High Thermoelectric Performance of p-Type PbTe Enabled by the Synergy of Resonance Scattering and Lattice Softening

Abstract

In this work, we show the simultaneous enhancement of electrical transport and reduction of phonon propagation in p-type PbTe codoped with Tl and Na. The effective use of advanced electronic structure engineering improves the thermoelectric power factor S 2 σ over the temperature range from 300 to 825 K. A rise in the Seebeck coefficient S was obtained due to the enhanced effective mass m*, coming from the Tl resonance state in PbTe. Due to the presence of additional carriers brought by Na codoping, electrical conductivity became significantly improved. Furthermore, Tl and Na impurities induced crystal lattice softening, remarkably reducing lattice thermal conductivity, which was confirmed by a measured low speed of sound v m and high internal strain Cε XRD . Eventually, the combination of both the attuned electronic structure and the lattice softening effects led to a very high ZT value of up to ∼2.1 for the Pb 1−x−y Tl x Na y Te samples. The estimated energy conversion efficiency shows the extraordinary value of 15.4% (T c = 300 K, T h = 825 K), due to the significantly improved average thermoelectric figure of merit ZT ave = 1.05. This work demonstrates that the combination of impurity resonance scattering and crystal lattice softening can be a breakthrough concept for advancing thermoelectrics.

Feasibility of high performance in p‐type Ge1−xBixTe materials for thermoelectric modules

“…The carrier concentration of pristine GeTe is extremely high, up to ∼10 21 cm −3 , which is much higher than the optimal value for maximum TE performance. 59 Pb doping in Ge 1−x Pb x Te only slightly decreases the value of the carrier concentration due to the isovalent nature of Pb in place of Ge. A relatively small decrease in carrier concentration observed for Pbdoped GeTe is due to the reduced deviation from the stoichiometric composition, as reported in our recent work.…”

Phase Analysis and Thermoelectric Properties of Cu-Rich Tetrahedrite Prepared by Solvothermal Synthesis

“…Details of the calculations can be found in refs. [12,13]. Cu-rich tetrahedrites have the effective mass m * around 0.9 m e , which is in between Cu 12 Sb 4 S 12 (phase I) ~0.68 m e [57] and Cu 12 Sb 4 S 13 (phase II) ~1.3 m e [56].…”

“…The concentration-dependent Seebeck coefficient at 298 K was calculated using the Kane band model, considering acoustic phonons as the main scattering mechanism (scattering parameter r = 0). Within this model, the Seebeck coefficient S could be defined using the following expression [3,13]:…”

“…As the Seebeck coefficient, electrical conductivity, and electronic thermal conductivity are interrelated through the carrier concentration and particularities of the band structure, the development of the highly efficient TE materials requires specific properties (narrow bandgap, multivalley band structure, high mobility, high solubility of dopants, intrinsically low κ lat ) [9][10][11]. Such an unusual combination of properties in one compound was found in the heavily-doped semiconductors, e.g., PbTe [12][13][14], Bi 2 Te 3 [15,16], GeTe [17,18], CoSb 3 [19,20], which are excellent thermoelectric materials. The limiting factors, which restrict their widespread utilization, are the costs of production, environmental friendliness, and efficiency of energy conversion.…”

Transport properties of binary phosphide AgP2 denoting high Hall mobility and low lattice thermal conductivity

“…Thus, because it is difficult to recover energy from low-temperature waste heat in a steam turbine, thermoelectric conversion is attracting attention as a technology to recover energy from low-temperature waste heat. The most widely used thermoelectric materials are Te compounds, such as Bi 2 Te 3 [1,2] and PbTe [3,4]. However, because of the low earth abundance of Te -approximately the same as that of Pt [5]-alternative materials are needed to replace Te compounds for mass production.…”