Exploring the doping effects of copper on thermoelectric properties of lead selenide

In this work, we have explored the effect of dopant concentration (copper (Cu)) on the thermoelectric performance of Cu doped lead selenide (Pb1-xCuxSe (0 <= x <= 0.1)). With increasing the dopant concentration, sign inversion of majority charge carriers takes place for x >= 0.04 due to the donor behaviour of Cu in the P-type pristine PbSe. The room temperature Seebeck coefficients of Pb1-xCuxSe with x = 0.01, 0.02, 0.04, 0.06 and 0.08 are observed to be 233, 337, -473.7, -392.5 and -257.6 mu V K-1, respectively as compared to that of 186.4 mu V K-1 of the pristine PbSe. This increment in Seebeck coefficient is the result of low carrier concentration and is not related to the resonance states created by Cu dopant. At room temperature, the lattice thermal conductivity of pristine PbSe is 0.52 W m(-1) K-1 while for Cu doped PbSe, it varies from 0.8 to 1.1 W m(-1) K-1. Finally, with ZT of similar to 0.59 and power factor of similar to 700 at 500 K, Pb0.98Cu0.02Se exhibits the highest thermoelectric performance among the studied Pb1-xCuxSe systems. Owing to the high ZT and power factor, a single thermoelement of Pb0.98Cu0.02Se exhibits thermovoltage of >100 mV at a temperature gradient of 200 degrees C.