Effect of deposited temperatures of the buffer layer on the band offset of CZTS/In2S3 heterostructure and its solar cell performance

• Published in: 中国物理B：英文版 Vol. 26; no. 4; pp. 356 - 361
• Main Author: 俞金玲 郑重明 董丽美 程树英 赖云锋 郑巧 周海芳 贾宏杰 张红
• Format: Journal Article
• Language: English
• Published: 01.04.2017
• Subjects: X射线光电子能谱; 价带偏移; 太阳能电池; 异质结构; 沉积温度; 电池性能; 硫化铟; 缓冲层
• ISSN: 1674-1056; 2058-3834
• DOI: 10.1088/1674-1056/26/4/046802

The effect of the deposition temperature of the buffer layer In_2S_3 on the band alignment of CZTS/In_2S_3 heterostructures and the solar cell performance have been investigated.The In_2S_3 films are prepared by thermal evaporation method at temperatures of 30,100,150,and 200 ℃,respectively.By using x-ray photoelectron spectroscopy（XPS）,the valence band offsets（VBO） are determined to be-0.28 ±0.1,-0.28 ±0.1,-0.34 ±0.1,and-0.42 ±0.1 eV for the CZTS/In_2S_3heterostructures deposited at 30,100,150,and 200 ℃,respectively,and the corresponding conduction band offsets（CBO）are found to be 0.3 ±0.1,0.41 ±0.1,0.22±0.1,and 0.01 ±0.1 eV,respectively.The XPS study also reveals that interdiffusion of In and Cu occurs at the interface of the heterostructures,which is especially serious at 200 ℃ leading to large amount of interface defects or the formation of CuInS_2 phase at the interface.The CZTS solar cell with the buffer layer In_2S_3 deposited at 150 ℃ shows the best performance due to the proper CBO value at the heterostructure interface and the improved crystal quality of In_2S_3 film induced by the appropriate deposition temperature.The device prepared at 100 ℃presents the poorest performance owing to too high a value of CBO.It is demonstrated that the deposition temperature is a crucial parameter to control the quality of the solar cells.