Achieving high-performance ternary organic solar cells by adding a high hole-mobility non-fullerene acceptor

The addition of a functional third component in PM6:Y6 system has demonstrated great potential in achieving highly power conversion efficiency (PCE) for organic solar cells (OSCs). However, photocurrent generation is still limited by slow hole transfer from Y6 to PM6. Herein, a non-fullerene acceptor BTP-eC9, with high hole-mobility property, is incorporated into the PM6:Y6 blend to construct a ternary system. The good compatibility of acceptors with similar chemical structure is conducive to simultaneously fine-tune the morphology, energy level and spectra absorption. Moreover, the introduction of BTP-eC9 endows the active layer with high hole mobility and balanced electron and hole transfer, further achieving the increased short-circuit current density (JSC) and fill factor (FF). The optimized ternary OSCs give an improved PCE of 16.39%, which makes a significant enhancement compared to binary devices based on PM6:Y6 and PM6:BTP-eC9 (14.87% and 13.27%, respectively).