Ternary solar cells with polymer donor and two nonfullerene acceptors

The third component has a strong effect on light absorption, energy level, and morphology of ternary blend film for all nonfullerene acceptors. Thus, the choice of the third component is required reasonably made. In this study, nonfullerene acceptor IT-2Cl and IT-4Cl are employed as the additional components to enhance PTB7-Th: 6TIC-4F based solar cells. IT-2Cl with a higher LUMO energy level could effectively elevate the voltages of ternary devices. IT-4Cl provides good complementary absorption to PTB7-Th and 6TIC-4F, which benefits for improving Jsc. In addition, both IT-2Cl and IT-4Cl improve the morphologies of the blends and thus help to enhance charge collection and transport of ternary devices. As a result, enhanced PCE values of 11.4% and 11.3% can be achieved for ternary solar cells with the addition of IT-2Cl and IT-4Cl, respectively. These results provide a guideline to select the third component for constructing high-efficiency ternary solar cells with two nonfullerenes.