Dou Wenzhen, Jia Yizhen, Hao Xiamin, Meng Qingling, Wu Jinge, Zhai Shuwei, Li Tianzhao, Hu Weijuan, Song Biyu, Zhou Miao
School of Physics, Beihang University, Beijing 100191, China.
J Phys Chem Lett. 2021 Mar 18;12(10):2682-2690. doi: 10.1021/acs.jpclett.1c00455. Epub 2021 Mar 10.
Two-dimensional (2D) ReSe has attracted considerable interest due to its unique anisotropic mechanical, optical, and exitonic characteristics. Recent transient absorption experiments demonstrated a prolonged lifetime of photoexcited charge carriers by stacking ReSe with MoS, but the underlying mechanism remains elusive. Here, by combining time-domain density functional theory with nonadiabatic molecular dynamics, we investigate the electronic properties and charge carrier dynamics of 2D ReSe/MoS van der Waals (vdW) heterostructure. ReSe/MoS has a type II band alignment that exhibits spatially distinguished conduction and valence band edges, and a built-in electric field is formed due to interface charge transfer. Remarkably, in spite of the decreased band gap and increased decoherence time, we demonstrate that the photocarrier lifetime of ReSe/MoS is ∼5 times longer than that of ReSe, which originates from the greatly reduced nonadiabatic coupling that suppresses electron-hole recombination, perfectly explaining the experimental results. These findings not only provide physical insights into experiments but also shed light on future design and fabrication of functional optoelectronic devices based on 2D vdW heterostructures.
二维（2D）ReSe因其独特的各向异性机械、光学和激子特性而备受关注。最近的瞬态吸收实验表明，通过将ReSe与MoS堆叠，光激发电荷载流子的寿命得以延长，但其潜在机制仍不清楚。在此，通过将时域密度泛函理论与非绝热分子动力学相结合，我们研究了二维ReSe/MoS范德华（vdW）异质结构的电子特性和电荷载流子动力学。ReSe/MoS具有II型能带排列，表现出空间上不同的导带和价带边缘，并且由于界面电荷转移而形成了内建电场。值得注意的是，尽管带隙减小且退相干时间增加，但我们证明ReSe/MoS的光载流子寿命比ReSe长约5倍，这源于极大地减少了抑制电子-空穴复合的非绝热耦合，完美地解释了实验结果。这些发现不仅为实验提供了物理见解，也为基于二维vdW异质结构的功能性光电器件的未来设计和制造提供了启示。
