A Dual Hydrogen-Bonding Molecular Bridge Strategy Enables Efficient and Stable Inverted Organic Solar Cells

Simultaneously achieving high power conversion efficiency (PCE) and robust operational stability in inverted organic solar cells (OSCs) requires precise interfacial engineering to overcome the energy-level misalignment and intrinsic photocatalytic activity of ZnO electron transport layers. Herein, we report a multifunctional molecular bridge strategy utilizing a rationally designed naphthalene diimide derivative, NDI-Me, featuring synergistic methyl and hydroxyl functionalization. Distinct from its analogues (NDI-Ph and NDI-OH), NDI-Me establishes a unique dual hydrogen-bonding network: phenolic hydroxyl groups firmly anchor onto ZnO to passivate surface oxygen vacancies, while simultaneously interacting with fluorine atoms in the photoactive layer to facilitate charge extraction. Coupled with the electron-donating methyl groups, this synergistic interaction effectively reduces the ZnO work function to 4.04 eV and accelerates active layer crystallization kinetics. Consequently, PBDB-TF:BTP-eC9-based OSCs incorporating ZnO/NDI-Me deliver a champion PCE of 18.28%. Crucially, the NDI-Me interface effectively suppresses UV-induced photocatalytic degradation, enabling encapsulated devices to retain 88.7% of their initial efficiency after 1800 h of continuous illumination. This work highlights the potential of hydrogen-bond-mediated molecular bridges in constructing efficient and stable organic photovoltaics.