Quinoxaline-based non-fullerene guest acceptor enables ternary organic solar cells achieving 18.9% efficiency via reducing energy loss and regulating morphology

Designing appropriate third component is considered as a valid and facile approach to improve the devices photovoltaic performance of organic solar cells. Here, a novel quinoxaline central core based non-fullerene acceptor named BQ was successfully synthesized. The excellent electron-withdrawing capacity of quinoxaline core enables BQ to possess an obviously upshift lowest unoccupied molecular orbital energy level, resulting in an extremely high open-circuit voltage (VOC) of 0.959 V when blended with polymer donor D18. When incorporating BQ as the guest acceptor to prepare ternary organic solar cells (TOSCs) in D18:N3 host system, an improved VOC of 0.846 V with reduced non-radiative recombination energy loss of 0.236 eV and an excellent fill factor of 79.95% were obtained. Encouragingly, the cascade-like model TOSCs achieved an excellent power conversion efficiency of 18.9%, which could attribute to the complementary absorption, fast exciton diffusion and dissociation, efficient carries transport and collection, appropriate phase separation and the lowest energy loss. This work demonstrates that incorporating a quinoxaline-based guest acceptor is a feasible strategy to achieve high-performance TOSCs.