Ternary strategy: An analogue as third component reduces the energy loss and improves the efficiency of polymer solar cells

Ternary strategy is a convenient and effective method to boost the performance of polymer solar cells (PSCs). Utilizing a ternary strategy to trade-off between the energy loss and the efficiency of devices however requires further exploration. Here, through the hydroxyl (-OH) and acetoxy (-OCOMe) substitution at beta-position of the IC terminal group, we developed two new synthetic acceptors, BTIC-OH-beta and BTICOCOMe-beta, which were designed to confine the morphology aggregation. Introduction of an analogue as the third component provides a simple but efficient way to further balance the short current density (J(sc)) and open-circuit voltage (V-oc), leading to a champion efficiency based on PBDB-T:PBDB-TF:BTIC-OCOMe-beta, effectively as high as 12.45%. The results were examined mainly in terms of the morphology characterization, electroluminescence external quantum efficiency (EQE(EL)), steady-state photoluminescence (PL) and transient technology. It suggested fine-tuning of the morphology by ratio modulation, reduction of the energy loss, construction of a promising pathway for charge transfer in the ternary system and enhancing the carrier extraction. In this way, a ternary strategy with an analogue donor could provide more routes to higher-quality solar cells. (c) 2022 Science Press and Dalian Institute of Chemical Physics, Chinese Academy of Sciences All rights reserved.