New structures made based on Cu₂ZnSnS₄ (CZTS) by substitutions with Cr, Ti, V, and Mo species were investigated via density functional theory. The total substitution of Zn by Cr and V leads to the vanishing of the bandgap, while n-type conductivity with a low bandgap of 0.19 eV was predicted in the case Ti. In addition, the conduction band minimum and valence band maximum overlapping were observed for the Mo/Sn ratio of 1/3. Therefore, our study suggests that even the low content of alternative cations in CZTS allows to control its band alignment. The obtained results can be helpful for designing CZTS-based intermediate layers to improve the quality of the back interface of the CZTS thin-film solar cells.

中文翻译：

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DFT研究：各种掺杂元素对Cu2ZnSnS4（CZTS）薄膜电子结构的影响

通过密度泛函理论研究了基于Cu ₂ ZnSnS ₄（CZTS）替代Cr，Ti，V和Mo物种的新结构。用Cr和V完全取代Zn会导致带隙消失，而在Ti的情况下，n型电导率的低带隙为0.19 eV。另外，对于Mo / Sn比为1/3，观察到导带最小和价带最大重叠。因此，我们的研究表明，即使CZTS中替代阳离子的含量较低，也可以控制其能带排列。获得的结果有助于设计基于CZTS的中间层，以提高CZTS薄膜太阳能电池背面的质量。