The electroactive multilayer films of polyelectrolytes and Prussian blue nanoparticles and their application for H2O2 sensors

Prussian blue (PB) nanoparticles were immobilized in polyelectrolyte (PE) multilayers of various compositions and thickness. Films containing nanoparticles and poly(allylamine hydrochloride) (PAH) were formed using the layer-by-layer adsorption method. A layer of branched poly(ethyleneimine) (PEI) was used to anchor the multilayer structure at the surface of a gold electrode. The films exhibited electroactive properties, increasing with the number of deposited PB layers. The properties of PEI/(PB/PAH) _n multilayers were then compared with the ones containing additionally the conductive polymer poly(3,4-ethylenedioxythiophene)–poly(styrenesulfonate) (PEDOT:PSS). We found that the addition of the conductive, water-soluble polymer enhances the electroactive properties of the multilayer films. It also increased sensitivity of the multilayer-covered electrodes for electrochemical detection of hydrogen peroxide.     

Electrocatalysis of 2,5-dimercapto-1,3,5-thiadiazole by 3,4-ethylenedioxy-substituted conducting polymers

The electronic properties of electropolymerized films of the 3,4-ethylenedioxy-substituted conducting polymers (CP) poly(3,4-ethylenedioxythiophene) (PEDOT), poly(3,4-ethylenedioxypyrrole) (PEDOP) and poly(3,4-ethylenedioxyselenophene) (PEDOS) have been investigated, along with their electrocatalytic activity toward 2,5-dimercapto-1,3,4-thiadiazole (DMcT). For the electropolymerized films, the conductivity onset potential was most negative for PEDOP (-1.50 V), followed by PEDOS (-1.35 V) and with PEDOT possessing the most positive onset (-1.15 V). The heterogeneous charge transfer rate constant for DMcT in solution at polymer-film-modified glassy carbon electrodes (GCEs) was studied. It was found that compared to PEDOP, both PEDOS and PEDOT performed better as electrocatalysts, with PEDOS having a heterogeneous charge transfer rate constant of 1.8 × 10(-3) cm/s. The film morphology of the electropolymerized films was investigated via SEM, and some film characteristics could be correlated with electrocatalytic activity. The potential use of CP/DMcT composites for lithium ion batteries (LIBs) is discussed.     

All-solid-state reference electrodes based on conducting polymers

A novel construction of solution free (pseudo)reference electrodes, compatible with all-solid-state potentiometric indicator electrodes, has been proposed. These electrodes use conducting polymers (CP): polypyrrole (PPy) or poly(3,4-ethylenedioxythiophene) (PEDOT). Two different arrangements have been tested: solely based on CP and those where the CP phase is covered with a poly(vinyl chloride) based outer membrane of tailored composition. The former arrangement was designed to suppress or compensate cation- and anion-exchange, using mobile perchlorate ions and poly(4-styrenesulfonate) or dodecylbenzenesulfonate anions as immobilized dopants. The following systems were used: (i) polypyrrole layers doped simultaneously by two kinds of anions, both mobile and immobilized in the polymer layer; (ii) bilayers of polypyrrole with anion exchanging inner layer and cation-exchanging outer layer; (iii) polypyrrole doped by surfactant dodecylbenzenesulfonate ions, which inhibit ion exchange on the polymer/solution interface. For the above systems, recorded potentials have been found to be practically independent of electrolyte concentration. The best results, profound stability of potentials, have been obtained for poly(3,4-ethylenedioxythiophene) or polypyrrole doped by poly(4-styrenesulfonate) anions covered by a poly(vinyl chloride) based membrane, containing both anion- and cation-exchangers as well as solid potassium chloride and silver chloride with metallic silver. Differently to the cases (i)-(iii) these electrodes are much less sensitive to the influence of redox and pH interferences. This arrangement has been also characterized using electrochemical impedance spectroscopy and chronopotentiometry.     

Crown-tetrathiafulvalenes attached to a pyrrole or an EDOT unit: synthesis, electropolymerization and recognition properties

A crown-tetrathiafulvalene electroactive receptor has been covalently linked to electropolymerizable pyrrole or 3,4-ethylenedioxythiophene monomers. The synthetic route to the monofonctionalized tetrathiafulvalene (TTF) ligand has been optimized. Two derivatives of pyrrole (N- and 3-substituted) were synthesized. The various substituted monomers have been electropolymerized to produce polypyrrole (PP) and poly(ethylenedioxothiophene) (PEDOT) films bearing the electroactive TTF moiety. The electroactivity of the polymer films is efficiently controlled by the well-defined two-step redox behavior of the TTF unit. In the case of PEDOT, an alternative post-polymerization derivatization strategy has been used, involving the grafting of the crown-TTF ligand on the previously grown PEDOT backbone. Though chemical derivatization is realized under heterogeneous conditions, in the bulk of the film, this strategy proved to be particularly efficient. These electrodes constitute the first examples of conducting polymer-based modified electrodes incorporating a TTF electrochemical probe, able to interact with a guest ion, such as Ba2+. The cation recognition properties of these various electrodes have been analyzed by cyclic voltammetry and their electroactivity in water as well as their regeneration capability have been investigated.     

Water uptake in the hydrophilic poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) solid-contact of all-solid-state polymeric ion-selective electrodes

Solid-contact (SC) ion-selective electrodes (ISEs) utilizing thin films of poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) and plasticized poly(vinylchloride) (PVC) have been produced using a spin casting procedure. This study was carried out with a view of characterizing this popular and well known SC ISE using a series of complementary surface analysis techniques. This work revealed that PEDOT:PSS prevents the separation of an undesirable water layer at the buried interface of this SC ISE due to the high miscibility of water in the hydrophilic PEDOT:PSS layer. The lack of a clearly defined and molecularly sharp buried interface prohibits the formation of a distinct water layer presumably by eliminating sites that promote the accumulation of water. This outcome is important to the chemical sensor community since it provides further insights into the compatibility of sensor components in SC ISEs.     

Novel electroluminescent cationic polyelectrolyte based on poly[(fluorene‐2,7‐diylvinylene)‐alt‐(1,4‐phenylenevinylene)] and its precursor

A novel conjugated poly[(fluorene‐2,7‐vinylene)‐alt‐(1,4‐phenylenevinylene)] derivative 2 with quaternizable tertiary amino groups was synthesized by Heck coupling of a substituted 2,7‐dibromofluorene and 1,4‐dialkoxy‐2,5‐divinylbenzene. The corresponding quaternary ammonium cationic polyelectrolyte 3 was obtained by the treatment of 2 with bromoethane. Both polymers were soluble in common organic solvents, like tetrahydrofuran, chloroform, and dichloromethane. Polymer 3 showed a limited solubility in alcohols and was insoluble in water. Photophysical and electrochemical properties of the resulting polymers were fully investigated. An intensive green photoluminescence (PL) with maxima at 550 and 545 nm was observed from thin films of 2 and 3 polymers, respectively, red‐shifted compared with the PL emission spectra measured in the solution. The electrochemical band gaps were 2.38–2.45 eV. Single‐layer and double‐layer (with poly[3,4‐(ethylenedioxy)thiophene]/poly (styrenesulfonate) (PEDOT:PSS)) light‐emitting devices (LEDs) with ITO and Al electrodes were prepared and studied. They emitted a green light and their electroluminescence (EL) spectra were similar to those of PL thin films. The external EL efficiency was determined to be 0.43 and 0.32% for ITO/PEDOT:PSS/ 2 /Al and ITO/PEDOT:PSS/ 3 /Al LEDs, respectively. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 1016–1027, 2007     

基于WOx/PEDOT:PSS复合空穴传输层的高效稳定平面异质结钙钛矿太阳电池

在基于钙钛矿/富勒烯平面异质结的钙钛矿太阳电池中,PEDOT:PSS是最常使用的空穴传输材料. 但PEDOT:PSS呈酸性,会腐蚀金属氧化物透明电极,使器件的电极界面稳定性欠佳. 本文将高功函的氧化钨（WO_x）插入到PEDOT:PSS和FTO之间,形成WO_x/PEDOT:PSS复合空穴传输层,这样既可以避免PEDOT:PSS与FTO直接接触,提高器件的稳定性,又可以进一步降低电极界面的接触势垒,从而提升器件的性能. 作者研究了复合传输层对透光率、钙钛矿形貌、钙钛矿结晶、光伏性能及器件稳定性的影响. 基于WO_x/PEDOT:PSS复合空穴传输层的电池效率可以达到12.96%,比单纯的PEDOT:PSS的电池效率(10.56%)提升了22.7%,同时器件的稳定性也得到大幅改善.     

Fabrication of organic thin-film transistors using layer-by-layer assembly

Layer-by-layer assembly is presented as a deposition technique for the incorporation of ultrathin gate dielectric layers into thin-film transistors utilizing a highly doped organic active layer. This deposition technique enables the fabrication of device structures with a controllable gate dielectric thickness. In particular, devices with a dielectric layer comprised of poly(allylamine hydrochloride)/poly(acrylic acid) (PAH/PAA) bilayer films were fabricated to examine the properties of poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) as the transistor active layer. The transistor Ion/off ratio and switching speed are shown to be controlled by the gate bias, which is dependent upon the voltage applied and the number of bilayers deposited for the gate dielectric. The devices operate in the depletion mode as a result of dedoping of the active layer with the application of a positive gate bias. The depletion and recovery rate are highly dependent on the level of hydration in the film and the environment under which the device is operated. These observations are consistent with an electrochemical dedoping of the conducting polymer during operation.     

All-solid-state carbonate-selective electrode based on a molecular tweezer-type neutral carrier with solvent-soluble conducting polymer solid contact

Carbonate-selective membranes were prepared by incorporating a molecular tweezer-type carbonate-selective neutral carrier [N,N-dioctyl-3alpha,12alpha-bis(4-trifluoroacetylbenzyloxy)-5beta-cholan-24-amide] into a room temperature vulcanizing-type silicone rubber (3140 RTV-SR) matrix, and deposited on the planar-type electrodes (Pt containing Ag/AgCl electrodes formed on a ceramic plate) with and without an intermediary conducting polymer layer. Two types of solvent-soluble conducting polymers [poly(1-hexyl-3,4-dimethyl-2,5-pyrrolylene) or poly(3-octylthiophene-2,5-diyl)] have been examined as the solid contact material. Potentiometric properties of the resultant all-solid-state electrodes were evaluated in terms of their carbonate selectivity, response slope, potential stability and reproducibility. The sensitivity and carbonate selectivity of the SR membrane-based all-solid-state electrodes with conducting polymer solid contact were comparable to those of conventional electrodes. Experimental results also showed that the intermediary conducting polymer layer used in the all-solid-state electrodes greatly reduces the interference from dissolved oxygen.     

导电聚合物有序超薄膜的合成及其作为有机电致发光器件空穴注入层

采用修饰多层LB膜的方法制备了导电聚合物聚-3,4-乙烯二氧噻吩/二十烷酸(PEDOT:AA)复合层状有序膜, 构筑了一种导电聚合物镶嵌的多层有序膜结构. 将这种导电聚合物有序薄膜沉积于ITO电极表面, 将其作为有机电致发光二极管(OLED)的空穴注入层, 并研究了ITO/(PEDOT:AA)/MEH-PPV/Al器件的性能. 研究结果表明, 与采用聚3,4-乙烯二氧噻吩/聚苯乙烯磺酸(PEDOT:PSS)自组装膜和旋涂膜作为空穴注入层的ITO/(PEDOT:PSS)/MEH-PPV/Al器件相比, 器件的发光效率增加, 起亮电压降低. 我们认为这是由于PEDOT:AA薄膜提供了一种有序层状结构后, 减小了ITO与MEH-PPV间的接触势垒, 改善了空穴载流子注入效率. 进一步的研究表明, 由于PEDOT:AA多层膜间靠较弱的亲水、疏水作用结合, 这种导电多层有序膜的热稳定性与普通LB膜相似, 在较高温度下发生从层状有序态到无序态的变化, 这是导致OLED器件性能发生劣化的主要原因.     

改善有机光伏器件性能的新型缓冲层

通过热蒸发在ITO阳极和聚3,4-乙撑二氧噻吩:聚苯乙烯磺酸(PEDOT:PSS)层之间引入一层聚四氟乙烯（PTFE）缓冲层,研究聚四氟乙烯缓冲层对基于聚3-己基噻吩:6,6-苯基-C61丁酸甲酯(P3HT:PCBM)的有机光伏器件光电特性影响。与使用PEDOT:PSS作为缓冲层的器件相比,使用聚四氟乙烯缓冲层的有机光伏器件开路电压、短路电流和光电转换效率均有所提高。器件光电性能提高的原因是由于PTFE缓冲层大量带负电荷的氟离子在ITO/PTFE界面处形成偶极子层, 改善了内建电场,从而使得空穴电荷的收集更加有利。     

Increased spherulitic growth rates of semicrystalline polymer due to enhanced limited local chain segmental mobility at the interface of double-layer thin films

In this work the nucleation and growth of spherulites for the below polylactide (PLA) layer in poly(ε-caprolactone)/polylactide (PCL/PLA) double-layer films during isothermal crystallization at various temperatures above the melting point of PCL have been investigated by using polarized optical microscopy (POM). It is revealed that two types of spherulitic morphologies are observed in PCL/PLA double-layer films. One is the well defined highly birefringent spherulites, and the other one is the coarse spherulites. It is interesting to find that the spherulitic growth rate of the coarse spherulites is higher than that of the well defined spherulites. It is thought that the coarse spherulites nucleate and grow with the assistance of the interfaces between the PCL and PLA layers, and the well defined highly birefringent spherulites only nucleate and grow in the PLA layer.     

Nitrite Oxidation with Copper–Cobalt Nanoparticles on Carbon Nanotubes Doped Conducting Polymer PEDOT Composite

Copper–cobalt bimetal nanoparticles (Cu?Co) have been electrochemically prepared on glassy carbon electrodes (GCEs), which were electrodeposited with conducting polymer nanocomposites of poly(3,4‐ethylenedioxythiophene) (PEDOT) doped with carbon nanotubes (CNTs). Owing to their good conductivity, high mechanical strength, and large surface area, the PEDOT/CNTs composites offered excellent substrates for the electrochemical deposition of Cu?Co nanoparticles. As a result of their nanostructure and the synergic effect between Cu and Co, the Cu?Co/PEDOT/CNTs composites exhibited significantly enhanced catalytic activity towards the electrochemical oxidation of nitrite. Under optimized conditions, the nanocomposite‐modified electrodes had a fast response time within 2 s and a linear range from 0.5 to 430 μm for the detection of nitrite, with a detection limit of 60 nm . Moreover, the Cu?Co/PEDOT/CNTs composites were highly stable, and the prepared nitrite sensors could retain more than 96 % of their initial response after 30 days.     

Time-scale- and temperature-dependent mechanical properties of viscoelastic poly(3,4-ethylenedioxythiophene) films

The viscoelastic properties of thin films of poly(3,4-ethylenedioxythiophene) (PEDOT) have been studied using the method of acoustic impedance. The films were deposited on the Au electrodes of 10 MHz AT-cut quartz thickness shear mode resonators and exposed to acetonitrile solutions of 0.1 M TEABF4 and LiClO4. For p-doped films, admittance spectra as a function of potential (E), temperature (T), and time scale (frequency, via harmonics, in the range 10-110 MHz) were acquired. Shear modulus components extracted from these responses surprisingly showed virtually no variation with E (and thus film solvation) or with T, but the variation with frequency was dramatic. This qualitative behavior and the numerical values of the shear moduli contrast strongly with recently reported data for the related poly(3-hexylthiophene) system, which shares the same conducting spine but differs substantially in the substitution pattern. Accordingly, the models and interpretation for PEDOT are quite different: film dynamics are determined by free-volume effects, and side-chain motion is not a significant factor. Qualitatively similar potential and time-scale effects were seen for n-doped PEDOT, but the scope of the measurements was limited by film stability.     

Electrochemical synthesis of PEDOT and PPP macroporous films and nanowire architectures from ionic liquids

We report on the electrochemical synthesis of macroporous films and on nanowire architectures of conducting polymers from ionic liquids. The electrodeposition of poly(3,4-ethylenedioxythiophene) (PEDOT) and of poly(para-phenylene) (PPP) from the air and water stable ionic liquids 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)amide ([EMIm]TFSA) and from 1-hexyl-3-methylimidazolium tris(pentafluoroethyl)trifluorophosphate ([HMIm]FAP) within the voids of a polystyrene opal structure on gold and on platinum substrates yield macroporous films. For this purpose, polystyrene spheres with an average diameter of about 600?nm were applied onto the employed electrodes by a simple dipping process resulting in a layer thickness of about 10?μm. The macroporous films turn into yellow, orange, blue, and green colors owing to the Bragg reflection of the incident artificial white light. PPP and PEDOT nanowires were electrochemically prepared in a track-etched polycarbonate (PC) membrane with an average pore diameter of 90?nm. One side of the membrane was sputtered with a thin gold film to serve as a working electrode. Electrodeposition occurs along the pores of the template. Nanowires with an average diameter of 90?nm and a length of up to 17?μm can be easily synthesized by this electrochemical template-assisted method. Such materials are of interest as catalyst in metal/air batteries and as cathode material in, e.g., microbatteries.     

Stable aqueous dispersion of reduced graphene nanosheets via non-covalent functionalization with conducting polymers and application in transparent electrodes

We developed a simple and facile method of producing a stable aqueous suspension of reduced graphene oxide (RGO) nanosheets through the chemical reduction of graphene oxide in the presence of a conducting polymer dispersant, poly(3,4-ethylene dioxythiophene):poly(styrene sulfonate) (PEDOT:PSS). This approach involves the cooperative interactions of strong π- π interactions between a two-dimensional graphene sheet and a rigid backbone of PEDOT and the intermolecular electrostatic repulsions between negatively charged PSS bound on the RGO sheets, which impart the colloidal stability of the resulting hybrid nanocomposite of RGO/PEDOT. Moreover, our one-step solution-based method allows preserving the intrinsic chemical and electronic properties of both components, yielding a hybrid film of RGO nanosheets of high conductivity of 2.3 kΩ/sq with a transmittance of 80%. By taking advantage of conducting network structure of conducting polymers which provides an additional flexibility and mechanical stability of RGO nanosheets, we demonstrate the potential application of hybrid RGO/PEDOT as highly flexible and transparent electrodes.     

Effective charge propagation and storage in hybrid films of tungsten oxide and poly(3,4-ethylenedioxythiophene)

Hybrid (composite) electroactive films consisting of such an organic conducting polymer as poly(3,4-ethylenedioxythiophene), PEDOT, and such a polynuclear inorganic compound as amorphous tungsten oxide, WO₃/H _x WO₃ were fabricated on carbon electrodes through electrodeposition by voltammetric potential in acid solution containing EDOT monomer and sodium tungstate. Electrostatic interactions between the negatively charged tungstic units (existing within WO₃) and the oxidized positively charged conductive polymer (oxidized PEDOT) sites create a robust hybrid structure which cannot be considered as a simple mixture of the organic and inorganic components. It is apparent from scanning electron microscopy that hybrid structures are granular but fairly dense. Because PEDOT and mixed-valence tungsten oxides are electronically conducting, the resulting hybrid films are capable of fast propagation. The reversible and fast redox reactions of tungsten oxide component lie in the potential range where PEDOT matrix is conductive. Furthermore, the hybrid films exhibit good mediating capabilities towards electron transfers between model redox couples such as cationic iron(III,II) and anionic hexacyanoferrate(III,II). Since the films accumulate effectively charge and show high current densities at electrochemical interfaces, they could be of importance to electrocatalysis and to construction of redox capacitors.     

New CNT/poly(brilliant green) and CNT/poly(3,4-ethylenedioxythiophene) based electrochemical enzyme biosensors

A combination of the electroactive polymer poly(brilliant green) (PBG) or conducting polymer poly(3,4-ethylenedioxythiophene) (PEDOT) with carbon nanotubes to obtain CNT/PBG and CNT/PEDOT modified carbon film electrodes (CFE) has been investigated as a new biosensor platform, incorporating the enzymes glucose oxidase (GOx) as test enzyme, alcohol oxidase (AlcOx) or alcohol dehydrogenase (AlcDH). The sensing parameters were optimized for all biosensors based on CNT/PBG/CFE, CNT/PEDOT/CFE platforms. Under optimized conditions, both GOx biosensors exhibited very similar sensitivities, while in the case of AlcOx and AlcDH biosensors, AlcOx/CNT/PBG/CFE was found to give a higher sensitivity and lower detection limit. The influence of dissolved O₂ on oxidase-biosensor performance was investigated and was shown to be different for each enzyme. Comparisons were made with similar reported biosensors, showing the advantages of the new biosensors, and excellent selectivity against potential interferents was successfully demonstrated. Finally, alcohol biosensors were successfully used for the determination of ethanol in alcoholic beverages.     

导电高分子的最近进展

因为导电高分子结合了金属与塑料的优点,他们一直受到很大的关注。但是他们的应用受到一些因素的影响,包括他们的电学性质,稳定性和可加工性。近来,导电高分子的性能得到很大的提高。他们在许多领域的重要应用被论证,比如透明电极,可拉伸电极,神经界面,热电转换和能量储存。这篇文章简单综述了导电高分子的电导提高和它们在热电转换,超级电容器和电池的应用。     

Improving the fabrication of all-polythiophene supercapacitors

The influence of the preparation method in the properties of poly(3,4-ethylenedioxythiophene) (PEDOT) electrodes used to manufacture organic energy storage devices, as for example supercapacitors, have been examined by considering a reduction of both monomer and supporting electrolyte concentrations during the anodic polymerization reaction. Thus, the excellent electrochemical properties of PEDOT films prepared using quiescent solutions have been preserved by applying controlled agitation to the polymerization process, even though the concentration of monomer and supporting electrolyte were reduced 5 and 2 times, respectively. For example, the charge stored for reversible exchange in a redox process, the electrochemical stability and the current productivity of films achieved using quiescent solutions have been preserved using a dynamic reaction medium in which the concentrations of monomer and supporting electrolyte are several times lower. The excellent properties of PEDOT electrodes prepared using optimized dynamic conditions have also been proved by constructing a symmetric supercapacitor. This energy storage device, which has been used as power source for a LED bulb, is rechargeable and exhibits higher charge-discharge capacities than supercapacitors prepared with electrodes derived from quiescent solutions. In addition of bring an efficacious procedure for preparing cost-effective PEDOT films with excellent properties, the proposed dynamic conditions reduce the environmental hazards of depleted reaction media.