Origin of Amplified Spontaneous Emission Degradation in MAPbBr3 Thin Films under Nanosecond-UV Laser Irradiation

Abstract

Hybrid halide perovskites have achieved excellent efficiencies and remarkable performances, not just in photovoltaic cells but also in light-emitting devices, such as light-emitting diodes, light-emitting transistors, and lasers. The lack of long-term stability is the main limitation for the commercial application of perovskite devices. While several works have investigated the origin of the degradation of perovskites in regard to solar cell applications, the operational stability of perovskites under the optical pumping regime necessary for optical gain and lasing is largely unexplored. In this work, we investigate the origin of the photodegradation of amplified spontaneous emissions (ASE) in MAPbBr3 thin films under nanosecond-UV laser irradiation as a function of the pump excitation density in different environments (air and vacuum). The correlation between the observed ASE operational stability and the irradiation-induced variations in the local morphology and emission properties allowed us to demonstrate that the main process leading to ASE quenching is related to the film melting induced by localized heating. This also induces a bromine loss. Our results are relevant for the development of suitable strategies to improve the ASE values and the lasing operational stability of lead halide perovskite films.