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O: Fachverband Oberflächenphysik

O 120: Focus Session: Nonequilibrium Electron Transfer Across Interfaces in Real Time

O 120.2: Vortrag

Freitag, 20. März 2020, 11:00–11:15, TRE Ma

Ultrafast charge transfer and vibronic coupling in donor/acceptor interfaces — •Matheus Jacobs, Jannis Krumland, Ana M. Valencia, and Caterina Cocchi — Institut für Physik und IRIS Adlershof, Humboldt-Universität zu Berlin, Germany

Donor-acceptor (DA) interfaces are ubiquitous in materials for optoelectronic applications and strongly characterize their intrinsic properties. Interfacial charge transfer, in particular, plays a crucial role in the electronic structure and optical response of these systems. For this reason, it is essential to gain insight on the fundamental processes involved at the interface also beyond the static picture. In the framework of real-time time-dependent density-functional theory coupled to Ehrenfest molecular dynamics, we investigate the microscopic mechanisms driving ultrafast charge transfer at DA interfaces. Specifically, we address the role of vibronic coupling in systems perturbed by an external laser pulse. For this purpose, we consider prototypical inorganic/organic and all-organic interfaces formed by the acceptor 2,3,5,6- tetrafluoro-7,7,8,8-tetracyano-quinodimethane (F4TCNQ) by doping a hydrogenated silicon cluster and an oligothiophene molecule. From the analysis of charge distribution across the interface, of the induced electron density, and of the bond length dynamics, we demonstrate that the nature and amount of charge transfer results from a complex interplay between coupled electronic and vibrational degrees of freedom, which is crucially dependent on the material composition.