Highly enhanced thermoelectric properties of Cu1.8S by introducing PbS

Abstract Digenite (Cu 1.8 S) has attracted extensive attention as candidate for use in thermoelectric applications due to its low-cost, low-toxicity characteristics, but the thermoelectric (TE) property is still not good. In this work, PbS was used for improving TE properties of polycrystalline Cu 1.8 S bulk. Cu 1.8 S+  x wt% PbS ( x  = 0, 0.5, 1, 2, 3) bulk samples were fabricated via mechanical alloying (MA) and spark plasma sintering (SPS) techniques. The effects of adding PbS on the TE performance of Cu 1.8 S were investigated in detail at the temperature between 323 K and 773 K. According to the results, introducing PbS is an efficient approach for optimizing the TE properties of Cu 1.8 S, which is mainly due to the maintained electrical transport properties by the regulated hole carrier concentration and the modified band structure, as well as the reduced the thermal conductivity by the generated point defect and additional interfaces. An optimum thermoelectric figure of merit ( ZT ) value of 1.1 was obtained at 773 K for the Cu 1.8 S sample with 2 wt% PbS, which is 2.2 times higher than that of the pristine Cu 1.8 S (0.49 at 773 K).