Doping-mediated stabilization of copper vacancies to promote thermoelectric properties of Cu2−xS

PbS–Pb–CuxS Composites for Thermoelectric Application

“…Finally, to experimentally determine the effect of the metallic Pb and compare it with the effect of Cu x S domains, we produced and measured a PbS–Cu x S sample, free of metallic Pb, by blending PbS and covellite CuS nanoparticles . As detailed in our previous work, covellite CuS particles lose sulfur during the annealing process, evolving to Cu reach phases such as the tetragonal Cu 1.96 S and the monoclinic Cu 2 S phases (Figure S11), especially in a H 2 -containing atmosphere. , Thus, CuS particles are not able to reduce the PbS as occurring in the PbS + Cu blend. Thus, as expected, the annealed PbS + CuS blend displayed no sign of the presence of metallic Pb (Figure S12).…”

“…The aim of combining Cu with PbS was to control the charge carrier concentration of the base material PbS through charge carrier spillover from metallic Cu domains, which have a relatively low work function (4.7 eV). While Cu x S also displays low work functions (4.8 eV) and relatively large charge carrier concentrations, , we selected Cu instead of Cu x S because of the higher density of free charges in the metal. However, after a comprehensive analysis of the consolidated material, we observed the PbS + Cu blends to become PbS–Pb–Cu x S composites due to the partial reduction of the PbS to Pb and the concomitant oxidation of Cu to Cu x S. The redox process occurring during the annealing of the material under Ar + H 2 atmosphere was very convenient for the initial goal of the project because metallic Pb is also characterized by a high charge carrier density than Cu x S and at the same time shows an even lower work function (4.14 eV) than metallic Cu.…”

Two-dimensional copper based colloidal nanocrystals: synthesis and applications

“…12d). 163 Thus, stabilization of the Cu 1.8 S phase during annealing resulted in a high power factor and a high ZT of 2.03 at 880 K (Fig. 12e and f ).…”

“…Owing to the unique characteristics related to their structural features, copper-based 2D NCs have received a lot of interest in plasmonics, heterogeneous catalysis, thermoelectrics and metal-ion batteries. 28,63,141,150,162,163 2D nanostructures outperform 0D and 1D nanomaterials in architectural modification, charge separation, light harvesting and tunability. 7,164 Extensive research has been done to develop effective catalysts with 2D nanomaterials, inspired by the unique optical, electronic properties and high surface area.…”

“…In recent times, the Cu-based chalcogenides having reached ZT values >2 attracted immense attention as viable TE materials. 163,167,185 The copper based binary chalcogenides, especially Cu 2− x S and Cu 2− x Se display reversible phase transition to highly symmetric phases upon heating to a certain temperature. 166,189 For example, α-Cu 2 Se possesses a low symmetry monoclinic crystal structure at room temperature transitions to the cubic β-Cu 2 Se phase above 400 K (Fig.…”