From 1995-2015, fullerene derivatives had been the dominating electron acceptors in organic solar cells (OSCs) owing to their performance superiority to other acceptors. However, the drawbacks of fullerenes, such as weak visible absorption, limited tunability of electronic properties and morphological instability, restrict further development of OSCs toward higher efficiencies and practical applications. Therefore, the development of new acceptors beyond fullerenes is urgent in the field of OSCs.
