The van der Waals (vdW) interfaces of two-dimensional (2D) semiconductor are central to new device concepts and emerging technologies in light-electricity transduction where the efficient charge separation is a key factor. Contrary to general expectation, efficient electron–hole separation can occur in vertically stacked transition-metal dichalcogenide heterostructure bilayers through ultrafast charge transfer between the neighboring layers despite their weak vdW bonding. In this report, we show by ab initio nonadiabatic molecular dynamics calculations, that instead of direct tunneling, the ultrafast interlayer hole transfer is strongly promoted by an adiabatic mechanism through phonon excitation occurring on 20 fs, which is in good agreement with the experiment. The atomic level picture of the phonon-assisted ultrafast mechanism revealed in our study is valuable both for the fundamental understanding of ultrafast charge carrier dynamics at vdW heterointerfaces as well as for the design of novel quasi-2D devices for optoelectronic and photovoltaic applications.

中文翻译：

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范德华异质结构界面的声子辅助超快速电荷转移

二维（2D）半导体的范德华（vdW）接口对于光电转换中的新器件概念和新兴技术至关重要，其中高效电荷分离是关键因素。与一般预期相反，尽管相邻层之间的vdW键合较弱，但它们通过相邻层之间的超快速电荷转移，可以在垂直堆叠的过渡金属二卤化二异氰酸酯异质结构双层中发生有效的电子-空穴分离。在此报告中，我们从头开始显示非绝热分子动力学计算表明，绝热机理通过在20 fs内发生的声子激发来强烈促进超快层间空穴传输，而不是直接隧穿。在我们的研究中揭示的声子辅助超快机制的原子级图片，对于vdW异质界面上超快电荷载流子动力学的基本理解，以及对于光电和光伏应用的新型准2D器件的设计，都是有价值的。