Simultaneously achieving high ZT and mechanical hardness in highly alloyed GeTe with symmetric nanodomains

Wang, De‐Zhuang; Liu, Wei‐Di; Li, Meng; Yin, Liang‐Cao; Gao, Han; Sun, Qiang; Wu, Hao; Wang, Yifeng; Shi, Xiao‐Lei; Yang, Xiaoning; Li, Qingfeng

doi:10.1016/j.cej.2022.136131

Cited by 39 publications

(15 citation statements)

References 52 publications

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“…The lowest κ l is reported to be ∼0.2 W m –1 K –1 in Ge 0.86 Mn 0.1 Sb 0.04 Te . Characterizations and modeling studies suggest that such a low κ l originates from the dramatically strengthened phonon scatterings by the coexistence of grain boundaries, point defects, twin grain boundaries, and dislocations, as well as the low phonon group velocity originating from the weakened chemical bonds. − …”

Section: Dampening the Phonon Propagationmentioning

confidence: 97%

Chemistry in Advancing Thermoelectric GeTe Materials

Hong

Chen

2022

Acc. Chem. Res.

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Metrics & MoreArticle Recommendations CONSPECTUS:The ever-growing energy crisis and the deteriorated environment caused by carbon energy consumption motivate the exploitation of alternative green and sustainable energy supplies. Because of the unique advantages of zero-emission, no moving parts, accurate temperature control, a long steady-state operation period, and the ability to operate in extreme situations, thermoelectrics, enabling the direct conversion between heat and electricity, is a promising and sustainable option for power generation and refrigeration. However, with increasing application potentials, thermoelectrics is now facing a major challenge: developing high-performance, Pb-free, and lowtoxic thermoelectric materials and devices.As one group of promising candidates, GeTe derivatives have the potential to replace the widely used thermoelectric materials containing highly toxic elements.In this Account, we summarize our recent progress in developing highperformance GeTe-based thermoelectric materials via exploring innovative strategies to enhance electron transports and dampen phonon propagations. First, we fundamentally illustrate the underlying chemistry and physical reason for an intrinsically high carrier concentration in GeTe, which enormously restrains the thermoelectric performance of GeTe. From our theoretical calculations, the formation energy of Ge vacancy is the lowest among the defects in GeTe, energetically favoring Ge vacancies in the lattice and leading to intrinsically high carrier concentrations. Accordingly, aliovalent doping/alloying is proposed to increase the formation energy of Ge vacancies and decrease the carrier concentration to the optimal level. We then outline the newly developed method to refine the band structures of GeTe with tuned electronic transport. On the basis of the molecular orbital theory, the energy offset between two valence band edges at the L and Σ points in GeTe should be ascribed to the slightly different Ge_4s orbital characters at these two points, which guides the screening of dopants for band convergence. Besides, the Rashba spin splitting is explored to increase the band degeneracy of GeTe. Afterward, we analyze the dampened phonon propagation in GeTe to minimize its lattice thermal conductivity. Alloying with the heavy Sb atoms can shift the optical phonon modes toward low frequency and reinforce the interaction of optical and acoustic phonon modes so that the inherent phonon scattering is enhanced. In addition, planar vacancies and superlattice precipitates can significantly strengthen phonon scattering to result in ultralow lattice thermal conductivity. After that, we overview the finite elemental analysis simulations to optimize the device geometry for maximizing the device performance and introduce the as-developed prototype GeTe-based thermoelectric device. In the end, we point out future directions in the development of GeTe for device applications. The strategies summarized in this Account can serve as references for developing wide materi...

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Section: Dampening the Phonon Propagationmentioning

confidence: 97%

Chemistry in Advancing Thermoelectric GeTe Materials

Hong

Chen

2022

Acc. Chem. Res.

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“…The distinctive feature of energy level switching between the L and S valence bands enables an extra degree of freedom for the possibility of band manipulation, which is essential for improving the electronic properties via high band degeneracy [187,190]. The band structure of c-GeTe is like that of PbTe and SnTe, making c-GeTe tutored a potential material for device application [197]. As such, a high zT > 2 [189,191,192] has been found for c-GeTe, which is superior to several of the mid-temperature p-type thermoelectric materials.…”

Section: Germanium Telluridesmentioning

confidence: 99%

Isovalent substitution in metal chalcogenide materials for improving thermoelectric power generation – A critical review

Musah

Ilyas

Venkatesh

et al. 2022

Nano Research Energy

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The adverse effect of fossil fuels on the environment is driving research to explore alternative energy sources. Research studies have demonstrated that renewables can offer a promising strategy to curb the problem, among which thermoelectric technology stands tall. However, the challenge with thermoelectric materials comes from the conflicting property of the Seebeck coefficient and the electrical conductivity resulting in a low power factor and hence a lower figure of merit. Researchers have reported various techniques to enhance the figure of merit, particularly in metal chalcogenide thermoelectric materials.Here we present a review on isovalent substitution as a tool to decouple the interdependency of the electrical conductivity and Seebeck coefficient to facilitate simultaneous enhancement in these two parameters. This is proven true in both cationic and anionic side substitutions in metal chalcogenide thermoelectric materials. Numerous publications relating to isovalent substitution in metal chalcogenide thermoelectric are reviewed. This will serve as a direction for current and future research to enhance thermoelectric performance and device application. This review substantiates the role of isovalent substitution in enhancing metal chalcogenide thermoelectric properties compared with conventional systems.

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“…1,2 In any industrial process, for automobiles and electrical devices, nearly 64% of the energy is wasted as heat and the majority of such waste heat sources have a temperature of <100 °C. 3 To harness hightemperature waste heat (>100 °C), a wide variety of thermoelectric materials including doped GeTe 4,5 and PbTe 6,7 with high values of average figures of merit are reported. So far, conducting polymer-based composites and bismuth telluride (Bi 2 Te 3 ) are the most successful materials for harvesting low-temperature waste heat (<100 °C).…”

Section: ■ Introductionmentioning

confidence: 99%

Improved Power Factor in Highly Textured n-Type Ag₂Se Flexible Films

Sarkar

Samanta

Das

et al. 2023

ACS Appl. Electron. Mater.

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Flexible thin films of mixed ion−electron conductor Ag 2 Se are an attractive candidate for wearable thermoelectric applications near room temperature. In this work, deposition of Se/Ag 2 Se 1−δ bi-layers by simple thermal evaporation followed by annealing enhances the Se content in the Ag 2 Se 1−δ films. The Se enrichment of the Ag 2 Se 1−δ films resulted in the improvement of the power factor through improved texturing and an enhanced Seebeck coefficient due to reduced carrier concentration. Films with Se/Ag ratio of ∼0.5 showed the highest power factor of ∼22 μW cm −1 K −2 at 320 K, i.e., 85% higher than that of films with Se/Ag ratio of 0.33. These high-performance films exhibited a very mild reversible change in the Seebeck coefficient and resistance on convex bending. A thermoelectric generator with 10 uni-legs of optimized films showed an outstanding power density of 2.6 W m −2 at a temperature difference of 10 K.

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Simultaneously achieving high ZT and mechanical hardness in highly alloyed GeTe with symmetric nanodomains

Cited by 39 publications

References 52 publications

Chemistry in Advancing Thermoelectric GeTe Materials

Chemistry in Advancing Thermoelectric GeTe Materials

Isovalent substitution in metal chalcogenide materials for improving thermoelectric power generation – A critical review

Improved Power Factor in Highly Textured n-Type Ag₂Se Flexible Films

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Simultaneously achieving high ZT and mechanical hardness in highly alloyed GeTe with symmetric nanodomains

Cited by 39 publications

References 52 publications

Chemistry in Advancing Thermoelectric GeTe Materials

Chemistry in Advancing Thermoelectric GeTe Materials

Isovalent substitution in metal chalcogenide materials for improving thermoelectric power generation – A critical review

Improved Power Factor in Highly Textured n-Type Ag2Se Flexible Films

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Product

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About

Improved Power Factor in Highly Textured n-Type Ag₂Se Flexible Films