Optical Properties of Cu2ZnSn(SxSe1-x)(4) by First-Principles Calculations

• 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.

Ämnesord

NATURVETENSKAP  -- Fysik (hsv//swe)

NATURAL SCIENCES  -- Physical Sciences (hsv//eng)

Nyckelord

Cu2ZnSnS4 (CZTS)

dielectric function

electronic structure

optical properties

solar cell materials

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