One-Step Preparation of High-Stability CsPbX 3 /CsPb 2 X 5 Composite Microplates with Tunable Emission

The core-shell structure is an effective means to improve the stability and optoelectronic properties of cesium lead halide (CsPbX (X = Cl, Br, I)) perovskite quantum dots (QDs). However, confined by the ionic radius differences, developing a core-shell packaging strategy suitable for the entire CsPbX system remains a challenge. In this study, we introduce an optimized hot-injection method for the epitaxial growth of the CsPb X substrate on CsPbX surfaces, achieved by precisely controlling the reaction time and the ratio of lead halide precursors. The synthesized CsPbX /CsPb X composite microplates exhibit an emission light spectrum that covers the entire visible range. Crystallographic analyses and density functional theory (DFT) calculations reveal a minimal lattice mismatch between the (002) plane of CsPb X and the (1 0) plane of CsPbX , facilitating the formation of high-quality type-I heterojunctions. Furthermore, introducing Cl and I significantly alters the surface energy of CsPb X 's (110) plane, leading to an evolutionary morphological shift of grains from circular to square microplates. Benefiting from the passivation of CsPb X , the composites exhibit enhanced optical properties and stability. Subsequently, the white light-emitting diode prepared using the CsPbX /CsPb X composite microplates has a high luminescence efficiency of 136.76 lm/W and the PL intensity decays by only 3.6% after 24 h of continuous operation.