Regulating Radial Morphology in Hot-Casting Two-Dimensional Ruddlesden–Popper Perovskite Film Growth for High-Efficient Photovoltaics

Two-dimensional (2D) perovskites have attracted significant attention in recent years due to their promising light harvesting and emissive properties. However, the realization of 2D perovskite crystallization with sufficient coverage and reliable reproducibility remains difficult. In this study, controlling the solvent volatilization to achieve high-quality crystallization with full coverage and lateral homogeneity of 2D Ruddlesden–Popper phase perovskite was effectively achieved. It is found that variations in the solvent evaporation rate give rise to lateral film coverage gradients with the degree of grain fusion during the process of hot-casting. As a result, the obtained photovoltaic efficiency varies due to the growth inhomogeneity across hot-casting thin films from center to edge. By adjusting the temperature of the casting perovskite precursor, film inhomogeneity and device performance variation can be alleviated. Regulating radial morphology across hot-casting thin films will enable coating techniques amenable to the solution process for robust reproducibility.