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Improved performance of Ge‐alloyed CZTGeSSe thin‐film solar cells through control of elemental losses
Author(s) -
Hages Charles J.,
Levcenco Sergej,
Miskin Caleb K.,
Alsmeier Jan H.,
AbouRas Daniel,
Wilks Regan G.,
Bär Marcus,
Unold Thomas,
Agrawal Rakesh
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.2442
Subject(s) - materials science , thin film solar cell , thin film , band gap , nanocrystal , solar cell , energy conversion efficiency , optoelectronics , chemical engineering , analytical chemistry (journal) , nanotechnology , chemistry , chromatography , engineering
Nanocrystal‐based Cu 2 Zn(Sn y Ge 1‐y )(S x Se 4‐x ) (CZTGeSSe) thin‐film solar cell absorbers with tunable band gap have been prepared. Maximum solar‐conversion total area efficiencies of up to 9.4% are achieved with a Ge content of 30 at.%. Improved performance compared with similarly processed films of Cu 2 ZnSn(S x Se 4‐x ) (CZTSSe, 8.4% efficiency) is achieved through controlling Ge loss from the bulk of the absorber film during the high‐temperature selenization treatment, although some Ge loss from the absorber surface is still observed following this step. Despite limitations imposed by elemental losses present at the absorber surface, we find that Ge alloying leads to enhanced performance due to increased minority charge carrier lifetimes as well as reduced voltage‐dependent charge carrier collection. Copyright © 2013 John Wiley & Sons, Ltd.