Amplified Spontaneous Emission Properties of Solution Processed CsPbBr3 Perovskite Thin Films

Metal halide perovskites are currently emerging as highly promising optoelectronic materials. It has been recently demonstrated that fully inorganic solution processed CsPbBr3 perovskite thin films show good electroluminescence properties combined with high thermal stability. In this work, we investigate in details the amplified spontaneous emission (ASE) properties of CsPbBr3 perovskite thin films, as a function of the temperature and the trap density, modified by changing the CsBr–PbBr2 precursor concentration. ASE is observed in samples from both CsBr-rich solution (low trap density) and equimolar solution (higher trap density), up to about 150 K, with a minimum threshold of 26 and 29 μJ cm–2 at 10 K, respectively. However, the different distribution of defect states, mainly above the first exciton level in the former and below it in the latter, strongly improved optical gain at 10 K and changed the ASE temperature dependence of CsBr-rich films.