n-Type Nanostructured Thermoelectric Materials Prepared from Chemically Synthesized Ultrathin Bi₂Te₃ Nanoplates

Abstract

We herein report on the large-scale synthesis of ultrathin Bi(2)Te(3) nanoplates and subsequent spark plasma sintering to fabricate n-type nanostructured bulk thermoelectric materials. Bi(2)Te(3) nanoplates were synthesized by the reaction between bismuth thiolate and tri-n-octylphosphine telluride in oleylamine. The thickness of the nanoplates was ~1 nm, which corresponds to a single layer in Bi(2)Te(3) crystals. Bi(2)Te(3) nanostructured bulk materials were prepared by sintering of surfactant-removed Bi(2)Te(3) nanoplates using spark plasma sintering. We found that the grain size and density were strongly dependent on the sintering temperature, and we investigated the effect of the sintering temperature on the thermoelectric properties of the Bi(2)Te(3) nanostructured bulk materials. The electrical conductivities increased with an increase in the sintering temperature, owing to the decreased interface density arising from the grain growth and densification. The Seebeck coefficients roughly decreased with an increase in the sintering temperature. Interestingly, the electron concentrations and mobilities strongly depended on the sintering temperature, suggesting the potential barrier scattering at interfaces and the doping effect of defects and organic residues. The thermal conductivities also increased with an increase in the sintering temperature because of grain growth and densification. The maximum thermoelectric figure-of-merit, ZT, is 0.62 at 400 K, which is one of the highest among the reported values of n-type nanostructured materials based on chemically synthesized nanoparticles. This increase in ZT shows the possibility of the preparation of highly efficient thermoelectric materials by chemical synthesis.

Thermal annealing effect on structural and thermoelectric properties of hexagonal Bi2Te3 nanoplate thin films by drop-casting technique

“…To improve the quality of nanoplates in solvothermal synthesis, various challenges must be overcome by modifying the experimental conditions. [24][25][26][27] To fabricate the ideal thermoelectric thin film, the nanoplates should be obtained in thin films. One of the most convenient methods of fabricating thin nanoplate films is the drop-casting technique using nanoplate inks because of its easy scalability, high deposition rate, and no requirement for vacuum conditions.…”

Single-crystalline Bi2Te3 nanosheets with uniform morphology via a simple, efficient, and high-yield microwave-assisted synthesis

“…Bi 2 Te 3 hexagonal nanosheets are a typical representative of low-dimensional materials. Hyeon et al reported on ultrathin Bi 2 Te 3 nanosheets with ZT value of 0.62 at 400 K, which is one of the highest values among the reported ones based on chemically synthesized nanoparticles [17,18]. Current efforts toward fabricating Bi 2 Te 3 nanosheets are focused on hydrothermal reaction, solution-phase synthesis, and metal organic chemical vapor deposition (MOCVD).…”

Thermoelectric Performance of Micro/Nano-Structured Bismuth-Antimony-Telluride Bulk from Low Cost Mechanical Alloying

“…The peak ZT of the bulk sample made from powders through the H-reduction is about 0.8 near the temperature of 80˚C. It is among the desired value of the high performance of thermoelectric material families of Bi 2 Te 3 alloys, for applications around 75˚C to 100˚C [18,19].…”