Vibrational and Electronic Spectroscopies of Dibenzoterrylene Conformers: Computational Insights

Dibenzoterrylene (DBT) is a coherent molecular single-photon emitter that exhibits an interesting energetic landscape with multiple low-energy, accessible conformations. In this work, using first principle approaches, we systematically investigate the conformational landscape of DBT in the gas phase, identifying five unique conformers, four of which are expected to be thermally accessible in a solid state host. We further analyze vibrational and electronic spectroscopies to identify conformer-specific spectral signatures. We find that each conformer exhibits largely similar spectral features in both vibrational and electronic spectroscopies; however, subtle differences exist across all spectra, which highlight possible conformer-specific changes that may be able to be identified in high-resolution spectroscopic experiments. Finally, we explore the Franck-Condon-Herzberg-Teller vibrationally resolved electronic excitation spectrum which showcases even more rich conformation-specific landmarks. Collectively, our results provide a comprehensive framework for understanding how DBT's conformer-specific electronic structure could play a role in observed optical behaviors.