Broad spectrum light-trapping ternary polymer solar cells based on self-assembled nano-ridged active layer

Ternary blend polymer solar cells (TPSCs) comprising one donor and two fullerene acceptors is efficient method for improving the power conversion efficiency (PCE). In this paper, the PTB7-Th-based TPSCs which is incorporating PC70BM and PC60BM as mixed acceptors are fabricated and investigated. Impressively, the remarkable self-assembled nano-ridged (SANR) structures are discovered in the active layer with the weight ratio of 50% PC60BM in fullerenes. Thanks to the enlarged interface area, enhanced light absorption and balanced carrier transport, the PTB7-Th:PC70BM:PC60BM TPSCs with the SANR active layer gives an optimal PCE of 9.68%. In addition, it is worth emphasizing that by combining the textured-ZnO with the SANR active layer, a double ridge superimposed system (DRSS) with broad spectrum light trapping characteristic is constructed, which can further enhance the light absorption of the devices. Finally, benefiting from the further increase in short circuit current density (J(sc)), the PTB7-Th:PC70BM:PC60BM TPSCs with the DRSS gives an optimal PCE of 10.68%. This work provides a feasible ternary strategy to increase the devices performances and is proved be a simple and efficient strategy for fabricating PTB7-Th:PC70BM:PC60BM TPSCs with SANR active layer.