Dye-sensitized TiO2 Thin Film Research Articles

Development of dye sensitized TiO2 thin films for efficient energy harvesting

In the present investigation, we are reporting development of 3D nanoflower like architecture of TiO2 for dye sensitized solar cell (DSSC). Initially, TiO2 thin films were synthesized by using a simple hydrothermal approach. The effect of deposition time on the optostructural, morphological, compositional and photoelectrochemical properties of TiO2 thin films was studied. The optical study reveals direct and allowed transition with band gap variation in the range of 2.4–3.0 eV. The XRD pattern confirms rutile tetragonal crystal structure with crystallite size ranging from 20 to 50 nm. The morphological analysis shows presence of 1D nanorods assembling to give a 3D nanoflower like architecture. The compositional data confirms the presence of titanium and oxygen in the 1:2 with respective oxidation state. HRTEM images are in good agreement with SEM images confirming single crystalline nature of TiO2 thin films. As deposited TiO2 thin films are sensitized with different concentrations of Betanin dye. This natural dye sensitized TiO2 is used as photoelectrode to determine the photovoltaic performance. The purity and structure of betanin dye was determined by LC-MS and FT-IR. The PEC performance increases from 5.82% to 14.21% with increase in deposition time. Further in order to study the charge transport mechanism EIS is done. The stability study of T-9 sample is done to confirm the stability.

Alkanna tinctoria barks as organic photo sensitizers for dye sensitized TiO2 thin film solar cells.

Alkanna tinctoria barks as organic photo sensitizers for dye sensitized TiO2 thin film solar cells.

Ionic Liquid-Induced Local Charge Compensation: Effects on Back Electron-Transfer Rates in Dye-Sensitized TiO2 Thin Films

The effect of ionic liquid electrolytes on back electron-transfer rates for dye-sensitized TiO2 thin films was investigated using microsecond–millisecond transient absorption. For D35/TiO2 and [Ru(dcb)3]2+/TiO2 in electrolytes based on 1-alkyl-3-methyl-imidazolium hexafluorophosphate, significantly slower back electron-transfer rates, compared to those observed in neat acetonitrile (CH3CN) and LiClO4/CH3CN, were found. Surprisingly, no such trends were observed for N3/TiO2 under the same conditions. This inconsistency points to the need for mechanistic understanding of how the structure and properties of dyes affect the electrolyte–dye interface interactions in ionic liquid (IL)-based dye-sensitized solar cells (DSSCs). To explain the observed behavior we propose an electrostatic effect at the TiO2–electrolyte interface, where the bulky IL cations rearrange at the TiO2 surface, locally compensating the charge. This would be consistent with N3 behaving differently because of its negatively charged SCN– lig...

EFFECT OF USING PITAYA PEEL AS DYE-SENSITIZER AND DYE MOLECULES IN ELECTROLYTE FOR PHOTOELECTROCHEMICAL REACTION

Natural dye sensitizer in photoelectrochemical shows a great potential in improving the efficiency of metal oxide semiconductor especially Titanium dioxide (TiO2) due to its prominent in absorbing visible light and also low cost. In this work, the effect of using pitaya peel as natural dye sensitizes to TiO2 has been studied through characterizations analysis and PEC test. The bare TiO2 thin films were fabricated on Fluorine-doped tin oxide (FTO) glass substrate by doctor blade method meanwhile dyesensitized TiO2 thin films prepared by immersion of TiO2 in the dye extracts. The fabricated thin films were characterized with Scanning Electron Microscopy (SEM), X-ray difractometer (XRD), UV-Vis spectrophotometer and photoelectrochemical analysis. The surface of TiO2 was porous and uniform meanwhile dye particles could not been observed due to very small size. The energy band gap of dye-sensitized TiO2 from the UV-Vis spectrum is 2.1 eV which is smaller than bare TiO2 (3.7 eV). Meanwhile, photoactivities of dye-sensitized TiO2 has the highest compared to bare TiO2 photoelectrodes which is 127μA/cm 2 in 6.25% v/v of pitaya dye in the electrolyte.

Dye-Sensitized Solar Cells Assembled with Modified Photoanode and Carbon Nanotubes as Counter Electrode

A dye-sensitized TiO2 thin film photoanode and carbon-based counter elctrode were fabricated on the FTO substrate with doctor-blade method. And we have coated the ZnO nanoparticles successfully on the TiO2 photoanode through a simple dipping treatment. The photoelectric performance of the assembled cells was investigated by absorption spectra and current-voltage characteristics (I-V curves). Results show that the absorbance of ZnO/TiO2 composite photoanode increases 5.4% compared to pure TiO2 photoanode. The optimal photoelectronic property can be reached when dipping time is 2h in Zn (CH3COO)2 solution. And at this point, the photoelectric conversion efficiency increases up to 50%. The enhancement mechanism has been discussed in detail.

Photosensitization of Dye/TiO<sub>2</sub> Thin Films by Using Natural Dye of TCPP

The Dye-Sensitized TiO2 thin film fabricated by TiO2 nanoparticles is a novel technology with advantage in low cost, little pollution and simple in manufacturing process. The fiber-shaped reacting sites provide enlarged photo-sensing area of the TiO2 thin films. Natural dye of TCPP was applied to improve the photo absorbability in this study. Besides, a novel plasma surface activation technique employed on the thin film showed well performance compared with previous reports by heating methods. The SEM images demonstrate that the nano-TiO2 composites deposited on the fiber substrate. Degradation of acetone under 365 and 420 nm light irradiation were conducted to evaluate the photocatalytic ability of the TiO2 and TCPP/TiO2 thin films. While TiO2 thin films gel catalyst showed good photocatalytic performance with a high degradation efficiency of 99.9%, only about 80% conversion efficiency was achieved by the TCPP/TiO2 thin films reactor under 365 nm light irradiation. Although the TCPP dye on TiO2 nanoparticle shows beneficial reflection intensity in 420 nm, the acetone degradation capability of TiO2 and TCPP/ TiO2 thin films reactor decreased about 30% and 25% respectively compared with the degradation efficiency under 365 nm.

Photo-induced degradation of Ru(II) complex absorbed on anatase TiO2 thin film electrode

Photo-induced degradation of a monolayer of Ru(II) complex absorbed on anatase TiO2 thin film was studied by using resonant micro-Raman spectroscopy. Under intense light radiation of a laser and in the absence of a reducing agent, the dye decomposed quickly. When the dye-sensitized TiO2 thin film electrode was covered by a reducing agent, namely the I−/I 3 − redox couple, the photo-induced decomposing rate was slowed by a factor of ∼106. In both cases, the dye decomposed with time under an exponential law.

Sensitizing Mechanism and Adsorption Properties of Dye-Sensitized TiO2 Thin Films

The dye-sensitized TiO2 complex films were prepared by the dye coat onto TiO2 surfaces, and the sensitizing mechanism and adsorption properties of the dye-sensitized TiO2 complex films were investigated. The influence of the application conditions of dye adsorbed on TiO2 films on the amount of dye adsorption was discussed. Experimental results show that the concentration, the temperature of dye solutions and the dipping time of TiO2 films in the dye solutions have a significant influence on the amount of dye adsorption. Cell test indicates that the conversion efficiency of light to electricity increases with the amount of dye adsorption.

Stability of Anthocyanin Sensitized TiO2 Photoelectrochemical (PEC) Solar Cells Prepared by Sol Gel Process

Highly porous dye sensitized TiO2 thin film solar cells have been prepared by the sol gel process. Sensitization was achieved by use of anthocyanin pigment extracted from delphinidin purple and cyanidin 3-5 diglucose (C35D). Sensitization was also studied on ruthenium complex RuL* sensitization dye. Dye sensitized photoelectrodes have exhibited broad transmission minimum in the visible range. Solar cells fabricated from these electrodes gave overall conversion efficiencies of 3.16% for delphinidin purple and 2.97% for C35D. RuL dye sensitized solar cell gave 4.84%. The cells\' stability performance in terms of photovoltage was found to drop with time of exposure. However the cells still exhibited I-V characteristics over a long period (six months) of study. *L = bis (isthiocyanato) ruthenium (II)-bis-2,2-bipyridine-4,4\'-dicarboxylic ligand (Af. J. of Science and Technology: 2002 3(2): 56-61)