Efficiency enhancement of Cu2ZnSn(S,Se)4 solar cells by S-modified surface layer
Efficiency enhancement of Cu2ZnSn(S,Se)4 solar cells by S-modified surface layer
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DOI：
10.1016/j.solmat.2016.12.033
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发表时间：
2017-04-01
影响因子：
6.9
通讯作者：
Lai, Chih-Huang
中科院分区：
文献类型：
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作者：
Cai, Chung-Hao;Wei, Shih-Yuan;Lai, Chih-Huang
我们展示了一种简单的方法来制备具有增加的硫含量表面的Cu2ZnSn（S，Se）（4）（CZTSSe）吸收体。众所周知，CZTSSe太阳能电池中的界面复合问题是进一步提高效率的问题。报道了Cu（In，Ga）（S，Se）（2）太阳电池表面硫化的有益效果。然而，表面硫化对CZTSSe太阳能电池的影响报道非常有限，这是改善表面并实现更高效率的关键因素。在这项工作中，我们制造的CZTSSe吸收剂硒化的含硫堆叠前体。通过在硒化过程的冷却阶段期间引入H2S气体来实现硫改性的表面。研究了表面硫化对CZTSSe的组成、结构、形貌和电性能的影响。由于前表面带隙的增加和界面复合的减少，开路电压可以从312 mV（无H2S）显著增加到400 mV（有H2S）。H_2S气体的表面钝化改善了表面的局域电性能，降低了界面缺陷密度。CZTSSe太阳能电池的效率从5.01%（不含H2S）大幅提高到7.38%（含H2S）。该方法可以很容易地应用到各种CZTSSe工艺中，以钝化表面并形成更大的表面带隙，从而降低界面复合，这为进一步提高CZTSSe效率铺平了新的途径。
We demonstrate a simple approach to fabricate Cu2ZnSn(S, Se)(4) (CZTSSe) absorber with increased-sulfur content surface. It is well known that the problem of interface recombination in CZTSSe solar cells is the issue for further improving efficiency. The beneficial effects of surface sulfurization were reported in Cu(In, Ga)(S, Se)(2) solar cells. However, very limited works have been reported on the effects of surface sulfurization on CZTSSe solar cells, which is a critical factor to improve the surface and achieve higher efficiency. In this work, we fabricate the CZTSSe absorber by selenizing the sulfur-containing stacked precursors. The sulfur-modified surface is achieved by introducing H2S gas during cooling stage of the selenization process. The effects of surface sulfurization on composition, structure, morphology, and electric properties of CZTSSe are thoroughly investigated. The open circuit voltage can be increased significantly from 312 mV (without H2S) to 400 mV (with H2S) due to the increment of front surface bandgap and reduction of interface recombination. Surface localized electric properties are improved, and interface defect density is decreased due to surface passivation by using H2S gas. The efficiency of CZTSSe solar cell substantially increases from 5.01% (without H2S) to 7.38% (with H2S). The proposed approach can be easily applied to various CZTSSe processes to passivate the surface and form larger surface bandgap, leading to lower interface recombination, which paves a new avenue to further improve the CZTSSe efficiency.