Microscopic Intricacies of Self-Healing in Halide Perovskite–Charge-Transport-Layer Heterostructures

Abstract The operational stability of halide perovskite photovoltaics is critically limited by progressive defect generation and nonradiative losses. Self-healing of defects offers a promising route to sustained performance, yet the coupled microscopic processes underlying it remain poorly understood, particularly at device-relevant interfaces. Here, we elucidate self-healing and defect evolution in photodamaged triple-cation mixed-halide (TCMH) perovskite films and their device-relevant charge-transport-layer (CTL) heterostructures. Using correlation clustering imaging (CLIM), our recently developed microscopic functional imaging tool, we map spatiotemporal photoluminescence heterogeneity to track defect dynamics. Each CTL distinctly modulates local trap activity, healing kinetics, and spectral redistribution in the TCMH layer, and the heterostructures exhibit faster optical recovery than pristine films, beneficial for device resilience. Healing follows biphasic kinetics, with fast electronic relaxation over minutes to tens of minutes and slower ionic redistribution and lattice relaxation over hours. Although quantitative device stability improvements are not established here, these microscopic insights into dynamic evolution of defects and ion redistribution at interfaces provide a framework for rationally designing stable perovskite optoelectronics.