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Electrochemical Switching in Conducting Polymers – Printing Paper Electronics
Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
2008 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

During the last 30 years a new research and technology field of organic electronic materials has grown thanks to a groundbreaking discovery made during the late 70’s. This new field is today a worldwide research effort focusing on exploring a new class of materials that also enable many new areas of electronics applications. The reason behind the success of organic electronics is the flexibility to develop materials with new functionalities via clever chemical design and the possibility to use low‐cost production techniques to manufacture devices.

This thesis reports different aspects of electrochemical applications of organic electronics. We have shown that the color contrast in reflective and transmissive electrochromic displays can be almost doubled by adding an extra electrochromic polymer. The choice of electrochromic material was found to be limited by its electrochemical over‐oxidation (ECO) properties, which is one of the main degradation mechanisms found in displays. The irreversible and non‐conducting nature of over‐oxidized films encouraged us to use it in a novel patterning process in which polythiophene films can be patterned through local and controlled deactivation of the conductivity. ECO can be combined with various patterning tools such as screen printing for low‐cost roll‐to‐roll manufacturing or photolithography, which enables patterning of small features. Studies have shown that electronic conductivity contrasts beyond 107 can be achieved, which is enough for various simple electronic systems. To generate better understanding of the ECO phenomenon, the effect of pH on the over‐oxidation characteristics was studied. The results suggest that a part of the mechanism for over‐oxidation depends on the OH– concentration of the electrolyte used. Over‐oxidation has also been used in electrochemical loggers, where the temperature and time dependence of the propagation of an over‐oxidation front is used to monitor and record the temperature of a package.

Abstract [sv]

Dagligen kommer vi i kontakt med olika plastmaterial. Dessa har vanligtvis mycket dålig elektrisk ledningsförmåga och används oftast som isolerande material. Det finns dock en klass av plaster som är halvledande eller ledande. Sedan upptäckten av dessa material för mer än 30 år sedan har nya material och användningsområden utvecklats och nu börjar de första produkterna baserad på organisk elektronik komma ut på marknaden. En stor fördel med de ledande plasterna är att egenskaperna kan anpassas genom att ändra den kemiska strukturen. Man kan dessutom lösa upp dem och skapa ledande bläck, som sedan kan användas i vanliga tryckmaskiner. Detta gör det möjligt att på ett enkelt och billigt sätt tillverka elektronik på liknande sätt som till exempel tidningar trycks idag.

Den här avhandlingen behandlar en del av det nya området som berör elektrokemiska komponenter och några av dess tillämpningar. Fokus ligger främst på billig, tryckt elektronik. Bland annat presenteras ett sätt att fördubbla kontrasten för tryckta pappersdisplayer, ett nytt sätt att mönstra ledande plaster och elektrokemisk temperaturloggningsetikett som kan övervaka temperaturen för förpackningar under transport. Den mekanism som förstör ledningsförmågan vid höga spänningar har varit ett återkommande inslag i de studier som har genomförts här. Denna mekanism förstör komponenterna under drift men kan också användas för att ta bort ledningsförmågan som mönstringsmetod eller för att lagra information, permanent, i temperaturloggningsetiketten.

Place, publisher, year, edition, pages
Linköping: Linköping University Electronic Press , 2008. , 37 p.
Series
Linköping Studies in Science and Technology. Dissertations, ISSN 0345-7524 ; 1212
National Category
Inorganic Chemistry
Identifiers
URN: urn:nbn:se:liu:diva-15132ISBN: 9789173938013 (print)OAI: oai:DiVA.org:liu-15132DiVA: diva2:54538
Public defence
2008-10-10, K3, Kåkenhus, Campus Norrköping, Linköpings universitet, Linköping, 10:15 (English)
Opponent
Supervisors
Available from: 2008-10-17 Created: 2008-10-17 Last updated: 2017-12-14Bibliographically approved
List of papers
1. Patterning polythiophene films using electrochemical over-oxidation
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2005 (English)In: Smart materials and structures (Print), ISSN 0964-1726, E-ISSN 1361-665X, Vol. 14, N21-N25 p.Article in journal (Refereed) Published
Abstract [en]

Over-oxidative degradation of polythiophenes, which breaks the conjugation and destroys the electronic conductivity of the polymer, is well documented as a liability in these materials. We use this 'weakness', via controlled electrochemical over-oxidation, in a novel subtractive patterning technique compatible with high-speed reel-to-reel printing technology. We demonstrate the use of electrochemical over-oxidation to pattern PEDOT:PSS films via an x–y plotter, silk-screen and high-resolution photolithographic techniques, resulting in patterning down to a resolution of 2 µm and a conduction contrast between unpatterned and patterned areas of up to 108.

Place, publisher, year, edition, pages
IOP Elctronic Journals, 2005
Keyword
Not Available.
National Category
Inorganic Chemistry
Identifiers
urn:nbn:se:liu:diva-14024 (URN)10.1088/0964-1726/14/4/N03 (DOI)
Available from: 2008-11-12 Created: 2008-10-17 Last updated: 2017-12-13Bibliographically approved
2. The effect of pH on the elechtrochemical over-oxidation of PEDOT:PSS films
Open this publication in new window or tab >>The effect of pH on the elechtrochemical over-oxidation of PEDOT:PSS films
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2007 (English)In: Solid State Ionics, ISSN 0167-2738, E-ISSN 1872-7689, Vol. 177, no 39-40, 3521-3527 p.Article in journal (Refereed) Published
Abstract [en]

Chemical degradation of conjugated polymers is one cause of material failures in polymer-based (opto)electronic devices, but can also be used as a technique for subtractive patterning of polymer films. When a large anodic potential is applied to the conducting polymer blend poly(3,4-ethylenedioxythiophene)-poly(4styrenesulfonate), PEDOT:PSS, an over-oxidation reaction occurs, altering its electrical conductivity. Here, we have studied the effect of pH on the electrochemical over-oxidation process of PEDOT in PEDOT:PSS. High pH is associated with a decrease of over-oxidation potential and an increase of resistivity in the resulting film. Vibrational spectroscopy and photoelectron spectroscopy measurements on over-oxidized PEDOT:PSS films indicate that the decrease in conductivity results from cleavage of the conjugation pathway accompanied by the formation of sulfone, carbonyl and carboxylic groups in the polymer chain.

Place, publisher, year, edition, pages
ScienceDirect, 2007
Keyword
Poly(3, 4-ethylenedioxythiophene), Degradation, Over-oxidation, XPS, FTIR, Conjugated polymer, Polythiophenes
National Category
Inorganic Chemistry
Identifiers
urn:nbn:se:liu:diva-14026 (URN)10.1016/j.ssi.2006.10.008 (DOI)
Available from: 2008-11-12 Created: 2008-10-17 Last updated: 2017-12-13Bibliographically approved
3. Evaluation of active materials designed for use in printable electrochromic polymer displays
Open this publication in new window or tab >>Evaluation of active materials designed for use in printable electrochromic polymer displays
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2006 (English)In: Thin Solid Films, ISSN 0040-6090, E-ISSN 1879-2731, Vol. 515, no 4, 2485-2492 p.Article in journal (Refereed) Published
Abstract [en]

In a step towards roll-to-roll production of polymer-based electrochromic displays on flexible substrates, nine thiophene-based polymers and copolymers designed to increase the contrast of displays based on poly(3,4-ethylenedioxythiophene)/poly(styrene-sulfonic acid) have been synthesized and evaluated with respect to their absorbance (contrast), switch speed, and ability to switch reversibly in a water-based electrolyte. The results of the evaluation, including cyclic voltammetry and optically visible absorption, provide a basis for understanding what an aqueous electrolyte electrochromic display requires in terms of oxidation potential and material stability, and the effect of chemical structure on the reversibility and speed of switching. © 2006 Elsevier B.V. All rights reserved.

Keyword
Electrochromic display; Conjugated polymers; Poly(3, 4-ethylenedioxythiophene)
National Category
Engineering and Technology
Identifiers
urn:nbn:se:liu:diva-37443 (URN)10.1016/j.tsf.2006.07.149 (DOI)35830 (Local ID)35830 (Archive number)35830 (OAI)
Available from: 2009-10-10 Created: 2009-10-10 Last updated: 2017-12-13
4. Improving the contrast of all-printed electrochromic polymer on paper displays
Open this publication in new window or tab >>Improving the contrast of all-printed electrochromic polymer on paper displays
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2009 (English)In: JOURNAL OF MATERIALS CHEMISTRY, ISSN 0959-9428 , Vol. 19, no 13, 1799-1802 p.Article in journal (Refereed) Published
Abstract [en]

PEDOT:PSS-based electrochromic displays have been explored for manufacture on flexible paper substrates in roll-to-roll printing presses at high volumes and low costs. Here, we report the improvement of the optical contrast of such devices by adding an extra layer of a dihexyl-substituted poly(3,4-propylenedioxythiophene) (PProDOT-Hx2) to complement the optical absorption spectrum of PEDOT: PSS. The oxidized state of PProDOT-Hx2 is highly transparent and is an intense magenta color while in the reduced state. By adding a layer of PProDOT-Hx2 directly on top of PEDOT: PSS, we were able to improve the optical contrast by nearly a factor of two. In this report, we present optical and electrochemical data of PProDOT-Hx2/PEDOT: PSS-based electrochromic paper displays and compare their performance with PEDOT: PSS-only equivalents.

National Category
Engineering and Technology
Identifiers
urn:nbn:se:liu:diva-17504 (URN)10.1039/b820677e (DOI)
Available from: 2009-03-27 Created: 2009-03-27 Last updated: 2017-02-03
5. Printable organic temperature logger based on overoxidation front propagation in PEDOT:PSS
Open this publication in new window or tab >>Printable organic temperature logger based on overoxidation front propagation in PEDOT:PSS
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(English)Manuscript (Other academic)
Abstract [en]

An electrochemical temperature logger has been realized by using the propagation of overoxidation fronts in stripes of poly(3,4-ethylenedioxythiopehene) blended with poly(styrenesulfonate) (PEDOT:PSS). The over-oxidation front propagation has been characterized and related to the ionic conductivity of polyethylene glycol (PEG) electrolytes. The electrolytes were chosen to have a phase transition in the temperature interval to be monitored, resulting in large conductivity variations and thereby an easily interpreted output. A logger demonstrator has been fabricated and shown to detect a temperature increase and a following temperature decrease. This very simple device is cheap to produce and could be used to monitor the temperature of packages.

Keyword
Not available.
National Category
Inorganic Chemistry
Identifiers
urn:nbn:se:liu:diva-15129 (URN)
Available from: 2008-11-12 Created: 2008-10-17 Last updated: 2017-02-03Bibliographically approved

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Tehrani, Payman

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