The conversion efficiency of Cu2ZnSn(S,Se)4 (CZTSSe) solar cells is relatively low, due to the complicated intrinsic defects and the unsuitable contact interfaces. In this work, MoO2 thin films prepared by a simple preannealing method are introduced to Mo/CZTSSe back contact interface. For the first time, it is found that MoO2 acts as a sacrificial layer rather than the traditional intermediate layer. Specifically, the MoO2 sacrificial layer will disappear and become a thin MoSe2 layer after it blocks the over-selenization of Mo electrode. In addition, it has a positive effect on the preferred orientation of MoSe2 and the crystallization of CZTSSe layer. Furthermore, the chemical mechanism on MoO2 as sacrificial layer is first investigated, and it can be well described by Van 't Hoff equation. With the aid of MoO2 sacrificial layer, the performance of CZTSSe device increases from 5.67% to 8.29% (active area efficiency is 9.08%) without the MgF2 antireflection layer.

中文翻译：

---

用于优化 Cu2ZnSn(S,Se)4 太阳能电池背接触界面的 MoO2 牺牲层


由于复杂的本征缺陷和不合适的接触界面，Cu2ZnSn(S,Se)4 (CZTSSe)太阳能电池的转换效率相对较低。在这项工作中，通过简单的预退火方法制备的MoO2薄膜被引入到Mo/CZTSSe背接触界面。首次发现MoO2充当牺牲层而不是传统的中间层。具体来说，MoO2牺牲层在阻挡Mo电极的过度硒化后会消失并变成一层薄的MoSe2层。此外，它对MoSe2的择优取向和CZTSSe层的结晶有积极的影响。此外，首次研究了MoO2作为牺牲层的化学机理，并且可以用Van't Hoff方程很好地描述。借助MoO2牺牲层，在没有MgF2减反射层的情况下，CZTSSe器件的性能从5.67%提高到8.29%（有源区效率为9.08%）。