Low‐Dimensional Conduction Mechanisms in Highly Conductive and Transparent Conjugated Polymers

Ugur, Asli; Katmis, Ferhat; Li, Mingda; Wu, Lijun; Zhu, Yimei; Varanasi, Kripa K.; Gleason, Karen K.

doi:10.1002/adma.201502340

Cited by 106 publications

(134 citation statements)

References 41 publications

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“…Grazing incidence wide-angle x-ray scattering (GIWAXS) represents a powerful technique for the structural characterization of polymers [4,18,29,30]. An interpretation of the scattering pattern emerging from the GIWAXS measurements is that the the PEDOT films are polycrystals consisting of (mono)crystallites embedded in an amorphous matrix.…”

Section: Model and Methodsmentioning

confidence: 99%

“…Nowadays, poly (3,4-ethylenedioxythiopehene) or PEDOT has been the most studied conducting polymer due its high electronic (hole) conductivity (1000-4000 S/cm) [4][5][6], room-temperature stability [7], and remarkable thermoelectric properties with the highest figure of merit for organic materials [8][9][10][11]. Given the temperature dependence of conductivity σ (σ increases with the temperature T ) and the high degree of inherent disorder, it is generally accepted that the transport in doped conductive polymers is mediated by phonon-assisted hopping between the localized states [12][13][14][15][16][17][18]. These states are associated with singly (polaron) or doubly (bipolaron) positively charged defects (geometrical distortion of the chains) forming due to the strong electron-phonon coupling.…”

Section: Introductionmentioning

confidence: 99%

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Insulator to semimetallic transition in conducting polymers

et al. 2016

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We report a multiscale modeling of electronic structure of a conducting polymer poly(3,4-ethylenedioxythiopehene) (PEDOT) based on a realistic model of its morphology. We show that when the charge carrier concentration increases, the character of the density of states (DOS) gradually evolves from the insulating to the semimetallic, exhibiting a collapse of the gap between the bipolaron and valence bands with the drastic increase of the DOS between the bands. The origin of the observed behavior is attributed to the effect of randomly located counterions giving rise to the states in the gap. These results are discussed in light of recent experiments. The method developed in this work is general and can be applied to study the electronic structure of other conducting polymers.

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Section: Model and Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Insulator to semimetallic transition in conducting polymers

et al. 2016

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“…We investigated the chain length impact on mobility by considering systems with N = 3,6,9,12,15, and 18. (Note that the experimental value for PEDOT chain length is not known exactly and estimated to be N = 5-15 monomer units) [47,48]. A representative morphology obtained through this procedure is presented in Fig.…”

Section: A From Morphology To Resistive Networkmentioning

confidence: 99%

Understanding morphology-mobility dependence in PEDOT:Tos

Rolland

Franco-González

Volpi

et al. 2018

Phys. Rev. Materials

103

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The potential of conjugated polymers to compete with inorganic materials in the field of semiconductor is conditional on fine-tuning of the charge carriers mobility. The latter is closely related to the material morphology, and various studies have shown that the bottleneck for charge transport is the connectivity between well-ordered crystallites, with a high degree of π -π stacking, dispersed into a disordered matrix. However, at this time there is a lack of theoretical descriptions accounting for this link between morphology and mobility, hindering the development of systematic material designs. Here we propose a computational model to predict charge carriers mobility in conducting polymer PEDOT depending on the physicochemical properties of the system. We start by calculating the morphology using molecular dynamics simulations. Based on the calculated morphology we perform quantum mechanical calculation of the transfer integrals between states in polymer chains and calculate corresponding hopping rates using the Miller-Abrahams formalism. We then construct a transport resistive network, calculate the mobility using a mean-field approach, and analyze the calculated mobility in terms of transfer integrals distributions and percolation thresholds. Our results provide theoretical support for the recent study [Noriega et al., Nat. Mater. 12, 1038] explaining why the mobility in polymers rapidly increases as the chain length is increased and then saturates for sufficiently long chains. Our study also provides the answer to the long-standing question whether the enhancement of the crystallinity is the key to designing high-mobility polymers. We demonstrate, that it is the effective π -π stacking, not the long-range order that is essential for the material design for the enhanced electrical performance. This generic model can compare the mobility of a polymer thin film with different solvent contents, solvent additives, dopant species or polymer characteristics, providing a general framework to design new high mobility conjugated polymer materials.

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“…Figure compares the PEDOT film coated on flat Si wafer and PEDOT coating layer on GaAs nanowire I with thickness of 200 nm as thicker coating layer provides stronger signal. The peak at 6.4° corresponds to the edge‐on configuration (as shown in Figure ) with a d ‐spacing of 1.38 nm, while the peak at 26° corresponds to a face‐on configuration (as shown in Figure ) with a d ‐spacing of 0.34 nm . Other peaks are mainly generated by FeO x from the oCVD process.…”

Section: Resultsmentioning

confidence: 98%

Room Temperature Sensing Achieved by GaAs Nanowires and oCVD Polymer Coating

Wang

Ermez

Göktaş

et al. 2017

Macromol. Rapid Commun.

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Novel structures comprised of GaAs nanowire arrays conformally coated with conducting polymers (poly(3,4-ethylenedioxythiophene) (PEDOT) or poly(3,4-ethylenedioxythiophene-co-3-thiophene acetic acid) display both sensitivity and selectivity to a variety of volatile organic chemicals. A key feature is room temperature operation, so that neither a heater nor the power it would consume, is required. It is a distinct difference from traditional metal oxide sensors, which typically require elevated operational temperature. The GaAs nanowires are prepared directly via self-seeded metal-organic chemical deposition, and conducting polymers are deposited on GaAs nanowires using oxidative chemical vapor deposition (oCVD). The range of thickness for the oCVD layer is between 100 and 200 nm, which is controlled by changing the deposition time. X-ray diffraction analysis indicates an edge-on alignment of the crystalline structure of the PEDOT coating layer on GaAs nanowires. In addition, the positive correlation between the improvement of sensitivity and the increasing nanowire density is demonstrated. Furthermore, the effect of different oCVD coating materials is studied. The sensing mechanism is also discussed with studies considering both nanowire density and polymer types. Overall, the novel structure exhibits good sensitivity and selectivity in gas sensing, and provides a promising platform for future sensor design.

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Low‐Dimensional Conduction Mechanisms in Highly Conductive and Transparent Conjugated Polymers

Cited by 106 publications

References 41 publications

Insulator to semimetallic transition in conducting polymers

Insulator to semimetallic transition in conducting polymers

Understanding morphology-mobility dependence in PEDOT:Tos

Room Temperature Sensing Achieved by GaAs Nanowires and oCVD Polymer Coating

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