Fabrication And Properties Of TiO₂/PW₁₂ Composite Films Dye-sensitized Solar Cells

Abstract:Dye-sensitized solar cells (DSSCs) have drawn great attention in scientific researches and practical applications for the excellent photoelectric conversion efficiency and low cost, but titanium dioxide (TiO2) nanocrystalline particles displays disorderly, which leads to slow electron transfer. In order to improve the electron transport properties of TiO2nanocrystalline thin films and photovoltaic efficiency and avoid the use of expensive ruthenium complex dyes, in this thesis the performance of dye-sensitized solar cells were studied based on TiO2composite films prepared by a two-step method sensitived by D102dye.1. PW12-TiO2powder was prepared by impregnation, then PW12-TiO2and TiO2were mixed with the solvent, a dispersant, a binder and a pore-forming agent to prepare a slurry. PW12/TiO2films were obtained by doctor blade method, of which the morphology, structure, optical absorption properties and performance of D102dye-sensitized solar cells were studied by means of field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), electrochemical analysis. Results have shown that PW12-TiO2powder is20nm TiO2particles anatase-based with Keggin type phosphotungstic acid structure remaining. The introduction of phosphotungstic acid does not alter the morphology and structure of PW12/TiO2films prepared by two-step method. PW12in the PW12/TiO2films as a electron acceptor promotes the separation of electrons and holes and reduces the resistance of electron transport in the film, thus improving the photoelectric conversion efficiency of the cell. Open circuit voltage of DSSCs remaines unchanged. The short-circuit current density of DSSCs has improved greatly with the maximum short-circuit current density JSC=9.52mA cm-2and the maximum total energy conversion efficiency η=3.5%increasing by66%and75%than the pure TiO2under the same conditions, respectively.2. WO3-TiO2powder was prepared by surface modification. PW12-TiO2, WO3-TiO2and TiO2powder were mixed with the solvent, a dispersant, a binder and a pore-forming agent to prepare a slurry, then PW12/WO3/TiO2films were obtained by doctor blade method, and then the morphology and structure, optical absorption properties and performance of DSSCs were researched. Results have shown that PW12-TiO2and WO3-TiO2together in the PW12/WO3/TiO2films reduce electron-hole recombination and resistance in electron transport, thus improving the efficiency of electron injection and electron collection efficiency. The performance of DSSC based on PW12/WO3/TiO2is better than TiO2films with maximum battery short-circuit current density increasing by about1.3times than that of pure TiO2, and the highest photoelectric conversion efficiency reaches to5.0%, which increased1.5fold than pure TiO2under the same conditions. There are27figures,8tables and93references in this paper.