character gradually increases. The same trend was observed for the PC113-X series. For all the C22-X dimers, the portion of the |C22 0 X / ⟩ CT state is considerably higher than that of |C22 / X 0 ⟩, but the two CT states' portions are similar in the PC113-X series. As we mentioned in Section IV B, this substantial difference arises from C22's sp2 nitrogen which lowers the energy of |C22 0 X / ⟩ and increases its proportion. There are a few dimers, such as the C22-C91 dimer, with extremely large CT partitions, which can be attributed to the low-energy CT state |C22 0 X / ⟩ (E +, +T1→+44 = 1.64 eV) acting as the lowest diabatic state. A similar trend of LE & CT partition versus the E 5% of monomer X is still observed in the C22-X and PC113-X series with the TDM-perpendicular stacking (Figure ). Therefore, regardless of stacking configurations, the diabatic state with lower energy accounts for a larger proportion in dimer S1, making the excitons mainly localized on the monomer with lower E 5% .