Enhancing the Stability of Perovskite Solar Cells through an Iodine Confining Strategy

One big challenge limiting the stability of perovskite solar cells (PSCs) is that iodine species produced in perovskite tend to diffuse and escape from PSCs, accelerating perovskite decomposition and destroying other functional layers as well. Motivated by the idea of iodine confinement in lithium–iodine batteries, here an iodine confining strategy is proposed to fabricate stable PSCs by incorporating poly(2-vinylpyridine) (P2VP) into the perovskite film. P2VP can effectively bond with the iodine product from perovskite decomposition to inhibit its diffusion and volatilization from PSCs, thus suppressing perovskite decomposition and device degradation. The resulting devices show an efficiency of 22.97% with good stability in inverted PSCs, retaining 90.9% of the initial efficiency after 85 °C for 750 h. In addition, operational stability is also greatly improved, and 90.0% of its initial efficiency is retained after MPP tracking for 1000 h.