Enhanced seebeck coefficient and low thermal conductivity of Cu2SexTe1-x solid solutions via minority carrier blocking and interfacial effects

Abstract

Abstract The investigation of state-of-the-art copper chalcogenides (Cu2-yX; X = S, Se or Te) based thermoelectric (TE) materials can direct to improve the performances of TE devices. Herein, we report the synthesis of Cu2SexTe1-x solid solutions prepared by two-step ball-milling method. The effect of Se concentration on their TE performance as a function of temperature, was investigated. XRD and HRTEM analyses confirmed the size reduction and the presence of amorphous regions with polycrystalline behavior of the samples. To evaluate their TE performance, as-prepared powder samples were cold-pressed and annealed at 773 K. The high figure of merit was obtained for Cu2Se0·7Te0.3 solid solution as 0.3 at 500 K due to the synergy of high Seebeck coefficient (174 μVK−1 at 500 K) and low thermal conductivity (1.16 Wm−1K−1 at 500 K). The high Seebeck coefficient with optimum carrier concentration and low thermal conductivity was achieved due to wide range of phonon scattering. The results suggested that, Cu2SexTe1-x solid solutions were efficient for low grade (300–500 K) waste heat recovery.