Phonon-Assisted Ultrafast Charge Transfer at van der Waals Heterostructure Interface
Phonon-Assisted Ultrafast Charge Transfer at van der Waals Heterostructure Interface
复制标题
范德华异质结构界面声子辅助超快电荷转移
DOI：
10.1021/acs.nanolett.7b03429
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发表时间：
2017
期刊：
影响因子：
10.8
通讯作者：
Zhao Jin
中科院分区：
文献类型：
--
作者：
Zheng Qijing;Saidi Wissam A.;Xie Yu;Lan Zhenggang;Prezhdo Oleg V.;Petek Hrvoje;Zhao Jin
二维(2D)半导体的范德华(VDW)界面是光电转换新器件概念和新兴技术的核心，其中有效的电荷分离是关键因素。与一般的预期相反，在垂直堆积的过渡金属二卤化物异质结构双层中，尽管它们的VDW键很弱，但通过相邻层之间的超快电荷转移可以实现有效的电子-空穴分离。在本文中，我们用从头算非绝热分子动力学计算表明，超快空穴转移不是直接隧穿，而是通过声子激发的绝热机制强烈地促进了层间空穴的转移，这与实验符合得很好。我们的研究揭示了声子辅助的超快机制的原子级图像，这对于深入理解VDW异质界面的超快载流子动力学以及设计用于光电子学和光伏应用的新型准2D器件都是有价值的。
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 byab initiononadiabatic 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.