Origin of unusual thermoelectric transport behaviors in carbon nanotube filled polymer composites after solvent/acid treatments

Hsu, Jui-Hung; Choi, Woongchul; Yang, Gang; Yu, Choongho

doi:10.1016/j.orgel.2017.03.007

Cited by 65 publications

(29 citation statements)

References 52 publications

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“…The σ of as-deposited PEGL (604.4 S cm −1 ) is almost 200 times higher than that of the as-deposited PE films (2.90 S cm −1 ), because the glycerol additives effectively screened the Van der Waals and Coulomb interactions between PSS and PEDOT, removing excess PSS on PEDOT grains and constructing a large conducting pathway. [40,[45][46][47] Our optimized σ values were well matched with those of literatures. [21,48] On the other hand, the S of as-deposited PE was found to be almost the same as that of PEGL.…”

Section: Resultssupporting

confidence: 78%

“…Generally, σ and S have an inverse relationship as a function of carrier concentration that is precisely affected by oxidation level of PEDOT. [45][46][47] In other words, the decreased σ (and slightly increased S) indicated that the PEDOTs lost their carrier concentration during air-exposure. This was correlated with the previous XPS/UPS analyses that the chemical configurations of the PEDOT grain surfaces changed to water-adsorbed/oxidized state due to air-exposure, resulting in the loss of carrier concentration.…”

Section: Resultsmentioning

confidence: 99%

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In‐Situ Photoelectron Spectroscopy Study on the Air Degradation of PEDOT:PSS in Terms of Electrical and Thermoelectric Properties

Yun

Jung

Sung

et al. 2020

Adv Elect Materials

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In recent decades, a conducting polymer film: poly(3,4-ethylenedioxythiophene) polymerized with poly(4-styrenesulfonate) (PEDOT:PSS) has been employed as an essential component of flexible electronics used in practical products, owing to obvious advantages of its electrical and mechanical properties. Generally, the PEDOT:PSS shows an high electrical conductivity (>1000 S cm −1), deep work function (>5.0 eV), and good compatibility with other materials such as organic dopants, carbon nanomaterials, and inorganic nanowires, which has opened limitless possibilities for electronic application such as electrodes, charge transport layers, and thermoelectric active materials. [1-8] Some organic dopants include polar solvent additives such as dimethylsulfoxide (DMSO) and glycerol that contribute to a decrease in the Coulomb interactions between PEDOT and PSS chains and changed molecular arrangement of the PEDOT and PSS chains. [9] In addition, some non-ionic polymer surfactants have also been utilized to increase electrical conductivity of the PEDOT:PSS films by forming interconnected PEDOT networks in the PEDOT:PSS films. [10] Despite excellent electrical and mechanical properties, practical application of poly(3,4-ethylenedioxythiophene) polymerized with poly(4-styrenesulfonate) (PEDOT:PSS) face the challenge of ensuring air stability in electronic industry. Here, degradation mechanism of PEDOT:PSS-based films in air is clearly demonstrated through X-ray/ultraviolet photoelectron spectroscopy (XPS/ UPS) and its depth-profiling technique. As the duration of air-exposure increases, the PEDOT:PSS-based films alter molecular structures with the formation of SO x bond in PEDOT and CN x bond growth, changing ratios of insulating part (PSS − , PSSH, oxidized PEDOT) to conducting part and deteriorating their electrical conductivities. These transition behaviors are similar in all PEDOT:PSS-based films regardless of additives such as dopant or multi-walled carbon nanotube. Additionally, methanol treatment to various PEDOT:PSS-based films for inducing conformational change between PEDOT and PSS molecules, partly restore the electrical properties of the denatured PEDOT:PSS films. Finally, thermoelectric properties of the PEDOT:PSS-based films are characterized by investigating the effects of air-aging and methanol treatment on electrical conductivities, Seebeck coefficients, and power factors. To sum up, this study provides a useful guideline for establishing a strategy to ensure air stability of PEDOT:PSS-based films by clarifying the degradation mechanism and property recovery methods.

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Section: Resultssupporting

confidence: 78%

Section: Resultsmentioning

confidence: 99%

In‐Situ Photoelectron Spectroscopy Study on the Air Degradation of PEDOT:PSS in Terms of Electrical and Thermoelectric Properties

Yun

Jung

Sung

et al. 2020

Adv Elect Materials

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“…Hsu et al [140] prepared PEDOT:PSS/CNT thermoelectric materials with an unchanged or increased Seebeck coefficient, when the electrical conductivity increased with the increase of the CNT concentration or by post-treating the materials in dimethyl sulfoxide (DMSO) or formic acid (FA). Note that this is contrary to the correlation of electrical conductivity with the Seebeck coefficient.…”

Section: Carbon-based Organic Thermoelectric Materialsmentioning

confidence: 99%

Recent Advances in Organic Thermoelectric Materials: Principle Mechanisms and Emerging Carbon-Based Green Energy Materials

2019

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Thermoelectric devices have recently attracted considerable interest owing to their unique ability of converting heat to electrical energy in an environmentally efficient manner. These devices are promising as alternative power generators for harvesting electrical energy compared to conventional batteries. Inorganic crystalline semiconductors have dominated the thermoelectric material fields; however, their application has been restricted by their intrinsic high toxicity, fragility, and high cost. In contrast, organic thermoelectric materials with low cost, low thermal conductivity, easy processing, and good flexibility are more suitable for fabricating thermoelectric devices. In this review, we briefly introduce the parameters affecting the thermoelectric performance and summarize the most recently developed carbon-material-based organic thermoelectric composites along with their preparation technologies, thermoelectric performance, and future applications. In addition, the p- and n-type carbon nanotube conversion and existing challenges are discussed. This review can help researchers in elucidating the recent studies on carbon-based organic thermoelectric materials, thus inspiring them to develop more efficient thermoelectric devices.

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“…Simultaneous enhancement of electrical conductivity and Seebeck coefficient has been observed in the CNT‒polymer composites, which is unusual and does not follow the Wiedemann‒Franz law [120]. Typically, an increase in electrical conductivity accompanies a decrease in the Seebeck coefficient, and vice versa.…”

Section: Cnt‒polymer Compositesmentioning

confidence: 99%

Carbon Nanotube-Based Organic Thermoelectric Materials for Energy Harvesting

Wang

Liu

2018

Polymers

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Carbon nanotubes (CNTs) have attracted much attention in developing high-performance, low-cost, flexible thermoelectric (TE) materials because of their great electrical and mechanical properties. Theory predicts that one-dimensional semiconductors have natural advantages in TE fields. During the past few decades, remarkable progress has been achieved in both theory and experiments. What is more important is that CNTs have shown desirable features for either n-type or p-type TE properties through specific strategies. Up to now, CNT‒polymer hybrids have held the record for TE performance in organic materials, which means they can potentially be used in high-performance TE applications and flexible electronic devices. In this review, we intend to focus on the intrinsic TE properties of both n-type and p-type CNTs and effective TE enhanced strategies. Furthermore, the current trends for developing CNT-based and CNT‒polymer-based high TE performance organic materials are discussed, followed by an overview of the relevant electronic structure‒TE property relationship. Finally, models for evaluating the TE properties are provided and a few representative samples of CNT‒polymer composites with high TE performance are highlighted.

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Origin of unusual thermoelectric transport behaviors in carbon nanotube filled polymer composites after solvent/acid treatments

Cited by 65 publications

References 52 publications

In‐Situ Photoelectron Spectroscopy Study on the Air Degradation of PEDOT:PSS in Terms of Electrical and Thermoelectric Properties

In‐Situ Photoelectron Spectroscopy Study on the Air Degradation of PEDOT:PSS in Terms of Electrical and Thermoelectric Properties

Recent Advances in Organic Thermoelectric Materials: Principle Mechanisms and Emerging Carbon-Based Green Energy Materials

Carbon Nanotube-Based Organic Thermoelectric Materials for Energy Harvesting

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