Molecular Doping in the Organic Semiconductor Diindenoperylene: Insights from Many-Body Perturbation Theory

Molecular doping provides a route toward designing new organic compounds with improved performance for optoelectronics. Here, we investigate the p-type doping of crystalline diindenoperylene (DIP) with two recently proposed electron-accepting molecular dopants using many-body perturbation theory. For the pristine DIP crystal, the quasiparticle band structure and the optical absorption spectra are found in agreement with the experimental data. Using the same methodology, we then characterize the optical and electronic properties of the two doped DIP crystals. The bandgap of both doped crystals is narrowed considerably due to the formation of hybridized states at the valence band edge. Moreover, a hybrid unoccupied mid-gap band is created with a host-dopant charge-transfer characteristic, giving rise to broader absorption spectra and a much lower absorption onset as compared to pristine DIP. Our results highlight that the interaction and hybridization with the host environment, including many-body effects, must be carefully considered in order to identify appropriate molecular dopants for a given organic crystal.