We present a theoretical investigation of exciton-mediated Förster resonant energy transfers (FRET’s) from photoexcited quantum dots (QD’s) to transition-metal dichalcogenide monolayers (TMD-ML’s), implemented by the quantum theory of FRET on the base of first-principles-calculated exciton fine structures. With the enhanced electron-hole Coulomb interactions, atomically thin TMD-MLs are shown to serve as an exceptional platform for FRET that are mediated purely by excitons and take full advantage of the superior excitonic properties. Remarkably, the energy-transfer responses of atomically thin TMD-ML’s are shown to be dictated by the momentum-forbidden dark excitons rather than the commonly recognized bright ones. Specifically, the longitudinal dark exciton states following the exchange-driven light-like linear band dispersion play a key role in grading up the efficiency and robustness of FRET of TMD-ML against the inhomogeneity of QD-donor ensembles. With the essential involvement of dark excitons, the FRET responses of TMD-ML’s no longer follow the distance power law as classically predicted and, notably, cannot manifest the dimensionality of the donor-acceptor system.

我们对激子介导的福斯特共振能量转移 (FRET) 从光激发量子点 (QD) 到过渡金属二硫族化物单层 (TMD-ML) 进行了理论研究，这是通过基于第一原理的 FRET 量子理论实现的：计算的激子精细结构。随着电子-空穴库仑相互作用的增强，原子级薄的TMD-ML被证明可以作为FRET的特殊平台，其纯粹由激子介导，并充分利用优异的激子特性。值得注意的是，原子薄 TMD-ML 的能量转移响应被证明是由动量禁止的暗激子决定的，而不是通常公认的亮激子。具体来说，交换驱动的类光线性带色散之后的纵向暗激子态在提高 TMD-ML FRET 的效率和鲁棒性以应对 QD 供体系综的不均匀性方面发挥着关键作用。由于暗激子的重要参与，TMD-ML 的 FRET 响应不再遵循经典预测的距离幂律，尤其是不能体现供体-受体系统的维度。