18.18 % Efficiency of organic solar cells based on PM6:Y6 with Syringic acid modified ZnO

Zinc oxide (ZnO) is used as an electron transport layer (ETL) in inverted organic solar cells (IOSCs) owing to its excellent performance, such as good light transmission and high conductivity, while its surface defects and photocatalytic properties limit the development of IOSCs. Herein, we apply an antioxidant, syringic acid (SA), to modify the surface of ZnO film, which observably improve the efficiency and stability of IOSCs. It is found that SA can effectively passivate the surface defects of ZnO and optimize surface morphology, as well as reduce the work function (W F ) of ZnO resulting in an improvement of the charge transport of IOSCs. The power conversion efficiency (PCE) of PM6:Y6-based IOSCs is increased from 16.19 % to 18.18 %, it is the highest PCE values of the single-junction IOSCs based on PM6:Y6 system as reported. Meanwhile, the photostability of the device is markedly improved due to SA could suppress the photocatalytic of ZnO under the ultraviolet aging.