Atomic Layer Deposition of Vanadium Oxide as Hole-Selective Contact for Crystalline Silicon Solar Cells

Abstract
High carrier recombination loss at the contact regions has become the dominant factor limiting the power conversion efficiency (PCE) of crystalline silicon (c-Si) solar cells. Dopant-free carrier-selective contacts are being intensively developed to overcome this challenge. In this work, vanadium oxide (VOx ) deposited by atomic layer deposition (ALD) is investigated and optimized as a potential hole-selective contact for c-Si solar cells. ALD VOx films are demonstrated to simultaneously offer a good surface passivation and an acceptable contact resistivity (ρc) on c-Si, achieving a best contact recombination current density (J 0) of ≈40 fA cm−2 and a minimum ρc of ≈95 mΩ.cm2. Combined with a high work function of 6.0 eV, ALD VOx films are proven to be an effective hole-selective contact on c-Si. By the implementation of hole-selective VOx contact, the state-of-the-art PCE of 21.6% on n-type c-Si solar cells with a high stability is demonstarted. These results demonstrate the high potential of ALD VOx as a stable hole-transport layer for photovoltaic devices, with applications beyond c-Si, such as perovskite and organic solar cells.

Citation
Yang, X., Xu, H., Liu, W., Bi, Q., Xu, L., Kang, J., … De Wolf, S. (2020). Atomic Layer Deposition of Vanadium Oxide as Hole-Selective Contact for Crystalline Silicon Solar Cells. Advanced Electronic Materials, 2000467. doi:10.1002/aelm.202000467

Acknowledgements
The work presented in this publication was financially supported by King Abdullah University of Science and Technology (KAUST), through the Competitive Research Grant. B.S. and X.Z. acknowledge the National Natural Science Foundation of China (No. 91833303). The authors would like to thank Dr. Michele De Bastiani and Dr. Thomas Allen in KAUST for helping the device fabrication and Dr. Ziv Hameiri (University of New South Wales) for conducting the contactless capacitance–voltage (C–V ) measurements. The authors also thank Heno Hwang, scientific illustrator at KAUST, for producing Figure 5a.

Publisher
Wiley

Journal
Advanced Electronic Materials

DOI
10.1002/aelm.202000467

Additional Links
https://onlinelibrary.wiley.com/doi/abs/10.1002/aelm.202000467

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