Yu Sheng, Rice Quinton, Neupane Tikaram, Tabibi Bagher, Li Qiliang, Seo Felix Jaetae
Advanced Center for Laser Science and Spectroscopy, Department of Physics, Hampton University, Hampton, VA 23668, USA.
Phys Chem Chem Phys. 2017 Sep 13;19(35):24271-24275. doi: 10.1039/c7cp04385f.
Piezoelectricity appears in the inversion asymmetric crystal that converts mechanical deformation to electricity. Two-dimensional transition metal dichalcolgenide (TMDC) monolayers exhibit the piezoelectric effect due to inversion asymmetry. The intrinsic piezoelectric coefficient (e) of MoS is ∼298 pC m. For the single atomic shift of Mo of 20% along the armchair direction, the piezoelectric coefficient (e) of MoS with 5 × 5 unit cells was enhanced up to 18%, and significantly modified the band structure. The single atomic shift in the MoS monolayer also induced new energy levels inside the forbidden bandgap. The defect-induced energy levels for a Mo atom shift along the armchair direction are relatively deeper than that for a S atom shift along the same direction. This indicates that the piezoelectricity and band structure of MoS can be engineered by a single atomic shift in the monolayer with multi unit cells for piezo- and opto-electric applications.
压电性出现在将机械变形转化为电能的反演不对称晶体中。二维过渡金属二硫属化物（TMDC）单层由于反演不对称而表现出压电效应。MoS的本征压电系数（e）约为298 pC/m。对于Mo沿扶手椅方向单原子位移20%的情况，具有5×5晶胞的MoS的压电系数（e）提高了18%，并显著改变了能带结构。MoS单层中的单原子位移还在禁带内诱导出了新的能级。沿扶手椅方向Mo原子位移引起的缺陷诱导能级比沿相同方向S原子位移引起的缺陷诱导能级相对更深。这表明，对于压电和光电应用，可以通过具有多个晶胞的单层中的单原子位移来设计MoS的压电性和能带结构。
