Optical conductivity of highly mismatched GaP alloys

Abstract

Highly mismatched alloys are promising for applications to intermediate-band (IB) solar cells. Here, we report first-principles prediction of intermediate bands in GaP on the basis of hybrid-density-functional theory, which enables to handle large supercells including defects with much better accuracy than semilocal functionals. Calculated optical conductivity reveals that the intermediate states due to co-doped Mg and O have sufficiently high optical transition probability. The multiple gaps are robust against thermalization. Intermediate-band states become more delocalized by hybridization with phosphorus-vacancy states, increasing the optical transition probability.

Theoretical Photovoltaic Conversion Efficiencies of ZnSnP2, CdSnP2, and Zn1-xCdxSnP2Alloys

“…11,12) The HSE06 hybrid functional has been applied to a variety of semiconductors and shown to describe their atomic and electronic structures much better than local and semilocal functionals. 6,10,[13][14][15][16][17] A plane-wave cutoff energy of 400 eV and 8 Â 8 Â 4 k-point mesh were employed in the total-energy evaluation and geometry optimization for the chalcopyrite unit cells of ZnSnP 2 and CdSnP 2 . Electronic density of states and complex dielectric functions neglecting excitonic effects were calculated using a denser 16 Â 16 Â 8 k-point mesh.…”