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Ternary and multinary Cu‐chalcogenide photovoltaic materials from CuInSe 2 to Cu 2 ZnSnS 4 and other compounds
Author(s) -
Wada Takahiro,
Nakamura Satoshi,
Maeda Tsuyoshi
Publication year - 2012
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.2183
Subject(s) - chalcogen , ternary operation , band gap , chalcogenide , thin film , czts , semiconductor , materials science , chemistry , optoelectronics , crystallography , nanotechnology , computer science , programming language
ABSTRACT Such ternary and multinary copper chalcogenides (TMCC) as CuInSe 2 (CIS) and Cu 2 ZnSnS 4 are suitable as absorber materials for thin‐film solar cells. The valence band consists of Cu 3d and chalcogen p orbitals, and the conduction band consists of III (In) n s or IV (Sn) n s and chalcogen p orbitals. The band structure characteristics of TMCC differ from those of conventional II–VI compounds. The valence band maximum is higher, and the bandgap is narrower than II–VI compounds. Therefore, the electrons in the valence band of TMCC are easily removed, and TMCC tends to be a p‐type semiconductor. This common characteristic of TMCC is one reason that it is suitable as an absorber material in thin‐film solar cells. In CIS, two kinds of chemical bond, Cu–Se and In–Se, exist. Among them, the In–Se bond is much stronger than the Cu–Se bond. This characteristic is advantageous for the “three‐stage process” of high‐quality CIS thin films used in solar cells. However, the characteristics of the other TMCC are not the same as those of CIS. A deposition process of high‐quality TMCC thin films that exploits the characteristics of chemical bonding in TMCC should be developed. Copyright © 2012 John Wiley & Sons, Ltd.