Enhancing Luminescence Efficiency by Controlled Island Formation of CsPbBr₃ Perovskite

Abstract CsPbBr₃ is an inorganic perovskite material that is promising for light‐emitting applications. Such applications are known to benefit from an island‐type active layer structure, which enhances the device's light emission efficiency. Here, the impact of the environment on the island formation in thermally deposited bilayers of CsPbBr₃/LiBr is investigated. It is demonstrated that the island formation occurs only in humid environments, leading to an enhancement of the photoluminescence quantum yield by a factor of 350. Time‐resolved grazing‐incidence wide‐angle X‐ray scattering experiments document the island growth process and reveal that the LiBr has already changed the perovskite crystal orientation prior to the island formation.