Enhanced thermoelectric properties of Cu2ZnSnSe4 with Ga-doping

Gallium doped Cu2ZnSnSe4 quaternary chalcogenides with and without excess Cu were synthesized by elemental reaction and densified using hot pressing in order to investigate their high temperature transport properties. The resistivity, rho, and Seebeck coefficient, S, for these materials decrease with increased Ga-doping while both mobility and effective mass increase with Ga doping. The power factor (S-2/rho) therefore increases with Ga-doping however the highest thermoelectric figure of merit (ZT = 0.39 at 700 K) was obtained for the composition that had the lowest thermal conductivity. Our results suggest an approach for optimizing the thermoelectric properties of these materials and are part of the continuing effort to explore different quaternary chalcogenide compositions and structure types, as this class of materials continues to be of interest for energy-related applications. (C) 2015 Elsevier B.V. All rights reserved.