The synergic regulation of conductivity and Seebeck coefficient in pure polyaniline by chemically changing the ordered degree of molecular chains

Qin, Yao; Wang, Qun; Wang, Liming; Wang, Yan; Sun, Jing; Zeng, Huarong; Jin, Zhiyue; Huang, Xi; Chen, Lidong

doi:10.1039/c3ta14008c

Cited by 135 publications

(98 citation statements)

References 27 publications

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“…This more expanded conformation of PANi leads to the delocalization of carriers along the backbone chain and hence the carrier mobility increases. [ 35 ] Attenuated total refl ection (ATR) FTIR analysis gives further evidence for the strong binding of polymers in the multilayers ( Figure S5b, Supporting Information). The spectrum of the QL assembly is nearly the superposition of the spectra of individual PANi and PEDOT:PSS solutions, demonstrating the successful introduction of both polymers into the multilayers.…”

Section: Resultsmentioning

confidence: 91%

Outstanding Low Temperature Thermoelectric Power Factor from Completely Organic Thin Films Enabled by Multidimensional Conjugated Nanomaterials

Cho

Wallace

Tzeng

et al. 2016

Advanced Energy Materials

251

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between 2010 and 2040.[ 1 ] Sustainability is critical because current affordable energy, mainly from fossil fuels, is being rapidly depleted, while world demand increases. Even if the supply were unlimited, the use of fossil fuels is accompanied by environmental problems, such as pollution and the greenhouse effect. [ 2 ] Efforts to harness sustainable energy from solar, wind, nuclear, and other sources have shown promise, but cost and effi ciency remain signifi cant challenges to widespread adoption. Approximately 60% of all energy produced is wasted as heat, [ 3 ] which has driven the development of thermoelectric (TE) materials over the past two decades. [ 4 ] Heat is an abundant energy supply that can be harvested from a multitude of sources (engines, human body, etc.) with no moving parts. The TE performance is directly related to a dimensionless fi gureof-merit ( ZT = S 2 σ T κ −1 ), where S is the Seebeck coeffi cient, σ is the electrical conductivity, and κ is the thermal conductivity at a given temperature T . It is clear that a large σ and S , with a small κ , are desired to achieve high effi ciency ( ZT ≈ 1 corresponds to 4%-5% conversion effi ciency), [ 5 ] but there is a well-known confl ict among the three parameters that imposes limitations on traditional thermoelectric semiconductor development. [ 6 ] The best inorganic TE materials have achieved a ZT > 2, [ 7 ] but it should be noted that this value is measured at temperatures >600 K. The ZT of these materials at room temperature is <0.5, with a power factor (PF) <400 µW m −1 K −2 . These best commercially available materials are bismuth telluride-based alloys that are expensive and plagued by scarcity and toxicity concerns. Additionally, TE materials would need a ZT ≥ 3 to be effi cient enough to enter the power generation fi eld, making them commercially viable for more than niche applications. [ 8 ] Alternatively, low cost and lightweight materials that are printable (or paintable) could be useful even with relatively low conversion effi ciency.More recently, size effects in nanostructured systems such as nanowires, [ 9 ] quantum dots, [ 10 ] superlattices, [ 11 ] and a wide variety of composites with irregular nanosized inclusions have led to signifi cant improvements in thermoelectric efficiency over traditional bulk semiconductors. [ 12,13 ] For instance,In an effort to create a paintable/printable thermoelectric material, comprised exclusively of organic components, polyaniline (PANi), graphene, and double-walled nanotube (DWNT) are alternately deposited from aqueous solutions using the layer-by-layer assembly technique. Graphene and DWNT are stabilized with an intrinsically conductive polymer, poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS). An 80 quadlayer thin fi lm (≈1 µm thick), comprised of a PANi/graphene-PEDOT:PSS/PANi/DWNT-PEDOT:PSS repeating sequence, exhibits unprecedented electrical conductivity ( σ ≈ 1.9 × 10 5 S m −1 ) and Seebeck coeffi cient ( S ≈ 120 µV K −1 ) for a completely organic material. These t...

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Section: Resultsmentioning

confidence: 91%

Outstanding Low Temperature Thermoelectric Power Factor from Completely Organic Thin Films Enabled by Multidimensional Conjugated Nanomaterials

Cho

Wallace

Tzeng

et al. 2016

Advanced Energy Materials

251

242

View full text Add to dashboard Cite

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“…Conducting polymer TE materials possess the advantages of low κ, good flexibility and low cost in comparison with inorganic materials. [1][2][3][4] Among them, commercially available PEDOT:polystyrenesulfonate (PEDOT:PSS) has received the most attention due to its excellent water processability and high σ ( refs 5-11 ) and is also widely used as an electrode or conductive adhesive material in applications including solar cells, 12,13 organic light-emitting diodes (OLEDs), 14,15 supercapacitors, 16,17 sensors 18,19 and so on. The PSS polyanion enables the formation of aqueous PEDOT:PSS solutions, which benefits both film printing and the synthesis of hybrid materials.…”

Section: Introductionmentioning

confidence: 99%

Micron-thick highly conductive PEDOT films synthesized via self-inhibited polymerization: roles of anions

Shi

Qin

et al. 2017

NPG Asia Mater

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The inhibitor-dependent poly(3,4-ethylenedioxythiophene) (PEDOT) fabrication suffers major problems in the areas of controllability and film thickness. In this work, we found that anions play a key role in both the polymerization and the structure of PEDOT. As a precursor, anions greatly influence the reaction rate and oxidant solubility. In its role as a counter-ion, the anions also affect chain conductance and crystal growth. With these behaviors in mind, a self-inhibited polymerization approach using novel oxidants with appropriate anions was successfully developed to facilitate the fabrication of high quality in situ polymerized PEDOT films and solve the thickness limitation problem. Inhibitor-free heavy oxidative solutions with weakly basic anions enable the spin-coating of thick and homogeneous oxidant layers and also effectively inhibit both the crystallization of the oxidant and H + formation throughout the polymerization process. PEDOT: dodecylbenzenesulfonate (PEDOT:DBSA) exhibits the highest performance among all candidates due to its appropriate anion basicity and low steric effect. An extremely high doping level of 42.9% is achieved, and an electrical conductivity of~1100 S cm − 1 is successfully maintained for film thicknesses between 310 nm and 1.79 μm. In addition, the thermoelectric power factor (RT) for pristine films was improved to 77.2 μW mK − 2 from 69.6 μW mK − 2 by the dedoping treatment. This study provides a new approach for fabricating high performance PEDOT thick films using anion-based design. NPG Asia Materials (2017) 9, e405; doi:10.1038/am.2017.107; published online 14 July 2017 INTRODUCTION Thermoelectric (TE) materials realize direct conversion between heat and electricity, which can be used in refrigeration and power generation. The performance of TE materials is characterized by the ZT value (S 2 σT/κ) or power factor (S 2 σ), where S, σ, T and κ are the Seebeck coefficient, electrical conductivity, absolute temperature and thermal conductivity, respectively. Conducting polymer TE materials possess the advantages of low κ, good flexibility and low cost in comparison with inorganic materials. 1-4 Among them, commercially available PEDOT:polystyrenesulfonate (PEDOT:PSS) has received the most attention due to its excellent water processability and high σ ( refs 5-11 ) and is also widely used as an electrode or conductive adhesive material in applications including solar cells, 12,13 organic light-emitting diodes (OLEDs), 14,15 supercapacitors, 16,17 sensors 18,19 and so on. The PSS polyanion enables the formation of aqueous PEDOT:PSS solutions, which benefits both film printing and the synthesis of hybrid materials. However, such PSS-based processes also experience difficulties with performance optimization. For example, the insulating PSS lamellas remain in the polymer matrix, 20,21 resulting in an amorphous polymer 22 with limited σ and S. 5,9 Compared to PEDOT:PSS, PEDOT doped with smallsized anions (S-PEDOTs), such as tosylate (OTs) or triflate (OTf), have greater potential...

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“…The poor transport of electrons is caused by the coil conformation and random aggregation of P3HT polymer chains, which is largely due to the flexible hexyl side chains. [30][31][32][33] Organic small-molecule epitaxy is one effective way to increase the degree of ordering of polymer chains at the molecular level by using the appropriate small-molecule crystals as the epitaxial template. Usually, if the mismatch between the lattice spacing of the host (small-molecule crystals) and the guest (polymer backbones) is o10-15%, template-induced epitaxial growth is performed relatively easily.…”

Section: Introductionmentioning

confidence: 99%

Highly anisotropic P3HT films with enhanced thermoelectric performance via organic small molecule epitaxy

et al. 2016

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Conducting polymers are potential candidates for thermoelectric (TE) applications owing to their low thermal conductivity, non-toxicity and low cost. However, the coil conformation and random aggregation of polymer chains usually degrade electrical transport properties, thus deteriorating TE performance. In this work, we fabricated poly(3-hexylthiophene) (P3HT) films with highly oriented morphology using 1,3,5-trichlorobenzene (TCB), an organic small-molecule, as a template for polymer epitaxy under a temperature gradient crystallization process. The resulting P3HT molecules, which were confirmed to be highly anisotropic by a combination of scanning electron microscopy, atomic force microscopy, polarizing microscope, polarized Raman spectroscopy, and two-dimensional-grazing incidence X-ray diffraction (GIXRD) analysis, not only markedly reduced the conjugated defects along the polymer backbone, but also effectively increased the degree of electron delocalization. These combined phenomena produced an efficient, 1D path for carrier movement and therefore resulted in enhanced carrier mobility in the TCB-treated P3HT films. The maximum values of the electrical conductivity and Seebeck coefficient were 320 S cm À1 and 269 μV K À1 , respectively. Consequently, the maximum TE power factor and ZT value at 365 K reached 62.4 μW mK À2 and 0.1, respectively, in the parallel direction of the TCB-treated P3HT film. To the best of our knowledge, these are the highest values reported for pure P3HT TE materials. The method of using organic small-molecule epitaxy to generate highly anisotropic polymer films is expected to be valid for many conducting polymers.

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The synergic regulation of conductivity and Seebeck coefficient in pure polyaniline by chemically changing the ordered degree of molecular chains

Abstract: Pure polyaniline (PANI) films with different molecular chain packing states were successfully prepared by simply tuning the m-cresol content in the solvent.

Cited by 135 publications

References 27 publications

Outstanding Low Temperature Thermoelectric Power Factor from Completely Organic Thin Films Enabled by Multidimensional Conjugated Nanomaterials

Outstanding Low Temperature Thermoelectric Power Factor from Completely Organic Thin Films Enabled by Multidimensional Conjugated Nanomaterials

Micron-thick highly conductive PEDOT films synthesized via self-inhibited polymerization: roles of anions

Highly anisotropic P3HT films with enhanced thermoelectric performance via organic small molecule epitaxy

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