Abstract

Improvement of the photoconversion efficiency and operational stability under environmental conditions is a principal challenge confronted to move forward toward commercialization of dye-sensitized solar cell (DSSC) devices the world over. Herein, enhancement of sunlight harvesting by increasing light scattering via embedding mesoporous TiO2 beads in a photoanode matrix and delaying electrolyte leakage using gel polymer electrolyte, regarded as two approaches to address this challenge, respectively. Photoanodes with various thicknesses and architectures of mesoporous TiO2 beads and nanoparticles are employed in the assembly of DSSC devices in the presence of gel polymer electrolyte. Optical and microstructural analysis showed submicron spherical beads with suitable monodispersity consisting of pure anatase TiO2 nanocrystals and very fine pores. Compared to TiO2 nanoparticles, such a 3D hierarchical structure showed a higher specific surface area (85 m(2) g(-1)) and sunlight scattering (similar to 20%) but a lower amount of dye-sensitizer adsorption. The photovoltaic characteristics of the assembled devices with various architectures of photoanodes were recorded under simulated AM 1.5 sunlight. The highest photoconversion efficiency of 9.8% was achieved for the photoanode based on mesoporous TiO2 beads in the presence of gel polymer electrolyte, which was comparable to that in liquid electrolyte. Furthermore, it showed a longer operational stability under realistic ambient conditions.