High-performance perovskite/silicon heterojunction solar cells enabled by industrially compatible post annealing
Guangyi Wang1, Zongyi Yue1, Zengguang Huang1, Wenzhu Liu2, Rui Tong3, Haipeng Yin3, Lifei Yang4, Fucheng Yu1, Zongyang Sun5 and Sihua Zhong*,1
  1. School of Science, Jiangsu Ocean University, Lianyungang, Jiangsu Province 222005, China
  2. Research Center for New Energy Technology, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, Shanghai 201800, China
  3. JA Solar, Yangzhou, Jiangsu Province 225131, China
  4. SuZhou GH New Energy Tech. Co., Ltd, Suzhou, Jiangsu Province 215168, China
  5. Jinghaiyang Semiconductor Materials Co., Ltd, Lianyungang, Jiangsu Province 222399, China
*Corresponding author, E-mail: shzhong@jou.edu.cn
In recent years, developing dopant-free carrier-selective contacts, instead of heavily doped Si layer (either externally or internally), for crystalline silicon (c-Si) solar cells have attracted considerable interests with the aims to reduce parasitic light absorption and fabrication cost. However, the stability still remains a big challenge for dopant-free contacts, especially when thermal treatment is involved, which limits their industrial adoption. In this study, a perovskite material ZnTiO3 combining with an ultrathin (~1 nm) SiO2 film and Al layer is used as an electron-selective contact, forming an isotype heterojunction with n-type c-Si. The perovskite/c-Si heterojunction solar cells exhibit a performance-enhanced effect by post-metallization annealing when the annealing temperature is 200-350 °C. Thanks to the post-annealing treatment, an impressive efficiency of 22.0% has been demonstrated, which is 3.5% in absolute value higher than that of the as-fabricated solar cell. A detailed material and device characterization reveal that post annealing leads to the diffusion of Al into ZnTiO3film, thus doping the film and reducing its work function. Besides, the coverage of SiO2 is also improved. Both these two factors contribute to the enhanced passivation effect and electron selectivity of the ZnTiO3-based contact, and hence improve the cell performance.
Keywords: perovskite, dopant-free, carrier-selective contacts, thermal stability, silicon solar cells.