19.36% Efficiency in Binary Organic Solar Cells with Amine‐Hydroxy‐Substituted Perylene Diimide‐Based Interface Layers

Organic solar cells (OSCs) have garnered extensive attention and experienced rapid development due to their immense potential in addressing future energy challenges. Among the critical components of OSCs, cathode interfacial materials (CIMs) play a pivotal role in reducing the work function of electrodes and enhancing charge carrier mobility. High‐polarity functional groups are commonly incorporated into CIMs designs to improve interfacial contact with the active layer and mitigate the power loss at metal electrodes. Herein, we report a hydrogen‐bonding interfacial material, hydroxyl‐ethylenediamine‐functionalized perylene diimide (PDIN‐OH), which further reduces the cathode work function while maintaining excellent interfacial contact with the active layer. The outstanding conductivity of PDIN‐OH, combined with its doping interaction with acceptor materials, significantly enhances its tolerance to thick films. In binary OSCs using the classical active layers PM6:Y6 and D18:L8‐BO, devices incorporating PDIN‐OH achieved remarkable power conversion efficiencies (PCEs) of 17.51% and 19.36%, respectively, along with outstanding stability. These findings indicate the potential of PDIN‐OH as an efficient and stable CIM, offering a promising pathway to enhance OSC performance and promote their practical applications.