title: Coherent Dynamics of Mixed Frenkel and Charge-Transfer Excitons in Dinaphtho[2,3-b:2'3'-f]thieno[3,2-b]-thiophene Thin Films: The Importance of Hole Delocalization.
abstract: Charge-transfer states in organic semiconductors play crucial roles in processes such as singlet fission and exciton dissociation at donor/acceptor interfaces. Recently, a time-resolved spectroscopy study of dinaphtho[2,3-b:2'3'-f]thieno[3,2-b]-thiophene (DNTT) thin films provided evidence for the formation of mixed Frenkel and charge-transfer excitons after the photoexcitation. Here, we investigate optical properties and excitation dynamics of the DNTT thin films by combining ab initio calculations and a stochastic Schrödinger equation. Our theory predicts that the low-energy Frenkel exciton band consists of 8-47% CT character. The quantum dynamics simulations show coherent dynamics of Frenkel and CT states in 50 fs after the optical excitation. We demonstrate the role of charge delocalization and localization in the mixing of CT states with Frenkel excitons as well as the role of their decoherence.
authors.affiliation: Department of Chemistry, Graduate School of Science, Kyoto University , Kyoto 606-8502, Japan.
authors.forename: Takatoshi
authors.initials: T
authors.lastname: Fujita
authors.affiliation: TOBB University of Economics and Technology , Sogutozu, Ankara 06560, Turkey.
authors.forename: Sule
authors.initials: S
authors.lastname: Atahan-Evrenk
authors.affiliation: Department of Chemistry and Chemical Biology, Harvard University , Cambridge, Massachusetts 02138, United States.
authors.forename: Nicolas P D
authors.initials: NP
authors.lastname: Sawaya
authors.affiliation: Department of Chemistry and Chemical Biology, Harvard University , Cambridge, Massachusetts 02138, United States.
authors.forename: Alán
authors.initials: A
authors.lastname: Aspuru-Guzik
mesh_terms: D004583:Electrons; D008027:Light; D008958:Models, Molecular; D055668:Photochemical Processes; D011789:Quantum Theory; D012666:Semiconductors; D013876:Thiophenes / Q000737:chemistry*
chemical_list: D013876:Thiophenes