The methyl-substituted PDI-F/PDI-CN tetramers are composed of 184/188 atoms, re-spectively. Their excited electronic states are calculated at theoretical level of TDDFT/6-31G(d) with the Coulomb-attenuated hybrid XC functional CAM-B3LYP. To mimic the experimental environment, the SMD implicit solvation model 75 is adopted to account for the mixed solvent effect. All QM calculations were finished within the Gaussian 16 package. 76