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Growth of Cu2ZnSnS4 absorber layer on flexible metallic substrates
for thin film solar cell applications*
Lutfi Ozyuzer
Department of Physics, Izmir Institute of Technology, Izmir, Turkey
[email protected]
Cu2ZnSnS4 (CZTS) is an alternative to Cu-In-Ga-Se based thin film solar cells due to
constituents of this semiconductor, copper, zinc, tin and sulfur, have the advantages of being
both abundant in the earth's crust and non-toxic. CZTS also has near ideal properties for solar
photovoltaics, as it is a very strong absorber and has a band gap of around 1.5 eV. In this study,
CZTS absorber layers were fabricated using a two-stage process. Sequentially deposited Cu-ZnSn thin film layers on metallic foils were annealed in an Ar + S2(g) atmosphere. We aimed to
investigate the role of flexible titanium and molybdenum foil substrates in the growth
mechanism of CZTS thin films. The Raman spectra and X-ray photoelectron spectroscopy
analyses of the sulfurized thin films revealed that, except for the presence of Sn-based secondary
phases, nearly pure CZTS thin films were obtained. Additionally, the intense and sharp X-ray
diffraction peak from the (112) plane provided evidence of good crystallinity. Electron
dispersive spectroscopy analysis indicated sufficient sulfur content but poor Zn atomic weight
percentage in the films. Absorption and band-gap energy analyses were carried out to confirm
the suitability of CZTS thin films as the absorber layer in solar cell applications. Hall effect
measurements showed the p-type semiconductor behavior of the CZTS samples. Moreover, the
back contact behavior of these metallic flexible substrates was investigated and compared. We
detected formation of cracks in the CZTS layer on the molybdenum foils, which indicates the
incompatibility of molybdenum’s thermal expansion coefficient with the CZTS structure. We
demonstrated the application of the magnetron sputtering technique for the fabrication of CZTS
thin films on titanium foils having lightweight, flexible properties and suitable for roll-to-roll
manufacturing for high throughput fabrication.1 Titanium foils are also cost competitive
compared to molybdenum foils.
*In collaboration with G. Aygun, S. Yazici, G. Akca, A. Cantas et al. This research was
supported in part by the TUBITAK (Scientific and Technical Council of Turkey) project number
114F341.
References
1. S. Yazici et al., Thin Solid Films, accepted, in press (2015).
Biography of Lutfi Ozyuzer
Lutfi Ozyuzer was born in Corum, Turkey in 1968. He received his
B.S. from physics engineering at Hacettepe University in 1991. He
obtained his M.S. in 1995 and received his Ph.D. in 1999 in
Physics from Illinois Institute of Technology, USA. He worked as
a postdoctoral research associate at Argonne National Laboratory
in 2000. He joined Izmir Institute of Technology (IZTECH) as an
Asst. Prof. in 2000. He received Young Investigators Award of
Turkish Academy of Sciences in 2002, Encouragement Award of
Scientific and Technical Council of Turkey (TUBITAK) in 2006
and received Research Fellowship for Experienced Scientist
Award of Alexander von Humboldt Foundation in 2008. He
worked at University of Erlangen-Nurnberg, Germany 2008-2010
as a visiting professor. Now, he is a full professor of physics at
IZTECH. His research interest including Terahertz wave emission
from superconducting Bi2212, tunneling effect of Intrinsic
Josephson Junctions. He studies resistivity, magnetization,
thermoelectric power, critical current and x-ray diffraction
measurements on thin film, and bulk samples. Recently, he is also
studying novel thin film solar cells grown by magnetron sputtering
technique.
Representative publications:
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F. Turkoglu, H. Koseoglu, Y. Demirhan, L. Ozyuzer, S. Preu, S. Malzer, Y. Simsek, P.
Muller, T. Yamamoto and K. Kadowaki, Supercond. Sci. Technol. 25, 125004 (2012).
C. Kurter, L. Ozyuzer, T. Proslier, J. F. Zasadzinski, D. G. Hinks and K. E. Gray, Physical
Review B 81, 224518 (2010).
O. Tuna, Y. Selamet, G. Aygun and L. Ozyuzer, Journal of Physics D: Applied Physics 43,
055402 (2010).
L. Ozyuzer, Y. Simsek, H. Koseoglu et al., Supercond. Sci. Technol. 22, 114009 (2009).
L. Ozyuzer, A. E. Koshelev, C. Kurter et al., Science 318, 1291 (2007).
J. F. Zasadzinski, L. Ozyuzer, L. Coffey, K. E. Gray, D. G. Hinks, and C. Kendziora,
Physical Rev. Lett. 96, 017004 (2006).
J. F. Zasadzinski, L. Ozyuzer, N. Miyakawa, K.E. Gray, D. G. Hinks, C. Kendziora,
Physical Review Letters 87, 067005 (2001).
L. Ozyuzer, J. F. Zasadzinski, C. Kendziora, K. E. Gray, Phys. Rev. B 61, 3629 (2000).