Coordination Cathode Interlayer Enhancing the Stability of Air-Processed Organic Photovoltaics

Moisture in the air can harm the photovoltaic performance of organic photovoltaic (OPV) devices due to the serious charge recombination induced by moisture. The interface between the electron transport layer (ETL) and the top electrode is easily invaded by moisture since it is the outermost interlayer of the device. Here, we report an effective strategy to enhance the moisture resistance of the device by modifying the interface between the ETL of ZnO nanoparticles (ZnO NPs) and the electrode with a coordination interlayer. This strategy dramatically strengthens the adhesion between the ZnO NPs layer and the Ag electrode, thereby reducing the invasion of moisture at the interface and enhancing the device's stability in air. After introducing the coordination interlayer, the power conversion efficiency (PCE) of the unencapsulated devices increased substantially from 0.1% to 16.3% when measured under open-air conditions. Notably, the unencapsulated devices retained 85% and 56% of the initial PCE after 14 days and 1 year of storage in the air, respectively.