All inorganic CsPbI₃ perovskite solar cells with reduced mobile ion concentration and film stress

Here, we study the impact of a polyvinylpyrrolidone (PVP) additive on cesium-based lead halide perovskites. We demonstrate the control of phase, morphology, film stress, and ion concentration under accelerated aging with the use of PVP in CsPbI₃. The addition of PVP in all-inorganic metal halide perovskites (MHP) further induces a residual compressive film stress, a factor that is correlated with improved film stability. The removal of PVP increased the stress based on a contraction in the film. Under thermal cycling, thermal aging, and light-induced aging, all-inorganic MHP films experienced negligible bandgap change and comparable ion behavior with and without PVP removal.