The structure-performance correlation of bulk-heterojunction organic solar cells with multi-length-scale morphology

We build a general multi-length-scale morphology model with mixing phase and pure phase fibril structure, and simulate corresponding organic solar cells performance. Systematical multi-length-scale morphology optimization process by changing the proportion of mixing phase and pure phase in different period width cases shows a clear correlation between period width and device performance that a smaller period width with appropriate proportion of mixing phase and fibril structure is advantageous to achieve high-performance devices. Experiments on multiple donor/acceptor blends have been carried out by varying the composition and processing condition, which afford good structure-performance correlation that supports the model prediction. It is demonstrated that building such a multi-length-scale morphology merging the synergistic effects of mixing and pure phases is indeed an imperative avenue to improve device efficiency.