Degradation of ZnO window layer for CIGS by damp-heat exposure preprint /
The reliability of ZnO-based window layer for CuInGaSe2 (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 a...
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| Format: | Government Document Electronic eBook |
| Language: | English |
| Published: |
Golden, CO :
National Renewable Energy Laboratory,
[2008]
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| Series: | Conference paper (National Renewable Energy Laboratory (U.S.)) ;
520-42792. |
| Subjects: | |
| Online Access: | CONNECT CONNECT |
| Summary: | The reliability of ZnO-based window layer for CuInGaSe2 (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. 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)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. |
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| Item Description: | Title from title screen (viewed on Aug. 22, 2008). "To be presented at 2008 SPIE PV Reliability Symposium, San Diego, California, August 10-14, 2008." "August 2008." |
| Physical Description: | 14 p. : digital, PDF file. |
| Format: | Mode of access: Internet from the NREL web site. Address as of 6/5/09: http://www.nrel.gov/docs/fy08osti/42792.pdf ; current access available via PURL. |
