开路电压过低一直是限制锌黄锡矿Cu2ZnSn(SSe)4（CZTSSe）太阳能电池进一步发展和利用的关键因素。将CZTSSe吸收层表层设计成稳定的弱n型特征可以有效地实现CZTSSe/CdS界面p-n型转变，从而大幅提高开路电压。以前的研究几乎无法同时达到稳定性和n型化的表层设计。基于第一性原理计算，我们提出两种解决方案：（1）在CZTSSe吸收层表层掺入离子半径较大且无s-d轨道耦合的金属元素，使其在提高掺杂元素扩散势垒的同时诱导界面处于弱n型特征。（2）CZTSSe表层掺杂形成类似于CuInSe2表层的稳定弱n型宽带隙二次相，使CZTSSe/CdS界面形成较大的带边弯曲，提高器件的开路电压。在此基础上，我们尝试采用不同离子半径的碱金属后处理调节界面带边弯曲的程度。本项目的成功实施将有助于揭示掺杂对开路电压和界面稳定性的调控机制，为锌黄锡矿太阳能电池器件的界面设计提供理论支持。

The development and utilization of kesterite solar cells are still currently stalemated by their low open voltage. The design of CZTSSe contact layers on the side of CZTSSe/CdS interface into weak n-type can effectively realize the interface p to n transformation, thus greatly increasing the open voltage. Almost all the previous studies failed to achieve both the stability and n-type design of CZTSSe surface layers. Here, using the First-principles calculations, we propose two different approaches: (1) Doping ions with large radius avoiding s-d orbital coupling make the interface a n-type with a high ion diffusion barrier. (2) Doping in CZTSSe surface layer forms the stable broadband gap secondary phase with weak n-type characteristic, resulting in the large band bending near the CZTSSe/CdS interface and improving the open voltage that is similar with the situation of CIGS/CdS. Furthermore, we attempt to adjust the n-type strength of the interface by the post-treatment of the different kinds of alkali metals. The successful implementation of this project will help us to understand the doping effect on the improvement of open voltage and stability of the interface, and provide a theoretical guidance for experimentally synthesizing the stable and high efficient CZTSSe solar cell devices.