Research On The Fabrication Of Photoelectrode With {001}Facets Exposed TiO₂Nanosheet-based Hierarchical Spheres As Scattering Layer By Electrophoresis Deposition

Dye sensitized solar cell (DSSC) has attracted a world-wide attention because of its relative high power conversion efficiency, easy fabrication, low cost and environmental friendly. At present it is still necessary to improve the DSSC’s performance on power conversion efficiency and long-term stability. A typical DSSC consists of the following four parts:photoelectrode, dyes, electrolyte and counter electrode. Among these photoelectrode is the most important section. It has been widely proved that introducing a scattering layer can effectively improve the cell efficiency. Meanwhile, the characteristics of good scattering ability and an expected high dye adsorption ability for{001} exposed nanosheet-based TiO2hierarchical spheres made them ideal candidate for scatters in DSSC. On the other hand, electrophoresis deposition shows superiority in preparing scattering layer:its mild fabrication method can effectively preserve the microstructure of scatters. In this paper, we focused on the DSSC’s photoelectrode materiel, fabrication method of photoelectrode and microstructure of photoelectrode. We study these three factors’impact on the power conversion efficiency of DSSC.1. A hydrothermal method of synthesize anatase TiO2nanocrystalline has been explored. The product we get has a average size of20nm and shows a20%increase on power conversion efficiency than the commonly used P25.2. Two methods of fabrication the DSSC photoelectrode:electrophoresis deposition and paste coating have been compared for the reproductivity and power conversion efficiency. We found that both of these method showed good reproductivity and reliability, but the film fabricated by electrophoresis deposition was more compact and showed a better electron-conducting ability, therefore a higher power conversion efficiency.3.Through a facile solvothermal method,{001} exposed nanosheet-based TiO2hierarchical spheres with an average size of1μm have been abtained. We introduced these spheres into DSSC by using them as scattering layer in a bilayered photoelectrode ({001} exposed TiO2hierarchical spheres deposited on common TiO2nanoparticles) through electrophoresis deposition.These bilayed photoelectrode showed a26%increase on power conversion efficiency than single layered DSSC photoelectrode composed of common TiO2nanoparticles. By optimizing the film thickness, we get a power conversion efficiency as high as7.66%. We also discussed the reason for the efficiency enhancement through the dye adsorption and light harvesting ability.