Energy and charge transfer dynamics at an organic donor/acceptor interface

Abstract Competition between the energy and charge transfer dynamics plays a crucial role in different photoelectric applications of organic donor/acceptor (D/A) interfaces, while its microscopic quantum dynamics and the quantitative correlation with the interface structure remain unclear. Here, by theoretically constructing an organic D/A interface with the donor initially photo-excited, we give a full consideration to this issue. Firstly, we investigate the effect of the interface electronic structure on the dynamics, which is modulated by tuning the on-site energy of donor. The results show that there exists a critical value of the on-site energy, below which energy transfer is dominant, otherwise charge transfer is dominant. Especially, when the on-site energy reaches up to a certain strength, the transferred electron into acceptor will experience an ultrafast internal conversion process. Furthermore, by separately choosing three typical electronic structures, we demonstrate the effect of the interface spatial structure on the dynamics. It is found that there exists an optimal spatial structure in either the energy transfer dominant interface or the charge transfer dominant interface, making the transfer efficiency to be the highest. These findings provide a microscopic understanding of how to optimize the interface structure to modulate the energy and charge transfer dynamics in different applications of organic D/A interfaces.