Hostname: page-component-78c5997874-4rdpn Total loading time: 0 Render date: 2024-11-10T10:30:00.686Z Has data issue: false hasContentIssue false
  • English
  • Français

How do Buffer Layers Affect Solar Cell Performance and Solar Cell Stability?

Published online by Cambridge University Press:  21 March 2011

Bolko von Roedern
Bolko von Roedern*
Affiliation:
National Renewable Energy Laboratory (NREL) 1617 Cole Blvd., Golden, CO 80401-3393, U.S.A
Get access

Abstract

Buffer layers are commonly used in the optimization of thin-film solar cells. For CuInSe2-and CdTe-based solar cells, multilayer transparent conductors (TCOs, e.g., ZnO or SnO2) are generally used in conjunction with a CdS heterojunction layer. Optimum cell performance is usually found when the TCO layer in contact with the CdS is very resistive or almost insulating. In addition to affecting the open-circuit voltage of a cell, it is commonly reported that buffer layers affect stress-induced degradation and transient phenomena in CdTe- and CuInSe2-based solar cells. In amorphous silicon solar cells, light-induced degradation has a recoverable and a nonrecoverable component too, and the details of the mechanism may depend on the p-type contact layer. Because of the similarity of transients and degradation in dissimilar material systems, it is suggested that degradation and recovery are driven by carriers rather than by diffusing atomic species. The question that must be addressed is why, not how, species diffuse and atomic configurations relax differently in the presence of excess carriers. In this paper, I suggest that the operating conditions of a cell can change the carrier transport properties. Often, excess carriers may enhance the conductance in localized regions (“filaments”) and buffer layers; limiting current flow into such filaments may therefore control the rate and amount of degradation (or recovery).

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 668: Symposium H – II-IV Compound Semiconductor Photovoltaic Materials , 2001 , H6.9
Copyright
Copyright © Materials Research Society 2001

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

REFERENCES

1. Roedern, B. von, Proceedings of the 12th European Photovoltaic Solar Energy Conference (H.S. Stephens & Associates, publishers), (1994), pp. 1354–1358.Google Scholar
2. Shklovskii, B.I. and Efros, A.L., Electronic Properties of Doped Semiconductors, Springer-Verlag (Berlin, New York) 1984, (Springer Series in Solid-State Sciences, vol. 45, see p.310).Google Scholar
3. Roedern, B. von and Bauer, G.H., Mat. Res. Soc. Symp. Proc. Vol. 557 (1999), 761.Google Scholar
4. Harju, R., Karpov, V.G., Grecu, D., and Dorer, G., J. Appl. Phys. 88 (2000), 1794 Google Scholar
5. Cueto, J. del and Roedern, B. von, Progress in Photovoltaics: Research and Applications 7, 101, (1999)Google Scholar
6. Mahon, T.J. Mc and Bennett, M.S., Mat. Res. Soc. Symp. Proc. Vol. 258, (1992), p. 941.Google Scholar
7. Kaydanov, V.I. and Ohno, T.R., “Process Development and Basic Studies of Electrochemically Deposited CdT-Based Solar Cells,” Annual Technical Report, Phase I, NREL/SR-520-28762, (2000).Google Scholar
8. Overhof, H., Mat. Res. Soc. Symp. Proc. Vol. 258, (1992), p. 681.Google Scholar
9. Osborne, I.S., Hajto, J., Snell, A.J., LeComber, P.G., and Owen, A.E., Mat. Res. Soc. Symp. Proc. Vol.258, (1992), p. 1169.Google Scholar
10.This MRS Spring Meeting, Paper A15.2 by Luysberg, M., Scholten, C., Houben, L., Vetterl, O., Carius, R., and Finger, F..Google Scholar
11.Figure 2 of reference 3 clearly demonstrates how a mobility or a diffusion length that is too large will degrade VOC.Google Scholar