Dynamic Non‐Covalent Interactions at Oxide–Organic Heterointerfaces Enable Simultaneous Dielectric Enhancement and Mechanical Reinforcement of Organic Photovoltaic Devices and Modules

ABSTRACT Flexible organic photovoltaics (OPVs) demand both high efficiency and mechanical robustness, yet rigid non‐fullerene acceptor blends commonly suffer from an efficiency–mechanics trade‐off. Here, trace Al 2 O 3 nanofillers are incorporated into the PM6:BTP‐eC9 active layer to simultaneously enhance dielectric screening, charge‐transport balance, and mechanical energy dissipation. The nanofillers raise the relative permittivity from 2.48 to 2.78, promote exciton dissociation, suppress bimolecular and trap‐assisted recombination, and improve charge‐transport balance, raising the power conversion efficiency (PCE) from 16.1% to 17.0% for flexible devices, while increasing that of the corresponding rigid devices from 19.4% to 20.3%. Variable‐temperature FT‐IR spectroscopy and multiscale simulations provide evidence for thermally responsive and partially reversible interactions between Al 2 O 3 surface hydroxyls and polar moieties in the photoactive matrix, which are consistent with hydrogen bonding. These interactions are proposed to enhance intermolecular cohesion, homogenize stress distribution, and suppress crack initiation and propagation, increasing the crack‐onset strain (COS) from 4.6% to 12.0% and nearly quadrupling toughness. The strategy translates to flexible devices retaining 87.3% of their initial efficiency after 2000 bending cycles, intrinsically stretchable devices retaining 79.0% after 200 cycles at 5% strain, and an 11.4%‐efficient flexible module with a 100 cm 2 footprint and 68 cm 2 effective active area.