The twist angle has weak influence on charge separation and strong influence on recombination in the MoS 2 /WS 2 bilayer: ab initio quantum dynamics
The twist angle has weak influence on charge separation and strong influence on recombination in the MoS 2 /WS 2 bilayer: ab initio quantum dynamics
复制标题
扭转角对 MoS 2 /WS 2 双层中的电荷分离影响较弱，但对复合影响较大：从头算量子动力学
DOI：
10.1039/d1ta10788g
复制
发表时间：
2022
影响因子：
11.9
通讯作者：
Prezhdo, Oleg V.
中科院分区：
文献类型：
--
作者：
Zhu, Yonghao;Fang, Wei-Hai;Rubio, Angel;Long, Run;Prezhdo, Oleg V.
二维过渡金属二硫属化合物的货车德瓦耳斯异质结在光电子学领域有着广泛的应用。层之间强的和可调节的相互作用可以影响控制材料性能的电荷和能量流。本文采用量子分子动力学从头算方法研究了双层扭曲角对MoS_2/WS_2异质结中电荷转移和复合的影响，包括高对称性的0°和60°结构，以及低对称性的9.43°和50.57°莫尔条纹结构.扭曲角调制层间耦合，证明了层间距离的变化，电子振动相互作用，并在平面外的振动频率的光谱位移。在飞秒时间尺度上，由于高的受主态密度和大的非绝热耦合，空穴传输对扭转角的依赖性很弱，并且是超快的。相比之下，电子-空穴复合需要几纳秒的时间，并且根据扭转角的不同而变化一个数量级。复合是缓慢的，因为它发生在一个大的能隙。这取决于扭转角，因为非绝热耦合是敏感的层间距离和重叠的电子和空穴波函数。莫尔图案系统表现出较弱的层间相互作用，产生较长寿命的电荷。电荷分离和复合都是由面外振动运动驱动的。模拟合理化的双层扭曲角的电荷分离和复合的影响的实验结果。原子论的观点为基于二维货车德瓦尔斯异质结构的高性能光电器件的设计提供了理论指导。
Van der Waals heterojunctions of two-dimensional transition-metal dichalcogenides are intensely investigated for multiple optoelectronics applications. Strong and adjustable interactions between layers can influence the charge and energy flow that govern material performance. We report ab initio quantum molecular dynamics investigation of the influence of the bilayer twist angle on charge transfer and recombination in MoS2/WS2 heterojunctions, including high-symmetry 0° and 60° configurations, and low symmetry 9.43° and 50.57° structures with Moiré patterns. The twist angle modulates interlayer coupling, as evidenced by changes in the interlayer distance, electron-vibrational interactions, and spectral shifts in the out-of-plane vibrational frequencies. Occurring on a femtosecond timescale, the hole transfer depends weakly on the twist angle and is ultrafast due to high density of acceptor states and large nonadiabatic coupling. In contrast, the electron–hole recombination takes nanoseconds and varies by an order of magnitude depending on the twist angle. The recombination is slow because it occurs across a large energy gap. It depends on the twist angle because the nonadiabatic coupling is sensitive to the interlayer distance and overlap of electron and hole wavefunctions. The Moiré pattern systems exhibit weaker interlayer interaction, generating longer-lived charges. Both charge separation and recombination are driven by out-of-plane vibrational motions. The simulations rationalize the experimental results on the influence of the bilayer twist angle on the charge separation and recombination. The atomistic insights provide theoretical guidance for design of high-performance optoelectronic devices based on 2D van der Waals heterostructures.