Development of Nanostructured Bi₂Te₃ with High Thermoelectric Performance by Scalable Synthesis and Microstructure Manipulations

Abstract

Nanostructuring of thermoelectric (TE) materials leads to improved energy conversion performance; however, it requires a perfect fit between the nanoprecipitates’ chemistry and crystal structure and those of the matrix. We synthesize bulk Bi2Te3 from molecular precursors and characterize their structure and chemistry using electron microscopy and analyze their TE transport properties in the range of 300–500 K. We find that synthesis from Bi2O3 + Na2TeO3 precursors results in n-type Bi2Te3 containing a high number density (N v ∼ 2.45 × 1023 m–3) of Te-nanoprecipitates decorating the Bi2Te3 grain boundaries (GBs), which yield enhanced TE performance with a power factor (PF) of ∼19 μW cm–1 K–2 at 300 K. First-principles calculations validate the role of Te/Bi2Te3 interfaces in increasing the charge carrier concentration, density of states, and electrical conductivity. These optimized TE coefficients yield a promising TE figure of merit (zT) peak value of 1.30 at 450 K and an average zT of 1.14 from 300 to 500 K. This is one of the cutting-edge zT values recorded for n-type Bi2Te3 produced by chemical routes. We believe that this chemical synthesis strategy will be beneficial for future development of scalable n-type Bi2Te3 based devices.

Comprehensive study of nanostructured Bi2Te3 thermoelectric materials – insights from synchrotron radiation XRD, XAFS, and XRF techniques

“…While solution methods have the advantage of allowing for the growth and control of various crystalline material architectures, they are only capable of producing a few grammes and cannot produce a high yield. 11 Using solution synthesis techniques, the ZT for n-type Bi 2 Te 3 could not be appreciably raised to values higher than 1. 29,30 Particular procedures require a lot of time to prepare the necessary materials which associated costly facilities.…”

“…5–7 As well, it is a strategy that holds promise for resolving the contradiction between the rising energy demand and the depletion of fossil fuels 2,8–10 by converting energy more sustainably utilising a noise-free, low-maintenance technique. 11 Thermoelectric modules have frequently been used for thermal management. 12 As a result, it is predicted that the global market for thermoelectric modules would grow to be worth US$ 1.3 billion by 2031 from its 2021 value of US$ 0.6 billion with growth rate 8.3%.…”

Thermoelectric Properties of Single-Phase n-Type Bi14Te13S8

“…Bi 2 Te 3 -based compounds are pioneer thermoelectric materials for room-temperature applications, and many attempts have been made to improve their efficiency over a wide temperature range. Several key strategies that stand out include optimization of the charge carrier concentration; , widening the band gap − to suppress the bipolar effect; enhancing the thermopower and thermal conductivity by alloying Bi 2 Te 3 with Sb − and Se; , nanostructuring to reduce the thermal conductivity; , and utilizing the convergence of electronic bands in alloys to further increase the zT . Significant progress on all fronts has led to record zT values for Bi 2 Te 3 -based compounds.…”

Flexible Thermoelectric Films Based on Bi2Te3 Nanowires and Boron Nitride Nanotube Networks with Carbon Doping

“…To improve the efficiency of energy use, researchers are focusing on efficient industrial waste heat recovery and conversion as well as the absorption and reuse of unused solar radiation from solar cells. The key to efficient, non-polluting, and low-cost thermoelectric (TE) conversion lies in the preparation of high-quality TE materials. − Conventional inorganic TE materials (consisting of covalent and ionic bonds) have various disadvantages, such as brittleness, inherent stiffness, and poor chemical stability. As a result, they are difficult to use in applications requiring complex and inhomogeneous heat source surfaces and can lead to poor contact or reduced TE conversion efficiency. − Currently, the TE capability of a material is assessed using the common index of TE properties, ZT, which is expressed as S 2 σ T /(κ e + κ l ) (where S is the Seebeck coefficient, σ is the electrical conductivity, κ e and κ l denote the electronic and lattice thermal conductivities of the TE material, respectively, and T is the absolute temperature). − To achieve high-efficiency TE conversion, TE materials with a high power factor (PF, S 2 σ) and low thermal conductivity (κ = κ e + κ l ) are required.…”

“…As a result, they are difficult to use in applications requiring complex and inhomogeneous heat source surfaces and can lead to poor contact or reduced TE conversion efficiency. 4−7 Currently, the TE capability of a material is assessed using the common index of TE properties, ZT, which is expressed as S 2 σT/(κ e + κ l ) (where S is the Seebeck coefficient, σ is the electrical conductivity, κ e and κ l denote the electronic and lattice thermal conductivities of the TE material, respectively, and T is the absolute temperature). 8−10 To achieve highefficiency TE conversion, TE materials with a high power factor (PF, S 2 σ) and low thermal conductivity (κ = κ e + κ l ) are required.…”