Stability and degradation of conducting polymers in electrochemical systems

Pud, A. A.

doi:10.1016/0379-6779(94)90155-4

Cited by 201 publications

(120 citation statements)

References 96 publications

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“…PEDOT:PSS is well characterized, and polythiophenes are known to possess higher electrochemically stability than polypyrroles. [ 6,[28][29][30] In addition to the charge balancing function, the coating of PEDOT on top of the silver grid increased the conductivity in the hexagonal grid patterns. The conductive PEDOT:PSS coating homogenized the electrical fi eld such that the blooming effect was not observed and the devices switched evenly between the two redox states (compare Figure 1 A and 1 B).…”

Section: Dual Functionality Of Pedot:pssmentioning

confidence: 98%

“…These could be redox reactions of water due to moisture in the device or irreversible oxidation or reduction of the polymer fi lms. [6][7][8][9] Such reactions can lead to reduced optical contrast, increased response times, and ultimately render the ECD non-functional.One approach is using thin metal grids as electrode material. Such grids have been utilized as counter electrodes in inorganic based ECDs, and we have previously shown how ITO can be replaced by fl exoprinting a silver based conductive hexagonal grid onto a transparent polyethylene terephthalate (PET) substrate.…”

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Fast Switching ITO Free Electrochromic Devices

Jensen

Kim

et al. 2013

Adv Funct Materials

110

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Indium-doped tin oxide free electrochromic devices are prepared by coating electrochromic polymers onto polyethylene terephthalate substrates encompassing two different silver grids as electrodes. One design comprises a fl exoprinted highly conductive silver grid electrode, yielding electrochromic devices with a response time of 2 s for an optical contrast of 27%. The other design utilizes an embedded silver grid electrode whereupon response times of 0.5 s for a 30% optical contrast are realized when oxidizing the device. A commercially available conductive poly(3,4-ethylenedioxythiophene):poly(4-styrenesulfonate acid) formulation (PEDOT:PSS) is coated onto the silver grids as a charge balancing polymer, and is in this setting found to be superior to a polypyrrole previously employed in electrochromic devices. In addition, the PEDOT:PSS layer increases the conductivity in the hexagonal grid structure. DOI . IntroductionThe development of electrochromic devices (ECDs) has moved from laboratory conditions into pilot plants; whereby, new challenges have emerged that include avoidance of vacuum processing steps and use of simple printing, coating, and lamination methods for deposition and assembly of the devices. If these challenges are successfully addressed, polymer based electrochromic devices will be commercially attractive and competitive to existing solutions. A main obstacle is the replacement of indium-doped tin oxide (ITO) as the transparent electrode material. ITO has been widely used as electrode material in organic electronics, but due to the scarcity of indium, substituting this material for a less expensive one would signifi cantly reduce production costs of ECDs. [1][2][3] Another incitement to replace ITO is the vast amount of energy used in the sputtering process employed in the production of ITO covered substrates. By avoiding such energy consuming processes, one would be able to manufacture ECDs with limited energy consumption from materials, to manufacturing and operation.From an operational point of view, the use of ITO as electrode material in ECDs is problematic since a low concentration of charge carriers in ITO gives rise to a large sheet resistance. It has been established that the electrode resistance has a marked effect on the response time and optical contrast of an ECD, [ 4 ] and high electrode resistance leads to a non-uniform potential across the electrode (Ohmic loss), and a non-uniform current distribution in the electrolyte. [ 5 ] By using electrodes of moderate conductivity, increasing potentials are needed to achieve satisfactory response times and optical contrast, as the ionic mobility (already impeded by the semisolid gel electrolyte) partly depends on the electric fi eld between the two electrodes. Due to several other chemical components, increasing the potential confl icts with the voltage limits, outside of which side reactions are likely to occur. These could be redox reactions of water due to moisture in the device or irreversible oxidation or reduction of the polymer fi...

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Section: Dual Functionality Of Pedot:pssmentioning

confidence: 98%

mentioning

confidence: 99%

Fast Switching ITO Free Electrochromic Devices

Jensen

Kim

et al. 2013

Adv Funct Materials

110

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“…The mechanisms of anodic over-oxidation of CP are quite complex and remain controversial. However, according to Pud [18], these fall approximately into two categories: cross-linking and nucleophilic attack of the polymer chain. In Fig.…”

Section: Methodsmentioning

confidence: 99%

Activity and long-term stability of PEDOT as Pt catalyst support for the DMFC anode

2007

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The feasibility of using poly(3,4-ethylenedioxythiophene) (PEDOT) as Pt catalyst support for direct methanol fuel cell (DMFC) anodes was investigated. Measurements with freshly prepared Pt-PEDOT/C electrodes showed poor activity for methanol oxidation in a half-cell and a DMFC. A substantial enhancement in that activity was evident after either electrochemical over-oxidation of PEDOT or long-time storage of the Pt-PEDOT/C gas diffusion electrode (GDE) in air. Both procedures led to a reorganization and increase in porosity of the reaction layer, which obviously contributed to better methanol accessibility to Pt catalyst active centres. The effects of electrochemical activation and long-time storage in air on the morphology and elementary composition of the Pt-PEDOT layer were investigated by means of Hg porosimetry and SEM/EDAX. It was found that the increase in porosity was due to degradation of PEDOT characterized by a significant depletion of sulphur and oxygen in the conducting polymer matrix.

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“…Basic electrochemistry work on common conjugated polymers is often limited to a demonstration of quasi-reversibility and a deriviation of the highest occupied/lowest unoccupied molecular orbital (HOMO/LUMO) levels of a material. Further, over-oxidation, or a second oxidation reaction at a single doping site, [33] has been shown to limit a number of these applications. Overoxidized polymers tend to be highly reactive species that degrade heavily and lose mechanical stability.…”

Section: Basic Research Needsmentioning

confidence: 99%

Organic Electronics: The Ions Have It

Leger

2008

Advanced Materials

104

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Organic electronics research has focused primarily on flexible, inexpensive versions of traditional semiconductor technologies. Although mixed ionic/electronic conduction in conjugated organic materials introduces exciting functionality, the understanding of the fundamental processes that take place is still in its infancy. In this Research News article, the advantages, applications, and basic research needs that relate to the incorporation of ionic carriers in organic electronic materials and devices are discussed and placed in the broader context of the field.

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Stability and degradation of conducting polymers in electrochemical systems

Cited by 201 publications

References 96 publications

Fast Switching ITO Free Electrochromic Devices

Fast Switching ITO Free Electrochromic Devices

Activity and long-term stability of PEDOT as Pt catalyst support for the DMFC anode

Organic Electronics: The Ions Have It

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