<br>由真正的一维范德华 Nb2Se9 材料制成的具有几乎直接带隙的无边缘缺陷各向异性二维片材。,ACS Omega

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由真正的一维范德华 Nb2Se9 材料制成的具有几乎直接带隙的无边缘缺陷各向异性二维片材。
ACS Omega ( IF 3.7 ) Pub Date : 2020-05-06 , DOI: 10.1021/acsomega.0c00388
Weon-Gyu Lee ₁ , You Kyoung Chung ₁ , Junho Lee ₁ , Bum Jun Kim ₂ , Sudong Chae ₃ , Byung Joo Jeong ₃ , Jae-Young Choi _{2,

3} , Joonsuk Huh _{1,

2}

Affiliation

无悬挂键二维 (2D) 材料可以从一维 (1D) 范德华材料的块体结构中分离出来，以生产无边缘缺陷的 2D 材料。传统的二维材料的边缘有悬挂键，它们充当散射中心，降低载流子的传输性能。由1D范德华Nb ₂ Se ₉材料制成的高度各向异性2D片材具有三种平面结构，具体取决于块体Nb ₂ Se ₉晶体的切割方向。为了研究这些2D Nb ₂ Se ₉片材的应用，我们计算了三个平面片材的能带结构，并观察到两个片材具有几乎直接带隙，仅比间接带隙稍大（0.01 eV）。这些能量差小于室温下的热能。具有间接带隙的2D Nb ₂ Se ₉平面在三个平面中具有最短的硒离子链间距离，并且在导带上表现出显着的链间相互作用。链间应变在 2D Nb ₂ Se ₉片层中引起了间接带隙到直接带隙的转变。由于链之间不同的相互作用，这些具有直接带隙的 Nb ₂ Se ₉二维片也具有不同的能带结构，这意味着它们可以具有不同的电荷迁移率。我们期望这些无悬挂键的 2D Nb ₂ Se ₉片材能够应用于光电器件，因为它们允许几乎直接的带隙。它们还可以用于机械传感器，因为带隙可以通过改变链间应变来控制。

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Edge Defect-Free Anisotropic Two-Dimensional Sheets with Nearly Direct Band Gaps from a True One-Dimensional Van der Waals Nb2Se9 Material.

Dangling-bond-free two-dimensional (2D) materials can be isolated from the bulk structures of one-dimensional (1D) van der Waals materials to produce edge-defect-free 2D materials. Conventional 2D materials have dangling bonds on their edges, which act as scattering centers that deteriorate the transport properties of carriers. Highly anisotropic 2D sheets, made of 1D van der Waals Nb₂Se₉ material, have three planar structures depending on the cutting direction of the bulk Nb₂Se₉ crystal. To investigate the applications of these 2D Nb₂Se₉ sheets, we calculated the band structures of the three planar sheets and observed that two sheets had nearly direct band gaps, which were only slightly greater (0.01 eV) than the indirect band gaps. These energy differences were smaller than the thermal energy at room temperature. The 2D Nb₂Se₉ plane with an indirect band gap had the shortest interchain distance for selenium ions among the three planes and exhibited significant interchain interactions on the conduction band. The interchain strain induced an indirect-to-direct band gap transition in the 2D Nb₂Se₉ sheets. These 2D sheets of Nb₂Se₉ with direct band gaps also had different band structures because of different interactions between chains, implying that they can have different charge mobilities. We expect these dangling-bond-free 2D Nb₂Se₉ sheets to be applied in optoelectronic devices because they allow for nearly direct band gaps. They can also be used in mechanical sensors because the band gaps can be controlled by varying the interchain strain.

更新日期：2020-05-06

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