Tailoring of centric extent fullerene-free acceptors to improve photoelectric properties of organic solar cells: A computational approach

Abstract

Non-fullerene acceptors have attracted considerable interest due to their superior performance in organic solar cells compared to fullerene acceptors. Using density functional theory (DFT) and its time-dependent approach, the optoelectronic properties of designed molecules have been evaluated. The designed molecules have a low band gap of 2.046–2.072 eV, which is significantly lower than reference 2.080 eV. The designed molecules exhibit lower excitation energy in both gaseous (1.830–1.855 eV) and solvent states (1.711–1.738 eV) compared to R values of 1.871 eV (gaseous) and 1.751 eV (solvent). Low reorganizational energies of electron (λe = 0.0044–0.0052 eV) and proton (λh = 0.2285–0.2343 eV) has been achieved in all designed molecules compared to reference (λe = 0.3437 eV, λh = 0.2361 eV). The designed molecules showed an increase in open circuit voltage (Voc), ranging from 1.60 to 1.73 eV, compared to reference value 1.59 eV. In addition, a significant charge shift at the HOMO (PM6)-LUMO (BB3) interface was observed.