To improve the thermoelectric properties of Cu2GeSe3 via GeSe compensatory compositing strategy

Abstract

The potential thermoelectric Cu2GeSe3 is limited by the unfavorable exorbitant electrical conductivity and the subsequent high electrical thermal conductivity. In this regard, we highlight a compensatory compositing strategy to synergistically optimize its thermoelectric properties by adding GeSe second-phase. Experimental results demonstrated that the GeSe additive compensated the carrier concentration and mobility to some extent, which suppressed the exorbitant electrical conductivity and led to much reduced electrical thermal conductivity and the final low thermal conductivity in (GeSe)x(Cu2GeSe3)1–x composites. Meanwhile, due to the decreased carrier mobility, the GeSe additive could also increase the effective mass of the Cu2GeSe3 matrix, which significantly enhanced the Seebeck coefficient and power factor. Finally, with the synergistically optimized electrical and thermal transport properties of Cu2GeSe3 via GeSe addition, the final figure-of-merit ZT values of composites were significantly improved. The peak ZT of the average of three times trials of 0.49 was achieved at 723 K for (GeSe)0.02(Cu2GeSe3)0.98 composite, which was 188% higher than its pristine counterpart.