Environment‐Dependent Metastable Nonradiative Recombination Centers in Perovskites Revealed by Photoluminescence Blinking

Abstract

Organometal halide perovskites are promising materials for optoelectronic devices; however, nonradiative recombination under various atmospheric conditions severely affects the photostability of the materials and limits their potential applications. Further efforts to improve the stability are restricted by limited knowledge on nonradiative mechanisms. Herein, the contribution of nonradiative centers in photoluminescence (PL) response of methylammonium lead iodide (MAPbI3) crystals is resolved by studying atmosphere‐dependent PL blinking dynamics at single‐particle level. It is observed that interaction with nitrogen (N2) under illumination leads to PL quenching, revealing that N2 would activate highly efficient nonradiative recombination centers, which are previously passivated by oxygen (O2). In contrast, exposure to O2 results in the accumulation of the numbers of less‐efficient quenchers, leading to smooth PL decline. In a phenomenological model, the observed PL fluctuation is attributed to the switch of nonradiative recombination centers between their active and passive states and the change of the relative energy level. It is proposed that variation of stoichiometry from crystal to crystal causes the diverse PL response under different atmospheres. The results provide fundamental insights into the correlation between the nonradiative recombination sites and surrounding atmosphere conditions and may help for further improving the material quality and processing.