Enhanced Thermoelectric Performance of Cu(2)Se via Nanostructure and Compositional Gradient

Forming co-alloying solid solutions has long been considered as an effective strategy for improving thermoelectric performance. Herein, the dense Cu(2−x)(MnFeNi)(x)Se (x = 0–0.09) with intrinsically low thermal conductivity was prepared by a melting-ball milling-hot pressing process. The influences of nanostructure and compositional gradient on the microstructure and thermoelectric properties of Cu(2)Se were evaluated. It was found that the thermal conductivity decreased from 1.54 Wm(−1)K(−1) to 0.64 Wm(−1)K(−1) at 300 K via the phonon scattering mechanisms caused by atomic disorder and nano defects. The maximum zT value for the Cu(1.91)(MnFeNi)(0.09)Se sample was 1.08 at 750 K, which was about 27% higher than that of a pristine sample.