Comparative Analysis of the Defect Landscape of Solution-Processed and Evaporated Lead Halide Perovskite Films

High Resolution Image Download MS PowerPoint Slide Herein, we analyze the defect structure of evaporated and solution-processed methyl ammonium lead iodide perovskite films using exclusively non-invasive photophysical analysis. By using a representation of time-resolved photoluminescence data in the form of an instantaneous decay rate vs a variable that depends on the density of carriers, we are able to identify patterns that can be univocally assigned to the presence of either shallow or deep traps. Furthermore, it allows quantifying the relative contribution of each defect type to carrier recombination. We find that as-synthesized solution-processed films present balanced concentrations of shallow and deep traps, while the latter are prevalent in evaporated ones. This defect landscape changes radically when films are exposed to the ambient atmosphere. The validity of this approach is demonstrated by employing the extracted values of the relevant photophysical parameters to accurately reproduce the experimentally observed dependence of the photoluminescence emission efficiency on the excitation intensity.