Preparation Of Titanium Dioxide Photoanode By Electrophoretic Deposition And Its Application In Dye Sensitized Solar Cells

Dye-sensitized solar cell?DSSC?is a kind of clean,high theoretical photoelectric conversion efficiency and simple preparation of solar cells,and has potential application prospects.In recent years,a large number of researchers have paid attention to it.As an important part of DSSC,a photoanode plays the role of dye absorption and electronic transmission,showing great influence on the photoelectric conversion efficiency of a DSSC.A traditional photoanode is usually composed of nano-TiO₂,which has small particle size,causing serious surface recombination.In order to improve device performance and promote the commercialization of dye-sensitized solar cells,it is necessary to further control the morphology and interface of the photoanode.In this work,TiO₂photoanodes were prepared by simple electrophoretic deposition method.The morphology of the photoanodes was regulated,the interface was modified and the structure was optimized to improve the performance of the devices.The mechanism for the performance enhancement was also studied.Specific research works are as follows:?1?Surface treatment of FTO substrate and porous TiO₂ film can reduce the recombination of photogenerated carriers and improve the charge collection efficiency of the photoanode.Using tetrabutyl titanate as precursor solution,a compact layer of TiO₂ was prepared on FTO substrates by a spin-coating-calcination method.Then,the mesoporous layer of titanium dioxide was deposited on modified FTO substrates by an electrophoretic deposition method.Finally,dihydroxy bis?ammonium lactate?titanium solution was dropped onto the surface of the film and calcined to complete the preparation of the final TiO₂ photoanode.The results show that the compact layer of TiO₂ can reduce the cracks on the surface of TiO₂ photoanode,prevent the contact between FTO and electrolyte,and suppress the back recombination between electrons in FTO and electrolyte.The surface treatment of TiO₂ film can further reduce the cracks on the surface of the film,enhance the connection among TiO₂ particles,reduce the charge recombination in thin films,and improve the charge transfer efficiency of the photoanode.The final photoelectric conversion efficiency of the DSSC increases from 6.46%to 8.47%.?2?The effect of applied voltage on the performance of electrodeposited TiO₂ photocathode and device was studied.The higher the voltage is applied,the faster the nanoparticles deposition rate and the thicker the film thickness are,thus adsorbing more dyes.However,the films prepared under high voltage conditions often show cracks,the surface of the films is not uniform,and the charge transfer performance is poor.In order to fabricate an efficient photoanode,a low-voltage-high-voltage deposition method was employed.Finally,a thin film of TiO₂ with enough thickness and good morphology was prepared,and the photoelectric conversion efficiency of the device without surface treatment was increased to 7.77%.?3?Low temperature preparation and device performance study of TiO₂/graphene composite photoanodes.TiO₂/graphene composite films were deposited by an electrophoretic deposition and then prepared by low temperature pressing.The composite photoanodes were applied to DSSC devices.The results show that the low-temperature pressing can improve the morphology of the films and promote the connection between TiO₂ particles.In,addition,the introduction of graphene can further improve the charge transfer performance of the photoelectrodes,thereby improve the photoelectric conversion efficiency of DSSC devices.