Valence Bands in Lead Telluride

Allgaier, R. S.

doi:10.1063/1.1777039

Cited by 131 publications

(54 citation statements)

References 12 publications

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“…This region along the R line has been described and modeled as a separate, heavy band, even though recent work suggests it may be associated with the band at L. [8][9][10] However, twoband analysis, e.g., when both bands are considered separately, is consistent with most experimental observations and is useful for rational thermoelectric material design. 3,7,11,12 Based on historical evidence [13][14][15] and calculations, 9,10,16,17 the band extremum at R is believed to lie about 0.1-0.15 eV below that of the band at L at room temperature (see Figure 1(d)). Still, the exact band energies and their temperature dependence continue to be disputed.…”

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confidence: 99%

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Temperature dependent band gap in PbX (X = S, Se, Te)

Gibbs¹,

Kim²,

Wang³

et al. 2013

Applied Physics Letters

158

124

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PbTe is an important thermoelectric material for power generation applications due its high conversion efficiency and reliability. Its extraordinary thermoelectric performance is attributed to band convergence of the light L and heavy Σ bands. However, the temperature at which these bands converge is disputed. In this letter, we provide direct experimental evidence combined with ab initio calculations that confirm an increasing optical gap up to 673 K and predict a band convergence temperature of 700 K, much higher than previous measurements showing saturation and band convergence at 450 K.

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confidence: 99%

“…8,[13][14][15][18][19][20][21][22][23] Nevertheless, interpretation of the results depends upon transport models. Optical absorption edge spectroscopy in semiconductors is a more direct route to obtain information about electronic states near the band edge and specifically information concerning the value of the band gap E g .…”

mentioning

confidence: 99%

Temperature dependent band gap in PbX (X = S, Se, Te)

Gibbs¹,

Kim²,

Wang³

et al. 2013

Applied Physics Letters

158

124

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“…This can be explained by the increasing effective mass of carriers because of the temperature dependent mass of the light bands as well as the transition of holes from the light to the heavy band that has lower mobility. 19,[31][32][33][34][35][36][37][38] Increasing Hall density results in lower electrical resistivity in PbTe:Na/Ag 2 Te nanocomposites, as shown in Fig. 4.…”

Section: Broader Contextmentioning

confidence: 99%

“…The electronic transport, optical spectroscopy and other properties of p-PbTe can be well described by this two-valence-band mode. [31][32][33][34][35][36][37][38] Rather than the Seebeck coefficient being proportional to absolute temperature (e.g. n-type PbTe:La/Ag 2 Te in Fig.…”

Section: Broader Contextmentioning

confidence: 99%

Combination of large nanostructures and complex band structure for high performance thermoelectric lead telluride

Pei

Heinz

LaLonde

et al. 2011

Energy Environ. Sci.

165

112

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The complexity of the valence band structure in p-type PbTe has been shown to enable a significant enhancement of the average thermoelectric figure of merit (zT) when heavily doped with Na. It has also been shown that when PbTe is nanostructured with large nanometer sized Ag 2 Te precipitates there is an enhancement of zT due to phonon scattering at the interfaces. The enhancement in zT resulting from these two mechanisms is of similar magnitude but, in principle, decoupled from one another. This work experimentally demonstrates a successful combination of the complexity in the valence band structure with the addition of nanostructuring to create a high performance thermoelectric material. These effects lead to a high zT over a wide temperature range with peak zT > 1.5 at T > 650 K in Na-doped PbTe/Ag 2 Te. This high average zT produces 30% higher efficiency (300-750 K) than pure Na-doped PbTe because of the nanostructures, while the complex valence band structure leads to twice the efficiency as the related n-type La-doped PbTe/Ag 2 Te without such band structure complexity. Thermoelectric (TE) applications have attracted increasing interest in the last decade as a means to combat the ever growing rate of energy consumption throughout the world. The two main applications for thermoelectric materials are power generation, which utilizes the Seebeck effect, and solid state cooling, which has its roots in the Peltier effect. In recent years, thermoelectric power generation has been a prime interest to the automotive industry 1 as a sustainable and emission free route to vehicular waste heat recovery. The effectiveness of this process is restricted by the overall efficiency of the thermoelectric materials.On a materials level, the efficiency of the thermal to electrical energy conversion is determined by the thermoelectric figure of, where S, s, k E and k L are the Seebeck coefficient, electrical conductivity, and the electronic and lattice components of the thermal conductivity. Since S, s and k E have an intimate relationship with the carrier density, 1,2 the grand challenge in designing thermoelectric materials is the decoupling of electronic and thermal properties. Many methods to achieve a large power factor (S 2 s) or to reduce the thermal conductivity were proven to be successful, but combination of these two effects is difficult. As a result, the current best commercially available thermoelectric materials have a peak zT near unity.A number of mechanisms have been proposed to explain high zT in p-type PbTe. The Tl-doping in PbTe:Tl produces resonant electronic states that enhances the Seebeck coefficient, but reduces hole mobility 3 and has zT $ 1.4 at 500 C. Na-doped PbTe:Na, 4 without resonant states, 5,6 has similarly high zT that Materials Science, California Institute of Technology, Pasadena, CA, 91125, USA. E-mail: jsnyder@caltech.edu Broader contextThermoelectric generators, which directly convert heat into electricity are being considered for industrial or automotive waste heat recovery. However, th...

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“…PbTe [28][29][30] and SnTe [31][32][33][34] both have a higher-energy L and a lower-energy Σ valence band. In pristine materials with optimized carrier concentrations, the lower-energy offset between these two bands in PbTe (0.17 eV 29,30,35 at 300 K) compared with that in SnTe (0.3-0.4 eV 32,34 at 300 K) leads to a much higher-power factor (30 μW cm − 1 K − 2 36 ) for PbTe than that for SnTe (20 μW cm − 1 K − 2 37 ). For GeTe, the available literature shows a power factor of ∼ 40 μW cm − 1 K − 2 , [38][39][40][41] which is the highest among the three compounds.…”

Section: Introductionmentioning

confidence: 99%

Electronic origin of the high thermoelectric performance of GeTe among the p-type group IV monotellurides

et al. 2017

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PbTe and SnTe in their p-type forms have long been considered high-performance thermoelectrics, and both of them largely rely on two valence bands (the first band at L point and the second one along the Σ line) participating in the transport properties. This work focuses on the thermoelectric transport properties inherent to p-type GeTe, a member of the group IV monotellurides that is relatively less studied. Approximately 50 GeTe samples have been synthesized with different carrier concentrations spanning from 1 to 20 × 10 20 cm − 3 , enabling an insightful understanding of the electronic transport and a full carrier concentration optimization for the thermoelectric performance. When all of these three monotellurides (PbTe, SnTe and GeTe) are fully optimized in their p-type forms, GeTe shows the highest thermoelectric figure of merit (zT up to 1.8). This is due to its superior electronic performance, originating from the highly degenerated Σ band at the band edge in the low-temperature rhombohedral phase and the smallest effective masses for both the L and Σ bands in the high-temperature cubic phase. The high thermoelectric performance of GeTe that is induced by its unique electronic structure not only provides a reference substance for understanding existing research on GeTe but also opens new possibilities for the further improvement of the thermoelectric performance of this material.

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Valence Bands in Lead Telluride

Cited by 131 publications

References 12 publications

Temperature dependent band gap in PbX (X = S, Se, Te)

Temperature dependent band gap in PbX (X = S, Se, Te)

Combination of large nanostructures and complex band structure for high performance thermoelectric lead telluride

Electronic origin of the high thermoelectric performance of GeTe among the p-type group IV monotellurides

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