The absorption spectra of PDI-F tetramer display the similar behaviours with those of PDI-CN. As shown in Table , when LE and CTE states are coupled, the absorption peaks in the high-energy region are primarily contributed by the eighth(23812 cm -1 ), nineth(23920 cm -1 ), and tenth (24009 cm -1 ) exciton states, with LE state components of 12.5%, 11.7%, and 14.2%, respectively. The low-energy absorption peaks are mainly contributed by the first and fourth exciton states. However, the ECD spectra exhibit characteristics completely opposite to those of PDI-CN. The strong coupling between LE and CTE states results in increased energy splitting of the exciton states, leading to the positive peak in the lowenergy region not being fully canceled out by the adjacent negative peak. Overall, new positive bands emerge in both the low-and high-energy range compared to the decoupled case.