Room temperature aqueous-based synthesis of copper-doped lead sulfide nanoparticles for thermoelectric application

A versatile, scalable, room temperature and surfactant-free route for the synthesis of metal chalcogenide nanoparticles in aqueous solution is detailed here for the production of PbS and Cu-doped PbS nanoparticles. Subsequently, nanoparticles are annealed in a reducing atmosphere to remove surface oxide, and consolidated into dense polycrystalline materials by means of spark plasma sintering. By characterizing the transport properties of the sintered material, we observe the annealing step and the incorporation of Cu to play a key role in promoting the thermoelectric performance of PbS. The presence of Cu allows improving the electrical conductivity by increasing the charge carrier concentration and simultaneously maintaining a large charge carrier mobility, which overall translates into record power factors at ambient temperature, 2.3 mWm(-1)K(- 2). Simultaneously, the lattice thermal conductivity decreases with the introduction of Cu, leading to a record high ZT = 0.37 at room temperature and ZT = 1.22 at 773 K. Besides, a record average ZT(ave) = 0.76 is demonstrated in the temperature range 320-773 K for n-type Pb0.955Cu0.045S.

Automated summary

A versatile, scalable, room temperature and surfactant-free method for synthesizing metal chalcogenide nanoparticles in aqueous solution is presented, with a focus on the production of PbS and Cu-doped PbS nanoparticles. The annealing step and incorporation of Cu are found to play a key role in promoting the thermoelectric performance of PbS, with improved electrical conductivity and reduced lattice thermal conductivity resulting in record power factors and ZT values.