EDOT Research Articles

Integrated flexible supercapacitor based on poly (3, 4-ethylene dioxythiophene) deposited on Au/porous polypropylene film/Au

Thin layers of continuous gold have been deposited on the both sides of porous polypropylene films (PPF) via electroless plating method to form a sandwich structure with two conductive surfaces and an intermediate insulating layer (Au/PPF/Au). Then poly (3, 4-ethylenedioxy thiophene) (PEDOT) layers are electrodeposited on the two conductive sides via cyclic voltammetry method to form the sandwich-structured PEDOT-Au/PPF/Au-PEDOT. Gel electrolyte of H3PO4/polyvinyl alcohol (H3PO4/PVA) is then added to the sandwich-structured PEDOT-Au/PPF/Au-PEDOT to form the integrated flexible supercapacitor of Au-PEDOT|H3PO4/PVA|PEDOT-Au. The PEDOT-Au/PPF/Au-PEDOT sandwiched structures are characterized and the capacitive performances of the integrated flexible cells are investigated in detail. The results show that the optimum integrated flexible cell exhibits excellent cycling stability (91.8% capacitance retention after 20000 cycles) and relatively high areal specific capacitance. Furthermore, the cells of Au-PEDOT|H3PO4/PVA|PEDOT-Au not only exhibit excellent bending endurance (99.1% capacitance retention after 5000 repeated bending cycles), but also can be conveniently connected in series without additional wires. This integrated flexible cell may exhibit potential application in portable electronics.

Enhancing the Performance of a Silicon Anode by Using a New Conjugated Polymer Binder Prepared by Direct Arylation

Silicon has been considered as the next-generation anode material for Li-ion batteries due to its high capacity, but suffers from isolated conducting agents due to its large volume expansion and pulverization during cycling, causing rapid decays in performance. Using conjugated polymer binders bearing functional groups that bind Si was suggested to overcome this problem due to their electronic conductivity and enhanced mechanical properties. But conjugated polymers are generally prepared via organometallic intermediates, and are hence very difficult to purify and mass produce. Here, a novel conjugated polymeric binder based on ethylene dioxythiophene (EDOT) and phenylene (EP) was prepared using direct arylation, and then characterized. Specifically, the electrically conductive EP binder showed an enhanced adhesion to Si, and the electrode made of EP showed a capacity of 2250 mAh g-1 at its 1st cycle and 670 mAh g-1 at the 50th cycle, much higher than those of the electrode made of a poly(vinylidene fluoride) (PVdF) binder.

Effect of PEDOT:PSS in tissue engineering composite scaffold on improvement and maintenance of endothelial cell function

According to recent research, smart polymers can affect different kind of mammalian cells such as endothelial cells. It is known that conductive polymers have great features, e.g. electrical conductivity, and can help increase electrical cell communication. To clarify the effect of one of these smart materials on endothelial cells, which are not inherently electrically dependent, poly(3, 4-ethylene dioxythiophene) polystyrene sulfonate (PEDOT:PSS) was chosen. Scaffolds were composed of gelatin, alginate, and PEDOT:PSS and made through solvent casting. Human umbilical vein endothelial cells (HUVECs) were cultured on the scaffold with different PEDOT:PSS concentrations. SEM, MTT assay, cell attachment, nitric oxide measurement, real-time PCR and immunohistochemistry analysis were employed to assess endothelial cell responses. Although there was no significant difference in swelling ratio, mass loss, and cell attachment when PEDOT:PSS concentration increased in scaffold construction, cell proliferation noticeably increased after seven days. The cells showed a significant increase in proliferation and NO release to the scaffold with 1% PEDOT:PSS concentration. The results indicated increases in the amount of expression of platelet endothelial cell adhesion molecule-1 (PECAM-1, CD31), kinase insert domain receptor (KDR), vascular-endothelial Cadherin (VE. Cadherin), and von Will brand factor (vWf) in the group which contained a conductive polymer in comparison with the non-conductive scaffold. Therefore, as a conductive polymer, PEDOT:PSS can affect the endothelial cell behaviours.

Efficient and stable HER electrocatalyst using Pt-nanoparticles@poly(3,4–ethylene dioxythiophene) modified sulfonated graphene nanocomposite

The green production of hydrogen by electrochemical water splitting has been recently paid attention. It is more focused to research about the preparation of efficient electrocatalysts, which catalyze hydrogen evolution reaction (HER) in acidic media at low overpotential. Platinum is known as an ideal option, but its rarity and high-cost limit its application in practical industrial plants. Hence, minimizing the level of it can be a solution. It can be achieved by the decoration of platinum nanoparticles (PtNPs) on the different composites such as poly(3,4–ethylene dioxythiophene, PEDOT) and sulfonated graphene nanosheets (SG) in this work. Accordingly, the successful preparation and HER electrocatalytic manner of this nanocomposite were main objectives in the present report. The related characterization and performance were monitored using various analytical and electrochemical techniques. The low charge transfer resistance (around 50 Ω), low overpotential (−0.040 V vs. RHE), and stable manner (until 500 cycles) resulted in this HER electrocatalyst. It was controlled by Tafel reaction with electrochemical adsorption-desorption because of kinetic factors including Tafel slope (28.4 mV dec−1), charge-transfer coefficient of 2.0, and exchange current of 7.27 mA cm−2.

MnO2-Graphene Oxide-PEDOT:PSS Nanocomposite for an Electrochemical Supercapacitor

A ternary nanocomposite with poly (3,4 ethylene dioxythiophene:poly(styrene sulfonate) (PEDOT:PSS)-MnO2 nanowires-graphene oxide (PMn-GO) was synthesized by using simple chemical route. The formation of the nanocomposite was analyzed by using X-ray diffraction and X-ray photoelectron spectroscopy. Field-emission scanning microscopy (FESEM) revealed the formation of MnO2 nanowires and graphene oxide nanosheets. The highest specific capacitance (areal capacitance) of 841 Fg −1 (177 mFcm −2) at 10 mVs −1 and energy density of 0.593 kWhkg −1 at 0.5 mA were observed for PMn-GO, indicating a constructive synergistic effect of PEDOT:PSS, MnO2 nanowires and graphene oxide. The achieved promising electrochemical characteristics showed that this ternary nanocomposite is a good alternative as an electrode material for supercapacitor.

Optical, film surface and photovoltaic properties of PTB7-Fx-based polymer-organic solar cells prepared in ambient conditions

Bulk heterojunction organic solar cells based on active layer of PTB7-Fx (x = 0–100), conjugated block copolymer incorporating benzo[1,2-b:4,5-b′]dithiophene and partly fluorinated thieno[3,4-b]thiophene units, and fullerene derivatives as phenyl C61 and phenyl C71 butyric acid methyl esters sandwiched between a transparent anode of indium tin oxide, a hole conducting layer of either poly(ethylene dioxythiophene) : polystyrene sulfonate or magnetron-sputtered molybdenum oxide and evaporated aluminum cathodes were fabricated. Polymer-organic thin films were prepared at 1:1.5 mass ratio of the donor:acceptor mixture and deposited from dichlorobenzene solution of different concentrations by spin coating in ambient conditions. To control the active layer morphology, the films were subjected either to post-deposition treatments (annealing) at different temperatures or incorporation of an additive such as diiodooctane. Optical transmission, film surface topography and thickness measurements were used to characterize the active layer. Test devices with the architecture described above were prepared and their current–voltage characteristics, quantum efficiency and impedance spectra were measured and used to compare the different active layers, architectures and deposition sequences.

Tunable hole injection of solution-processed polymeric carbon nitride towards efficient organic light-emitting diode

Polymeric carbon nitride (CNxHy) has been facilely synthesized from dicyandiamide and functions as a solution-processed hole injection layer in organic light-emitting diodes (OLEDs). The measurements using X-ray diffraction, atomic force microscopy, X-ray photoelectron spectroscopy, ultraviolet photoelectron spectroscopy, and impedance spectroscopy elucidate that CNxHy exhibits superior film morphology and extra electric properties such as tailored work function and tunable hole injection. The luminous efficiency of CNxHy-based OLED is found to improve by 76.6% in comparison to the counterpart using favorite solution-processed poly(ethylene dioxythiophene):poly(styrene sulfonate) as the hole injection layer. Our results also pave a way for broadening carbon nitride applications in organic electronics using the solution process.

Electrochemical deposition of poly[ethylene-dioxythiophene] (PEDOT) films on ITO electrodes for organic photovoltaic cells: control of morphology, thickness, and electronic properties

In this article, controlled changes on morphology, thickness, and band gap of poly[ethylenedioxythiophene] (PEDOT) polymer films fabricated by electrochemical polymerization (potentiostatically) are analyzed. Electropolymerization of the monomer ethylenedioxythiophene (EDOT) was carried out on indium tin oxide (ITO) electrodes, in different dry organic electrolytic media, such as acetonitrile, acetonitrile–dichloromethane, and toluene–acetonitrile mixtures. It was found that electropolymerization kinetics can be controlled by changing the polarity of the electrolytic media, and kinetics is slower for those with low polarity. This fact combined with an accurate control of EDOT monomer concentration and electropolymerization at Epeak/2 potential, allows to control the morphology and thickness of the electropolymerized PEDOT films (E-PEDOT:ClO4); toluene/ACN (4:1, v/v) and [EDOT] = 0.3 mM gave the best films for application in organic photovoltaic (OPV) cells. The performance of the E-PEDOT:ClO4 films was tested on ITO electrodes as anode buffer layer in OPV cells with the configuration ITO/E-PEDOT:ClO4/P3HT:PC61BM/Field’s metal, where Field’s metal (cathode) is a eutectic alloy that lets to fabricate OPV devices easily and in a fast and economical way at free vacuum conditions. The performance of these devices was compared with an OPV device constructed with a buffer layer anode, prepared using the classical spin coating of PEDOT:PSS on ITO. Results showed that OPV cells fabricated with E-PEDOT:ClO4 have a slightly increased PV performance.

Facile Optimization of Thermoelectric Properties in PEDOT:PSS Thin Films through Acido-Base and Redox Dedoping Using Readily Available Salts

Poly(ethylene dioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) has emerged as a promising candidate for renewable, clean, and reliable energy generation from waste heat due to its thermoelectric properties. This largely stems from its tunable and potentially high electrical conductivity. However, the resulting small Seebeck coefficients diminish the thermoelectric efficiency. We employ dedoping methods making use of acido-base and redox dedoping in order to optimize its properties. In order to tune the charge carrier concentration in PEDOT:PSS thin films, aqueous solutions of readily available inorganic salts, namely, sodium hydrogen carbonate (NaHCO3), sodium sulfite (Na2SO3), and sodium borohydride (NaBH4), are introduced in different concentrations into PEDOT:PSS solutions before thin film fabrication. This yields optimized thermoelectric properties in terms of power factors up to 100 μW/K2 m. Changes in the electronic structure are characterized using UV–vis spectroscopy and XPS, while changes in th...

All-solid-state flexible supercapacitor based on spray-printed polyester/PEDOT:PSS electrodes

ABSTRACTWe report on a one-step spray printing technique to fabricate large-area flexible electrodes using poly (3, 4-ethylene dioxythiophene)-polystyrene sulfonate (PEDOT:PSS) and polyester cloth. The H3PO4 treated PEDOT:PSS electrodes exhibit an enhanced capacitance, high rate capability and wide voltage window (0–1.6 V). The printed polyester/PEDOT:PSS electrode treated with H3PO4 exhibits a specific capacitance of ∼40 F g−1 at 40 mV s−1. A large area device exhibits a high iR drop of 0.23 V, which can be minimized using conducting materials such as carbon cloth or steel mesh in place of polyester cloth.

Inexpensive Synthesis of Poly(Ethylenedioxythiophene‐Sulfobetaine) Films with High Bio‐Antifouling Ability

To prevent nonspecific interactions with biomolecules (e.g., proteins), blood cells, and microorganisms (e.g., bacteria, viruses, fungi, parasites) that can exert severe side effects, several bio‐inspired antifouling materials, including poly(ethylene glycol) and zwitterionic phosphocholine, sulfobetaine (SB), and carboxybetaine derivatives have been applied in biomedical electronic devices. In this paper, we report the development of an economical strategy for synthesizing ethylenedioxythiophene (EDOT)‐SB and creating the corresponding highly antifouling polymer films though electrochemical polymerization. The poly(EDOT‐SB) films inhibited 95% of the nonspecific binding of proteins from serum and prevented the adhesion of fibroblast cells. Moreover, the antifouling properties of the conducting film were maintained in both the oxidized and reduced states of PEDOT. Such zwitterionic, functionalized conducting polymer films appear to have great potential for application to bio‐electronic implant devices.

Versatile Fabrication Approach of Conductive Hydrogels via Copolymerization with Vinyl Monomers.

Functionalized poly(ethylene dioxythiophene) (f-PEDOT) was copolymerized with two vinyl monomers of different hydrophilicity, acrylic acid and hydroxyethyl methacrylate, to produce electroconductive hydrogels with a range of physical and electronic properties. These hydrogels not only possessed tailored physical properties, such as swelling ratios and mechanical properties, but also displayed electroactivity dependent on the chemical composition of the network. Raman spectroscopy indicated that the functional PEDOT in the hydrogels is in an oxidized form, most likely accounting for the good electrochemical response of the hydrogels observed in physiological buffer. In vitro cell studies showed that cardiac cells respond differently when seeded on hydrogel substrates with different compositions. This study presents a facile approach for the fabrication of electroconductive hydrogels with a range of properties, paving the way for scaffolds that can meet the requirements of different electroresponsive tissues.

Atmospheric plasma oxidative polymerization of ethylene dioxythiophene (EDOT) for the large‐scale preparation of highly transparent conducting thin films

A simple and easily scalable approach toward the simultaneous synthesis and deposition of conducting plasma‐polymerized 3,4‐ethylenedioxythiophene (ppEDOT) coatings is reported. Our atmospheric‐pressure dielectric barrier discharge (AP‐DBD) approach, operating at room‐temperature and atmospheric‐pressure, does not involve the use of oxidants other than the reactive oxygen species (ROS) formed by the open air Ar/O2 dielectric barrier discharge. The oxidative polymerization of EDOT is confirmed using UV‐visible (UV‐vis), Raman, and Fourier‐transform infrared (FTIR) spectroscopy. High‐resolution mass spectrometry (HRMS) investigations highlight the discrepancies between the synthesized ppEDOT and conventional PEDOT. Finally, highly transparent (i.e., 98% transmittance) and durable conducting thin films are deposited on polyethylene naphthalate (PEN) foils.

Synthesis and characterization of transparent conducting SWCNT/PEDOT: PSS composite films by spin coating technique

Transparent conducting carbon nanotube (CNT)/Poly (3,4 ethylenedioxy thiophene) poly(4-styrenesulfonate) (PEDOT:PSS) composite films are prepared by spin coating technique. The loading rate of CNTs in the host polymer is optimised to enhance the conductivity of the polymer without compromising the transparency of PEDOT:PSS. The effect of single walled CNT (SWCNT) loading on the transparency and conductivity are systematically studied using UV–vis-NIR Spectrophotometry and Hall Measurement. The structural features of the polymer are found to be unaffected by the incorporation of CNTs through XRD, FTIR and Raman analysis. The SWCNT form a network with the PEDOT:PSS matrix which enhances the conductivity of host. A six fold increase in the electrical conductivity of PEDOT:PSS is observed upon incorporation of 0.35wt% of SWCNT when the figure of merit of the transparent conductor is reduced by 102.

The feasibility of using solution-processed aqueous La2O3 as effective hole injection layer in organic light-emitting diode

Low-cost and scalable manufacturing boosts organic electronic devices with all solution process. La2O3 powders and corresponding aqueous solutions are facilely synthesized. Atomic force microscopy and scanning electron microscopy measurements show that solution-processed La2O3 behaves superior film morphology. X-ray diffraction and X-ray photoelectron spectroscopy measurements verify crystal phase and typical La signals. In comparison with the most widely-used hole injection layers (HILs) of MoOx and poly(ethylene dioxythiophene):poly(styrene sulfonate) (PEDOT:PSS), enhanced luminous efficiency is observed in organic light-emitting diode (OLED) using solution-processed La2O3 HIL. Current-voltage, impedance-voltage and phase angle-voltage transition curves clarify that solution-processed La2O3 behaves nearly comparable hole injection capacity to MoOx and PEDOT:PSS, and favorably tailors carrier balance. Moreover, the hole injection mechanism of solution-processed La2O3 is proven to be predominantly controlled by Fowler-Nordheim tunneling process and the hole injection barrier height between ITO and NPB via La2O3 interlayer is estimated to be 0.098 eV. Our experiments provide a feasible application of La2O3 in organic electronic devices with solution process.

Toward High Thermoelectric Performance of Thiophene and Ethylenedioxythiophene (EDOT) Molecular Wires

AbstractThe design of thermoelectric materials for the efficient conversion of waste heat into electricity requires simultaneous tuning of their electrical and thermal conductance. A comparative theoretical study of electron and phonon transport in thiophene and ethylenedioxythiophene (EDOT) based molecular wires is performed. It is shown that modifying thiophene by substituting ethylenedioxy enhances the thermoelectric figure of merit ZT for molecules of the same length. Furthermore, it is demonstrated that the electrical conductance of EDOT‐based wires decays more slowly with length than that of thiophene‐based wires and that their thermal conductance is lower. The room‐temperature ZT of undoped EDOT is found to be rather low. However, doping of EDOT by the electron acceptor tolunenesulfunate increases the Seebeck coefficient and electrical conductance, while decreasing the thermal conductance, leading to a thermoelectric figure of merit as high as ZT = 2.4.

The role of donor polymer and PEDOT:PSS formulation on adhesion processes in inverted organic solar cells

Organic photovoltaic devices (OPVs) are one of the most promising applications of organic semiconductors due to their compatibility with flexible plastic substrates resulting in lightweight, inexpensive, ergonomic and aesthetic products. While the electrical failure mechanisms in OPVs have been thoroughly investigated, little is known about their mechanical stability, which is as important and critical to ensure long term reliability. The characteristic thin films stresses of each layer present in organic solar cells, in combination with other possible fabrication, handling and operational stresses, provide the mechanical driving force for delamination of weak interfaces or even their decohesion, leading to a loss of device integrity and performance. In this study, we developed a technique to probe weak layers or interfaces in inverted polymer:PC60BM solar cells, establishing a new set-up for the so-called probe tack making it similar to a pull-off test. With this in hand, the adhesion of a variety of active layers towards a standard water-based poly(ethylene dioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) formulation was compared against that of a new organic-solvent based PEDOT:PSS. The organic-solvent based PEDOT:PSS formulation showed improved adhesion compared to the standard water-based formulation. Chemical characterization of the exposed surfaces indicated a difference in their composition, suggesting a stronger interaction of the organic-solvent based PEDOT:PSS with the active layer and resulting in a different fracture path. Indeed, all OPVs with water-based PEDOT:PSS showed a delamination localized at the active layer/PEDOT:PSS interface, while those with the organic-solvent formulation were not fractured at this interface but rather, in the active layer.

Ion Transport in Polymer Composites with Non-Uniform Distributions of Electronic Conductors

Ionic resistance is often a rate limiting factor in electrochemical systems such as batteries, supercapacitors, and ionic polymer actuators. Such cells typically contain laminated and interpenetrated structures consisting of one or two electronically conductive layers and an ionically conductive separator layer. Here we analyze the role of electrodes in determining ionic resistance, and study the effects of interpenetrating ionic and electronically conducting phases. We also show that conducting polymer electrodes that are polymerized on separator layers, as have been applied to create actuators, supercapacitors and electrochromic device, can be widely and unevenly distributed through the device. Swept sine and DC measurements are used with a four-point diffusion cell probe to characterize the phase dependent ionic impedances in 1. polypyrrole (PPy) coated polyvinylidene fluoride (PVDF) and 2. poly(ethylene dioxythiophene) (PEDOT) interpenetrated poly(ethylene oxide) (PEO) − nitrile butadiene rubber (NBR) co-polymer with various PEDOT content levels. A finite Warburg-based model is introduced to explain the frequency dependence, enabling a time constant for ion transport within membrane to be estimated. It is found that the separator layers in the composite membranes are shorted at higher frequencies (10∼100Hz). This effect is likely due to interpenetration of the electronic phases into the bulk of the separator layers, providing a means of reducing internal resistance and increase power at short times. Finally, a non-uniform impedance distribution model is introduced to predict the effective composite ionic conductivity in terms of the ionic conductivities of each phase, and their non-uniform volume fractions. Taken together, the approaches presented provide a means of probing the influence of ionic conductivities of various phases on the rate of charging in electrochemical devices.

Carbazole-based π-conjugated polyazomethines: Effects of catenation and comonomer insertion on optoelectronic features

A series of carbazole-based polyazomethines have been synthesized under micro-wave irradiation and without transition-metal based catalyst. The impact of both the catenation brought by the carbazole subunits and the insertion of a co-monomer, i.e. 3,4 ethylene dioxythiophene (EDOT), on the optical and electrochemical properties have been studied. Among the different polyazomethines synthesized, the best in terms of optical and electrochemical properties has been found to be the one with the azomethine function linked in positions 2,7 of carbazole subunits. Upon the insertion of the EDOT comonomer, an increase of the molecular weight and a red-shift in the absorption spectra has been observed, corresponding to a diminution of the electronic gap.

Influence of thermocleavable functionality on organic field-effect transistor performance of small molecules

Diketopyrrolopyrrole based donor-acceptor-donor conjugated small molecules using ethylene dioxythiophene as a donor was synthesized. Electron deficient diketopyrrolopyrrole unit was substituted with thermocleavable (tert-butyl acetate) side chains. The thermal treatment of the molecules at 160°C eliminated the tert-butyl ester group results in the formation of corresponding acid. Optical and theoretical studies revealed that the molecules adopted a change in molecular arrangement after thermolysis. The conjugated small molecules possessed p-channel charge transport characteristics in organic field effect transistors. The charge carrier mobility was increased after thermolysis of tert-butyl ester group to 5.07×10−5cm2/Vs.