Universal Dynamic Liquid Interface for Healing Perovskite Solar Cells

Abstract

Abstract Healing charge‐selective contact interfaces in perovskite solar cells (PSCs) highly determines the power conversion efficiency (PCE) and stability. However, the state‐of‐the‐art strategies are often static by one‐off formation of a functional interlayer, which delivers fixed interfacial properties during the subsequent operation. As a result, defects formed in‐service will gradually deteriorate the photovoltaic performances. Herein, a dynamic healing interface (DHI) is presented by incorporating a low‐melting‐point small molecule onto perovskite film surface for highly efficient and stable PSCs. Arising from the reduced non‐radiative recombination, the DHI boosts the PCE to 12.05% for an all‐inorganic CsPbIBr 2 solar cell and 14.14% for a CsPbI 2 Br cell, as well as 23.37% for an FA 0.92 MA 0.08 PbI 3 (FA = formamidinium, MA = methylammonium) cell. The solid‐to‐liquid phase conversion of DHI at elevated temperature causes a longitudinal infiltration into the bulk perovskite film to maximize the charge extraction, passivate defects at grain boundaries, and suppress ion migration. Furthermore, the stability is remarkably enhanced under air, heat, and persistent light‐irradiation conditions, paving a universal strategy for advanced perovskite‐based optoelectronics.