Anisotropy of thermoelectric power of stretch-oriented new polyacetylene

Pukacki, W.; Płocharski, Janusz; Roth, S.

doi:10.1016/0379-6779(94)90213-5

Cited by 31 publications

(25 citation statements)

References 5 publications

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“…6b). [14,88±90] The thermopower was first found to be anisotropic in some samples of stretched PAc by Pukacki et al, [90] as illustrated by samples d,e in Figure 6b, which provides evidence for heterogeneity in the samples.…”

Section: Thermoelectric Powermentioning

confidence: 93%

Systematic Conductivity Behavior in Conducting Polymers: Effects of Heterogeneous Disorder

Kaiser¹

2001

Adv. Mater.

279

200

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The conduction process in conducting polymers has some unusual features. Even for highly conducting samples, the electronic transport properties show a mixture of metallic and non‐metallic character, which is most easily explained in terms of the heterogeneous morphology of the polymers. The Figure shows the characteristic temperature dependence of conductivity as doping level is increased. A key feature of the conductivity of the organic conducting polymers is its surprisingly large magnitude for materials with low carrier density and considerable disorder. For polyacetylene the inferred conductivity of the highly conducting crystalline regions can be greater than that of copper. However, the temperature dependence of the conductivity shows non‐metallic sign over a wide range of temperatures in virtually all conducting polymers—a change to metallic sign occurs only at higher temperatures and only in some polymers. This behavior is compared and contrasted with that of carbon nanotubes (which can also be regarded as conducting polymers) and of amorphous conventional metals. The measured conductivities of organic polymers and single‐wall carbon nanotube networks are analyzed in terms of a heterogeneous model that gives a good account of the data. The granularity of the superconductivity recently discovered in polythiophene films is also consistent with this heterogeneous model.

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Section: Thermoelectric Powermentioning

confidence: 93%

Systematic Conductivity Behavior in Conducting Polymers: Effects of Heterogeneous Disorder

Kaiser¹

2001

Adv. Mater.

279

200

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“…Currently, dipping polymers into dopant solutions or exposing polymers to a dopant vapor/atmosphere are the two most prevalent methods to perform p‐ and n‐type chemical doping. For p‐type doping, common dopants include I 2 , FeCl 3 , and the ferric salt of triflimide (Fetf) . For n‐type doping, common dopants include tetrakis(dimethylamino)ethylene (TDAE), hydrazine, and polyethylenimine (PEI) .…”

Section: Strategies To Optimize the Properties Of Conductive Polymersmentioning

confidence: 99%

“…a) Mechanism of redox‐based doping through chemical reactions. b) Molecular structures of common n‐type dopants tetrakis(dimethylamino)ethylene (TDAE), hydrazine, and polyethylenimine (PEI); p‐type dopants including I 2 , FeCl 3 , and the ferric salt of triflimide (Fetf) . c) Electrical conductivity (σ), Seebeck coefficient ( S ), and power factor ( S 2 σ) of TDAE‐doped PEDOT:Tos, where a promising zT peak of 0.25 is achieved.…”

Section: Strategies To Optimize the Properties Of Conductive Polymersmentioning

confidence: 99%

Flexible Thermoelectric Materials and Generators: Challenges and Innovations

et al. 2019

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The urgent need for ecofriendly, stable, long‐lifetime power sources is driving the booming market for miniaturized and integrated electronics, including wearable and medical implantable devices. Flexible thermoelectric materials and devices are receiving increasing attention, due to their capability to convert heat into electricity directly by conformably attaching them onto heat sources. Polymer‐based flexible thermoelectric materials are particularly fascinating because of their intrinsic flexibility, affordability, and low toxicity. There are other promising alternatives including inorganic‐based flexible thermoelectrics that have high energy‐conversion efficiency, large power output, and stability at relatively high temperature. Herein, the state‐of‐the‐art in the development of flexible thermoelectric materials and devices is summarized, including exploring the fundamentals behind the performance of flexible thermoelectric materials and devices by relating materials chemistry and physics to properties. By taking insights from carrier and phonon transport, the limitations of high‐performance flexible thermoelectric materials and the underlying mechanisms associated with each optimization strategy are highlighted. Finally, the remaining challenges in flexible thermoelectric materials are discussed in conclusion, and suggestions and a framework to guide future development are provided, which may pave the way for a bright future for flexible thermoelectric devices in the energy market.

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“…Overall, as observed previously for F 4 TCNQ-doped P3HT, the anisotropy in thermopower is always smaller than that of the charge conductivity. [46,47] Kaiser proposed a heterogeneous model of metallic fibrils separated by electrical barriers to explain this observation. For instance, the rubbed C 12 -PBTTT sequentially doped with 5 × 10 −3 m FeCl 3 /nitromethane has σ // = 2.2 × 10 5 S cm −1 and S // = 9.4 ± 0.5 µV K −1 .…”

Section: Anisotropy Of Thermopower and Power Factormentioning

confidence: 99%

“…The present situation bears similarity with the case of doped oriented PA fibers that show S // /S ⊥ > 1. [46,47] Kaiser proposed a heterogeneous model of metallic fibrils separated by electrical barriers to explain this observation. [46] In doped PA, semiconducting barriers alternate with metallic domains and modulate the thermopower and its anisotropy.…”

Section: Anisotropy Of Thermopower and Power Factormentioning

confidence: 99%

Bringing Conducting Polymers to High Order: Toward Conductivities beyond 10⁵ S cm⁻¹ and Thermoelectric Power Factors of 2 mW m⁻¹ K⁻²

Vijayakumar

Zhong

Untilova

et al. 2019

Advanced Energy Materials

168

181

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Here, an effective design strategy of polymer thermoelectric materials based on structural control in doped polymer semiconductors is presented. The strategy is illustrated for two archetypical polythiophenes, e.g., poly(2,5‐bis(3‐dodecyl‐2‐thienyl)thieno[3,2‐b]thiophene) (C12‐PBTTT) and regioregular poly(3‐hexylthiophene) (P3HT). FeCl3 doping of aligned films results in charge conductivities up to 2 × 105 S cm−1 and metallic‐like thermopowers similar to iodine‐doped polyacetylene. The films are almost optically transparent and show strongly polarized near‐infrared polaronic bands (dichroic ratio >10). The comparative study of structure–property correlations in P3HT and C12‐PBTTT identifies three conditions to obtain conductivities beyond 105 S cm−1: i) achieve high in‐plane orientation of conjugated polymers with high persistence length; ii) ensure uniform chain oxidation of the polymer backbones by regular intercalation of dopant molecules in the polymer structure without disrupting alignment of π‐stacked layers; and iii) maintain a percolating nanomorphology along the chain direction. The highly anisotropic conducting polymer films are ideal model systems to investigate the correlations between thermopower S and charge conductivity σ. A scaling law S ∝ σ−1/4 prevails along the chain direction, but a different S ∝ −ln(σ) relation is observed perpendicular to the chains, suggesting different charge transport mechanisms. The simultaneous increase of charge conductivity and thermopower along the chain direction results in a substantial improvement of thermoelectric power factors up to 2 mW m−1 K−2 in C12‐PBTTT.

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Anisotropy of thermoelectric power of stretch-oriented new polyacetylene

Cited by 31 publications

References 5 publications

Systematic Conductivity Behavior in Conducting Polymers: Effects of Heterogeneous Disorder

Systematic Conductivity Behavior in Conducting Polymers: Effects of Heterogeneous Disorder

Flexible Thermoelectric Materials and Generators: Challenges and Innovations

Bringing Conducting Polymers to High Order: Toward Conductivities beyond 10⁵ S cm⁻¹ and Thermoelectric Power Factors of 2 mW m⁻¹ K⁻²

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Anisotropy of thermoelectric power of stretch-oriented new polyacetylene

Cited by 31 publications

References 5 publications

Systematic Conductivity Behavior in Conducting Polymers: Effects of Heterogeneous Disorder

Systematic Conductivity Behavior in Conducting Polymers: Effects of Heterogeneous Disorder

Flexible Thermoelectric Materials and Generators: Challenges and Innovations

Bringing Conducting Polymers to High Order: Toward Conductivities beyond 105 S cm−1 and Thermoelectric Power Factors of 2 mW m−1 K−2

Contact Info

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Bringing Conducting Polymers to High Order: Toward Conductivities beyond 10⁵ S cm⁻¹ and Thermoelectric Power Factors of 2 mW m⁻¹ K⁻²