| 1. |
- Andersson Ersman, Peter, et al.
(författare)
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Fast-switching all-printed organic electrochemical transistors
- 2013
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Ingår i: Organic electronics. - : Elsevier. - 1566-1199 .- 1878-5530. ; 14:5, s. 1276-1280
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Tidskriftsartikel (refereegranskat)abstract
- Symmetric and fast (∼5 ms) on-to-off and off-to-on drain current switching characteristics have been obtained in screen printed organic electrochemical transistors (OECTs) including PEDOT:PSS (poly(3,4-ethylenedioxythiophene) doped with poly(styrene sulfonic acid)) as the active transistor channel material. Improvement of the drain current switching characteristics is made possible by including a carbon conductor layer on top of PEDOT:PSS at the drain electrode that is in direct contact with both the channel and the electrolyte of the OECT. This carbon conductor layer suppresses the effects from a reduction front that is generated in these PEDOT:PSS-based OECTs. In the off-state of these devices this reduction front slowly migrate laterally into the PEDOT:PSS drain electrode, which make off-to-on switching slow. The OECT including carbon electrodes was manufactured using only standard printing process steps and may pave the way for fully integrated organic electronic systems that operate at low voltages for applications such as logic circuits, sensors and active matrix addressed displays.
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| 2. |
- Andersson Ersman, Peter, et al.
(författare)
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Printed passive matrix addressed electrochromic displays
- 2013
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Ingår i: Organic electronics. - : Elsevier BV. - 1566-1199 .- 1878-5530. ; 14:12, s. 3371-3378
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Tidskriftsartikel (refereegranskat)abstract
- Flexible displays are attracting considerable attention as a visual interface for applications such as in electronic papers paper electronics. Passive or active matrix addressing of individual pixels require display elements that include proper signal addressability, which is typically provided by non-linear device characteristics or by incorporating transistors into each pixel. Including such additional devices into each pixel element make manufacturing of flexible displays using adequate printing techniques very hard complicated. Here, we report all-printed passive matrix addressed electrochromic displays (PMAD), built up from a very robust three-layer architecture, which can be manufactured using standard printing tools. Poly(3,4-ethylenedioxythiophene) doped with poly(styrenesulfonate) (PEDOT:PSS) serves as the conducting electrochromic pixel electrodes carbon paste is used as the pixel counter electrodes. These electrodes sandwich self-assembled layers of a polyelectrolyte that are confined to desired pixel areas via surface energy patterning. The particular choice of materials results in a desired current vs. voltage threshold that enables addressability in electronic cross-point matrices. The resulting PMAD operates at less than 3 V, exhibits high colour switch contrast without cross-talk promises for high-volume low-cost production of flexible displays using reel-to-reel printing tools on paper or plastic foils.
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| 3. |
- Berggren, Magnus, et al.
(författare)
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Electrochromic Displays
- 2010
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Ingår i: Iontronic. - Boca Raton : CRC Press; Taylor & Francis Group. - 9781439806883 - 9781439806890 ; , s. 131-139
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- The field of organic electronics promises exciting new technologies based on inexpensive and mechanically flexible electronic devices. It has progressed over the past three decades to the point of commercial viability and is projected to grow to a 30 billion dollar market by the year 2015. Exploring new applications and device architectures, this book sets the tone for that exploration, gathering a community of experts in this area who are focused on the use of ionic functions to define the principle of operation in polymer devices. The contributors detail relevant technologies based on organic electronics, including polymer electrochromic devices and light-emitting electrochemical cells.
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| 4. |
- Blaudeck, Thomas, et al.
(författare)
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Simplified Large-Area Manufacturing of Organic Electrochemical Transistors Combining Printing and a Self-Aligning Laser Ablation Step
- 2012
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Ingår i: Advanced Functional Materials. - : Wiley-VCH Verlag Berlin. - 1616-301X .- 1616-3028. ; 22:14, s. 2939-2948
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Tidskriftsartikel (refereegranskat)abstract
- A hybrid manufacturing approach for organic electrochemical transistors (OECTs) on flexible substrates is reported. The technology is based on conventional and digital printing (screen and inkjet printing), laser processing, and post-press technologies. A careful selection of the conductive, dielectric, and semiconductor materials with respect to their optical properties enables a self-aligning pattern formation which results in a significant reduction of the usual registration problems during manufacturing. For the prototype OECTs, based on this technology, on/off ratios up to 600 and switching times of 100 milliseconds at gate voltages in the range of 1 V were obtained.
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| 5. |
- Bolin, Maria
(författare)
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Conjugated polymer surface switches for active cell control
- 2011
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Conjugated polymers have been found useful in a wide range of applications such as sensors, electrochemical transistors, solar cells, and printed electronics due to their mechanical, optical and electronic properties. An amazing research field has grown during the last three decades since the discovery of conducting polymers in 1976. Since the materials can be made from solutions, different processing methods such as spin coating and vapor phase polymerization can be used to coat a huge variety of substrates. The choice of method depends mainly on monomer solubility and kind of substrate to be coated. During the synthesis the polymers can be chemically modified to tailor their functionalities. Due to this variability in materials and the processability, electronics can be achieved on unconventional substrates such as flexible plastic foils and cell culturing dishes. As a contrast to inorganic, usually metallic materials, conducting polymers are built up from organic compounds in a molecular structure with soft mechanical properties that have shown to be a benefit in combination with biology, ranging from interactions with cells to interactions with advanced biological species such as tissues. This combination of research fields and the possible applications are merged within the field of organic bioelectronics.The primary purpose of this thesis is to give a background to organic electronics in general and how electrochemical devices can be processed and developed for biological applications in particular. An organic electronic surface switch is introduced to control cell adhesion and proliferation as well as an electrochemical transistor to spatially tune the cell adhesion along an electrochemical gradient. To mimic a more natural cell environment a three dimensional fiber substrate was used to design an electronically active matrix to promote nerve cell adhesion and communication. By combining standard microfabrication techniques and conjugated polymers desired patterns of electroactive polymer were created to enable active regulation of cell populations and their extracellular environment at high spatial resolution. Finally, a brief look into future challenges will also be presented.
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| 6. |
- Bubnova, Olga, et al.
(författare)
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Optimization of the thermoelectric figure of merit in the conducting polymer poly(3,4-ethylenedioxythiophene)
- 2011
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Ingår i: NATURE MATERIALS. - : Nature Publishing Group. - 1476-1122 .- 1476-4660. ; 10:6, s. 429-433
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Tidskriftsartikel (refereegranskat)abstract
- Thermoelectric generators (TEGs) transform a heat flow into electricity. Thermoelectric materials are being investigated for electricity production from waste heat (co-generation) and natural heat sources. For temperatures below 200 degrees C, the best commercially available inorganic semiconductors are bismuth telluride (Bi2Te3)-based alloys, which possess a figure of merit ZT close to one(1). Most of the recently discovered thermoelectric materials with ZT andgt; 2 exhibit one common property, namely their low lattice thermal conductivities(2,3). Nevertheless, a high ZT value is not enough to create a viable technology platform for energy harvesting. To generate electricity from large volumes of warm fluids, heat exchangers must be functionalized with TEGs. This requires thermoelectric materials that are readily synthesized, air stable, environmentally friendly and solution processable to create patterns on large areas. Here we show that conducting polymers might be capable of meeting these demands. The accurate control of the oxidation level in poly(3,4-ethylenedioxythiophene) (PEDOT) combined with its low intrinsic thermal conductivity (lambda = D 0.37W m(-1) K-1) yields a ZT = 0.25 at room temperature that approaches the values required for efficient devices.
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| 7. |
- Bubnova, Olga
(författare)
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Thermoelectric properties of conducting polymers
- 2013
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- According to different sources, from forty to sixty percent of the overall energy generated in the world today is squandered in waste heat. The existing energy conversion technologies are either close to their efficiency limits or too costly to justify their implementation. Therefore, the development of new technological approaches for waste heat recovery is highly demanded. The field of thermoelectrics can potentially provide an inexpensive, clean and efficient solution to waste heat underutilization, given that a new type of thermoelectric materials capable of meeting those requirements are available.This thesis reports on strategies to optimize a thermoelectric efficiency (ZT) of conducting polymers, more specifically poly(3,4-ethylenedioxythiophene) (Pedot). Conducting polymers constitute a special class of semiconductors characterized by low thermal conductivity as well as electrical conductivity and thermopower that can be readily modified by doping in order to achieve the best combination of thermoelectric parameters. Conducting polymers that have never previously been regarded as hypothetically compatible for thermoelectric energy conversion, can exhibit promising thermoelectric performance at moderate temperatures, which is a sought-after quality for waste heat recovery. A rather substandard thermoelectric efficiency of Pedot-Pss can be markedly improved by various secondary dopants whose addition usually improves polymer’s morphology accompanied by a drastic increase in electrical conductivity and, consequently, in ZT. In order to enable further enhancement in thermoelectric properties, the optimization of the charge carrier concentration is commonly used. The oxidation level of Pedot-Pss can be precisely controlled by electrochemical doping resulting in a tenfold increase of ZT. In contrast to Pedot-Pss, another conducting polymer Pedot-Tos exhibits superior thermoelectric performance even without secondary doping owning to its partially crystalline nature that allows for an improved electronic conduction. With the aid of a strong electron donor, positively doped Pedot-Tos gets partially reduced reaching the optimum oxidation state at which its thermoelectric efficiency is just four times smaller than that of Be2Te3 and the highest among all stable conducting polymers. The downsides associated with chemical doping of Pedot-Tos such as doping inhomogeneity or chemical dopants air sensitivity can be surmounted if the doping level of Pedot-Tos is controlled by acidity/basicity of the polymer. This approach yields similar maximum thermoelectric efficiency but does not necessitate inert conditions for sample preparation. Optimized Pedot-Tos/Pedot-Pss can be functionalized as a p-type material in organic thermogenerators (OTEG) to power low energy electronic devices. If printed on large areas, OTEGs could be used as an alternative technique for capturing heat discarded by industrial processes, households, transportation sector or any natural heat sources for electricity production.
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| 8. |
- Bubnova, Olga, et al.
(författare)
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Tuning the Thermoelectric Properties of Conducting Polymers in an Electrochemical Transistor
- 2012
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Ingår i: Journal of the American Chemical Society. - : American Chemical Society. - 0002-7863 .- 1520-5126. ; 134:40, s. 16456-16459
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Tidskriftsartikel (refereegranskat)abstract
- While organic field-effect transistors allow the investigation of interfacial charge transport at the semiconductor-dielectric interface, an electrochemical transistor truly modifies the oxidation level and conductivity throughout the bulk of an organic semiconductor. In this work, the thermoelectric properties of the bulk of the conducting polymer poly(3,4-ethylenedioxythiophene) -poly(styrene sulfonate) were controlled electrically by varying the gate voltage. In light of the growing interest in conducting polymers as thermoelectric generators, this method provides an easy tool to study the physics behind the thermoelectric properties and to optimize polymer thermoelectrics.
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| 9. |
- Cotrone, Serafina, et al.
(författare)
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Phospholipid film in electrolyte-gated organic field-effect transistors
- 2012
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Ingår i: Organic electronics. - : Elsevier. - 1566-1199 .- 1878-5530. ; 13:4, s. 638-644
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Tidskriftsartikel (refereegranskat)abstract
- A totally innovative electrolyte-gated field effect transistor, embedding a phospholipid film at the interface between the organic semiconductor and the gating solution, is described. The electronic properties of OFETs including a phospholipid film are studied in both pure water and in an electrolyte solution and compared to those of an OFET with the organic semiconductor directly in contact with the gating solution. In addition, to investigate the role of the lipid layers in the charge polarization process and quantify the field-effect mobility, impedance spectroscopy was employed. The results indicate that the integration of the biological film minimizes the penetration of ions into the organic semiconductor thus leading to a capacitive operational mode as opposed to an electrochemical one. The OFETs operate at low voltages with a field-effect mobility in the 10−3 cm2 V−1 s−1 range and an on/off current ratio of 103. This achievement opens perspectives to the development of FET biosensors potentially capable to operate in direct contact with physiological fluids.
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| 10. |
- Crispin, Xavier, et al.
(författare)
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Polyelectrolyte-Gated Organic Field-Effect Transistors
- 2010
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Ingår i: Iontronics. - Boca Raton : CRC Press; Taylor & Francis Group. - 9781439806883 - 9781439806890 ; , s. 193-218
-
Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- The field of organic electronics promises exciting new technologies based on inexpensive and mechanically flexible electronic devices. It has progressed over the past three decades to the point of commercial viability and is projected to grow to a 30 billion dollar market by the year 2015. Exploring new applications and device architectures, this book sets the tone for that exploration, gathering a community of experts in this area who are focused on the use of ionic functions to define the principle of operation in polymer devices. The contributors detail relevant technologies based on organic electronics, including polymer electrochromic devices and light-emitting electrochemical cells.
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