Excited-State Dynamics in Perylene-Based Organic Semiconductor Thin Films: Theory Meets Experiment

Abstract

Perylene-based organic semiconductors are widely used in organic electronic devices. Here, we studied the ultrafast excited-state dynamics in diindenoperylene (DIP) and dicyanoperylene-bis(dicarboximide) (PDIR-CN2) thin films, respectively, after optical excitation using femtosecond (fs) time-resolved second harmonic generation in combination with large scale quantum chemical calculations. In DIP, the initial optical excitation leads to the formation of delocalized excitons, which localize on dimers on a ultrafast time scale of <50–150 fs depending on the excitation energy. In contrast, in PDIR-CN2, the optical excitation directly generates localized excitons on monomers or dimers. In both DIP and PDIR-CN2, localized excitons decay within hundreds of fs into Frenkel-like trap sites. The relaxation to the ground state occurs in DIP on a time scale of 600 ± 110 ps. In PDIR-CN2, this relaxation time is 1 order of magnitude faster (62 ± 1.8 ps). The differences in the exciton formation and decay dynamics in D...