Solution-processed carbon dots based cathode interlayer for high efficiency inverted organic solar cells with improved photostability

In this work, carbon dots (C-dots) with amino groups are synthesized by one-pot hydrothermal method, which could be treated in aqueous solution. The new material is used as cathode interlayer in organic solar cells (OSCs) for the first time. The C-dots cathode interlayer reduces the work function, improves the extraction and transportation of charge carriers, and reduces the recombination of charge carriers in device. As a result, the champion power conversion efficiency (PCE) of the C-dots based device is 15.41% when using PM6:Y6 as active layer. In addition, after 1 h of continuous UV illumination, 97.5% of the original PCE for C-dots based device could be maintained while devices based on ZnO cathode interlayer only remained 80.9%, indicating that C-dots are potential candidates as stable and efficient cathode interlayer to overcome the inherent poor photostability drawback of ZnO.