Researchers have developed an electron transport layer using fluorinated carbon dots that pushed inverted organic solar cells to a 20.01% power conversion efficiency, according to research published in Nature Communications. The inverted device recorded a certified power conversion efficiency of 19.78%.
The team incorporated in-situ fluorinated carbon dots into a coherent polymer to construct a crystallinity-enhanced network through strong hydrogen bonding. Named netFCD, the material functions as an all-in-one electron transport layer. It provides electrical and mechanical contact across all-sided interfaces, covering both the cathode and the active layer, while establishing barrier-free operation with high electron mobility and hole blocking.
Chemical measurements showed that the reduced basicity of the netFCD layer prevents unexpected interfacial reactions with non-fullerene acceptors. The resulting solar cells retained 85% of their initial power conversion efficiency after 1,800 hours of operation in environments with 80 ± 5% humidity. In flexible inverted designs, the cells maintained 95% of their initial efficiency after enduring 10,000 bending cycles.
Mengqi Cui, Yi Yang, Ruijia Zhang, Xinjun He, Wallace C. H. Choy, and Alex K.-Y. Jen led the study across the University of Hong Kong, City University of Hong Kong, The Hong Kong University of Science and Technology, Shandong University of Technology, and the Shanghai Institute of Optics and Fine Mechanics. Supporting grants came from the Research Grants Council of Hong Kong, the Innovation and Technology Commission of Hong Kong, and the University Grant Council of the University of Hong Kong.
