Stability of CIGS Solar Cells and Component Materials Evaluated by a Step-Stress Accelerated Degradation Test Method: Preprint
Abstract
A step-stress accelerated degradation testing (SSADT) method was employed for the first time to evaluate the stability of CuInGaSe2 (CIGS) solar cells and device component materials in four Al-framed test structures encapsulated with an edge sealant and three kinds of backsheet or moisture barrier film for moisture ingress control. The SSADT exposure used a 15 degrees C and then a 15% relativehumidity (RH) increment step, beginning from 40 degrees C/40%RH (T/RH = 40/40) to 85 degrees C/70%RH (85/70) as of the moment. The voluminous data acquired and processed as of total DH = 3956 h with 85/70 = 704 h produced the following results. The best CIGS solar cells in sample Set-1 with a moisture-permeable TPT backsheet showed essentially identical I-V degradation trend regardless of theAl-doped ZnO (AZO) layer thickness ranging from standard 0.12 um to 0.50 um on the cells. No clear 'stepwise' feature in the I-V parameter degradation curves corresponding to the SSADT T/RH/time profile was observed. Irregularity in I-V performance degradation pattern was observed with some cells showing early degradation at low T/RH < 55/55 and some showing large Voc, FF, and efficiency degradation due to increased series Rs (ohm-cm2) at T/RH = 70/70. Results of (electrochemical)more »
- Authors:
- Publication Date:
- Research Org.:
- National Renewable Energy Lab. (NREL), Golden, CO (United States)
- Sponsoring Org.:
- USDOE Office of Energy Efficiency and Renewable Energy (EERE), Renewable Power Office. Solar Energy Technologies Office
- OSTI Identifier:
- 1060065
- Report Number(s):
- NREL/CP-5200-54187
Journal ID: ISSN 0277-786X
- DOE Contract Number:
- AC36-08GO28308
- Resource Type:
- Conference
- Resource Relation:
- Journal Volume: 8472; Conference: Presented at SPIE Optics + Photonics 2012, 12-16 August 2012, San Diego, California
- Country of Publication:
- United States
- Language:
- English
- Subject:
- 14 SOLAR ENERGY; 36 MATERIALS SCIENCE; step-stress accelerated degradation test (SSADT); encapsulated test structure; CIGS solar cells; Mo on SLG; Al-doped ZnO window layer; alni contact grid; damp heat stability; performance reliability
Citation Formats
Pern, F. John, and Noufi, Rommel. Stability of CIGS Solar Cells and Component Materials Evaluated by a Step-Stress Accelerated Degradation Test Method: Preprint. United States: N. p., 2012.
Web. doi:10.1117/12.930541.
Pern, F. John, & Noufi, Rommel. Stability of CIGS Solar Cells and Component Materials Evaluated by a Step-Stress Accelerated Degradation Test Method: Preprint. United States. https://doi.org/10.1117/12.930541
Pern, F. John, and Noufi, Rommel. 2012.
"Stability of CIGS Solar Cells and Component Materials Evaluated by a Step-Stress Accelerated Degradation Test Method: Preprint". United States. https://doi.org/10.1117/12.930541. https://www.osti.gov/servlets/purl/1060065.
@article{osti_1060065,
title = {Stability of CIGS Solar Cells and Component Materials Evaluated by a Step-Stress Accelerated Degradation Test Method: Preprint},
author = {Pern, F. John and Noufi, Rommel},
abstractNote = {A step-stress accelerated degradation testing (SSADT) method was employed for the first time to evaluate the stability of CuInGaSe2 (CIGS) solar cells and device component materials in four Al-framed test structures encapsulated with an edge sealant and three kinds of backsheet or moisture barrier film for moisture ingress control. The SSADT exposure used a 15 degrees C and then a 15% relativehumidity (RH) increment step, beginning from 40 degrees C/40%RH (T/RH = 40/40) to 85 degrees C/70%RH (85/70) as of the moment. The voluminous data acquired and processed as of total DH = 3956 h with 85/70 = 704 h produced the following results. The best CIGS solar cells in sample Set-1 with a moisture-permeable TPT backsheet showed essentially identical I-V degradation trend regardless of theAl-doped ZnO (AZO) layer thickness ranging from standard 0.12 um to 0.50 um on the cells. No clear 'stepwise' feature in the I-V parameter degradation curves corresponding to the SSADT T/RH/time profile was observed. Irregularity in I-V performance degradation pattern was observed with some cells showing early degradation at low T/RH < 55/55 and some showing large Voc, FF, and efficiency degradation due to increased series Rs (ohm-cm2) at T/RH = 70/70. Results of (electrochemical) impedance spectroscopy (ECIS) analysis indicate degradation of the CIGS solar cells corresponded to increased series resistance Rs (ohm) and degraded parallel (minority carrier diffusion/recombination) resistance Rp, capacitance C, overall time constant Rp*C, and 'capacitor quality' factor (CPE-P), whic were related to the cells' p-n junction properties. Heating at 85/70 appeared to benefit the CIGS solar cells as indicated by the largely recovered CPE-P factor. Device component materials, Mo on soda lime glass (Mo/SLG), bilayer ZnO (BZO), AlNi grid contact, and CdS/CIGS/Mo/SLG in test structures with TPT showed notable to significant degradation at T/RH = 70/70. At T/RH = 85/70, substantial blistering of BZO layers on CIGS cell pieces was observed that was not seen on BZO/glass, and a CdS/CIGS sample displayed a small darkening and then flaking feature. Additionally, standard AlNi grid contact was less stable than thin Ni grid contact at T/RH = 70/70. The edge sealant and moisture-blocking films were effective to block moisture ingress, as evidenced by the good stability of most CIGS solar cells and device components at T/RH = 85/70 for 704 h, and by preservation of the initial blue color on the RH indicator strips. The SSADT experiment is ongoing to be completed at T/RH = 85/85.},
doi = {10.1117/12.930541},
url = {https://www.osti.gov/biblio/1060065},
journal = {},
issn = {0277-786X},
number = ,
volume = 8472,
place = {United States},
year = {Mon Oct 01 00:00:00 EDT 2012},
month = {Mon Oct 01 00:00:00 EDT 2012}
}