Size effect enhanced thermoelectric properties of nanoscale Cu2-xSe

As a promising thermoelectric material, copper selenides have attracted the interest of researchers owing to their low cost, abundance in earth, environmental friendliness, and low thermal conductivity . In this study, copper selenide (Cu 2-x Se) powders with controllable sizes from nanoscale to mesoscale were obtained by a facile one-pot solvothermal method. After treatment with spark plasma sintering , the nanoscale Cu 2-x Se pellets exhibited excellent thermoelectric properties such as sharply reduced thermal conductivity and enhanced Seebeck coefficient as well as a suppressed electrical conductivity . The figure of merit ( ZT ) of the nanoscale Cu 2-x Se reached up to ∼1.51 at 873 K, which is about 2.67 times higher than that of the meso-Cu 2-x Se. This study confirms that thermoelectric properties can be enhanced by the size effect.