Cu₂ZnSn(S,Se)S₄ (CZTSSe) thin films have attracted attention as low-cost absorber materials for solar cells; however, further studies are required to develop flexible solar cells from this material and to achieve a high power conversion efficiency. Toward this objective, this work investigated eight types of precursors applied on flexible Mo foil substrates, some of which also contained a layer of NaF. Secondary phases, defects, and defect clusters were different in the various samples, and the surface electrical characteristics of the CZTSSe absorber layer varied accordingly. In contrast to those in the CIGS-based cells, defects and defect clusters generated in the CZTSSe absorber layer caused an upward band bending-like band structure to form at the grain boundaries (GBs), thereby forming an intra-grain (IG) current path. By improving carrier separation, a flexible CZTSSe thin-film solar cell was developed on a Mo foil substrate with a power conversion efficiency of 7.04%. Thus, the efficiency of CZTSSe thin-film solar cells could be increased through carrier separation measures that enabled the collection of holes toward the GBs and of electrons toward IGs.

Cu ₂ ZnSn（S，Se）S ₄（CZTSSe）薄膜作为低成本的太阳能电池吸收材料备受关注。然而，需要进一步的研究以由这种材料开发柔性太阳能电池并实现高功率转换效率。为了实现这一目标，这项工作研究了八种类型的前体，这些前体应用于柔性Mo箔基材上，其中一些还包含一层NaF。在各个样品中，次生相，缺陷和缺陷簇不同，并且CZTSSe吸收层的表面电特性也相应变化。与基于CIGS的单元相反，在CZTSSe吸收层中产生的缺陷和缺陷簇导致在晶粒边界（GBs）处形成向上的带弯曲状能带结构，从而形成晶粒内（IG）电流小路。通过改善载流子分离，在Mo箔基板上开发了一种柔性CZTSSe薄膜太阳能电池，其功率转换效率为7.04％。因此，可以通过载流子分离措施提高CZTSSe薄膜太阳能电池的效率，该措施可以收集朝向GBs的空穴和朝向IGs的电子。