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    Optical characterization of Cu2ZnSnS4 nanocrystals thin film
    (SPRINGER, 2016) Kisnisci, Z.; Ozel, F.; Yuksel, O. F.; Tugluoglu, N.
    Synthesis of nanostructured powders of tetragonal Cu2ZnSnS4 (CZTS) nanocrystals was carried out based on the hot-injection process. High-quality CZTS thin films were prepared by spin coating method onto the Corning 1737 glass substrates. CZTS nanoparticles were characterized using X-ray diffraction (XRD), small-angle X-ray scattering (SAXS), transmission electron microscopy (TEM) and high resolution TEM. It is observed that a good quality CZTS film can be obtained by spin deposition at room temperature. The optical properties of the film were studied using UV-visible spectra between 300 and 1000 nm wavelength range. The direct optical band gap of the film evolved as 1.49 eV. This value is close to the ideal band gap for highest theoretical conversion efficiency of solar cell. The optical absorption coefficients of the film between 300 and 1000 nm are found to be about 2 and 7.6 x 10(4) cm(-1), respectively. The optical dispersion parameters of the film were also determined by Wemple-DiDomenico single oscillator model.
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    Optical characterization of Cu2ZnSnSe4-xSx nanocrystals thin film
    (ELSEVIER SCIENCE SA, 2016) Yildirim, M.; Ozel, F.; Tugluoglu, N.; Yuksel, O. F.; Kus, M.
    Cu2ZnSnSe4-xSx (CZTSeS) nanocrystals have been shown to be a potential application for sustainable thin-film solar cell devices. In this paper, we have presented the growth of nanocrystals CZTSeS and their thin films applications successfully prepared on soda-lime glass substrates by using spin coating techniques. The CZTSeS nanocrystals have been synthesized by hot-injection method. In-depth characterization has indicated that pure stoichiometric CZTSeS nanocrystals with an average particle size mostly distributed between 15 and 20 nm have been formed. We have analyzed the optical transmission and reflection spectra of nanocrystal CZTSeS thin film. Optical band gap E-g and absorption coefficient (a) of thin film have been determined by standard optical analysis and also several optical parameters such as refractive index (n), extinction coefficient (k), the Urbach energy (E-U) and real and imaginary parts of dielectric constant (epsilon) have been calculated. Detailed characterization data including X-ray diffraction, surface morphology, cross section analysis, optical transmittance and reflectance spectroscopy have been presented in order to use in the performance of single-junction solar devices. Optical measurements have showed a band gap of 1.51 eV, which is optimal for a single-junction solar device. (C) 2016 Elsevier B.V. All rights reserved.