Theoretical investigation on thermoelectric properties of Cu-based chalcopyrite compounds

Abstract

Cu-based materials are potential candidates for commercial thermoelectric materials due to their abundance, nontoxicity, and high performance. We incorporate the multiband Boltzmann transport equations with first-principles calculations to theoretically investigate the thermoelectric properties of Cu-based chalcopyrite compounds. As a demonstration of our method, the thermoelectric properties of quaternary compounds ${\mathrm{Cu}}_{2}{\mathrm{ZnSnX}}_{4}$ (X = S, Se) and ternary compounds ${\mathrm{CuBTe}}_{2}$ (B = Ga, In) are studied. We systematically calculate the electrical conductivity, the Seebeck coefficient, and the power factor of the four materials above based on parameters obtained from first-principles calculations and using several other fitting parameters. For quaternary compounds, our results reveal that ${\mathrm{Cu}}_{2}{\mathrm{ZnSnSe}}_{4}$ is better than ${\mathrm{Cu}}_{2}{\mathrm{ZnSnS}}_{4}$ and its optimal hole concentration is around $5\ifmmode\times\else\texttimes\fi{}{10}^{19}\phantom{\rule{0.28em}{0ex}}{\mathrm{cm}}^{\ensuremath{-}3}$ with the peak power factor 4.7 $\ensuremath{\mu}{\mathrm{W}/\mathrm{cm}\phantom{\rule{0.16em}{0ex}}\mathrm{K}}^{2}$ at 600 K. For ternary compounds, we find that their optimal hole concentrations are around $1\ifmmode\times\else\texttimes\fi{}{10}^{20}\phantom{\rule{0.16em}{0ex}}{\mathrm{cm}}^{\ensuremath{-}3}$ with the peak power factors over 26 $\ensuremath{\mu}{\mathrm{W}/\mathrm{cm}\phantom{\rule{0.16em}{0ex}}\mathrm{K}}^{2}$ at 800 K.