Vibronic quantized tunneling controlled photoinduced electron transfer in an organic solar cell subjected to an external electric field

Abstract

In this work, vibration-resolved photoinduced electron transfer of an organic conjugated D⋯A system subjected to an external electric field was theoretically investigated. The ground and excited state vibrational relaxation energies were quantitatively characterized. The effective high frequency, ω^eff, could be estimated from the variation in energy of the excited-state equilibrium geometries of acceptor and donor sites as well as the analysis of the vibrational modes upon electron transfer. For a PCDTBT:PC₇₀BM blend in an external electric field, the vibronic modes affected the charge separation process differently from the charge recombination process. The simulated results indicated that the vibrational quantum tunneling effect facilitated the charge recombination process to a large extent. Thus, for electron transfer reactions, considering the vibrational excitation influence and perturbed nucleus–electron interactions is essential. These results provide a feasible way to enhance the efficiency in yielding the electron transfer process products.