P 47 ISSRNS 2012: Abstracts / Synchrotron Radiation in Natural Science Vol. 11, No 1 – 2 (2012)
THERMAL EXPANSION OF CuInSe
2W. Paszkowicz1∗, R. Minikayev1, P. Piszora2, M. Knapp3, D. Trots4, and R. Bacewicz5
1Institute of Physics PAS, al. Lotnikow 32/46, 02–668 Warsaw, Poland
2Faculty of Chemistry, A. Mickiewicz University, ul. Grunwaldzka 6, 60–780 Poznan, Poland
3Karlsruhe Institute of Technology, KIT (Germany), IAM-ESS Institute for Applied Materials
— Energy Storage Systems, Karlsruhe, Germany
4Bayerisches Geoinstitut Universit¨at Bayreuth Universitaetsstrasse 30, D–95447 Bayreuth, Germany
5Institute of Physics, Warsaw Technical University, ul. Koszykowa 75, 00–662 Warsaw, Poland Keywords: CuInSe2, thermal expansion, lattice parameter
∗e-mail : paszk@ifpan.edu.pl
The CuSe2– In2Se3 phase diagram [1] includes several ternary compounds. The most known among them, copper indium diselenide, CuInSe2, (of chalcopyrite type, or, in a specially prepared nanocrystal form, of wurtzite type [2]) has been ex- tensively studies because of opportunity of its ap- plication as an efficient absorber in polycrystalline- thin-film solar cells. In this case, good efficiency can be achieved using an absorbing layer of several micrometers thickness, only. The reported energy conversion efficiency approaches 20% [3, 4]. Recent studies show its possible use as a nanocrystal ink [5]
in fabrication of dense absorber films.
Early studies on thermal expansion of CuInSe2
were limited to temperatures above 30 and 60 K for a and c lattice parameters, respectively [6], and, for both parameters, to 80 K [7]. In the present study, the thermal expansion coefficient for CuInSe2
are determined on the basis of the recently collected data [8] and compared with the existing literature data.
The crystals studied in this paper were grown at Warsaw University of Technology using the vertical Bridgman method without seed. The XRD mea- surements were carried out at a powder diffractome- ter at the B2 (Hasylab/DESY, Hamburg) beamline [9] using the Debye-Scherrer geometry. A diamond powder was used as internal wavelength calibrant.
Figure 1 : Volume thermal expansion coefficients of CuInSe2 (solid line). Literature data for CuIn3Se5 [11]
are shown for comparison (dotted line).
A preliminary study performed at the same syn- chrotron beamline without such standard has shown that the lattice parameters determined in this way suffer from non-smooth temperature behaviour [10], pointing out the necessity of elimination of the wavelength fluctuations. This problem was solved using the above-mentioned calibrant.
The obtained results of X-ray diffraction exper- iments show, in qualitative agreement with those reported in Ref. [6], that there is a vanishing ten- dency of the CuInSe2thermal expansion at the low- est temperatures; the values of the thermal expan- sion coefficients tend to be slightly negative below 50 K.
References
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ISSRNS 2012: Abstracts / Synchrotron Radiation in Natural Science Vol. 11, No 1 – 2 (2012) P 47 [8] W. Paszkowicz, P. Piszora, R. Minikayev, M. Knapp,
D. Trots, F. Firszt, R. Bacewicz, “Evolution of CuInSe2 lattice parameters in a broad temperature range,” Z. Kristalllogr. Proc. 1 (2011) 373 – 378.
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