Photo-Tautomerization-Driven Energy Transfer at the Hole-Transport Interface Stabilizes Efficient Inverted Perovskite...

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 [PbI₆]^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 cm²) 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 cm² PSC and 23.00% for a 12.96 cm² 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.