Enhanced performance of TiO2-based perovskite solar cells with Ru-doped TiO2 electron transport layer

Perovskite solar cells (PSCs) as the most promising alternative to the Si solar cells have been developed rapidly in recent time. Superior electron mobility and conductivity of the compact layer material are necessary for high efficiency in perovskite solar cells by reducing excessive charge accumulation and guaranteeing effective electron injection at the compact layer/perovskite interface. In this study, Ru ions were introduced into traditional compact TiO2 to improve the electron transporting layer (ETL) properties and conductivity performance. Ru4+ was discovered in the Ru:TiO2 according to the result of XPS. The reduced trap-filled limit voltage (VTFL) of the Ru:TiO2 compact layers showed that trap density in the Ru:TiO2 film was lower than that of the pristine TiO2 film. The PSCs based on 1 mol% Ru:TiO2 exhibited the suitable band gap, low resistivity and high carrier density, comparing with the undoped compact TiO2, the charge transportation at the compact layer/mesoporous layer interface was enhanced with the incorporation of Ru, resulting in the reduction in hysteresis of the device. The power conversion efficiency (PCE) of the Ru-doped compact TiO2 film based PSCs was improved from 14.83% to 18.35%.