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Low-temperature and effective ex situ group V doping for efficient polycrystalline CdSeTe solar cells

Nature Energy volume 6, pages 715–722 (2021)Cite this article

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Abstract

CdTe solar cell technology is one of the lowest-cost methods of generating electricity in the solar industry, benefiting from fast CdTe absorber deposition, CdCl2 treatment and Cu doping. However, Cu doping has low photovoltage and issues with instability. Doping group V elements into CdTe is therefore a promising route to address these challenges. Although high-temperature in situ group V doped CdSeTe devices have demonstrated efficiencies exceeding 20%, they face obstacles including post-deposition doping activation processes, short carrier lifetimes and low activation ratios. Here, we demonstrate low-temperature and effective ex situ group V doping for CdSeTe solar cells using group V chlorides. For AsCl3 doped CdSeTe solar cells, the dopant activation ratio can be 5.88%, hole densities reach >2 × 1015 cm−3 and carrier lifetime is longer than 20 ns. Thus, ex situ As doped CdSeTe solar cells show open-circuit voltages ~863 mV, compared to the highest open-circuit voltage of 852 mV for Cu doped CdSeTe solar cells.

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Fig. 1: Schematic of low-temperature ex situ doping in polycrystalline CdSeTe solar cells.
Fig. 2: Characterizations of dopant distribution and the formation of shallow acceptor states.
Fig. 3: Improvement of AsCl3 doped Cu-free CdSeTe device performances.
Fig. 4: Absorber hole lifetime and hole densities.

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All data generated or analysed during this study are included in the published article and its Supplementary Information. Source data are provided with this paper.

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Acknowledgements

S.N.V., L.L. and F.Y. acknowledge funding from the National Science Foundation under contracts no. 1944374 and 2019473, the National Aeronautics and Space Administration, Alabama EPSCoR International Space Station Flight Opportunity Program (contract no. 80NSSC20M0141) and the US Department of Energy’s Office of Energy Efficiency and Renewable Energy (EERE) under the Solar Energy Technologies Office (SETO) Agreement DE-EE0009368. D.-B.L., C.Y., R.A.A., K.K.S., R.J.E. and Y.Y. acknowledge funding from the Air Force Research Laboratory, Space Vehicles Directorate (contract no. FA9453-18-2-0037), the National Science Foundation under contract no. 1711534 and the US Department of Energy’s Office of Energy Efficiency and Renewable Energy (EERE) under Solar Energy Technologies Office (SETO) Agreement DE-EE0008974. We thank D. Strickler from Pilkington North America Inc. for supplying us with the FTO coated substrates.

Author information

Authors and Affiliations

  1. Department of Physics and Astronomy and Wright Center for Photovoltaics Innovation and Commercialization, University of Toledo, Toledo, OH, USA

    Deng-Bing Li, Canglang Yao, Rasha A. Awni, Kamala K. Subedi, Randy J. Ellingson & Yanfa Yan

  2. Department of Metallurgical and Materials Engineering, The University of Alabama, Tuscaloosa, AL, USA

    S. N. Vijayaraghavan, Lin Li & Feng Yan

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  1. Deng-Bing Li
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Contributions

D.-B.L. and S.N.V. performed film and device synthesis as well as J–V, EQE and C–V measurements. S.N.V. performed the XPS measurements. C.Y. performed the DFT calculations. R.A.A. carried out TAS and temperature-dependent J–V measurements. K.K.S. and R.J.E. performed the PL and TRPL measurements. L.L. performed the PL mapping. Y.Y. and F.Y. directed the research.

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Correspondence to Yanfa Yan or Feng Yan.

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Peer review information Nature Energy thanks Gang Xiong and the other, anonymous, reviewer(s) for their contribution to the peer review of this work.

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Supplementary information

Supplementary Information

Supplementary Figs. 1–16, Tables 1–4 and references.

Reporting Summary

Supplementary Data

Supplementary Fig 1. DFT calculation for the diffusion barrier of interstitial Cd and As in CdTe. Supplementary Fig. 3. As linear profile. Supplementary Fig. 7. Statistical Source Data. Supplementary Fig. 10. J–V curves under AM1.5 illumination and in the dark for CdSeTe solar cells without any intentional doping. Supplementary Fig. 12. Light soaking test of the Cu and As doped CdTe solar cells at 85 °C under 1 sun. Supplementary Fig. 14. The C–V determined carrier concentration for the group V chlorides doped CdSeTe solar cells. Supplementary Fig. 15. Temperature-dependent capacitance–frequency measurement for the group V doped CdSeTe measured at temperatures from 150 to 310 K with a step size of 10 K to determine the defect states and back-barrier heights. Supplementary Fig. 16. The Arrhenius plots used to calculate the back-barriers.

Source data

Source Data Fig. 2

Characterizations of dopant distribution and the formation of shallow acceptor states.

Source Data Fig. 3

Improvement of AsCl3 doped Cu-free CdSeTe device performances.

Source Data Fig. 4

Absorber hole lifetime and hole densities.

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Li, DB., Yao, C., Vijayaraghavan, S.N. et al. Low-temperature and effective ex situ group V doping for efficient polycrystalline CdSeTe solar cells. Nat Energy 6, 715–722 (2021). https://doi.org/10.1038/s41560-021-00848-z

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