Passivating contacts for crystalline silicon solar cells

Abstract

The global photovoltaic (PV) market is dominated by crystalline silicon (c-Si) based technologies with heavily doped, directly metallized contacts. Recombination of photo-generated electrons and holes at the contact regions is increasingly constraining the power conversion efficiencies of these devices as other performance-limiting energy losses are overcome. To move forward, c-Si PV technologies must implement alternative contacting approaches. Passivating contacts, which incorporate thin films within the contact structure that simultaneously supress recombination and promote charge-carrier selectivity, are a promising next step for the mainstream c-Si PV industry. In this work, we review the fundamental physical processes governing contact formation in c-Si. In doing so we identify the role passivating contacts play in increasing c-Si solar cell efficiencies beyond the limitations imposed by heavy doping and direct metallization. Strategies towards the implementation of passivating contacts in industrial environments are discussed.

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Fig. 1: Historical progression of notable c-Si solar cell efficiencies.
Fig. 2: Conceptual schematic of the operation of a solar cell.
Fig. 3: Motivation for, and characteristics of, heavily doped contacts.
Fig. 4: Solar cells featuring passivating contacts.
Fig. 5: Materials for passivating contacts.
Fig. 6: Comparison of silicon solar cell contacting approaches.

Data availability

The data from plots in Figs. 1a,b, 3f,g, 5 and 6a are available in the Supplementary Data.

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Acknowledgements

The work was supported by funding from King Abdullah University of Science and Technology (KAUST) Office of Sponsored Research (OSR) under award no. OSR-CRG URF/1/3383, as well as funding from Saudi Aramco. Figures 2 and 4, as well as the text box images, were created by Heno Hwang, scientific illustrator at KAUST. T.G.A. and J.B. would like to thank prof. Andres Cuevas for guidance and feedback related to the physics of passivating contacts.

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Correspondence to Stefaan De Wolf.

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Supplementary Data 1

Data from plots in Figs. 1a,b, 3f,g, 5 and 6a.

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Allen, T.G., Bullock, J., Yang, X. et al. Passivating contacts for crystalline silicon solar cells. Nat Energy 4, 914–928 (2019). https://doi.org/10.1038/s41560-019-0463-6

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