Interpreting Halide Perovskite Semiconductor Photoluminescence Kinetics

Drawing from both experimental data and simulation, we highlight best practices for fitting time-resolved photoluminescence (TRPL) decays of halide perovskite semiconductors, which are now widely studied for applications in photovoltaics and light-emitting diodes (LEDs). First, at low excitation intensities, high-quality perovskites often show pseudo-first-order kinetics, consistent with classic minority carrier lifetimes. Second, multiexponential decays, frequently observed at low excitation intensities, often have significant contributions from spatial heterogeneity. We recommend fitting such decays with stretched exponentials, where the stretching factor (beta) can be used to characterize the heterogeneity of the local lifetime distribution. Third, PL decay kinetics can depend on the excitation wavelength. We discuss how penetration depth, carrier diffusion, and surface recombination affect measurements and make recommendations for choosing experimental parameters suited to the question at hand. Accounting for these factors will provide a more reliable and physical interpretation of carrier recombination and better understanding of nonradiative losses in perovskite semiconductors.