Synergistic Texturing and Bi/Sb‐Te Antisite Doping Secure High Thermoelectric Performance in Bi_0.5Sb_1.5Te₃‐Based Thin Films

Abstract

dominated by the dimensionless figure of merit, ZT = S 2 σT/κ, where S, σ, T, and κ are the Seebeck coefficient, electrical conductivity, absolute temperature, and total thermal conductivity, respectively. [2] Among them, S 2 σ, defined as the power factor, is used to evaluate the overall electrical performance, and κ is the accumulation of lattice thermal conductivity (κ l ) and electrical thermal conductivity (κ e ) as an overall estimation of the thermal performance. [3] To realize a high ZT, both a high S 2 σ and a low κ are required. However, these parameters are strongly interrelated, and the carrier concentration (n p for p-type semiconductors with holes as the main carriers and n e for n-type semiconductors with electrons as the main carriers) needs to be optimized in accordance with high carrier mobility (μ) and low κ l . [4] The n p and n e can be optimized by tuning the valence electron counts through cation and anion doping, which can lead to optimized S 2 σ. [5] The energy filtering effect can boost μ without significant deterioration of other properties, increasing S 2 σ. [6] Band engineering strategies, such as band convergence and resonant state engineering, can effectively increase S. [7,8] In terms of suppressing κ l , various scattering centers have been introduced into thermoelectric materials to strengthening phonon scattering at full wavelength scale (ranging from microscale to atomic scale) and miniaturize κ l . [9] Most typically, dense point defects introduced by doping/alloying, [10] corresponding dense dislocations, [11] and strain fields, [12] can effectively scatter short-wavelength phonons, and dramatically reduce κ l . Dense grain boundaries and interfaces introduced by nanostructuring and nanoprecipitates can strengthen mid-to long-wavelength phonon scattering. [13] Hierarchical architecture engineering, [14] the combination of these phonon scattering strategies, can dramatically reduce κ l to the amorphous limit and further contribute to high ZT values. [2] Bi 2 Te 3 -based thermoelectric materials, including p-type Bi 0.5 Sb 1.5 Te 3 -based and n-type Bi 2 Te 3 -based ones, have been extensively studied due to their high performance (room-temperature ZT > 1). [15] Both Bi 2 Te 3 and Bi 0.5 Sb 1.5 Te 3 have strong anisotropy, leading to high thermoelectric performance along the in-plane directions. [16] In recent years, Bi 2 Te 3 -based thin films are attracting increasing attention due to their considerable wearability and Bi 2 Te 3 -based thin films are attracting increasing attention due to their considerable wearability and flexibility feature. However, the relatively low performance compared to their bulk counterparts limits their development and wider application. In this work, synergistic texturing and Bi/Sb-Te antisite doping are used to achieve a high room-temperature ZT of ≈1.5 in p-type Bi 0.5 Sb 1.5 Te 3 thin films by a magnetron sputtering method. Structural characterization confirms that carefully tuning the deposition temperature can strengthen the texture of as-pre...

Tuning the Saturated Vapor Pressure of Solvothermal Synthesis to Boost the Thermoelectric Performance of Pristine Bi2Te3 Polycrystals by Anisotropy Strengthening

“…The m* possesses the same trend of as-measured n e , indicating that there is no obvious energy filtering or blocking effect in the system since all bulk materials are composed of pure Bi 2 Te 3 without any other phase . For E def , increasing the saturated vapor pressure, E def is continuously decreased, indicating the strengthened texturing effect . As a reference, the bulk material sintered from the commercial powder shows the highest E def , indicating the lowest anisotropy.…”

“…59 For E def , increasing the saturated vapor pressure, E def is continuously decreased, indicating the strengthened texturing effect. 60 As a reference, the bulk material sintered from the commercial powder shows the highest E def , indicating It can be seen that the bulk materials sintered from our solvothermally synthesized microplates show higher κ, which should be derived from their high κ e . Figure 6b shows the calculated temperaturedependent Lorentz number L by an SPB model, and Figure 6c shows the determined temperature-dependent κ e by κ e = LσT, 62 from which the κ e possess the same trends as σ.…”

3D Printing of Bi2Te3-Based Thermoelectric Materials with High Performance and Shape Controllability

“…The electron transport properties at room temperature were characterized by employing Hall measurements (Table S3). The main reason for the lower carrier concentration in the annealed sample compared to the as-printed sample is the reduction of the antisite defects which can effectively suppress the carrier concentration. , The carrier mobilities in both directions are enhanced due to less amount of grain boundaries as well as the weaker carrier–carrier scattering after the annealing process. Seebeck coefficients as a function of temperature are given in Figure b.…”

Advances in flexible inorganic thermoelectrics

“…So far, bismuth telluride (Bi 2 Te 3 )-based thermoelectric materials remain one of the best options for near-roomtemperature thermoelectric applications, owing to their narrow bandgaps of ~0.1 eV, 9,55 high intrinsic S, high σ, and low κ. 15,[56][57][58][59][60][61] Bi 2 Te 3 has a trigonal crystal structure with a space group of R3m. 9,55 It forms a hexagonal layered structure where each layer consists of 5 atoms arranged in a vertical direction.…”