Excessively Doped PbTe with Ge-Induced Nanostructures Enables High-Efficiency Thermoelectric Modules

Jood, Priyanka; Ohta, Mitsuo; Yamamoto, Atsushi; Kanatzidis, Mercouri G.

doi:10.1016/j.joule.2018.04.025

Cited by 195 publications

(195 citation statements)

References 64 publications

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“…Therefore, the zT s are usually high in tellurides and selenides, but they are low in sulfides. This is the general phenomenon that has been observed in those well‐known TE materials such as Bi 2 X 3 ‐, SnX‐, and PbX‐based compounds (X = S, Se, and Te) . As shown in Figure , the zT values gradually improve as the anion element change from S to Se and then to Te.…”

supporting

confidence: 52%

Are Cu₂Te‐Based Compounds Excellent Thermoelectric Materials?

et al. 2019

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With the increasingly serious environmental pollution and intensified energy crisis, exploitation and utilization of new kinds of clean energy resources are imperative. Among them, thermoelectric (TE) conversion technology based on highperformance TE materials enables direct energy conversion between heat and electricity through the movement of internal phonons and charge carriers. [1][2][3][4] It has shown extensive and important prospects in power generation using industrial waste heat and electronic refrigeration. [5] The energy conversion efficiency of a TE material is mainly determined by its dimensionless figure of merit, defined as zT = σS 2 T/(κ L + κ e ), where σ, S, T, κ L , and κ e are the electrical conductivity, Seebeck coefficient, absolute temperature, lattice thermal conductivity, and electronic thermal conductivity, respectively. The general criteria for high zTs require high crystal symmetry for materials, many valleys (carrier pockets) near the Fermi level, heavy elements with small electronegativity differences between the constituent elements, or complex crystal structure, etc. [6][7][8][9][10] For the constituent elements in the same group such as S, Se, and Te, the heavy one (Te and Se) always has large atomic mass for low κ L and more covalent bonding character for large carrier mobility (µ H ) and thus outstanding electrical transports. [10] Therefore, the zTs are usually high in tellurides and selenides, but they are low in sulfides. This is the general phenomenon that has been observed in those well-known TE materials such as Bi 2 X 3 -, SnX-, and PbX-based compounds (X = S, Se, and Te). As shown in Figure 1, the zT values gradually improve as the anion element change from S to Se and then to Te. However, the case is different in Cu 2 X-based liquidlike TE materials that are among the hottest materials in recent TE study. They possess exceptionally low thermal conductivity and excellent zTs with the values of 1.7-1.9 for Cu 2 S, 1.5-2.3 for Cu 2 Se, and 0.4-1.1 for Cu 2 Te (see Figure 1). [48][49][50][51][52][53][54][55][56][57][58][59][60][61][62] It is quite abnormal and interesting that the zT in Cu 2 Te is lower than those in Cu 2 S and Cu 2 Se. As we known, tellurium is less electronegative, thus the chemical bonds between Cu and Te should be less ionic as compared with those in Cu 2 S and Cu 2 Se, which is beneficial for large µ H and electrical transports. Besides, the κ L in Cu 2 Te is expected lower than or similar to those in Cu 2 S and Cu 2 Se because tellurium is much heavier than sulfur and Most of the state-of-the-art thermoelectric (TE) materials exhibit high crystal symmetry, multiple valleys near the Fermi level, heavy constituent elements with small electronegativity differences, or complex crystal structure. Typically, such general features have been well observed in those well-known TE materials such as Bi 2 X 3 -, SnX-, and PbX-based compounds (X = S, Se, and Te). The performance is usually high in the materials with heavy constituent elements such as Te and Se, bu...

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confidence: 52%

Are Cu₂Te‐Based Compounds Excellent Thermoelectric Materials?

et al. 2019

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“…[3][4][5][6] As heat is supplied to give a temperature gradient across the constituent TE materials in the module, a potential gradient is spontaneously induced by the Seebeck effect to generate electric energy. [3][4][5][6] As heat is supplied to give a temperature gradient across the constituent TE materials in the module, a potential gradient is spontaneously induced by the Seebeck effect to generate electric energy.…”

Section: Introductionmentioning

confidence: 99%

Cu Intercalation and Br Doping to Thermoelectric SnSe₂ Lead to Ultrahigh Electron Mobility and Temperature‐Independent Power Factor

Zhou

Zhang

et al. 2019

Adv Funct Materials

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Due to its single conduction band nature, it is highly challenging to enhance the power factor of SnSe 2 by band convergence. Here, it is reported that simultaneous Cu intercalation and Br doping induce strong Cu-Br interaction to connect SnSe 2 layers, otherwise isolated, via "electrical bridges." Atom probe tomography analysis confirms a strong attraction between Cu intercalants and Br dopants in the SnSe 2 lattice. Density functional theory calculations reveal that this interaction delocalizes electrons confined around SnSe covalent bonds and enhances charge transfer across the SnSe 2 slabs. These effects dramatically increase electron mobility and concentration. Polycrystalline SnCu 0.005 Se 1.98 Br 0.02 shows even higher electron mobility than pristine SnSe 2 single crystal and the theoretical expectation. This results in significantly improved electrical conductivity without reducing effective mass and Seebeck coefficient, thereby leading to the highest power factor of ≈12 µW cm −1 K −2 to date for polycrystalline SnSe 2 and SnSe. It even surpasses the value for the state-of-the-art n-type SnSe 0.985 Br 0.015 single crystal at elevated temperatures. Surprisingly, the achieved power factor is nearly independent of temperature ranging from 300 to 773 K. The engineering thermoelectric figure of merit ZT eng for SnCu 0.005 Se 1.98 Br 0.02 is ≈0.25 between 773 and 300 K, the highest ZT eng ever reported for any form of SnSe 2 -based thermoelectric materials.

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“…Their solid‐state and compact nature makes thermoelectric generators (TEGs) produced from such high ZT materials a promising technology for capturing waste heat and boosting energy efficiency. Despite considerable ZT increases in the past two decades realized via nanostructuring and other techniques, a huge chasm still remains to make TEGs a cost‐competitive and commercially viable technology for a broad range of applications. The conventional TEG manufacturing process is expensive and inflexible, which is not adaptable for different applications.…”

Section: Introductionmentioning

confidence: 99%

Flexible Thermoelectric Devices of Ultrahigh Power Factor by Scalable Printing and Interface Engineering

Varghese

Dun

Kempf

et al. 2019

Adv Funct Materials

120

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Printing is a versatile method to transform semiconducting nanoparticle inks into functional and flexible devices. In particular, thermoelectric nanoparticles are attractive building blocks to fabricate flexible devices for energy harvesting and cooling applications. However, the performance of printed devices are plagued by poor interfacial connections between nanoparticles and resulting low carrier mobility. While many rigid bulk materials have shown a thermoelectric figure of merit ZT greater than unity, it is an exacting challenge to develop flexible materials with ZT near unity. Here, a scalable screen-printing method to fabricate high-performance and flexible thermoelectric devices is reported. A tellurium-based nanosolder approach is employed to bridge the interfaces between the BiSbTe particles during the postprinting sintering process. The printed BiSbTe flexible films demonstrate an ultrahigh room-temperature power factor of 3 mW m −1 K −2 and ZT about 1, significantly higher than the best reported values for flexible films. A fully printed thermoelectric generator produces a high power density of 18.8 mW cm −2 achievable with a small temperature gradient of 80 °C. This screen-printing method, which directly transforms thermoelectric nanoparticles into high-performance and flexible devices, presents a significant leap to make thermoelectrics a commercially viable technology for a broad range of energy harvesting and cooling applications.

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Excessively Doped PbTe with Ge-Induced Nanostructures Enables High-Efficiency Thermoelectric Modules

Cited by 195 publications

References 64 publications

Are Cu₂Te‐Based Compounds Excellent Thermoelectric Materials?

Are Cu₂Te‐Based Compounds Excellent Thermoelectric Materials?

Cu Intercalation and Br Doping to Thermoelectric SnSe₂ Lead to Ultrahigh Electron Mobility and Temperature‐Independent Power Factor

Flexible Thermoelectric Devices of Ultrahigh Power Factor by Scalable Printing and Interface Engineering

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Excessively Doped PbTe with Ge-Induced Nanostructures Enables High-Efficiency Thermoelectric Modules

Cited by 195 publications

References 64 publications

Are Cu2Te‐Based Compounds Excellent Thermoelectric Materials?

Are Cu2Te‐Based Compounds Excellent Thermoelectric Materials?

Cu Intercalation and Br Doping to Thermoelectric SnSe2 Lead to Ultrahigh Electron Mobility and Temperature‐Independent Power Factor

Flexible Thermoelectric Devices of Ultrahigh Power Factor by Scalable Printing and Interface Engineering

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Are Cu₂Te‐Based Compounds Excellent Thermoelectric Materials?

Are Cu₂Te‐Based Compounds Excellent Thermoelectric Materials?

Cu Intercalation and Br Doping to Thermoelectric SnSe₂ Lead to Ultrahigh Electron Mobility and Temperature‐Independent Power Factor