The structures of PDI-CN/PDI-F monomers shown in Figure and tetramers are extracted from the experimental crystal structure. In this work, two benzyl groups at the PDI amide positions are replaced with two methyl groups to save computational cost. The other reason for this substituent is that we focus on the spectral range around 400-600 nm, which is measured experimentally. In this range, the electronic excitation (S 1 state) mainly takes place on the PDI core (See Figure in SI), the benzyl groups attached to the nitrogen do not participate in the excitation, and the S 2 state with excitation energy of 3.7118 eV falls outside this energy range.