In situ dynamic regulation of strain at the buried interface of stable perovskite solar cells

The commercialization of perovskite photovoltaics faces significant hurdles due to device degradation under environmental stressors, such as illumination, humidity and heat, which represents a core challenge for industrial applications. Here we present a conformational engineering strategy targeting the buried interface of perovskite solar cells and based on the structural evolution of additives—from 1,1-diphenylethylene to 1-octyl-2-(1-phenylvinyl)benzene and diethylamino hydroxybenzoyl hexyl benzoate. We decouple the contributions of the additives, including ultraviolet shielding, strain regulation and chemical passivation. In conjunction with in situ characterization, we reveal that dynamic interfacial strain regulation plays a major role in improving device stability during light–dark cycling. Our devices achieve power conversion efficiencies of 26.47% and 22.67%, for active areas of 0.09 cm 2 and 20.5 cm 2 , respectively. Under maximum power point tracking, small-area devices maintain 96.2% of their initial power conversion efficiency after 1,132 h of testing in ISOS-L-1I (continuous illumination) and 88.8% after 348 h in ISOS-LC-1 (12-h day–night cycling). This research establishes an innovative design paradigm for stable and efficient perovskite solar cells through a multifunctional strategy driven by conformational engineering.