Degradation of ZnO-Based Window Layers for Thin-Film CIGS by Accelerated Stress Exposures
The reliability of ZnO-based window layer for CuInGaSe{sub 2} (CIGS) solar cells was investigated. Samples of RF magnetron-sputtered, single-layer intrinsic and Al-doped ZnO and their combined bilayer on glass substrates were exposed in a weatherometer (WOM) and damp heat (DH) conditions with or without acetic acid vapor. Some preliminary samples of single-layer Al-doped Zn{sub 1-x}Mg{sub x}O (ZMO) alloy, a potential replacement for Al:ZnO with a wider bandgap, were also evaluated in the DH. The Al-doped ZnO and ZMO films showed irreversible loss in the conducting properties, free carrier mobility, and characteristic absorption band feature after <500-h DH exposure, with the originally clear transparent films turned into white hazy insulating films and the degradation rate follows the trend of (DH + acetic acid) > DH > WOM. The degradation rate was also reduced by higher film thickness, higher deposition substrate temperature, and dry-out intervals. The results of X-ray diffraction analysis indicate that the ZnO-based films underwent structural degeneration by losing their highly (002) preferential orientation with possible transformation from hexagonal into cubic and formation of Zn(OH){sub 2}. Periodic optical micro-imaging observations suggested a temporal process that involves initial hydrolysis of the oxides at sporadic weak spots, swelling and popping of the hydrolyzed spots due to volume increase, segregation of hydrolyzed regions causing discontinuity of electrical path, hydrolysis of the oxide-glass interface, and finally, formation of insulating oxides/hydroxides with visible delamination over larger areas.
- Research Organization:
- National Renewable Energy Laboratory (NREL), Golden, CO.
- Sponsoring Organization:
- USDOE Office of Solar Energy Technologies Program
- DOE Contract Number:
- AC36-08GO28308
- OSTI ID:
- 1022344
- Country of Publication:
- United States
- Language:
- English
Similar Records
Damp-Heat Induced Degradation of Transparent Conducting Oxides for Thin-Film Solar Cells: Preprint
Influence of Damp Heat on the Electrical, Optical, and Morphological Properties of Encapsulated CuInGaSe2 Devices
Effect of aluminium doping on structural and optical properties of ZnO thin films by sol-gel method
Conference
·
Thu May 01 00:00:00 EDT 2008
·
OSTI ID:929591
Influence of Damp Heat on the Electrical, Optical, and Morphological Properties of Encapsulated CuInGaSe2 Devices
Conference
·
Fri Dec 31 23:00:00 EST 2010
·
OSTI ID:1049640
Effect of aluminium doping on structural and optical properties of ZnO thin films by sol-gel method
Journal Article
·
Wed Jun 24 00:00:00 EDT 2015
· AIP Conference Proceedings
·
OSTI ID:22490404