Trap-Door-Like Irreversible Photoinduced Charge Transfer in a Donor–Acceptor Complex

Abstract

For efficient conversion of light into useful energy sources, it is very important to study and describe the first steps of primary charge-transfer process in natural structures and artificial devices. The time scale of these processes in artificial photosynthetic and photovoltaic devices is on the order of femto- to picoseconds and involves vibronic coupling of electrons and nuclei and also nuclear alleviation to enhance charge separation. Here we present an atomistic description of the photoexcited electron dynamics in a noncovalently bonded system formed by an hydrogenated nanodiamond as donor and a perylene diimide as an acceptor. The complex shows extremely fast charge transfer, separation, and stabilization within 90 fs. This stabilization is purely electronic in nature. To the best of our knowledge, these results show for the first time that it is possible to stabilize charge without polaron formation or nuclear relaxation, reaching a steady state enhanced by a pure electronic reorganization.

A Real-Time Time-Dependent Density Functional Tight-Binding Implementation for Semiclassical Excited State Electron–Nuclear Dynamics and Pump–Probe Spectroscopy Simulations

“…14 Here we show some preliminary simulations of the same system presented in ref. 68 (see figure 3a) including the nuclear motion using the Ehrenfest TD-DFTB method described in the section 2.…”

“…A strong decrease of the charge transferred when nuclear motion is allowed under the same ilummination conditions, supporting our previous hypothesis. 68 The effect of the nuclear motion on the charge transfer process can be interpreted as follows: the sudden nuclear motion increases the detuning, which allows the system to reach the steady-state regime sooner. This, in turn, reduces the total trans-ferred charge, since a new relaxation channel (i.e.…”

Ultrafast charge transfer and vibronic coupling in a laser-excited hybrid inorganic/organic interface

“…In the planar direction with respect to the molecule, the Si cluster is represented by a (4×3) supercell. The resulting system, containing 248 atoms in total, bears similarities with the hybrid interface formed by a hydrogenated diamond nanocluster doped by the perylenetetracarboxylic-acid-diimide molecule, which was previously considered to study ultrafast charge transfer with an atomistic computational approach [124].…”

Dynamical evolution of the Schottky barrier as a determinant contribution to electron–hole pair stabilization and photocatalysis of plasmon-induced hot carriers

“…It's important to state that this mechanism differs from the dynamical detuning of acceptor–donor states described in ref. 44. This dynamic contribution to the electron–hole stabilization has been overlooked and can be a missing piece in the complex puzzle that renders the hot carrier lifetime in nanosized structures.…”