It has been found that the two main absorption peaks in DPND6 and DPND aggregates at the energy lower 3.5 eV are attributed from the interplay between the FE and CT states. The remarkable differences in spectral shapes of the two aggregates come from the different energy gaps and couplings among LE and CT states, causing the different degree of mixing of LE and CT states. In DPND6, this two states only have an energy spacing of ∼ 0.1 eV and the low-energy state predominates the optical absorption. While the two states in DPND have an energy spacing of ∼ 0.6 eV and the high-energy absorption strength can even exceed the lowenergy one for the aggregates with more than 4 monomers. The vibrational progressions in the absorption spectra of two aggregates are not obvious, however, the lowest-energy absorption peak of DPND6 comes from the transition between the electronic ground state and the vibrational levels of electronic dark excited state. The exciton dynamics simulations demonstrate that the time scales of population exchange between LE and CT states are much faster in DPND aggregates than in DPND6 aggregates due to the stronger intermolecular interaction, which makes the DPND favorable for the use of CT state properties. However, it is difficult for the photoexcitation to directly generate the charge-separated states in both aggregates due to the lack of enough driving forces.