Stabilizing Buried Contacts in Hybrid‐Deposited Perovskite Solar Cells via Amidinium‐Based Passivation

Monolithic integration of perovskite solar cells (PSCs) with textured silicon is essential for commercializing perovskite/silicon tandem photovoltaics. Hybrid evaporation–solution processing enables conformal perovskite deposition on textured surfaces, but residual PbI 2 at the buried interface limits performance and stability. Here, we introduce 2,4‐difluorobenzamidine hydrochloride (2,4‐FPhFACl) into self‐assembled monolayers (SAMs) as a buried hole‐selective contact to improve interface quality. The amidinium groups strongly interact with the perovskite, suppressing thermal decomposition and eliminating PbI 2 formation. This approach enhances surface passivation and energy‐level alignment. Wide‐bandgap (1.65 eV) devices achieve a power conversion efficiency (PCE) of 20.19% and retain 80% efficiency after 2000 h at 85°C. Applied to fully textured perovskite/silicon tandems, this strategy delivers a champion PCE of 29.91% (1.04 cm 2 ), offering a scalable route to high‐performance tandem photovoltaics.