Skip to main content

Thank you for visiting nature.com. You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.

  • Article
  • Published:

CdTe solar cells with open-circuit voltage breaking the 1 V barrier

Nature Energy volume 1, Article number: 16015 (2016) Cite this article

Subjects

A Corrigendum to this article was published on 11 April 2016

Abstract

CdTe solar cells have the potential to undercut the costs of electricity generated by other technologies, if the open-circuit voltage can be increased beyond 1 V without significant decreases in current. However, in the past decades, the open-circuit voltage has stagnated at around 800–900 mV. This is lower than in GaAs solar cells, even though GaAs has a smaller bandgap; this is because it is more difficult to achieve simultaneously high hole density and lifetime in II–VI materials than in III–V materials. Here, by doping the CdTe with a Group V element, we report lifetimes in single-crystal CdTe that are nearly radiatively limited and comparable to those in GaAs over a hole density range relevant for solar applications. Furthermore, the deposition on CdTe of nanocrystalline CdS layers that form non-ideal heterointerfaces with 10% lattice mismatch impart no damage to the CdTe surface and show excellent junction transport properties. These results enable the fabrication of CdTe solar cells with open-circuit voltage greater than 1 V.

This is a preview of subscription content, access via your institution

Access options

Buy this article

  • Purchase on Springer Link
  • Instant access to full article PDF
Buy now

Prices may be subject to local taxes which are calculated during checkout

Figure 1: Non-ideal interfaces in thin-film technologies.
Figure 2: CdTe lifetimes and hole densities comparable to GaAs.
Figure 3: High-resolution imaging of a high-performance, lattice-mismatched interface.
Figure 4: Low surface recombination occurs across a true lattice-mismatched heterojunction.
Figure 5: Overcoming the historical voltage barrier.

Similar content being viewed by others

References

  1. Bhargava, R. (ed.) Properties of Wide Bandgap II–VI Semiconductors (INSPEC, 1997).

    Google Scholar 

  2. Ma, J., Wei, S.-H., Gessert, T. A. & Chin, K. K. Carrier density and compensation in semiconductors with multiple dopants and multiple transition energy levels: case of Cu impurities in CdTe. Phys. Rev. B 83, 245207 (2011).

    Article  Google Scholar 

  3. Luque, A. & Hegedus, S. (eds) Handbook of Photovoltaic Science and Engineering Ch. 13, 14 (Wiley, 2011).

    Google Scholar 

  4. Kranz, L. et al. Doping of polycrystalline CdTe for high-efficiency solar cells on flexible metal foil. Nature Commun. 4, 2306 (2013).

    Article  Google Scholar 

  5. Liu, M., Johnston, M. B. & Snaith, H. J. Efficient planar heterojunction perovskite solar cells by vapour deposition. Nature 501, 395–398 (2013).

    Article  Google Scholar 

  6. Mahabaduge, H. P. et al. High-efficiency, flexible CdTe solar cells on ultra-thin glass substrates. Appl. Phys. Lett. 106, 133501 (2015).

    Article  Google Scholar 

  7. Li, G., Zhu, R. & Yang, Y. Polymer solar cells. Nature Photon. 6, 153–161 (2012).

    Article  Google Scholar 

  8. Yang, W. S. et al. High-performance photovoltaic perovskite layers fabricated through intramolecular exchange. Science 348, 1234–1237 (2015).

    Article  Google Scholar 

  9. Reinhard, P. et al. Review of progress toward 20% efficiency flexible CIGS solar cells and manufacturing issues of solar modules. IEEE J. Photovolt. 3, 572–580 (2013).

    Article  Google Scholar 

  10. Chirilă, A. et al. Potassium-induced surface modification of Cu(In,Ga)Se2 thin films for high-efficiency solar cells. Nature Mater. 12, 1107–1111 (2013).

    Article  Google Scholar 

  11. Jaegermann, W., Klein, A. & Mayer, T. Interface engineering of inorganic thin-film solar cells – materials-science challenges for advanced physical concepts. Adv. Mater. 21, 4196–4206 (2009).

    Article  Google Scholar 

  12. Kumar, S. G. & Rao, K. Physics and chemistry of CdTe/CdS thin film heterojunction photovoltaic devices: fundamental and critical aspects. Energy Environ. Sci. 7, 45–102 (2014).

    Article  Google Scholar 

  13. Gloeckler, M. & Sites, J. R. Efficiency limitations for wide-band-gap chalcopyrite solar cells. Thin Solid Films 480, 241–245 (2005).

    Article  Google Scholar 

  14. Zhou, H. et al. Interface engineering of highly efficient perovskite solar cells. Science 345, 542–546 (2014).

    Article  Google Scholar 

  15. Simonds, B. J., Kheraj, V., Palekis, V., Ferekides, C. & Scarpulla, M. A. Reduction of Fermi level pinning and recombination at polycrystalline CdTe surfaces by laser irradiation. J. Appl. Phys. 117, 225301 (2015).

    Article  Google Scholar 

  16. Minemoto, T. et al. Control of conduction band offset in wide-gap Cu(In,Ga)Se2 solar cells. Sol. Energy Mater. Sol. Cells 75, 121–126 (2003).

    Article  Google Scholar 

  17. Page, Z. A., Liu, Y., Duzhko, V. V., Russell, T. P. & Emrick, T. Fulleropyrrolidine interlayers: tailoring electrodes to raise organic solar cell efficiency. Science 346, 441–444 (2014).

    Article  Google Scholar 

  18. CRC Handbook of Chemistry and Physics 84th edn, Section 12 (CRC, 2003).

  19. Metzger, W. K. et al. Time-resolved photoluminescence studies of CdTe solar cells. J. Appl. Phys. 94, 3549–3555 (2003).

    Article  Google Scholar 

  20. Reese, M. O. et al. Intrinsic surface passivation of CdTe. J. Appl. Phys. 118, 155305 (2015).

    Article  Google Scholar 

  21. Terheggen, M. et al. Analysis of bulk and interface phenomena in CdTe/CdS thin-film solar cells. Interface Sci. 12, 259–266 (2004).

    Article  Google Scholar 

  22. Major, J. D., Treharne, R. E., Phillips, L. J. & Durose, K. A low-cost non-toxic post-growth activation step for CdTe solar cells. Nature 511, 334–337 (2014).

    Article  Google Scholar 

  23. deQuilettes, D. W. et al. Impact of microstructure on local carrier lifetime in perovskite solar cells. Science 348, 683–686 (2015).

    Article  Google Scholar 

  24. Metzger, W. K., Albin, D., Romero, M. J., Dippo, P. & Young, M. CdCl2 treatment, S diffusion, and recombination in polycrystalline CdTe. J. Appl. Phys. 99, 103703 (2006).

    Article  Google Scholar 

  25. Kranz, L. et al. Tailoring impurity distribution in polycrystalline CdTe solar cells for enhanced minority carrier lifetime. Adv. Energy Mater. 4, 1301400 (2014).

    Article  Google Scholar 

  26. Moseley, J. et al. Recombination by grain-boundary type in CdTe. J. Appl. Phys. 118, 025702 (2015).

    Article  Google Scholar 

  27. Gessert, T. A. et al. Dependence of carrier lifetime on Cu-contacting temperature and ZnTe:Cu thickness in CdS/CdTe thin film solar cells. Thin Solid Films 517, 2370–2373 (2009).

    Article  Google Scholar 

  28. Korevaar, B. A., Zorn, G., Raghavan, K. C., Cournoyer, J. R. & Dovidenko, K. Cross-sectional mapping of hole concentrations as a function of copper treatment in CdTe photovoltaic devices. Prog. Photovolt. 23, 1466–1474 (2015).

    Article  Google Scholar 

  29. Demtsu, S. H., Albin, D. S., Sites, J. R., Metzger, W. K. & Duda, A. Cu-related recombination in CdS/CdTe solar cells. Thin Solid Films 516, 2251–2254 (2008).

    Article  Google Scholar 

  30. Green, M. A., Emery, K., Hishikawa, Y., Warta, W. & Dunlop, E. D. Solar cell efficiency tables (version 46). Prog. Photovolt. 23, 805–812 (2015).

    Article  Google Scholar 

  31. Gloeckler, M., Sankin, I. & Zhao, Z. CdTe solar cells at the threshold to 20% efficiency. IEEE J. Photovolt. 3, 1389–1393 (2013).

    Article  Google Scholar 

  32. Corwine, C. R., Pudov, A. O., Gloeckler, M., Demtsu, S. H. & Sites, J. R. Copper inclusion and migration from the back contact in CdTe solar cells. Sol. Energy Mater. Sol. Cells 82, 481–489 (2004).

    Google Scholar 

  33. Albin, D. S. Accelerated stress testing and diagnostic analysis of degradation in CdTe solar cells. In Proc. SPIE 7048, Reliability of Photovoltaic Cells, Modules, Components, and Systems (ed. Dhere, N. G. ) 70480N (SPIE, 2008).

    Google Scholar 

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

    Article  Google Scholar 

  35. Biernacki, S., Scherz, U. & Meyer, B. K. Electronic properties of A centers in CdTe: a comparison with experiment. Phys. Rev. B 48, 11726–11731 (1993).

    Article  Google Scholar 

  36. Visoly-Fisher, I., Cohen, S. R., Ruzin, A. & Cahen, D. How polycrystalline devices can outperform single-crystal ones: thin film CdTe/CdS solar cells. Adv. Mater. 16, 879–883 (2004).

    Article  Google Scholar 

  37. Yan, Y. et al. Physics of grain boundaries in polycrystalline photovoltaic semiconductors. J. Appl. Phys. 117, 112807 (2015).

    Article  Google Scholar 

  38. Li, C. et al. Grain-boundary-enhanced carrier collection in CdTe solar cells. Phys. Rev. Lett. 112, 156103 (2014).

    Article  Google Scholar 

  39. Poplawsky, J. D. et al. Direct imaging of Cl- and Cu-induced short-circuit efficiency changes in CdTe solar cells. Adv. Energy Mater. 4, 1400454 (2014).

    Article  Google Scholar 

  40. Metzger, W. K. & Gloeckler, M. The impact of charged grain boundaries on thin-film solar cells and characterization. J. Appl. Phys. 98, 063701 (2005).

    Article  Google Scholar 

  41. Ma, J. et al. Dependence of the minority-carrier lifetime on the stoichiometry of CdTe using time-resolved photoluminescence and first-principles calculations. Phys. Rev. Lett. 111, 067402 (2013).

    Article  Google Scholar 

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

    Article  Google Scholar 

  43. Yang, J. H. et al. Tuning the Fermi level beyond the equilibrium doping limit through quenching: the case of CdTe. Phys. Rev. B 90, 245202 (2014).

    Article  Google Scholar 

  44. O’Connor, D. V. & Phillips, D. Time-Correlated Single Photon Counting (Academic, 1984).

    Google Scholar 

  45. Swartz, C. H. et al. Radiative and interfacial recombination in CdTe heterostructures. Appl. Phys. Lett. 105, 222107 (2014).

    Article  Google Scholar 

  46. Casey, H. C. & Stern, F. Concentration-dependent absorption and spontaneous emission of heavily doped GaAs. J. Appl. Phys. 47, 631–643 (1976).

    Article  Google Scholar 

  47. Jiang, C. S. et al. Direct evidence of a buried homojunction in Cu(In,Ga)Se2 solar cells. Appl. Phys. Lett. 82, 127–129 (2003).

    Article  Google Scholar 

  48. Romeo, A. et al. Development of thin-film Cu(In,Ga)Se2 and CdTe solar cells. Prog. Photovolt. Res. Appl. 12, 93–111 (2004).

    Article  Google Scholar 

  49. Bertran, E., Lousa, A., Varela, M., Garciacuenca, M. V. & Morenza, J. L. Optical properties of indium doped CdS thin films. Sol. Energy Mater. 17, 55–64 (1988).

    Article  Google Scholar 

  50. Dhere, N. G., Moutinho, H. R. & Dhere, R. G. Morphology and electrical properties of In doped CdS thin films. J. Vac. Sci. Technol. A 5, 1956–1959 (1987).

    Article  Google Scholar 

  51. Metzger, W. K., Romero, M. J., Dippo, P. & Young, M. Characterizing recombination in CdTe solar cells with time-resolved photoluminescence. In Conference Record of the 2006 IEEE 4th World Conference on Photovoltaic Energy Conversion Vol. 1, 372–375 (IEEE, 2006).

    Google Scholar 

  52. Gloeckler, M., Fahrenbruch, A. L. & Sites, J. R. Numerical modeling of CIGS and CdTe solar cells: setting the baseline. In Proc. 3rd World Conference on Photovoltaic Energy Conversion, 2003 Vol. 1, 491–494 (IEEE, 2003).

    Google Scholar 

Download references

Acknowledgements

The work at NREL and Washington State University is supported by the US Department of Energy (DOE), Office of Energy Efficiency and Renewable Energy, under Contract No. DE-AC36-08GO28308. This research was supported, in part, by Oak Ridge National Laboratory’s Center for Nanophase Materials Sciences, where part of the TEM work was performed, which is sponsored by the Scientific User Facilities Division, Office of Basic Energy Sciences, DOE, in collaboration with R. R. Unocic. Other parts of the TEM work were performed at the LeRoy Eyring Center for Solid State Science at Arizona State University in collaboration with T. Aoki. The X-ray diffraction experiments were performed at the University of Tennessee, Knoxville, using instruments procured through the general infrastructure grant of the DOE-Nuclear Energy University Program (DE-NE0000693).

Author information

Authors and Affiliations

  1. National Renewable Energy Laboratory, Golden, Colorado 80401, USA

    J. M. Burst, J. N. Duenow, D. S. Albin, E. Colegrove, M. O. Reese, J. A. Aguiar, C.-S. Jiang, M. M. Al-Jassim, D. Kuciauskas & W. K. Metzger

  2. Materials Science and Engineering, University of Tennessee, Knoxville, Tennessee 37996, USA

    M. K. Patel

  3. Center for Materials Research, Washington State University, Pullman, Washington 99164, USA

    S. Swain, T. Ablekim & K. G. Lynn

Authors
  1. J. M. Burst
    View author publications

    You can also search for this author in PubMed Google Scholar

  2. J. N. Duenow
    View author publications

    You can also search for this author in PubMed Google Scholar

  3. D. S. Albin
    View author publications

    You can also search for this author in PubMed Google Scholar

  4. E. Colegrove
    View author publications

    You can also search for this author in PubMed Google Scholar

  5. M. O. Reese
    View author publications

    You can also search for this author in PubMed Google Scholar

  6. J. A. Aguiar
    View author publications

    You can also search for this author in PubMed Google Scholar

  7. C.-S. Jiang
    View author publications

    You can also search for this author in PubMed Google Scholar

  8. M. K. Patel
    View author publications

    You can also search for this author in PubMed Google Scholar

  9. M. M. Al-Jassim
    View author publications

    You can also search for this author in PubMed Google Scholar

  10. D. Kuciauskas
    View author publications

    You can also search for this author in PubMed Google Scholar

  11. S. Swain
    View author publications

    You can also search for this author in PubMed Google Scholar

  12. T. Ablekim
    View author publications

    You can also search for this author in PubMed Google Scholar

  13. K. G. Lynn
    View author publications

    You can also search for this author in PubMed Google Scholar

  14. W. K. Metzger
    View author publications

    You can also search for this author in PubMed Google Scholar

Contributions

J.M.B., J.N.D., E.C. and D.S.A. established anion doping and fabricated devices. M.O.R. developed surface cleaning and passivation methods. J.A.A., M.K.P., C.-S.J. and M.M.A.-J. directed and executed aberration-corrected STEM, HAADF, EELS, AFM, SKPM, SEM and EDS. D.K. performed two-photon excitation time-correlated single-photon counting. S.S., T.A. and K.G.L. made crystals. W.K.M., J.N.D., D.S.A. and J.M.B. directed research. All authors discussed the results and contributed to the manuscript.

Corresponding author

Correspondence to W. K. Metzger.

Ethics declarations

Competing interests

The authors declare no competing financial interests.

Supplementary information

Supplementary Information

Supplementary Figures 1–2, Supplementary Tables 1–2. (PDF 586 kb)

Rights and permissions

Reprints and permissions

About this article

Check for updates. Verify currency and authenticity via CrossMark

Cite this article

Burst, J., Duenow, J., Albin, D. et al. CdTe solar cells with open-circuit voltage breaking the 1 V barrier. Nat Energy 1, 16015 (2016). https://doi.org/10.1038/nenergy.2016.15

Download citation

  • Received:

  • Accepted:

  • Published:

  • DOI: https://doi.org/10.1038/nenergy.2016.15

This article is cited by

Search

Advanced search

Quick links

Nature Briefing

Sign up for the Nature Briefing newsletter — what matters in science, free to your inbox daily.

Get the most important science stories of the day, free in your inbox. Sign up for Nature Briefing