$ MoX_{2}/MgPSe_{3}(X=S,Se) $ 电子结构与光学性能的理论研究

文章采用密度泛函理论方法，研究二维 $ MoX_{2}/MgPSe_{3} $ (X=S, Se) 异质结的电子结构和光学性能。能带结构和态密度分析发现， $ MoSe_{2}/MgPSe_{3} $ 和 $ MoSSe/MgPSe_{3} $ Ⅱ具有显著的Ⅱ型能带结构，并且该异质结的导带底（conduction band minimum，CBM）和价带顶（valence band maximum，VBM）分别在水的氧化还原电势（-4.44、-5.67 eV）两侧，该能带结构有利于该材料在光催化析氢方面的应用。通过对 $ MoX_{2}/MgPSe_{3} $ 施加均一的双轴应力，发现双轴应变对 $ MoX_{2}/MgPSe_{3} $ 的带隙有明显的线性调控作用，线性调控作用在压变传感方面有应用价值。光吸收系数的计算发现， $ MoSSe/MgPSe_{3} $ 在紫外光区域的吸收强度相比较单独的 $ MgPSe_{3} $ 和 $ MoX_{2} $ 有显著的提高，说明异质结对于改善材料的光学性能具有重要作用。

The electronic structure and optical property of 2D $ MoX_{2}/MgPSe_{3} $ (X=S, Se) is studied by density functional theory. The analysis of energy band structures and density of states indicates that $ MoSe_{2}/MgPSe_{3} $ and $ MoSSe/MgPSe_{3} $ II heterostructures have significant type-II band, and the conduction band minimum (CBM) and valence band maximum (VBM) of heterostructure are on both sides of the redox potentials of water (-4.44, -5.67 eV) respectively. This energy band structure is conducive to the application of the material in photocatalytic water splitting into hydrogen and oxygen. By applying uniform biaxial stress to $ MoX_{2}/MgPSe_{3} $, it is found that biaxial strain has an obvious linear regulating effect on the band gap of $ MoX_{2}/MgPSe_{3} $, and this linear regulating effect has application value in pressure transducers. The calculation of the light absorption coefficient finds that the absorption intensity of $ MoSSe/MgPSe_{3} $ in the ultraviolet region is significantly higher than that of $ MgPSe_{3} $ and $ MoX_{2} $ alone, indicating that heterostructures play an important role in improving the optical property of the material.