• Proceedings of the Korean Fiber Society Conference
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• 2003.10b
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• pp.169-170
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• 2003

There was little development in transparent conductive polymer films and their limited studies have been mainly focused on polymer films coated by water-soluble PEDOT doped with the polymeric counteranion poly(4-styrenesulfonate) (PEDOT-PSS)[1-3]. However PEDOT-PSS as coating material has some difficulties because of high viscosity and low solubility in organic solvent except for in water. In this study, in order to extend practical applications of PEDOT and to prepare conductive PC films, we tried to prepare PEDOT-coated PC films and investigated their conductivity and thermal stability. (omitted)

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2011.05a
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• pp.106-107
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• 2011

Organic Light Emitting Diode(OLED), Optical Photovotaic Device(OPV)와 같은 유기소자에서 전극으로 적용되어지고 있는 Indium Tin Oxide (ITO) 박막의 유연성을 향상시키기 위하여 중간층으로 투명도(~80%)와 전도도(~1000 S/cm)가 우수한 PEDOT:PSS(PH1000)을 적용하였다. PEDOT:PSS(PH1000)의 적용으로 인하여 ITO 박막의 유연성이 현저히 개선됨과 동시에 PEDOT:PSS(PH1000)의 우수한 전도도로 인하여 보다 얇은 ITO의 두께에서도 우수한 면 저항(25 ${\Omega}/{\square}$ ~ 220 ${\Omega}/{\square}$) 및 비저항(3.75E-4 ${\Omega}{\cdot}cm$ ~ 4.40E-4 ${\Omega}{\cdot}cm$)의 값을 측정하였다.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.02a
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• pp.321-321
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• 2010

The PEDOT:PSS layer is usually used as hole transporting layer for the polymer bulk heterojunction solar cells. However, the interface between ITO and PEDOT:PSS is not stable and the chemical reaction between ITO and PEDOT can result in degraded device performance. We used the tungsten oxides as a hole transport layer by spin-coating. The $WO_3$ nanoparticles were well dispersed in ammonium hydroxide and deionized water and formed thin layer on the ITO anode. We found that $WO_3$ surface is more hydrophobic than the bare ITO or PEDOT:PSS-coated surfaces. The hydrophobic surfaces promote an ordered growth of P3HT films. A higher degree of P3HT ordering is expected to improve the hole mobility and the lifetime of the device using the tungsten oxide showed better stability compared to the device using the PEDOT:PSS.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.24 no.1
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• pp.49-55
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• 2015

This paper reports solution-processed, high-efficiency organic light-emitting diodes (OLEDs) fabricated by a knife coating method under ambient air conditions. In addition, indium tin oxide (ITO), traditionally used as the anode, was substituted by optimizing the conductivity enhancement treatment of poly(3,4-ethylene dioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) films on a polyethylene terephthalate (PET) substrate. The transmittance and sheet resistance of the optimized PEDOT:PSS anode were 83.4% and $27.8{\Omega}/sq$., respectively. The root mean square surface roughness of the PEDOT:PSS anode, measured by atomic force microscopy, was only 2.95 nm. The optimized OLED device showed a maximum current efficiency and maximum luminous density of 5.44 cd/A and $8,356cd/m^2$, respectively. As a result, the OLEDs created using the PEDOT:PSS anode possessed highly comparable characteristics to those created using ITO anodes.

• Applied Chemistry for Engineering
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• v.27 no.4
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• pp.402-406
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• 2016

In order to investigate the thermal stability of electro-conductive poly(3,4-ethylenedioxythiophene)-poly(styrene sulfonate) (PEDOT/PSS), we have prepared films by casting PEDOT/PSS aqueous solution without using a binding material and measured surface resistances of the films while annealing at $200^{\circ}C$. Electrical properties of films were improved by annealing, and the maximum conductivity ($540S{\cdot}m^{-1}$) after annealing for 2 hrs was found to be approximately 3 times higher than that ($180S{\cdot}m^{-1}$) of the original film. The conductivities, however, dramatically decreased with an increase in annealing time and dissipated after 24 hrs of annealing. On the other hand, PEDOT/PSS films hybridized with graphene oxide (GO) displayed a salient improvement in conductivity by annealing, which was measured to be around $600S{\cdot}m^{-1}$ even after 30 hrs of annealing at $200^{\circ}C$. We tentatively conclude that hybridization with GO enhances the thermal stability of PEDOT/PSS.

• Journal of Sensor Science and Technology
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• v.27 no.3
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• pp.186-191
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• 2018

Smart textile industries have been precipitously developed and extended to electronic textiles and wearable devices in recent years. In particular, owing to an increasingly aging society, the elderly healthcare field has been highlighted in the smart device industries, and pressure sensors can be utilized in various elderly healthcare products such as flooring, mattress, and vital-sign measuring devices. Furthermore, elderly healthcare products need to be more lightweight and flexible. To fulfill those needs, textile-based pressure sensors is considered to be an attractive solution. In this research, to apply a textile to the second layer using a pressure sensing device, a novel type of conductive textile was fabricated using vapor phase polymerization of poly(3,4-ethylenedioxythiophene) (PEDOT). Vapor phase polymerization is suitable for preparing the conductive textile because the reaction can be controlled simply under various conditions and does not need high-temperature processing. The morphology of the obtained PEDOT-conductive textile was observed through the Field Emission Scanning Electron Microscope (FESEM). Moreover, the resistance was measured using an ohmmeter and was confirmed to be adjustable to various resistance ranges depending on the concentration of the oxidant solution and polymerization conditions. A 3-layer 81-point multi-pressure sensor was fabricated using the PEDOT-conductive textile prepared herein. A 3D-viewer program was developed to evaluate the sensitivity and multi-pressure recognition of the textile-based multi-pressure sensor. Finally, we confirmed the possibility that PEDOT-conductive textiles could be utilized by pressure sensors.

• Elastomers and Composites
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• v.46 no.4
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• pp.290-294
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• 2011

The surface resistance of poly(3,4-ethylenedioxythiophene)-polystyrene sulfonate (PEDOT/PSS), which has appeared to be one of the most successful conductive polymers, is affected by the solvent. In this paper, pellet-type PEDOT/PSS was suspended in $H_2O$, ethanol (EtOH), ethylene glycol (EG) or dimethylsulfoxide (DMSO), and coated on PET film. The surface resistances of the films made from EG or DMSO suspension were observed to be lower, nearly by 2 orders of magnitude, than that made from $H_2O$ suspension. No significant difference among four kinds of films was observed when the thermal properties and chemical structures were investigated by TGA and XPS, respectively. However, particle size of PEDOT/PSS was in the range of $1-3{\mu}m$ in EG or DMSO, on the other hand, less than $0.1{\mu}m$ in $H_2O$. It is considered that the particle size of PEDOT/PSS in the suspension plays an important role for the surface resistance.

• Journal of Sensor Science and Technology
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• v.24 no.1
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• pp.22-28
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• 2015

This study demonstrates a polyimide nerve cuff electrode with a conductive polymer for improving recording signal quality at peripheral nerve. The nerve cuff electrodes with platinum (Pt), iridium oxide (IrOx), and poly(3,4-ethylenedioxythiophene): p-toluene sulfonate (PEDOT:pTS) were fabricated and investigated their electrical characteristics for improving recorded nerve signal quality. The fabricated nerve cuff electrodes with Pt, IrOx, and PEDOT:pTS were characterized their impedance and CDC by using electrochemical impedance spectroscopy (EIS) and cyclic voltammetry. The impedance of PEDOT:pTS measured at 1 kHz was $257{\Omega}$, which was extremely lower than the value of the nerve cuff electrodes with IrOx ($15897{\Omega}$) and Pt ($952{\Omega}$), respectively. Furthermore, the charge delivery capacity (CDC) of the nerve cuff electrode with PEDOT:pTS was dramatically increased to 62 times than the nerve cuff electrode with IrOx. In ex-vivo test using extracted sciatic nerve of spaque-dawley rat (SD rat), the PEDOT:pTS group exhibited higher signal-to-interference ratio than IrOx group. These results indicated that the nerve cuff electrode with PEDOT:pTS is promising for effective implantable nerve signal recording.

• Journal of the Korean Electrochemical Society
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• v.24 no.4
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• pp.93-99
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• 2021

In order to decrease the weight of stretchable energy storage devices, interest in developing lightweight materials to replace metal current collectors is increasing. In this study, nanofibers prepared by electrospinning a conductive polymer, PEDOT:PSS, were used as current collectors for lithium ion batteries. The nanofiber showed improved electrical conductivity by using DMSO, a dopant, and indicated a stretch rate of 30% or more from the elasticity evaluation result. In addition, the use of the nanofiber current collector facilitates penetration of the liquid electrolyte and exhibits the effect of increasing the electronic conductivity through the nanofiber network. The lithium-ion battery using the DMSO-doped PEDOT:PSS@PAM nanofiber current collector indicated a high discharge capacity of 135mAh g^-1, and indicated a high capacity retention rate of 73.5% after 1000 cycles. Thus, the excellent electrochemical stability and mechanical properties of conductive nanofibers showed that they can be used as lightweight current collectors for stretchable energy storage devices.

• Korean Journal of Materials Research
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• v.18 no.9
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• pp.503-506
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• 2008

The effect of silver nanoparticles (NPs) incorporation on the electronic properties of poly (3, 4-ethylenedioxythiphene) : poly(styrenesulfonate) (PEDOT : PSS) films was investigated. The surface of silver NPs was stabilized with trisodium citrate to control the size of silver NPs and prevent their aggregation. We obtained ca. 5 nm sized silver NPs and dispersed NPs in PEDOT : PSS solution. Sheet resistance, surface morphology, bonding state, and work function values of the PEDOT : PSS films were modified by silver NPs incorporation as well as annealing temperature. Sodium in silver NPs solution could lead to a decrease of work function of PEDOT : PSS; however, large content of silver NPs have an effect on the increase in work function, resulting from charge localization on the silver NPs and a decrease in the number of charge-trapping-related defects by chemical bond formation.