Heavy Boron-Doped Silicon Tunneling Inter-layer Enables Efficient Silicon Heterojunction Solar Cells

• Published in: ACS applied materials & interfaces 2024-09, Vol.16 (35), p.46889-46896
• Main Authors: Zhou, Yinuo, Zhang, Honghua, Li, Zhenfei, Huang, Shenglei, Du, Junlin, Han, Anjun, Shi, Jianhua, Wang, Guangyuan, Shi, Qiang, Zhao, Wenjie, Fu, Haoxin, Fan, Bin, Meng, Fanying, Liu, Wenzhu, Liu, Zhengxin, Zhang, Liping
• Format: Article
• Language: English
• Subjects: boron; electric field; energy; hydrogen; nanocrystals; silane; silica; silicon; Surfaces, Interfaces, and Applications; transportation
• ISSN: 1944-8244; 1944-8252; 1944-8252
• DOI: 10.1021/acsami.4c07897

P-type hydrogenated nanocrystalline silicon (nc-Si:H) has been used as a hole-selective layer for efficient n-type crystalline silicon heterojunction (SHJ) solar cells. However, the presence of an additional valence band offset at the interface between intrinsic amorphous hydrogenated silicon and p-type nc-Si:H films will limit the hole carrier transportation. In this work, it has been found that when a heavily boron-doped silicon oxide layer deposited with high hydrogen dilution to silane (pB) was inserted into their interface, the fill factor of SHJ solar cells increases 3% absolutely because of the reduced valence band offset and the increased opportunity to provide a hopping tunnel assisted by the doping energy level and valence band tail states. Furthermore, the additional boron incorporation in intrinsic amorphous silicon adjacent to pB helps to enhance the built-in electric field, thus increasing the hole selectivity. By these means, the power conversion efficiency was improved from 23.9% to approximately 25%.