Characteristics of lattice thermal conductivity and carrier mobility of undoped PbSe-PbS solid solutions

Solid solution has been considered as an effective approach to advanced thermoelectrics. However, the benefit from the decrease in lattice thermal conductivity induced by the impurity scattering will be compensated by the reduction in carrier mobility, therefore suppressing the maximum figure of merit (zT). We demonstrate the characteristics of the fundamental properties, including the lattice thermal conductivity and carrier mobility, of undoped PbSe_(1−x)S_x solid solutions (0 < x < 1) at room temperature, which provide an efficient way to evaluate the maximum zT of the materials with optimum doping. The lattice thermal conductivity is found to decrease significantly after adding a small amount of PbSe into PbS matrix up to the composition of PbSe_(0.7)S_(0.3) when the carrier mobility remains virtually unchanged, indicating the beneficial effect of impurity scattering to improve the thermoelectric performance