The structural and optoelectronic properties of a novel ZnI₂/CdS van der Waals (vdW) heterostructure are studied under the effect of biaxial strain based on the density functional theory. Our results show that the ZnI₂/CdS vdW heterostructure is dynamically and thermally stable depending on the molecular dynamics simulation and phonon dispersion curve. The results also indicate that the ZnI₂/CdS heterostructure exhibits type-II band alignment with an indirect energy gap of 0.886 and 1.336 eV according to the Perdew–Burke–Ernzerhof and Heyd–Scuseria–Ernzerhof methods, respectively. Besides, the biaxial strain has a significant impact on the electronic properties. The energy bandgap of the ZnI₂/CdS heterostructure decreases gradually as the compressive strain increases, reaching a minimum value of 1.162 eV at −6%. Also, a transformation from indirect bandgap to direct bandgap appears at strains of 4% and 6%. Broadly, it has been found that the optical properties of the ZnI₂/CdS vdW heterostructure improve under the influence of strain, and the absorption coefficient can reach 10⁵ cm⁻¹ with the emergence of a shift phenomenon that expands the absorption capacity. Therefore, the application of strain will drastically improve the optical and electronic properties of the ZnI₂/CdS vdW heterostructure, providing a roadmap for enhancing optical efficiency in photocatalytic and photovoltaic devices.

中文翻译：

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通过光学纳米器件的双轴应变调整二维 ZnI2/CdS 异质结构的光学和电子特性：第一性原理研究

基于密度泛函理论，在双轴应变的影响下研究了新型 ZnI ₂ /CdS 范德华 (vdW) 异质结构的结构和光电特性。我们的结果表明，ZnI ₂ /CdS vdW 异质结构是动态和热稳定的，这取决于分子动力学模拟和声子色散曲线。结果还表明，根据 Perdew-Burke-Ernzerhof 和 Heyd-Scuseria-Ernzerhof 方法，ZnI ₂ /CdS 异质结构表现出 II 型能带排列，间接能隙为 0.886 和 1.336 eV。此外，双轴应变对电子特性有显着影响。ZnI ₂的能带隙/CdS 异质结构随着压缩应变的增加逐渐减小，在 -6% 时达到最小值 1.162 eV。此外，从间接带隙到直接带隙的转变出现在 4% 和 6% 的应变处。广泛地，已经发现ZnI ₂ /CdS vdW异质结构的光学性质在应变的影响下提高，并且吸收系数可以达到10 ⁵  cm ^-1并且出现扩大吸收容量的移位现象。因此，应变的应用将显着改善 ZnI ₂ /CdS vdW 异质结构的光学和电子特性，为提高光催化和光伏器件的光学效率提供路线图。