Zhang Kunyan, Guo Yunfan, Ji Qingqing, Lu Ang-Yu, Su Cong, Wang Hua, Puretzky Alexander A, Geohegan David B, Qian Xiaofeng, Fang Shiang, Kaxiras Efthimios, Kong Jing, Huang Shengxi
Department of Electrical Engineering, The Pennsylvania State University, University Park, Pennsylvania 16802, United States.
Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States.
J Am Chem Soc. 2020 Oct 14;142(41):17499-17507. doi: 10.1021/jacs.0c07051. Epub 2020 Oct 2.
Interlayer coupling plays essential roles in the quantum transport, polaritonic, and electrochemical properties of stacked van der Waals (vdW) materials. In this work, we report the unconventional interlayer coupling in vdW heterostructures (HSs) by utilizing an emerging 2D material, Janus transition metal dichalcogenides (TMDs). In contrast to conventional TMDs, monolayer Janus TMDs have two different chalcogen layers sandwiching the transition metal and thus exhibit broken mirror symmetry and an intrinsic vertical dipole moment. Such a broken symmetry is found to strongly enhance the vdW interlayer coupling by as much as 13.2% when forming MoSSe/MoS HS as compared to the pristine MoS counterparts. Our noncontact ultralow-frequency Raman probe, linear chain model, and density functional theory calculations confirm the enhancement and reveal the origins as charge redistribution in Janus MoSSe and reduced interlayer distance. Our results uncover the potential of tuning interlayer coupling strength through Janus heterostacking.
层间耦合在堆叠范德华（vdW）材料的量子输运、极化子和电化学性质中起着至关重要的作用。在这项工作中，我们通过利用一种新兴的二维材料——Janus过渡金属二硫属化物（TMDs），报道了vdW异质结构（HSs）中非常规的层间耦合。与传统的TMDs相比，单层Janus TMDs有两个不同的硫属元素层夹着过渡金属，因此呈现出镜面对称性破缺和固有垂直偶极矩。当形成MoSSe/MoS HS时，与原始的MoS对应物相比，发现这种对称性破缺能将vdW层间耦合强烈增强多达13.2%。我们的非接触超低频拉曼探针、线性链模型和密度泛函理论计算证实了这种增强，并揭示其起源是Janus MoSSe中的电荷重新分布和层间距离减小。我们的结果揭示了通过Janus异质堆叠调节层间耦合强度的潜力。
