Bright and Efficient CsSnBr3 Light-Emitting Diodes Enabled by Interfacial Reaction-Assisted Crystallization

Tin-based perovskites are more environmentally friendly than their lead-based alternatives. Perovskite light-emitting diodes (PeLEDs) using iodide-based tin perovskites have achieved considerable advancements in efficiency. However, PeLEDs using bromide-based tin perovskites have not progressed as rapidly, primarily due to challenges in controlling their crystallization processes. Here, an interfacial reaction-assisted crystallization method is introduced to achieve bright and efficient CsSnBr 3 PeLEDs. It is started by forming an intermediate phase through the coordination of SnBr 2 with ethylenediamine derivatives. Subsequently, a protonation reaction is designed between the intermediate phase and the acidic polyethylenedioxythiophene: poly(styrene sulfonate) hole-transport layer to generate high-quality CsSnBr 3 films. Additionally, the use of potassium thiocyanate additives effectively enhances the photoluminescence efficiency of the CsSnBr 3 films. These efforts result in CsSnBr 3 -based PeLEDs achieving a maximum luminance of 787 cd m −2 and a peak external quantum efficiency of 0.91%, demonstrating the most efficient and brightest CsSnBr 3 -based PeLEDs to date. This work opens an avenue to better control the crystallization of tin-based perovskite.