Article

Monocrystalline CdTe solar cells with open-circuit voltage over 1 V and efficiency of 17%

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Abstract

The open-circuit voltages of mature single-junction photovoltaic devices are lower than the bandgap energy of the absorber, typically by a gap of 400 mV. For CdTe, which has a bandgap of 1.5 eV, the gap is larger; for polycrystalline samples, the open-circuit voltage of solar cells with the record efficiency is below 900 mV, whereas for monocrystalline samples it has only recently achieved values barely above 1 V. Here, we report a monocrystalline CdTe/MgCdTe double-heterostructure solar cell with open-circuit voltages of up to 1.096 V. The latticed-matched MgCdTe barrier layers provide excellent passivation to the CdTe absorber, resulting in a carrier lifetime of 3.6 μs. The solar cells are made of 1- to 1.5-μm-thick n-type CdTe absorbers, and passivated hole-selective p-type a-SiCy:H contacts. This design allows CdTe solar cells to be made thinner and more efficient. The best power conversion efficiency achieved in a device with this structure is 17.0%.

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References

  1. 1.

    , , ,  & Solar cell efficiency tables (version 47). Prog. Photovolt. Res. Appl. 24, 3–11 (2016).

  2. 2.

    Optical Constants of Crystalline and Amorphous Semiconductors: Numerical Data and Graphical Information (Springer, 1999);

  3. 3.

    et al. Enhanced p-type dopability of P and As in CdTe using non-equilibrium thermal processing. J. Appl. Phys. 118, 025102 (2015).

  4. 4.

    et al. 27.6% conversion efficiency, a new record for single-junction solar cells under 1 sun illumination. Conf. Rec. 37th IEEE Photovolt. Spec. Conf. 000004–000008 (2011).

  5. 5.

    et al. Research strategies toward improving thin-film CdTe photovoltaic devices beyond 20% conversion efficiency. Sol. Energy Mater. Sol. Cells 119, 149–155 (2013).

  6. 6.

    et al. Minority carrier lifetime analysis in the bulk of thin-film absorbers using subbandgap (two-photon) excitation. IEEE J. Photovolt. 3, 1319–1324 (2013).

  7. 7.

    ,  & High efficiency indium oxide/cadmium telluride solar cells. Appl. Phys. Lett. 50, 279–280 (1987).

  8. 8.

    et al. CdTe solar cells with open-circuit voltage greater than 1 V. Nature Energy 1, 16015 (2016).

  9. 9.

    et al. Influence of Cds/CdTe interface properties on the device properties. Conf. Rec. 26th IEEE Photovolt. Spec. Conf. 435–438 (1997).

  10. 10.

    ,  & CdTe solar cells at the threshold to 20% efficiency. IEEE J. Photovoltaics 3, 1389–1393 (2013).

  11. 11.

    , , ,  & Growth, steady-state, and time-resolved photoluminescence study of CdTe/MgCdTe double heterostructures on InSb substrates using molecular beam epitaxy. Appl. Phys. Lett. 103, 193901 (2013).

  12. 12.

    , , ,  & Determination of CdTe bulk carrier lifetime and interface recombination velocity of CdTe/MgCdTe double heterostructures grown by molecular beam epitaxy. Appl. Phys. Lett. 105, 252101 (2014).

  13. 13.

    et al. Carrier lifetimes and interface recombination velocities in CdTe/MgxCd1-xTe double heterostructures with different Mg compositions grown by molecular beam epitaxy. Appl. Phys. Lett. 107, 041120 (2015).

  14. 14.

    et al. CdTe/MgTe heterostructures: growth by atomic layer epitaxy and determination of MgTe parameters. J. Appl. Phys. 80, 6257–6265 (1996).

  15. 15.

    et al. Optical investigation of confinement and strain effects in CdTe/(CdMg)Te quantum wells. Appl. Phys. Lett. 63, 2932–2934 (1993).

  16. 16.

    et al. Optical enhancement of the open-circuit voltage in high quality GaAs solar cells. J. Appl. Phys. 113, 123109 (2013).

  17. 17.

    et al. Time-resolved and excitation-dependent photoluminescence study of CdTe/MgCdTe double heterostructures grown by molecular beam epitaxy. J. Vac. Sci. Technol. B 32, 040601 (2014).

  18. 18.

    , , ,  & Ultralow recombination velocity at Ga0.5In0.5P/GaAs heterointerfaces. Appl. Phys. Lett. 55, 1208–1210 (1989).

  19. 19.

     & Very low interface recombination velocity in (Al,Ga)As heterostructures grown by organometallic vapor-phase epitaxy. J. Appl. Phys. 64, 4253–4256 (1988).

  20. 20.

    et al. Achievement of more than 25% conversion efficiency with crystalline silicon heterojunction solar cell. IEEE J. Photovolt. 4, 1433–1435 (2014).

  21. 21.

    et al. Monocrystalline ZnTe/CdTe/MgCdTe double heterostructure solar cells grown on InSb substrates. Conf. Rec. 42nd IEEE Photovolt. Spec. Conf. 7355652 (2015).

  22. 22.

    et al. Silicon heterojunction solar cell with passivated hole selective MoOx contact. Appl. Phys. Lett. 104, 113902 (2014).

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Author information

Affiliations

  1. Center for Photonics Innovation, Arizona State University, Tempe, Arizona 85287, USA

    • Yuan Zhao
    • , Shi Liu
    • , Jacob Becker
    • , Xin-Hao Zhao
    • , Calli M. Campbell
    • , Ernesto Suarez
    • , Maxwell B. Lassise
    •  & Yong-Hang Zhang
  2. School of Electrical, Computer and Energy Engineering, Arizona State University, Tempe, Arizona 85287, USA

    • Yuan Zhao
    • , Mathieu Boccard
    • , Shi Liu
    • , Jacob Becker
    • , Ernesto Suarez
    • , Maxwell B. Lassise
    • , Zachary Holman
    •  & Yong-Hang Zhang
  3. School for Engineering of Matter, Transport and Energy, Arizona State University, Tempe, Arizona 85287, USA

    • Xin-Hao Zhao
    •  & Calli M. Campbell

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Contributions

Y.-H.Z. proposed the ideas to use InSb substrate and DH structure; Y.Z. modelled the device and first proposed the use of a-Si:H as a hole-contact layer on the front MgCdTe barrier; M.B. and Y.Z. then extended the idea to the a-SiCy:H hole-contact layer; S.L. designed and grew DH PL samples; C.M.C., M.L. and E.S. grew the device wafers and participated in editing of the manuscript; X.-H.Z. did XRD measurements and analysis, and together with S.L. analysed the TRPL results and built the theoretical model, M.B. deposited the ITO and hole-contact layers, and processed all the devices; Y.Z., J.B. and M.B. characterized and modelled the device and analysed the results; the manuscript was mainly written by Y.Z., J.B., M.B., X.-H.Z., Z.H., Y.-H.Z., with Y.-H.Z. leading the entire project.

Competing interests

The authors declare no competing financial interests.

Corresponding author

Correspondence to Yong-Hang Zhang.