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Failure analysis of Cu(In,Ga)Se 2 photovoltaic modules: degradation mechanism of Cu(In,Ga)Se 2 solar cells under harsh environmental conditions
Author(s) -
Lee DongWon,
Cho WonJu,
Song JunKwang,
Kwon OhYun,
Lee WonHee,
Park ChiHong,
Park KyungEun,
Lee Heesoo,
Kim YongNam
Publication year - 2015
Publication title -
progress in photovoltaics: research and applications
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.286
H-Index - 131
eISSN - 1099-159X
pISSN - 1062-7995
DOI - 10.1002/pip.2497
Subject(s) - copper indium gallium selenide solar cells , degradation (telecommunications) , adsorption , materials science , layer (electronics) , x ray photoelectron spectroscopy , zinc , solar cell , oxygen , oxide , chemical engineering , nuclear chemistry , chemistry , metallurgy , nanotechnology , organic chemistry , optoelectronics , telecommunications , computer science , engineering
High‐temperature‐induced and humidity‐induced degradation behaviors were investigated through the failure analysis of encapsulated Cu(In,Ga)Se 2 (CIGS) modules and non‐encapsulated CIGS cells. After being exposed to high temperature (85 °C) for 1000 h, the efficiency loss of CIGS modules and the resistivities of the aluminum‐doped zinc oxide (AZO) layer, CIGS layer, and Mo layer were slightly increased. After damp heat (DH) testing (85 °C/85% RH), the efficiency of some modules decreased significantly accompanied by discoloration, and in these areas, the resistivity of the AZO layers increased markedly. The causes of degradation of CIGS cells after high temperature and DH tests were suggested through X‐ray photoelectron spectroscopy analysis. The high‐temperature‐induced degradation behaviors were revealed to be increases in series resistance of the CIGS cells, due to the adsorption of oxygen on the AZO, CIGS, and Mo layers. The degradation behavior after DH (85 °C/85% RH) exposure was caused by the adsorption of oxygen, as well as the generation of Zn(OH) 2 due to water molecules. In particular, the humidity‐induced degradation behavior in discolored CIGS modules was ascribed to the generation of Zn(OH) 2 and carboxylic acids in the AZO layer, due to a chemical reaction between the AZO, ethylene‐vinyl acetate copolymer, and water. Copyright © 2014 John Wiley & Sons, Ltd.