Supercritical fluid processing of mesoporous crystalline TiO2 thin films for highly efficient dye-sensitized solar cells

Abstract

In this study, a high light-to-electricity conversion efficiency of 5.14% was achieved by applying a TiO₂ thin film with a thickness of 1.87 µm as an electrode material under an AM 1.5 solar light (100 mW cm⁻²). This high efficiency can be attributed to post-treatment by the supercritical fluid process and the addition of nanoparticles to the thin film. Supercritical fluid treatment is shown to significantly enhance the thermal stability of these thin films. Thus, the high porosity of the treated films was maintained even upon calcination at a high temperature. Additionally, the addition of crystalline light scattering nanoparticles in the thin film not only increases the crystallinity of the thin films but also ensures capture of the incident light and increases the efficiency of light harvesting. The thin film with well-preserved mesopores among the nanoparticles can capture the incident light efficiently and further increase efficiency of light harvesting, which leads to the remarkably high light-to-electricity conversion efficiency.