Holmium rare earth metal ion incorporated and ambient-air processed all-inorganic γ-CsPbI2.5Br0.5 perovskite solar cells yielding high efficiency and stable performance

Ambient-air processed highly efficient inorganic perovskite solar cells with holmium rare earth metal ion incorporated γ-CsPbI 2.5 Br 0.5 -based perovskite surpassing 19% power conversion efficiency with improved stability.