Defect Passivation in Halide Perovskite Films by p-Methoxy Phenylacetonitrile for Improved Solar Cell Efficiency and Stability

The certification efficiency of halide perovskite solar cell is as high as 25.7%, which is one of the most efficient solar cells at present. However, the defects in the halide perovskite including grain boundary, interface defects and ionic defects often act as nonradiative composite sites, which lead to rapid degradation of halide perovskite films, deteriorate the performance of perovskite devices and lead to instability. In this work, a suitable multifunctional molecule additive p-Methoxy Phenylacetonitrile (pMP) is selected to improve the film and device stability. Specifically, pMP delays the crystallization rate of halide perovskite and promotes the formation of high-quality large grain halide perovskite films, and C ≡ N in pMP forms a coordination bond with Pb 2+ and passivates the uncoordinated Pb 2+ defects. Moreover, the π bonds increase electrons transport. In addition, the methoxy group in pMP forms an effective barrier on halide perovskite to enhance its water stability. With influence of the comprehensive effect of these factors of pMP, the PSC with pMP additive achieved the highest efficiency of 21.26%, and significantly improved the stability of moisture resistance.