Thermoelectrics from abundant chemical elements: high-performance nanostructured PbSe-PbS

Area of Science:

• Materials Science
• Solid-state Physics
• Thermoelectrics

Background:

• The lead selenide-lead sulfide (PbSe-PbS) system offers potential for thermoelectric applications due to abundant constituent elements.
• Understanding the influence of alloying and nanostructuring on thermoelectric properties is crucial for material optimization.

Purpose of the Study:

• To investigate the thermoelectric properties of the PbSe-PbS system, focusing on the impact of alloying and nanostructure formation.
• To evaluate the potential of this system for efficient thermoelectric energy conversion.

Main Methods:

• Synthesis and characterization of PbSe-PbS alloys with varying compositions.
• Doping strategies using PbCl(2), excess Pb, and Bi to achieve n-type behavior.
• Transmission electron microscopy (TEM) to analyze nanostructure formation.
• Measurement of thermoelectric transport properties (carrier mobility, power factor) and thermal conductivity.

Main Results:

• PbSe-PbS alloys exhibit n-type behavior with transport properties similar to pristine n-type PbSe up to 16% PbS.
• Unexpected nanoprecipitates (~2-5 nm) were observed, increasing with PbS concentration, contrary to previous solid solution assumptions.
• Nanostructuring significantly reduced lattice thermal conductivity compared to theoretical predictions.
• Optical phonon excitations were found to contribute to heat transport across all temperatures.

Conclusions:

• The PbSe-PbS system demonstrates promising thermoelectric performance, achieving figures of merit up to ~1.2-1.3 at 900 K.
• The observed nanostructuring plays a critical role in enhancing thermoelectric efficiency by reducing thermal conductivity.
• These findings suggest the feasibility of large-scale thermoelectric applications using inexpensive and abundant materials.