Showing papers on "Conductive polymer published in 2002"
TL;DR: Conjugated polymers and indium arsenide–based nanocrystals were used to create near-infrared plastic light-emitting diodes that effectively covers the short-wavelength telecommunications band.
Abstract: Conjugated polymers and indium arsenide–based nanocrystals were used to create near-infrared plastic light-emitting diodes. Emission was tunable from 1 to 1.3 micrometers—a range that effectively covers the short-wavelength telecommunications band—by means of the quantum confinement effects in the nanocrystals. The external efficiency value (photons out divided by electrons in) is ∼0.5% (that is, >1% internal) and is mainly limited by device architecture. The near-infrared emission did not overlap the charge-induced absorption bands of the polymer.
1,286 citations
TL;DR: In this article, aniline hydrochloride was oxidized with ammonium peroxydisulfate in aqueous medium at ambient temperature and the electrical conductivity of polyaniline was measured at room temperature.
Abstract: Eight persons from five institutions in different countries carried out polymerizations of aniline following the same preparation protocol. In a "standard" procedure, aniline hydrochloride was oxidized with ammonium peroxydisulfate in aqueous medium at ambient temperature. The yield of polyaniline was higher than 90% in all cases. The electrical conductivity of polyaniline hydrochloride thus prepared was 4.4 1.7 S cm(-1) (average of 59 samples), measured at room temperature. A product with defined electrical properties could be obtained in various laboratories by following the same synthetic procedure. The influence of reduced reaction temperature and increased acidity of the polymerization medium on polyaniline conductivity were also addressed. The conductivity changes occurring during the storage of polyaniline were monitored. The density of polyaniline hydrochloride was 1.329 g cm(-3). The average conductivity of corresponding polyaniline bases was 1.4 x 10(-8) S cm(-1), the density being 1.245 cm(-3). Additional changes in the conductivity take place during storage. Aging is more pronounced in powders than in compressed samples. As far as aging effects are concerned, their assessment is relative. The observed reduction in the conductivity by similar to10% after more than one-year storage is large but, compared with the low conductivity of corresponding polyaniline (PANI) base, such a change is negligible. For most applications, an acceptable level of conductivity may be maintained throughout the expected lifetime.
1,224 citations
TL;DR: π-Conjugated polymers that are electrochemically cycled in ionic liquids have enhanced lifetimes without failure and fast cycle switching speeds and anions such as tetrafluoroborate or hexafluorophosphate showed negligible loss in electroactivity.
Abstract: π-Conjugated polymers that are electrochemically cycled in ionic liquids have enhanced lifetimes without failure (up to 1 million cycles) and fast cycle switching speeds (100 ms). We report results for electrochemical mechanical actuators, electrochromic windows, and numeric displays made from three types of π-conjugated polymers: polyaniline, polypyrrole, and polythiophene. Experiments were performed under ambient conditions, yet the polymers showed negligible loss in electroactivity. These performance advantages were obtained by using environmentally stable, room-temperature ionic liquids composed of 1-butyl-3-methyl imidazolium cations together with anions such as tetrafluoroborate or hexafluorophosphate.
1,092 citations
TL;DR: In this paper, the optoelectronic properties of single-walled carbon nanotubes (SWNTs) composites were studied using absorption spectroscopy and electrical characterization methods, and the results showed that conjugated polymer-SWNT composite represents an alternative class of organic semiconducting material that is promising for organic photovoltaic cells with improved performance.
Abstract: We report the optoelectronic properties occurring in single-walled carbon nanotubes (SWNTs)—conjugated polymer, poly(3-octylthiophene) composites. Composite films were drop or spin cast from a solution on indium–tin oxide (ITO) and quartz substrates and studied using absorption spectroscopy and electrical characterization methods. Diodes (Al/polymer-nanotube composite/ITO) with a low nanotube concentration (<1%) show photovoltaic behavior, with an open circuit voltage of 0.7–0.9 V. The short circuit current is increased by two orders of magnitude compared with the pristine polymer diodes and the fill factor also increases from 0.3 to 0.4 for the nanotube/polymer cells. It is proposed that the main reason for this increase is the photoinduced electron transfer at the polymer/nanotube interface. The results show that the conjugated polymer-SWNTs composite represents an alternative class of organic semiconducting material that is promising for organic photovoltaic cells with improved performance.
834 citations
TL;DR: In this paper, the use of carbon black (CB) as a conductive filler in polymers and polymer blends is discussed. And several percolation models applicable to CB/polymer blends are reviewed.
Abstract: The objective of this article was to review the use of carbon black (CB) as a conductive filler in polymers and polymer blends. Important properties of CB related to its use in conducting polymers are discussed. The effects of polymer structure, molecular weight, surface tension, and processing conditions on electrical resistivity and physical properties of composites are discussed. Several percolation models applicable to CB/polymer blends are reviewed. Emphasis is placed on recent trends using polymer blends as the matrix to obtain conducting composites at a lower CB loading. A criterion for the distribution of CB in polymer blends is discussed. © 2002 Wiley Periodicals, Inc. Adv Polym Techn 21: 299–313, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/adv.10025
765 citations
TL;DR: In this article, the authors discuss synthetic routes to principal conjugated polymers such as poly(acetylene), polyheterocyclic polymers, poly( p -phenylene vinylene)s, aromatic poly(azomethine)s and poly(aniline) with special emphasis on the preparation of solution (and in some cases thermally) processible polyconjugated systems.
706 citations
643 citations
TL;DR: In this paper, the supercapacitive properties of electrochemically grown composite films of multiwalled carbon nanotubes (MWNT) and polypyrrole (PPy), a conducting polymer, were reported.
Abstract: This work reports the supercapacitive properties of electrochemically grown composite films of multiwalled carbon nanotubes (MWNT) and polypyrrole (PPy), a conducting polymer. Scanning electron microscopy, cyclic voltammetry, and electrochemical impedance spectroscopy revealed that the nanoporous three-dimensional arrangement of PPy-coated MWNTs in these films facilitated improved electron and ion transfer relative to pure PPy films. The low-frequency capacitance was measured for films of varying thickness, revealing specific capacitances per mass (Cmass) and geometric area (Carea) as high as 192 F g-1 and 1.0 F cm-2, respectively. Rates of charge and discharge about an order of magnitude faster than similarly prepared pure PPy films were also observed.
558 citations
TL;DR: In this article, polyaniline doped with HCl and LiPF6 (Pani-LiPF6) is used as the active electrode material of symmetric redox supercapacitors.
519 citations
487 citations
TL;DR: In this article, a short survey of technological aspects of electrochromism with various electroactive species is given, and some promising results with the commercially available electrically conducting polymer Baytron P (PEDT/PSS) are presented.
Abstract: A short survey of technological aspects of electrochromism with various electroactive species is given. Different approaches with inorganic and organic materials have been pursued in the past. So far widespread usage of this technology for large area applications has not been achieved. Nevertheless one major technical product, self-darkening rear-view mirrors for cars, is already well established. This article reviews some research results on electroactive polythiophenes, especially poly(3,4-alkylenedioxythiophenes). Some promising results with the commercially available electrically conducting polymer Baytron P (PEDT/PSS) are presented. It is demonstrated that an all solid-state electrochromic multilayer assembly based on a polymeric electrochromic material might be close to technical realization. The coating of large area substrates with aqueous poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) dispersion can be a way to an economically viable product.
TL;DR: In this article, the performance data of conventional and especially designed thiophene-based conducting polymers for use as positive and negative electrodes in n/p type supercapacitors is summarized.
TL;DR: In this paper, the authors report on the fabrication and characterization of an OLED device made using a highly conductive form of PEDOT:PSS as anode and demonstrate its superior performance relative to that of a similar device using the commercial conducting polymer as an anode.
Abstract: Films fabricated from commercially available poly(3,4-ethylenedioxythiophene) poly(styrenesulfonate) (PEDOT:PSS) aqueous dispersions have been widely used in many electronic and optoelectronic applications. Previous attempts to utilize them as anodes in organic light-emitting diodes (OLEDs) were not satisfactory due to their low conductivity. In this letter we report on the fabrication and characterization of an OLED device made using a highly conductive form of PEDOT:PSS as anode and demonstrate its superior performance relative to that of a similar device using the commercial conducting polymer as an anode. An external electroluminescence quantum efficiency of ∼0.73% was measured at 100 A/m2.
TL;DR: In this paper, a technique for direct writing of polymer nanostructures on insulating and semiconducting surfaces based on Electrochemical Dip-Pen Nanolithography (E-DPN) is described.
Abstract: A new technique for direct-writing of polymer nanostructures on insulating and semiconducting surfaces based on Electrochemical Dip-Pen Nanolithography (E-DPN) is described. The technique is based on electrochemical polymerization of monomers directly underneath the AFM tip. Sub-50 nm poly-3,4-ethylenedioxythiophene lines can be easily created. Such capability to direct-write and pattern polymeric materials with interesting electronic and electrooptical properties at the nanoscale creates a number of opportunities since a large variety of monomers are available.
TL;DR: In this paper, a method to measure the composite coloration efficiency of organic electrochromic polymers at 95% of the total optical density change measured at λmax was presented.
Abstract: We report a method to measure the composite coloration efficiency of organic electrochromic polymers at 95% of the total optical density change measured at λmax. This practical method is useful for the comparison of organic polymers as well as inorganic electrochromic oxides and for gaining insights into the reasons for increased efficiencies in organic polymer systems. Three polymers from the family of the poly(3,4-alkylenedioxythiophenes) (PXDOTs) were chosen, due to their well-behaved electrochromic properties, to develop the tandem chronoabsorptometry/chronocoulometry method. Coloration efficiencies were measured by monitoring the amount of injected/ejected charge as a function of the change in optical density of the polymer film. The results of these experiments revealed a significant relationship between structure and coloration efficiency determined at λmax in organic polymers. Poly(3,3-dimethyl-3,4-dihydro-2H-thieno[3,4-b]dioxepine) (PProDOT-Me2) possessed the highest coloration efficiency (375 cm...
TL;DR: In this paper, a study on the interaction between single-walled carbon nanotubes (SWNTs) and the soluble polymer poly(3-octylthiophene) (P3OT) is presented.
TL;DR: In this paper, the effects of the chemical or the electrochemical polymerization conditions on the properties of the resulting composite such as surface morphology, electrical conductivity, environmental stability, and electromagnetic interference shielding effectiveness (EMI SE) were investigated.
TL;DR: In this article, the authors showed that the necessary control over the color, brightness, and environmental stability of an electrochromic window can be achieved through the careful design of anodically coloring polymers.
Abstract: The ability to match two complementary polymers constitutes an important step forward in the design of electrochromic devices (ECDs). Here we show that the necessary control over the color, brightness, and environmental stability of an electrochromic window can be achieved through the careful design of anodically coloring polymers. For this purpose, we have constructed ECDs based on dimethyl substituted poly(3,4-propylenedioxythiophene) (PProDOT-Me2) as a cathodically coloring layer, along with poly[3,6-bis(2-ethylenedioxythienyl)-N-methyl-carbazole] (PBEDOT-NMeCz) and N-propane sulfonated poly(3,4-propylenedioxypyrrole) (PProDOP−NPrS) as anodically coloring polymers. Comparison of the results shows that using PProDOP−NPrS as the high band gap polymer has several advantages over the carbazole counterpart. The main benefit is the opening of the transmissivity window throughout the entire visible spectrum by moving the π−π* transition of the neutral anodically coloring material into the ultraviolet region. ...
TL;DR: In this paper, the authors proposed a double-cable polymeric (DCP) alternative to conjugated polymer/fullerene composites to control both electronic and morphological properties at once.
Abstract: Conjugated polymers are used increasingly for the fabrication of electronic and optoelectronic devices like light emitting diodes (LEDs) and photovoltaic (PV) elements. A breakthrough in realising a promisingly efficient conversion of solar energy into electrical energy has been achieved by using blends of soluble electron-donor type conjugated polymers with fullerenes as electron-acceptor, transporting component. This “bulk heterojunction” approach suggests the preparation of intrinsically bipolar materials as a way to control both electronic and morphological properties at once. On these bases, the covalent grafting of fullerene moieties to conjugated backbones seems promising for the preparation of intrinsically bipolar polymeric materials (double-cable polymers) alternative to conjugated polymer/fullerene composites. The recent developments on the design, the characterisation and the application of this novel class of
fullerene functional materials are reviewed.
TL;DR: Using soluble polymers for the active layer and insulating layer, a concept for the fabrication of fast integrated circuits based on p-type organic transistors only is reported in this paper, where ring oscillators with frequencies above 100 kHz and propagation stage delays below 0.7 μs are presented.
Abstract: Using soluble polymers for the active layer and insulating layer, we report on a concept for the fabrication of fast integrated circuits based on p-type organic transistors only. Ring oscillators with frequencies above 100 kHz and propagation stage delays below 0.7 μs are presented. They show a very stable performance over time even without encapsulation, when stored and measured under ambient conditions. Regioregular poly(3-alkylthiophen) is used as the active semiconducting layer, a polymer blend as the insulator, a flexible polyester film as the substrate and metal electrodes. To enable vertical interconnects, the insulating layer is patterned.
TL;DR: Novel electrochemical transistors, based on the conductive polymer PEDOT, operating at driving voltages of only a few volts in bulk material, and with little demand on substrate planarity, are described in this paper.
Abstract: Novel electrochemical transistors, based on the conductive polymer PEDOT, operating at driving voltages of only a few volts in bulk material, and with little demand on substrate planarity, are desc ...
TL;DR: In this paper, the response time of pure polyaniline (PAN) and polystyrenesulfonic acid (PSSA) composite films with various number of layers was investigated.
Abstract: Pure polyaniline (PAN) film, polyaniline and acetic acid (AA) mixed film, as well as PAN and polystyrenesulfonic acid (PSSA) composite film with various number of layers were prepared by Langmuir–Blodgett (LB) and self-assembly (SA) techniques. These ultra-thin films were characterized by ultraviolet–visible (UV–VIS) spectroscopy and ellipsometry. It is found that the thickness of PAN-based ultra-thin films increases linearly with the increase of the number of film layers. The gas-sensitivity of these ultra-thin films with various layers to NO 2 was studied. It is found that pure polyaniline films prepared by LB technique had good sensitivity to NO 2 , while SA films exhibited faster recovery property. The response time to NO 2 and the relative change of resistance of ultra-thin films increased with the increase of the number of film layers. The response time of three-layer PAN film prepared by LB technique to 20 ppm NO 2 was about 10 s, two-layer SA film was about 8 s. The mechanism of sensitivity to NO 2 of PAN-based ultra-thin films was also discussed.
TL;DR: In this article, the authors investigated the in-situ conductivity of poly(2,7-carbazole)s and showed that the presence of a strong electron-withdrawing substituent onto the nitrogen atom in the homopolymer leads to an increase by 3 orders of magnitude of the conductivity.
Abstract: Novel poly(2,7-carbazole)s (i.e., poly(N-octyl-2,7-carbazolediyl) and poly(N-(4-hexylbenzoyl)-2,7-carbazolediyl)) and their alternating thiophene, bithiophene, and 3,4-ethylenedioxy-2,5-thienylene copolymers have been investigated by cyclic voltammetry, UV−vis spectroelectrochemistry, electrochemical quartz crystal microbalance, in-situ electron spin resonance, and in-situ conductivity techniques. All polymer films undergo reversible oxidation and partially reversible reduction processes. In poly(N-octyl-2,7-carbazolediyl), two isoelectronic oxidation processes produce radical cations and dications with charge localization at the carbazole subunits. The presence of a strong electron-withdrawing substituent onto the nitrogen atom in the homopolymer leads to an increase by 3 orders of magnitude of the conductivity (i.e., 1 × 10-2 S/cm). Similarly, in alternating copolymers, the oxidative charge is more delocalized over the polyconjugated backbone with in-situ conductivities in the range of 4 × 10-2−4 × 10-3...
TL;DR: In this paper, conductive polyaniline nanowires in emeraldine form can be deposited by potentiodynamic electropolymerization from a reverse hexagonal liquid crystalline phase where one-dimensional aqueous channels can serve as space-confined reactors.
Abstract: Conductive polyaniline nanowires in emeraldine form can be deposited by potentiodynamic electropolymerization from a reverse hexagonal liquid crystalline phase where one-dimensional (1D) aqueous channels can serve as space-confined reactors. Polyaniline nanowire bundles with single-wire diameter of 50–70 nm and length of several microns were obtained from surfactant sodium bis(2-ethylhexyl) sulfosuccinate (AOT) reverse hexagonal liquid crystalline phase. Impedance measurement suggests improved ordering of the reverse hexagonal liquid crystal under external electric field during the electropolymerization process. This enhanced ordering appears essential for the nanowire growth. The nanowires obtained can be easily collected by a simple washing process.
TL;DR: In this paper, a schemaric representation of a polyrotaxane is presented, where a polymer is threaded into a host tube and held in place by end caps, and an end cap is used to separate polymer chains to inhibit interchain effects.
Abstract: Conjugated polymers have en enormous range of potential applications, and recent work shows how many of these can be realrzed practically. Encapsulation can offer advantages in terms of separating polymer chains to inhibir interchain effects, improving the mechanical, thermal, and chemical stabilities of the assemblies, and possibly allowing individual molecular wires to be addressed. The Figure shows a schemaric representation of a polyrotaxane, i.e., a polymer threaded into a host tube and held in place by end caps.
TL;DR: In this article, the effect of synthetic conditions, such as the molar ratio of D-CSA to aniline (An), the concentration of D -CSA in the polymerization media, the reaction temperature and time, on the morphology and size as well as the electrical properties of the PANI-(CSA) was investigated.
Abstract: Conducting nanotubes of polyaniline (PANI) about 80–180 nm in diameter were synthesized by a chemical template-free method in the presence of D-10-camphorsulfonic acid (D-CSA) as the dopant, and ammonium persulfate ((NH4)2S2O8) as the oxidant. The effect of synthetic conditions, such as the molar ratio of D-CSA to aniline (An), the concentration of D-CSA in the polymerization media, the reaction temperature and time, on the morphology and size as well as the electrical properties of the PANI–(D-CSA) was investigated. It was found that the above synthetic conditions, especially the molar ratio of D-CSA to An, strongly affected the morphology and formation probability of the resulting PANI. The micelles formed by D-CSA and anilinium cations act as the templates in the formation of PANI–(D-CSA) nanotubes.
TL;DR: In this article, a hybrid material of carbon nanotubes (CNTs) and polyaniline (PANI) was prepared by in situ emulsion polymerization and structural characterization showed that some CNTs were linked up by PANI chains.
TL;DR: In this article, the application of these conducting tubes in the development of amperometric glucose sensors is discussed, and they are shown to have enhanced electrical properties compared to their corresponding bulk materials.
Abstract: Organic conducting polymers can be synthesized inside the pores of a track-etch membrane, and the resulting hollow tubules are shown to have enhanced electrical properties compared to their corresponding bulk materials. The polymerization of monomers (e.g., pyrrole, thiophenes) inside the confined space of these pores, combined with electrostatic interaction, ensures the alignment of the organic polymers on the interior, leading to higher conductivity. The application of these conducting tubes in the development of amperometric glucose sensors is discussed. Due to the special properties of conducting polymers inside a track-etch membrane, biosensors with a unique electron-transfer mechanism have been developed.