Mg-doped TiO2 boosts the efficiency of planar perovskite solar cells to exceed 19%

Mg as an effective ion dopant has been introduced into compact TiO2 ETL for planar perovskite solar cells. It is found that Mg doping can shift the Fermi energy level of the ETL upward and decrease the resistivity of the TiO2 film. Carrier transport velocity is thus enhanced and high charge collection efficiency has been achieved at high bias voltages, leading to a higher fill factor (FF) and better cell efficiency. More than 19% power conversion efficiency has been obtained.