Spectral Signatures of Perylene Diimide Derivatives: Insights From Theory

Perylene diimides and related compounds (naphthalene diimides, anthracene diimides, etc.) are one of the most important classes of organic dyes. Therefore, the prediction and the rationalization of both their transition energies and the particular shape of their absorption and emission spectra is essential to improve their design. Here, we report the simulations of both adiabatic and vibronic signatures of a series of perylene diimide derivatives with a state-of-the-art time-dependent density functional theory (TD-DFT) approach. First, the 0–0 energies have been computed and compared to experimental data. In a second stage, the determination of vibronic shapes has been performed to shed light on the vibrational modes implied in the experimental band topologies. Both anharmonicity and functionnal effects are also discussed. It turns out that theory consistently reproduced 0–0 energies but does not always yield band shapes in perfect match with experiment. In a last stage, new structures are designed, and it is shown that a full push effect is more effective than a push–pull strategy for the present class of molecules.