Probing the properties of polymer/non-fullerene/fullerene bulk heterojunction ternary blend solar cells, study of varied blend ratios of PBDB-T:ITIC-Th:PC71BM

A major noble way to realizing high-efficiency organic solar cell device is the use of ternary blends with non-fullerene acceptors. Although offset in the band gap (E-gap) of the donor/acceptor material is negligible, it still exhibits ultra-fast and efficient charge separation. Regardless of the progress made, device optimization and fundamental understanding of the role of structural configurations in charge transport mechanisms is still on the way. The performances and stability of such devices largely depend on the nanoscale solid-state interpenetrating morphology of their donor/acceptor components within the photoactive region. Here, we analyze the effects of the second acceptor material PC71BM which is fullerene derivative on the nano-morphology within the bulk-heterojunction active layer made of PBDB-T (as donor) and non-fullerene derivative ITIC-Th (as acceptor) as well as the photovoltaic performance. Upon varying the blend ratio, 2:1:1 ratio showed a remarkable performance with more photo-generated current resulting from the favorable nano-scaled interpenetrating network with less traps as can be visualized in Fig. 1.