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- Li, Shu-Yi, et al.
(författare)
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Optical properties of Cu2ZnSn(SxSe1-x)(4) solar absorbers : Spectroscopic ellipsometry and ab initio calculations
- 2017
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Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 110:2
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Tidskriftsartikel (refereegranskat)abstract
- Dielectric functions of Cu2ZnSn(SxSe1-x)(4) thin film absorbers with varied x were determined by spectroscopic ellipsometry and ab initio calculations. From the combination of experimental and theoretical studies, the fundamental interband transition energy E-0 (similar to 1-1.5 eV) and the next following transition energy E-1 (similar to 2-3 eV) were identified and found to blue-shift with increasing sulfur anion content, while keeping the energy separation E-1 - E-0 almost constant, similar to 1.4 eV from experiments, and 1 eV from theory. In addition, the average dielectric responses were found to decrease with sulfur anion content from both theoretical and experimental results. The Tauc optical bandgap value E-g determined on samples prepared on Mo and soda lime glass substrate showed a positive linear relationship between x and bandgap E-g. The bandgap bowing factor determined from the theoretical data is 0.09 eV. (C) 2017 Author(s).
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| 2. |
- Zamulko, Sergiy, et al.
(författare)
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Optical Properties of Cu2ZnSn(SxSe1-x)(4) by First-Principles Calculations
- 2018
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Ingår i: Physica Status Solidi (a) applications and materials science. - : Wiley-VCH Verlagsgesellschaft. - 1862-6300 .- 1862-6319. ; 215:17
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Tidskriftsartikel (refereegranskat)abstract
- Structural, electronic, and optical properties of Cu2ZnSn(SxSe1-x)(4) semiconductors are studied theoretically for different concentration of S and Se anions. The optical properties are calculated at three levels of theory, in the generalized gradient approximation (GGA), meta-GGA, and with a hybrid functional. The GGA and meta-GGA calculations are corrected with an on-site Coulomb U-d term. Lattice constants, dielectric constants, and band-gaps are found to vary almost linearly with the concentration of S. The authors also show that a dense sampling of the Brillouin zone is required to accurately account for the shape of the dielectric function, which is hard to attain with hybrid functionals. This issue is resolved with a recently developed kp based interpolation scheme, which allows us to compare results of the hybrid functional calculations on an equal footing with the GGA and meta-GGA results. We find that the hybrid functionals provide the overall best agreement with the experimental dielectric function.
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