Enhancement of thermoelectric performance of Cu1.98Se by Pb doping

Abstract

Potassium-doped Cu2Se compounds were fabricated using a combined process of hydrothermal synthesis and hot-pressed sintering. The effects of potassium doping on the thermoelectric properties were studied. Compared with the K-free sample, the Seebeck coefficients and the resistivity of K-doped samples increase. This is due to the annihilation of the intrinsic holes with the external electrons introduced by K doping in Cu2Se, which eventually leads to the decrease of the hole concentration. Especially, some micro-pores are introduced by K doping, together with reduced carrier concentration that result in low thermal conductivity. Finally, for the nominal component Cu1.97K0.03Se (EPMA measured component Cu1.9891K0.0108Se), the peak value of ZT reaches 1.19 at 773 K, which is 47% larger than that of pure Cu2Se (ZTmax = 0.81).