Compared with the blendsbased on fu

Compared with the blendsbased on fullerene acceptors, the EL comes from charge transferstate emission, which is red-shifted relative to the donor/acceptor singlet emission, the EL of the blends based on NFAs mainlycomes from the singlet excitons in the donor polymers [167],which means reducing the energy offset of the donor and acceptor can reduce the energy losses from both the radiative recombination and nonradiative recombination. Yan et al. [37] statedthat the fundamental mechanism of more effective charge generation in an organic blend without requiring a driving force andthe nonradiative recombination in OPVs on a molecular levelare still unclear. The macroscopic parameters of OPV blends thatinfluence energy losses should be taken into consideration, i.e.,the degree of donor–acceptor mixing and the interfacial energetic disorder, dielectric constant, charge transfer state lifetimeetc. [168]. The performance of non-fullerene-based OSCs couldbe improved through reducing energy losses by optimizing themacroscopic parameters of the interface between donor andacceptor through molecular design. F