Li_(2)S doping into CZTSe drives the large improvement of V_(OC) of solar cell  

作　　者：Zhan Shen Siyu Wang Yue Liu Yali Sun Jianyu Wu Hongling Guo Kaizhi Zhang Shengli Zhang Fangfang Liu Yi Zhang 

机构地区：[1]Institute of Photoelectronic Thin Film Devices and Technology and Tianjin Key Laboratory of Photoelectronic Thin Film Devices and Technology,and Renewable Energy Conversion and Storage Center,Nankai University,Tianjin 300350,China

出　　处：《Journal of Energy Chemistry》2021年第11期637-644,I0015,共9页能源化学（英文版）

基　　金：This work was supported by the National Key R&D Program of China(2018YFB1500200,2019YFB1503500);the National Natural Science Foundation of China(U1902218,11774187);the 111 Project(B16027).

摘　　要：Alkali metal doping or sulfurization are commonly applied in Cu_(2)ZnSnSe_(4) (CZTSe) solar cell to improve the open-circuit voltage (VOC). However, alkali metal sulfide affording both alkali metal and sulfur is seldom to be studied, which restrains the development of kesterite solar cells. In this study, we evaporate Li_(2)S during selenization process and hope to provide both alkali metal and sulfur to CZTSe film. The result indicates that Li shows a gradient distribution near the surface of CZTSe film and the content of S is slight. The film quality is improved and the recombination at grain boundaries is decreased after Li_(2)S treatment. Besides, the bandgap of the absorber gets wider. Under the synergy of sulfur and lithium (mainly from lithium), the work function of the treated absorber gets higher and the conduction band offset (CBO) is in the ideal range. Combined with these contributions, the V_(OC) of the champion device treated by Li_(2)S dramatically increase by 120 mV. This study discloses that alkali metal brings the main effect on the performance of the kesterite solar cell even an alkali metal sulfide is evaporated, which deepens the understanding of sulfurization of CZTSe and also promote the progress of kesterite solar cells.

关 键 词：Li_(2)S treatment Surface passivation V_(OC)enhancement Band alignment 

分 类 号：TM914.4[电气工程—电力电子与电力传动] TB383.2[一般工业技术—材料科学与工程]