Modulations of various alkali metal cations on organometal halide perovskites and their influence on photovoltaic performance

Both the barrier at the perovskite/TiO2 interface and the defect in perovskite play a crucial role in I-V hysteresis. The incorporation of K+ into perovskite not only results in the elimination of the barrier but also causes the reduction of the defect. Consequently, the solar cell with a high efficiency of over 20% and negligible hysteresis is achieved based on K+ doped perovskite.221