TiO2 Microspheres with Controllable Surface Area and Porosity for Enhanced Light Harvesting and Electrolyte Diffusion in Dye-Sensitized Solar Cells

摘要

An optimized configuration of TiO2 microspheres in photoanodes is of great importance to prepare highly efficient dye-sensitized solar cells (DSSCs). In this work, TiO2 microspheres with tunable diameter, pore size, and porosity are synthesized by subtly adjusting the synthesizing conditions, including ratios of deionized water, ammonia, and ethanol, respectively. TiO2 microspheres are obtained with large pore sizes and a high porosity without sacrificing specific surface areas. In addition, the effect of their porosity and pore size on the performance of DSSCs is investigated. As confirmed by the dye-loading ability and electrolyte diffusion resistance, the large mesopores and the high porosity of the TiO2 microspheres can improve dye adsorption and facilitate electrolyte diffusion, giving rise to a high light-harvesting and electron collection efficiency. Consequently, the highest photocurrent of 19.21 mA cm(-2) and a power conversion efficiency of 9.98% are obtained by using the TiO2 microspheres with the highest porosity, compared with a 9.29% efficiency demonstrated by the lowest porosity (an improvement of 7.4%). By modifying the interconnection and the external pores of the microspheres photoanode, a high efficiency of 11.67% is achieved for a DSSC based on the most potent TiO2 microspheres.