Donor-acceptor (DA) hybrid interfaces formed by inorganic semiconductors doped by organic molecules are intriguing materials that combine the best of the two worlds and yet exhibit new features that are not present in the individual constituents. As a prototypical system, we consider the DY hybrid interface formed by 2,3,5,6- tetrafluoro-7,7,8,8-tetracyano-quinodimethane (F4TCNQ) physisorbed on a hydrogenated silicon cluster. The considered interface is p-doped and presents charge transfer at the ground-state. We explore the microscopic mechanisms driving the ultrafast charge transfer in the excited state by means of real-time time-dependent density functional theory coupled to Ehrenfest molecular dynamics. We monitor the electron dynamics in the femtosecond time scale in the system perturbed by a resonant time-dependent electric field. Our results show that in the 100 femtosecond time-window, the charge transfer across in the interface is increased by the resonant laser but it is not further promoted by vibronic coupling. Molecular vibrations coupled to the dynamics of the electronic degrees of freedom give rise to an enhanced intramolecular charge transfer. Our results are discussed in the context of all-organic DA interface.

Ab initio simulation of ultrafast charge transfer and vibronic coupling in donor/acceptor hybrid interfaces

ACS Spring Meeting 2021

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