Dual-Resistance of Ion Migration and Moisture Erosion via Hydrolytic Crosslinking of Siloxane Functionalized Poly(Ionic Liquids) for Efficient and Stable Perovskite Solar Cells

Abstract

The inevitable ion migration that occurs within ionic polycrystalline perovskite film results in inferior longterm stability of perovskite solar cells (PVSCs) that cannot meet the commercial requirements. Here, a novel poly(ionic liquid) named poly-1-vinyl-3-propyltrimethoxysilane imidazolium chloride (PImIL-SiO) is first introduced into perovskite to strengthen grain boundaries (GBs) and construct dual-functional barriers against internal ion migration and external moisture erosion for fabricating highly efficient and stable PVSCs. PImIL-SiO-containing imidazoliumcations and pendant siloxane groups contribute to passivation of bulk defects and anchoring of GBs, which effectively hinders ion migration channels, thus reducing perovskite film phase separation and device hysteresis. Furthermore, the intrinsically hydrophobic PImIL-SiO automatically forms a secondary protective barrier to endow the perovskite film with ultrahigh moisture corrosion resistance through the hydrolyzation reaction of siloxane with the permeated moisture. Consequently, the PImIL-SiO-modified PVSCs achieve a champion power conversion efficiency (PCE) of 22.46%,accompaniedby excellent thermal andhumidity stabilities where the non-encapsulated devices retain 87%of the initial PCE after aging at 85°C for 250 h and >85% of the initial PCE over 1100 h in air with a relative humidity of 50-70%.