Efficient quasi-solid-state dye-sensitized solar cells aided by mesoporous TiO2 beads and a non-volatile gel polymer electrolyte

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 m² g⁻¹) and sunlight scattering (∼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.