Light-induced activation of boron doping in hydrogenated amorphous silicon for over 25% efficiency silicon solar cells

Abstract
Recent achievements in amorphous/crystalline silicon heterojunction (SHJ) solar cells and perovskite/SHJ tandem solar cells place hydrogenated amorphous silicon (a-Si:H) at the forefront of photovoltaics. Due to the extremely low effective doping efficiency of trivalent boron in amorphous tetravalent silicon, light harvesting of aforementioned devices is limited by their fill factors (FFs), a direct metric of the charge carrier transport. It is challenging but crucial to develop highly conductive doped a-Si:H with minimal FF losses. Here we report that light soaking can efficiently boost the dark conductance of boron-doped a-Si:H thin films. Light induces diffusion and hopping of weakly bound hydrogen atoms, which activates boron doping. The effect is reversible and the dark conductivity decreases over time when the solar cell is no longer illuminated. By implementing this effect to SHJ solar cells, we achieved a certified total-area power conversion efficiency of 25.18% with a FF of 85.42% on a 244.63 cm2 wafer.

Citation
Liu, W., Shi, J., Zhang, L., Han, A., Huang, S., Li, X., Peng, J., Yang, Y., Gao, Y., Yu, J., Jiang, K., Yang, X., Li, Z., Zhao, W., Du, J., Song, X., Yin, J., Wang, J., Yu, Y., … Liu, Z. (2022). Light-induced activation of boron doping in hydrogenated amorphous silicon for over 25% efficiency silicon solar cells. Nature Energy. https://doi.org/10.1038/s41560-022-01018-5

Acknowledgements
W.L. acknowledges professor Z. Ma and W. Ji for their fruitful discussions. W.L. acknowledges the financial supports from National Natural Science Foundations of China (grant no. 62004208) and Science and Technology Commission of Shanghai Municipality (grant no. 22ZR1473200). L.Z. acknowledges the financial support from National Natural Science Foundations of China (grant no. 62074153). A.H. acknowledges the financial support from Science and Technology Commission of Shanghai Municipality (grant no. 19DZ1207602).

Publisher
Springer Science and Business Media LLC

Journal
Nature Energy

DOI
10.1038/s41560-022-01018-5

Additional Links
https://www.nature.com/articles/s41560-022-01018-5

Permanent link to this record