Papers by Keyword: PEDOT/PSS

Abstract: We report on optimization of bar coating method for preparation of PEDOT/PSS thin films with large area on poly (ethylene terephthalate) (PET) substrates, by investigating various coating parameters in terms of sheet resistance (R_s) and transparency (T). As a result, we have found that the addition of 1 wt% Capstone FS-30, 7 wt% ethylene glycol (EG), and a motor rotation speed of 100.8 rpm, as well as a heat temperature of 120 °C is the optimum coating condition to obtain high-performance PEDOT/PSS thin films with large area whose sheet resistance (R_s) and transmittance at 550 nm (T) were 230 Ω sq^-1 and 84%,respectively.

Abstract: This research project produced two fabricated ultrafine conductive polymeric fibers. The first fiber was fabricated from a polymer and conductive polymer solution, and the second was fabricated from a polymer and metal nanoparticle/ nanocomposite. The resulting fibers were characterized and analyzed. For all fiber samples, the ultrafine polymeric fibers were fabricated using polyvinyl alcohol (PVA). The conductive polymer used in the first fiber sample was poly (3,4-ethylenedioxythiophene)/ polystyrene sulfonate (PEDOT/PSS). The conductive nanoparticles used in the second fiber sample were silver nanoparticles (AgNPs). The ultrafine conductive polymer fibers and the ultrafine conductive nanoparticle fibers were fabricated using an electrospining process. During the fabrication process of each fiber sample, different concentrations of either PEDOT/PSS, for fiber sample one, or AgNPs, for fiber sample two, were combined in PVA solution. Using optimal conditions, ultrafine fibers were fabricated at intervals of 5 min for the creation of random fibers, and intervals of 20 min for the creation of aligned fiber mats. The resulting fibers ranged from 0.1 μm to 0.2 μm in diameter. After characterization and analysis of the conductive ultrafine polymeric fibers, using either the PVA:PEDOT/PSS compound or the PVA:AgNPs compound, both samples produced greater conductive capacities with greater concentrations of solution. For the random fiber samples, the conductive capacity was sporadic. However, the ultrafine fiber mats (PVA:AgNPs) supported a capacity from 3.64 S/cm to 10.64 S/cm, and the PVA:PEDOT/PSS ultrafine fiber mats supported a capacity from 4.49 S/cm to 7.08 S/cm.

Abstract: Poly (vinyl alcohol)-silver nanoparticles (PVA:AgNPs), and poly (vinyl alcohol)-silver nanoparticles-poly (3, 4-ethylene dioxythiophene)/poly (styrene sulfonate) (PVA:AgNPs: PEDOT/ PSS) were generated as ultra-fine electrospun fibers using the aligned fiber mat and aligned single fiber techniques. SEM and TEM were used to confirm the morphology, diameter size, and fiber alignment of the ultra-fine fibers. A two-probe technique was utilized to assess the electrical conductivity of the ultrafine fibers. The highest conductivity of PVA:AgNPs, (10 %w/v:0.75 %w/v) with a fiber diameter of 0.152 μm, with voltage applied at 17.5 kV within a 20 min collection period in the electrospinning process, was 43.20 S/cm; whereas the highest conductivity of PVA:AgNPs: PEDOT/PSS, (10 %w/v:0.25 %w/v:0.084 %w/v), with a fiber diameter of 0.158 μm and voltage applied at 17.5 kV within a 45 min collection period in the electrospinning process, was 92.18 S/cm.

Abstract: Free-standing films made of poly(3,4-ethylenedioxythiophene) doped with poly(4-styrenesulfonate) (PEDOT/PSS) were prepared by casting water dispersion of its colloidal particles. Specific surface area, water vapor sorption, and electro-active polymer actuating behavior of the resulting films were investigated by means of sorption isotherm, and electromechanical analysis. It was found that the non-porous PEDOT/PSS film, having a specific surface area of 0.13 m2/g, sorbed water vapor of 1080 cm3(STP)/g, corresponding to 87 wt%, at relative water vapor pressure of 0.95. A temperature rise from 25 to 40 °C lowered sorption degree, indicative of an exothermic process, where isosteric heat of sorption decreased with increasing water vapor sorption and the value reached 43.9 kJ/mol, being consistent with the heat of water condensation (44 kJ/mol). Upon application of 10 V, the film underwent contraction of 2.4% in air at 50% relative humidity (RH) which significantly increased to 4.5% at 90% RH. The principle lay in desorption of water vapor sorbed in the film due to Joule heating, where electric field was capable of controlling the equilibrium of water vapor sorption.

Abstract: An epoxy paint containing PEDOT/PSS was described herein. The corrosion behavior of steel samples coated with the paint was investigated in seawater. For this purpose, electrochemical impedance spectroscopy was utilized and surface morphology of coatings after corrosion was observed using scanning electron microscope. It was found that the addition of small PEDOT/PSS to the epoxy resin increased its corrosion protection efficiency. Meanwhile, the possible mechanism was discussed.

Abstract: We have fabricated a low-cost and flexible NH₃ gas sensor using thermal ink-jet printing. The poly (3,4-ethylene dioxythiophene) doped with polystyrene sulfonated acid (PEDOT/PSS) with thickness of ~ 2 μm was used as a sensing film. The interdigitated electrode using patterned aluminum plate was attached over the sensing film. Atomic force microscopy results show the high homogeneous film and only small roughness is presented on the sensing film. This sensor exhibits high selectivity and sensitivity to NH₃ at room temperature. The sensor response works linearly with gas concentrations between 100-1000 ppm. The modulation of conducting polymer/metal electrode interface plays a role in the sensing mechanism of NH₃. Changes in the position of interdigitated electrodes can change the dominant sensing mechanism of typical polymer gas sensor.

Abstract: The ionic materials were added to PEDOT/PSS solution as secondary dopants. The conductivity of PEDOT/PSS film improved with adding ionic materials. The film of PEDOT/PSS with 1% pyridinium p-toluene-sulfonate showed the conductivity of 23S/cm, which is increased about three orders than the film of origin PEDOT/PSS with 0.028S/cm. The surface morphology of films of PEDOT/PSS mixture is investigated by atomic force microscope. The AFM showed the increasing of grain size with the addition of pyridinium p-toluene-sulfonate.

Abstract: We have studied the effect of various electrodes on non-volatile polymer memory devices. The ITO/PEDOT:PSS/Top electrode (TE) devices had bipolar switching behavior. The OFF current level of devices increased from 3×10-4 A to 3×10-3 A and the ON voltage decreased from 0.8 V to 0.5 V as the TE work function increased. The yield of devices decreased from over 50 % to under 10 % as the TE work function of devices increased. This result occurred because carrier injection was affected by the TE work function.

Abstract: Conducting polyacrylonitrile (PAN) nanofiber mats were prepared by dipping non-woven nanofiber mats of PAN in the solution of poly(3,4-ethylenedioxythiophene)/poly(4-styrenesulfonate) (PEDOT/PSS). PAN nanofiber mats were fabricated via the electrospinning process. The solvent used for PEDOT/PSS was ethylene glycol and isopropanol. The morphology of the resulting PAN nanofibers and the coating layers was investigated using SEM analysis. The electrical conductivity of PEDOT/PSS coated PAN nanofiber mats was measured by the four-point probe method, for different concentrations of solvent in the PEDOT/PSS solution. An addition of ethylene glycol resulted in higher electrical conductivity of the coated mats than that of isopropanol. The resistive humidity sensing properties were also investigated. The device reproducibility was presented by vapor adsorption/desorption dynamic cycles. The reproducibility of the PEDOT/PSS coated mats was superior to that of neat PEDOT/PSS films. The response sensitivity of coated mats using isopropanol as solvent was higher than that using ethylene glycol.

Abstract: In recent years there have been vast efforts to establish organic electronic devices. A key property of such devices is the possibility to fabricate them on flexible substrates. As the layers are mechanically stressed during bending, the knowledge of mechanical properties of the materials used will become very important. In this research the mechanical properties of the intrinsically conductive and widely used polymer PEDOT/PSS were investigated using a micro tensile test setup. The tensile tests showed values for Young’s Modulus in the range from 1 GPa to 2.7 GPa, for the tensile strength in a range from 25 MPa to about 55 MPa and for the total strain at break between 3% and 5%, all of them depending on relative humidity.