An ionic compensation strategy for highperformance mesoporous perovskite solar cells: healing defects with tri- iodide ions in a solvent vapor annealing process

In this paper, tri-iodide ions [I-3(-)] are introduced to heal ionic point defects through ionic compensation of charged point defects during the annealing process. The ionic compensation strategy presented here significantly improves the quality of CH3NH3PbI3 films, as well as reducing the non-radiative recombination sites and prolonging the carrier lifetime. The best PCE of the device fabricated by this strategy is 18.53%, which is an improvement of around 30% compared to that of the pristine device (14.16%). Simultaneously, the improved device exhibits small hysteresis and excellent stability. Moreover, we envision that the ionic compensation strategy based on halide ions can be generalized to other organic-inorganic halide perovskite materials such as CH3NH3PbBr3, CH3(NH2)(2)PbI3, CsPbI3 and their mixtures.