Ge Sijie, Gao Heng, Hong Ruijiang, Li Jianjun, Mai Yaohua, Lin Xianzhong, Yang Guowei
School of Materials Science and Engineering, Sun Yat-Sen University, Guangzhou, 510275, China.
Key Laboratory of Polymeric Composite and Functional Materials of Ministry of Education, Sun Yat-Sen University, Guangzhou, 510275, China.
ChemSusChem. 2019 Apr 23;12(8):1692-1699. doi: 10.1002/cssc.201803009. Epub 2019 Apr 1.
Cu ZnSn(S,Se) (CZTSSe) solar cells based on dimethyl sulfoxide (DMSO) Cu-Zn-Sn-S precursor ink have seen tremendous progress in recent years. However, the wettability between the ink and Mo substrate is poor, owing to the high viscosity of the highly concentrated Cu-Zn-Sn-S ink. Herein, a solvent engineering process is proposed in which N,N-dimethylformamide (DMF) is added into the DMSO-based Cu-Zn-Sn-S ink for the deposition of CZTSSe thin-film absorbers in air. The addition of DMF significantly improves the wettability between the precursor ink and Mo substrate. The DMF/(DMF+DMSO) ratio also plays a critical role in determining the crystal quality of the resulting CZTSSe absorber and the device performance. The grain size of CZTSSe thin films increases with increasing DMF/(DMF+DMSO) ratio. Particularly, large grains through the whole cross section can be achieved with 20 % DMF addition. Accordingly, the power conversion efficiency of the device increases from 6.5 % to 8.6 % under AM 1.5G illumination. However, the efficiency decreases to 5.4 % when the DMF content is further increased to 30 %. Interface recombination and back contact barrier are found to be the main limitations of these devices.
近年来，基于二甲基亚砜（DMSO）铜锌锡硫前驱体油墨的铜锌锡硫硒（CZTSSe）太阳能电池取得了巨大进展。然而，由于高浓度铜锌锡硫油墨的高粘度，油墨与钼衬底之间的润湿性较差。在此，提出了一种溶剂工程方法，即将N，N-二甲基甲酰胺（DMF）添加到基于DMSO的铜锌锡硫油墨中，用于在空气中沉积CZTSSe薄膜吸收层。DMF的添加显著提高了前驱体油墨与钼衬底之间的润湿性。DMF/（DMF+DMSO）的比例在决定所得CZTSSe吸收层的晶体质量和器件性能方面也起着关键作用。CZTSSe薄膜的晶粒尺寸随着DMF/（DMF+DMSO）比例的增加而增大。特别是，添加20%的DMF可以在整个横截面获得大晶粒。相应地，在AM 1.5G光照下，器件的功率转换效率从6.5%提高到8.6%。然而，当DMF含量进一步增加到30%时，效率降至5.4%。界面复合和背接触势垒被发现是这些器件的主要限制因素。
