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Open questions after 20 years of CuInS 2 research
Author(s) -
Scheer Roland
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.2155
Subject(s) - heterojunction , conduction band , band gap , open circuit voltage , optoelectronics , buffer (optical fiber) , solar cell , saturation (graph theory) , materials science , interface (matter) , chemistry , voltage , electrical engineering , computer science , telecommunications , physics , electron , composite material , mathematics , quantum mechanics , combinatorics , capillary number , capillary action , engineering
ABSTRACT In the early 1990s, CuInS 2 thin film solar cells with >10% efficiency had been developed. Since then, they are limited by an open‐circuit voltage which is too low for the band gap of CuInS 2 . Recombination at the CdS/CuInS 2 interface was made responsible for this shortcoming. This was concluded from two experimental results: a conduction band cliff found at the buffer/absorber interface and activation energy of the saturation current being smaller than the absorber band gap energy. However, replacing the CdS buffer layer in the Mo/CuInS 2 /buffer/ZnO heterostructure solar cell with wide gap buffers did not lead to substantially higher V oc . Also the activation energy was unaltered. In this paper, we discuss interface and bulk aspects of CuInS 2 and Cu(In,Ga)S 2 cells, try to give a consistent picture and make suggestions for novel experiments. Copyright © 2012 John Wiley & Sons, Ltd.