Tin-lead metal halide perovskites show promise as light-absorbing materials with a tunable band gap (1.2-1.4 eV) for efficient perovskite solar cells (PSCs) with less toxicity. However, the instability of the tin(II) ionic state limits the lifetime of their PSCs, which reduces their real-world feasibility. Herein, indium(III) iodide (InI