Extracting Decay-Rate Ratios from Photoluminescence Quantum Efficiency Measurements in Optoelectronic Semiconductors

Abstract

Recombination rates in optoelectronic semiconductors are typically recorded using time-intensive and expensive measurements. Here we present a method to extract decay rate ratios in a facile and rapid manner using only photoluminescence quantum efficiency measurements, which we demonstrate on halide perovskite thin-film samples. We combine these ratios with time-resolved photoluminescence data to extract absolute recombination rates, with excellent agreement when our approach is benchmarked against the more time- and infrastructure-intensive technique of transient absorption spectroscopy. This approach also enables direct quantification of the ratio between total second-order and radiative second-order recombination rates. We demonstrate that radiative recombination is only a fraction of total second-order recombination in the range of halide perovskite samples relevant for photovoltaics. We showcase the implications of rapid extraction of decay rates by extracting decay rate ratios on a microscale and by calculating the expected maximum efficiency of a solar cell fabricated from a measured perovskite film. We show that reducing first-order losses will significantly improve solar cell efficiency for our samples until time-resolved photoluminescence lifetimes are longer than approximately 1 µs (at low excitation pulse intensity), at which point second-order nonradiative recombination limits the efficiency of perovskite solar cells. This work presents a framework for rapidly screening optoelectronic semiconductors with techniques widely accessible to many research groups, identifies decay processes that would otherwise be missed, and directly relates the extracted values to predicted device performance metrics.