Figure : The normalized electronic absorption and ECD spectra of PDI-CN aggregates calculated by TD-DFT method varied with the aggregate sizes (i.e. the spectral intensities are divided by the number of PDI units). The gray dashed line (20967 cm -1 ) denotes the lowest excitation energy of the monomer. Gaussian lineshape with FWHM of 806 cm -1 was employed. Plots show all states with energies less than 26000 cm -1 .