Nonlinear photocarrier dynamics and the role of shallow traps in mixed-halide mixed-cation hybrid perovskites

We examine the role of surface passivation on carrier trapping and nonlinear recombination dynamics in hybrid metal-halide perovskites by means of excitation correlation photoluminescence (ECPL) spectroscopy. We find that carrier trapping occurs on sub-nanosecond timescales in both control (unpassivated) and passivated samples, which is consistent within a shallow-trap model. However, the impact of passivation has a direct effect on both shallow and deep traps. Our results reveal that the effect of passivation of deep traps is responsible for the increase of the carrier lifetimes, while the passivation of shallow traps reduces the excitation density required for shallow-trap saturation. Our work demonstrates how ECPL provides details about the passivation of shallow traps beyond those available via conventional time-resolved photoluminescence techniques.

Automated summary

Through ECPL spectroscopy, the role of surface passivation in carrier trapping and nonlinear recombination dynamics in hybrid metal-halide perovskites was investigated. Passivation was found to have a direct impact on both shallow and deep traps, with passivation of deep traps increasing carrier lifetimes and passivation of shallow traps reducing the excitation density required for saturation. The study demonstrates the ability of ECPL to provide detailed information on the passivation of shallow traps beyond conventional time-resolved photoluminescence techniques.