The efficiency and photostability of all‐inorganic mixed‐halide perovskite solar cells (PVSCs) can be simultaneously enhanced by introducing an amino‐functionalized polymer PN4N as a novel cathode interlayer and dopant‐free PDCBT hole‐transporting layer. The favorable interaction between perovskite crystal and PN4N/PDCBT can effectively improve CsPbI2Br film quality, with power conversion efficiency over 16%.
