TMDCs vdW异质结构层间激子效应

二维TMDCs vdW异质结构是光–电相互转化概念和技术的基础，在光伏、太阳能电池、光探测器件、发光二极管和光捕获等方面具有巨大的应用潜力。这类结构中的层间激子效应是决定其材料性质和应用的关键，然而关于该课题的主要研究进展仍处于实验观测阶段，层间激子行为特征的理论研究还鲜有报道。本申请拟采用格林函数多体微扰理论研究二维TMDCs vdW异质结构光学吸收性质，激子波函数空间分布特征和激子半径、激发能、结合能、寿命等。分析动量和能量守恒过程、暗激子和热激子产生机制及其对激子寿命的影响等，阐明层间激子效应及其微观机制。研究电子–声子耦合作用对光学吸收性质的影响，进一步分析电子、光子、声子之间的作用对层间激子效应的影响。研究结果将对正确理解二维TMDCs vdW异质结构这一新的材料体系的独特性质和促进其在光–电相互转化领域的应用具有重要意义。

Two-dimensional (2D) van der Waals (vdW) heterostructures of transition metal dichalcogenides (TMDCs) are the central to the concepts and emerging technologies of light–electricity interconversion, holding great promise in photovoltaics, solar cells, photodetectors, light–emitting diodes and light harvesting. It should be pointed out that the interlayer excitonic effects are the key to determine the novel material properties and the practical applications. However, study on the properties of interlayer excitonic behavior mainly lies in experiments, theoretical study is still in urgent need. In this proposal, we will study the optical absorption properties of 2D TMDCs vdW heterostructures by means of Green’s function many–body perturbation theory, giving rise to the distribution of exciton wave function in real space, the radius, excitation energy, binding energy and life–time of excitons. On the basis of the results obtained, energy and momentum conservation, formation of dark and hot exciton and their effects on the exciton life–time will be investigated, unraveling the interlayer excitonic effects and the mechanism at atomic scale. The effects of electron–phonon coupling on the optical absorption will be revealed, and the effects of the interactions between electron, photon and phonon on the interlayer excitonic effects will be discussed. Our results will significantly advance the understanding on the novel properties and greatly promote the applications in light–electricity interconversion of 2D TMDCs vdW heterostructures.