Tunable ultra-uniform Cs4PbBr6 perovskites with efficient photoluminescence and excellent stability for high-performance white light-emitting diodes

Abstract

Metal halide perovskites are a new class of promising materials in optoelectronic applications. As the optoelectronic properties of lead halide perovskites are determined largely by their morphology, the morphology of perovskites is crucial for their applications. However, the morphology-controllable synthesis of Cs₄PbBr₆ perovskites has been scarcely reported so far. Here, zero-dimensional Cs₄PbBr₆ perovskite microcrystals with tunable size and ultra-uniform morphology were synthesized via a facile precipitation method. The as-prepared Cs₄PbBr₆ microcrystals possess high photoluminescence quantum yields of up to 98% and excellent stability. The content of ligands plays a dominant role in the solubility of PbBr₂ and can compete with Cs⁺ ions for the surface passivation of Cs₄PbBr₆ microcrystals, thus modulating the kinetics of the reaction to influence the size and phase of the final products. Meanwhile, the synthesized Cs₄PbBr₆ microcrystals have outstanding thermal stability compared with CsPbBr₃ perovskites. Highly emissive hexagonal Cs₄PbBr₆ microcrystals with excellent stability were used as phosphors for white light emitting diodes (WLEDs), and the luminous efficiency of the WLED device was determined to be as high as 116.84 lm W⁻¹. This study provides an effective and facile approach to fabricate stable Cs₄PbBr₆ microcrystals with tunable size and excellent photoluminescence properties.