Enhanced thermoelectric performance of n-type Bi2Se3 doped with Cu

The thermoelectric properties of Cu-doped CuxBi2Se3 (x = 0, 0.005, 0.010, 0.015 and 0.020) were investigated in the temperature range of 300 K to 590 K. The results indicate that, at 300 K, the thermal conductivity of moderately doped CuxBi2Se3 (x = 0.010 and 0.015) is by 30-50% lower than that of un-doped Bi2Se3, which is attributed to enhanced phonon scattering by the dopant. Though the absolute values of the thermopower are reduced by the doping, the electrical resistivity of the doped samples is strongly reduced (by ∼30% at 500 K, for instance), thus maintaining high values of power factor at both 300 K and 590 K, especially for samples with x ⩾ 0.01. As a result, the lightly doped compound Cu0.01Bi2Se3 exhibits the best thermoelectric performance, with a figure of merit, ZT, of 0.54 at 590 K. This is more than twice larger than that of the un-doped Bi2Se3 studied here, suggesting that proper Cu-doping in Bi2Se3 is a promising way to improve its thermoelectric performance.