Solution‐Processed Perovskite Microdisk for Coherent Light Emission

Abstract High‐quality semiconductor microdisks (MDs) are of crucial importance for realizing on‐chip coherent light sources. However, the fabrication of all‐inorganic semiconductor circular or circular‐like microdisks (CMDs) with suitable size for optoelectronic applications is still complex and expensive. Herein, a facile ligand‐free antisolvent‐assisted growth method is used to synthesize high‐quality Cs₄PbBr₆ MDs with tunable size and morphology, which is evolved from rhombohedral to octahedral, hexagonal‐like, and circular‐like MDs based on Cl‐containing antisolvents. Significantly, this is the first time that large semiconductor CMDs are synthesized from solution self‐assembled growth at room temperature. These Cs₄PbBr₆ MDs show high‐efficient and stable green emission (522 nm), which should be attributed to the first‐order excitonic emission from embedded CsPbBr₃ nanocrystals (NCs). The distribution of CsPbBr₃ NCs is verified by lattice fringe, crystal data refinement, and time‐resolved photoluminescence analysis. These CsPbBr₃‐in‐Cs₄PbBr₆ CMDs are demonstrated to hold outstanding two‐photon pumped coherent light emission ability with a remarkably low threshold (400 µJ cm⁻²). These findings suggest CsPbBr₃‐in‐Cs₄PbBr₆ MDs have excellent light emission capability and stability toward practical optoelectronic applications, and their tunable morphology and size indicate that solution method is feasible for the fabrication of semiconductor CMDs.