Strain engineering in vapor-deposited perovskites enables self-healing and stable solar cells

Thermally induced tensile strain in perovskite films promotes ion migration and the formation of ion vacancies, causing structural degradation of the perovskite crystal and, consequently, a decline in the performance and stability of perovskite solar cells (PSCs). In this study, we introduce a strain regulation strategy for perovskite thin films using a vapor deposition process, which effectively suppresses defect formation and nonradiative recombination by altering the activation energy for ion migration. We demonstrate that vacancy-related degradation can spontaneously recover through ion redistribution under dark conditions, playing a crucial role in maintaining device stability. The strain-relaxed perovskite films exhibit enhanced ion redistribution and intrinsic self-healing behavior, resulting in improved operational stability under repeated light–dark cycling. By modulating residual strain in vapor-deposited perovskite films, we achieve high-performance inverted PSCs with a power conversion efficiency of 20.2 %, retaining 85 % of their initial performance after 1600 h of continuous operation.