Niobium Incorporation into CsPbI2Br for Stable and Efficient All-Inorganic Perovskite Solar Cells

All-inorganic perovskites are attracting increasing attention due to their superior thermal stability than that of the traditional CH 3 NH 3 PbI 3, while their inferior phase stability in ambient conditions is still an unsolved issue. Here, for the first time, we report the incorporation of niobium (Nb 5+ ) ions into the CsPbI 2 Br perovskite. Results indicate that Nb 5+ can effectively stabilize the photoactive α-CsPbI 2 Br phase by the possible substitution of Pb 2+ . With 0.5% Nb doping, the carbon electrode-based all-inorganic perovskite solar cells achieved a high photoconversion efficiency value of 10.42%, 15% higher than that of the control device. The Nb 5+ incorporation reduces the charge recombination in the perovskite, leading to a champion V oc value of 1.27 V and a negligible hysteresis effect. This work explicates the high compatibility of all-inorganic perovskite materials and unlocks the opportunities for the use of high-valence ions for perovskite property modification.