Effects of anion and cation doping on the thermoelectric properties of n-type PbS

The PbClxS1-x and Pb1-xBixS (x  = 0-0.05) bulks were fabricated with a facile method of hydrothermal synthesis and microwave sintering, and the effect of anionic and cationic donors on the thermoelectric performance of PbS was investigated. Although Cl− and Bi3+ both effectively improved the thermoelectric properties of n-type PbS, more excellent thermoelectric performance was obtained from Cl− doped samples because of higher electrical property and lower thermal conductivity at higher temperature (T  > 600 K). The thermoelectric figure of merit (ZT) reaches 1.04 for PbCl0.015S0.985 at 800 K and increases with temperature increasing without sign of saturation, which is probably the highest value ever reported for single-phase polycrystalline n-type PbS. The results also indicate that the hydrothermal synthesis and microwave sintering can realize anion doping as well as cation doping for n-type PbS at low cost, and PbS should be a robust alternative for PbTe thermoelectric materials.