Controlling Nucleation and Crystallization of CsPbI3 Perovskites for Efficient Inverted Solar Cells

The unfavorable morphology and high crystallization temperature (Tc) of inorganic perovskites pose a significant challenge to their widespread application in photovoltaics. In this study, an effective approach is proposed to enhance the morphology of cesium lead triiodide (CsPbI3) while lowering its Tc. By introducing dimethylammonium acetate into the perovskite precursor solution, a rapid nucleation stage is facilitated, and significantly enhances the crystal growth of the intermediate phase at low annealing temperatures, followed by a slow crystal growth stage at higher annealing temperatures. This results in a uniform and dense morphology in CsPbI3 perovskite films with enhanced crystallinity, simultaneously reducing the Tc from 200 to 150 °C. Applying this approach in positive‐intrinsic‐negative (p‐i‐n) inverted cells yields a high power conversion efficiency of 19.23%. Importantly, these cells exhibit significantly enhanced stability, even under stress at 85 °C.