Enhanced thermoelectric performance of MnTe via Cu doping with optimized carrier concentration

Polycrystalline Mn1-xCuxTe (x = 0, 0.025, 0.05, 0.075) thermoelectric materials were prepared by a combined method of melt-quenching and hot press. The effect of Cu doping on the electrical resistivity, band gap, the Seebeck coefficient and thermal conductivity was investigated. The power factors of the Cu-doped samples increase greatly due to the decrease of electrical resistivity and the higher Seebeck coefficient in high temperatures. In addition, the thermal conductivities of the Cu-doped samples also reduce due to the extra phonon scattering from the point defects introduced by Cu doping. As a result, the thermoelectric performance of MnTe is greatly enhanced, and a maximum ZT value of ∼0.55 in the Mn0.925Cu0.075Te sample at 773 K is achieved, which is 35% greater than that of the pristine MnTe sample.