Lattice Strain Leads to High Thermoelectric Performance in Polycrystalline SnSe

Area of Science:

• Materials Science
• Solid State Physics
• Thermoelectrics

Background:

• Polycrystalline tin selenide (SnSe) is desirable for thermoelectric applications due to its processability.
• Achieving high thermoelectric performance in polycrystalline SnSe comparable to single crystals remains a challenge.

Purpose of the Study:

• To reduce lattice thermal conductivity in polycrystalline SnSe by engineering lattice strain.
• To enhance the thermoelectric performance of SnSe through band convergence and resonance level engineering.

Main Methods:

• Harnessing lattice strain via dislocations and stacking faults to reduce phonon relaxation time.
• Incorporating Gallium (Ga) to induce band convergence and resonance levels.
• Utilizing solution processing and non-toxic element doping for material fabrication.

Main Results:

• Achieved ultralow lattice thermal conductivity by engineering static lattice strain.
• Observed a sharp increase in Seebeck coefficient and power factor due to Ga incorporation.
• Reported a record high thermoelectric figure of merit (ZT) of ~2.2 for solution-processed SnSe polycrystals.
• Attained a high average ZT of 0.72 and thermoelectric conversion efficiency of 12.4%.

Conclusions:

• Engineering lattice strain is an effective strategy for reducing lattice thermal conductivity in SnSe.
• Band convergence and resonance levels enhance thermoelectric properties, leading to high performance.
• Solution-processed, doped SnSe polycrystals demonstrate significant potential for intermediate-temperature power generation.