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Control of the preferred orientations of Cu(In,Ga)Se 2 films and the photovoltaic conversion efficiency using a surface‐functionalized molybdenum back contact
Author(s) -
Yoon JuHeon,
Kim WonMok,
Park JongKeuk,
Baik YoungJoon,
Seong TaeYeon,
Jeong Jeunghyun
Publication year - 2014
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.2338
Subject(s) - copper indium gallium selenide solar cells , molybdenum , materials science , doping , bilayer , microstructure , thin film , layer (electronics) , chemical engineering , optoelectronics , nanotechnology , metallurgy , chemistry , membrane , biochemistry , engineering
The surface microstructures of molybdenum (Mo) back contacts were shown to play a crucial role in the preferred orientations of Cu(In,Ga)Se 2 (CIGS) films. The lower surface density of Mo tends to drive the growth of CIGS films toward favoring a (220)/(204) orientation, attributed to the higher likelihood of a MoSe 2 reaction. This work showed that the presence of a very thin layer on a Mo bilayer facilitated the tuning of the CIGS grain orientations from strongly favoring (112) to strongly favoring (220)/(204) without sacrificing the electrode conductivity. The efficiency of Na‐doped CIGS cells was increased toward decreasing Mo surface density, that is, increasing (220)/(204) CIGS orientation. Although slight changes in Na doping found between different Mo surface properties could contribute in part, the comparison with Na‐reduced CIGS cells showed that it was more likely due to the (220)/(204) orientation‐related enhancement of CdS/CIGS junction characteristics, which were possibly attributed to a favorable CdS reaction and a reduction in the defect metastabilities. Copyright © 2012 John Wiley & Sons, Ltd.