Hole-extraction embedded ultrathin donor realized highly homogenized dense self-assembled monolayers enabling organic photovoltaic modules with a certified efficiency of 16.1%

Abstract Achieving uniform, large-area interfacial layers remain a definitive barrier to the scalable manufacturing of solution-processed organic photovoltaics (OPVs). Conventional self-assembled monolayers (SAMs) frequently suffer from stochastic aggregation and incomplete coverage when scaled to large-area substrates. Here, we report a "Hole-Extraction Embedded Ultrathin Donor" (HE-UD) strategy, in which the donor and hole-extraction molecules are co-deposited as an ultrathin pre-layer, that leverages sterically guided molecular design to induce the autonomous segregation of carbazole-based interlayers. By designing library of carbazole-phosphonic acid derivatives ( K 1– K 4) with systematically engineered side-chain topologies, we precisely modulate the thermodynamic miscibility between the hole-extraction molecules and the polymer donor. Confining K 1 within a nearly 10 nm sacrificial donor matrix facilitates rapid, physical isolation-driven molecular sedimentation, effectively decoupling interlayer formation from the complex evolution of bulk morphology. This thermodynamically robust stratification circumvents kinetic trapping, enabling small-area devices processed from halogen-free toluene to reach a champion power conversion efficiency (PCE) of 18.7%. Furthermore, this strategy offers a wide processing window compatible with ambient blade-coating, yielding 18.20 cm 2 modules with a certified efficiency of 16.1%, representing the highest reported value to date for large-area OPVs fabricated using interfacial layers based on self-assembled molecules. This work establishes a scalable protocol for the uniform deposition of interfacial layers.