Well-Organized Mesoporous TiO2 Photoelectrodes by Block Copolymer-Induced Sol-Gel Assembly for Inorganic-Organic Hybrid Perovskite Solar Cells

Abstract

A well-aligned mesoporous thin layer was formed by spin-coating followed by the burn-out of its organic components at 500 degrees C. This film, prepared by an inorganic sol gel process using block copolymers as a sacrificial template, showed mesoporous (mp) and crack-free layers with various pore sizes depending on the amount of 1,3,5-trimethylbenzene (TMB), which acted as a swelling agent. The mesoporous photoanodes were used in the fabrication of CH3NH3Pb(I0.9Br0.1)(3) perovskite-based solar cells. The cells showed overall power conversion efficiencies of 11.7% and 12.8% with the 10 and 15 nm mp-layers, respectively. The superior performance shown in the 15 nm mp-layers may be attributed to the easier filling of CH3NH3Pb(I0.9Br0.1)(3) by bigger pore sizes, and the efficiency is comparable with that of the reference cell fabricated by TiO2 paste. This template-induced self-organizing sol-gel process was shown to be a useful technique for depositing mesoporous photoanodes in the fabrication of perovskite-based solar cells