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

Abstract

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.