Photoconductive CdS: how does it Affect CdTe/CdS Solar Cell Performance?

Abstract

Photoconductive CdS (PC-CdS) in CdS/CdTe solar cells from five different sources is investigated using spectral sensitization of apparent quantum efficiency (AQE) and J-V analysis. Red bias light significantly enhances the blue AQE, commonly leading to AQE>1 below 550 nm, and blue bias light enhances the red AQE, but to a much smaller extent. These enhancements are more pronounced with increasing forward bias, after stress and in devices with intentionally Cu-doped CdS. This behavior is observed to some degree in all devices with CdS, but is absent in cells without CdS. These effects are consistent with blue light, either ac monochromatic or dc bias, increasing the CdS conductivity. This causes an increase in the field and depletion width in the CdTe to maintain balanced space charge, leading to increased collection of carriers from the CdTe. The CdS conductivity modulation can also change the AQE due to a change in equivalent circuit resistance. Analysis of J-V data measured with white, blue, red or no light indicates little dependence of series resistance or diode quality factor on the illumination spectrum. Thus, the PC-CdS resistance has little effect on the solar cell J-V performance, but does influence AQE.

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References

  1. 1.

    A. Rothwarf, Solar Cells 2, 115–1140 (1980).

    CAS  Article  Google Scholar 

  2. 2.

    A. Fahrenbruch, R. Bube, “Fundamental of Solar Cells”, Academic Press, New York Chapter 10 (1983).

    Google Scholar 

  3. 3.

    S. Asher, F. Hassoon, T. Gessert, M. Young, P. Sheldon, J. Hiltner, J. Sites, Proc. 28th IEEE Photovoltaic Spec. Conf., 478–482 (2000).

  4. 4.

    I. Visoly-Fisher, K. D. Dobson, J. Nair, E. Bezalel, G. Hodes and D. Cahen, Adv. Functional Materials 13, 289 – 299 (2003).

    CAS  Article  Google Scholar 

  5. 5.

    G. Agostinelli, D. Batzner, E. Dunlop, Proc. 17th Euro. Photovoltaic Solar Energy Conf., 1254–1257 (2001).

  6. 6.

    M. Kontges et al., Thin Solid Films 403–404, 280–286 (2002).

    CAS  Article  Google Scholar 

  7. 7.

    G. Agostinelli, D. Batzner, M. Burgelman, Proc. 29th IEEE Photovoltaic Spec. Conf., 744–747 (2002).

  8. 8.

    S. Hegedus, IEEE Trans. Electron Devices ED-31, 629–633 (1984).

  9. 9.

    J. Hou, S. Fonash, Appl. Phys. Lett. 61, 186–188 (1992).

    CAS  Article  Google Scholar 

  10. 10.

    P. Chatterjee, J. Appl. Phys. 75 1093–1097 (1993).

    Article  Google Scholar 

  11. 11.

    J. Phillips, M. Roy, Proc. 20th IEEE Photovoltaic Spec. Conf., 1614–1618 (1988).

  12. 12.

    J. Sites, H. Tavakolian, R. Sasala, Solar Cells 29, 39–48 (1990).

    CAS  Article  Google Scholar 

Download references

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Correspondence to S. Hegedus.

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Hegedus, S., Ryan, D., Dobson, K. et al. Photoconductive CdS: how does it Affect CdTe/CdS Solar Cell Performance?. MRS Online Proceedings Library 763, 95 (2002). https://doi.org/10.1557/PROC-763-B9.5

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