Enhanced Photoluminescence of Cesium Lead Halide Perovskites by Quasi‐3D Photonic Crystals

Abstract Cesium lead halide perovskite nanocrystals have emerged as one of the most promising candidates for manufacturing portable lasers and light sources. In order to harness and exploit their photoluminescence more effectively, the nanocrystals are often accompanied by a photonic scheme that improves light emission. In this work, a quasi‐3D photonic crystal is introduced which is composed of a 2D‐grating on top of a distributed Bragg reflector (DBR) and provides a greater photoluminescence enhancement than the isolated architectures alone. The quasi‐3D photonic crystals support both Rayleigh‐Wood anomalies and guided modes that populate the photonic bandgap of the Bragg mirror, all of them capable of enhancing the outcoupling of light from the emitting layer. In order to demonstrate the benefits of the quasi‐3D system, the authors prepare 2D‐gratings, DBRs, and quasi‐3D photonic crystals covered with metal halide perovskite nanocrystals and study the photoluminescence enhancement produced in each case. Interestingly, the quasi‐3D structure exhibits a photoluminescence enhancement of 16 times and an increase in spontaneous emission rate, greatly exceeding the values observed for the separate components.