Compared with fullerene acceptor

non-fullerene acceptor possesses the advantages of strong absorptions and tunable energy levels

thus enabling the improvement of power conversion efficiencies (PCEs) for fullerene-free polymer solar cells (PSCs). This article summarizes the progresses in non-fullerene acceptors developed in our group

and mainly introduces two design strategies: one is to ultilize dihedral angle and steric hindrance to construct non-planar small molecule acceptors

the other is to use intramolecular non-covalent interactions to construct planar small molecule acceptors. Both strategies are employed to address the following key challenges: to settle the dilemma between the formation of proper nanoscale phase separation and effective π-π stacking of non-fullerene molecules; to have the features of easy-synthesis and excellent morphological stability. Finally

we outline a perspective on the future development of non-fullerene acceptors.