Realizing high-efficiency power generation in low-cost PbS-based thermoelectric materials

The application of thermoelectric technology is hindered by low efficiencies and high costs, demonstrating a strong demand for high-performance thermoelectric materials composed of low-cost and earth-abundant elements. PbS-based materials have attracted much attention for thermoelectric power generation due to their low-cost and earth-abundant features. However, the high lattice thermal conductivities and low electron mobilities of these materials limit their thermoelectric performance. Here, we show that we can largely reduce the lattice thermal conductivity of an n-type PbS-based material to 0.4 W m^-1 K^-1 through introducing zigzag nanoprecipitates with a uniform width of around 1 nm. The electron mobility was also successfully improved by reducing the effective mass through Se alloying. Finally, an extraordinary figure of merit of 1.7 at 900 K was realized in an n-type Pb_0.93Sb_0.05S_0.5Se_0.5 sample. A thermoelectric power generation module was fabricated with this n-type PbS material and our home-made high-performance p-type PbTe. It demonstrated a high conversion efficiency of 8.0% at a temperature difference of 565 K. Furthermore, a segmented module consisting of n-/p-Bi₂Te₃ and n-PbS/p-PbTe was fabricated, which exhibited a high conversion efficiency of 11.2% at a temperature difference of 585 K. This efficiency is the same as those of reported PbTe-based modules, and it was realized at a much lower cost. As a result, low-cost high-performance n-type PbS-based materials as a promising PbTe alternative will promote the extensive commercial application of thermoelectric power generation.