Realizing high-ranged thermoelectric performance in PbSnS₂ crystals

Area of Science:

• Materials Science
• Solid State Physics
• Thermoelectrics

Background:

• Significant advancements in p-type tin sulfide (SnS) thermoelectric materials have been reported.
• The development of efficient n-type thermoelectric compounds, particularly sulfide-based ones, remains a challenge, hindering the fabrication of complete thermoelectric devices.

Purpose of the Study:

• To develop a high-performance n-type sulfide thermoelectric material based on SnS.
• To investigate the thermoelectric properties of lead-alloyed tin sulfide (PbSnS2) and understand the mechanisms behind its performance.

Main Methods:

• Alloying SnS with lead (Pb) to create n-type PbSnS2.
• Optimizing carrier concentration using chlorine (Cl) doping.
• Analyzing the Seebeck coefficient, power factor, and thermal conductivity over a temperature range of 300-773 K.
• Evaluating the thermoelectric performance in a single-leg device.

Main Results:

• Achieved a maximum figure of merit (ZT) of approximately 1.2 and an average ZT of ~0.75 between 300-773 K.
• Enhanced power factor through optimized carrier concentration and band structure engineering.
• Observed intrinsically ultralow lattice thermal conductivity due to complex crystal structure and anharmonicity.
• Demonstrated a maximum power generation efficiency of ~2.7% in a single-leg device.

Conclusions:

• Developed a high-performance n-type PbSnS2 thermoelectric material with promising properties.
• The enhanced performance is attributed to a synergistic effect of improved power factor and suppressed lattice thermal conductivity.
• PbSnS2 is a potential candidate to complement existing p-type SnS materials for practical thermoelectric applications.