Realizing N-type SnTe Thermoelectrics with Competitive Performance through Suppressing Sn Vacancies

Area of Science:

• Materials Science
• Solid State Physics
• Nanotechnology

Background:

• Tin Telluride (SnTe) is a promising thermoelectric material, but achieving n-type conductivity is difficult due to inherent tin vacancies.
• Developing efficient n-type SnTe is crucial for realizing cost-effective thermoelectric devices based on both n- and p-type legs.

Purpose of the Study:

• To synthesize high-performance n-type SnTe thermoelectric materials.
• To suppress intrinsic tin vacancies and introduce electron doping.
• To investigate the effects of alloying and doping on thermoelectric properties.

Main Methods:

• Synthesized n-type SnTe via lead (Pb) alloying to suppress tin (Sn) vacancies.
• Introduced electron doping using iodine (I) to shift electrical transport from p-type to n-type.
• Utilized transmission electron microscopy to confirm vacancy population.

Main Results:

• Pb alloying effectively populated Sn vacancies, reducing their concentration.
• Iodine doping successfully shifted the material to n-type conductivity.
• Enhanced electrical conductivity through sharpened conduction bands (Pb alloying) and reduced lattice thermal conductivity via phonon scattering (Pb alloying and I doping).
• Achieved a peak figure of merit (ZTmax) of ~0.8 at 573 K and an average ZTave of ~0.51 from 300-823 K for n-type Sn_0.6Pb_0.4Te_0.98I_0.02.

Conclusions:

• Successfully developed high-performance n-type SnTe thermoelectric materials.
• The strategy of suppressing Sn vacancies and subsequent electron doping is effective.
• The achieved performance matches excellent p-type SnTe, making n-type SnTe a viable candidate for thermoelectric generation.