Wet-Chemical Synthesis and Consolidation of Stoichiometric Bismuth Telluride Nanoparticles for Improving the Thermoelectric Figure-of-Merit

Abstract

Bismuth telluride nanoparticles (NPs) have been synthesized using a low-temperature wet-chemical approach from bismuth(III) oleate and tri-n-octylphosphine telluride. The size and shape of the NPs can be controlled by adjusting the temperature, reaction time, and nature of the surfactants and solvents. Aromatic hydrocarbons (toluene, xylenes) and ethers (phenyl- and benzyl-ether) favor the formation of stoichiometric Bi2Te3 NPs of platelike morphology, whereas the presence of oleylamine and 1-dodecanethiol yields Bi-rich Bi2Te3 spherical NPs. XRD, IR, SEM, TEM, and SAED techniques have been used to characterize the obtained products. We show that the surfactants can be efficiently removed from the surface of the NPs using a two-step process employing nitrosonium tetrafluoroborate and hydrazine hydrate. The surfactant-free NPs were further consolidated into high density pellets using cold-pressing and field-assisted sintering techniques. The sintered surfactant-free Bi2Te3 showed electrical and thermal properties comparable to Bi2Te3 materials processed through conventional solid state techniques, and greatly improved over other nanostructured Bi2Te3 materials synthesized by wet-chemical approaches.

Towards Infrared Electronic Eyes: Flexible Colloidal Quantum Dot Photovoltaic Detectors Enhanced by Resonant Cavity

“…Before drop‐casting the HgTe CQDs solution, a thin layer of Bi 2 Se 3 nanocrystals was spin‐coated on the ITO as electron transport layer. The Bi 2 Se 3 nanocrystals were prepared following a protocol adapted from the previous report . Bismuth acetate (0.2 mmol) was dissolved in oleic acid (5 mL) at 70 °C for 1 h, forming a clear solution.…”

“…The Bi 2 Se 3 nanocrystals were prepared following a protocol adapted from the previous report. [32] Bismuth acetate (0.2 mmol) was dissolved in oleic acid (5 mL) at 70 °C for 1 h, forming a clear solution. Then, stoichiometric (2:3) amount of TOPSe (0.3 mmol) was injected.…”

Wet-chemical synthesis of different bismuth telluride nanoparticles using metal organic precursors – single source vs. dual source approach

“…Asobtained particles reached ZT values of 0.38 at room temperature. [5] Moreover, bismuth nitrate and TOPTe were thermolyzed in octadecene and oleic acid by Ruan et al, resulting in the formation of hexagonal und rod-shaped particles, [6] while Borca-Tasciuc et al obtained hexagonal Bi 2 Te 3 plates from the reaction of BiCl 3 and TOPTe in thioglycolic acid in a microwave assisted synthesis. [7] The resulting material, which was sub-atomically doped with sulphur, showed a remarkably high ZT value (1.1).…”

Green synthesis and formation mechanism of nanostructured Bi2Te3 using ascorbic acid in aqueous solution

“…2(e). Syntheses of disk-like Bi 2 Te 3 NPs with diameters ranging from approximately 10 nm-2.0 lm by various synthesis methods were widely reported [14,18,[21][22][23][24][25][26][27][28]. A rhombohedral Bi 2 Te 3 crystal has a layered anisotropic lattice structure with the Te and Bi atom layers arranged in the order of -Te (1) -Bi-Te (2) -Bi-Te (1) -along the c-axis direction [10].…”