Hostname: page-component-78c5997874-m6dg7 Total loading time: 0 Render date: 2024-11-04T17:50:24.821Z Has data issue: false hasContentIssue false
  • English
  • Français

Temperature-dependent Degradation Modes in CdS/CdTe Devices

Published online by Cambridge University Press:  01 February 2011

David Albin ,
Samuel H Demtsu ,
Anna M Duda  and
Wyatt K Metzger
David Albin
Affiliation:
[email protected], National Renewable Energy Laboratory, National Center for Photovoltaics, 1617 Cole Blvd, MS 3219, Golden, CO, 80401, United States, 303-384-6550
Samuel H Demtsu
Affiliation:
[email protected], Solopower, Inc, 1635 McCandless Drive, Milpitas, CA, 95035, United States
Anna M Duda
Affiliation:
[email protected], National Renewable Energy Laboratory, 1617 Cole Blvd, Golden, CO, 80401, United States
Wyatt K Metzger
Affiliation:
[email protected], National Renewable Energy Laboratory, 1617 Cole Blvd, Golden, CO, 80401, United States
Get access

Abstract

A set of 24 identically made CdS/CdTe devices were subjected to accelerated lifetime testing (ALT) under open-circuit bias, 1 sun illumination, and temperatures of 60, 80, 100, and 120 °C. A total of 6 identical devices were tested for statistical purposes at each temperature. Current density-voltage (JV) measurements were made on stressed cells for up to 2000+ hours. Device performance parameters were calculated as a function of temperature and stress time using discrete element circuit models. Forward current behavior was represented by two parallel diodes to simulate recombination currents in the quasi-neutral (QNR) and space-charge (SCR) regions. Backcontact behavior was studied using a parallel combination blocking diode and shunt conductance. A systematic pattern of degradation was apparent with increased stress temperature. At 60 °C, degradation associated with the CdTe/backcontact dominates. At temperatures above 80 °C, greater losses in fill factor (FF) and open-circuit voltage (Voc) were observed. Recombination current modeling of JV data attributes this to increased space-charge recombination. Calculated diffusion lengths based upon an Arrhenius-derived activation energy of 0.63 eV in this temperature-range suggests Cu diffusion into the SCR is mechanistically responsible for the observed increased recombination, and decreased Voc and FF. At lower temperatures (60 to 80 ºC), degradation was considerably slower with a measured activation energy of 2.9 eV.

Keywords

photovoltaicthin filmII-VI
Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 1012: Symposium Y – Thin-Film Compound Semiconductor Photovoltaics-2007 , 2007 , 1012-Y01-07
Copyright
Copyright © Materials Research Society 2007

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

1. Wu, X., Solar Energy 77 (2004) 803.Google Scholar
2. Visoly-Fisher, I., Dobson, K., Nair, J., Bezalel, E., Hodes, G., and Cahen, D., Adv. Funct. Mater. 13 (2003) 289.Google Scholar
3. Dobson, K., Visoly-Fisher, I., Hodes, G., and Cahen, D., Sol. Energy Mater. Sol. Cells 62 (2000) 295.Google Scholar
4. Hegedus, S. and McCandless, B., Sol. Energy Mater. Sol. Cells 88 (2005) 75.Google Scholar
5. Nelson, W., Accelerated Testing – Statistical Models, Test Plans, and Data Analysis, John Wiley & Sons (1990).Google Scholar
6. Tetali, B., Viswanathan, V., Morel, D., Ferekides, C., Proc. 29th IEEE Photovoltaic Specialists Conference (2002) 600.Google Scholar
7. Barth, K., Enzenroth, R., and Sampath, W., Proc. 29th IEEE Photovoltaic Specialists Conference (2002).Google Scholar
8. Albin, D., Demtsu, S., and McMahon, T., Thin Solid Films 515 (2006) 2659.Google Scholar
9. Levi, D., Albin, D., King, D., Prog. Photovolt: Res. Appl. 8 (2000) 591.Google Scholar
10. Demtsu, S., Sites, J., Thin Solid Films 510 (2006) 320.Google Scholar
11. Demtsu, S., Albin, D., and Sites, J., IEEE – 4th World Conference on Photovoltaic Energy Conversion (2006) 523.Google Scholar
12. Woodbury, H. and Aven, M., J. Appl. Phys. 39 (1968) 5485.Google Scholar