In this paper, Cu₂ZnSn(S_xSe_1−x)₄(CZTSSe) thin-films with a front-graded band gap were prepared by plasma sulfurization. The method of selenization followed by low-temperature plasma sulfurization was adopted to effectively control the uneven diffusion of S in the absorption layer. By investigating and analyzing the grazing incidence X-ray diffraction, Raman spectroscopy, and PL spectra, the CZTSSe absorption layer with an S-rich top and S-poor bottom layer could be obtained by plasma sulfurization. The inhomogeneous distribution of S led to the formation of band gap gradients. Based on that, the band gap near the top of the absorption layer was determined to be 1.13 eV and the bottom band gap was 1.03 eV. Approximately 300 nm thick sulfur-rich CZTSSe films were found near the surface favoring an increase in the band gap at the interface, which could be attributed to a high open circuit voltage (V_oc). The establishment of the band gap gradient formed a barrier towards the motion of holes towards the interface and increased the effective interfacial recombination band gap, both of which significantly reduced the interfacial recombination. Finally, the CZTSSe thin-film solar cells with a band gap gradient were prepared by plasma sulfurization exhibited a power conversion efficiency (PCE) of 8.11%. Compared with CZTSSe thin-film solar cells without post plasma sulfurization, which had a PCE of 6.98%, the V_oc of the CZTSSe solar cell improved considerably from 471.37 mV to 513.93 mV; however, it had little effect on short-circuit current density (J_sc).

在本文中，Cu ₂ ZnSn(S _x Se _{1− x} ) ₄通过等离子体硫化制备具有前梯度带隙的 (CZTSSe) 薄膜。采用先硒化后低温等离子硫化的方法，有效控制了S在吸收层中的不均匀扩散。通过对掠入射 X 射线衍射、拉曼光谱和 PL 光谱的研究和分析，可以通过等离子体硫化获得具有富硫顶层和贫硫底层的 CZTSSe 吸收层。S 的不均匀分布导致带隙梯度的形成。基于此，确定吸收层顶部附近的带隙为 1.13 eV，底部带隙为 1.03 eV。在表面附近发现了大约 300 nm 厚的富含硫的 CZTSSe 膜，有利于增加界面处的带隙，_哦）。带隙梯度的建立对空穴向界面的运动形成了障碍，并增加了有效的界面复合带隙，这两者都显着降低了界面复合。最后，通过等离子体硫化制备具有带隙梯度的 CZTSSe 薄膜太阳能电池，其功率转换效率 (PCE) 为 8.11%。与没有后等离子体硫化的CZTSSe薄膜太阳能电池相比，PCE为6.98%，CZTSSe太阳能电池的V _oc从471.37 mV大幅提高到513.93 mV；然而，它对短路电流密度（J _sc）几乎没有影响。