Improved Quantum Efficiency of Highly Efficient Perovskite BaSnO3-Based Dye-Sensitized Solar Cells

Abstract

Ternary oxides are potential candidates as an electron-transporting material that can replace TiO2 in dye-sensitized solar cells (DSSCs), as their electronic/optical properties can be easily controlled by manipulating the composition and/or by doping. Here, we report a new highly efficient DSSC using perovskite BaSnO3 (BSO) nanoparticles. In addition, the effects of a TiCl4 treatment on the physical, chemical, and photovoltaic properties of the BSO-based DSSCs are investigated. The TiCl4 treatment was found to form an ultrathin TiO2 layer on the BSO surface, the thickness of which increases with the treatment time. The formation of the TiO2 shell layer improved the charge-collection efficiency by enhancing the charge transport and suppressing the charge recombination. It was also found that the TiCl4 treatment significantly reduces the amount of surface OH species, resulting in reduced dye adsorption and reduced light-harvesting efficiency. The trade-off effect between the charge-collection and light-harvesting efficiencies resulted in the highest quantum efficiency (i.e., short-circuit photocurrent density), leading to the highest conversion efficiency of 5.5% after a TiCl4 treatment of 3 mm (cf. 43% for bare BSO). The conversion efficiency could be increased further to 6.2% by increasing the thickness of the BSO film, which is one of the highest efficiencies from non-TiO2-based DSSCs.