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.

Automated summary

Carbon dots (C-dots) with amino groups were synthesized by hydrothermal method and used as cathode interlayer in organic solar cells (OSCs) for the first time. The C-dots interlayer reduced the work function, improved charge carrier extraction and transportation, and reduced charge carrier recombination, resulting in a champion power conversion efficiency (PCE) of 15.41% when using PM6:Y6 as active layer. Additionally, the C-dots based device maintained 97.5% of its original PCE after 1 hour of continuous UV illumination, whereas devices with ZnO interlayer only maintained 80.9%, indicating that C-dots are potential stable and efficient cathode interlayers.