Efficient planar heterojunction perovskite solar cells with Li-doped compact TiO2 layer

Perovskite solar cells (PSCs) have been developed rapidly in recent time, and efficient planar PSCs are regarded as the most promising alternative to the Si solar cells. In this study, we demonstrated that Li-doping of compact TiO2 can reduce the density of electron traps and increase the conductivity of the electron transport layer (ETL) of PSCs. Due to the improved electronic property of ETL, the Li-doped compact TiO2 based planar heterojunction PSCs exhibit negligible hysteretic J-V behavior. Comparing with the undoped compact TiO2 based PSCs, the power conversion efficiency (PCE) of the Li-doped compact TiO2 film based PSCs is improved from 14.2% to 17.1%. Fabrication of highly efficient planar PSCs provides a pathway for commercialization of PSCs.