major factor for the biological behavior of the cultured cells. The optimal diameter of the nanotubes was 20 nm for cell adhesion, migration, and proliferation in both glioma and osteosarcoma cells. The expression levels of vitronectin and phosphor-focal adhesion kinase were affected by the nanotube diameter; therefore, it is proposed that the responses of vitronectin and phosphor-focal adhesion kinase to the nanotube could modulate cell fate. In addition, the geometry and size of the nanotube coating could regulate the degree of expression of acetylated ?-tubulin, thus indirectly modulating cell migration behavior. Moreover, the expression levels of apoptosis-associated proteins were influenced by the topography. In conclusion, a nanotube diameter of 20 nm was the critical threshold that upregulated the expression level of Bcl-2 and obviously decreased the expression levels of Bax and caspase-3. This information will be useful for future biomedical and clinical applications.

Tian, Ang; Qin, Xiaofei; Wu, Anhua; Zhang, Hangzhou; Xu, Quan; Xing, Deguang; Yang, He; Qiu, Bo; Xue, Xiangxin; Zhang, Dongyong; Dong, Chenbo

2015-01-01

315

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

PubMed Central

We report a new semitransparent inverted polymer solar cell (PSC) with a structure of glass/FTO/nc-TiO2/P3HT:PCBM/MoO3/Ag/MoO3. Because high-temperature annealing which decreased the conductivity of indium tin oxide (ITO) must be handled in the process of preparation of nanocrystalline titanium oxide (nc-TiO2), we replace glass/ITO with a glass/fluorine-doped tin oxide (FTO) substrate to improve the device performance. The experimental results show that the replacing FTO substrate enhances light transmittance between 400 and 600 nm and does not change sheet resistance after annealing treatment. The dependence of device performances on resistivity, light transmittance, and thickness of the MoO3/Ag/MoO3 film was investigated. High power conversion efficiency (PCE) was achieved for FTO substrate inverted PSCs, which showed about 75% increase compared to our previously reported ITO substrate device at different thicknesses of the MoO3/Ag/MoO3 transparent electrode films illuminated from the FTO side (bottom side) and about 150% increase illuminated from the MoO3/Ag/MoO3 side (top side). PMID:25332693

2014-01-01

316

Induction of apoptosis associated with chromosomal DNA fragmentation and caspase-3 activation in leukemia L1210 cells by TiO2 nanoparticles.  

PubMed

We investigated the effects of nanosized TiO2 particles on the death of mouse leukemia L1210 cells. TiO2 particles suppressed proliferation and induced cell death, as measured by lactate dehydrogenase (LDH) release into the culture medium. Chromatin condensation, which is typical of the initiation of cell death, was observed in approximately 14% cells cultured with titanium dioxide (TiO2) particles for 12 h. Furthermore, giant DNA fragments of approximately 2 Mbp and high-molecular-weight DNA fragments between 100 kbp and 1 Mbp were observed in cells cultured for 18 h with TiO2 particles. These giant and high-molecular-weight DNA fragments were further degraded into smaller DNA fragments, appearing as DNA ladders. Corresponding to the generation of DNA fragments, caspase-3 activity increased in cells treated with TiO2 particles. TiO2 particle-induced LDH release was not inhibited by cytochalasin D, an inhibitor of endocytosis. These results suggest that nanosized TiO2 particles can induce apoptosis associated with DNA fragmentation and caspase-3 activation and that TiO2 particle-induced apoptosis is not caused by endocytosis but is associated with contact of the particles with the cell surface. PMID:23849803

Takaki, Keiko; Higuchi, Yoshihiro; Hashii, Minako; Ogino, Chiaki; Shimizu, Nobuaki

2014-01-01

317

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

PubMed

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

Ghosh, Manosij; Chakraborty, Anirban; Mukherjee, Anita

2013-10-01

318

Short communication Effect of vanadium redox species on photoelectrochemical behavior of TiO2  

E-print Network

Short communication Effect of vanadium redox species on photoelectrochemical behavior of TiO2 TiO2/WO3 Photoelectrochemical cell Vanadium redox Photocharge/discharge a b s t r a c by using a vanadium redox (VO2þ ) species. The goal is to explore regenerative solar energy storage using

Liu, Fuqiang

319

Exploring the Important Role of Nanocrystals Orientation in TiO2 Superstructure on Photocatalytic Performances.  

PubMed

Efficient charge separation has been widely accepted as one of the important factors responsible for the photocatalytic water splitting, organic oxidation, and solar cell, etc. TiO2 mesocrystal is a superstructure which could largely enhance charge separation, where TiO2 nanocrystals with parallel crystallographic alignment assemble in a form of oriented aggregation. Here, the intercrystal misorientation in TiO2 superstructure was first concerned and evaluated on the influence of photocatalytic efficiency. Our results showed that the intercrystal misorientation in TiO2 superstructures had a harmful effect on the charge separation efficiency. PMID:25738616

Chen, Feifei; Cao, Fenglei; Li, Hexing; Bian, Zhenfeng

2015-03-24

320

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

NASA Astrophysics Data System (ADS)

A viable option for recycling carbon dioxide is through the sunlight-powered photocatalytic conversion of CO2 and water vapor into hydrocarbon fuels over highly active nanocatalysts. With photocatalytic CO2 reduction sunlight, a renewable energy source as durable as the sun, is used to drive the catalytic reaction with the resultant fuel products compatible with the current hydrocarbon-based energy infrastructure. The use of co-catalyst (Cu, Pt)-sensitized TiO2 nanoparticle wafers in the photocatalytic conversion of CO2 and water vapor to hydrocarbon fuels, with optimal humidity levels and exposure times established. We also attempted to increase product formation by sputtering both co-catalysts on the nanoparticle wafer's surface, with the resulting product rates significantly higher than that of either the Cu or Pt coated samples. When the TiO2 nanoparticle wafers are used in a flow-through membrane implementation we find a significant increase in product rates of formation, including methane, hydrogen, and carbon monoxide. We believe that nanocatalyst-based flow-through membranes are a viable route for achieving large-scale and low cost photocatalytic solar fuel production.

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

2014-01-01

321

Influence of sintering temperature on energy conversion efficiency in dye-sensitized solar cell  

Microsoft Academic Search

The dye-sensitized nanocrystalline TiO2 film solar cells were fabricated here. The TiO2 electrodes were prepared by a sol-gel process and were sensitized by the nature dye extracted from a paper mulberry tree. When the sintering temperature of TiO2 films rises from 90 to 500 ?? , the energy conversion efficiency of the solar cell improves considerably and up to an

Di Yang; Ke Wang; Wen-Zhong Wang; Yi-Quan Wang; Gu-Ling Zhang; Wen-Liang Gao; Kai-Xiang Shen

2011-01-01

322

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

NASA Astrophysics Data System (ADS)

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

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

2011-03-01

323

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

NASA Astrophysics Data System (ADS)

To endow titanium (Ti) with antibacterial properties, different concentrations of zinc oxide (ZnO) nanoparticles were decorated on anodized titanium dioxide (TiO2) nanotubes by a simple hydrothermal treatment method. The particle sizes of ZnO, which were evenly distributed and tightly adherent to the walls of the Ti nanotubes, ranged from 20-50 nm. Results from this study showed that Zn was released from the TiO2 nanotubes in a constant, slow, and biologically inspired manner. Importantly, the results showed that the ZnO decorated TiO2 nanotubular samples inhibited Streptococcus mutants and Porphyromonas gingivalis growth compared to control unmodified Ti samples. Specifically, S. mutants and P. gingivalis growth were both reduced 45-85% on the ZnO decorated Ti samples compared to Ti controls after 7 days of culture. When examining the mechanism of action, it has been further found for the first time that the ZnO decorated Ti samples inhibited the expression of Streptococcus mutans bacterial adhesion genes. Lastly, the results showed that the same samples which decreased bacterial growth the most (0.015 M precursor Zn(NO3)2 samples) did not inhibit mesenchymal stem cell growth compared to Ti controls for up to 7 days. In summary, results from this study showed that compared to plain TiO2 nanotubes, TiO2 decorated with 0.015 M ZnO provided unprecedented antibacterial properties while maintaining the stem cell proliferation capacity necessary for enhancing the use of Ti in numerous medical applications, particularly in dentistry.

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

2014-07-01

324

Comparison of photocatalytic and transport properties of TiO2 and ZnO nanostructures for solar-driven water splitting.  

PubMed

Titanium dioxide (TiO2) and zinc oxide (ZnO) nanostructures have been widely used as photo-catalysts due to their low-cost, high surface area, robustness, abundance and non-toxicity. In this work, four TiO2 and ZnO-based nanostructures, i.e. TiO2 nanoparticles (TiO2 NPs), TiO2 nanotubes (TiO2 NTs), ZnO nanowires (ZnO NWs) and ZnO@TiO2 core-shell structures, specifically prepared with a fixed thickness of about 1.5 ?m, are compared for the solar-driven water splitting reaction, under AM1.5G simulated sunlight. Complete characterization of these photo-electrodes in their structural and photo-electrochemical properties was carried out. Both TiO2 NPs and NTs showed photo-current saturation reaching 0.02 and 0.12 mA cm(-2), respectively, for potential values of about 0.3 and 0.6 V vs. RHE. In contrast, the ZnO NWs and the ZnO@TiO2 core-shell samples evidence a linear increase of the photocurrent with the applied potential, reaching 0.45 and 0.63 mA cm(-2) at 1.7 V vs. RHE, respectively. However, under concentrated light conditions, the TiO2 NTs demonstrate a higher increase of the performance with respect to the ZnO@TiO2 core-shells. Such material-dependent behaviours are discussed in relation with the different charge transport mechanisms and interfacial reaction kinetics, which were investigated through electrochemical impedance spectroscopy. The role of key parameters such as electronic properties, specific surface area and photo-catalytic activity in the performance of these materials is discussed. Moreover, proper optimization strategies are analysed in view of increasing the efficiency of the best performing TiO2 and ZnO-based nanostructures, toward their practical application in a solar water splitting device. PMID:25715190

Hernández, Simelys; Hidalgo, Diana; Sacco, Adriano; Chiodoni, Angelica; Lamberti, Andrea; Cauda, Valentina; Tresso, Elena; Saracco, Guido

2015-03-11

325

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

Microsoft Academic Search

In this work, we report on the photo-catalytic properties of TiO2–ITO nanocomposite deposited on low cost conventional clay ceramic substrates. The nanocomposite was formed by spraying a solution prepared from the P25 TiO2 powder (Degussa) mixed with an organometallic paste of a dissolved combination of indium and tin. A TiO2–ITO powder-like nanocomposite was prepared for X-ray diffraction (XRD) and transmission

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

2010-01-01

326

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

Microsoft Academic Search

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

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

2008-01-01

327

Laser kinetic spectroscopy of the interfacial charge transfer between membrane cell walls of E. coli and TiO 2  

Microsoft Academic Search

This laser kinetics features of the electron decay of TiO2 in the presence of the Escherichia coli (E. coli) phosphatidyl-ethanolcholine (PE) and lipo-polysaccharides (LPS) cell wall components were are reported in this study. The interaction of the biomolecules with the photogenerated charge carriers was determined and the reaction rates were measured. The effect of the variation of ionic strength of

V. Nadtochenko; N. Denisov; O. Sarkisov; D. Gumy; C. Pulgarin; J. Kiwi

2006-01-01

328

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

PubMed

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

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

2012-07-01

329

The Osteogenic Properties of Multipotent Mesenchymal Stromal Cells in Cultures on TiO2 Sol-Gel-Derived Biomaterial  

PubMed Central

The biocompatibility of the bone implants is a crucial factor determining the successful tissue regeneration. The aim of this work was to compare cellular behavior and osteogenic properties of rat adipose-derived multipotent stromal cells (ASCs) and bone marrow multipotent stromal cells (BMSCs) cultured on metallic substrate covered with TiO2 sol-gel-derived nanolayer. The morphology, proliferation rate, and osteogenic differentiation potential of both ASCs and BMSCs propagated on the biomaterials were examined. The potential for osteogenic differentiation of ASCs and BMSCs was determined based on the presence of specific markers of osteogenesis, that is, alkaline phosphatase (ALP), osteopontin (OPN), and osteocalcin (OCL). Additionally, the concentration of calcium and phosphorus in extracellular matrix was determined using energy-dispersive X-ray spectroscopy (SEM-EDX). Obtained results showed that TiO2 layer influenced proliferation activity of ASCs, which manifested by shortening of population doubling time and increase of OPN secretion. However, characteristic features of cells morphology and growth pattern of cultures prompted us to conclude that ultrathin TiO2 layer might also enhance osteodifferentiation of BMSCs. Therefore in our opinion, both populations of MSCs should be used for biological evaluation of biomaterials compatibility, such results may enhance the area of investigations related to regenerative medicine. PMID:25710015

Marycz, Krzysztof; ?mieszek, Agnieszka; Grzesiak, Jakub; Siudzi?ska, Anna; Mar?dziak, Monika; Donesz-Sikorska, Anna; Krzak, Justyna

2015-01-01

330

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

NASA Astrophysics Data System (ADS)

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

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

2014-10-01

331

Synthetic precursor to vertical TiO2 nanowires  

NASA Astrophysics Data System (ADS)

An easy protocol for improvement in formation of the photoanode in a dye sensitized solar cell is addressed. Specifically, a novel synthesis for the formation of a TiO2 precursor: titanium butanediolate, is detailed. This precursor is found to have higher thermal and temporal stability than commercially available TiO2 precursors and it has successfully been employed in the one-pot synthesis of rutile nanowires grown directly on a conducting substrate: fluorine doped tin oxide (FTO). This synthesis has been further extended to directly form a mixed phase TiO2 film consisting of rutile nanowires along with anatase spherical particles on FTO and this assembly has been used as the photoanode in a dye-sensitized solar cell. The synergistic effect of the two phases has provided a net DSSC efficiency of 4.61% with FF = 61%.

Mishra, B.; Ghildiyal, P.; Agarkar, S.; Khushalani, D.

2014-04-01

332

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

Microsoft Academic Search

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

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

1998-01-01

333

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

PubMed

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

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

2007-04-01

334

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

PubMed Central

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

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

2014-01-01

335

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

336

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

PubMed

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

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

2010-02-01

337

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. PMID:24198485

Banerjee, Arghya Narayan

2011-01-01

338

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

339

Perovskite solar cell with an efficient TiO? compact film.  

PubMed

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

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

2014-09-24

340

Influences on photovoltage performance by interfacial modification of FTO\\/mesoporous TiO 2 using ZnO and TiO 2 as the compact film  

Microsoft Academic Search

An effective ZnO compact film (ZCF) has been introduced at the interface of fluorine doped tin oxide (FTO) substrate and mesoporous TiO2 layer, and its effect on dye-sensitized solar cells (DSSCs) has been compared to that of conventional TiO2 compact film (TCF). The ZCF and TCF prepared by spin-coating method on FTO are characterized by energy-dispersive X-ray spectroscopy (EDX), scanning

Yumin Liu; Xiaohua Sun; Qidong Tai; Hao Hu; Bolei Chen; Niu Huang; Bobby Sebo; Xing-Zhong Zhao

2011-01-01

341

Degradation of Reactive Black 5 using combined electrochemical degradation-solar-light\\/immobilized TiO 2 film process and toxicity evaluation  

Microsoft Academic Search

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?M) with a supporting electrolyte of 2gl?1 NaCl at current density 277Am?2 and pH 4. However, TOC mineralization and A310 removal were low.

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

2008-01-01

342

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

343

Laser annealed composite titanium dioxide electrodes for dye-sensitized solar cells on glass and plastics  

Microsoft Academic Search

We report a rapid and low temperature process for fabricating composite TiO2 electrodes for dye-sensitized solar cells on glass and plastics by in tandem spray deposition and laser annealing. A homogenized KrF excimer laser beam (248 nm) was used to layer-by-layer anneal spray deposited TiO2 nanoparticles. The produced TiO2 film is crack free and contains small particles (30 nm) mixed

Heng Pan; Seung Hwan Ko; Nipun Misra; Costas P. Grigoropoulos

2009-01-01

344

Proliferation and stemness preservation of human adipose-derived stem cells by surface-modified in situ TiO2 nanofibrous surfaces  

PubMed Central

Two important criteria of an ideal biomaterial in the field of stem cells research are to regulate the cell proliferation without the loss of its pluripotency and to direct the differentiation into a specific cell lineage when desired. The present study describes the influence of TiO2 nanofibrous surface structures on the regulation of proliferation and stemness preservation of adipose-derived stem cells (ADSCs). TiO2 nanofiber arrays were produced in situ onto Ti-6Al-4V substrate via a thermal oxidation process and the successful fabrication of these nanostructures was confirmed by field emission scanning electron microscopy (FESEM), energy dispersive spectrometer (EDS), X-ray diffractometer (XRD), and contact angle measurement. ADSCs were seeded on two types of Ti-6Al-4V surfaces (TiO2 nanofibers and flat control), and their morphology, proliferation, and stemness expression were analyzed using FESEM, AlamarBlue assay, flow cytometry, and quantitative real-time polymerase chain reaction (qRT-PCR) after 2 weeks of incubation, respectively. The results show that ADSCs exhibit better adhesion and significantly enhanced proliferation on the TiO2 nanofibrous surfaces compared to the flat control surfaces. The greater proliferation ability of TiO2 nanofibrous surfaces was further confirmed by the results of cell cycle assay. More importantly, TiO2 nanofibrous surfaces significantly upregulate the expressions of stemness markers Sox-2, Nanog3, Rex-1, and Nestin. These results demonstrate that TiO2 nanofibrous surfaces can be used to enhance cell adhesion and proliferation while simultaneously maintaining the stemness of ADSCs, thereby representing a promising approach for their potential application in the field of bone tissue engineering as well as regenerative therapies. PMID:25473278

Tan, Ai Wen; Tay, Lelia; Chua, Kien Hui; Ahmad, Roslina; Ali Akbar, Sheikh; Pingguan-Murphy, Belinda

2014-01-01

345

Influence of integration of TiO2 nanorods into its nanodot films on pre-osteoblast cell responses.  

PubMed

Design of an implant surface with appropriate nanostructures has been considered to be an effective way to promote osteoblast cell growth and osseointegration. In this work, TiO2 nanorods were integrated into TiO2 nanodot films by hydrothermal growth to engineer a nanostructured surface composed of two nano-structural elements. The surface microstructure of the films depended on the integration degree. Low integration led to a surface nanostructure with exposure of the two nano-structural elements, and high integration resulted in a similar surface to a nanorod film. The nanorod integration had an obvious influence on pre-osteoblast cell responses and accelerated the cellular osteogenesis. Two factors of the integrated nano-structural element and the changed surface topology are believed to be responsible for enhancing cellular responses. The former is considered to play a more significant role because the nanorods tended to adsorb human fibronectin preferentially so as to begin differentiation to osteogenesis earlier. We anticipate this work may assist to gain insight into understanding of the interactions between nanostructured surfaces with cells. PMID:25511438

Cheng, Kui; Yu, Mengfei; Liu, Yang; Ge, Fei; Lin, Jun; Weng, Wenjian; Wang, Huiming

2015-02-01

346

Strategies to prepare TiO2 thin films, doped with transition metal ions, that exhibit specific physicochemical properties to support osteoblast cell adhesion and proliferation.  

PubMed

Metal ion doped titanium oxide (TiO2) thin films, as bioactive coatings on metal or other implantable materials, can be used as surfaces for studying the cell biological properties of osteogenic and other cell types. Bulk crystallite phase distribution and surface carbon-oxygen constitution of thin films, play an important role in determining the biological responses of cells that come in their contact. Here we present a strategy to control the polarity of atomic interactions between the dopant metal and TiO2 molecules and obtain surfaces with smaller crystallite phases and optimal surface carbon-oxygen composition to support the maximum proliferation and adhesion of osteoblast cells. Our results suggest that surfaces, in which atomic interactions between the dopant metals and TiO2 were less polar, could support better adhesion, spreading and proliferation of cells. PMID:24582228

Dhayal, Marshal; Kapoor, Renu; Sistla, Pavana Goury; Pandey, Ravi Ranjan; Kar, Satabisha; Saini, Krishan Kumar; Pande, Gopal

2014-04-01

347

Electrospinning processed nanofibrous TiO2 membranes for photovoltaic applications  

NASA Astrophysics Data System (ADS)

We have recently fabricated dye-sensitized solar cells (DSSCs) comprising nanofibrous TiO2 membranes as electrode materials. A thin TiO2 film was pre-deposited on fluorine doped tin oxide (FTO) coated conducting glass substrate by immersion in TiF4 aqueous solution to reduce the electron back-transfer from FTO to the electrolyte. The composite polyvinyl acetate (PVac)/titania nanofibrous membranes can be deposited on the pre-deposited thin TiO2 film coated FTO by electrospinning of a mixture of PVac and titanium isopropoxide in N,N-dimethylformamide (DMF). The nanofibrous TiO2 membranes were obtained by calcining the electrospun composite nanofibres of PVac/titania as the precursor. Spectral sensitization of the nanofibrous TiO2 membranes was carried out with a ruthenium (II) complex, cis-dithiocyanate-N,N'-bis(2,2'-bipyridyl-4,4'-dicarboxylic acid) ruthenium (II) dihydrate. The results indicated that the photocurrent and conversion efficiency of electrodes can be increased with the addition of the pre-deposited TiO2 film and the adhesion treatment using DMF. Additionally, the dye loading, photocurrent, and efficiency of the electrodes were gradually increased by increasing the average thickness of the nanofibrous TiO2 membranes. The efficiency of the fibrous TiO2 photoelectrode with the average membrane thickness of 3.9 µm has a maximum value of 4.14%.

Onozuka, Katsuhiro; Ding, Bin; Tsuge, Yosuke; Naka, Takayuki; Yamazaki, Michiyo; Sugi, Shinichiro; Ohno, Shingo; Yoshikawa, Masato; Shiratori, Seimei

2006-02-01

348

A novel nanocomposite based on TiO2/Cu2O/reduced graphene oxide with enhanced solar-light-driven photocatalytic activity  

NASA Astrophysics Data System (ADS)

A novel nanocomposite composed of TiO2 and Cu2O nanoparticles combined with reduced graphene oxide (RGO) was synthesized and characterized. X-ray diffraction (XRD), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), UV-vis diffuse reflectance spectroscopy (UV-vis DRS), X-ray photoelectron spectroscopy (XPS), thermogravimetry (TG) and elemental analysis were employed to investigate the structure, morphology, optical properties and composition of the nanocomposite and the intermediate materials. The photocatalytic activity of TiO2/Cu2O/RGO and the individual materials were studied through the photodegradation of methylene blue under solar radiation. A considerable increase in the photodegradation activity using the nanocomposite was obtained after 5 h (?95% of MB degradation). Photoelectrochemical studies were carried out and confirmed the superiority of the novel nanocomposite in the photocurrent generation. The highest activity resulted from the synergy of this carbonaceous structure with TiO2 and Cu2O, which could absorb a wider portion of the solar spectrum, adsorb higher quantities of methylene blue on the surface and improve the effective separation of the generated electron-hole pairs.

Almeida, Bruna M.; Melo, Maurício A., Jr.; Bettini, Jefferson; Benedetti, João E.; Nogueira, Ana F.

2015-01-01

349

Degradation of microcystin-LR by highly efficient AgBr/Ag3PO4/TiO2 heterojunction photocatalyst under simulated solar light irradiation  

NASA Astrophysics Data System (ADS)

A novel photocatalyst AgBr/Ag3PO4/TiO2 was developed by a simple facile in situ deposition method and used for degradation of mirocystin-LR. TiO2 (P25) as a cost effective chemical was used to improve the stability of AgBr/Ag3PO4 under simulated solar light irradiation. The photocatalytic activity tests for this heterojunction were conducted under simulated solar light irradiation using methyl orange as targeted pollutant. The results indicated that the optimal Ag to Ti molar ratio for the photocatalytic activity of the resulting heterojunction AgBr/Ag3PO4/TiO2 was 1.5 (named as 1.5 BrPTi), which possessed higher photocatalytic capacity than AgBr/Ag3PO4. The 1.5 BrPTi heterojunction was also more stable than AgBr/Ag3PO4 in photocatalysis. This highly efficient and relatively stable photocatalyst was further tested for degradation of the hepatotoxin microcystin-LR (MC-LR). The results suggested that MC-LR was much more easily degraded by 1.5 BrPTi than by AgBr/Ag3PO4. The quenching effects of different scavengers proved that reactive h+ and •OH played important roles for MC-LR degradation.

Wang, Xin; Utsumi, Motoo; Yang, Yingnan; Li, Dawei; Zhao, Yingxin; Zhang, Zhenya; Feng, Chuanping; Sugiura, Norio; Cheng, Jay Jiayang

2015-01-01

350

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.

351

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

352

Electrospinning processed nanofibrous TiO2 membranes for photovoltaic applications  

Microsoft Academic Search

We have recently fabricated dye-sensitized solar cells (DSSCs) comprising nanofibrous TiO2 membranes as electrode materials. A thin TiO2 film was pre-deposited on fluorine doped tin oxide (FTO) coated conducting glass substrate by immersion in TiF4 aqueous solution to reduce the electron back-transfer from FTO to the electrolyte. The composite polyvinyl acetate (PVac)\\/titania nanofibrous membranes can be deposited on the pre-deposited

Katsuhiro Onozuka; Bin Ding; Yosuke Tsuge; Takayuki Naka; Michiyo Yamazaki; Shinichiro Sugi; Shingo Ohno; Masato Yoshikawa; Seimei Shiratori

2006-01-01

353

Effects of various TiO2 nanostructures and graphene oxide on photocatalytic activity of TiO2.  

PubMed

The nanostructures of TiO2 significantly affect its photocatalytic activity. In this work, various TiO2 nanostructures have been successfully synthesized, including one-dimensional (1D) TiO2 nanotube, 1D TiO2 nanowire, three-dimensional (3D) TiO2 sphere assembled by nanoparticles (TiO2 sphere-P) and 3D TiO2 sphere assembled by nanosheets (TiO2 sphere-S). The results of photodegradation activity towards acid orange 7 (AO7) indicate that the photodegradation efficiency of TiO2 sphere-S is the highest among the investigated TiO2 nanostructures, even though the specific surface area of TiO2 sphere-S is lower than that of TiO2 nanotube. The best photodegradation activity of TiO2 sphere-S can be attributed to the highest light harvesting capacity resulted from multiple reflections of light, and hierarchical mesoporous structure. In addition, the combination of TiO2 sphere-S with graphene oxide (GO) sheets can further enhance the photodegradation efficiency of AO7 and disinfection activity of Escherichia coli (E. coli) under solar light, which is more energy efficient. The promising photocatalytic activity of GO-TiO2 composites is originated from the enhanced light absorption and efficient charge separation. Hence, this study paves a way for improving the performance of other photocatalysts. PMID:25038577

Gao, Peng; Li, Anran; Sun, Darren Delai; Ng, Wun Jern

2014-08-30

354

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 ...

355

Intestinal toxicity evaluation of TiO2 degraded surface-treated nanoparticles: a combined physico-chemical and toxicogenomics approach in caco-2 cells  

PubMed Central

Background Titanium dioxide (TiO2) nanoparticles (NPs) are widely used due to their specific properties, like UV filters in sunscreen. In that particular case TiO2 NPs are surface modified to avoid photocatalytic effects. These surface-treated nanoparticles (STNPs) spread in the environment and might release NPs as degradation residues. Indeed, degradation by the environment (exposure to UV, water and air contact …) will occur and could profoundly alter the physicochemical properties of STNPs such as chemistry, size, shape, surface structure and dispersion that are important parameters for toxicity. Although the toxicity of surface unmodified TiO2 NPs has been documented, nothing was done about degraded TiO2 STNPs which are the most likely to be encountered in environment. The superoxide production by aged STNPs suspensions was tested and compared to surface unmodified TiO2 NPs. We investigated the possible toxicity of commercialized STNPs, degraded by environmental conditions, on human intestinal epithelial cells. STNPs sizes and shape were characterized and viability tests were performed on Caco-2 cells exposed to STNPs. The exposed cells were imaged with SEM and STNPs internalization was researched by TEM. Gene expression microarray analyses were performed to look for potential changes in cellular functions. Results The production of reactive oxygen species was detected with surface unmodified TiO2 NPs but not with STNPs or their residues. Through three different toxicity assays, the STNPs tested, which have a strong tendency to aggregate in complex media, showed no toxic effect in Caco-2 cells after exposures to STNPs up to 100??g/mL over 4?h, 24?h and 72?h. The cell morphology remained intact, attested by SEM, and internalization of STNPs was not seen by TEM. Moreover gene expression analysis using pangenomic oligomicroarrays (4x 44000 genes) did not show any change versus unexposed cells after exposure to 10??g/ mL, which is much higher than potential environmental concentrations. Conclusions TiO2 STNPs, degraded or not, are not harmful to Caco-2 cells and are unlikely to penetrate the body via oral route. It is likely that the strong persistence of the aluminium hydroxide layer surrounding these nanoparticles protects the cells from a direct contact with the potentially phototoxic TiO2 core. PMID:22650444

2012-01-01

356

TiO2-doped phosphate glass microcarriers: A stable bioactive substrate for expansion of adherent mammalian cells  

PubMed Central

Scalable expansion of cells for regenerative cell therapy or to produce large quantities for high-throughput screening remains a challenge for bioprocess engineers. Laboratory scale cell expansion using t-flasks requires frequent passaging that exposes cells to many poorly defined bioprocess forces that can cause damage or alter their phenotype. Microcarriers offer a potential solution to scalable production, lending themselves to cell culture processes more akin to fermentation, removing the need for frequent passaging throughout the expansion period. One main problem with microcarrier expansion, however, is the difficulty in harvesting cells at the end of the process. Therefore, therapies that rely on cell delivery using biomaterial scaffolds could benefit from a microcarrier expansion system whereby the cells and microcarriers are transplanted together. In the current study, we used bioactive glass microcarriers doped with 5% TiO2 that display a controlled rate of degradation and conducted experiments to assess biocompatibility and growth of primary fibroblast cells as a model for cell therapy products. We found that the microcarriers are highly biocompatible and facilitate cell growth in a gradual controlled manner. Therefore, even without additional biofunctionalization methods, Ti-doped bioactive glass microcarriers offer potential as a cell expansion platform. PMID:22935537

Guedes, Joana C; Park, Jeong-Hui; Lakhkar, Nilay J; Kim, Hae-Won; Knowles, Jonathan C

2013-01-01

357

Enhancement of solar light photocatalytic activity of TiO2-CeO2 composite by Er3+:Y3Al5O12 in organic dye degradation  

NASA Astrophysics Data System (ADS)

The Er3+:Y3Al5O12, as an upconversion luminescence agent which is able to transform the visible part of the solar light to ultraviolet light, was prepared by nitrate-citrate sol-gel method. A novel solar light photocatalyst, Er3+:Y3Al5O12/TiO2-CeO2 composite was synthesized using ultrasonic treatment. The X-ray diffraction (XRD) and scanning election microscopy (SEM) were used to characterize the structural morphology of the Er3+:Y3Al5O12/TiO2-CeO2 composite. In order to evaluate the solar light photocatalytic activity of Er3+:Y3Al5O12/TiO2-CeO2 composite, the Azo Fuchsine dye was used as a model organic pollutant. The progress of the degradation reaction was monitored by UV-Vis spectroscopy and ion chromatography. The key influences on the solar light photocatalytic activity of Er3+:Y3Al5O12/TiO2-CeO2 were studied, such as Ti/Ce molar ratio, heat-treatment temperature and heat-treatment time. Otherwise, the effects of initial dye concentration, Er3+:Y3Al5O12/TiO2-CeO2 amount, solar light irradiation time and the nature of the dye on the solar light photocatalytic degradation process were investigated. It was found that the solar light photocatalytic activity of Er3+:Y3Al5O12/TiO2-CeO2 composite was superior to Er3+:Y3Al5O12/TiO2 and Er3+:Y3Al5O12/CeO2 powder in the similar conditions.

Li, Y.; Li, S. G.; Zhang, L.; Wang, J.; Li, Y.; Ma, C. H.

2014-12-01

358

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

359

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. PMID:21711880

2011-01-01

360

Combined cytotoxic effect of UV-irradiation and TiO2 microbeads in normal urothelial cells, low-grade and high-grade urothelial cancer cells.  

PubMed

The differentiation of urothelial cells results in normal terminally differentiated cells or by alternative pathways in low-grade or high-grade urothelial carcinomas. Treatments with traditional surgical and chemotherapeutical approaches are still inadequate and expensive, as bladder tumours are generally highly recurrent. In such situations, alternative approaches, using irradiation of the cells and nanoparticles, are promising. The ways in which urothelial cells, at different differentiation levels, respond to UV-irradiation (photolytic treatment) or to the combination of UV-irradiation and nanoparticles (photocatalytic treatment), are unknown. Here we tested cytotoxicity of UV-irradiation on (i) normal porcine urothelial cells (NPU), (ii) human low-grade urothelial cancer cells (RT4), and (iii) human high-grade urothelial cancer cells (T24). The results have shown that 1 minute of UV-irradiation is enough to kill 90% of the cells in NPU and RT4 cultures, as determined by the live/dead viability assay. On the other hand, the majority of T24 cells survived 1 minute of UV-irradiation. Moreover, even a prolonged UV-irradiation for 30 minutes killed <50% of T24 cells. When T24 cells were pre-supplemented with mesoporous TiO2 microbeads and then UV-irradiated, the viability of these high-grade urothelial cancer cells was reduced to <10%, which points to the highly efficient cytotoxic effects of TiO2 photocatalysis. Using electron microscopy, we confirmed that the mesoporous TiO2 microbeads were internalized into T24 cells, and that the cell's ultrastructure was heavily compromised after UV-irradiation. In conclusion, our results show major differences in the sensitivity to UV-irradiation among the urothelial cells with respect to cell differentiation. To achieve an increased cytotoxicity of urothelial cancer cells, the photocatalytic approach is recommended. PMID:25385056

Imani, Roghayeh; Verani?, Peter; Igli?, Aleš; Kreft, Mateja Erdani; Pazoki, Meysam; Hudoklin, Samo

2015-03-01

361

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

Microsoft Academic Search

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

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

2010-01-01

362

Rapid and controllable flame reduction of TiO2 nanowires for enhanced solar water-splitting.  

PubMed

We report a new flame reduction method to generate controllable amount of oxygen vacancies in TiO2 nanowires that leads to nearly three times improvement in the photoelectrochemical (PEC) water-splitting performance. The flame reduction method has unique advantages of a high temperature (>1000 °C), ultrafast heating rate, tunable reduction environment, and open-atmosphere operation, so it enables rapid formation of oxygen vacancies (less than one minute) without damaging the nanowire morphology and crystallinity and is even applicable to various metal oxides. Significantly, we show that flame reduction greatly improves the saturation photocurrent densities of TiO2 nanowires (2.7 times higher), ?-Fe2O3 nanowires (9.4 times higher), ZnO nanowires (2.0 times higher), and BiVO4 thin film (4.3 times higher) in comparison to untreated control samples for PEC water-splitting applications. PMID:24295287

Cho, In Sun; Logar, Manca; Lee, Chi Hwan; Cai, Lili; Prinz, Fritz B; Zheng, Xiaolin

2014-01-01

363

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

364

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

365

Nanocoral architecture of TiO 2 by hydrothermal process: Synthesis and characterization  

NASA Astrophysics Data System (ADS)

TiO2 thin films with novel nanocoral-like morphology were successfully grown directly onto the glass and conducting fluorine doped tin oxide coated glass substrates via multi-step hydrothermal (MSH) process. Titanium chloroalkoxide [TiCl2 (OEt)2 (HOEt)2)] precursor was used in an aqueous saturated NaCl in presence of 1 mM HCl catalyst and HNO3 peptizer at 120 °C. Reaction time varied from 3 to 12 h. The morphological features and physical properties of TiO2 films were investigated by field emission scanning electron microscopy, high resolution transmission electron microscopy, X-ray diffraction, Fourier transform IR spectroscopy, Fourier transform Raman spectroscopy, room temperature photoluminescence spectroscopy and X-ray photoelectron spectroscopy. The surface morphology revealed the formation of TiO2 corals having nanosized (30-40 nm) polyps. The photoelectrochemical properties of the TiO2 nanocoral electrodes were investigated in 0.1 M NaOH electrolyte under UV illumination. The results presented in this study highlight two major findings: (i) ability to tune the photoelectrochemical response and photoconversion efficiency via controlled thickness of TiO2 nanocorals and (ii) the substantial increase in short circuit photocurrent (Jsc) due to the improved charge transport through TiO2 nanocorals prepared via MSH process. This approach would be quite useful for the fabrication of nanocoral architecture that finds key applications in photocatalysis, dye-sensitized solar cells and hybrid solar cells.

Mali, Sawanta S.; Shinde, Pravin S.; Betty, C. A.; Bhosale, Popatrao N.; Lee, Won J.; Patil, Pramod S.

2011-09-01

366

Performance of Caesalpinia sappan heartwood extract as photo sensitizer for dye sensitized solar cells.  

PubMed

A natural dye extracted from Caesalpinia sappan heartwood was used as photo sensitizer for the first time to fabricate titanium dioxide (TiO2) nanoparticles based dye sensitized solar cells. Brazilin and brazilein are the major pigments present in the natural dye and their optimized molecular structure were calculated using Density functional theory (DFT) at 6-31G (d) level. The HOMO-LUMO were performed to reveal the energy gap using optimized structure. Pure TiO2 nanoparticles in anatase phase were synthesized by sol-gel technique. The pure and natural dye sensitized TiO2 nanoparticles were subjected to structural, optical, spectral and morphological studies. Low cost and environment friendly dye sensitized solar cells were fabricated using natural dye sensitized TiO2 based photo anode. The solar light to electron conversion efficiency of Caesalpinia sappan heartwood extract sensitized dye sensitized solar cell is 1.1%. PMID:25233024

Ananth, S; Vivek, P; Saravana Kumar, G; Murugakoothan, P

2015-02-25

367

Performance of Caesalpinia sappan heartwood extract as photo sensitizer for dye sensitized solar cells  

NASA Astrophysics Data System (ADS)

A natural dye extracted from Caesalpinia sappan heartwood was used as photo sensitizer for the first time to fabricate titanium dioxide (TiO2) nanoparticles based dye sensitized solar cells. Brazilin and brazilein are the major pigments present in the natural dye and their optimized molecular structure were calculated using Density functional theory (DFT) at 6-31G (d) level. The HOMO-LUMO were performed to reveal the energy gap using optimized structure. Pure TiO2 nanoparticles in anatase phase were synthesized by sol-gel technique. The pure and natural dye sensitized TiO2 nanoparticles were subjected to structural, optical, spectral and morphological studies. Low cost and environment friendly dye sensitized solar cells were fabricated using natural dye sensitized TiO2 based photo anode. The solar light to electron conversion efficiency of Caesalpinia sappan heartwood extract sensitized dye sensitized solar cell is 1.1%.

Ananth, S.; Vivek, P.; Saravana Kumar, G.; Murugakoothan, P.

2015-02-01

368

Comparative cytotoxicity of Al2O3, CeO2, TiO2 and ZnO nanoparticles to human lung cells.  

PubMed

The increased applications of nanoparticles in a wide range of industrial fields raise the concern about their potential toxicity to human. The aim of this study was to assess and compare the toxicity of four different oxide nanoparticles (Al2O3, CeO2, TiO2 and ZnO) to human lung epithelial cells, A549 carcinoma cells and L-132 normal cells, in vitro. We focused on the toxicological effects of the present nanoparticles on cell proliferation, cell viability, membrane integrity and oxidative stress. The long-term cytotoxicity of nanoparticles was also evaluated by employing the clonogenic assay. Among four nanoparticles tested, ZnO exhibited the highest cytotoxicity in terms of cell proliferation, cell viability, membrane integrity and colony formation in both cell lines. Al2O3, CeO2 and TiO2 showed little adverse effects on cell proliferation and cell viability. However, TiO2 induced oxidative stress in a concentration- and time-dependent manner. CeO2 caused membrane damage and inhibited colony formation in long-term, but with different degree depending on cell lines. Al2O3 seems to be less toxic than the other nanoparticles even after long time exposure. These results highlight the need for caution during manufacturing process of nanomaterials as well as further investigation on the toxicity mechanism. PMID:20358977

Kim, In-Sun; Baek, Miri; Choi, Soo-Jin

2010-05-01

369

Use of titanium dioxide nanoparticles biosynthesized by Bacillus mycoides in quantum dot sensitized solar cells  

PubMed Central

Background One of the major challenges of nanotechnology during the last decade has been the development of new procedures to synthesize nanoparticles. In this context, biosynthetic methods have taken hold since they are simple, safe and eco-friendly. Results In this study, we report the biosynthesis of TiO2 nanoparticles by an environmental isolate of Bacillus mycoides, a poorly described Gram-positive bacterium able to form colonies with novel morphologies. This isolate was able to produce TiO2 nanoparticles at 37°C in the presence of titanyl hydroxide. Biosynthesized nanoparticles have anatase polymorphic structure, spherical morphology, polydisperse size (40–60 nm) and an organic shell as determined by UV–vis spectroscopy, TEM, DLS and FTIR, respectively. Also, conversely to chemically produced nanoparticles, biosynthesized TiO2 do not display phototoxicity. In order to design less expensive and greener solar cells, biosynthesized nanoparticles were evaluated in Quantum Dot Sensitized Solar Cells (QDSSCs) and compared with chemically produced TiO2 nanoparticles. Solar cell parameters such as short circuit current density (ISC) and open circuit voltage (VOC) revealed that biosynthesized TiO2 nanoparticles can mobilize electrons in QDSSCs similarly than chemically produced TiO2. Conclusions Our results indicate that bacterial extracellular production of TiO2 nanoparticles at low temperatures represents a novel alternative for the construction of green solar cells. PMID:25027643

2014-01-01

370

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. PMID:21695039

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

2011-01-01

371

Structural and optoelectronic characterization of TiO2 films prepared using the sol gel technique  

NASA Astrophysics Data System (ADS)

TiO2 is a versatile material that makes for fascinating study in any of its several physical forms: monocrystal, polycrystal, powder or thin film. Its enhanced photosensitivity to UV radiation and excellent chemical stability in acidic and aqueous media point to its excellent potential for use in a variety of applications, such as solar cells, electronic devices, chemical sensors and photocatalysts. Of late, thin films of TiO2 have permitted the study of physical and chemical properties that are almost impossible to examine in powders. Using the sol-gel technique, it was possible to prepare TiO2 films, and to specifically modify their characteristic properties by means of annealing treatments. Optical measurements carried out on sol-gel derived films produced results similar to those found in films prepared using the sputtering technique. The use of TiO2 films facilitates the study of the behaviour of crystalline structure, grain size, photoresponse, electrical conductivity in both darkness and light and energy band gap (Eg) as a function of treatment temperature. For the first time, it has been demonstrated that the photoconductivity of TiO2 becomes apparent at a treatment temperature of 350 °C, which means that below this temperature the material is not photosensitive. The photosensitivity (S) of TiO2 films prepared by the sol-gel technique reaches values between 100 and 104, surpassing by more than two orders of magnitude the photosensitivity of TiO2 in powder form. In addition, it was possible to study the surface crystalline structure, where TEM studies clearly revealed both the polycrystalline order and the atomic arrangements of the TiO2 films. Our findings will afford us an opportunity to better study the nature of TiO2 and to enhance its performance with respect to the above-mentioned applications.

Jiménez González, A. E.; Gelover Santiago, S.

2007-07-01

372

Enhanced photoelectrochemical performance by synthesizing CdS decorated reduced TiO2 nanotube arrays.  

PubMed

The efficient utilization of solar spectrum and photo-induced charge transport are critical aspects in improving the light conversion efficiency of solar cells and hydrogen generation. In this work, reduced TiO2 nanotube arrays with CdS decoration were fabricated through the simple cathodic polarization of annealed TiO2 nanotube arrays followed by the chemical deposition of CdS nanoparticles. Scanning electron microscopy (SEM), X-ray diffraction (XRD) and Raman spectroscopy confirmed the successful fabrication of the target material. UV-visible diffuse reflectance spectra showed a Burstein-Moss shift for reduced TiO2 NTs and a red shift of the absorption edge towards ca. 563 nm for CdS-decorated R-TiO2 NTs. Cyclic voltammetry and impedance spectra together demonstrate the decreased charge transport resistance for reduced TiO2 NTs. Under the excitation of monochromatic light at 420 nm, the proposed CdS-decorated reduced TiO2 NTs exhibit the maximum IPCE value of 30.12% in 1 M Na2SO3 electrolyte, which is almost twice higher than that achieved on CdS-decorated pristine TiO2 NTs. Therefore, the results here highlight the significance of charge transport in the light conversion process. The enhanced charge transport properties are ascribed to the increased number of electrons, which is brought about by the lattice oxygen vacancies (Ti(3+)) during the cathodic polarization. PMID:25265452

Zhang, Qian; Wang, Ling; Feng, Jiangtao; Xu, Hao; Yan, Wei

2014-11-14

373

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

374

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

NASA Astrophysics Data System (ADS)

The nanocrystalline TiO 2 electrode of polythiophene sensitized solar cell was modified by coating gold nanoparticles with thermal decomposition method. The surface concentration of polythiophene adsorbed on TiO 2 electrode was increased obviously due to the participation of gold nanoparticles. The interfacial charge transfer kinetics were investigated by analyzing of photocurrent action spectrum of polythiophene sensitized TiO 2 electrode and fluorescence spectrum of polythiophene solution in the presence of TiO 2 nanocrystals. After modification with Au nanoparticles, short circuit current of polythiophene sensitized solar cell increased from 2.68 mA cm -2 to 3.92 mA cm -2 and power conversion efficiency from 0.88% to 1.30% at AM 1.5.

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

2008-07-01

375

Hybrid Carbon Nanotubes-TiO2 Photoanodes for High Efficiency Dye-Sensitized Solar Cells  

E-print Network

Hybrid Carbon Nanotubes-TiO2 Photoanodes for High Efficiency Dye-Sensitized Solar Cells Kadiatou, 25133 Brescia, Italy Solar Cells Laboratory, Institute of Materials Science and Technology (IMRE photoanodes for dye- sensitized solar cells (DSCs), based on nanocrystalline TiO2 with limited addition

376

Evaluations of the TiO2/simulated solar UV degradations of XAD fractions of natural organic matter from a bog lake using size-exclusion chromatography.  

PubMed

This work reports on the changes in compositions of humic acids (HAs) and fulvic acids (FAs) during photocatalytic degradation. The HAs and FAs were obtained from the XAD-resin fractionation of natural-organic matter (NOM) from a bog lake (Lake Hohloh, Black Forest, Germany). Degussa P-25 titanium dioxide (TiO2) in a suspension and a solar UV simulator (batch reactor) were used in the experiments. The photocatalytic degradation of the HAs and FAs were monitored using size-exclusion chromatography (SEC) equipped with dissolved organic carbon (DOC) and ultraviolet (UV254) detection (SEC-DOC and SEC-UV254) and UV-Vis spectrophotometry. The evolutions of the photocatalytic degradations of the HA and FA fractions were selective. The photocatalytic degradation started with the degradations of high molecular weight compounds with relatively high UV254 absorbances in the HA and FA fractions to yield low molecular weight compounds showing less specific UV254 absorbances. Observance of the same tendency for the original NOM from Lake Hohloh indicates that these XAD-fractions still having complex compound mixtures. However, the larger molecular weight fractions of the FAs showed higher preferential adsorptions onto TiO2, which caused their faster degradation rates. Furthermore, FAs showed a greater reduction of the total THM formation potential (TTHMFP) and the organic halogen compounds adsorbable on activated carbon formation potential (AOXFP), in comparison with the HAs. PMID:23863374

Valencia, Sergio; Marín, Juan M; Restrepo, Gloria; Frimmel, Fritz H

2013-09-15

377

Development of lead iodide perovskite solar cells using three-dimensional titanium dioxide nanowire architectures.  

PubMed

Three-dimensional (3D) nanowire (NW) architectures are considered as superior electrode design for photovoltaic devices compared to NWs or nanoparticle systems in terms of improved large surface area and charge transport properties. In this paper, we report development of lead iodide perovskite solar cells based on a novel 3D TiO2 NW architectures. The 3D TiO2 nanostructure was synthesized via surface-reaction-limited pulsed chemical vapor deposition (SPCVD) technique that also implemented the Kirkendall effect for complete ZnO NW template conversion. It was found that the film thickness of 3D TiO2 can significantly influence the photovoltaic performance. Short-circuit current increased with the TiO2 length, while open-circuit voltage and fill factor decreased with the length. The highest power conversion efficiency (PCE) of 9.0% was achieved with ?600 nm long 3D TiO2 NW structures. Compared to other 1D nanostructure arrays (TiO2 nanotubes, TiO2-coated ZnO NWs and ZnO NWs), 3D TiO2 NW architecture was able to achieve larger amounts of perovskite loading, enhanced light harvesting efficiency, and increased electron-transport property. Therefore, its PCE is 1.5, 2.3, and 2.8 times higher than those of TiO2 nanotubes, TiO2-coated ZnO NWs, and ZnO NWs, respectively. The unique morphological advantages, together with the largely suppressed hysteresis effect, make 3D hierarchical TiO2 a promising electrode selection in designing high-performance perovskite solar cells. PMID:25549153

Yu, Yanhao; Li, Jianye; Geng, Dalong; Wang, Jialiang; Zhang, Lushuai; Andrew, Trisha L; Arnold, Michael S; Wang, Xudong

2015-01-27

378

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

NASA Astrophysics Data System (ADS)

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

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

2010-06-01

379

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

380

Enhanced Energy Conversion Efficiency of the Sr2+-Modified Nanoporous TiO2 Electrode Sensitized  

E-print Network

photon to current efficiency of a solar cell based on the dye Ru[LL(NCS)2] (L ) 2,2-bipyridine-4J at 532 nm. The photoelectrical conversion efficiency is increased from 7.3% to 9.3% under cell based on dye-sensitized nanoporous TiO2 thin film electrode, and power conversion efficiency

Huang, Yanyi

381

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

382

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

PubMed

The killing effect of nitrogen-doped titanium dioxide (N-TiO2) nanoparticles on human cervical carcinoma (HeLa) cells by visible light photodynamic therapy (PDT) was higher than that of TiO2 nanoparticles. To study the mechanism of the killing effect, the reactive oxygen species produced by the visible-light-activated N-TiO2 and pure-TiO2 were evaluated and compared. The changes of the cellular parameters, such as the mitochondrial membrane potential (MMP), intracellular Ca2+, and nitrogen monoxide (NO) concentrations after PDT were measured and compared for N-TiO2- and TiO2-treated HeLa cells. The N-TiO2 resulted in more loss of MMP and higher increase of Ca2+ and NO in HeLa cells than pure TiO2. The cell morphology changes with time were also examined by a confocal microscope. The cells incubated with N-TiO2 exhibited serious distortion and membrane breakage at 60 min after the PDT. PMID:23433090

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

2013-01-01

383

Novel hollow mesoporous 1D TiO2 nanofibers as photovoltaic and photocatalytic materials.  

PubMed

Hollow mesoporous one dimensional (1D) TiO(2) nanofibers are successfully prepared by co-axial electrospinning of a titanium tetraisopropoxide (TTIP) solution with two immiscible polymers; polyethylene oxide (PEO) and polyvinylpyrrolidone (PVP) using a core-shell spinneret, followed by annealing at 450 °C. The annealed mesoporous TiO(2) nanofibers are found to having a hollow structure with an average diameter of 130 nm. Measurements using the Brunauer-Emmett-Teller (BET) method reveal that hollow mesoporous TiO(2) nanofibers possess a high surface area of 118 m(2) g(-1) with two types of mesopores; 3.2 nm and 5.4 nm that resulted from gaseous removal of PEO and PVP respectively during annealing. With hollow mesoporous TiO(2) nanofibers as the photoelectrode in dye sensitized solar cells (DSSC), the solar-to-current conversion efficiency (?) and short circuit current (J(sc)) are measured as 5.6% and 10.38 mA cm(-2) respectively, which are higher than those of DSSC made using regular TiO(2) nanofibers under identical conditions (? = 4.2%, J(sc) = 8.99 mA cm(-2)). The improvement in the conversion efficiency is mainly attributed to the higher surface area and mesoporous TiO(2) nanostructure. It facilitates the adsorption of more dye molecules and also promotes the incident photon to electron conversion. Hollow mesoporous TiO(2) nanofibers with close packing of grains and crystals intergrown with each other demonstrate faster electron diffusion, and longer electron recombination time than regular TiO(2) nanofibers as well as P25 nanoparticles. The surface effect of hollow mesoporous TiO(2) nanofibers as a photocatalyst for the degradation of rhodamine dye was also investigated. The kinetic study shows that the hollow mesoporous surface of the TiO(2) nanofibers influenced its interactions with the dye, and resulted in an increased catalytic activity over P25 TiO(2) nanocatalysts. PMID:22315140

Zhang, Xiang; Thavasi, Velmurugan; Mhaisalkar, S G; Ramakrishna, Seeram

2012-03-01

384

Cell growth on pore-graded biomimetic TiO2 bone scaffolds.  

PubMed

In order to prevent soft tissue down-growth into osseous defect areas, membranes are used when placing bone graft materials. These membranes still show shortcomings in their performance and applications. In the current study, we choose an approach to integrate micro-porous surface structures into a macro-porous scaffold. Low porous surfaces were fabricated by dip-coatings. Four different material compositions (titanium dioxide, polycaprolactone, polycaprolactone/water, polycaprolactone/?-tricalcium phosphate) were characterised in terms of their appearance, architecture, topographical features and cell response. Titanium dioxide surfaces exhibited rougher and more complex textures, resulting in the highest number of osteosarcoma cells and distinct morphologies in terms of cell spreading. Polycaprolactone-based surfaces showed a smoother topography and enhanced microporosity, but the effect on secretion of the bone markers sclerostin and interleukin-6 from human osteoblasts was lower compared to secretion from cells cultured on titanium dioxide. ?-Tricalcium phosphate modification of polycaprolactone did not show any significant improvement regarding cell-material interaction. Nevertheless, surfaces show potential in the mechanical blockage of epithelial and soft tissue cells and may still permit sufficient nutrient transport. PMID:25394623

Müller, Benjamin; Reseland, Janne Elin; Haugen, Håvard Jostein; Tiainen, Hanna

2015-04-01

385

Optical properties of TiO2 nanotube arrays fabricated by the electrochemical anodization method  

NASA Astrophysics Data System (ADS)

Perpendicularly self-aligned TiO2 nanotube samples of size of 3 × 5 cm2 were fabricated by the electrochemical anodization method using a solution containing NH4F. Influences of the technological conditions such as NH4F concentration and anodization voltage were studied. It was found that NH4F concentration in the solution and anodization voltage significantly affect the diameter and length of a TiO2 nanotube. The diameter and the length of a TiO2 nanotube were observed and estimated by using scanning electron microscopy. It has shown that the largest diameter and the longest length of about 80 nm and 20 ?m, respectively, were obtained for the sample anodized in a solution containing 0.4% of NH4F, under a voltage of 48 V. Photoluminescence spectra excited by laser lights having wavelengths of 325 and 442 nm (having energies higher and lower than the band gap energy of TiO2) was recorded at room temperature for the TiO2 nanotube arrays. An abnormal luminescence result was observed. It is experimental evidence that the manufactured TiO2 nanotube array is an expected material for hydrogen splitting from water by photochemical effect under sunlight as well as for the nano solar cells.

Ly, Ngoc Tai; Chien Nguyen, Van; Hoa Dao, Thi; Hoang To, Le Hong; Pham, Duy Long; Do, Hung Manh; Vu, Dinh Lam; Le, Van Hong

2014-03-01

386

Preparation of near micrometer-sized TiO2 nanotube arrays by high voltage anodization.  

PubMed

Highly ordered TiO2 nanotube arrays with large diameter of 680-750 nm have been prepared by high voltage anodization in an electrolyte containing ethylene glycol at room temperature. To effectively suppress dielectric breakdown due to high voltage, pre-anodized TiO2 film was formed prior to the main anodizing process. Vertically aligned, large sized TiO2 nanotubes with double-wall structure have been demonstrated by SEM in detail under various anodizing voltages up to 225 V. The interface between the inner and outer walls in the double-wall configuration is porous. Surface topography of the large diameter TiO2 nanotube array is substantially improved and effective control of the growth of large diameter TiO2 nanotube array is achieved. Interestingly, the hemispherical barrier layer located at the bottom of TiO2 nanotubes formed in this work has crinkles analogous to the morphology of the brain cortex. These structures are potentially useful for orthopedic implants, storage of biological agents for controlled release, and solar cell applications. PMID:25428070

Ni, Jiahua; Noh, Kunbae; Frandsen, Christine J; Kong, Seong Deok; He, Guo; Tang, Tingting; Jin, Sungho

2013-01-01

387

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

388

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 TiO(2) -CdS photoelectrochemical (PEC) cell and its role is examined in the three main components of the cell: 1) the CdS-sensitized TiO(2) photoanode, 2) the cathode, and 3) the S(2-)/S(.-) aqueous redox electrolyte. The nRGO layer is sandwiched between TiO(2) 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 TiO(2) 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 SO(4)(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

389

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

390

Dye-sensitized solar cells with natural dyes extracted from plant seeds  

NASA Astrophysics Data System (ADS)

The application of natural dyes extracted from plant seeds in the fabrication of dye-sensitized solar cells (DSSCs) has been explored. Ten dyes were extracted from different plant seeds and used as sensitizers for DSSCs. The dyes were characterized using UV-Vis spectrophotometry. DSSCs were prepared using TiO2 and ZnO nanostructured mesoporous films. The highest conversion efficiency of 0.875 % was obtained with an allium cepa (onion) extract-sensitized TiO2 solar cell. The process of TiO2-film sintering was studied and it was found that the sintering procedure significantly affects the response of the cell. The short circuit current of the DSSC was found to be considerably enhanced when the TiO2 semiconducting layer was sintered gradually.

El-Ghamri, Hatem S.; El-Agez, Taher M.; Taya, Sofyan A.; Abdel-Latif, Monzir S.; Batniji, Amal Y.

2014-12-01

391

Structural and optoelectronic characterization of TiO2 films prepared using the sol gel technique  

Microsoft Academic Search

TiO2 is a versatile material that makes for fascinating study in any of its several physical forms: monocrystal, polycrystal, powder or thin film. Its enhanced photosensitivity to UV radiation and excellent chemical stability in acidic and aqueous media point to its excellent potential for use in a variety of applications, such as solar cells, electronic devices, chemical sensors and photocatalysts.

A. E. Jiménez González; S. Gelover Santiago

2007-01-01

392

Microfluidic cell with a TiO 2-modified gold electrode irradiated by an UV-LED for in situ photocatalytic decomposition of organic matter and its potentiality for voltammetric analysis of metal ions  

Microsoft Academic Search

A novel microreactor for TiO2-assisted photocatalysis in a microfluidic electrochemical cell was designed and constructed by a technology that can be reproduced in any chemical laboratory. The cell is obtained by a two-step thermal transfer of laser printed masks onto gold CD-Rs, a subtractive one to define the electrodes, and an additive one to define the channels. The TiO2 nanoparticles

Daniela Daniel; Ivano G. R. Gutz

2007-01-01

393

Solar cell  

SciTech Connect

A solar cell and a method of manufacturing the same are disclosed. The solar cell has a semiconducor substrate having a major surface for receiving light, a p-n junction for photovoltatic generation therein and a thin alumina coating layer on the major surface of the semiconductor substrate. The alumina coating layer includes H radicals and OH radicals.

Nakano, H.; Kato, T.; Morita, H.

1984-07-31

394

Electronic and optical properties of TiO2 and its polymorphs by Z-scan method  

NASA Astrophysics Data System (ADS)

TiO2 is a material which has attracted considerable attention from the scientific community for its innumerable properties. TiO2 is known to exist in nature in three different crystalline structures: rutile, anatase, and brookite. Anatase and rutile TiO2 films have been widely characterized for their potential applications in solar cells, self-cleaning coatings, and photocatalysis. In the present report, the third-order nonlinear susceptibilities of TiO2 and its polymorphs, anatase, and rutile, prepared by the sol—gel technique followed by heat treatment are investigated using the Z-scan technique at a wavelength of 532 nm with a duration of 7 ns. Imaginary and real values of ?(3) for amorphous, anatase, and rutile are also calculated and found to be 5 × 10-19 m2/V2, 27 × 10-19 m2/V2, 19 × 10-19 m2/V2, respectively. It is found that the values of the optical constants of amorphous TiO2 after heat treatment vary considerably. It is assumed that this could be due to the variation in the electronic structure of TiO2 synchronous with the formation of its polymorphs, anatase, and rutile. Amorphous TiO2 is marked by the localization of the tail states near the band gap, whereas its crystalline counterparts are characterized by completely delocalized tail states.

Divya, S.; V, P. N. Nampoori; P, Radhakrishnan; A, Mujeeb

2014-08-01

395

Quantum junction solar cells.  

PubMed

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

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

2012-09-12

396

Cost effective facile synthesis of TiO2 nanograins for flexible DSSC application using rose bengal dye  

NASA Astrophysics Data System (ADS)

Synthesis of titanium dioxide (TiO2) nanograins using economical successive ionic layer adsorption and reaction (SILAR) method has been carried out. TiO2 thin films are studied for their structural, compositional, optical and morphological properties. A layer by layer process leads to the formation of 2.4 ?m thick nanocrystalline TiO2 film. The heat treated TiO2 thin films are hydrophilic in nature with contact angle of 67°. The interconnected nanograins are employed for dye sensitized solar cells (DSSC) using inexpensive Rose Bengal (RB) dye. RB dye sensitization resulted into shifting of absorption peak from UV to visible region. The photoresponce of the dye sensitized solar cell is evaluated in the polyiodide electrolyte (0.1 M KI + 0.01 M I2) at 40 mWcm-2 illumination intensity. The TiO2 nanograins accompanied with RB sensitizer showed the conversion efficiency ( ?) of 0.89%. These results depict the strong assurance of TiO2 nanograins for DSSC application.

Jambure, Supriya Bapurao; Gund, Girish Sambhaji; Dubal, Deepak Prakash; Shinde, Sujata Sureshrao; Lokhande, Chandrakant Dnyandev

2014-09-01

397

Photocatalytic degradation of cylindrospermopsin under UV-A, solar and visible light using TiO2. Mineralization and intermediate products.  

PubMed

Cyanobacteria (blue-green algae) are considered an important water quality problem, since several genera can produce toxins, called cyanotoxins that are harmful to human health. Cylindrospermopsin (CYN) is an alkaloid-like potent cyanotoxin that has been reported in water reservoirs and lakes worldwide. In this paper the removal of CYN from water by UV-A, solar and visible light photocatalysis was investigated. Two different commercially available TiO2 photocatalysts were used, i.e., Degussa P25 and Kronos-vlp7000. Complete degradation of CYN was achieved with both photocatalysts in 15 and 40 min under UV-A and 40 and 120 min under solar light irradiation, for Degussa P25 and Kronos vlp-7000 respectively. Experiments in the absence of photocatalysts showed that direct photolysis was negligible. Under visible light irradiation only the Kronos vlp-7000 which is a visible light activated catalyst was able to degrade CYN. A number of intermediates were identified and a complete degradation pathway is proposed, leading to the conclusion that hydroxyl radical attack is the main mechanism followed. TOC and inorganic ions (NO2-, NO3-, SO4(2-) and NH4+) determinations suggested that complete mineralization of CYN was achieved under UV-A in the presence of Degussa P25. PMID:24846598

Fotiou, Theodora; Triantis, Theodoros; Kaloudis, Triantafyllos; Hiskia, Anastasia

2015-01-01

398

The nearly 100% filling of PEDOT in TiO2 nanotube array by a simple electropolymerization method  

NASA Astrophysics Data System (ADS)

A nearly 100% filling of PEDOT in TiO2 nanotube array (NTA) was successfully prepared by a simple electropolymerization method at a constant potential of 1.8 V, which was demonstrated by field emission scanning electron microscopy (FESEM). UV-vis diffusion reflection spectroscopy (DRS) revealed that the filling of PEDOT in TiO2 NTA can dramatically improve the visible-light and near-infra-red absorption property of the TiO2 NTA, which is especially useful for the application of solar cells. Cyclic voltammetry experiments indicate that the PEDOT-TiO2 NTA hybrid material is electrochemically more active than the TiO2 NTA and has excellent redox reversibility.

Yang, Xiuchun; Chi, Lina; Chen, Chao; Cui, Xiaolin; Wang, Qingyao

2015-02-01

399

TiO2 thin films prepared via adsorptive self-assembly for self-cleaning applications.  

PubMed

Low-cost controllable solution-based processes for preparation of titanium oxide (TiO(2)) thin films are highly desirable, because of many important applications of this oxide in catalytic decomposition of volatile organic compounds, advanced oxidation processes for wastewater and bactericidal treatments, self-cleaning window glass for green intelligent buildings, dye-sensitized solar cells, solid-state semiconductor metal-oxide solar cells, self-cleaning glass for photovoltaic devices, and general heterogeneous photocatalysis for fine chemicals etc. In this work, we develop a solution-based adsorptive self-assembly approach to fabricate anatase TiO(2) thin films on different glass substrates such as simple plane glass and patterned glass at variable compositions (normal soda lime glass or solar-grade borofloat glass). By tuning the number of process cycles (i.e., adsorption-then-heating) of TiO(2) colloidal suspension, we could facilely prepare large-area TiO(2) films at a desired thickness and with uniform crystallite morphology. Moreover, our as-prepared nanostructured TiO(2) thin films on glass substrates do not cause deterioration in optical transmission of glass; instead, they improve optical performance of commercial solar cells over a wide range of incident angles of light. Our as-prepared anatase TiO(2) thin films also display superhydrophilicity and excellent photocatalytic activity for self-cleaning application. For example, our investigation of photocatalytic degradation of methyl orange indicates that these thin films are indeed highly effective, in comparison to other commercial TiO(2) thin films under identical testing conditions. PMID:22260264

Xi, Baojuan; Verma, Lalit Kumar; Li, Jing; Bhatia, Charanjit Singh; Danner, Aaron James; Yang, Hyunsoo; Zeng, Hua Chun

2012-02-01

400

TiO2 -coated CoCrMo: Improving the osteogenic differentiation and adhesion of mesenchymal stem cells in vitro.  

PubMed

The current gold standard material for orthopedic applications is titanium (Ti), however, other materials such as cobalt-chromium-molybdenum (CoCrMo) are often preferred due to their wear resistance and mechanical strength. This study investigates if the bioactivity of CoCrMo can be enhanced by coating the surface with titanium oxide (TiO2 ) by atmospheric pressure chemical vapor deposition (CVD), thereby replicating the surface oxide layer found on Ti. CoCrMo, TiO2 -coated CoCrMo (CCMT) and Ti substrates were used for this study. Cellular f-actin distribution was shown to be noticeably different between cells on CCMT and CoCrMo after 24 h in osteogenic culture, with cells on CCMT exhibiting greater spread with developed protrusions. Osteogenic differentiation was shown to be enhanced on CCMT compared to CoCrMo, with increased calcium ion content per cell (p?cell (p?cell from the substrate surface compared to CoCrMo (p?

Logan, Niall; Sherif, Anas; Cross, Alison J; Collins, Simon N; Traynor, Alison; Bozec, Laurent; Parkin, Ivan P; Brett, Peter

2015-03-01

401

Hybrid poly (3-hexylthiophene)\\/titanium dioxide nanorods material for solar cell applications  

Microsoft Academic Search

We conducted an extensive study on poly(3-hexylthiophene) (P3HT) in combination with titanium dioxide (TiO2) nanorods hybrid material for polymer solar cell applications. The device performance critically depends on the morphology of the hybrid film that will be determined by the molecular weight of P3HT, the solvent type, the hybrid compositions, the surface ligand on the TiO2 nanorods, film thickness, process

Tsung-Wei Zeng; Hsi-Hsing Lo; Chia-Hao Chang; Yun-Yue Lin; Chun-Wei Chen; Wei-Fang Su

2009-01-01

402

Graphene nanosheet counter-electrodes for dye-sensitized solar cells  

Microsoft Academic Search

Graphene nanosheets (GNs) have been investigated as a counter electrode for dye-sensitized solar cells (DSCs). Mesoporous TiO2 films are prepared from the commercial TiO2 nano-powders by screen-printing technique on fluorine-doped tin oxide (FTO) slides. GNs are applied to substitute for platinum as counter-electrode materials. GN films are screen printed on FTO glass using a paste based on GNs dispersed in

D. W. Zhang; X. D. Li; S. Chen; H. B. Li; Z. Sun; X. J. Yin; S. M. Huang

2010-01-01

403

A Surface Resistance Effect on the Fabrication of Dye-sensitized Solar Cell with Various Widths  

Microsoft Academic Search

Sputter deposition followed by surface treatment was studied using reactive RF plasma as a method for preparing titanium oxide (TiO2) films on the FTO (fluorine doped tin oxide, SnO2: F) substrate for dye-sensitized solar cells (DSCs). Anatase structure TiO2 films deposited by reactive RF magnetron sputtering under the conditions of Ar\\/O2 (5%) mixing gas, RF power of 600 W and

Jin-Young Choi; Hyun-Woong Seo; Mi-Jeong Kim; Ji-Young Sim; Dong-Yoon Lee; Hee-Je Kim

2008-01-01

404

Improvement of the performance of inverted polymer solar cells with a fluorine-doped tin oxide electrode  

Microsoft Academic Search

We prepared the inverted polymer solar cells (PSCs) with a fluorine-doped tin oxide (FTO) as a transparent electrode and with TiO2, WO3 and WOx as selective charge transport layers. An adequately thick TiO2 nanoparticles layer was employed for covering a very rough FTO surface. Using a solution-based WOx film instead of a vacuum deposited WO3 layer in inverted polymer solar

Jae-Ryoung Kim; Jung Min Cho; A-Rum Lee; Eun Ah Chae; Jin-Uk Park; Won-Bae Byun; Sang Kyu Lee; Jong-Cheol Lee; Won-Wook So; Seunghyup Yoo; Sang-Jin Moon; Won Suk Shin

2011-01-01

405

Novel hollow mesoporous 1D TiO2 nanofibers as photovoltaic and photocatalytic materials  

NASA Astrophysics Data System (ADS)

Hollow mesoporous one dimensional (1D) TiO2 nanofibers are successfully prepared by co-axial electrospinning of a titanium tetraisopropoxide (TTIP) solution with two immiscible polymers; polyethylene oxide (PEO) and polyvinylpyrrolidone (PVP) using a core-shell spinneret, followed by annealing at 450 °C. The annealed mesoporous TiO2 nanofibers are found to having a hollow structure with an average diameter of 130 nm. Measurements using the Brunauer-Emmett-Teller (BET) method reveal that hollow mesoporous TiO2 nanofibers possess a high surface area of 118 m2 g-1 with two types of mesopores; 3.2 nm and 5.4 nm that resulted from gaseous removal of PEO and PVP respectively during annealing. With hollow mesoporous TiO2 nanofibers as the photoelectrode in dye sensitized solar cells (DSSC), the solar-to-current conversion efficiency (?) and short circuit current (Jsc) are measured as 5.6% and 10.38 mA cm-2 respectively, which are higher than those of DSSC made using regular TiO2 nanofibers under identical conditions (? = 4.2%, Jsc = 8.99 mA cm-2). The improvement in the conversion efficiency is mainly attributed to the higher surface area and mesoporous TiO2 nanostructure. It facilitates the adsorption of more dye molecules and also promotes the incident photon to electron conversion. Hollow mesoporous TiO2 nanofibers with close packing of grains and crystals intergrown with each other demonstrate faster electron diffusion, and longer electron recombination time than regular TiO2 nanofibers as well as P25 nanoparticles. The surface effect of hollow mesoporous TiO2 nanofibers as a photocatalyst for the degradation of rhodamine dye was also investigated. The kinetic study shows that the hollow mesoporous surface of the TiO2 nanofibers influenced its interactions with the dye, and resulted in an increased catalytic activity over P25 TiO2 nanocatalysts.Hollow mesoporous one dimensional (1D) TiO2 nanofibers are successfully prepared by co-axial electrospinning of a titanium tetraisopropoxide (TTIP) solution with two immiscible polymers; polyethylene oxide (PEO) and polyvinylpyrrolidone (PVP) using a core-shell spinneret, followed by annealing at 450 °C. The annealed mesoporous TiO2 nanofibers are found to having a hollow structure with an average diameter of 130 nm. Measurements using the Brunauer-Emmett-Teller (BET) method reveal that hollow mesoporous TiO2 nanofibers possess a high surface area of 118 m2 g-1 with two types of mesopores; 3.2 nm and 5.4 nm that resulted from gaseous removal of PEO and PVP respectively during annealing. With hollow mesoporous TiO2 nanofibers as the photoelectrode in dye sensitized solar cells (DSSC), the solar-to-current conversion efficiency (?) and short circuit current (Jsc) are measured as 5.6% and 10.38 mA cm-2 respectively, which are higher than those of DSSC made using regular TiO2 nanofibers under identical conditions (? = 4.2%, Jsc = 8.99 mA cm-2). The improvement in the conversion efficiency is mainly attributed to the higher surface area and mesoporous TiO2 nanostructure. It facilitates the adsorption of more dye molecules and also promotes the incident photon to electron conversion. Hollow mesoporous TiO2 nanofibers with close packing of grains and crystals intergrown with each other demonstrate faster electron diffusion, and longer electron recombination time than regular TiO2 nanofibers as well as P25 nanoparticles. The surface effect of hollow mesoporous TiO2 nanofibers as a photocatalyst for the degradation of rhodamine dye was also investigated. The kinetic study shows that the hollow mesoporous surface of the TiO2 nanofibers influenced its interactions with the dye, and resulted in an increased catalytic activity over P25 TiO2 nanocatalysts. Electronic supplementary information (ESI) available. See DOI: 10.1039/c2nr11251e

Zhang, Xiang; Thavasi, Velmurugan; Mhaisalkar, S. G.; Ramakrishna, Seeram

2012-02-01

406

Weavable dye sensitized solar cells exploiting carbon nanotube yarns  

NASA Astrophysics Data System (ADS)

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

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

2013-05-01

407

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

408

Monolithic quantum dot sensitized solar cells  

NASA Astrophysics Data System (ADS)

We report a new design of solar cells based on semiconductor quantum dots (QDs), monolithic quantum dot sensitized solar cells (MQDSCs). MQDSCs offer the prospect of having lower cost and a simpler manufacturing process in comparison to conventional double substrate QDSCs. Our proposed monolithic QDSCs have a triple-layer structure, composed of a CdS sensitized mesoporous TiO2 photoanode, a scattering layer made by a core-shell structure of TiO2/SiO2, and a carbon active/graphite counter electrode layer, which are all deposited on a single fluorine doped tin oxide (FTO) glass substrate. Mesoporous TiO2 was sensitized with CdS QDs by successive ionic layer adsorption and reaction. Here, non-conventional solvents were utilized, which made it possible to deposit the CdS QDs in our monolithic structure. The measured photovoltaic properties and simple preparation method show that MQDSCs can be introduced as promising structures to make low-cost QDSCs in the near future.

Samadpour, M.; Ghane, Z.; Ghazyani, N.; Tajabadi, F.; Taghavinia, N.

2013-12-01

409

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

PubMed

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

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

2012-01-16

410

Efficient photoinduced charge transfer in TiO2 nanorod/conjugated polymer hybrid materials  

NASA Astrophysics Data System (ADS)

The mechanisms of photoinduced charge transfer in composites of TiO2 nanorods with a conjugated polymer (poly(2-methoxy-5-(2'-ethyl)(hexyloxy) 1,4-phenylenevinylene) (MEH-PPV) have been investigated by steady-state, time-resolved photoluminescence (PL) spectroscopy and photoluminescence excitation (PLE) spectroscopy. Efficient charge separation takes place at the TiO2-nanorod/polymer interfaces when the polymer is excited, leading to quenching of the photoluminescence efficiency ? and shortening of the measured lifetime ?PL. In addition, the low-temperature absorption and photoluminescence spectra show that the inclusion of TiO2 nanorods in polymer can reduce disorder in conformation and enhance conjugation in the polymer chain. A photovoltaic solar cell device based on the MEH-PPV/TiO2-nanorod composite material is also presented, which shows a two order increase in short-circuit current JSC compared to that based on the pristine MEH-PPV.

Lin, Yu-Ting; Zeng, Tsung-Wei; Lai, Wei-Zong; Chen, Chun-Wei; Lin, Yun-Yue; Chang, Yu-Sheng; Su, Wei-Fang

2006-12-01

411

Nuclear microscopy as a tool in TiO2 nanoparticles bioaccumulation studies in aquatic species  

NASA Astrophysics Data System (ADS)

Engineered Titanium nanoparticles are used for a wide range of applications from coatings, sunscreen cosmetic additives to solar cells or water treatment agents. Inevitably environmental exposure can be expected and data on the ecotoxicological evaluation of nanoparticles are still scarce. The potential effects of nanoparticles of titanium dioxide (TiO2) on two model organisms, the water flea, Daphnia magna and the duckweed Lemna minor, were examined in semichronic toxicity tests. Daphnia and Lemna were exposed to TiO2 nanoparticles (average particle size value of 28 ± 11 nm (n = 42); concentration range, 1.4-25 mg/L) by dietary route and growth in medium containing the nanoparticles of TiO2, respectively. Both morphology and microdistribution of Ti in the individuals were examined by nuclear microscopy techniques. A significant amount of TiO2 was found accumulated in Daphnia exposed to nanoparticles. Nuclear microscopy imaging revealed that Ti was localized only in the digestive tract of the Daphnia, which displayed difficulty in eliminating the nanoparticles from their body. Daphnia showed higher mortality when exposed to higher concentrations of TiO2 (>10 mg/L). The exposure to TiO2 nanoparticles above 25 mg/L caused morphological alterations in Lemna. The roots became stiff and fronds colorless. The Ti mapping of cross-sections of roots and fronds showed that Ti was mainly deposited in the epidermis of the fronds and roots, with minor internalization. In summary, exposure of aquatic organisms to TiO2 nanoparticles may alter the physiology of these organisms at individual and population levels, posing risks to aquatic ecosystems.

Pinheiro, Teresa; Moita, Liliana; Silva, Luís; Mendonça, Elsa; Picado, Ana

2013-07-01

412

Enhanced light-conversion efficiency of titanium-dioxide dye-sensitized solar cells with the addition of indium-tin-oxide and fluorine-tin-oxide nanoparticles in electrode films  

Microsoft Academic Search

We prepared of electrodes that consist of TiO2 with addition of tin-doped indium oxide (ITO) or fluorine-doped tin oxide (FTO) nanoparticles and the application of such electrodes on dye-sensitized solar cell. As compared to TiO2 alone, the addition of ITO and FTO nanoparticles resulted in an efficiency improvement of ~ 20% up to ~ 54% for the TiO2- ITO and

Tammy P. Chou; Qifeng Zhang; Bryan Russo; Guozhong Cao

2008-01-01

413

Multichromophore light harvesting in hybrid solar cells.  

PubMed

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

Bandara, Jayasundera; Willinger, Katja; Thelakkat, Mukundan

2011-07-28

414

Controlled synthesis and facets-dependent photocatalysis of TiO2 nanocrystals  

NASA Astrophysics Data System (ADS)

Titanium dioxide (TiO2) is a wide band gap semiconductor that has been extensively used in several environmental applications including degradation of organic hazardous chemicals, water splitting to generate hydrogen, dye sensitized solar cells, self cleaning agents, and pigments. Herein we demonstrate the synthesis of TiO2 nanocrystals (NCs) with the shapes of ellipsoids, rods, cuboids, and sheets with different exposed facets using a noncorrosive and nontoxic chemical (i.e. diethanolamine) as the shape controlling agent, unlike hydrofluoric acid commonly used. The TiO2 NCs of diverse shapes with different exposed facets were tested for photocatalytic hydroxyl radical (OH•) formation, which determines their photocatalytic behavior and the results were compared with the standard P-25 Degussa. The formation rate of OH• per specific surface area was found to be >6 fold higher for rod-shaped TiO2 NCs than that of commercial Degussa P25 catalyst. The highest photocatalytic activity of rod-shaped TiO2 NCs is ascribed to the unique chemical environment of {010} exposed facets which facilitates the electron/hole separation in presence of {101} facets.

Roy, Nitish; Park, Yohan; Sohn, Youngku; Pradhan, Debabrata

2015-04-01

415

Fabrication of nano-structured TiO2 coatings using a microblast deposition technique  

NASA Astrophysics Data System (ADS)

Micron thick titanium dioxide (TiO2) coatings exhibiting a nano-structured, anatase, meso-porous structure were successfully deposited across a range of polymer, conductive glass and metallic substrates at low velocities using a microblasting technique. This process was conducted at atmospheric pressure using compressed air as the carrier gas and commercially available agglomerated nano particles of TiO2 as the feedstock. An examination of the effect of impact kinetics on the agglomerated powder before and after deposition was undertaken. A further examination of the coating microstructure along with photocurrent density measurements before and after thermal treatments was explored. Owing to the low temperature and velocity of the powder during deposition no change in phase of the powder or damage to the substrate was observed. The resulting TiO2 coatings exhibited relatively good adhesion on both titanium and FTO coated glass substrates with coating thickness of approximately 1.5 ?m. Photo-catalytic performance was measured under solar simulator illumination using a photo-electrochemical cell (PEC) with a 5-fold increase in performance observed after thermal treatment of the TiO2 coated substrates. Microblasting was demonstrated to be a rapid and cost effective method for the deposition of nano-structured, photo-catalytic, anatase TiO2 coatings.

McDonnell, Kevin A.; English, Niall J.; Stallard, Charlie P.; Rahman, Mahfujur; Dowling, Denis P.

2013-06-01

416

Equilibrium lithium transport between nanocrystalline phases in intercalated TiO(2) anatase.  

PubMed

Microcrystalline TiO(2) with an anatase crystal structure is used as an anode material for lithium rechargeable batteries, and also as a material for electrochromic and solar-cell devices. When intercalated with lithium, as required for battery applications, TiO(2) anatase undergoes spontaneous phase separation into lithium-poor (Li(0.01)TiO(2)) and lithium-rich (Li(0.6)TiO(2)) domains on a scale of several tens of nanometres. During discharge, batteries need to maintain a constant electrical potential between their electrodes over a range of lithium concentrations. The two-phase equilibrium system in the electrodes provides such a plateau in potential, as only the relative phase fractions vary on charging (or discharging) of the lithium. Just as the equilibrium between a liquid and a vapour is maintained by a continuous exchange of particles between the two phases, a similar exchange is required to maintain equilibrium in the solid state. But the time and length scales over which this exchange takes place are unclear. Here we report the direct observation by solid-state nuclear magnetic resonance of the continuous lithium-ion exchange between the intermixed crystallographic phases of lithium-intercalated TiO(2). We find that, at room temperature, the continuous flux of lithium ions across the phase boundaries is as high as 1.2 x 10(20) s(-1) m(-2). PMID:12140552

Wagemaker, M; Kentgens, A P M; Mulder, F M

2002-07-25

417

Photocatalytic treatment of water-soluble pesticides by photo-Fenton and TiO 2 using solar energy  

Microsoft Academic Search

The technical feasibility and performance of photocatalytic degradation of four water-soluble pesticides (diuron, imidacloprid, formetanate and methomyl) have been studied at pilot scale in two well-defined systems of special interest because natural-solar UV light can be used: heterogeneous photocatalysis with titanium dioxide and homogeneous photocatalysis by photo-Fenton. The pilot plant is made up of compound parabolic collectors (CPCs) specially designed

S Malato; J Blanco; J Cáceres; A. R Fernández-Alba; A Agüera; A Rodr??guez

2002-01-01

418

Electrochemical impedance spectroscopic analysis of dye-sensitized solar cells.  

PubMed

Electrochemical impedance spectroscopy (EIS) has been performed to investigate electronic and ionic processes in dye-sensitized solar cells (DSC). A theoretical model has been elaborated, to interpret the frequency response of the device. The high-frequency feature is attributed to the charge transfer at the counter electrode while the response in the intermediate-frequency region is associated with the electron transport in the mesoscopic TiO2 film and the back reaction at the TiO2/electrolyte interface. The low-frequency region reflects the diffusion in the electrolyte. Using an appropriate equivalent circuit, the electron transport rate and electron lifetime in the mesoscopic film have been derived, which agree with the values derived from transient photocurrent and photovoltage measurements. The EIS measurements show that DSC performance variations under prolonged thermal aging result mainly from the decrease in the lifetime of the conduction band electron in the TiO2 film. PMID:16852893

Wang, Qing; Moser, Jacques-E; Grätzel, Michael

2005-08-11

419

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

PubMed

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

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

2013-06-14

420

Towards efficient photoinduced charge separation in carbon nanodots and TiO2 composites in the visible region.  

PubMed

In this work, photoinduced charge separation behaviors in non-long-chain-molecule-functionalized carbon nanodots (CDs) with visible intrinsic absorption (CDs-V) and TiO2 composites were investigated. Efficient photoinduced electron injection from CDs-V to TiO2 with a rate of 8.8 × 10(8) s(-1) and efficiency of 91% was achieved in the CDs-V/TiO2 composites. The CDs-V/TiO2 composites exhibited excellent photocatalytic activity under visible light irradiation, superior to pure TiO2 and the CDs with the main absorption band in the ultraviolet region and TiO2 composites, which indicated that visible photoinduced electrons and holes in such CDs-V/TiO2 composites could be effectively separated. The incident photon-to-current conversion efficiency (IPCE) results for the CD-sensitized TiO2 solar cells also agreed with efficient photoinduced charge separation between CDs-V and the TiO2 electrode in the visible range. These results demonstrate that non-long-chain-molecule-functionlized CDs with a visible intrinsic absorption band could be appropriate candidates for photosensitizers and offer a new possibility for the development of a well performing CD-based photovoltaic system. PMID:25721932

Sun, Mingye; Qu, Songnan; Ji, Wenyu; Jing, Pengtao; Li, Di; Qin, Li; Cao, Junsheng; Zhang, Hong; Zhao, Jialong; Shen, Dezhen

2015-03-11

421

The effect of TiCl4 treatment on the efficiency of dye sensitized solar cell  

NASA Astrophysics Data System (ADS)

Dye sensitized solar cells (DSSC) are the new generation of solar cells that have their advantages such as transparency, flexibility and low cost pro