Please use this identifier to cite or link to this item: http://hdl.handle.net/10995/102134
Title: Influence of the copper content on the optical properties of CZTSe thin films
Authors: Yakushev, M. V.
Sulimov, M. A.
Márquez-Prieto, J.
Forbes, I.
Krustok, J.
Edwards, P. R.
Zhivulko, V. D.
Borodavchenko, O. M.
Mudryi, A. V.
Martin, R. W.
Issue Date: 2017
Publisher: Elsevier B.V.
Citation: Influence of the copper content on the optical properties of CZTSe thin films / M. V. Yakushev, M. A. Sulimov, J. Márquez-Prieto, et al. — DOI 10.1016/j.solmat.2017.04.022 // Solar Energy Materials and Solar Cells. — 2017. — Vol. 168. — P. 69-77.
Abstract: We present an optical spectroscopy study of Cu2ZnSnSe4 (CZTSe) thin films deposited on Mo/glass substrates. The [Cu]/[Zn+Sn] ratio in these films varies from nearly stoichiometric to strongly Cu deficient and Zn rich. Increasing Cu deficiency and Zn excess widens the bandgap Egdetermined using photoluminescence excitation (PLE) at 4.2 K, from 0.99 eV to 1.03 eV and blue shifts the dominant band in the photoluminescence (PL) spectra from 0.83 eV to 0.95 eV. The PL spectra of the near stoichiometric film reveal two bands: a dominant band centred at 0.83 eV and a lower intensity one at 0.93 eV. The temperature and excitation intensity dependence of the PL spectra help to identify the recombination mechanisms of the observed emission bands as free-to-bound: recombination of free electrons with holes localised at acceptors affected by randomly distributed potential fluctuations. Both the mean depth of such fluctuations, determined by analysing the shape of the dominant bands, and the broadening energy, estimated from the PLE spectra, become smaller with increasing Cu deficiency and Zn excess which also widens Eg due to an improved ordering of the Cu/Zn atoms. These changes in the elemental composition induce a significant blue shift of the PL bands exceeding the Eg widening. This is attributed to a change of the dominant acceptor for a shallow one, and is beneficial for the solar cell performance. Film regions with a higher degree of Cu/Zn ordering are present in the near stoichiometric film generating the second PL band at 0.93 eV. © 2017
Keywords: CU2ZNSNSE4
DEFECTS
OPTICAL SPECTROSCOPY
COPPER
COPPER COMPOUNDS
DEFECTS
MOLYBDENUM COMPOUNDS
OPTICAL PROPERTIES
PHOTOLUMINESCENCE
SELENIUM COMPOUNDS
TIN COMPOUNDS
ZINC
ZINC COMPOUNDS
CU2ZNSNSE4
ELEMENTAL COMPOSITIONS
OPTICAL SPECTROSCOPY
PHOTOLUMINESCENCE EXCITATION
PHOTOLUMINESCENCE SPECTRUM
POTENTIAL FLUCTUATIONS
RECOMBINATION MECHANISMS
SOLAR CELL PERFORMANCE
THIN FILMS
URI: http://hdl.handle.net/10995/102134
Access: info:eu-repo/semantics/openAccess
SCOPUS ID: 85018473617
PURE ID: 1816122
cd1c0049-322b-4ecb-84a8-35279b33fd8c
ISSN: 9270248
DOI: 10.1016/j.solmat.2017.04.022
Appears in Collections:Научные публикации, проиндексированные в SCOPUS и WoS CC

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