Buried Interface Regulation with a Supramolecular Assembled Template Enables High‐Performance Perovskite Solar Cells for Minimizing the VOC Deficit

Abstract Despite the rapid development of perovskite solar cells (PSCs) in the past decade, the open‐circuit voltage ( V OC ) of PSCs still lags behind the theoretical Shockley–Queisser limit. Energy‐level mismatch and unwanted nonradiative recombination at key interfaces are the main factors detrimental to V OC . Herein, a perovskite crystallization‐driven template is constructed at the SnO 2 /perovskite buried interface through a self‐assembled amphiphilic phosphonate derivative. The highly oriented supramolecular template grows from an evolutionary selection growth via solid–solid phase transition. This strategy induces perovskite crystallization into a highly preferred (100) orientation toward out‐of‐plane direction and facilitated carrier extraction and transfer due to the elimination of energy barrier. This self‐assembly process positively passivates the intrinsic surface defects at the SnO 2 /perovskite interface through the functionalized moieties, a marked contrast to the passive effect achieved via incidental contacts in conventional passivation methods. As a result, PSCs with buried interface modification exhibit a promising PCE of 25.34%, with a maximum V OC of 1.23 V, corresponding to a mere 0.306 V deficit (for perovskite bandgap of 1.536 eV), reaching 97.2% of the theoretical V OC limit. This strategy spontaneously improves the long‐term operational stability of PSCs under thermal and moisture stress (ISOS‐L‐3: MPP, 65 °C, 50% RH, T 92 lifetime exceeding 1200 h).