Quantum Chemistry for Molecular Vibrational and Electronic Transitions at Organic Interfaces

Summary

The goal of this project is to obtain with the help of theory a detailed understanding of vibronically excited states of organic molecules at internal interfaces in order to identify general features and major processes that determine nature and behaviour of these states. The vision is to use this insight in the long run to design internal interfaces with desired properties. The focus is on the molecular and vibronic structure of extended π-systems at internal interfaces, the interface determined dynamics of excited states and the overall photophysical kinetics. Key component is the delicate interplay between local singly excited states (Frenkel excitons), charge transfer excited states (charge transfer excitons), interface induced formation of double excita-tions (biexciton formation) and vibrationally assisted transitions between these different electronic states (electron-phonon coupling).

Within this funding period, particular emphasis shall be placed on the theoretical description of interface dependent many-body correlation effects between organic systems. Besides electron correlation in particle-hole excited systems across the organic interface, we will describe the correlation induced formation of two-particle-two-hole excitations and the prediction of spectroscopic signatures thereof.

Project-related publications

1. R. Einholz, T. Fang, R. Berger, P. Grüninger, A. Früh, T. Chassé, R. F. Fink and H. Bettinger
   Heptacene: Characterization in Solution, in the Solid State, and in Films
   J. Am. Chem. Soc. 139, 4435 (2017).
2. A.-K. Hansmann, R. Berger
   Variation of the Fine-Structure Constant in Model Systems for Singlet Fission
   J. Phys. Chem. A 124, 6682 (2020).
3. A.-K. Hansmann, R. C. Döring, A. Rinn, S. M. Giesen, M. Fey, T. Breuer, R. Berger, G. Witte, S. Chatterjee
   Charge Transfer Excitation and Asymmetric Energy Transfer at the Interface of Pentacene-Perfluoropentacene Heterostacks
   Appl. Mater. Interfaces accepted article (2021).