n-Type Bi₂Te_3–xSe_x Nanoplates with Enhanced Thermoelectric Efficiency Driven by Wide-Frequency Phonon Scatterings and Synergistic Carrier Scatterings

Abstract

Driven by the prospective applications of thermoelectric materials, massive efforts have been dedicated to enhancing the conversion efficiency. The latter is governed by the figure of merit (ZT), which is proportional to the power factor (S(2)σ) and inversely proportional to the thermal conductivity (κ). Here, we demonstrate the synthesis of high-quality ternary Bi2Te3-xSex nanoplates using a microwave-assisted surfactant-free solvothermal method. The obtained n-type Bi2Te2.7Se0.3 nanostructures exhibit a high ZT of 1.23 at 480 K measured from the corresponding sintered pellets, in which a remarkably low κ and a shift of peak S(2)σ to high temperature are observed. By detailed electron microscopy investigations, coupled with theoretical analysis on phonon transports, we propose that the achieved κ reduction is attributed to the strong wide-frequency phonon scatterings. The shifting of peak S(2)σ to high temperature is due to the weakened temperature dependent transport properties governed by the synergistic carrier scatterings and the suppressed bipolar effects by enlarging the band gap.

Enhanced Thermoelectric Properties of Cu3SbSe4 Compounds via Gallium Doping

“…In addition, the relationship of µ H ∞ T −3/2 can be found at high temperature, which indicates that the dominant scattering mechanism of Cu 3 Sb 1−x Ga x Se 4 (0 ≤ x ≤ 0.015) compounds is phonon scattering. As the Ga content increases, the relationship of µ H ∞ T −3/2 of these compounds becomes weak, indicating that the dominant mechanism is mixed scattering for the Cu 3 Sb 1−x Ga x Se 4 compounds at high temperature [8] …”

“…Band engineering including electric band structure and valley degeneracy has been regarded as an efficient approach to improve the power factor (PF = α 2 σ), thereby enhancing the ZT. Doping or nanostructuring are also effective ways of enhancing the ZT by introducing extra phonon scattering centers [6][7][8][9][10].…”

Compositionally tunable ternary Bi2(Se1−xTex)3 and (Bi1−ySby)2Te3 thin films via low pressure chemical vapour deposition

“…These results provide strong evidence for a very well-distributed solid solution. 38,39 An additional peak at ca. 120 cm À1 is detected for Bi 2 (Se 0.3 Te 0.7 ) 3 and Bi 2 Te 3 ( Fig.…”

Effect of Oxygen Partial Pressure on the Phase Stability of Copper–Iron Delafossites at Elevated Temperatures

“…Whereas commonly used material classes such as chalcogenides [19,20,21,22,23,24,25,26,27,28,29], skudderudites [30,31,32], and polymers [33,34,35,36,37] exhibit good thermoelectric performance at low- and mid-temperature ranges, oxides show their advantages at elevated temperatures above 700 °C. Above all, oxide materials follow the prevailing trend to substitute costly and less abundant thermoelectrics in favor of inexpensive materials.…”