Donor−Acceptor Distance-Dependent Charge Transfer Dynamics Controlled by Metamaterial Structures
Kwang Jin Lee, Yiming Xiao, Eun Sun Kim, Fabrice Mathevet, Loic Mager, Olivier Cregut, Frédéric Fages, Jean-Charles Ribierre, Jeong Weon Wu, Anthony D’Aléo
ACS Photonics 6, 11, 2649-2654 (2019)
The capability to control charge transfer dynamics in a donor–acceptor molecule is important for efficient optoelectronic devices. Charge transfer dynamics is governed by thermodynamics of donor–acceptor charges in a given dielectric environment. Metamaterial structure has been shown to be able to control charge separation and charge recombination processes via nonlocal effect on dielectric permittivity for a fixed donor–acceptor distance organic film. Here, we report the influence of the metamaterial structure on the donor–acceptor distance dependence of the electron transfer process occurring in liquid crystalline organic semiconductor thin films. By examining the charge recombination rate in three different donor–acceptor distances, it is found that the barrier height β increases from 0.084 to 0.137 Å–1 by 63% in the presence of metal-dielectric multilayered metamaterial structures. Based on the Marcus theory on the charge transfer process, we show that a further increase in the driving force for a larger donor–acceptor distance is mainly responsible for the barrier height increase in the presence of a multilayered metamaterial substrate when compared with a glass substrate. This study will provide a significant step forward in enabling more efficient hybrid organic-optoelectronic devices associated with the charge transfer process.