Copper ion liquid-like thermoelectrics

Single crystal tin selenide (SnSe) has attracted much attention for its excellent thermoelectric performance. However, polycrystalline SnSe exhibits unsatisfactory figure‐of‐merit due to the inferior electrical properties, especially for n‐type SnSe. In this work, a high concentration of Br doping (6–12 atm%) on the Se site effectively increases the Hall carrier concentration from 1.6 × 1017 cm−3 (p‐type) in undoped SnSe to 1.3 × 1019 cm−3 (n‐type) in Br‐doped SnSe0.88Br0.12, leading to an increased electrical conductivity close to that of a single crystal. Combined with the decreased lattice thermal conductivity due to the enhanced phonon scattering by composition fluctuation and dislocations, a peak ZT of ≈1.3 at 773 K, together with the enhanced average ZT is obtained in SnSe0.9Br0.1 along the hot pressing direction.

Section: Introductionmentioning

confidence: 99%

Heavy Doping by Bromine to Improve the Thermoelectric Properties of n‐type Polycrystalline SnSe

Wang

Chen

et al. 2018

“…One effective strategy for ZT improvement is to minimize the lattice thermal conductivity by scattering phonons off crystal defects, e.g., grain boundaries,9, 10, 11, 12, 13, 14 dislocations,15, 16, 17, 18 point defects,19, 20, 21, 22, 23, 24, 25 nanoprecipitates,26, 27, 28, 29, 30 etc. However, thermoelectric power generation demands not only high ZT but also high PF over a wide range of temperature, which directly determines output power density ω, another crucial parameter for power generation 31, 32, 33.…”

Section: Introductionmentioning

confidence: 99%

“…Such a substantial enhancement is mainly ascribed to the improved carrier mobility (>20 cm 2 V −1 s −1 at 300 K). As a result, this p‐type NbFeSb system possesses more competitive PF than other high‐performance thermoelectric materials (e.g., lead telluride, bismuth telluride, etc 10, 12, 29, 35, 56, 57, 58, 59 1 .…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Ultrahigh Power Factor in Thermoelectric System Nb_0.95M_0.05FeSb (M = Hf, Zr, and Ti)

Ren

Zhu

et al. 2018

Conversion efficiency and output power are crucial parameters for thermoelectric power generation that highly rely on figure of merit ZT and power factor (PF), respectively. Therefore, the synergistic optimization of electrical and thermal properties is imperative instead of optimizing just ZT by thermal conductivity reduction or just PF by electron transport enhancement. Here, it is demonstrated that Nb0.95Hf0.05FeSb has not only ultrahigh PF over ≈100 µW cm−1 K−2 at room temperature but also the highest ZT in a material system Nb0.95M0.05FeSb (M = Hf, Zr, Ti). It is found that Hf dopant is capable to simultaneously supply carriers for mobility optimization and introduce atomic disorder for reducing lattice thermal conductivity. As a result, Nb0.95Hf0.05FeSb distinguishes itself from other outstanding NbFeSb‐based materials in both the PF and ZT. Additionally, a large output power density of ≈21.6 W cm−2 is achieved based on a single‐leg device under a temperature difference of ≈560 K, showing the realistic prospect of the ultrahigh PF for power generation.

“…Current efforts to improve zT are focused on the optimization of power factor α 2 σ through controlled doping or electron band engineering,7, 8, 9, 10, 11 suppression in κ L by alloying or nanostructuring,1, 2, 5, 6 and development of new materials with intrinsically low κ L 12, 13, 14, 15. Heat‐carrying phonons cover a broad spectrum of frequency, and the κ L is a sum of contributions from phonons of different frequencies.…”

mentioning

confidence: 99%

Enhancing the Figure of Merit of Heavy‐Band Thermoelectric Materials Through Hierarchical Phonon Scattering

Liu

et al. 2016

148

Hierarchical scattering is suggested as an effective strategy to enhance the figure of merit zT of heavy‐band thermoelectric materials. Heavy‐band FeNbSb half‐Heusler system with intrinsically low carrier mean free path is demonstrated as a paradigm. An enhanced zT of 1.34 is obtained at 1150 K for the Fe1.05Nb0.75Ti0.25Sb compound with intentionally designed hierarchical scattering centers.