Photo‐Tautomerization‐Driven Energy Transfer at the Hole‐Transport Interface Stabilizes Efficient Inverted Perovskite Solar Cells

ABSTRACT Perovskite solar cells (PSCs) offer high power conversion efficiencies (PCEs) but suffer from UV‐induced degradation, hindering their practical deployment. Here, we introduce a Förster resonance energy transfer (FRET) channel at the hole‐transport layer (HTL)/perovskite interface by incorporating the ultraviolet absorber N‐(2‐ethoxyphenyl)‐N’‐(2‐ethylphenyl)oxamide (UV‐312). Under UV irradiation, UV‐312 adopts an enol‐resonant configuration that facilitates ultrafast FRET (∼20 ps) to the interface. This process promotes charge separation and suppresses UV‐induced Pb–I bond dissociation, thereby preserving the [PbI 6 ] 4– octahedral framework and enhancing UV‐stress resilience. Moreover, the rigid, extended conjugation of UV‐312 mitigates MeO‐2PACz aggregation, optimizing interfacial energy‐level alignment and minimizing stress inhomogeneity. Consequently, the champion device (aperture area: 0.09 cm 2 ) achieves a remarkable PCE of 27.05% with a high open‑circuit voltage of 1.186 V and a minimal non‐radiative voltage loss of only 61 mV. Impressively, the performance scales to 25.08% for a 1 cm 2 PSC and 23.00% for a 12.96 cm 2 mini‑module, accompanied by robust operational stability under continuous light, heat, and UV stress. This work redefines UV absorbers as active energy‐management units, offering a unified approach to simultaneously address efficiency and stability issues in perovskite photovoltaics.