Fullerene-free polymer solar cells have received increasing attention

because the non-fullerene acceptors offer a great chance to achieve complementary absorption and appropriate molecular orbitals to the polymer donor materials

which may result in much improved performance of the resulting devices.Recently

a new record of power conversion efficiency of 11.2% has been set based on a non-fullerene electron-accepting material and a medium-bandgap conjugated polymer.This result indicates that the development of new non-fullerene electron-accepting materials and their applications in polymer solar cells would be a next hot spot of the research field

which may be the breakthrough point of this technology.