Influence of Damp Heat on the Electrical, Optical, and Morphological Properties of Encapsulated CuInGaSe2 Devices

R. Sundaramoorthy, F. J. Pern, G. Teeter, Jian V. Li, M. Young, D. Kuciauskas, N. Call, F. Yan, B. To, S. Johnston, R. Noufi, T. A. Gessert

Research output: Contribution to conferencePaperpeer-review

4 Scopus Citations


CuInGaSe 2 (CIGS) devices, encapsulated with different backsheets having different water vapor transmission rates (WVTR), were exposed to damp heat (DH) at 85°C and 85% relative humidity (RH) and characterized periodically to understand junction degradation induced by moisture ingress. Performance degradation of the devices was primarily driven by an increase in series resistance within first 50 h of exposure, resulting in a decrease in fill factor and, accompanied loss in carrier concentration and widening of depletion width. Surface analysis of the devices after 700-h DH exposure showed the formation of Zn(OH) 2 from hydrolysis of the Al-doped ZnO (AZO) window layer by the moisture, which was detrimental to the collection of minority carriers. Minority carrier lifetimes observed for the CIGS devices using time resolved photoluminescence (TRPL) remained relatively long after DH exposure. By etching the DH-exposed devices and re-fabricating with new component layers, the performance of reworked devices improved significantly, further indicating that DH-induced degradation of the AZO layer and/or the CdS buffer was the primary performance-degrading factor.

Original languageAmerican English
Number of pages6
StatePublished - 2011
Event37th IEEE Photovoltaic Specialists Conference, PVSC 2011 - Seattle, WA, United States
Duration: 19 Jun 201124 Jun 2011


Conference37th IEEE Photovoltaic Specialists Conference, PVSC 2011
Country/TerritoryUnited States
CitySeattle, WA

Bibliographical note

See NREL/CP-5200-50841 for preprint

NREL Publication Number

  • NREL/CP-5200-55763


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