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1

DOI: 10.1002/asia.201200349 Dye-Sensitized TiO2 Nanotube Solar Cells: Rational Structural and Surface  

E-print Network

the power conversion efficiency of dye-sensitized TiO2 nanotube solar cells. Keywords: dye-sensitized solar efficiency of dye-sensitized TiO2 NT solar cells remained relatively low as a result of incomplete coverageDOI: 10.1002/asia.201200349 Dye-Sensitized TiO2 Nanotube Solar Cells: Rational Structural

Lin, Zhiqun

2

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

E-print Network

, and power conversion efficiency of the hybrid solar cell using highly oriented TiO2 nanotubes were 646 mV, 9 hybrid solar cells reported in literature. The enhancement of the power conversion efficiency could for the efficient electron transfer in hybrid solar cells. Introduction The widespread use of inorganic solar cells

Cao, Guozhong

3

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

4

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

Microsoft Academic Search

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

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

2010-01-01

5

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

6

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

7

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

NASA Astrophysics Data System (ADS)

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

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

2014-10-01

8

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

NASA Astrophysics Data System (ADS)

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

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

2014-01-01

9

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

NASA Astrophysics Data System (ADS)

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

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

2010-10-01

10

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

11

The origin of open circuit voltage of porphyrin-sensitised TiO(2) solar cells.  

PubMed

Electron lifetime and diffusion coefficient measurements in highly efficient porphyrin-sensitised TiO(2) solar cells showed reduced electron lifetime, and consequently, lower photo-induced electron density under illumination compared to commonly used ruthenium dye (N719)-sensitised solar cells, which is proposed to be the origin of the generally lower open circuit voltage. PMID:18830478

Mozer, Attila J; Wagner, Pawel; Officer, David L; Wallace, Gordon G; Campbell, Wayne M; Miyashita, Masanori; Sunahara, Kenji; Mori, Shogo

2008-10-21

12

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

NASA Astrophysics Data System (ADS)

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

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

2013-11-01

13

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

Microsoft Academic Search

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

Kyung Hyun Ko; Young Cheol Lee; Young Jin Jung

2005-01-01

14

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

PubMed

Tailoring the architectures of spherical TiO2 aggregates is crucial to obtain superior photovoltaic properties and promote their application in dye-sensitized solar cells (DSSCs). Herein, we synthesized spherical TiO2 aggregates using different building units, including nanocrystallites, nanorods, nanosheets, and nanotubes, via a hydrothermal method, and studied the effect of the building units on the performances of DSSCs. The aggregates assembled by uniform nanosheet and nanotube building units were synthesized with the use of spherical TiO2 nanorod aggregates as titanium sources in an alkaline hydrothermal reaction. Compared with TiO2 nanoparticles, the spherical TiO2 aggregates possess higher surface area, more efficient light scattering ability, and better electron transport properties. Among the four types of spherical TiO2 aggregates; the nanorod, nanotube, and nanosheet aggregates demonstrate better electron transport properties than the nanocrystallite aggregates; the nanotube and nanosheet aggregates exhibit more efficient light scattering than the nanocrystallite and nanorod aggregates; and the nanotube aggregates show the highest surface area. Thus the DSSC based on nanotube aggregates exhibited the highest energy conversion efficiency of 7.48%, which is 16.0%, 9.7%, and 19.5% higher than those of the DSSCs based on the nanosheet, nanorod, and nanocrystallite aggregates, respectively. PMID:23892684

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

2013-09-01

15

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

PubMed

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

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

2007-01-18

16

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

NASA Astrophysics Data System (ADS)

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

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

2012-06-01

17

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

PubMed

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

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

2014-02-01

18

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

PubMed

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

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

2014-07-01

19

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

20

Preparation of Multilayer TiO2 Thin Films for Dye-Sensitized Solar Cells  

NASA Astrophysics Data System (ADS)

We adopt TiO2 materials with three different morphologies to fabricate multilayer thin films for dye-sensitized solar cell (DSSC) photoelectrodes. The three different TiO2 morphologies are (1) titania nanotubes (Tnt) hydrothermally fabricated by 550 °C calcinating treatment to form an anatase phase (Tnt-C550), (2) TiO2 nanoparticles (H200) prepared by subjecting Tnt to two cycles of hydrothermal treatment, and (3) a TiO2 nanofluid (SF) fabricated by our developed submerged arc nanofluids synthesis system (SANSS). Experimental results showed that DSSCs fabricated with Tnt photoelectrodes tested with AM 1.5 light to simulate sunlight (100 mW/cm2) had a photoelectric conversion efficiency of 2.84%. The thin-film photoelectrode was prepared using Tnt-C550 calcined at 550 °C. Its photoelectric conversion efficiency increased to 5.77%. The photoelectric conversion efficiency of DSSCs with photoelectrodes fabricated using H200 reached 5.91%. Moreover, the photoelectric conversion efficiency of DSSCs with photoelectrodes prepared using SF reached 4.45%. Finally, the TiO2 materials with three different morphologies were used to prepare a three-layer photoelectrode with the structure of H200/Tnt-C550/SF, which was combined with a counter electrode to assemble DSSCs. These DSSCs had a photoelectric conversion efficiency of as high as 7.07%.

Chang, Ho; Chen, Yu-Ling

2010-06-01

21

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

PubMed

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

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

2012-09-28

22

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

23

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

24

Annealing effect on Sb2S3-TiO2 nanostructures for solar cell applications  

NASA Astrophysics Data System (ADS)

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

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

2013-02-01

25

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

26

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

NASA Astrophysics Data System (ADS)

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

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

2013-08-01

27

Non-linear Electron Transport Kinetics in Nanocrystalline TiO(2) Based Solar Cells  

SciTech Connect

An analytical model describing electron transport in dye-sensitized nanocrystalline TiO(2) solar cells is shown to account for the non-linear dependence of the electron transport rate on the electron concentration. Equations relating the influenece of an exponential distribtuion of surface states to electron transport are derived and verified by intensity-modulated photocurrent spectroscopy measurements. A slope of 69 meV is inferred for the surface-state distribution curve.

van de Lagemaat, J.; Frank, A. J.

2000-01-01

28

Properties of dye-sensitized solar cells with TiO2 passivating layers prepared by electron-beam evaporation.  

PubMed

The aim of this work is to prevent back transfer of electrons due to direct contact between the electrolyte and the FTO glass substrate using a TiO2 passivating layer. The TiO2 passivating layer was deposited on FTO glass by e-beam evaporation. The TiO2 film was prepared with different deposition rates. The specific surface area was reduced with increasing deposition rate. The nanoporous TiO2 upper layer was coated by screen-printing on the TiO2 passivating layer prepared by e-beam evaporation. The optical transmittance and absorbance of the TiO2 films depend on the morphology of the TiO2 passivating layer. The dye-sensitized solar cells influenced the surface morphology of the TiO2 passivating layer. The dye-sensitized solar cell using the TiO2 passivating layer recorded a maximum conversion efficiency of 4.93% due to effective prevention of the electron recombination to the electrolyte. PMID:22524036

Jin, Young Sam; Choi, Hyung Wook

2012-01-01

29

Enhanced efficiency of dye-sensitized TiO2 solar cells (DSSC) by doping of metal ions.  

PubMed

Doped TiO(2) semiconductor powders were synthesized using Al and W as photovoltaic property-enhancing impurities. Al-doped TiO(2) electrodes increased open-circuit voltage (V(oc)), but reduced short-circuit current (I(sc)). In contrast, W-doped TiO(2) had an opposite effect. However, dye-sensitized solar cell efficiency fabricated with doped TiO(2) was remarkably better than that of undoped TiO(2). It seems that these phenomena were related to electrical surface-state modifications induced by metal-ion dopants. These modifications led to significant changes in powder aggregation, charge transfer kinetics, and dye adsorption characteristics. The highest efficiency was found by using (Al+W)-doped TiO(2) nanopowders. PMID:15721923

Ko, Kyung Hyun; Lee, Young Cheol; Jung, Young Jin

2005-03-15

30

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

31

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

E-print Network

19.2% Efficient InP Heterojunction Solar Cell with Electron-Selective TiO2 Contact Xingtian Yin *S Supporting Information ABSTRACT: We demonstrate an InP heterojunction solar cell employing hole contact for n-type silicon solar cells, enabling a high open-circuit voltage of 711 m

Javey, Ali

32

Quantitative electron tomography investigation of a TiO2 based solar cell photoanode  

NASA Astrophysics Data System (ADS)

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

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

2014-06-01

33

Self-assembled chromophores within mesoporous nanocrystalline TiO2: towards biomimetic solar cells.  

PubMed

Artificial light-harvesting antennas consisting of self-assembled chromophores that mimic the natural pigments of photosynthetic bacteria have been inserted into voids induced in porous titania (TiO2, anatase) in order to investigate their suitability for hybrid solar cells. Mesoporous nanocrystalline TiO2 with additional uniform macropores was treated with precursor solutions of the pigment which was then induced to self-assemble within the voids. The chromophores were tailored to combine the self-assembly characteristics of the natural bacteriochlorophylls with the robustness of artificial Zn-porphyrins being stable for prolonged periods even upon heating to over 200 degrees C. They assemble on the TiO2 surface to form nano- to micro-crystalline structures with lengths from tens of nm up to several microm and show a photosensitization effect which is supposed to be dependent on the assembly size. The natural examples of these antennas are found in green sulfur bacteria which are able to use photosynthesis in deep water regions with minute light intensities. The implementation of biomimetic antennas for light harvesting and a better photon management may lead to a rise in efficiency of dye-sensitized solar cells also under low light illumination conditions. PMID:19504907

Marek, Peter L; Sieger, Hermann; Scherer, Torsten; Hahn, Horst; Balaban, Teodor Silviu

2009-06-01

34

Effects of Electrospun TiO2 Nanowires Mixed in Nanoparticle-Based Electrode for Dye-Sensitized Solar Cells  

NASA Astrophysics Data System (ADS)

In this article, we report the improvement of energy conversion efficiency by a simple process for dye-sensitized solar cells (DSSCs). Some previous studies were reported in which TiO2 nanowires were used in the place of TiO2 nanoparticles as a TiO2 electrode because nanowires possess a good electron transport property. However, if larger sizes of nanowires are used for the TiO2 electrode, a large void between nanowires and a decrease in surface area are observed. To solve this problem, we report a TiO2 nanoparticle/nanowire hybrid electrode for DSSCs, which showed both a good electron transport property and dye adsorption. TiO2 nanofibers were fabricated by an electrospinning method and sol-gel techniques. TiO2 nanowires, whose diameters were controlled by varying the polymer concentration in the electrospinning solution, were successfully applied to DSSCs. We examine how TiO2 nanowires can work in the TiO2 electrode. In this study, we demonstrated that this hybrid electrode has an advantage in the efficiency of DSSCs.

Shimada, Chieko; Kitamura, Koji; Shiratori, Seimei

2012-04-01

35

Aggregated TiO2 Based Nanotubes for Dye Sensitized Solar Cells  

SciTech Connect

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

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

2013-11-01

36

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

NASA Astrophysics Data System (ADS)

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

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

2009-08-01

37

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

38

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

PubMed

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

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

2010-11-01

39

Nb doping of TiO2 nanotubes for an enhanced efficiency of dye-sensitized solar cells.  

PubMed

Nb-doped TiO(2) nanotube (with C(Nb) < 1 wt%) layers were successfully fabricated by self-ordered electrochemical anodization of Ti-Nb alloys. When used in dye-sensitized solar cells the efficiency enhanced by up to 30% compared to non-doped TiO(2) nanotubes. IMVS measurements indicate the beneficial effect to be due to lower recombination losses. PMID:21184009

Yang, Min; Kim, Doohun; Jha, Himendra; Lee, Kiyoung; Paul, Jonathan; Schmuki, Patrik

2011-02-21

40

Fruit extracts and ruthenium polypyridinic dyes for sensitization of TiO 2 in photoelectrochemical solar cells  

Microsoft Academic Search

Dye-sensitization of nanocrystalline n-type TiO2 was achieved by using fruit extracts as a natural source of sensitizers. Fresh extracts of chaste tree fruit (“maria-preta”, Solanum americanum, Mill.), mulberry (“amora”, Morus alba, L.) and cabbage-palm fruit (“aça??”, Euterpe oleracea, Mart) were employed as TiO2 sensitizers in thin-layer sandwich-type photoelectrochemical solar cells. Conversion of visible light into electricity was accomplished with natural

Christian Graziani Garcia; André Sarto Polo; Neyde Yukie Murakami Iha

2003-01-01

41

Effect of additives on the photovoltaic performance of coumarin-dye-sensitized nanocrystalline TiO2 solar cells.  

PubMed

The effects of deoxycholic acid (DCA) and 4-tert-butylpyridine (TBP) as additives on the photovoltaic performance of coumarin-dye-sensitized nanocrystalline TiO2 solar cells were investigated. DCA coadsorption improved both the photocurrent and photovoltage of the solar cells, even though it decreased the amount of dye adsorbed on the TiO2 electrode. The improved photocurrent may arise from suppression of the deactivation of the excited state via quenching processes between dye molecules or a more negative LUMO level of the dye in the presence of DCA, resulting in a high electron-injection yield from the dye into TiO2. The increased photovoltage is probably due to suppression of recombination between the injected electrons and I3- ions on the TiO2 surface (dark current). The addition of TBP to the electrolyte also markedly improved the photovoltage and fill factor of the solar cell, and consequently, the total conversion efficiency increased from 3.6% to 7.5%. FT-IR spectroscopy indicated that a large amount of TBP was adsorbed on the dye-coated TiO2 films in the presence of Li cations. This result suggests that TBP, like DCA, suppressed the dark current on the TiO2 surface, which resulted in the improved photovoltage. PMID:15969418

Hara, Kohjiro; Dan-oh, Yasufumi; Kasada, Chiaki; Ohga, Yasuyo; Shinpo, Akira; Suga, Sadaharu; Sayama, Kazuhiro; Arakawa, Hironori

2004-05-11

42

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

43

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

PubMed

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

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

2014-11-26

44

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

NASA Astrophysics Data System (ADS)

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

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

2011-02-01

45

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

PubMed Central

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

2014-01-01

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

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

48

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

NASA Astrophysics Data System (ADS)

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

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

2013-10-01

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

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

51

Effects of boron doping in TiO2 nanotubes and the performance of dye-sensitized solar cells  

NASA Astrophysics Data System (ADS)

Titanium nanotubes doped with boron used as the photoelectrode for dye-sensitized solar cells were investigated. The materials were characterized by SEM, XRD, and UV-vis spectroscopy and their photoconversion efficiencies were evaluated. The chemical compositions of TiO2 nanotubes (TNA) and boron doped TNA (B-TNA) were identified by the energy dispersive X-ray spectroscopy (EDS). XRD evidenced the presence of anatase as the main phase and presented the existence of boron elements at interstitial sites between the TiO2 lattices. The UV-vis spectra indicated the narrowing of band gap upon doping boron into titanium nanotubes. The photovoltaic properties were measured by a current-voltage meter under AM1.5 simulated light radiation. The boron-doped TiO2 nanotube arrays showed an enhanced performance with a photocurrent density of 7.85 ± 0.20 mA/cm2 and an overall conversion efficiency (?) of 3.44 ± 0.10%. The enhanced performance was attributed to the enhanced electron injection rate and retardation of the charge recombination, which could be due to perfect matching between the LUMO of dye molecules and the conduction band of TiO2. Electrochemical impedance spectroscopy (EIS) measurement indicated the longer electron lifetime and reduced TiO2/dye/electrolyte interface resistance for boron doped TiO2 nanotubes than that of undoped TiO2 nanotubes.

Subramanian, Alagesan; Wang, Hong-Wen

2012-06-01

52

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

PubMed

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

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

2012-07-01

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

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

NASA Astrophysics Data System (ADS)

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

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

2014-04-01

55

Tunable TiO2 Nanotubes as Nanotemplate for Solar Cells  

NASA Astrophysics Data System (ADS)

Titanium oxide (TiO2) is an n-type semiconductor with a bandgap energy of 3.0-3.2 eV. It has broad applications, because of the versatile functionalities. Synthesis of anodic titanium oxide (ATO) nanotube templates has gained significant progress in fluoride-ion-contained electrolytes. The one-dimensional (1D) structure provides a large specific surface area as well as a direct pathway for charge transport, thus rendering superior capabilities in lightharvesting, electrochromic switching, environmental sensing, energy storage, etc. In this work, highly ordered ATO nanotubes film has been synthesized by two-step anodization method. After using a reductive doping approach, the metal materials (Cu and Ni) can be electrodeposited into the nanotubes. The versatile process yields reproducible tubular structures in ATO nanotubes due to the conductive nature of crystallized TiO2, indicating great potential for nanotemplate application. A dye-sensitized solar cell is also demonstrated by employing the ATO films. It is observed that bottom treatment greatly enhances short current density and filling factor resulting in improved energy conversion efficiency.

Lu, Jia; Li, Dongdong

2011-03-01

56

TiO2 nanotubes infiltrated with nanoparticles for dye sensitized solar cells.  

PubMed

We present a detailed study of the infiltration of titanium dioxide (TiO(2)) nanotubes (NTs) with TiO(2) nanoparticles (NPs) for dye sensitized solar cells (DSSCs). The aim is to combine the merits of the NP's high dye loading and high light harvesting capability with the NT's straight carrier transport path and high electron collection efficiency to improve the DSSC performance. On infiltrating NTs with TiCl(4) solution followed by hydrothermal synthesis, 10 nm size NPs were observed to form a conformal and dense layer on the NT walls. Compared with the bare NT structure, dye loading of this mixed NT and NP structure is more than doubled. The overall photon conversion efficiencies of the fabricated DSSCs are improved by 152%, 107%, and 49% for 8, 13, and 20 µm long NTs, respectively. Electron transport and recombination parameters were extracted based on electrochemical impedance spectroscopy measurements. Although a slight reduction of electron lifetime was observed in the mixed structures due to enhanced recombination with a larger surface area, the diffusion length is still significantly longer than the NT length used, suggesting that most electrons are collected. In addition to dye loading and hence photocurrent increment, the photovoltage and filling factor were also improved in the mixed structure due to a low serial resistance, leading to the enhancement of the overall efficiency. PMID:21474874

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

2011-06-10

57

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

58

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

NASA Astrophysics Data System (ADS)

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

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

2014-03-01

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 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

61

Structural control of hierarchically-ordered TiO2 films by water for dye-sensitized solar cells.  

PubMed

A facile way of controlling the structure of TiO(2) by changing the amount of water to improve the efficiency of dye-sensitized solar cells (DSSCs) is reported. Hierarchically ordered TiO(2) films with high porosity and good interconnectivity are synthesized in a well-defined morphological confinement arising from a one-step self-assembly of preformed TiO(2) (pre-TiO(2)) nanocrystals and a graft copolymer, namely poly(vinyl chloride)-g-poly(oxyethylene methacrylate). The polymer-solvent interactions in solution, which are tuned by the amount of water, are shown to be a decisive factor in determining TiO(2) morphology and device performance. Systematic control of wall and pore size is achieved and enables the bifunctionality of excellent light scattering properties and easy electron transport through the film. These properties are characterized by reflectance spectroscopy, incident photon-to-electron conversion efficiency, and electrochemical impedance spectroscopy analyses. The TiO(2) photoanode that is prepared with a higher water ratio, [pre-TiO(2)]:[H(2)O]=1:0.3, shows a larger surface area, greater light scattering, and better electron transport, which result in a high efficiency (7.7?%) DSSC with a solid polymerized ionic liquid. This efficiency is much greater than that of commercially available TiO(2) paste (4.0?%). PMID:24816729

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

2014-06-23

62

Performance comparison of dye-sensitized solar cells by using different metal oxide- coated TiO2 as the photoanode  

NASA Astrophysics Data System (ADS)

In order to increase the conversion efficiency of dye-sensitized solar cells, TiO2 photoanode surface is often covered with a metal oxide layer to form a core-shell composite structure. Different metal oxide coating on TiO2 as composite photoanodes can affect the cell efficiency variously. However, there still lacks the crosswise comparison among the effects of different metal oxides on TiO2 photoanode. In this study, TiO2 was coated with Al2O3, CaO, ZnO, MgO, Fe2O3 or Bi2O3 separately by liquid phase deposition method. The results indicated that cells with TiO2/Al2O3, TiO2/ZnO, TiO2/CaO, or TiO2/MgO composite film as a photoanode had higher conversion efficiency than those with un-coated TiO2 films. TiO2/Al2O3 showed the highest efficiency and TiO2/CaO ranked second. On the contrary, cells with TiO2/Bi2O3 or TiO2/Fe2O3 composite film as a photoanode had lower conversion efficiency than those with un-coated TiO2 films. The mechanism of the cell efficiency change was also investigated. To get higher conversion efficiency, matched energy level of the metal oxide with TiO2 is the first prerequisite, and then the optimum coating thickness is also a necessary condition.

Xuhui, Sun; Xinglan, Chang; Wanquan, Tuo; Dong, Wang; Kefei, Li

2014-03-01

63

An unconventional route to high-efficiency dye-sensitized solar cells via embedding graphitic thin films into TiO2 nanoparticle photoanode.  

PubMed

Graphitic thin films embedded with highly dispersed titanium dioxide (TiO(2)) nanoparticles were incorporated for the first time into the conventional dye-sensitized solar cells (DSSCs), resulting in a remarkably improved cell efficiency due to its superior electron conductivity. Massively ordered arrays of TiO(2) dots embedded in carbon matrix were fabricated via UV-stabilization of polystyrene-block-poly(4-vinylpyridine) films containing TiO(2) precursors followed by direct carbonization. For dye-sensitized TiO(2) based solar cells containing carbon/TiO(2) thin layers at both sides of pristine TiO(2) layer, an increase of 62.3% [corrected] in overall power conversion efficiency was achieved compared with neat TiO(2)-based DSSCs. Such a remarkably improved cell efficiency was ascribed to the superior electron conductivity and extended electron lifetime elucidated by cyclic voltammetry and impedance spectroscopy. PMID:22148913

Jang, Yoon Hee; Xin, Xukai; Byun, Myunghwan; Jang, Yu Jin; Lin, Zhiqun; Kim, Dong Ha

2012-01-11

64

Improved Performance of Solid-State Dye-Sensitized Solar Cells with CuI: Structure Control of Porous TiO2 Films  

NASA Astrophysics Data System (ADS)

By increasing the pore and particle size of porous TiO2 films, the photovoltaic properties of solid-state dye-sensitized solar cells were dramatically improved. We analyzed the relation between the photovoltaic property and the microstructure of TiO2/Dye/CuI measured by scanning electron microscopy of the cross section of the cells. The larger pore size of the TiO2 films improved the CuI filling and the high degree of filling improved the short-circuit current density. Multilayered TiO2 films consisting of a TiO2 layer with small TiO2 particles and a second layer with larger TiO2 particles gave a power conversion efficiency under 1 sun of 6.0%.

Moribe, Shinya; Takeichi, Akihiro; Seki, Juntaro; Kato, Naohiko; Higuchi, Kazuo; Ueyama, Koji; Mizumoto, Katsuyoshi; Toyoda, Tatsuo

2012-11-01

65

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

Microsoft Academic Search

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

Janne Halme; Jaakko Saarinen; Peter Lund

2006-01-01

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

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

PubMed

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

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

2010-07-01

68

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

69

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

NASA Astrophysics Data System (ADS)

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

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

2014-09-01

70

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

NASA Astrophysics Data System (ADS)

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

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

2014-10-01

71

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

72

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

NASA Astrophysics Data System (ADS)

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

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

2013-12-01

73

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

NASA Astrophysics Data System (ADS)

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

Shen, Qing; Toyoda, Taro

74

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

75

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

2015-02-01

76

Dye-sensitized solar cells based on TiO2 nanoparticles/nanobelts double-layered film with improved photovoltaic performance  

NASA Astrophysics Data System (ADS)

Dye-sensitized solar cells (DSSCs) were fabricated using double layers of nano-structured TiO2 films as photoanodes. Different anode architectures of double-layered TiO2 films were fabricated in order to study the structural effect of photoanodes on the solar cell efficiency. The performances of DSSCs based on composite photoanodes in the forms of TiO2 nanoparticles/nanobelts (TiO2 P-B), TiO2 nanoparticles/nanoparticles (TiO2 P-P), TiO2 nanobelts/nanobelts (TiO2 B-B) double-layered electrodes with the same film thicknesses were studied in detail, and their corresponding efficiencies were 4.81%, 3.55% and 0.36%. The work shows that significant improvement of efficiency can be achieved through combined enhancement in optical scattering using the TiO2 nanobelts and high dye absorbing capacity of the TiO2 nanoparticles.

Fan, Jiajie; Li, Zhenzhen; Zhou, Wenyuan; Miao, Yucong; Zhang, Yaojia; Hu, Junhua; Shao, Guosheng

2014-11-01

77

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

PubMed

Crack-free TiO(2) nanotube (NT) membranes were obtained by short time re-anodization of a sintered TiO(2) NT array on Ti foil, followed by dilute HF etching at room temperature. The resulting freestanding TiO(2) membranes were opaque with a slight yellow color having one end open and another end closed. The membranes were then fixed on transparent fluorine-tin-oxide glass using a thin layer of screen-printed TiO(2) nanoparticles (NPs) as a binding medium. It was found that low temperature treatment of the resulting NT/NP film under appropriate pressure before sintering at 450?°C was critical for successful fixation of the NT membrane on the NP layer. The resulting films with open-ends of NT membranes facing the NP layer (open-ends down, OED, configuration) exhibited better interfacial contact between NTs and NPs than those with closed-ends facing the NP layer (closed-ends down, CED, configuration). The cells with an OED configuration exhibit higher external quantum efficiency, greater charge transfer resistance from FTO/TiO(2) to electrolyte, and better dye loading compared to CED configurations. The solar cells with the OED configuration gave 6.1% energy conversion efficiency under AM1.5G condition when the commercial N719 was used as a dye and I(-)/I(3)(-) as a redox couple, showing the promise of this method for high efficiency solar cells. PMID:21625043

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

2011-07-15

78

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

NASA Astrophysics Data System (ADS)

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

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

2013-02-01

79

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

NASA Astrophysics Data System (ADS)

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

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

2011-06-01

80

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

81

One-step growth of well-aligned TiO2 nanorod arrays for flexible dye-sensitized solar cells.  

PubMed

We present here the feasibility of growing well-aligned TiO2 nanorod arrays by a dc reactive magnetron sputtering strategy for flexible dye-sensitized solar cells. These flexible devices yield an efficiency of 5.3% in comparison to 1.2% from traditional TiO2 nanoparticles by a low-temperature technique. PMID:25531300

Chen, Xiaoxu; Tang, Qunwei; Zhao, Zhiyuan; Wang, Xinghui; He, Benlin; Yu, Liangmin

2015-01-20

82

Effect of hot-pressing on an electrospun TiO2 electrode for dye-sensitized solar cells  

NASA Astrophysics Data System (ADS)

A hot-pressing process is shown to enhance the adhesion of TiO2 nanofibers electrospun onto fluorine-doped tin oxide substrates for use in dye-sensitized solar cells. By using the resulting electrochemical impedance spectroscopic characteristics, the application of 7, 14, and 21 MPa of pressure was found to result in calculated lifetimes of 7.48, 15.13, and 13.74 ms, respectively. From the results of a thermogravimetric analysis, a stepped heat treatment was developed for calcination of the hot-pressed TiO2 electrodes. Hot-pressing at 14 MPa and 100 °C yielded the dye-sensitized solar cell with the highest energy conversion efficiency.

Kim, Jeong-Hwa; Sung, Shi-Joon; Kim, Kang-Pil; Hwang, Dae-Kue

2014-07-01

83

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

Microsoft Academic Search

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

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

2009-01-01

84

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

Microsoft Academic Search

This study investigated the relationship of anthocyanin concentration from different organic fruit species and output voltage and current in a TiO2 dye-sensitized solar cell (DSSC) and hypothesized that fruits with greater anthocyanin concentration produce higher maximum power point (MPP) which would lead to higher current and voltage. Anthocyanin dye solution was made with crushing of a group of fresh fruits

Radin Ahmadian

2010-01-01

85

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

NASA Astrophysics Data System (ADS)

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

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

2006-12-01

86

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

87

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

88

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

89

Bilayer inverse opal TiO2 electrodes for dye-sensitized solar cells via post-treatment.  

PubMed

We investigated the formation of bilayer inverse opal TiO(2) (io-TiO(2)) structures via post-treatment with a TiO(2) precursor solution and characterized the photovoltaic performances of the resulting electrodes for use in dye-sensitized solar cells. The post-treatment of TiO(2) inverse opals in a precursor solution grew rutile TiO(2) nanoparticles on anatase crystalline phase io-TiO(2) surfaces, resulting in anatase/rutile bilayer structures. We achieved a maximum photovoltaic conversion efficiency of 4.6% using a 25 ?m thick electrode formed with the post-treated io-TiO(2) under simulated AM 1.5 light. This efficiency represents a 183% improvement over the non-post-treated io-TiO(2) electrodes. The shell thickness was controlled by the post-treatment time. The effects of shell thickness on photovoltaic performance were investigated by measuring the morphologies and electrochemical impedance of the post-treated io-TiO(2). We found that post-treatment up to a certain period of time increased the surface area and electron lifetime, but further treatment resulted in decreased area and saturated lifetimes. The optimal post-treatment time was identified, and the optimal io-TiO(2) electrodes were characterized. PMID:21488619

Shin, Ju-Hwan; Moon, Jun Hyuk

2011-05-17

90

Optimization of paste formulation for TiO 2 nanoparticles with wide range of size distribution for its application in dye sensitized solar cells  

Microsoft Academic Search

Dye sensitized solar cell (DSSC) can be an economically viable and technically simpler alternate to the silicon based solar cells. Films of nanocrystalline titanium dioxide (TiO2) are considered as the most suitable photoelectrode for DSSC. For this study, TiO2 powder of anatase phase, synthesized in acidic environment was used. The average diameter of the nanoparticles was ?20 nm and BET surface

Suresh Kumar Dhungel; Jesse G. Park

2010-01-01

91

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

Microsoft Academic Search

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

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

2009-01-01

92

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

PubMed

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

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

2013-09-21

93

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

PubMed

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

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

2014-02-01

94

Preparations and Characterizations of TiO2 Pastes for Flexible Dye-Sensitized Solar Cells  

Microsoft Academic Search

New TiO2 pastes for the fabrication of TiO2 electrodes at low temperature were prepared from a TiO2 nanoparticle colloidal solution including Ti-alkoxide precursors. In addition, TiO2 pastes comprising 123 nm and 200 nm TiO2 particles used as scattering particles were prepared. Single and double layered TiO2 electrodes were deposited onto an ITO-PEN film by the doctor-blade method and subsequently sintered at 140°C

Young-Wook Jang; Young-Keun Kim; Hyun-Woo Park; Du-Hyun Won; Sang-Eun Cho; Won-Pill Hwang; Ki-Suck Jung; Mi-Ra Kim; Jin-Kook Lee

2011-01-01

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

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

97

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

98

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

NASA Astrophysics Data System (ADS)

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

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

2013-01-01

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

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

2014-11-14

101

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

NASA Astrophysics Data System (ADS)

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

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

2014-02-01

102

Hydrothermal synthesis of a crystalline rutile TiO2 nanorod based network for efficient dye-sensitized solar cells.  

PubMed

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

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

2013-09-27

103

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

PubMed

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

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

2006-02-23

104

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

PubMed

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

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

2013-10-18

105

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

NASA Astrophysics Data System (ADS)

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

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

2013-10-01

106

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

SciTech Connect

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

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

2000-01-01

107

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

NASA Astrophysics Data System (ADS)

The rutile TiO2 nanorods (RTNs) with the length of 40-130 nm and diameters approximately 8-15 nm, containing some 300-500 nm sized RTN aggregates and 6% of anatase TiO2 nanocrystals, were prepared by surfactant-assisted hydrothermal method. The dye-sensitized solar cell (DSC) based on the RTNs exhibited power conversion efficiency of 6.03%. As compared to P25 TiO2 based DSC, RTNs based DSC shows improved light-harvesting and Brunauer-Emmett-Teller surface area, leading to an increase in short-circuit current (Jsc) by 40.6%.

Yang, Weiguang; Wan, Farong; Wang, Yali; Jiang, Chunhua

2009-09-01

108

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

109

Study on electrical and optical properties of nanocomposited MEH-PPV: TiO2 thin film for hybrid solar cells  

Microsoft Academic Search

The performance of nanocomposited poly [2-methoxy-5-(2-ethylhexyloxy-p-phenylene-vinylene] (MEH-PPV) and titanium dioxide (TiO2) thin film for hybrid solar cells application has been investigated. The nanocomposited MEH-PPV:TiO2 thin film has been prepared on glass substrate using spin-coating deposition method at different composition (wt %) of TiO2 nanoparticle from 5 to 15 wt% at room temperature. The electrical conductivities of nanocomposited thin films were

F. S. S. Zahid; M. S. P. Sarah; M. Rusop

2011-01-01

110

Mesoporous TiO2 beads for high efficiency CdS/ CdSe quantum dot co-sensitized solar cells  

E-print Network

Mesoporous TiO2 beads for high efficiency CdS/ CdSe quantum dot co-sensitized solar cells Ru Zhou consisting of packed TiO2 nanocrystallites. A power conversion efficiency up to 4.05% has been achieved,9,10,25­27 However, the power conversion efficiency of these QDSCs, typically with the efficiency of 15%, still lags

Cao, Guozhong

111

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

Microsoft Academic Search

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

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

2011-01-01

112

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 and storage efficiency for this system is 0.82%. Such an integrated power pack could serve as a power source

Wang, Zhong L.

113

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

114

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

115

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

116

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

PubMed

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

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

2014-04-21

117

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

NASA Astrophysics Data System (ADS)

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

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

2014-04-01

118

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

Microsoft Academic Search

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

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

2012-01-01

119

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

PubMed

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

Hossain, Md Faruk; Takahashi, Takakazu

2011-04-01

120

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

121

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

122

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

NASA Astrophysics Data System (ADS)

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

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

2013-02-01

123

Efficiency enhancement of dye-sensitized solar cells by the addition of an oxidizing agent to the TiO(2) paste.  

PubMed

The addition of various amounts of a strong oxidizing agent (3,5-dinitrosalicyclic acid, DNSA) to TiO2 paste enhances the solar-to-electrical-energy conversion efficiency of the corresponding dye-sensitized solar cells (DSSCs). Maximum performance was obtained from a device that was fabricated by using a TiO2 paste with 2?wt?% DNSA, which showed a short-circuit current density of 17.88?mA?cm(-2) , an open-circuit voltage of 0.78?V, and an overall conversion efficiency of 9.62?%, which was an improvement in comparison to reference cells without DNSA. This improvement was rationalized in terms of the amount of residual carbon (formed due to the oxidation of binders) remaining on the TiO2 surface. Addition of a larger amount of oxidizing agent led to a smaller amount of residual carbon on the TiO2 surface. This smaller amount of residual carbon enhanced the adsorption of a larger number of dye molecules on the TiO2 surface. The addition of an oxidizing agent facilitated the removal of more residual organic species during the high-temperature calcination process while causing no change in the surface morphology and microstructure of the TiO2 film. PMID:24106168

Ko, Kwan-Woo; Lee, Minoh; Sekhon, S S; Balasingam, Suresh Kannan; Han, Chi-Hwan; Jun, Yongseok

2013-11-01

124

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

125

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

NASA Astrophysics Data System (ADS)

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

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

2012-08-01

126

Enhanced performance of dye-sensitized solar cells based on TiO2 nanotube membranes using an optimized annealing profile.  

PubMed

We use free-standing TiO2 nanotube membranes that are transferred onto FTO slides in front-side illuminated dye-sensitized solar cells (DSSCs). We investigate the key parameters for solar cell arrangement of self-ordered anodic TiO2 nanotube layers on the FTO substrate, namely the influence of the annealing procedure on the DSSC light conversion efficiency. The results show that using an optimal temperature annealing profile can significantly enhance the DSSC efficiency (in our case ? = 9.8%), as it leads to a markedly lower density of trapping states in the tube oxide, and thus to strongly improved electron transport properties. PMID:25504216

Mohammadpour, F; Moradi, M; Lee, K; Cha, G; So, S; Kahnt, A; Guldi, D M; Altomare, M; Schmuki, P

2015-01-15

127

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

NASA Astrophysics Data System (ADS)

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

Abdullah, M. H.; Rusop, M.

2013-11-01

128

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

129

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

PubMed Central

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

2013-01-01

130

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

NASA Astrophysics Data System (ADS)

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

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

2010-03-01

131

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

PubMed

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

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

2006-02-01

132

Anatase TiO2 with nanopores for dye-sensitized solar cells.  

PubMed

In this paper, a series of mesoporous anatase TiO2 crystals were prepared through a hydrothermal method. By using different carboxylic acids as solvents and additives, the morphology of the integral crystals as well as inner pores can be tuned by the chain length of the carboxylic acids. Further application of these anatase TiO2 crystals as the photoanode of DSCs resulted in an overall energy conversion efficiency of 7.55% because of their low electrical resistivity loss and improved light harvesting abilities. PMID:25242088

Yang, Shuang; Zheng, Yi Chu; Hou, Yu; Yang, Xiao Hua; Yang, Hua Gui

2014-11-14

133

Thickness-controllable textured TiO2 underlayer for a flexible dye-sensitized solar cell sub-module  

NASA Astrophysics Data System (ADS)

Incorporating a thin underlayer as a barrier interface between nanocrystalline TiO2 and conducting substrate suppresses recombination loss in dye-sensitized solar cells (DSSCs). The study investigates the effect of the thickness of the textured underlayer on the optical properties, photovoltaic performance, and electron-transporting properties. The photocurrent of the Ti foil-based photoanode exhibits a strong dependence on underlayer thickness. A homogeneous Pt counter electrode with superior catalytic ability is prepared by spraying onto a conducting plastic substrate. A flexible DSSC sub-module using Ti foil-based photoanode with an optimized thickness underlayer, and a plastic substrate counter electrode with sprayed-reduced Pt, has an energy-conversion efficiency of 7.10%.

Lee, Chia-Hua; Lu, Ming-De; Guan, Qiao-Zhi; Tung, Yung-Liang; Tsai, Song-Yeu; Lin, Fu-Ming

2014-04-01

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

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

136

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

137

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

NASA Astrophysics Data System (ADS)

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

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

2014-01-01

138

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

2015-01-20

139

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

NASA Astrophysics Data System (ADS)

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

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

2013-05-01

140

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

E-print Network

, Washington 98195-2120, United States Advanced Material and Technology Institute, University of Science, Xuanhui Qu, and Guozhong Cao*, Department of Materials and Engineering, University of Washington, Seattle cosensitized solar cells. The CdS and CdSe quantum dots were prepared on TiO2 mesoporous film through

Cao, Guozhong

141

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

142

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

E-print Network

-OMeTAD). By depositing ZrO2 films with angstrom-level precision, coating the mesoporous TiO2 produces over a two-OMeTAD interface and passivates localized surface states. Low- frequency negative capacitances, frequently observed to the spiro-OMeTAD. Introduction Dye-sensitized solar cells (DSCs) based on mesoporous titania and liquid

143

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

PubMed

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

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

2011-12-15

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

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

NASA Astrophysics Data System (ADS)

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

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

2006-06-01

146

One-dimensional hierarchical nanostructures of TiO(2) nanosheets on SnO(2) nanotubes for high efficiency solid-state dye-sensitized solar cells.  

PubMed

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

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

2013-09-20

147

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

NASA Astrophysics Data System (ADS)

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

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

2013-03-01

148

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

PubMed

A colloidal crystal-splitting growth regime has been accessed, in which TiO(2) nanocrystals, selectively trapped in the metastable anatase phase, can evolve to anisotropic shapes with tunable hyperbranched topologies over a broad size interval. The synthetic strategy relies on a nonaqueous sol-gel route involving programmed activation of aminolysis and pyrolysis of titanium carboxylate complexes in hot surfactant media via a simple multi-injection reactant delivery technique. Detailed investigations indicate that the branched objects initially formed upon the aminolysis reaction possess a strained monocrystalline skeleton, while their corresponding larger derivatives grown in the subsequent pyrolysis stage accommodate additional arms crystallographically decoupled from the lattice underneath. The complex evolution of the nanoarchitectures is rationalized within the frame of complementary mechanistic arguments. Thermodynamic pathways, determined by the shape-directing effect of the anatase structure and free-energy changes accompanying branching and anisotropic development, are considered to interplay with kinetic processes, related to diffusion-limited, spatially inhomogeneous monomer fluxes, lattice symmetry breaking at transient Ti(5)O(5) domains, and surfactant-induced stabilization. Finally, as a proof of functionality, the fabrication of dye-sensitized solar cells based on thin-film photoelectrodes that incorporate networked branched nanocrystals with intact crystal structure and geometric features is demonstrated. An energy conversion efficiency of 6.2% has been achieved with standard device configuration, which significantly overcomes the best performance ever approached with previously documented prototypes of split TiO(2) nanostructures. Analysis of the relevant photovoltaic parameters reveals that the utilized branched building blocks indeed offer light-harvesting and charge-collecting properties that can overwhelm detrimental electron losses due to recombination and trapping events. PMID:22004553

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

2011-11-30

149

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

PubMed

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

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

2013-09-11

150

Sputtered highly ordered TiO2 nanorod arrays and their applications as the electrode in dye-sensitized solar cells.  

PubMed

For the first time, the TiO2 nanorod arrays have been prepared on ITO substrates at room temperature by dc reactive magnetron sputtering technique. These TiO2 nanorods have a preferred orientation along the (220) direction and are perpendicular to the ITO substrate. Both the X-ray diffraction and Raman scattering measurements show that the highly ordered TiO2 nanorod arrays have an anatase crystal structure. The diameter of the nanorod varies from 30 nm to 100 nm and the nanorod length can be varied from several hundred nanometers to several micrometers depending on the deposition time. The TiO2 nanorod arrays with about 3 micrometers length have been used as an electrode for dye-sensitized solar cell (DSSC). Short-circuit photocurrent density, open-circuit voltage, fill factor and light-to-electricity conversion efficiency at 100 mW/cm2 light intensity are estimated to be 12.76 mA/cm2, 0.65 V, 0.63 and 5.25%, respectively, for the DSSC made of the TiO2 nanorods. PMID:21456121

Meng, Lijian; Ma, Aifeng; Ying, Pinliang; Feng, Zhaochi; Li, Can

2011-02-01

151

Enhanced performance for dye-sensitized solar cells based on spherical TiO2 nanorod-aggregate light-scattering layer  

NASA Astrophysics Data System (ADS)

A new bilayer-structured photoelectrode film with spherical TiO2 nanorod aggregates as a light-scattering overlayer and nanocrystalline TiO2 as an underlayer is fabricated and studied with the aim of improving energy conversion efficiency in dye-sensitized solar cells (DSSCs). An overall energy conversion efficiency of 6.10% and a short-circuit photocurrent density of 18.47 mA cm-2 are achieved by introducing a spherical TiO2 nanorod-aggregate light-scattering layer. These are respectively 37.1% and 42.6% higher than those of a DSSC using a conventional 200 nm-diameter solid TiO2 particle light-scattering layer. These improvements are attributed to the spherical TiO2 nanorod-aggregate overlayer, which has a large surface area for sufficient dye adsorption, sub-micrometer size for efficient light scattering, and lower surface state traps, allowing a longer exciton lifetime.

Liu, Zhao-Hui; Su, Xun-Jia; Hou, Gen-Liang; Bi, Song; Xiao, Zhou; Jia, Hai-Peng

2012-11-01

152

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

PubMed

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

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

2014-03-01

153

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

PubMed

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

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

2013-07-01

154

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

155

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

NASA Astrophysics Data System (ADS)

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

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

2013-01-01

156

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

157

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

PubMed

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

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

2013-06-01

158

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

159

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

Microsoft Academic Search

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

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

2004-01-01

160

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

161

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

PubMed

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

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

2014-08-01

162

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

163

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

PubMed

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

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

2013-01-01

164

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

NASA Astrophysics Data System (ADS)

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

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

2013-06-01

165

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

PubMed Central

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

2013-01-01

166

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

PubMed

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

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

2013-04-24

167

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

168

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

169

Characterization of the TiO2/dye/electrolyte interfaces in dye-sensitized solar cells by means of a titania-binding nitroxide.  

PubMed

Dye-sensitized solar cells (DSSCs) have been characterized in several literature examples by using relatively complex methods and/or modified DSSC conditions with respect to the usual working ones. In this study, we propose a method for the investigation of the interfaces TiO2/dye/electrolyte in a DSSC at its usual working conditions. This method implies the use of a computer-aided analysis of the electron paramagnetic resonance (EPR) spectra of the spin probe 4-carboxy-2,2,6,6-tetramethylpiperidine 1-oxyl (4-carboxy-TEMPO, indicated as 4-cT). This probe well-mimics the dyes in their interactions with TiO2 surface, but does not perturb dye adsorption onto TiO2 surface, as verified by UV-vis measurements. First, we investigated the interacting ability toward 4-cT of commercially available TiO2 used for assembling the DSSC. It was found that interactions are modulated by the different distribution of interacting sites at the solid surface and powder aggregation. Further, experiments on 4-cT were carried out in the presence of a series of other molecules coded as N3, N719, and D149, which are commonly used as dyes in DSSCs. Then, the effect of solutions added to the electrodes was investigated. On the basis of the interactions occurring at the TiO2/dye/electrolyte interfaces, we selected the ingredients of the DSSCs. Electrical and EPR characterizations of these DSSCs miniaturized to enter the EPR cavity, together with time-dependent laser-light on-off experiments, were carried out, which demonstrated the ability of the EPR analysis to monitor the types and strengths of the interactions occurring at the cell's different interfaces. This method using the standard continuous wave EPR technique at room temperature may be profitably used to characterize the quality and performances of a DSSC. PMID:25348929

Fattori, Alberto; Cangiotti, Michela; Fiorani, Luigi; Lucchi, Susanna; Ottaviani, Maria Francesca

2014-11-18

170

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

171

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

SciTech Connect

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

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

2005-11-01

172

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

2015-02-01

173

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

174

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

175

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

176

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

177

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

PubMed Central

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

2012-01-01

178

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

179

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

180

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

PubMed Central

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

2011-01-01

181

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

Microsoft Academic Search

Nanocrystalline TiO2 porous electrodes were prepared by screen-printing method in order to efficiently control the fabrication process. TiO2 viscous pastes were prepared from commercial TiO2 nano powder using ethyl cellulose as a porosity controlling agent. A metal-free organic dye (indoline dye D102) was used as a sensitizer. TiO2 porous electrodes with different thicknesses were investigated. The optical and physical properties

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

2009-01-01

182

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

183

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

NASA Astrophysics Data System (ADS)

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

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

2012-06-01

184

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

185

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

186

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

187

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

PubMed

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

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

2011-09-01

188

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

PubMed

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

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

2012-01-21

189

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

NASA Astrophysics Data System (ADS)

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

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

2013-06-01

190

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

PubMed

We carried out a systematic study on the effect of nanocrystalline TiO2 paste formulations and temperature treatment on the performance of dye solar cells (DSCs) over a large temperature range, to provide useful information for the fabrication of both plastic and metal flexible devices. We compared conventional screen-printable and binder-free TiO2 pastes with a new formulation which includes hydroxylethyl cellulose (HEC), enabling the study of the effect of organic materials in the TiO2 layer in the whole 25-600 °C temperature range. Differently from the binder-free formulations where the device efficiency rose monotonically with temperature, the use of cellulose binders led to remarkably different trends depending on their pyrolysis and decomposition thresholds and solubility, especially at those temperatures compatible with plastic foils. Above 325 °C, where metal foil can be used as substrates, the efficiencies become similar to those of the binder-free paste due to effective binder decomposition and inter-nanoparticle bonding. Finally, we demonstrated, for the first time, that the simultaneous application of both temperature (110-150 °C) and pressure (100 MPa) can lead to a large improvement (33%) compared to the same mechanical compression method carried out at room temperature only. PMID:23727656

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

2013-06-28

191

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

192

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

193

Dye-sensitized solar cells employing doubly or singly open-ended TiO2 nanotube arrays: structural geometry and charge transport.  

PubMed

We systematically investigated the charge transport properties of doubly or singly open-ended TiO2 nanotube arrays (DNT and SNT, respectively) for their utility as electrodes in dye-sensitized solar cells (DSCs). The SNT or DNT arrays were transferred in a bottom-up (B-up) or top-up (T-up) configuration onto a fluorine-doped tin oxide (FTO) substrate onto which had been deposited a 2 ?m thick TiO2 nanoparticle (NP) interlayer. This process yielded four types of DSCs prepared with SNTs (B-up or T-up) or DNT (B-up or T-up). The photovoltaic performances of these DSCs were analyzed by measuring the dependence of the charge transport on the DSC geometry. High resolution scanning electron microscopy techniques were used to characterize the electrode cross sections, and electrochemical impedance spectroscopy was used to characterize the electrical connection at the interface between the NT array and the TiO2 NP interlayer. We examined the effects of decorating the DNT or SNT arrays with small NPs (sNP@DNT and sNP@SNT, respectively) in an effort to increase the extent of dye loading. The DNT arrays decorated with small NPs performed better than the decorated SNT arrays, most likely because the Ti(OH)4 precursor solution flowed freely into the array through the open ends of the NTs in the DNT case but not in the SNT case. The sNP@DNT-based DSC exhibited a better PCE (10%) compared to the sNP@SNT-based DSCs (6.8%) because the electrolyte solution flow was not restricted, direct electron transport though the NT arrays was possible, the electrical connection at the interface between the NT array and the TiO2 NP interlayer was good, and the array provided efficient light harvesting. PMID:25136743

Choi, Jongmin; Song, Seulki; Kang, Gyeongho; Park, Taiho

2014-09-10

194

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

PubMed

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

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

2013-10-01

195

Modified two-step deposition method for high-efficiency TiO2/CH3NH3PbI3 heterojunction solar cells.  

PubMed

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

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

2014-06-25

196

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

PubMed

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

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

2014-11-01

197

MgO-hybridized TiO2 interfacial layers assisting efficiency enhancement of solid-state dye-sensitized solar cells  

NASA Astrophysics Data System (ADS)

Interfacial modification of a thin TiO2 compact layer (T-CL) by hybridization with MgO enhanced the quantum conversion efficiency of solid-state dye-sensitized solar cells (ssDSSCs) comprising a multilayer structure of transparent electrode/T-CL/dye-sensitized mesoporous TiO2/hole conductor/metal counter electrode. The Mg(CH3COO)2 treatment was employed to introduce a MgO-TiO2 CL (T/M-CL), which enhanced the physical connection and conduction between the CL and mesoporous semiconductor layer as a consecutive interface, owing to the dehydration reaction of Mg(CH3COO)2. The photocurrent density of ssDSSC was increased 33% by the T/M-CL compared with the T-CL, using an equivalent amount of adsorbed dye. The ssDSSC with the T/M-CL yielded the highest efficiency of 4.02% under irradiation at 100 mW cm-2. The electrical impedance spectroscopy showed that the charge-transfer resistance (Rct) of the photoelectrode with T/M-CL was reduced by 300 ? from the reference non-treated T-CL electrode. Characterized by the intrinsically low Rct of the compact layer, the T/M-CL is capable of improving the photovoltaic performance of solid-state sensitized mesoscopic solar cells.

Sakai, Nobuya; Ikegami, Masashi; Miyasaka, Tsutomu

2014-02-01

198

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

199

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

NASA Astrophysics Data System (ADS)

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

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

2012-05-01

200

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

PubMed

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. PMID:25484118

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

2014-12-18

201

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

202

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

203

Multifunctional Ag-decorated porous TiO2 nanofibers in dye-sensitized solar cells: efficient light harvesting, light scattering, and electrolyte contact.  

PubMed

Designing the photoanode structure in dye-sensitized solar cells (DSSCs) is vital to realizing enhanced power conversion efficiency (PCE). Herein, novel multifunctional silver-decorated porous titanium dioxide nanofibers (Ag/pTiO2 NFs) made by simple electrospinning, etching, and chemical reduction processes are introduced. The Ag/pTiO2 NFs with a high surface area of 163?m(2) ?g(-1) provided sufficient dye adsorption for light harvesting. Moreover, the approximately 200?nm diameter and rough surface of the Ag/pTiO2 NFs offered enough light scattering, and the enlarged interpores among the NFs in the photoanode also permitted electrolyte circulation. Ag nanoparticles (NPs) were well dispersed on the surface of the TiO2 NFs, which prevented aggregation of the Ag NPs after calcination. Furthermore, a localized surface plasmon resonance effect by the Ag NPs served to increase the light absorption at visible wavelengths. The surface area and amount of Ag NPs was optimized. The PCE of pTiO2 NF-based DSSCs was 27?% higher (from 6.2 to 7.9?%) than for pure TiO2 NFs, whereas the PCE of Ag/pTiO2 NF-based DSSCs increased by about 12?% (from 7.9 to 8.8?%). Thus, the PCE of the multifunctional pTiO2 NFs was improved by 42?%, that is, from 6.2 to 8.8?%. PMID:25138442

Hwang, Sun Hye; Song, Hee; Lee, Jungsup; Jang, Jyongsik

2014-09-26

204

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

PubMed

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

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

2014-06-25

205

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

PubMed

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 (V oc), short-circuit current density (J sc), 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 V oc of 0.6 V, a high J sc 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

Chen, Lung-Chien; Hsu, Chih-Hung; Chan, Po-Shun; Zhang, Xiuyu; Huang, Cing-Jhih

2014-01-01

206

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

207

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

NASA Astrophysics Data System (ADS)

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

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

2014-08-01

208

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

NASA Astrophysics Data System (ADS)

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

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

2014-10-01

209

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

210

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

Microsoft Academic Search

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

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

2010-01-01

211

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

Microsoft Academic Search

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

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

2010-01-01

212

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

213

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

PubMed Central

A single-crystal-like titania nanowire network was successfully synthesized by a surfactant assisted “oriented attachment” mechanism. Highly crystallized titania nanorods have been synthesized by hydrothermal process using block-copolymer F127 with ethylenediamine. It was observed from high resolution TEM image that titanium atoms aligned perfectly in titania anatase structure with no defect. A high light-to-electricity conversion yield (9.3%) was attained by applying these titania nanoscale materials for making an electrode of dye-sensitized solar cells. PMID:24198457

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

2008-01-01

214

Stabilizing chromophore binding on TiO2 for long-term stability of dye-sensitized solar cells using multicomponent atomic layer deposition.  

PubMed

Ambient humidity and high temperature are known to degrade dye-sensitized solar cells (DSSCs) via chromophore desorption. Recently, enhanced dye-attachment to TiO2 surfaces has been realized by coating molecularly functionalized surfaces with inorganic atomic layer deposition (ALD) coatings. Here, we apply this ALD approach to DSSCs and demonstrate that high energy conversion efficiencies can be maintained while significantly extending device lifetimes. While single component ALD layers show improved high-temperature stability, it significantly degraded up to 45% of initial DSSC performance right after ALD. We, however, find that mixed component ALD layers provide initial efficiencies within 90% of their untreated counterparts while still extending device lifetimes. Optimized ALD protection schemes maintain 80% of their initial efficiency after 500 h of thermal aging at 80 °C whereas efficiency of DSSCs with no ALD protection drop below 60% of their initial efficiencies. IR spectroscopy conducted in situ during ALD reveals that carboxylate linker groups transition from unbound or weakly-bound states, respectively, to more strongly bound bidentate structures. This strategy to improve dye-attachment by ALD while maintaining high performance is novel and promising for extending the functional lifetime for DSSCs and other related devices. PMID:24676056

Kim, Do Han; Losego, Mark D; Hanson, Kenneth; Alibabaei, Leila; Lee, Kyoungmi; Meyer, Thomas J; Parsons, Gregory N

2014-05-14

215

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

PubMed

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

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

2013-10-23

216

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

Microsoft Academic Search

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

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

2011-01-01

217

One-step preparation and assembly of aqueous colloidal CdS(x)Se(1-x) nanocrystals within mesoporous TiO2 films for quantum dot-sensitized solar cells.  

PubMed

In the field of quantum dots (QDs)-sensitized solar cells, semiconductor QDs sensitizer with a moderate band gap is required in order to sufficiently match the solar spectrum and achieve efficient charge separation. At present, changing the size of QDs is the main method used for adjusting their band gap through quantum size effect, however, the pore sizes of mesoporous TiO2 film set a limit on the allowed size of QDs. Therefore, the tuning of electronic and optical properties by changing the particle size could be limited under some circumstances. In this paper, high-quality aqueous CdS(x)Se(1-x) QDs sensitizer is successfully synthesized and effectively deposited on a mesoporous TiO2 film by a one-step hydrothermal method. In addition to size, alloy QDs provide composition as an additional dimension for tailoring their electronic properties. The alloy composition and band gap can be precisely controlled by tuning the precursor (Se/Na2S·9H2O) ratio while maintaining the similar particle size. By using such CdS(x)Se(1-x) sensitized TiO2 films as photoanodes for solar cell, a maximum power conversion efficiency of 2.23% is achieved under one sun illumination (AM 1.5 G, 100 mW cm(-2)). PMID:23659502

Song, Xiaohui; Wang, Minqiang; Deng, Jianping; Yang, Zhi; Ran, Chenxin; Zhang, Xiangyu; Yao, Xi

2013-06-12

218

Nanoporous TiO 2 solar cells sensitized with iron(II) complexes of bromopyrogallol red ligand  

Microsoft Academic Search

Complexation of bromopyrogallol ligand with di(aqua)bis(oxalato)iron(II) moiety, [Fe(II)(H2O)2(C2O4)1]2?, shows enhanced photovoltaic properties when compared with the photovoltaic cells coated by bromopyrogallol ligand only. Electrochemical and absorption spectroscopic data suggest the nature of the lowest electronic transition of iron(II) complex as a ??(bpr)?d?(Fe), metal to ligand charge transfer transition. Photovoltaic cells coated with bromopyrogallol ligand complexed with iron(II) shows higher stability

P. M. Jayaweera; S. S. Palayangoda; K. Tennakone

2001-01-01

219

An Insight into the Role of Oxygen Vacancy in Hydrogenated TiO2 Nanocrystals in the Performance of Dye-Sensitized Solar Cells.  

PubMed

Hydrogenated titanium dioxide (H-TiO2) nanocrystals were successfully prepared via annealing TiO2 in H2/N2 mixed gas flow at elevated temperatures ranging from 300 to 600 °C. Electron paramagnetic resonance (EPR) spectra were used to determine the produced oxygen vacancy in H-TiO2. Variations in temperature were studied to investigate the concentration change of oxygen vacancy in H-TiO2. The H-TiO2 nanocrystals prepared at different temperatures were employed into photoanodes sensitized by N719 dye and found to have exceptional effect on the solar-to-electric energy conversion efficiency (?). Photoanodes with H-TiO2 nanocrystals hydrogenated at 300 °C show the highest short-circuit current density (Jsc) of 18.92 mA cm(-2) and photoelectrical conversion efficiency of 7.76% under standard AM 1.5 global solar irradiation, indicating a 27 and 28% enhancement in Jsc and ?, respectively, in comparison to those with TiO2. The enhancement is attributed to high donor density, narrow band gap and positive shift of flat band energy (Vfb) of H-TiO2 that promote the driving force for electron injection. Intensity-modulated photocurrent spectroscopy (IMPS) accompanied by intensity-modulated photovoltage spectroscopy (IMVS) and other analyses were applied to shed more light on the fundamental mechanisms inside the charge transfer and transport in these systems. PMID:25621977

Su, Ting; Yang, Yulin; Na, Yong; Fan, Ruiqing; Li, Liang; Wei, Liguo; Yang, Bin; Cao, Wenwu

2015-02-18

220

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

221

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

222

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

PubMed

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

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

2005-03-01

223

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

224

Properties of Pulsed-Laser-Deposited CuI and Characteristics of Constructed Dye-Sensitized TiO2|Dye|CuI Solid-State Photovoltaic Solar Cells  

NASA Astrophysics Data System (ADS)

Transparent semiconducting copper iodide (CuI) films were deposited by pulsed laser deposition and their characteristics were investigated. In this paper, the structural and optoelectrical properties of CuI thin films and the construction of dye-sensitized TiO2|Dye|CuI solid-state photovoltaic solar cells are reported. The optical absorption of these films shows a remarkable blue shift compared to that of polycrystalline CuI, which can be explained by the formation of ultrafine CuI grains. The CuI films exhibited an optical transmittance of over 80% in wavelengths ranging from 400 to 900 nm and a minimum resistivity of approximately 2 K?\\cdotcm. The properties of pulsed-laser-deposited CuI in the power output of n-TiO2|Dye|p-CuI cells is studied. An efficient charge generation is observed through the illumination of the TiO2 layer of the fabricated n-TiO2|Dye|p-CuI cells. The cell performance has been characterized base on the current-voltage (I-V) working curve determined under AM 1.5 illumination conditions (100 mW/cm2, 25°C). The maximum short-circuit photocurrent density (Jsc) of approximately 12.2 mA/cm2 and open-circuit photovoltage (Voc) of approximately 480 mV were obtained for the TiO2|Dye|CuI solid-state photovoltaic solar cells with good reproducibility. The fill factor (FF) and power conversion efficiency (?) were about 47.8% and 2.8%, respectively.

Rusop, Mohamad; Shirata, Tetsuya; Sirimanne, Prasad M.; Soga, Tetsuo; Jimbo, Takashi

2003-08-01

225

Photovoltaic enhancement of dye-sensitized solar cell prepared from [TiO 2\\/ethyl cellulose\\/terpineol] paste employing TRITON™ X-based surfactant with carboxylic acid group in the oxyethylene chain end  

Microsoft Academic Search

This paper describes the formulation of nanocrystalline TiO2 paste for dye-sensitized solar cell (DSSC) applications employing a series of TRITON™ X-based surfactants with an octyl phenol ethoxylate (OPE) backbone and various chain ends. Five different functional group-terminated TRITON™ X (or OPE) derivatives, [OPE5-OH], [OPE5-COOH], [OPE5-NH2], [OPE5-Imidazole], and [OPE5-OPO(OH)2], were prepared from OPE of 5 oxyethylene units (n=5). The carboxylic acid-terminated

Jung-Gyu Nam; Eun-Sung Lee; Won-Cheol Jung; Young-Jun Park; Byung-Hee Sohn; Sang-Cheol Park; Joo Sung Kim; Jin-Young Bae

2009-01-01

226

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

227

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

228

Effect of solvents on the extraction of natural pigments and adsorption onto TiO2 for dye-sensitized solar cell applications.  

PubMed

Nine solvents, namely, n-hexane, ethanol, acetonitrile, chloroform, ethyl-ether, ethyl-acetate, petroleum ether, n-butyl alcohol, and methanol were used to extract natural dyes from Cordyline fruticosa, Pandannus amaryllifolius and Hylocereus polyrhizus. To improve the adsorption of dyes onto the TiO2 particles, betalain and chlorophyll dyes were mixed with methanol or ethanol and water at various ratios. The adsorption of the dyes mixed with titanium dioxide (TiO2) was also observed. The highest adsorption of the C.fruticosa dye mixed with TiO2 was achieved at ratio 3:1 of methanol: water. The highest adsorption of P.amaryllifolius dye mixed with TiO2 was observed at 2:1 of ethanol: water. H.polyrhizus dye extracted by water and mixed with TiO2 demonstrated the highest adsorption among the solvents. All extracted dye was adsorbed onto the surface of TiO2 based on Fourier Transform Infrared Spectroscopy (FTIR) analysis. The inhibition of crystallinity of TiO2 was likewise investigated by X-ray analysis. The morphological properties and composition of dyes were analyzed via SEM and EDX. PMID:25483560

Al-Alwani, Mahmoud A M; Mohamad, Abu Bakar; Kadhum, Abd Amir H; Ludin, Norasikin A

2015-03-01

229

Optical excitations of metallic nanoclusters buried in TiO2 for solar photochemistry  

E-print Network

Optical excitations of metallic nanoclusters buried in TiO2 for solar photochemistry Fei Wang State University, Baton Rouge, LA 70803-4001 ABSTRACT Ag deposited on TiO2(110) forms nanoclusters ~5 nm across and 2 nm in height, shown by STM. These nanoclusters exhibit a plasmon loss at 3.8 e

230

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

231

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

E-print Network

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

Park, Byungwoo

232

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

Microsoft Academic Search

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

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

2010-01-01

233

Eosin-Y and N3Dye sensitized solar cells (DSSCs) based on novel nanocoral TiO 2: A comparative study  

Microsoft Academic Search

Titanium oxide (TiO2) nanocorals containing nanopolyps have been synthesized by a cost effective hydrothermal route directly on fluorine doped tin oxide (FTO) coated conducting glass substrates. 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 Raman spectroscopy, room temperature photoluminescence spectroscopy and X-ray photoelectron

Sawanta S. Mali; C. A. Betty; P. N. Bhosale; P. S. Patil

234

RESEARCH ARTICLE Nanoimprinted Tio2 solgel passivating diffraction  

E-print Network

RESEARCH ARTICLE Nanoimprinted Tio2 sol­gel passivating diffraction gratings for solar cell, Australia ABSTRACT We report the fabrication and characterization of TiO2 sol­gel diffraction gratings for solar cells. Copyright © 2011 John Wiley & Sons, Ltd. KEYWORDS TiO2 sol­gel; diffraction grating; solar

235

Synthesis of low-cost, rubbery amphiphilic comb-like copolymers and their use in the templated synthesis of mesoporous TiO2 films for solid-state dye-sensitized solar cells.  

PubMed

Low-cost, rubbery amphiphilic comb-like copolymers consisting of hydrophobic poly(lauryl methacrylate) (PLMA) and hydrophilic poly(oxyethylene methacrylate) (POEM) were synthesized via one-step free radical polymerization. The synthesis of PLMA-POEM copolymers was confirmed using Fourier transform infra-red spectroscopy (FT-IR), (1)H-nuclear magnetic resonance ((1)H-NMR) and gel permeation spectroscopy (GPC). The PLMA-POEM copolymers were used as a structure-directing agent for the formation of anatase mesoporous TiO2 films. Careful adjustment of the precursor and polymer molecular weight (MW) was made to systematically vary the TiO2 structure and its effect on the performances of solid-state dye-sensitized solar cells (ssDSSCs). The use of a low MW polymer resulted in a worm-like structure with smaller pores, whereas an aggregated honeycomb-like structure with bimodal pores was obtained for the high MW system, as characterized by scanning electron microscopy (SEM), grazing incidence small-angle X-ray scattering (GI-SAXS) and N2 adsorption-desorption measurement. An efficiency of 4.2% was obtained at 100 mW cm(-2) when using 2 ?m-thick TiO2 film prepared with a high MW copolymer. The higher efficiency was due to better pore filling of the solid electrolyte and improved light scattering properties. By using a layer-by-layer method, the efficiency was further improved to 5.0% at 7 ?m thickness, which was greater than that of commercially available paste (3.9%). PMID:23575937

Kim, Dong Jun; Kim, Sang Jin; Roh, Dong Kyu; Kim, Jong Hak

2013-05-21

236

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

237

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

238

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

239

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

NASA Astrophysics Data System (ADS)

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

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

2013-11-01

240

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

241

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

PubMed

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

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

2014-07-01

242

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

243

The effect of TiO2 surface on the electron injection efficiency in PbS quantum dot solar cells: a first-principles study.  

PubMed

We present a density functional theory (DFT) study aimed at understanding the injection and recombination processes that occur at the interface between PbS QDs and TiO2 oxide nanoparticles with different morphologies. The calculated injection rates fall in the picosecond timescale in good agreement with the experiments. In addition, our simulations show that the (101) facet of TiO2 more favourably accommodates the QD, resulting in stronger electronic couplings and faster electron injections than the (001) surfaces. Despite this, the (101) slab is also more prone to faster electron recombination with the valence band of the QD, which can lead to overall lower injection efficiencies than the (001) surface. PMID:25642467

Azpiroz, Jon M; Ugalde, Jesus M; Etgar, Lioz; Infante, Ivan; De Angelis, Filippo

2015-02-10

244

A Highly Efficient Solar Cell Made from a Dye-Modified ZnO-Covered TiO2 Nanoporous Electrode  

E-print Network

. Besides TiO2,1-3 other semiconductors, such as SnO2,4 Fe2O3,5 ZrO2,6 Al2O3,7 ZnO,8 et al., have also been studied for photoelectric conversion. Among all those materials studied, whether single4-8 or composite9 difficult with the increase of photocurrent in the absence of space charge layer.11 The efficiency of dye

Huang, Yanyi

245

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

246

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

E-print Network

of Chemistry and Chemical Engineering, Xiamen University, 7 Xiamen 361005, China 8 *S Supporting Information 9 ABSTRACT: Because of their special application in photo- 10 voltaics, the growth of one-dimensional single rod is etched into a number of small nanowires. Tube-shaped 17 dye-sensitized solar cells

Wang, Zhong L.

247

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

248

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

PubMed

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. PMID:25102925

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

2014-09-01

249

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

250

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 (2.95eV) compared to undoped sample (3.13eV) and other doped samples (3.05eV) 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

251

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

PubMed

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

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

2013-10-21

252

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

253

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

254

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

PubMed Central

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

2014-01-01

255

Adsorption and solar light decomposition of acetone on anatase TiO2 and niobium doped TiO2 thin films.  

PubMed

Adsorption and solar light decomposition of acetone was studied on nanostructured anatase TiO2 and Nb-doped TiO2 films made by sol-gel methods (10 and 20 mol % NbO2.5). A detailed characterization of the film materials show that films contain only nanoparticles with the anatase modification with pentavalent Nb oxide dissolved into the anatase structure, which is interpreted as formation of substituted Nb=O clusters in the anatase lattice. The Nb-doped films displayed a slight yellow color and an enhanced the visible light absorption with a red-shift of the optical absorption edge from 394 nm for the pure TiO2 film to 411 nm for 20 mol % NbO2.5. In-situ Fourier transform infrared (FTIR) transmission spectroscopy shows that acetone adsorbs associatively with eta1-coordination to the surface cations on all films. On Nb-doped TiO2 films, the carbonyl bonding to the surface is stabilized, which is evidenced by a lowering of the nu(C=O) frequency by about 20 cm(-1) to 1672 cm(-1). Upon solar light illumination acetone is readily decomposed on TiO2, and stable surface coordinated intermediates are formed. The decomposition rate is an order of magnitude smaller on the Nb-doped films despite an enhanced visible light absorption in these materials. The quantum yield is determined to be 0.053, 0.004 and 0.002 for the pure, 10% Nb:TiO2, and 20%Nb:TiO2, respectively. Using an interplay between FTIR and DFT calculations we show that the key surface intermediates are bidentate bridged formate and carbonate, and H-bonded bicarbonate, respectively, whose concentration on the surface can be correlated with their heats of formation and bond strength to coordinatively unsaturated surface Ti and Nb atoms at the surface. The oxidation rate of these intermediates is substantially slower than the initial acetone decomposition rate, and limits the total oxidation rate at t>7 min on TiO2, while no decrease of the rate is observed on the Nb-doped films. The rate of degradation of key surface intermediates is different on pure TiO2 and Nb-doped TiO2, but cannot explain the overall lower total oxidation rate for the Nb-doped films. Instead the inferior photocatalytic activity in Nb-doped TiO2 is attributed to an enhanced electron-hole pair recombination rate due to Nb=O cluster and cation vacancy formation. PMID:16471666

Mattsson, Andreas; Leideborg, Michael; Larsson, Karin; Westin, Gunnar; Osterlund, Lars

2006-01-26

256

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.

257

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

PubMed Central

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

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

2014-01-01

258

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

259

Photocatalytic degradation of oxytetracycline using TiO 2 under natural and simulated solar radiation  

Microsoft Academic Search

The main objective of the present study was to assess the photocatalytic degradation over TiO2 of an aqueous solution containing 20mgL?1 of the antibiotic Oxytetracycline (OTC) using simulated solar radiation, seconded by a solar radiation experiment carried out in a pilot plant equipped with Compound Parabolic Collectors (CPCs) under the optimal conditions found in preliminary lab-scale experiments. These comprehended a

João H. O. S. Pereira; Vítor J. P. Vilar; Maria T. Borges; Oscar González; Santiago Esplugas; Rui A. R. Boaventura

2011-01-01

260

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

261

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

PubMed

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

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

2010-01-01

262

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

263

A facile method to prepare SnO2 nanotubes for use in efficient SnO2-TiO2 core-shell dye-sensitized solar cells.  

PubMed

A high-efficiency photoelectrode for dye-sensitized solar cells (DSSCs) should combine the advantageous features of fast electron transport, slow interfacial electron recombination and large specific surface area. However, these three requirements usually cannot be achieved simultaneously in the present state-of-the-art research. Here we report a simple procedure to combine the three conflicting requirements by using porous SnO(2) nanotube-TiO(2) (SnO(2) NT-TiO(2)) core-shell structured photoanodes for DSSCs. The SnO(2) nanotubes are prepared by electrospinning of polyvinyl pyrrolidone (PVP)/tin dichloride dihydrate (SnCl(2)·2H(2)O) solution followed by direct sintering of the as-spun nanofibers. A possible evolution mechanism is proposed. The power conversion efficiency (PCE) value of the SnO(2) NT-TiO(2) core-shell structured DSSCs (?5.11%) is above five times higher than that of SnO(2) nanotube (SnO(2) NT) DSSCs (?0.99%). This PCE value is also higher than that of TiO(2) nanoparticles (P25) DSSCs (?4.82%), even though the amount of dye molecules adsorbed to the SnO(2) NT-TiO(2) photoanode is less than half of that in the P25 film. This simple procedure provides a new approach to achieve the three conflicting requirements simultaneously, which has been demonstrated as a promising strategy to obtain high-efficiency DSSCs. PMID:22572999

Gao, Caitian; Li, Xiaodong; Lu, Bingan; Chen, Lulu; Wang, Youqing; Teng, Feng; Wang, Jiangtao; Zhang, Zhenxing; Pan, Xiaojun; Xie, Erqing

2012-06-01

264

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

PubMed

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

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

2013-12-15

265

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

266

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

267

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.

2015-01-01

268

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

269

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

PubMed

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

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

2013-09-01

270

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

NASA Astrophysics Data System (ADS)

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

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

2014-06-01

271

Nanometer-thin TiO2 enhances skeletal muscle cell phenotype and behavior  

PubMed Central

Background The independent role of the surface chemistry of titanium in determining its biological properties is yet to be determined. Although titanium implants are often in contact with muscle tissue, the interaction of muscle cells with titanium is largely unknown. This study tested the hypotheses that the surface chemistry of clinically established microroughened titanium surfaces could be controllably varied by coating with a minimally thin layer of TiO2 (ideally pico-to-nanometer in thickness) without altering the existing topographical and roughness features, and that the change in superficial chemistry of titanium is effective in improving the biological properties of titanium. Methods and results Acid-etched microroughened titanium surfaces were coated with TiO2 using slow-rate sputter deposition of molten TiO2 nanoparticles. A TiO2 coating of 300 pm to 6.3 nm increased the surface oxygen on the titanium substrates in a controllable manner, but did not alter the existing microscale architecture and roughness of the substrates. Cells derived from rat skeletal muscles showed increased attachment, spread, adhesion strength, proliferation, gene expression, and collagen production at the initial and early stage of culture on 6.3 nm thick TiO2-coated microroughened titanium surfaces compared with uncoated titanium surfaces. Conclusion Using an exemplary slow-rate sputter deposition technique of molten TiO2 nanoparticles, this study demonstrated that titanium substrates, even with microscale roughness, can be sufficiently chemically modified to enhance their biological properties without altering the existing microscale morphology. The controllable and exclusive chemical modification technique presented in this study may open a new avenue for surface modifications of titanium-based biomaterials for better cell and tissue affinity and reaction. PMID:22114483

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

2011-01-01

272

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

273

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

PubMed Central

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

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

2012-01-01

274

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

275

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

276

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

277

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

Microsoft Academic Search

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

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

2010-01-01

278

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

PubMed Central

The response of primary human endothelial (ECs) and vascular smooth muscle cells (VSMCs) to TiO2 nanotube arrays is studied through gene expression analysis. Microarrays revealed that nanotubes enhanced EC proliferation and motility, decreased VSMC proliferation, and decreased expression of molecules involved in inflammation and coagulation in both cell types. Networks generated from significantly affected genes suggest that cells may be sensing nanotopographical cues via pathways previously implicated in sensing shear stress. PMID:20030358

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

2010-01-01

279

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

2015-02-10

280

Effect of anatase TiO2 nanoparticles on the growth of RSC-364 rat synovial cell.  

PubMed

Nanoscale materials (such as TiO2, hydroxyapatite nanoparticles) have gained much concern in the coating of implants for cell adhesion and growth to improve the osteoconductivity. However, due to attrition and corrosion, the wear particles would be generated from the joint in living organism, and influence the physiological function of synovial membranes in joint cavity. In this study, the potential cytotoxicity of anatase TiO2 nanoparticles (TiO2 NPs) on rat synovial cell line 364 (RSC-364) was investigated. After treatment with different concentrations of TiO2 NPs (0, 3, 30, 300 microg/ml), the viability of RSC-364 cells were decreased in a dose-dependent manner. TiO2 NPs exposure could disrupt the integrity of cell plasma membrane, leading to the increased leakage of lactate dehydrogenase (LDH) into the culture medium. TiO2 NPs were uptaken by RSC-364 cells. The ultrastructure of RSC-364 cells was changed such as nuclear shrinkage and mitochondrial swelling. The reactive oxygen species (ROS) was over-produced especially in the cells exposed to 30 and 300 microg/ml TiO2 NPs. The activities of endogeneous antioxidant enzymes, superoxide dismutase (SOD) and catalase (CAT), were significantly decreased. The increased lipid peroxidation product (malondialdehyde, MDA) suggests the oxidative damage in cells. The flow cytometry detected that the cell cycle was blocked in G0/G1 phase, inhibiting the cell proliferation. These preliminary results indicate the oxidative stress injury and cytotoxicity of anatase TiO2 NPs on rat synovial cells. The reasonable and safe application of nanomaterials in artificial implants needs further study. PMID:23862421

Wang, Jiangxue; Ma, Jiawei; Dong, Linmeng; Hou, Ying; Jia, Xiaoling; Niu, Xufeng; Fan, Yubo

2013-06-01

281

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

282

UVB irradiation enhances TiO2 nanoparticle-induced disruption of calcium homeostasis in human lens epithelial cells.  

PubMed

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

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

2014-01-01

283

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

284

Aperiodic TiO2 nanotube photonic crystal: full-visible-spectrum solar light harvesting in photovoltaic devices.  

PubMed

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

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

2014-01-01

285

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

PubMed

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

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

2012-03-01

286

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

287

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

288

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

Microsoft Academic Search

We have studied the effects of exposure of human dermal fibroblasts to rutile and anatase TiO2 nanoparticles. We found that these particles can impair cell functions, with the latter being more potent at producing damage. We showed that the exposure to nanoparticles decreases cell area, cell proliferation, mobility, and ability to contract collagen. Individual particles are shown to penetrate easily

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

2009-01-01

289

Porphyrin-sensitized nanoparticulate TiO2 as the photoanode of a hybrid photoelectrochemical biofuel cell.  

PubMed

Porphyrin-sensitized nanoparticulate TiO(2) on conducting glass has been investigated as a photoanode material for a new cell that converts light energy into electricity. The cell is a hybrid of a dye-sensitized nanoparticulate semiconductor photoelectrochemical solar cell, and a biofuel cell that oxidizes glucose. Porphyrin molecules excited by light inject electrons into the photoanode, from where they enter the external circuit. The resulting porphyrin radical cations are reduced by NADH in aqueous buffer, ultimately regenerating the photoanode and producing NAD(+). Glucose dehydrogenase oxidizes glucose, and in the process recycles NAD(+) back to NADH. The photoanode is coupled with a suitable cathode to make a functioning cell (Hg/Hg(2)SO(4) was employed for evaluation purposes). The cell produces 1.1 V at open circuit and has a fill factor of 0.61. These values are both significantly higher than those for a previously reported cell of a similar type based on an SnO(2) electrode. PMID:15350115

Brune, Alicia; Jeong, Goojin; Liddell, Paul A; Sotomura, Tadashi; Moore, Thomas A; Moore, Ana L; Gust, Devens

2004-09-14

290

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

PubMed

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

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

2013-12-11

291

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

Microsoft Academic Search

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

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

2011-01-01

292

TiO2 thin film deposition by chemical methods  

NASA Astrophysics Data System (ADS)

Mesoporous nanocrystalline TiO2 dye sensitized solar cells was obtained by the sol-gel process in an aqueous solution using the titanium diethanolamine complex as the precursor and the spin coating technique to obtain TiO2 films on ITO (Indium tin oxide) glass substrates. TG - DTA, BET, FT-IR, UV - VIS, SEM, Raman spectroscopy, X-ray diffraction techniques, have been used to investigate the chemical and physical changes during the sol - gel process and the characteristics of the TiO2 powder precursor.

Suciu, R.-C.; Ro?u, M. C.-; Marian, I.; Silipa?, T. D.; Varodi, C.; Popa, A.; Mihe?, M.; Indrea, E.

2012-02-01

293

Highly active nanocrystalline TiO(2) photoelectrodes.  

PubMed

A simple method for the fabrication of highly photoactive nanocrystalline two-layer TiO(2) electrodes for solar cell applications is presented. Diluted titanium acetylacetonate has been used as a precursor for covering SnO(2):F (FTO) films with dense packed TiO(2) nanocrystallites. The nanoporous thick TiO(2) film follows the dense packed thin TiO(2) film as a second layer. For the latter, amorphous TiO(2) nanoparticles have been successfully synthesized by a sol-gel technique in an acidic environment with pH<1 and hydrothermal growth at a temperature of 200?°C. The acidic nanoparticle gel was neutralized by basic ammonia and a TiO(2) gel of pH 5 was obtained; this pH value is higher than the recently reported value of 3.1 (Park et al 2005 Adv. Mater. 17 2349-53). Highly interconnected, nanoporous, transparent and active TiO(2) films have been fabricated from the pH 5 gel. SEM, AFM and XRD analyses have been carried out for investigation of the crystal structure and the size of nanoparticles as well as the surface morphology of the films. Investigation of the photocurrent-voltage characteristics has shown improvement in cell performance along with the modification of the surface morphology, depending on pH of the TiO(2) gel. Increasing the pH of the gel from 2.1 to 5 enhanced the overall conversion efficiency of the dye-sensitized solar cells by approximately 30%. An energy conversion efficiency of 8.83% has been achieved for the cell (AM1.5, 100  mWcm(-2) simulated sunlight) compared to 6.61% efficiency in the absence of ammonia in the TiO(2) gel. PMID:21730548

Paronyan, Tereza M; Kechiantz, A M; Lin, M C

2008-03-19

294

A Facile Method for Synthesizing TiO2 Sea-Urchin-Like Structures and Their Applications in Solar Energy Harvesting  

NASA Astrophysics Data System (ADS)

We present a new method to prepare TiO2 sea-urchin-like structures, which involves the initial formation of tubular nanostructures and subsequent self-assembly of the nanotubes into micrometer-scale sea-urchin-like structures. We also investigate the important role of alkali aqueous conditions in the preparation of TiO2 sea-urchin-like structures. This facile and cost-effective approach provides a new route for the preparation of self-assembled TiO2 structures. In addition, the performance of the as-synthesized TiO2 sea-urchin-like structures as the active layer of an efficient solar energy harvester is also studied and discussed.

Wang, Wen-Hui; Wang, Wen-Zhong; Xu, Hong-Xing

2011-07-01

295

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

296

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

297

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

PubMed

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

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

2014-01-01

298

TiO2 nanoparticles induce insulin resistance in liver-derived cells both directly and via macrophage activation.  

PubMed

Upon exposure, TiO(2) nanoparticles (NPs) have been recovered in internal organs such as the liver, and are proposed to cause cellular/organ dysfunction, particularly in the liver and lungs. We hypothesized that despite being considered "inert" as bulk material, TiO(2) NPs may impair insulin responses in liver-derived cells, either indirectly by inflammatory activation of macrophages, and/or by directly interfering with insulin signaling. Using qRT-PCR and conditioned medium (CM) approaches, we show that exposure to TiO(2) NPs activates macrophages' expression of TNF-?, IL-6, IL-8, IL-1? and IL-1? and the resulting CM induces insulin resistance in Fao cells. Furthermore, direct exposure of Fao cells to TiO(2) results in activation of the stress kinases JNK and p38MAP kinase, and in induction of insulin resistance at the signaling and metabolic levels. Collectively, our findings provide a proof-of-concept for the ability of man-made NPs to induce insulin resistance in liver-derived cells, an endocrine abnormality underlying some of the most common human diseases. PMID:22007682

Gurevitch, Diana; Shuster-Meiseles, Timor; Nov, Ori; Zick, Yehiel; Rudich, Assaf; Rudich, Yinon

2012-12-01

299

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

PubMed

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

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

2013-07-01

300

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

PubMed

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

Ghosh, Manosij; Chakraborty, Anirban; Mukherjee, Anita

2013-10-01

301

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

NASA Astrophysics Data System (ADS)

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

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

2014-01-01

302

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

NASA Astrophysics Data System (ADS)

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

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

2012-12-01

303

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

PubMed

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

Huang, Tingyu; Jie, Guifen

2013-11-01

304

Surface Treatment for Effective Dye Adsorption on Nanocrystalline TiO2  

NASA Astrophysics Data System (ADS)

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

Yanagida, Masatoshi; Han, Chen; Han, Liyuan

2012-10-01

305

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

PubMed

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

Hamzeh, Mahsa; Sunahara, Geoffrey I

2013-03-01

306

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

PubMed

To endow titanium (Ti) with antibacterial properties, different concentrations of zinc oxide (ZnO) nanoparticles were decorated on anodized titanium dioxide (TiO2) nanotubes by a simple hydrothermal treatment method. The particle sizes of ZnO, which were evenly distributed and tightly adherent to the walls of the Ti nanotubes, ranged from 20-50 nm. Results from this study showed that Zn was released from the TiO2 nanotubes in a constant, slow, and biologically inspired manner. Importantly, the results showed that the ZnO decorated TiO2 nanotubular samples inhibited Streptococcus mutants and Porphyromonas gingivalis growth compared to control unmodified Ti samples. Specifically, S. mutants and P. gingivalis growth were both reduced 45-85% on the ZnO decorated Ti samples compared to Ti controls after 7 days of culture. When examining the mechanism of action, it has been further found for the first time that the ZnO decorated Ti samples inhibited the expression of Streptococcus mutans bacterial adhesion genes. Lastly, the results showed that the same samples which decreased bacterial growth the most (0.015 M precursor Zn(NO3)2 samples) did not inhibit mesenchymal stem cell growth compared to Ti controls for up to 7 days. In summary, results from this study showed that compared to plain TiO2 nanotubes, TiO2 decorated with 0.015 M ZnO provided unprecedented antibacterial properties while maintaining the stem cell proliferation capacity necessary for enhancing the use of Ti in numerous medical applications, particularly in dentistry. PMID:24971593

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

2014-08-01

307

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

308

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

309

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

310

Cytotoxicity of TiO2 nanoparticles to mussel hemocytes and gill cells in vitro: Influence of synthesis method, crystalline structure, size and additive.  

PubMed

Abstract Increasing the production and applications of TiO2 nanoparticles (NPs) has led to grow concerns about the consequences for the environment. In this study, we investigated the effects of a set of TiO2 NPs on the viability of mussel hemocytes and gill cells using neutral red and thiazolyl tetrazolium bromide assays. For this, we compared the cytotoxicity of TiO2 NPs (0.1-100?mg Ti/L) produced by different techniques: rutile NPs (60?nm) produced by milling and containing disodium laureth sulfosuccinate (DSLS), rutile NPs (10, 40 and 60?nm) produced by wet chemistry and anatase/rutile NPs (?100?nm) produced by plasma synthesis. The commercially available P25 anatase/rutile NPs (10-20?nm) were also tested. Exposures were performed in parallel with their respective bulk forms and the cytotoxicity of the additive DSLS was also tested. Z potential values in distilled water indicated different stabilities depending on the NP type and all NPs tested formed agglomerates/aggregates in cell culture media. In general, TiO2 NPs showed a relatively low and dose-dependent toxicity for both cell models with the two assays tested. NPs produced by milling showed the highest effects, probably due to the toxicity of DSLS. Size-dependent toxicity was found for NPs produced by wet chemistry (10?nm?>?40?nm and 60?nm). All TiO2 NPs tested were more toxic than bulk forms excepting for plasma produced ones, which were the least toxic TiO2 tested. The mixture bulk anatase/rutile TiO2 was more toxic than bulk rutile TiO2. In conclusion, the toxicity of TiO2 NPs varied with the mode of synthesis, crystalline structure and size of NPs and can also be influenced by the presence of additives in the suspensions. PMID:25188678

Katsumiti, Alberto; Berhanu, Deborah; Howard, Kieren T; Arostegui, Inmaculada; Oron, Miriam; Reip, Paul; Valsami-Jones, Eugenia; Cajaraville, Miren P

2014-09-01

311

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

312

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

PubMed Central

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

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

2014-01-01

313

Solar-light photoamperometric and photocatalytic properties of quasi-transparent TiO2 nanoporous thin films.  

PubMed

Transparent photocatalytic surfaces are of ever increasing importance for many applications on self-cleaning windows and tiles in everyday applications. Here, we report the formation and photocatalytic testing of a quasi-transparent thin and nanoporous titania films deposited on glass plates. Sputtered Ti thin films were anodized in fluoride-ion-containing neutral electrolytes to form optically semitransparent nanoporous films, which transformed to be completely transparent after thermal annealing. The nanoporous films were studied at different stages, such as before and after anodization, as well as after thermal annealing using scanning electron microscopy (SEM), X-ray diffraction (XRD), and UV-vis and Raman spectroscopy. It was observed that anodization at 20 V of high-temperature deposited titanium films resulted in regular nanopore films with pore diameters of 30 nm. Structural investigations on the transparent nanopore arrays reveal the presence of anatase phase TiO(2) even after annealing at 500 °C, which was confirmed by XRD and Raman spectroscopy measurements. The solar-light induced photocatalytic decomposition of stearic acid and photoconductivity characteristics of these nanoporous thin films are also presented. PMID:20973502

Ji, Yajun; Lin, Keng-Chu; Zheng, Hegen; Liu, Chung-Chiun; Dudik, Laurie; Zhu, Junjie; Burda, Clemens

2010-11-01

314

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

315

Crystal structure mediates mode of cell death in TiO 2 nanotoxicity  

Microsoft Academic Search

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

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

2009-01-01

316

Diatom-templated TiO2 with enhanced photocatalytic activity: biomimetics of photonic crystals  

NASA Astrophysics Data System (ADS)

The siliceous frustules with sophisticated optical structure endow diatoms with superior solar light-harvesting abilities for effective photosynthesis. The preserved frustules of diatom ( Cocconeis placentula) cells, as biophotonic crystals, were thus employed as both hard templates and silicon resources to synthesize TiO2 photocatalyst. Characterizations by a combination of physicochemical techniques proved that the bio-inspired sample is TiO2-coated SiO2 with biogenic C self-doped in. It was found that the synthesized composites exhibited similar morphologies to the original diatom templates. In comparison with commercial Degussa P25 TiO2, the C-doped TiO2/SiO2 catalyst exhibited more light absorption in the visible region and higher photocatalytic efficiency for photodegradation of rhodamine B under visible light due to the biomorphic hierarchical structures, TiO2 coating and C-doping.

He, Jiao; Chen, Daomei; Li, Yongli; Shao, Junlong; Xie, Jiao; Sun, Yuejuan; Yan, Zhiying; Wang, Jiaqiang

2013-11-01

317

Enhanced DSSC performance with high surface area thin anatase TiO 2 nanoleaves  

Microsoft Academic Search

Thin anatase TiO2 nanoleaves (NLs) with high surface area (?93m2\\/g) are synthesized by hydrothermal route and dye-sensitized solar cells (DSSC) made using such NLs are compared with those made with hydro-thermally synthesized TiO2 nanoparticles and the Degussa P25 powder. The NLs-based DSSCs show increment of 16% and 24% in the total conversion efficiency over the cells made with NPs and

Vivek Dhas; Subas Muduli; Shruti Agarkar; Abhimanyu Rana; Beatrice Hannoyer; Rahul Banerjee; Satishchandra Ogale

2011-01-01

318

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

319

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

320

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

321

Electrospinning processed nanofibrous TiO(2) membranes for photovoltaic applications.  

PubMed

We have recently fabricated dye-sensitized solar cells (DSSCs) comprising nanofibrous TiO(2) membranes as electrode materials. A thin TiO(2) film was pre-deposited on fluorine doped tin oxide (FTO) coated conducting glass substrate by immersion in TiF(4) aqueous solution to reduce the electron back-transfer from FTO to the electrolyte. The composite polyvinyl acetate (PVac)/titania nanofibrous membranes can be deposited on the pre-deposited thin TiO(2) film coated FTO by electrospinning of a mixture of PVac and titanium isopropoxide in N,N-dimethylformamide (DMF). The nanofibrous TiO(2) membranes were obtained by calcining the electrospun composite nanofibres of PVac/titania as the precursor. Spectral sensitization of the nanofibrous TiO(2) membranes was carried out with a ruthenium (II) complex, cis-dithiocyanate-N,N(')-bis(2,2(')-bipyridyl-4,4(')-dicarboxylic acid) ruthenium (II) dihydrate. The results indicated that the photocurrent and conversion efficiency of electrodes can be increased with the addition of the pre-deposited TiO(2) film and the adhesion treatment using DMF. Additionally, the dye loading, photocurrent, and efficiency of the electrodes were gradually increased by increasing the average thickness of the nanofibrous TiO(2) membranes. The efficiency of the fibrous TiO(2) photoelectrode with the average membrane thickness of 3.9 µm has a maximum value of 4.14%. PMID:21727376

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

2006-02-28

322

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.

323

High-performance method for specific effect on nucleic acids in cells using TiO2~DNA nanocomposites  

NASA Astrophysics Data System (ADS)

Nanoparticles are used to solve the current drug delivery problem. We present a high-performance method for efficient and selective action on nucleic acid target in cells using unique TiO2.PL-DNA nanocomposites (polylysine-containing DNA fragments noncovalently immobilized onto TiO2 nanoparticles capable of transferring DNA). These nanocomposites were used for inhibition of human influenza A (H3N2) virus replication in infected MDCK cells. They showed a low toxicity (TC50 ~ 1800 ?g/ml) and a high antiviral activity (>99.9% inhibition of the virus replication). The specificity factor (antisense effect) appeared to depend on the delivery system of DNA fragments. This factor for nanocomposites is ten-times higher than for DNA in the presence of lipofectamine. IC50 for nanocomposites was estimated to be 1.5 ?g/ml (30 nM for DNA), so its selectivity index was calculated as ~1200. Thus, the proposed nanocomposites are prospective for therapeutic application.

Levina, Asya S.; Repkova, Marina N.; Ismagilov, Zinfer R.; Shikina, Nadezhda V.; Malygin, Ernst G.; Mazurkova, Natalia A.; Zinov'ev, Victor V.; Evdokimov, Alexei A.; Baiborodin, Sergei I.; Zarytova, Valentina F.

2012-10-01

324

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

PubMed

Cobalt-based materials are widely used for coronary stents, as well as bone and joint implants. However, their use is associated with high corrosion incidence. Titanium alloys, by contrast, are more biocompatible owing to the formation of a relatively inactive titanium oxide (TiO2) layer on their surface. This study was aimed at improving Co28Cr6Mo alloy cytocompatibility via sol-gel TiO2 coating to reduce metal corrosion and metal ion release. Owing to their role in inflammation and tissue remodelling around an implant, endothelial cells present a suitable in vitro model for testing the biological response to metallic materials. Primary human endothelial cells seeded on Co28Cr6Mo showed a stress phenotype with numerous F-actin fibres absent on TiO2-coated material. To investigate this effect at the gene expression level, cDNA microarray analysis of in total 1301 genes was performed. Compared with control cells, 247 genes were expressed differentially in the cells grown on Co28Cr6Mo, among them genes involved in proliferation, oxidative stress response and inflammation. TiO2 coating reduced the effects of Co28Cr6Mo on gene expression in endothelial cells, with only 34 genes being differentially expressed. Quantitative real-time polymerase chain reaction and protein analysis confirmed microarray data for selected genes. The effect of TiO2 coating can be, in part, attributed to the reduced release of Co(2+), because addition of CoCl2 resulted in similar cellular responses. TiO2 coating of cobalt-based materials, therefore, could be used in the production of cobalt-based devices for cardiovascular and skeletal applications to reduce the adverse effects of metal corrosion products and to improve the response of endothelial and other cell types. PMID:23825117

Tsaryk, R; Peters, K; Unger, R E; Feldmann, M; Hoffmann, B; Heidenau, F; Kirkpatrick, C J

2013-09-01

325

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

PubMed Central

Cobalt-based materials are widely used for coronary stents, as well as bone and joint implants. However, their use is associated with high corrosion incidence. Titanium alloys, by contrast, are more biocompatible owing to the formation of a relatively inactive titanium oxide (TiO2) layer on their surface. This study was aimed at improving Co28Cr6Mo alloy cytocompatibility via sol–gel TiO2 coating to reduce metal corrosion and metal ion release. Owing to their role in inflammation and tissue remodelling around an implant, endothelial cells present a suitable in vitro model for testing the biological response to metallic materials. Primary human endothelial cells seeded on Co28Cr6Mo showed a stress phenotype with numerous F-actin fibres absent on TiO2-coated material. To investigate this effect at the gene expression level, cDNA microarray analysis of in total 1301 genes was performed. Compared with control cells, 247 genes were expressed differentially in the cells grown on Co28Cr6Mo, among them genes involved in proliferation, oxidative stress response and inflammation. TiO2 coating reduced the effects of Co28Cr6Mo on gene expression in endothelial cells, with only 34 genes being differentially expressed. Quantitative real-time polymerase chain reaction and protein analysis confirmed microarray data for selected genes. The effect of TiO2 coating can be, in part, attributed to the reduced release of Co2+, because addition of CoCl2 resulted in similar cellular responses. TiO2 coating of cobalt-based materials, therefore, could be used in the production of cobalt-based devices for cardiovascular and skeletal applications to reduce the adverse effects of metal corrosion products and to improve the response of endothelial and other cell types. PMID:23825117

Tsaryk, R.; Peters, K.; Unger, R. E.; Feldmann, M.; Hoffmann, B.; Heidenau, F.; Kirkpatrick, C. J.

2013-01-01

326

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 ...

327

A novel TiO 2-assisted solar photocatalytic batch-process disinfection reactor for the treatment of biological and chemical contaminants in domestic drinking water in developing countries  

Microsoft Academic Search

The technical feasibility and performance of photocatalytic TiO2 coatings in batch-process solar disinfection (SODIS) reactors to improve potability of drinking water in developing countries have been studied. Borosilicate glass and PET plastic SODIS reactors fitted with flexible plastic inserts coated with TiO2 powder were shown to be 20% and 25% more effective, respectively, than standard SODIS reactors for the inactivation

E. F. Duffy; F. Al Touati; S. C. Kehoe; O. A. McLoughlin; L. W. Gill; W. Gernjak; I. Oller; M. I. Maldonado; S. Malato; John F Cassidy; R. H. Reed; K. G. McGuigan

2004-01-01

328

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

329

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

330

Dual effects and mechanism of TiO2 nanotube arrays in reducing bacterial colonization and enhancing C3H10T1/2 cell adhesion  

PubMed Central

Competition occurs between the osteoblasts in regional microenvironments and pathogens introduced during surgery, on the surface of bone implants, such as joint prostheses. The aim of this study was to modulate bacterial and osteoblast adhesion on implant surfaces by using a nanotube array. Titanium oxide (TiO2) nanotube arrays, 30 nm or 80 nm in diameter, were prepared by a two-step anodization on titanium substrates. Mechanically polished and acid-etched titanium samples were also prepared to serve as control groups. The standard strains of Staphylococcus epidermidis (S. epidermidis, American Type Culture Collection [ATCC]35984) and mouse C3H10T1/2 cell lines with osteogenic potential were used to evaluate the different responses to the nanotube arrays, in bacteria and eukaryotic cells. We found that the initial adhesion and colonization of S. epidermidis on the surface of the TiO2 nanotube arrays were significantly reduced and that the adhesion of C3H10T1/2 cells on the surface of the TiO2 nanotube arrays was significantly enhanced when compared with the control samples. Based on a surface analysis of all four groups, we observed increased surface roughness, decreased water contact angles, and an enhanced concentration of oxygen and fluorine atoms on the TiO2 nanotube surface. We conclude that the TiO2 nanotube surface can reduce bacterial colonization and enhance C3H10T1/2 cell adhesion; multiple physical and chemical properties of the TiO2 nanotube surface may contribute to these dual effects. PMID:23983463

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

2013-01-01

331

Application of a Schottky barrier to dye-sensitized solar cells (DSSCs) with multilayer thin films of photoelectrodes  

Microsoft Academic Search

This study combines Au nanoparticles with TiO2 nanoparticles to form a Schottky barrier, and applies it to the photoelectrode thin film of dye-sensitized solar cells (DSSCs). First, commercial TiO2 powder (Degussa P25) is put in the alkaline solution to prepare for TiO nanotubes (Tnt) by using hydrothermal treatment. Tnt are sintered at 550°C to obtain Tnt-C550 particles. In addition, TiO2

Ho Chang; Kun-Ching Cho; Chin-Guo Kuo; Mu-Jung Kao; Kuohsiu-David Huang; Kung-Hui Chu; Xiu-Ping Lin

2011-01-01

332

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

NASA Astrophysics Data System (ADS)

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

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

2011-04-01

333

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

NASA Astrophysics Data System (ADS)

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

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

2009-03-01

334

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

335

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

336

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

337

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

338

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

339

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

340

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

NASA Astrophysics Data System (ADS)

The aim of the present study is to investigate the role of the physico-chemical properties of ZnO and TiO2 NPs in the potential cytotoxicity, genotoxicity and oxidative DNA damage induction on Caco-2 cell line. As negative control, fine TiO2 particles were used. The characterization of particles was carried out by electron microscopy (SEM, TEM) using a Soft Imaging System. To evaluate the effects of ZnO and TiO2 NPs induced on Caco-2 viability, Neutral Red assay was performed after treatment with different particle concentrations. Our results showed a significant dose and time dependent effect after treatment with ZnO NPs. On the contrary, no effect was observed on Caco-2 cells exposed to TiO2 particles either in micro-and in nano-size. The role of surface in the cytotoxicity induced on Caco-2 was also considered. The levels of DNA 8-oxodG, as the main marker of oxidative DNA damage, were measured by high-performance liquid chromatography with electrochemical detection (HPLC/EC). A significant increase in the 8-oxodG levels was observed after 6 h exposure for both NPs. The estimation of the potential genotoxicity of the two NPs is ongoing by the cytokinesis-block micronucleus assay. Our preliminary results showed that a slight micronucleus increase in binucleated cells was detected in the dose range applied only for ZnO.

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

2011-07-01

341

A novel 3D structure composed of strings of hierarchical TiO2 spheres formed on TiO2 nanobelts with high photocatalytic properties  

NASA Astrophysics Data System (ADS)

A novel hierarchical titanium dioxide (TiO2) composite nanostructure with strings of anatase TiO2 hierarchical micro-spheres and rutile nanobelts framework (TiO2 HSN) is successfully synthesized via a one-step hydrothermal method. Particularly, the strings of hierarchical spheres are assembled by very thin TiO2 nanosheets, which are composed of highly crystallized anatase nanocrystals. Meanwhile, the HSN has a large surface area of 191 m2/g, which is about 3 times larger than Degussa P25. More importantly, the photocatalytic activity of HSN and P25 were evaluated by the photocatalytic oxidation decomposition of methyl orange (MO) under UV light illumination, and the TiO2 HSN shows enhanced photocatalytic activity compared with Degussa P25, as result of its continuous hierarchical structures, special conductive channel and large specific surface area. With these features, the hierarchical TiO2 may have more potential applications in the fields of dye-sensitized solar cells and lithium ion batteries.

Jiang, Yongjian; Li, Meicheng; Song, Dandan; Li, Xiaodan; Yu, Yue

2014-03-01

342

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

343

Recent progress in design, synthesis, and applications of one-dimensional TiO2 nanostructured surface heterostructures: a review.  

PubMed

One-dimensional TiO2 nanostructured surface heterostructures (1D TiO2NSHs) have been comprehensively studied during the past two decades because of the possible practical applications in various fields, including photocatalysis, dye-sensitized solar cells, sensors, lithium batteries, biomedicine, catalysis, and supercapacitors. Combining extensive advancements in materials science and nanotechnology, a 1D TiO2NSH material with well-controlled size, morphology, and composition has been designed and synthesized. More importantly, its superior properties, including a high aspect ratio structure, chemical stability, large specific surface area, excellent electronic or ionic charge transfer, and a specific interface effect, have attracted a great deal of interest in improving current performance and exploring new applications. In this tutorial review, we introduce the characteristics of 1D TiO2 nanostructures, the design principles for the fabrication of 1D TiO2NSHs, and we also summarize the recent progress in developing synthesis methods and applications of 1D TiO2NSHs in different fields. The relationship between the secondary phase and the 1D TiO2 nanostructure and between the performance in applications and the excellent physical properties of 1D TiO2NSHs are also discussed. PMID:25014328

Tian, Jian; Zhao, Zhenhuan; Kumar, Anil; Boughton, Robert I; Liu, Hong

2014-10-21

344

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

345

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

346

Anatase TiO2 nanorod-decoration for highly efficient photoenergy conversion  

NASA Astrophysics Data System (ADS)

In recent studies of inorganic materials for energy applications, surface modification processes have been shown to be among the most effective methods to enhance the performance of devices. Here, we demonstrate a facile nano-decoration method which is generally applicable to anatase TiO2 nanostructures, as well as a nano-decorated hierarchical TiO2 nanostructure which improves the energy conversion efficiency of a dye-sensitized solar cell (DSSC). Using a facile sol-gel method, 0-D, 1-D, and 2-D type anatase TiO2 nanostructures were decorated with 200 nm long anatase TiO2 nanorods to create various hierarchical nanostructures. A structural analysis reveals that the branched nanorod has a highly crystalline anatase phase with anisotropic growth in the [001] longitudinal direction. When one of the hierarchical structures, a chestnut bur-like nanostructure, was employed in a dye-sensitized solar cell as a scattering layer, offering increased dye-loading properties, preserving a sufficient level of light-scattering ability and preserving superior charge transport and recombination properties as well, the energy conversion efficiency of the cell improved by 19% (from 7.16% to 9.09%) compared to a cell with a 0-D TiO2 sphere as a scattering layer. This generally applicable anatase nanorod-decorating method offers potential applications in various energy-conversion applications, especially in DSSCs, quantum-dot solar cells, photoelectrochemical water-splitting devices, photocatalysis, and lithium ion batteries.In recent studies of inorganic materials for energy applications, surface modification processes have been shown to be among the most effective methods to enhance the performance of devices. Here, we demonstrate a facile nano-decoration method which is generally applicable to anatase TiO2 nanostructures, as well as a nano-decorated hierarchical TiO2 nanostructure which improves the energy conversion efficiency of a dye-sensitized solar cell (DSSC). Using a facile sol-gel method, 0-D, 1-D, and 2-D type anatase TiO2 nanostructures were decorated with 200 nm long anatase TiO2 nanorods to create various hierarchical nanostructures. A structural analysis reveals that the branched nanorod has a highly crystalline anatase phase with anisotropic growth in the [001] longitudinal direction. When one of the hierarchical structures, a chestnut bur-like nanostructure, was employed in a dye-sensitized solar cell as a scattering layer, offering increased dye-loading properties, preserving a sufficient level of light-scattering ability and preserving superior charge transport and recombination properties as well, the energy conversion efficiency of the cell improved by 19% (from 7.16% to 9.09%) compared to a cell with a 0-D TiO2 sphere as a scattering layer. This generally applicable anatase nanorod-decorating method offers potential applications in various energy-conversion applications, especially in DSSCs, quantum-dot solar cells, photoelectrochemical water-splitting devices, photocatalysis, and lithium ion batteries. Electronic supplementary information (ESI) available: XRD of three types of TiO2 hosts, TEM images of nanorod-decorated TiO2 hierarchical nanostructures and host 0S-TiO2, reflectance of the free-standing TiO2 nanorod, SEM images of photoelectrodes employing various scattering layers with tmax, the amount of adsorbed dye molecules per surface volume on 0S and BS monolayer films, J-V curves of the DSSCs employing each active layer with tmax thickness, the transport time constants and recombination time constants versus various scattering layer thicknesses at constant Jsc (Jsc = 0.5 mA cm-2) and the photovoltaic parameters of each DSSC employing each tmax of various scattering layers. See DOI: 10.1039/c3nr03439a

Kim, Dong Hoe; Seong, Won Mo; Park, Ik Jae; Yoo, Eun-Sang; Shin, Seong Sik; Kim, Ju Seong; Jung, Hyun Suk; Lee, Sangwook; Hong, Kug Sun

2013-11-01

347

Titanium dioxide dye-sensitized polyaniline solar cells  

NASA Astrophysics Data System (ADS)

A novel form of a dye-sensitized solar cell was investigated with in situ photopolymerization of aniline. Tris(4-carboxyphenyl)mono(4-aminophenyl) porphyrin (TC3APP) was successfully synthesized and used as a sensitizer. Nanoparticulate TiO2 electrodes were prepared from 25 nm size TiO 2 particles (P25); in addition, commercial TiO2 electrodes from Solaronix and INAP were used. Electrochemically polymerized polyaniline films were used as a counterelectrode. Aniline gel as an electrolyte solution was composed of (1S)-(+)-10-camphorsulfonic acid (CSA), lithium perchlorate (LiClO4), polyethylene oxide (PEO), and aniline as solvent. Morphology study of TiO2 electrodes and electropolymerized polyaniline films proceeded with atomic force microscopy (AFM) and scanning electron microscopy (SEM). Results showed that TiO2 electrodes have a highly porous and well connected structure and polyaniline film is composed of a waxy surface and bush-like structure. The conductive emeraldine salt form of polyaniline was confirmed with UV absorption spectroscopy. Adsorption study of TC3APP on TiO2 electrode suggested that most of the adsorption proceeded in 6 hours after the immersion of TiO 2 electrode in TC3APP solution. Greater amounts of TC 3APP were adsorbed on TiO2 electrode in the presence of deoxycholic acid as coadsorber. Photopolymerization proceeded in a sandwiched solar cell with TC 3APP-adsorbed TiO2 electrode and polyaniline counterelectrode including aniline gel. Photocurrent was observed with zero bias voltage. Photocurrent as a function of time was composed of two stages: (1) photoelectropolymerization of polyaniline and (2) conduction of photoelectrons as in a typical solar cell. The current-voltage measurement produced Voc = 0.6 V, J sc = 0.23 mA/cm2, FF = 0.78, and eta = 0.74% under 14.6 mW/cm2 of light intensity. Spectral study and action spectrum confirm that TC3APP is responsible for the photocurrent upon absorption of visible light, and some absorption by polyaniline film beyond 650 nm also participates in the generation of photocurrent. Each component of the solar cell plays an important role to complete this solar cell system.

Kim, Hooi-Sung

2005-11-01

348

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

NASA Astrophysics Data System (ADS)

The killing effect of nitrogen-doped titanium dioxide (N-TiO2) nanoparticles on human cervical carcinoma (HeLa) cells by visible light photodynamic therapy (PDT) was higher than that of TiO2 nanoparticles. To study the mechanism of the killing effect, the reactive oxygen species produced by the visible-light-activated N-TiO2 and pure-TiO2 were evaluated and compared. The changes of the cellular parameters, such as the mitochondrial membrane potential (MMP), intracellular Ca2+, and nitrogen monoxide (NO) concentrations after PDT were measured and compared for N-TiO2- and TiO2-treated HeLa cells. The N-TiO2 resulted in more loss of MMP and higher increase of Ca2+ and NO in HeLa cells than pure TiO2. The cell morphology changes with time were also examined by a confocal microscope. The cells incubated with N-TiO2 exhibited serious distortion and membrane breakage at 60 min after the PDT.

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

2013-02-01

349

Significantly accelerated osteoblast cell growth on aligned TiO2 nanotubes  

E-print Network

nanotubes; osteoblast cell; adhesion; accel- erated cell growth INTRODUCTION Titanium (Ti) and its alloys and dental surgery.1­3 The initial interac- tion between a metal implant and a growing bone plays have been widely used as implantation materials that can provide direct physi- cal bonding

Daraio, Chiara

350

The nanoscale geometry of TiO2 nanotubes influences the osteogenic differentiation of human adipose-derived stem cells by modulating H3K4 trimethylation.  

PubMed

Nanostructured materials can direct stem cell lineage commitment solely by their various, but controllable, geometric cues, which would be very important for their future application in bone tissue engineering and bone regeneration. However, the mechanisms by which nano-geometric cues dictate the osteogenic differentiation of stem cells remain unclear. Epigenetics is central to cellular differentiation, a process that regulates heritable and long-lasting alterations in gene expression without changing the DNA sequence. Here, we explored the varied osteogenic behaviors of human adipose-derived stem cells (hASCs) on titanium dioxide (TiO2) nanotube arrays of different diameters. Both in vitro and in vivo studies demonstrated that the nanoscale geometry influenced cellular differentiation and TiO2 nanotubes with a diameter of 70 nm was the optimal dimension for the osteogenic differentiation of hASCs. Moreover, we observed that TiO2 nanotubes promoted the osteogenic differentiation of hASCs by upregulating methylation level of histone H3 at lysine 4 (H3K4) in the promoter regions of osteogenic genes Runx2 and osteocalcin, by inhibiting demethylase retinoblastoma binding protein 2 (RBP2). These results revealed, for the first time, the epigenetic mechanism by which nanotopography directs stem cell fate. PMID:25468371

Lv, Longwei; Liu, Yunsong; Zhang, Ping; Zhang, Xiao; Liu, Jianzhang; Chen, Tong; Su, Penglei; Li, Hongyi; Zhou, Yongsheng

2015-01-01

351

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

2014-11-13

352

Biological impacts of TiO 2 on human lung cell lines A549 and H1299: particle size distribution effects  

Microsoft Academic Search

Increasing use of titanium dioxide (TiO2) nanoparticles in many commercial applications has led to emerging concerns regarding the safety and environmental impact\\u000a of these materials. In this study, we have investigated the biological impact of nano-TiO2 (with particle primary size of 20 nm Aeroxide P25) on human lung cell lines in vitro and also the effect of particle size\\u000a distribution on

Roslyn Tedja; Christopher Marquis; May Lim; Rose Amal

353

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

354

Nanocomposite enables sensitized solar cell  

NASA Astrophysics Data System (ADS)

Dye Sensitized solar cells (DSSCs) are a promising candidate for next generation photovoltaic panels due to their low cost, easy fabrication process, and relative high efficiency. Despite considerable effort on the advancement of DSSCs, the efficiency has been stalled for nearly a decade due to the complex interplay among various DSSC components. DSSCs consist of a photoanode on a conducting substrate, infiltrated dye for light absorption and electron injection, and an electrolyte to regenerate the dye. On the photoanode is a high band-gap semiconducting material, primarily of a nanostructure morphology of titanium (II) dioxide (TiO2), dye molecules whose molar absorption is typically in the visible spectrum, are adsorbed onto the surface of TiO 2. To improve the current DSSCs, there are many parameters that can be investigated. In a conventional DSSC, a thick semiconducting layer such as the nanoparticle TiO2 layer induces charge separation efficiently while concurrently increasing the charge transport distance, leading the cell to suffer from more charge recombination and deterioration in charge collection efficiency. To improve on this limitation, TiO2 nanowires (NW) and nanotubes (NT) are explored to replace the nanoparticle photoanode. One-dimensional nanostructures are known for the excellent electron transport properties as well as maintaining a relatively high surface area. Hence one of the focuses of this thesis explores at using different morphologies and composition of TiO2 nanostructures to enhance electron collection efficiency. Another challenge in conventional DSSCs is the limit in light absorption of solar irradiation. Dyes are limited to absorption only in the visible range, and have a low molar absorption coefficient in the near infrared (NIR). Tuning dyes is extremely complicated and may have more disadvantages than simply by extending light harvesting. Therefore our strategy is to incorporate quantum dots to replace the dye, as well as prepare a cell for the possibility of co-sensitization, thereby extending the absorption of light in the visible and NIR. The first phase of the thesis involves the synthesis and characterization of the materials used for the cell. We successfully synthesized TiO2 nanowires and nanotubes and characterized them for the use as the photoanode. Both one-dimensional structures proved to have low resistivity, chemical stability, and high density. We also synthesized lead (II) sulfide (PbS) quantum dots (QDs) and explored at modifying their diameter in order to properly control their light harvesting potential into the NIR region. The electron transport kinetics proved to be faster in one-dimensional nanostructure due to their high crystallinity order and reduced elastic scattering of the electrons during transport. Furthermore, quantum dots were synthesized such that their band-gap allowed for the absorption of NIR light. This result extended the harvesting potential of our solar cell and suggests the possibility for co-sensitization in DSSCs using dye molecules and quantum dots. Hence, the focus of this thesis work is to systematically explore a transformative way to fundamentally enhance charge transport and extend light absorption by in the incorporation of two sensitizing agents.

Phuyal, Dibya D.

355

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

356

Network of flatband solar cells as a model for solid-state nanostructured solar cells  

Microsoft Academic Search

Nanostructured solar cells are too complex for standard modeling. Here, we decouple the effects at a microscopic (nm) scale from those at a macroscopic (mum) scale. The three-dimensional nanoporous geometry is simplified to a quasiperiodic nm-scale ordering of ``unit cells,'' each consisting of a TiO2 sphere and its p-semiconductor or dye\\/p-conductor shell. It is shown that, due to the periodic

Marc Burgelman; Catelijne Grasso

2004-01-01

357

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

358

Increasing the Conversion Efficiency of Dye-Sensitized TiO2 Photoelectrochemical Cells by Coupling to Photonic Crystals  

E-print Network

inverse opals or disordered scattering layers to conventional nanocrystalline TiO2 films has been inverse opals of varying stop band wavelengths and at disordered titania films was compared to the IPCE the inverse opal structures, is responsible for the bulk of the gain in IPCE. Several mechanisms of light

359

Solar Cells  

NASA Technical Reports Server (NTRS)

The Heat Exchanger Method (HEM) produces high efficiency crystal ingots in an automated well-insulated furnace offering low equipment, labor and energy costs. The "grown" silicon crystals are used to make solar cells, or photovoltaic cells which convert sunlight directly into electricity. The HEM method is used by Crystal Systems, Inc. and was developed under a NASA/Jet Propulsion Laboratory contract. The square wafers which are the result of the process are sold to companies manufacturing solar panels.

1983-01-01

360

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

361

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

362

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

363

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

364

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

365

Comparison of the photovoltaic efficiency on DSSC for nanometer sized TiO 2 using a conventional sol–gel and solvothermal methods  

Microsoft Academic Search

When the two types of TiO2 coatings prepared by sol–gel and solvothermal methods were applied to dye-sensitized solar cell (DSSC) in this study, the energy conversion efficiency of the solvothermal-modified TiO2 was considerably higher than that on the sol–gel modified TiO2; approximately 8.51 (solvothermal) and 5.93% (sol–gel) with the N719 dye under 100mW\\/cm2 of simulated sunlight, respectively. These results are

Yeji Lee; Jinho Chae; Misook Kang

2010-01-01

366

Solar photo-Fenton using peroxymonosulfate for organic micropollutants removal from domestic wastewater: Comparison with heterogeneous TiO2 photocatalysis.  

PubMed

This work aims at decontaminating biologically treated domestic wastewater effluents from organic micropollutants by sulfate radical based (SO4(-)) homogeneous photo-Fenton involving peroxymonosulfate as an oxidant, ferrous iron (Fe(II)) as a catalyst and simulated solar irradiation as a light source. This oxidative system was evaluated by using several probe compounds belonging to pesticides (bifenthrin, mesotrione and clothianidin) and pharmaceuticals (diclofenac, sulfamethoxazole and carbamazepine) classes and its kinetic efficiency was compared to that to the well known UV-Vis/TiO2 heterogeneous photocatalysis. Except for carbamazepine, apparent kinetic rate constants were always 10 times higher in PMS/Fe(II)/UV-Vis than in TiO2/UV-Vis system and more than 70% of total organic carbon abatement was reached in less than one hour treatment. Hydroxyl radical (OH) and SO4(-) reactivity was investigated using mesotrione as a probe compound through by-products identification by liquid chromatography-high resolution-mass spectrometry and transformation pathways elucidation. In addition to two OH based transformation pathways, a specific SO4(-) transformation pathway which first involved degradation through one electron transfer oxidation processes followed by decarboxylation were probably responsible for mesotrione degradation kinetic improvement upon UV-Vis/PMS/Fe(II) system in comparison to UVVis/TiO2 system. PMID:25108605

Ahmed, Moussa Mahdi; Brienza, Monica; Goetz, Vincent; Chiron, Serge

2014-12-01

367

Chemical capacitance of nanoporous-nanocrystalline TiO2 in a room temperature ionic liquid.  

PubMed

The electrochemical behaviour of nanoporous TiO(2) in a room temperature ionic liquid (RTIL), 1-ethyl-3-methylimidazolium bis((trifluoromethyl)sulfonyl)amide (EMITFSI), was investigated by cyclic voltammetry (CV) and impedance spectroscopy. Exponentially rising currents in voltammetry were attributed to the charging/discharging of electrons in the TiO(2) film and a charge transfer mechanism. The main features of the voltammetry and impedance followed the same trends in the ionic liquid as in other organic solvents and also in aqueous electrolytes. In the presence of lithium ions, the onset potential of the charge accumulation increased due to the change of the initial position of the TiO(2) conduction band. The results show that substitution of organic solvents contained in solar cells, supercapacitors or other electrochemical devices is in general feasible, though requires some adjustment in the electrolyte composition for optimal performance. PMID:16633668

Fabregat-Santiago, Francisco; Randriamahazaka, Hyacinthe; Zaban, Arie; Garcia-Cañadas, Jorge; Garcia-Belmonte, G; Bisquert, Juan

2006-04-21

368

Development of multilayered nanocrystalline TiO2 thin films for photovoltaic application  

NASA Astrophysics Data System (ADS)

Nanocrystalline multilayered thin films of TiO2 have been prepared to achieve high transparency in the wavelength range of 400-800 nm having good adhesion to the ITO substrate. TiO2 sol is synthesized through wet chemical route for making thin films by dip coating process. The layer wise optical characterization reveals higher band gap values of 3.45 eV, 3.32 eV for 2-layered and 3-layered films respectively while further depositions of thin layers followed by annealing treatment shows that the value of band gap approaches towards the bulk TiO2 considerable decrease in band gap with increase in thickness due to successive coatings of thin film is observed because of growth in crystal size as well as improving the grain contact on successive annealing treatments. Photo-conversion efficiency of the assembled solar cell is in the order of 7%.

Usha, K.; Mondal, B.; Sengupta, D.; Das, P.; Mukherjee, K.; Kumbhakar, P.

2014-04-01

369

Preparation of coaxial TiO 2\\/ZnO nanotube arrays for high-efficiency photo-energy conversion applications  

Microsoft Academic Search

A novel type of coaxial TiO2\\/ZnO nanotube arrays has been prepared by electrochemical method. The TiO2\\/ZnO nanotube arrays can be applied as highly efficient photoanodes in dye-sensitized solar cells (DSSC). Such photoanode benefits from the capability of high sensitizer loading offered by the high specific surface, and the direct conduction path through the aligned nanotubes. Moreover, the heterojunction at the

Yu-Long Xie; Zi-Xia Li; Zhu-Guo Xu; Hao-Li Zhang

2011-01-01

370

Synergistic effect of CdSe quantum dot sensitization and nitrogen doping of TiO(2) nanostructures for photoelectrochemical solar hydrogen generation.  

PubMed

We report the synthesis and photoelectrochemical (PEC) studies of TiO(2) nanoparticles and nanowires simultaneously doped with nitrogen and sensitized with CdSe quantum dots (QDs). These novel nanocomposite structures have been applied successfully as photoanodes for PEC hydrogen generation using Na(2)S and Na(2)SO(3) as sacrificial reagents. We observe significant enhanced photoresponse in these nanocomposites compared to N-doped TiO(2) or CdSe QD sensitized TiO(2). The enhancement is attributed to the synergistic effect of CdSe sensitization and N-doping that facilitate hole transfer/transport from CdSe to TiO(2) through oxygen vacancy states (V(o)) mediated by N-doping. The results demonstrate the importance of designing and manipulating the energy band alignment in composite nanomaterials for fundamentally improving charge separation and transport and thereby PEC properties. PMID:20102190

Hensel, Jennifer; Wang, Gongming; Li, Yat; Zhang, Jin Z

2010-02-10

371

Preparation of TiO 2 films using nanopowder synthesized by flat-flame chemical vapor condensation method for DSSCs  

Microsoft Academic Search

The preparation of TiO2 films using nanopowder synthesized by flat-flame chemical vapor condensation method, as the anodes of dye-sensitized solar cells (DSSCs), is investigated. The solar cell efficiency of the cell with anode made of the mixture of the synthesized nanopowder and the commercial submicron-sized powder is above 2.5%. The cells have characteristic current density–voltage curves with fill factor typically

Y. J. Chen; M. C. Hsu; Y. C. Cai

2010-01-01

372

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

373

Double-doped TiO2 nanoparticles as an efficient visible-light-active photocatalyst and antibacterial agent under solar simulated light  

NASA Astrophysics Data System (ADS)

Silver and nitrogen doped TiO2 nanoparticles (NPs) were synthesized via sol-gel method. The physicochemical properties of the achieved NPs were characterized by various methods including X-Ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and ultra violet-visible absorption spectroscopy (UV-vis). Both visible-light photocatalytic activity and antimicrobial properties were successfully demonstrated for the degradation of Rhodamine B (Rh. B.), as a model dye, and inactivation of Escherichia coli (E. coli), as a representative of microorganisms. The concentration of the employed dopant was optimized and the results revealed that the silver and nitrogen doped TiO2 NPs extended the light absorption spectrum toward the visible region and significantly enhanced the photodegradation of model dye and inactivation of bacteria under visible-light irradiation while double-doped TiO2 NPs exhibited highest photocatalytic and antibacterial activity compared with single doping. The significant enhancement in the photocatalytic activity and antibacterial properties of the double doped TiO2 NPs, under visible-light irradiation, can be attributed to the generation of two different electronic states acting as electron traps in TiO2 and responsible for narrowing the band gap of TiO2 and shifting its optical response from UV to the visible-light region.

Ashkarran, Ali Akbar; Hamidinezhad, Habib; Haddadi, Hedayat; Mahmoudi, Morteza

2014-05-01

374

Anatase TiO2 nanorod-decoration for highly efficient photoenergy conversion.  

PubMed

In recent studies of inorganic materials for energy applications, surface modification processes have been shown to be among the most effective methods to enhance the performance of devices. Here, we demonstrate a facile nano-decoration method which is generally applicable to anatase TiO2 nanostructures, as well as a nano-decorated hierarchical TiO2 nanostructure which improves the energy conversion efficiency of a dye-sensitized solar cell (DSSC). Using a facile sol-gel method, 0-D, 1-D, and 2-D type anatase TiO2 nanostructures were decorated with 200 nm long anatase TiO2 nanorods to create various hierarchical nanostructures. A structural analysis reveals that the branched nanorod has a highly crystalline anatase phase with anisotropic growth in the [001] longitudinal direction. When one of the hierarchical structures, a chestnut bur-like nanostructure, was employed in a dye-sensitized solar cell as a scattering layer, offering increased dye-loading properties, preserving a sufficient level of light-scattering ability and preserving superior charge transport and recombination properties as well, the energy conversion efficiency of the cell improved by 19% (from 7.16% to 9.09%) compared to a cell with a 0-D TiO2 sphere as a scattering layer. This generally applicable anatase nanorod-decorating method offers potential applications in various energy-conversion applications, especially in DSSCs, quantum-dot solar cells, photoelectrochemical water-splitting devices, photocatalysis, and lithium ion batteries. PMID:24114150

Kim, Dong Hoe; Seong, Won Mo; Park, Ik Jae; Yoo, Eun-Sang; Shin, Seong Sik; Kim, Ju Seong; Jung, Hyun Suk; Lee, Sangwook; Hong, Kug Sun

2013-12-01

375

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

376

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

E-print Network

, Feng-Qin Liue a State Key Laboratory of Rare Earth Materials Chemistry and Applications, Peking.-H. Huang). 0927-0248/02/$ - see front matter r 2002 Elsevier Science B.V. All rights reserved. PII: S 0 9 2

Huang, Yanyi

377

The effect of TiCl4 treatment on the efficiency of dye sensitized solar cell  

NASA Astrophysics Data System (ADS)

Dye sensitized solar cells (DSSC) are the new generation of solar cells that have their advantages such as transparency, flexibility and low cost production. This has certainly attracted researchers in the field of green technology to further develop DSSC. The focus is on the efficiency, as it is low at this point of time, as compared to silicon based solar cells. In this paper, the effect of TiCl4 treatment on the efficiency of DSSC by treating the conducting glass and TiO2 layer was studied and results showed that the TiCl4 treatment on the conducting glass and the printed TiO2 film increased the efficiency from 3.45% to 4.43%. The TiO2 layer was characterized by using FESEM and AFM and the efficiency of the DSSC was measured by using the sunlight simulator.

Ardakani, Seyed Esmaeil Mahdavi; Singh, Balbir Singh Mahinder; Mohammed, Norani Muti

2014-10-01

378

Layered insulator hexagonal boron nitride for surface passivation in quantum dot solar cell  

NASA Astrophysics Data System (ADS)

Single crystalline, two dimensional (2D) layered insulator hexagonal boron nitride (h-BN), is demonstrated as an emerging material candidate for surface passivation on mesoporous TiO2. Cadmium selenide (CdSe) quantum dot based bulk heterojunction (BHJ) solar cell employed h-BN passivated TiO2 as an electron acceptor exhibits photoconversion efficiency ˜46% more than BHJ employed unpassivated TiO2. Dominant interfacial recombination pathways such as electron capture by TiO2 surface states and recombination with hole at valence band of CdSe are efficiently controlled by h-BN enabled surface passivation, leading to improved photovoltaic performance. Highly crystalline, confirmed by transmission electron microscopy, dangling bond-free 2D layered h-BN with self-terminated atomic planes, achieved by chemical exfoliation, enables efficient passivation on TiO2, allowing electronic transport at TiO2/h-BN/CdSe interface with much lower recombination rate compared to an unpassivated TiO2/CdSe interface.

Shanmugam, Mariyappan; Jain, Nikhil; Jacobs-Gedrim, Robin; Xu, Yang; Yu, Bin

2013-12-01

379

Large-diameter titanium dioxide nanotube arrays as a scattering layer for high-efficiency dye-sensitized solar cell  

PubMed Central

Large-sized titanium dioxide (TiO2) nanotube arrays with an outer diameter of approximately 500 nm have been successfully synthesized by potentiostatic anodization at 180 V in a used electrolyte with the addition of 1.5 M lactic acid. It is found that the synthesized large-diameter TiO2 nanotube array shows a superior light scattering ability, which can be used as a light scattering layer to significantly enhance the efficiency of TiO2 nanoparticle-based dye-sensitized solar cells from 5.18% to 6.15%. The remarkable light scattering ability makes the large-diameter TiO2 nanotube array a promising candidate for light management in dye-sensitized solar cells (DSSCs). PMID:25114652

2014-01-01

380

Titanium dioxide/calcium fluoride nanocrystallite for efficient dye-sensitized solar cell. A strategy of enhancing light harvest  

NASA Astrophysics Data System (ADS)

Enhancement of light harvest for dye excitation is a persistent objective in dye-sensitized solar cell (DSSC). We present here the fabrication of titanium dioxide/calcium fluoride (TiO2/CaF2) photoanodes for efficient DSSC applications. Owing to the interference effect of incident light beams reflected from TiO2/CaF2 and CaF2/electrolyte interfaces, the light intensity and therefore dye excitation have been markedly enhanced. The crystal structure and therefore photovoltaic performance are optimized by adjusting CaF2 dosage. A maximum power conversion efficiency of 7.66% is measured from the DSSC employing TiO2/0.5 wt% CaF2 nanocrystallite in comparison with 6.02% for the solar cell with pristine TiO2 anode.

Wang, Zubin; Tang, Qunwei; He, Benlin; Chen, Xiaoxu; Chen, Haiyan; Yu, Liangmin

2015-02-01

381

Mechanism of degradation of electrolyte solutions for dye-sensitized solar cells under ultraviolet light irradiation  

NASA Astrophysics Data System (ADS)

We studied the mechanism of the degradation of I-/I3--containing electrolyte solutions for dye-sensitized solar cells under UV light irradiation. The yellow electrolyte solutions underwent achromatization during irradiation, indicating the reduction of I3-. We propose a mechanism involving the production of holes in TiO2, reaction of the holes with solvent molecules, and subsequent reduction of I3- by electrons remaining in the TiO2. Although the quantum yield of the photodegradation reaction is estimated to be low (3 × 10-3), this reaction can nevertheless be expected to affect the long-term stability of dye-sensitized solar cell devices.

Nakajima, Shohei; Katoh, Ryuzi

2015-01-01

382

Hybrid micro/nano-topography of a TiO2 nanotube-coated commercial zirconia femoral knee implant promotes bone cell adhesion in vitro.  

PubMed

Various approaches have been studied to engineer the implant surface to enhance bone in-growth properties, particularly using micro- and nano-topography. In this study, the behavior of osteoblast (bone) cells was analyzed in response to a titanium oxide (TiO2) nanotube-coated commercial zirconia femoral knee implant consisting of a combined surface structure of a micro-roughened surface with the nanotube coating. The osteoblast cells demonstrated high degrees of adhesion and integration into the surface of the nanotube-coated implant material, indicating preferential cell behavior on this surface when compared to the bare implant. The results of this brief study provide sufficient evidence to encourage future studies. The development of such hierarchical micro- and nano-topographical features, as demonstrated in this work, can provide insightful designs for advanced bone-inducing material coatings on ceramic orthopedic implant surfaces. PMID:23623092

Frandsen, Christine J; Noh, Kunbae; Brammer, Karla S; Johnston, Gary; Jin, Sungho

2013-07-01

383

Hybrid micro/nano-topography of a TiO2 nanotube-coated commercial zirconia femoral knee implant promotes bone cell adhesion in vitro  

PubMed Central

Various approaches have been studied to engineer the implant surface to enhance bone in-growth properties, particularly using micro- and nano- topography. In this study, the behavior of osteoblast (bone) cells was analyzed in response to a titanium oxide (TiO2) nanotube-coated commercial zirconia femoral knee implant consisting of a combined surface structure of a micro-roughened surface with the nanotube coating. The osteoblast cells demonstrated high degrees of adhesion and integration into the surface of the nanotube-coated implant material, indicating preferential cell behavior on this surface when compared to the bare implant. The results of this brief study provide sufficient evidence to encourage future studies. The development of such hierarchical micro and nano topographical features, as demonstrated in this work, can provide for insightful designs for advanced bone-inducing material coatings on ceramic orthopedic implant surfaces. PMID:23623092

Frandsen, Christine J.; Noh, Kunbae; Brammer, Karla S.; Johnston, Gary; Jin, Sungho

2014-01-01

384

Sub 150 °C processed meso-superstructured perovskite solar cells with enhanced efficiency (presentation video)  

NASA Astrophysics Data System (ADS)

The ability to process amorphous or polycrystalline solar cells at low temperature (<150 °C) opens many possibilities for substrate choice and monolithic multijunction solar cell fabrication. Organometal trihalide perovskite solar cells have evolved rapidly over the last two years, and the CH3NH3PbX3 (X= Cl, I or Br) material is processed at low temperature. Until now however, the most efficient solar cells have employed 500 ºC sintered TiO2 compact layers as charge selective contacts. With our optimized formulation we demonstrate full sun solar power conversion efficiencies exceeding 16 % in an all low temperature processed solar cell.

Wojciechowski, Konrad; Saliba, Michael; Leijtens, Tomas; Abate, Antonio; Snaith, Henry J.

2014-10-01

385

Graphene frameworks promoted electron transport in quantum dot-sensitized solar cells.  

PubMed

Graphene frameworks (GFs) were incorporated into TiO2 photoanode as electron transport medium to improve the photovoltaic performance of quantum dot-sensitized solar cells (QDSSCs) for their excellent conductivity and isotropic framework structure that could permit rapid charge transport. Intensity modulated photocurrent/photovoltage spectroscopy and electrochemical impedance spectroscopy results show that the electron transport time (?(d)) of 1.5 wt % GFs/TiO2 electrode is one-fifth of that of the TiO2 electrode, and electron lifetime (?(n)) and diffusion path length (Ln) are thrice those of the TiO2 electrode. Results also revealed that the GFs/TiO2 electrode has a shorter electron transport time (?(d)), as well as longer electron lifetime (?(n)) and diffusion path length (Ln), than conventional 2D graphene sheets/TiO2 electrode, thus indicating that GFs could promote rapid electron transfer in TiO2 photoanodes. Photocurrent-voltage curves demonstrated that when incorporating 1.5 wt % GFs into TiO2 photoanode, a maximum power conversion efficiency of 4.2% for QDSSCs could be achieved. This value was higher than that of TiO2 photoanode and 2D graphene sheets/TiO2 electrode. In addition, the reasons behind the sensitivity of photoelectric conversion efficiency to the graphene concentration in the TiO2 were also systematically investigated. Our results provide a basic understanding of how GFs can efficiently promote electron transport in TiO2-based solar cells. PMID:25075630

Zhu, Yanyan; Meng, Xin; Cui, Huijuan; Jia, Suping; Dong, Jianhui; Zheng, Jianfeng; Zhao, Jianghong; Wang, Zhijian; Li, Li; Zhang, Li; Zhu, Zhenping

2014-08-27

386

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

SciTech Connect

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

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

2013-01-01

387

CdS and CdSe quantum dot co-sensitized nanocrystalline TiO2 electrode: Quantum dot distribution, thickness optimization, and the enhanced photovoltaic performance  

NASA Astrophysics Data System (ADS)

The anatase TiO2 nanoparticle films with different thicknesses have been fabricated through screen printing method, and CdS and CdSe quantum dots (QDs) have been deposited on TiO2 films in turn through successive ionic layer adsorption and reaction (SILAR) method. It has been found that the amount of QDs decreases significantly and the size of QDs increases obviously with the depth increasing in TiO2 nanoparticle films, and the size distribution of QDs shifts to large-size direction with the TiO2 film thickness increasing. Furthermore, a qualitative model of CdS/CdSe quantum dot distribution in TiO2 nanoparticle films has been obtained. After optimizing the TiO2 film thickness, the quantum dot-sensitized solar cells (QDSCs) with about 10 ?m thick nanocrystalline TiO2 electrodes and Pt counter electrodes have reached relatively high power conversion efficiencies of 3.26 ± 0.10% under one sun illumination (100 mW cm-2, AM 1.5 G).

Wang, Shimao; Dong, Weiwei; Fang, Xiaodong; Wu, Suzhen; Tao, Ruhua; Deng, Zanhong; Shao, Jingzhen; Hu, Linhua; Zhu, Jun

2015-01-01

388

Effects of 1064 nm laser on the structural and optical properties of nanostructured TiO2 thin film  

NASA Astrophysics Data System (ADS)

TiO2 thin film has been widely used as photoelectrode in dye-sensitized solar cells. It can also be used in quantum dot synthesized solar cells. Study of its effects in different spectrum of light is important for its use in solar cells. We have reported effects of 1064 nm laser on the surface morphology, structural and optical properties of nanostructured TiO2 thin film deposited on glass substrates using sol-gel spin coating technique. Q-Switched Nd:YAG pulsed laser at various power densities is used in this study. Surface morphology of the film is investigated using X-ray diffraction (XRD) and atomic force microscopy technique. The XRD pattern of as deposited TiO2 thin film is amorphous and after laser exposure it became TiO2 anatase structure. Atomic force microscopy of the crystalline TiO2 thin film shows that the grain size increases by increasing laser power density. The calculations of the band gap are carried out from UV/Visible spectroscopy measurements with JASCO spectrometer. For laser power density of 25 MW/cm2 there is an increase in the transmission and it decreases at the value of 38 MW/cm2 and band gap decreases with increasing laser power density. Photoluminescence spectra of the crystalline TiO2 thin film indicate two broad peaks in the range of 415 and 463 nm, one for band gap peak (415 nm) and other for oxygen defect during film deposition process.

Aslam Farooq, W.; Atif, M.; Ali, Syed Mansoor; Fatehmulla, Amanullah; Aslam, M.

2014-09-01

389

Chronic TiO2 nanoparticle exposure to a benthic organism, Hyalella azteca: Impact of solar UV radiation and material surface coatings on toxicity  

EPA Science Inventory

The present study examined the chronic toxicity of TiO2 nanoparticles (nano-TiO2) to a representative benthic species, Hyalella azteca, using an industry standard, P25, and a coated nano-TiO2 used in commercial products. There is limited information on the chronic effects of nano...

390

Kelvin probe force microscopy of nanocrystalline TiO2 photoelectrodes.  

PubMed

Dye-sensitized solar cells (DSCs) provide a promising third-generation photovoltaic concept based on the spectral sensitization of a wide-bandgap metal oxide. Although the nanocrystalline TiO2 photoelectrode of a DSC consists of sintered nanoparticles, there are few studies on the nanoscale properties. We focus on the microscopic work function and surface photovoltage (SPV) determination of TiO2 photoelectrodes using Kelvin probe force microscopy in combination with a tunable illumination system. A comparison of the surface potentials for TiO2 photoelectrodes sensitized with two different dyes, i.e., the standard dye N719 and a copper(I) bis(imine) complex, reveals an inverse orientation of the surface dipole. A higher surface potential was determined for an N719 photoelectrode. The surface potential increase due to the surface dipole correlates with a higher DSC performance. Concluding from this, microscopic surface potential variations, attributed to the complex nanostructure of the photoelectrode, influence the DSC performance. For both bare and sensitized TiO2 photoelectrodes, the measurements reveal microscopic inhomogeneities of more than 100 mV in the work function and show recombination time differences at different locations. The bandgap of 3.2 eV, determined by SPV spectroscopy, remained constant throughout the TiO2 layer. The effect of the built-in potential on the DSC performance at the TiO2/SnO2:F interface, investigated on a nanometer scale by KPFM measurements under visible light illumination, has not been resolved so far. PMID:23844348

Henning, Alex; Günzburger, Gino; Jöhr, Res; Rosenwaks, Yossi; Bozic-Weber, Biljana; Housecroft, Catherine E; Constable, Edwin C; Meyer, Ernst; Glatzel, Thilo

2013-01-01

391

Characterization of siloxane adsorbates covalently attached to TiO2  

NASA Astrophysics Data System (ADS)

Siloxanes with the general formula R-(CH2)n-Si-(OR')3 form durable bonds with inorganic materials upon hydrolysis of labile -OR' groups, and serve as robust coupling agents between organic and inorganic materials. In the field of dye-sensitized solar cells, functionalization of TiO2 thin-films with siloxane adsorbates has been shown to be useful as a surface-passivation technique that hinders recombination processes and improves the overall efficiency of light-to-electricity conversion. However, the attachment of siloxane adsorbates on TiO2 surfaces still remains poorly understood at the molecular level. In this paper, we report the characterization of 3-(triethoxysilyl) propionitrile (TPS) adsorbates, covalently attached onto TiO2 surfaces. We combine synthetic methods based on chemical vapor deposition, Fourier transform (FT) infrared (IR) spectroscopy and electronic structure calculations based on density functional theory (DFT). We predict that trifunctional siloxanes form only 2 covalent bonds, in a 'bridge' mode with adjacent Ti4+ ions on the TiO2 surface, leaving 'dangling' alkoxy groups on the surface adsorbates. Our findings are supported by the observation of a prominent fingerprint band at 1000-1100 cm-1, assigned to Si-O-C stretching modes, and by calculations of binding enthalpies at the DFT B3LYP/(LACVP/6-31G**) level of theory indicating that the 'bridge' binding (?Hb= -55 kcal mol-1) is more stable than 'tripod' motifs (?Hb= -45 kcal mol-1) where siloxanes form 3 covalent bonds with the TiO2 surface. The alkoxysiloxane groups are robust under heat and water treatment and are expected to be particularly relevant for analytical methods since they could be exploited for immobilizing other functionalities onto the TiO2 surfaces.

Iguchi, Nobuhito; Cady, Clyde; Snoeberger, Robert C., III; Hunter, Bryan M.; Sproviero, Eduardo M.; Schmuttenmaer, Charles A.; Crabtree, Robert H.; Brudvig, Gary W.; Batista, Victor S.

2008-08-01

392

Kelvin probe force microscopy of nanocrystalline TiO2 photoelectrodes  

PubMed Central

Summary Dye-sensitized solar cells (DSCs) provide a promising third-generation photovoltaic concept based on the spectral sensitization of a wide-bandgap metal oxide. Although the nanocrystalline TiO2 photoelectrode of a DSC consists of sintered nanoparticles, there are few studies on the nanoscale properties. We focus on the microscopic work function and surface photovoltage (SPV) determination of TiO2 photoelectrodes using Kelvin probe force microscopy in combination with a tunable illumination system. A comparison of the surface potentials for TiO2 photoelectrodes sensitized with two different dyes, i.e., the standard dye N719 and a copper(I) bis(imine) complex, reveals an inverse orientation of the surface dipole. A higher surface potential was determined for an N719 photoelectrode. The surface potential increase due to the surface dipole correlates with a higher DSC performance. Concluding from this, microscopic surface potential variations, attributed to the complex nanostructure of the photoelectrode, influence the DSC performance. For both bare and sensitized TiO2 photoelectrodes, the measurements reveal microscopic inhomogeneities of more than 100 mV in the work function and show recombination time differences at different locations. The bandgap of 3.2 eV, determined by SPV spectroscopy, remained constant throughout the TiO2 layer. The effect of the built-in potential on the DSC performance at the TiO2/SnO2:F interface, investigated on a nanometer scale by KPFM measurements under visible light illumination, has not been resolved so far. PMID:23844348

Günzburger, Gino; Jöhr, Res; Rosenwaks, Yossi; Bozic-Weber, Biljana; Housecroft, Catherine E; Constable, Edwin C; Meyer, Ernst; Glatzel, Thilo

2013-01-01

393

Interplay between transparency and efficiency in dye sensitized solar cells.  

PubMed

In this paper we analyze the interplay between transparency and efficiency in dye sensitized solar cells by varying fabrication parameters such as the thickness of the nano-crystalline TiO(2) layer, the dye loading and the dye type. Both transparency and efficiency show a saturation trend when plotted versus dye loading. By introducing the transparency-efficiency plot, we show that the relation between transparency and efficiency is linear and is almost independent on the TiO(2) thickness for a certain thickness range. On the contrary, the relation between transparency and efficiency depends strongly on the type of the dye. Moreover, we show that co-sensitization techniques can be effectively used to access regions of the transparency-efficiency space that are forbidden for single dye sensitization. The relation found between transparency and efficiency (T&E) can be the general guide for optimization of Dye Solar Cells in building integration applications. PMID:23481782

Tagliaferro, Roberto; Colonna, Daniele; Brown, Thomas M; Reale, Andrea; Di Carlo, Aldo

2013-02-11

394

Combined strategy to realize efficient photoelectrodes for low temperature fabrication of dye solar cells.  

PubMed

We implemented a low-temperature approach to fabricate efficient photoanodes for dye-sensitized solar cells, which combines three different nanoarchitectures, namely, a highly conductive and highly transparent AZO film, a thin TiO2-blocking layer, and a mesoporous TiO2 nanorod-based working electrode. All the components were processed at T?200°C. Both the AZO and the TiO2 blocking layers were deposited by reactive sputtering, whereas the TiO2 nanorods were synthesized by surfactant-assisted wet-chemical routes and processed into photoelectrodes in which the native geometric features assured uniform mesoporous structure with effective nanocrystal interconnectivity suitable to maximize light harvesting and electron diffusion. Because of the optimized structure of the TiO2-blocking/AZO bilayer, and thanks to the good adhesion of the TiO2 nanorods over it, a significant enhancement of the charge recombination resistance was demonstrated, this laying on the basis of the outstanding power conversion efficiency achievable through the use of this photoanode's architecture: a value of 4.6% (N719) was achieved with a 4-?m-thick electrode processed at T=200°C. This value noticeably overcomes the current literature limit got on AZO-based cells (N719), which instead use Nb-doped and thicker blocking layers, and thicker nanostructured photoanodes, which have been even sintered at higher temperatures (450-500°C). PMID:24694230

Alberti, A; De Marco, L; Pellegrino, G; Condorelli, G G; Giannuzzi, R; Scarfiello, R; Manca, M; Spinella, C; Gigli, G; La Magna, A

2014-05-14

395

Linker-Free Deposition and Adhesion of Photosystem I onto Nanostructured TiO2 for Biohybrid Photoelectrochemical Cells.  

PubMed

Photosystem I (PSI) from oxygenic photosynthetic organisms is an attractive sensitizer for nano-biohybrid solar cells as it has a combined light-harvesting and reaction center in one protein complex and operates at a quantum yield close to one in biological systems. Using a linker-free deposition technique enabled by an electrospray system, PSI was coupled to 1-D nanostructured titanium dioxide thin films to fabricate an electrode for a photoelectrochemical cell. After deposition, the surfactant in the PSI aggregate was dissolved in the surfactant-free electrolyte, ensuring that partly hydrophobic PSI was not resuspended and stayed in contact with titanium dioxide. A maximum current density of 4.15 mA cm(-2) was measured after 10 min of electrospray deposition, and this is the highest current density reported so far for PSI-based photoelectrochemical cells. The high current is attributed to 1D nanostructure of titanium dioxide and orientation of the PSI onto the surface, which allows easy transfer of electrons. PMID:25540979

Shah, Vivek B; Henson, William R; Chadha, Tandeep S; Lakin, Gerard; Liu, Haijun; Blankenship, Robert E; Biswas, Pratim

2015-02-10

396

2D ZnIn(2)S(4) nanosheet/1D TiO(2) nanorod heterostructure arrays for improved photoelectrochemical water splitting.  

PubMed

We report the fabrication of 2D ZnIn2S4 nanosheet/1D TiO2 nanorod heterojunction arrays by a facile hydrothermal process and their use as photoelectrodes in a photoelectrochemical (PEC) cell for high-performance solar water splitting. The morphology, microstructure, and phase of pristine TiO2 and 2D ZnIn2S4 nanosheet/1D TiO2 nanorod heterojunction arrays were characterized in detail. PEC measurements showed that 2D/1D heterojunction arrays offered enhanced photocurrent density (3 times higher than that of pristine TiO2), negatively shifted onset potential from 0.05 to -0.53 V, and high light on/off cycle stability. Electrochemical impedance investigation attested to a significant improvement of the interface electron transfer kinetics in this heterojunction, thus facilitating electron-hole separation, transfer, and collection, which resulted in enhanced PEC properties. PMID:25225738

Liu, Qiong; Lu, Hao; Shi, Zhiwei; Wu, Fangli; Guo, Jun; Deng, Kaimo; Li, Liang

2014-10-01

397

Efficiency enhancements in Ag nanoparticles-SiO2-TiO2 sandwiched structure via plasmonic effect-enhanced light capturing  

PubMed Central

TiO2-SiO2-Ag composites are fabricated by depositing TiO2 films on silica substrates embedded with Ag nanoparticles. Enhancement of light absorption of the nanostructural composites is observed. The light absorption enhancement of the synthesized structure in comparison to TiO2 originated from the near-field enhancement caused by the plasmonic effect of Ag nanoparticles, which can be demonstrated by the optical absorption spectra, Raman scattering investigation, and the increase of the photocatalytic activity. The embedded Ag nanoparticles are formed by ion implantation, which effectively prevents Ag to be oxidized through direct contact with TiO2. The suggested incorporation of plasmonic nanostructures shows a great potential application in a highly efficient photocatalyst and ultra-thin solar cell. PMID:23402586

2013-01-01

398

Efficiency enhancements in Ag nanoparticles-SiO2-TiO2 sandwiched structure via plasmonic effect-enhanced light capturing  

NASA Astrophysics Data System (ADS)

TiO2-SiO2-Ag composites are fabricated by depositing TiO2 films on silica substrates embedded with Ag nanoparticles. Enhancement of light absorption of the nanostructural composites is observed. The light absorption enhancement of the synthesized structure in comparison to TiO2 originated from the near-field enhancement caused by the plasmonic effect of Ag nanoparticles, which can be demonstrated by the optical absorption spectra, Raman scattering investigation, and the increase of the photocatalytic activity. The embedded Ag nanoparticles are formed by ion implantation, which effectively prevents Ag to be oxidized through direct contact with TiO2. The suggested incorporation of plasmonic nanostructures shows a great potential application in a highly efficient photocatalyst and ultra-thin solar cell.

Xu, Jinxia; Xiao, Xiangheng; Stepanov, Andrey L.; Ren, Fen; Wu, Wei; Cai, Guangxu; Zhang, Shaofeng; Dai, Zhigao; Mei, Fei; Jiang, Changzhong

2013-02-01

399

Natural dye extract of lawsonia inermis seed as photo sensitizer for titanium dioxide based dye sensitized solar cells  

NASA Astrophysics Data System (ADS)

Natural dye extract of lawsonia inermis seed were used as photo sensitizer to fabricate titanium dioxide nanoparticles based dye sensitized solar cells. Pure titanium dioxide (TiO2) nanoparticles in anatase phase were synthesized by sol-gel technique and pre dye treated TiO2 nanoparticles were synthesized using modified sol-gel technique by mixing lawsone pigment rich natural dye during the synthesis itself. This pre dye treatment with natural dye has yielded colored TiO2 nanoparticles with uniform adsorption of natural dye, reduced agglomeration, less dye aggregation and improved morphology. The pure and pre dye treated TiO2 nanoparticles were subjected to structural, optical, spectral and morphological studies. Dye sensitized solar cells (DSSC) fabricated using the pre dye treated and pure TiO2 nanoparticles sensitized by natural dye extract of lawsonia inermis seed showed a promising solar light to electron conversion efficiency of 1.47% and 1% respectively. The pre dye treated TiO2 based DSSC showed an improved efficiency of 47% when compared to that of conventional DSSC.

Ananth, S.; Vivek, P.; Arumanayagam, T.; Murugakoothan, P.

2014-07-01

400

Natural dye extract of lawsonia inermis seed as photo sensitizer for titanium dioxide based dye sensitized solar cells.  

PubMed

Natural dye extract of lawsonia inermis seed were used as photo sensitizer to fabricate titanium dioxide nanoparticles based dye sensitized solar cells. Pure titanium dioxide (TiO2) nanoparticles in anatase phase were synthesized by sol-gel technique and pre dye treated TiO2 nanoparticles were synthesized using modified sol-gel technique by mixing lawsone pigment rich natural dye during the synthesis itself. This pre dye treatment with natural dye has yielded colored TiO2 nanoparticles with uniform adsorption of natural dye, reduced agglomeration, less dye aggregation and improved morphology. The pure and pre dye treated TiO2 nanoparticles were subjected to structural, optical, spectral and morphological studies. Dye sensitized solar cells (DSSC) fabricated using the pre dye treated and pure TiO2 nanoparticles sensitized by natural dye extract of lawsonia inermis seed showed a promising solar light to electron conversion efficiency of 1.47% and 1% respectively. The pre dye treated TiO2 based DSSC showed an improved efficiency of 47% when compared to that of conventional DSSC. PMID:24682058

Ananth, S; Vivek, P; Arumanayagam, T; Murugakoothan, P

2014-07-15

401

Adhesion of TiO2 nanotube arrays on transparent conducting substrates using CNT-TiO2 composite pastes  

NASA Astrophysics Data System (ADS)

Dye-sensitized solar cells (DSSCs) were fabricated using TiO2 nanotube arrays (NTAs) as the photoanodes, which were adhered onto transparent conducting glass substrates by a carbon nanotube (CNT)-TiO2 composite paste. The effect of the CNT contents on the DSSC performance was investigated by adjusting the ratios of CNTs to TiO2 in the paste. It was found that DSSC efficiencies firstly increased and then decreased with increasing the CNT contents. The optimized DSSC efficiency of 6.77% was achieved at a suitable CNT concentration (0.1 wt%), which was due to a balance of the electron transport and light harvesting.

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

2014-06-01

402

Optimal wavelength scale diffraction gratings for light trapping in solar cells  

NASA Astrophysics Data System (ADS)

Dielectric gratings are a promising method of achieving light trapping for thin crystalline silicon solar cells. In this paper, we systematically examine the potential performance of thin silicon solar cells with either silicon (Si) or titanium dioxide (TiO2) gratings using numerical simulations. The square pyramid structure with silicon nitride coating provides the best light trapping among all the symmetric structures investigated, with 89% of the expected short circuit current density of the Lambertian case. For structures where the grating is at the rear of the cell, we show that the light trapping provided by the square pyramid and the checkerboard structure is almost identical. Introducing asymmetry into the grating structures can further improve their light trapping properties. An optimized Si skewed pyramid grating on the front surface of the solar cell results in a maximum short circuit current density, Jsc, of 33.4 mA cm-2, which is 91% of the Jsc expected from an ideal Lambertian scatterer. An optimized Si skewed pyramid grating on the rear performs as well as a rear Lambertian scatterer and an optimized TiO2 grating on the rear results in 84% of the Jsc expected from an optimized Si grating. The results show that submicron symmetric and skewed pyramids of Si or TiO2 are a highly effective way of achieving light trapping in thin film solar cells. TiO2 structures would have the additional advantage of not increasing recombination within the cell.

Kong Chong, Teck; Wilson, Jonathan; Mokkapati, Sudha; Catchpole, Kylie R.

2012-02-01

403

Effects of electron beam irradiation on the photoelectrochemical properties of TiO2 film for DSSCs  

NASA Astrophysics Data System (ADS)

iO2 has been widely utilized for various industrial applications such as photochemical cells, photocatalysts, and electrochromic devices. The crystallinity and morphology of TiO2 films play a significant role in determining the overall efficiency of dye-sensitized solar cells (DSSCs). In this study, the preparation of nanostructured TiO2 films by electron beam irradiation and their characterization were investigated for the application of DSSCs. TiO2 films were exposed to 20-100 kGy of electron beam irradiation using 1.14 MeV energy acceleration with a 7.46 mA beam current and 10 kGy/pass dose rates. These samples were characterized using X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), and X-ray photoelectron spectroscopy (XPS) analysis. After irradiation, each TiO2 film was tested as a DSSC. At low doses of electron beam irradiation (20 kGy), the energy conversion efficiency of the film was approximately 4.0% under illumination of simulated sunlight with AM 1.5 G (100 mW/cm2). We found that electron beam irradiation resulted in surface modification of the TiO2 films, which could explain the observed increase in the conversion efficiency in irradiated versus non-irradiated films.

Kim, Hyun-Bin; Park, Dong-Won; Jeun, Joon-Pyo; Oh, Seung-Hwan; Nho, Young-Chang; Kang, Phil-Hyun

2012-08-01

404

Fabrication of nanostructured CIGS solar cells  

NASA Astrophysics Data System (ADS)

We present the work on Cu(In,Ga)(Se,S)2 based nanostructured solar cells based on nanowire arrays. CIGS as the light absorber for thin-film solar cells has been widely studied recently, due to its high absorption coefficient, long-term stability, and low-cost of fabrication. Recently, solution phase processed CIGS thin film solar cells attracted great attention due to their extremely low fabrication cost. However, the performance is lower than vacuum based thin films possibly due to higher density of defects and lower carrier mobility. On the other hand, one dimensional ordered nanostructures such as nanowires and nanorods can be used to make redial junction solar cells, where the orthogonality between light absorption and charge carrier separation can lead to enhanced PV performance. Since the charge carriers only need to traverse a short distance in the radial direction before they are separated at the heterojunction interface, the radial junction scheme can be more defect tolerant than their planar junction scheme. In this work, a wide band gap nanowire or nanotube array such as TiO2 is used as a scaffold where CIGS is conformally coated using solution phase to obtain a radial heterojunction solar cell. Their performance is compared that of the planar thin film solar cells fabricated with the same materials.

Zhang, Hongwang; Wang, Fang; Parry, James; Perera, Samanthe; Zeng, Hao

2012-02-01

405

Dye-sensitized solar cells based on free-standing titanium dioxide nanotube arrays  

NASA Astrophysics Data System (ADS)

Dye-sensitized solar cells (DSSCs) are photoelectrochemical cells using wide band gap nanoporous oxide semiconductors sensitized by dey molecules. DSSCs generally consist of photosensitive dye molecules and a titanium dioxide (TiO2) nanoparticle network. DSSCs convert light energy to electrical energy through photo-excitation of dye molecules anchored to the surface of TiO2 nanoparticles, electron injection and transport in the TiO 2 nanoparticle network. DSSCs attracted great attention due to their respectable efficiency with very low fabrication cost, good performance under diffuse light conditions, semi-transparency and multi color range possibilities, and the ability to be fabricated on flexible substrates. Its main efficiency limiting factor is the random hopping of electrons within the TiO2 nanoparticle network, which causes carrier trapping and recombination. The charge transport and collection can be enhanced by employing ordered nanostructures such as nanowire or nanotube arrays. However, DSSCs based on nanowire or nanotube arrays with power conversion efficiency higher than 11.18% achieved from the conventional DSSCs have yet to be demonstrated. This dissertation focuses on the development of DSSCs using highly crystalline free-standing TiO2 nanotube (FSTNT) arrays to enhance charge transport and collection, and hence, power conversion efficiency. TiO2 nanotube arrays were obtained by potentiostatic anodization of titanium foil in fluoride-based ethylene glycol electrolyte. TiO2 nanotube arrays were detached from the titanium foil by chemical etching and annealed at high temperatures to obtain highly crystalline anatase phase FSTNT arrays. DSSCs based on FSTNT arrays revealed high power conversion efficiency of 13.2% and short-circuit photocurrent density comparable to that of monocrystalline silicon solar cell.

Kim, Chaehyun

406

Photovoltaic effect of TiO2 thick films with an ultrathin BiFeO3 as buffer layer  

NASA Astrophysics Data System (ADS)

The photovoltaic (PV) effect of a bilayer anatase TiO2/BiFeO3 (BFO) film has been studied. The 20-nm ultrathin BFO layers were deposited on the fluorine-doped tin oxide (FTO) glass substrates by the chemical solution deposition method. An anatase TiO2 layer is deposited subsequently on the BFO surface via a screen-printing technique. It is found that the FTO/TiO2/Au cell exhibits negligible PV effect under solar exposure, while the one after introducing an ultrathin BFO film between TiO2 and FTO leads to a considerable PV effect with an open-circuit voltage of -0.58 V and a photocurrent density of 18.27 µA/cm2. The FTO/BiVO4 (BVO)/TiO2/Au cell was constructed to investigate the underlying mechanism for the observed effect. A negligible PV effect of the FTO/BVO/TiO2/Au cell indicates that the PV effect of the FTO/BFO/TiO2/Au cell arises mainly from a built-in electric field in the BFO film induced by the self-polarization. Our work opens up a new path to utilize TiO2 and may influence the future design of solar cells.

Wu, Fen; Song, Linyu; Guo, Yiping; Jin, Song; Bi, Enbing; Chen, Han; Duan, Huanan; Li, Hua; Liu, Hezhou; Kang, Hongmei

2014-06-01

407

Solution processable titanium dioxide precursor and nanoparticulated ink: application in Dye Sensitized Solar Cells.  

PubMed

Colloidal TiO2 anatase nanoparticles of 4-8 nm diameter capped with 3,6,9-trioxadecanoic acid (TODA) were synthesized at low temperature using water and ethanol as the solvents. ATR-FTIR and (1)H NMR characterization showed the capping acid capability of stabilizing the TiO2 nanoparticles through labile hydrogen bonds. The presence of the capping ligand permitted the further preparation of homogeneous and stable colloidal dispersions of the TiO2 powder in aqueous media. Moreover, after solvent evaporation, the ligand could be easily eliminated by soft treatments, such as UV irradiation or low-temperature thermal annealing. These properties have been used in this work to fabricate mesoporous TiO2 electrodes, which can be applied as photoanodes in Dye Sensitized Solar Cells (DSSCs). For the preparation of the electrodes, the as-synthesized mesoporous TiO2 nanoparticles were mixed with commercial TiO2 (Degussa P25) and deposited on FTO substrates by using the doctor blade technique. A mixture of water and ethanol was used as the solvent. A soft thermal treatment at 140 °C for 2h eliminated the organic compound and produced a sintered mesoporous layer of 6 ?m thickness. The photovoltaic performance of the DSSCs applying these electrodes sensitized with the N3 dye resulted in 5.6% power conversion efficiency. PMID:24326146

Bosch-Jimenez, Pau; Yu, Youhai; Lira-Cantu, Mónica; Domingo, Concepción; Ayllón, José A

2014-02-15

408

Characterization of N3 dye adsorption on TiO2 using quartz-crystal microbalance with dissipation monitoring  

NASA Astrophysics Data System (ADS)

Understanding the kinetics of dye adsorption on semiconductors is crucial for designing dye-sensitized solar cells (DSSCs) with enhanced efficiency. Harms et al. recently applied the Quartz-Crystal Microbalance with Dissipation Monitoring (QCM-D) to study in situ dye adsorption on flat TiO2 surfaces. QCM-D measures adsorption in real time and therefore allows one to determine the kinetics of the process. In this work, we characterize the adsorption of N3, a commercial RuBipy dye, using the native oxide layer of a titanium sensor to simulate the TiO2 substrate of a DSSC. We report equilibrium constants that are in agreement with previous absorbance studies of N3 adsorption, and therefore demonstrate the native oxide layer of a titanium sensor as a valid and readily available planar TiO2 morphology to study dye adsorption.

Wayment-Steele, Hannah K.; Johnson, Lewis E.; Dixon, Matthew C.; Johal, Malkiat S.

2013-09-01

409

Dust in brown dwarfs and extra-solar planets IV. Assessing TiO2 and SiO nucleation for cloud formation modeling  

E-print Network

Clouds form in atmospheres of brown dwarfs and planets. The cloud particle formation processes are similar to the dust formation process studied in circumstellar shells of AGB stars and in Supernovae. Cloud formation modelling in substellar objects requires gravitational settling and element replenishment in addition to element depletion. All processes depend on the local conditions, and a simultaneous treatment is required. We apply new material data in order to assess our cloud formation model results regarding the treatment of the formation of condensation seeds. We re-address the question of the primary nucleation species in view of new (TiO2)_N-cluster data and new SiO vapour pressure data. We apply the density functional theory using the computational chemistry package Gaussian 09 to derive updated thermodynamical data for (TiO2)_N-clusters as input for our TiO2 seed formation model. We test different nucleation treatments and their effect on the overall cloud structure by solving a system of dust momen...

Lee, G; Giles, H; Bromley, S T

2014-01-01

410

Understanding the effect of flower extracts on the photoconducting properties of nanostructured TiO2.  

PubMed

Here we report an easy method to improve the optoelectronic properties of commercially available TiO2 nanopowder using extracts of various flowers viz. Calendula Orange (CO), Calendula Yellow (CY), Dahlia Violet (DV), Dahlia Yellow (DY), Rabbit flower (RF), Sweet Poppy (SP), Sweet Williams (SW) and their Mixed Extracts (ME). Various analysis techniques such as UV-Vis, FTIR, FESEM, XRD, and Raman spectroscopy were used to characterize for elemental, structural and morphological properties of the unmixed/mixed TiO2 nanopowder. TiO2 nanopowder was also calcined at 550 degrees C. Thick films of the these unmixed/mixed powder were printed, using conventional screen printing method, on fluorine doped tin oxide (FTO) substrate with organic binders and dried at 45 degrees C. The photoconducting properties are investigated as a function of wavelength from ultra-violet (UV) to infra-red (IR) region at a constant illumination intensity. Photocurrent gradually decreases when irradiated from UV to IR region. In case of unmixed and uncalcined TiO2, conductance decreased continuously whereas when extracts are added, a flat region of conductance is observed. The overall effect of extracts (colour pigments) is seen as an increase in the photoconductance. Highest photoconductance is observed in case of DY flower extract. Anthocyanins, present in flowers are known to have antioxidative properties and hence can contribute in photoconduction by reducing the surface adsorbed oxygen. This investigation indicates the potential use of flower extracts for dye sensitized solar cell (DSSC). PMID:23421149

Ansari, S G; Bhayana, Laitka; Umar, Ahmad; Al-Hajry, A; Al-Deyab, Salem S; Ansari, Z A

2012-10-01

411

Effects of mesoporous SiO2 , Fe3 O4 , and TiO2 nanoparticles on the biological functions of endothelial cells in vitro.  

PubMed

To comparatively investigate the cytotoxicities of nanomaterials in circulation, in this study, three different types of nanoparticles (NPs; mesoporous SiO2, Fe3O4, and TiO2) with diameters of around 100 nm were synthesized. The morphologies, crystalline phases, and zeta potentials of those NPs were characterized by scanning electron microscopy, X-ray diffraction and zeta potential measurement, respectively. Then, we investigated the influences of different NPs on the biological functions of endothelial cells, in particular of the organelle of cells. The results indicated that different types of NPs had cytotoxic effects in a dose- and time-dependent manner, and there was no significant difference in cytotoxicity between SiO2 and Fe3O4 at concentrations <0.20 mg/mL. The shape and surface charges of NPs greatly affected cellular internalization. We found that cytoskeleton and integrity of cells were destroyed by different NPs. Additionally, the production of reactive oxygen species damaged the mitochondria of cells, in turn leading to cells apoptosis and death. PMID:23776183

Hou, Yanhua; Lai, Min; Chen, Xiuyong; Li, Jinghua; Hu, Yan; Luo, Zhong; Ding, Xingwei; Cai, Kaiyong

2014-06-01

412

The enhanced conductivity and stability of AZO thin films with a TiO2 buffer layer  

NASA Astrophysics Data System (ADS)

Aluminum doped zinc oxide (AZO) films were substitutes of the SnO2:F films on soda lime glass substrate in the amorphous thin-film solar cells due to good properties and low cost. In order to improve properties of AZO films, the TiO2 buffer layer had been introduced. AZO films with and without TiO2 buffer layer were deposited on soda lime glass substrates by r.f. magnetron sputtering. Subsequently, one group samples were annealed in vacuum (0.1 Pa) at 500 °C for 120 s using the RTA system, and the influence of TiO2 thickness on the properties of AZO films had been discussed. The XRD measurement results showed that all the films had a preferentially oriented (0 0 2) peak, and the intensity of (0 0 2) peak had been enhanced for the AZO films with TiO2 buffer layer. The resistivity of TiO2 (3.0 nm)/AZO double-layer film is 4.76×10-4 ? cm with the maximum figure merit of 1.92×10-2 ?-1, and the resistivity has a remarkable 28.7% decrease comparing with that of the single AZO film. The carrier scattering mechanism of TiO2 (3.0 nm)/AZO double-layer film had been described by Hall measurement in different temperatures. The average transmittance of all the films exceeded 92% in the visible spectrum. Another group samples were heat treated in the quartz tube in air atmosphere, and the effect of TiO2 thickness on thermal stability of AZO films had been discussed.

Yang, Tianlin; Song, Shumei; Li, Yanhui; Xin, Yanqing; Du, Guiqiang; Lv, Maoshui; Han, Shenghao

2012-12-01

413

Quantum-Tuned Multijunction Solar Cells  

NASA Astrophysics Data System (ADS)

Multijunction solar cells made from a combination of CQDs of differing sizes and thus bandgaps are a promising means by which to increase the energy harvested from the Sun's broad spectrum. In this dissertation, we first report the systematic engineering of 1.6 eV PbS CQD solar cells, optimal as the front cell responsible for visible wavelength harvesting in tandem photovoltaics. We rationally optimize each of the device's collecting electrodes---the heterointerface with electron accepting TiO2 and the deep-work-function hole-collecting MoO3 for ohmic contact---for maximum efficiency. Room-temperature processing enables flexible substrates, and permits tandem solar cells that integrate a small-bandgap back cell atop a low thermal-budget larger-bandgap front cell. We report an electrode strategy that enables a depleted heterojunction CQD PV device to be fabricated entirely at room temperature. We develop a two-layer donor-supply electrode (DSE) in which a highly doped, shallow work function layer supplies a high density of free electrons to an ultrathin TiO2 layer via charge-transfer doping. Using the DSE we build all-room-temperature-processed small-bandgap (1 eV) colloidal quantum dot solar cells suitable for use as the back junction in tandem solar cells. We further report in this work the first efficient CQD tandem solar cells. We use a graded recombination layer (GRL) to provide a progression of work functions from the hole-accepting electrode in the bottom cell to the electron-accepting electrode in the top cell. The recombination layers must allow the hole current from one cell to recombine, with high efficiency and low voltage loss, with the electron current from the next cell. We conclude our dissertation by presenting the generalized conditions for design of efficient graded recombination layer solar devices. We demonstrate a family of new GRL designs experimentally and highlight the benefits of the progression of dopings and work functions in the interlayers.

Koleilat, Ghada I.

414

Mesoporous perovskite solar cells: material composition, charge-carrier dynamics, and device characteristics.  

PubMed

We report on our investigations on charge transport and recombination in TiO2-based mesoporous solar cells using PbI2 and various perovskite compositions, including CH3NH3PbI3, CH3NH3PbI2Br, CH3NH3PbIBr2, and CH3NH3PbBr3. The mesoporous TiO2 film is about 650 nm thick. Electron microscopy measurements show that no perovskite capping layer is formed on the top surface of the TiO2 film. Intensity-modulated photocurrent/photovoltage spectroscopies show that the electron diffusion coefficient and recombination lifetime are governed by the underlying mesoporous TiO2 film and thus do not depend on the perovskite composition. However, replacing the perovskite absorber with PbI2 leads to a diffusion coefficient that is about a factor of 5 slower than that in perovskite-based devices. We also find that TiCl4 treatment of the mesoporous TiO2 film prior to device fabrication substantially reduces the charge recombination kinetics in mesoporous perovskite solar cells. PMID:25407110

Zhao, Yixin; Nardes, Alexandre M; Zhu, Kai

2014-11-19

415

Transparent, well-aligned TiO(2) nanotube arrays with controllable dimensions on glass substrates for photocatalytic applications.  

PubMed

Transparent, well-aligned TiO(2) nanotube arrays (NTAs) with controllable dimensions are grown on glass substrates via atomic layer deposition (ALD) of TiO(2) onto free-standing porous anodic alumina (PAA) templates. Photodegradation of aqueous methylene blue (MB) solution and solid stearic acid (SA) film using TiO(2) NTAs of various wall thicknesses are investigated. The Pd functionalized TiO(2) NTAs, with a wall thickness of 15 nm and height of 200 nm, has the highest photodegradation efficiency at 76% after 4 h of UV irradiation. These functionalized NTAs are able to photodegrade MB molecules completely as no obvious demethylated byproducts are observed during the process. It also demonstrates excellent photocatalytic activity for solid contaminants such as SA film. By using the ALD technique, the nanotube wall thickness can be precisely controlled so that it is sufficiently thin to be transparent while sufficiently thick for excellent photocatalytic performances. The transparent TiO(2) NTAs on glass substrates with excellent photocatalytic properties might have potential applications in self-cleaning coating, transparent electronics, and solar cells. PMID:20356197

Tan, Lee Kheng; Kumar, Manippady K; An, Wen Wen; Gao, Han

2010-02-01

416

Large scale synthesis and gas-sensing properties of anatase TiO2 three-dimensional hierarchical nanostructures.  

PubMed

Three-dimensional (3D) crystalline anatase titanium dioxide (TiO(2)) hierarchical nanostructures were synthesized through a facile and controlled hydrothermal and after-annealing process. The formation mechanism for the anatase TiO(2) 3D hierarchical nanostructures was investigated in detail. The 3D hierarchical nanostructures morphologies are formed by self-organization of several tens of radially distributed thin petals with a thickness of several nanometers with a larger surface area. The surface area of TiO(2) hierarchical nanostructures determined by the Brunauer-Emmett-Teller (BET) adsorption isotherms was measured to be 64.8 m(2) g(-1). Gas sensing properties based on the hierarchical nanostructures were investigated. A systematic study on sensitivity as a function of temperatures and gas concentrations was carried out. It reveals an improved ethanol gas sensing response property with a sensitivity of about 6.4 at 350 degrees C upon exposure to 100 ppm ethanol vapor for the TiO(2) hierarchical nanostructures. A gas sensing mechanism based on the adsorption-desorption of oxygen on the surface of TiO(2) is discussed and analyzed. This novel gas sensor can be multifunctional and promising for practical applications. Furthermore, the hierarchical nanostructures with high surface area can find variety of potential applications such as solar cells, biosensors, catalysts, etc. PMID:20597492

Wang, Chengxiang; Yin, Longwei; Zhang, Luyuan; Qi, Yongxin; Lun, Ning; Liu, Ningning

2010-08-01

417

Biological construction of single-walled carbon nanotube electron transfer pathways in dye-sensitized solar cells.  

PubMed

We designed and mass-produced a versatile protein supramolecule that can be used to manufacture a highly efficient dye-sensitized solar cell (DSSC). Twelve single-walled carbon-nanotube (SWNT)-binding and titanium-mineralizing peptides were genetically integrated on a cage-shaped dodecamer protein (CDT1). A process involving simple mixing of highly conductive SWNTs with CDT1 followed by TiO2 biomineralization produces a high surface-area/weight TiO2 -(anatase)-coated intact SWNT nanocomposite under environmentally friendly conditions. A DSSC with a TiO2 photoelectrode containing 0.2?wt?% of the SWNT-TiO2 nanocomposite shows a current density improvement by 80% and a doubling of the photoelectric conversion efficiency. The SWNT-TiO2 nanocomposite transfers photon-generated electrons from dye molecules adsorbed on the TiO2 to the anode electrode swiftly. PMID:25111295

Inoue, Ippei; Watanabe, Kiyoshi; Yamauchi, Hirofumi; Ishikawa, Yasuaki; Yasueda, Hisashi; Uraoka, Yukiharu; Yamashita, Ichiro

2014-10-01

418

Highly efficient photon-to-electron conversion with mercurochrome-sensitized nanoporous oxide semiconductor solar cells  

Microsoft Academic Search

Dye-sensitized solar cells based on nanoporous oxide semiconductor thin films such as TiO2, Nb2O5, ZnO, SnO2, and In2O3 with mercurochrome as the sensitizer were investigated. Photovoltaic performance of the solar cell depended remarkably on the semiconductor materials. Mercurochrome can convert visible light in the range of 400–600nm to electrons. A high incident photon-to-current efficiency (IPCE), 69%, was obtained at 510nm

Kohjiro Hara; Takaro Horiguchi; Tohru Kinoshita; Kazuhiro Sayama; Hideki Sugihara; Hironori Arakawa

2000-01-01

419

Photocatalytic TiO2 nanoparticles enhanced polymer antimicrobial coating  

NASA Astrophysics Data System (ADS)

Copper (Cu) containing coatings can provide sustainable protection against microbial contamination. However, metallic Cu coatings have not been widely used due to the relatively high cost, poor corrosion resistance, and low compatibility with non-metal substrates. Titanium dioxide (TiO2) possesses antibacterial functions by its photocatalytic properties which can destroy bacteria or suppress their reproduction. TiO2 also has the function of improving the mechanical properties through particle dispersion strengthening. We have recently developed an innovative polymer based coating system containing fine particles of Cu and TiO2 nanoparticles. These polymer based coatings simultaneously display excellent antimicrobial and good mechanical properties. The results showed that the addition of TiO2 has improved the antimicrobial property under sunlight, which provides extended applications in outdoor environment. The elimination of 106 bacterial by contacting the coatings without TiO2 needs 5 h, while contacting with the Cu/TiO2- 1 wt.% TiO2 took only 2 h to kill the same amount of bacteria. The coatings also presented enhanced hardness and wear resistance after adding TiO2. The width of wear track decreased from 270 ?m of the Cu-polymer coating to 206 ?m of Cu/TiO2-polymer coatings with 10 wt.% TiO2. Synchrotron Infrared Microscopy was used to in-situ and in-vivo study the bacteria killing process at the molecular level. The real-time chemical images of bacterial activities showed that the bacterial cell membranes were damaged by the Cu and TiO2 containing coatings

Wei, Xiaojin; Yang, Zhendi; Tay, See Leng; Gao, Wei

2014-01-01

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Laser-Sintered $\\\\hbox{TiO}_{2}$ Films for Dye Solar Cell Fabrication: An Electrical, Morphological, and Electron Lifetime Investigation  

Microsoft Academic Search

We have carried out a systematic and combined I-V , electrochemical impedance spectroscopy (EIS), and scan- ning emission microscopy (SEM) investigation of dye solar cells (DSCs) fabricated with laser-sintered TiO2 photoanodes as a function of laser-integrated fluence ?. We show that the electron lifetime ?oc in the TiO2 film extracted from EIS spectra monoton- ically increases with laser sintering fluence

Girolamo Mincuzzi; Luigi Vesce; Massimiliano Liberatore; Andrea Reale; Aldo Di Carlo; Thomas M. Brown

2011-01-01