Evaluation of internal quantum efficiency in MAPbI3 single crystals via omnidirectional photoluminescence spectroscopy

Abstract We investigated the internal quantum efficiency of bulk methylammonium lead iodide (MAPbI₃) single crystals using omnidirectional photoluminescence spectroscopy. By analyzing both standard photoluminescence and omnidirectional photoluminescence spectra, the internal quantum efficiency was estimated to reach approximately 49.7%, demonstrating the high radiative efficiency of bulk MAPbI3 crystals. Facet-dependent variations in luminescence efficiency were observed, with the {100} facet exhibiting a significantly higher internal quantum efficiency compared to the {112} facet. Additionally, the excitation power dependence of the external quantum efficiency revealed a reversible decrease in emission at high excitation densities, attributed to Auger recombination. These findings provide new insights into the intrinsic photophysical properties of lead halide perovskites and offer valuable guidance for their application in high-performance optoelectronic devices.