Understanding Transient Photoluminescence in Halide Perovskite Layer Stacks and Solar Cells

Abstract

While transient photoluminescence (TPL) measurements are a very popular tool to monitor the charge-carrier dynamics in the field of halide perovskite photovoltaics, interpretation of data obtained on multilayer samples is highly challenging due to the superposition of various effects that modulate the charge-carrier concentration in the perovskite layer and thereby the measured photoluminescence (PL). These effects include bulk and interfacial recombination, charge transfer to electron- or hole transport layers, and capacitive charging or discharging. Here, numerical simulations with Sentauraus TCAD, analytical solutions, and experimental data with a dynamic range of ≈7 orders of magnitude on a variety of different sample geometries, from perovskite films on glass to full devices, are combined to present an improved understanding of this method. A presentation of the decay time of the TPL decay that follows from taking the derivative of the photoluminescence at every time is proposed. Plotting this decay time as a function of the time-dependent quasi-Fermi-level splitting enables distinguishing between the different contributions of radiative and non-radiative recombination as well as charge extraction and capacitive effects to the decay.