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硒化锑（Sb2Se3）是一种物相简单、元素丰富、经济友好的太阳电池吸收层材料，具有广阔的应用前景。然而，Sb2Se3较弱的导电性成为了限制电池器件性能的重要因素。迁移率是材料与器件的重要电学参数，应变可以改变载流子迁移率，因此，研究应变对Sb2Se3的载流子迁移率特性影响具有实际意义。本文通过密度泛函理论和形变势理论，系统研究了单轴应变对Sb2Se3能带结构、禁带宽度、等能面、有效质量的影响，分析了沿着x、y、z方向的三种单轴应变对载流子沿着x、y、z方向的迁移率影响。研究发现，对于无应变的Sb2Se3，μx远大于μy和μz，实验上应该将x方向作为Sb2Se3的特定生长方向（即内建电场方向）。综合应变对带隙、等能面、分态密度及迁移率的影响，本研究认为当应变沿着y轴方向，且压应变为3%的时候，能获得最佳性能的Sb2Se3太阳电池吸收层材料。Antimony selenide (Sb2Se3) is of simple-phase, element-rich, and economically friendly material for solar cell absorption layers with broad application prospects. However, the weak conductivity of Sb2Se3 has become a significant factor limiting the performance of solar cell devices. Carrier mobility is an important electrical parameter for both materials and devices, and strain can alter carrier mobility. Therefore, studying the effect of strain on the carrier mobility of Sb2Se3 is of practical significance. In this paper, using density functional theory and deformation potential theory, we systematically investigated the influence of uniaxial strain on the band structure, bandgap width, iso-surface, and effective mass of Sb2Se3. We analyzed the effects of three types of uniaxial strain along the x, y, and z directions on the carrier mobility along the x, y, and z directions. The study found that under these strains, the valence band maximum (VBM) position of Sb2Se3 remained unchanged, and the bandgap decreased overall with increasing strain along the y and z directions, while it increased along the x direction. The variation in bandgap may be related to the coupling strength between the Sb-5p and Se-4p orbitals of the conduction band minimum (CBM). For fully relaxed Sb2Se3, its iso-surface exhibited a distorted cylindrical shape, with low dispersion along the z-axis and high dispersion along the x and y axes, where μx was greater than μy and μz, suggesting that the x direction should be considered as the specific growth direction for Sb2Se3 experimentally. When the strain was applied along the x and z directions, μx gradually increased with increasing strain, while it decreased when the strain was applied along the y direction. Taking into account the combined effects of strain on bandgap, iso-surface, density of states, and mobility, this study suggests that the optimal performance of Sb2Se3 solar cell absorber layer material could be achieved when the strain was applied along the y-axis, with a compressive strain of 3%。
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Keywords:
- Sb2Se3 /
- mobility /
- deformation potential /
- strain engineering
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