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Sökning: WFRF:(Engquist Isak)

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1.
  • Abdollahi Sani, Negar, et al. (författare)
  • A ferroelectric polymer introduces addressability in electrophoretic display cells
  • 2019
  • Ingår i: FLEXIBLE AND PRINTED ELECTRONICS. - : IOP PUBLISHING LTD. - 2058-8585. ; 4:3
  • Tidskriftsartikel (refereegranskat)abstract
    • During the last decades, tremendous efforts have been carried out to develop flexible electronics for a vast array of applications. Among all different applications investigated in this area, flexible displays have gained significant attention, being a vital part of large-area devices, portable systems and electronic labels etc electrophoretic (EP) ink displays have outstanding properties such as a superior optical switch contrast and low power consumption, besides being compatible with flexible electronics. However, the EP ink technology requires an active matrix-addressing scheme to enable exclusive addressing of individual pixels. EP ink pixels cannot be incorporated in low cost and easily manufactured passive matrix circuits due to the lack of threshold voltage and nonlinearity, necessities to provide addressability. Here, we suggest a simple method to introduce nonlinearity and threshold voltage in EP ink display cells in order to make them passively addressable. Our method exploits the nonlinearity of an organic ferroelectric capacitor that introduces passive addressability in display cells. The organic ferroelectric material poly(vinylidene fluoride-co-trifluoroethylene) (P(VDF-TrFE)) is here chosen because of its simple manufacturing protocol and good polarizability. We demonstrate that a nonlinear EP cell with bistable states can be produced by depositing a P(VDF-TrFE) film on the bottom electrode of the display cell. The P(VDF-TrFE) capacitor and the EP ink cell are separately characterized in order to match the surface charge at their respective interfaces and to achieve and optimize bistable operation of display pixels.
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2.
  • Abdollahi Sani, Negar, et al. (författare)
  • All-printed diode operating at 1.6 GHz
  • 2014
  • Ingår i: Proceedings of the National Academy of Sciences of the United States of America. - : National Academy of Sciences. - 0027-8424 .- 1091-6490. ; 111:33, s. 11943-11948
  • Tidskriftsartikel (refereegranskat)abstract
    • Printed electronics are considered for wireless electronic tags and sensors within the future Internet-of-things (IoT) concept. As a consequence of the low charge carrier mobility of present printable organic and inorganic semiconductors, the operational frequency of printed rectifiers is not high enough to enable direct communication and powering between mobile phones and printed e-tags. Here, we report an all-printed diode operating up to 1.6 GHz. The device, based on two stacked layers of Si and NbSi2 particles, is manufactured on a flexible substrate at low temperature and in ambient atmosphere. The high charge carrier mobility of the Si microparticles allows device operation to occur in the charge injection-limited regime. The asymmetry of the oxide layers in the resulting device stack leads to rectification of tunneling current. Printed diodes were combined with antennas and electrochromic displays to form an all-printed e-tag. The harvested signal from a Global System for Mobile Communications mobile phone was used to update the display. Our findings demonstrate a new communication pathway for printed electronics within IoT applications.
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3.
  • Abdollahi Sani, Negar, et al. (författare)
  • Flexible lamination-fabricated ultra-high frequency diodes based on self-supporting semiconducting composite film of silicon micro-particles and nano-fibrillated cellulose
  • 2016
  • Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 6
  • Tidskriftsartikel (refereegranskat)abstract
    • Low cost and flexible devices such as wearable electronics, e-labels and distributed sensors will make the future "internet of things" viable. To power and communicate with such systems, high frequency rectifiers are crucial components. We present a simple method to manufacture flexible diodes, operating at GHz frequencies, based on self-adhesive composite films of silicon micro-particles (Si-ÎŒPs) and glycerol dispersed in nanofibrillated cellulose (NFC). NFC, Si-ÎŒPs and glycerol are mixed in a water suspension, forming a self-supporting nanocellulose-silicon composite film after drying. This film is cut and laminated between a flexible pre-patterned Al bottom electrode and a conductive Ni-coated carbon tape top contact. A Schottky junction is established between the Al electrode and the Si-ÎŒPs. The resulting flexible diodes show current levels on the order of mA for an area of 2 mm2, a current rectification ratio up to 4 × 103 between 1 and 2 V bias and a cut-off frequency of 1.8 GHz. Energy harvesting experiments have been demonstrated using resistors as the load at 900 MHz and 1.8 GHz. The diode stack can be delaminated away from the Al electrode and then later on be transferred and reconfigured to another substrate. This provides us with reconfigurable GHz-operating diode circuits.
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4.
  • Belaineh, Dagmawi, et al. (författare)
  • Controlling the Organization of PEDOT:PSS on Cellulose Structures
  • 2019
  • Ingår i: ACS APPLIED POLYMER MATERIALS. - : AMER CHEMICAL SOC. - 2637-6105. ; 1:9, s. 2342-2351
  • Tidskriftsartikel (refereegranskat)abstract
    • Composites of biopolymers and conducting polymers are emerging as promising candidates for a green technological future and are actively being explored in various applications, such as in energy storage, bioelectronics, and thermoelectrics. While the device characteristics of these composites have been actively investigated, there is limited knowledge concerning the fundamental intracomponent interactions and the modes of molecular structuring. Here, by use of cellulose and poly(3,4-ethylene-dioxythiophene):poly(styrenesulfonate) (PEDOT:PSS), it is shown that the chemical and structural makeup of the surfaces of the composite components are critical factors that determine the materials organization at relevant dimensions. AFM, TEM, and GIVVAXS measurements show that when mixed with cellulose nanofibrils, PEDOT:PSS organizes into continuous nanosized beadlike structures with an average diameter of 13 nm on the nanofibrils. In contrast, when PEDOT:PSS is blended with molecular cellulose, a phase-segregated conducting network morphology is reached, with a distinctly relatively lower electric conductivity. These results provide insight into the mechanisms of PEDOT:PSS crystallization and may have significant implications for the design of conducting biopolymer composites for a vast array of applications.
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5.
  • Belaineh Yilma, Dagmawi, et al. (författare)
  • Printable carbon-based supercapacitors reinforced with cellulose and conductive polymers
  • 2022
  • Ingår i: Journal of Energy Storage. - : Elsevier Ltd. - 2352-152X .- 2352-1538. ; 50
  • Tidskriftsartikel (refereegranskat)abstract
    • Sustainable electrical energy storage is one of the most important scientific endeavors of this century. Battery and supercapacitor technologies are here crucial, but typically the current state of the art suffers from either lack of large-scale production possibilities, sustainability or insufficient performance and hence cannot match growing demands in society. Paper and cellulosic materials are mature scalable templates for industrial roll-to-roll production. Organic materials, such as conducting polymers, and carbon derivatives are materials that can be synthesized or derived from abundant sources. Here, we report the combination of cellulose, PEDOT:PSS and carbon derivatives for bulk supercapacitor electrodes adapted for printed electronics. Cellulose provides a mesoscopic mesh for the organization of the active ingredients. Furthermore, the PEDOT:PSS in combination with carbon provides superior device characteristics when comparing to the previously standard combination of activated carbon and carbon black. PEDOT:PSS acts as a mixed ion-electron conducting glue, which physically binds activated carbon particles together, while at the same time facilitating swift transport of both electrons and ions. A surprisingly small amount (10%) of PEDOT:PSS is needed to achieve an optimal performance. This work shows that cellulose added to PEDOT:PSS-carbon enables high-performing, mechanically stable, printed supercapacitor electrodes using a combination of printing methods.
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6.
  • Bertilsson, L, et al. (författare)
  • Adsorption of dimethyl methylphosphonate on self-assembled alkanethiolate monolayers
  • 1998
  • Ingår i: JOURNAL OF PHYSICAL CHEMISTRY B. - : AMER CHEMICAL SOC. - 1089-5647 .- 1520-6106 .- 1520-5207. ; 102:7, s. 1260-1269
  • Tidskriftsartikel (refereegranskat)abstract
    • The adsorption of dimethyl methylphosphonate (DMMP), a model molecule for sarin, on three different organic interfaces, prepared by solution self-assembly of alkanethiols on gold, was followed by a surface acoustic wave mass sensor and infrared reflection-absorption spectroscopy at room temperature. The surfaces, characterized by the following tail groups (-OH, -CH3, -COOH), show both quantitative and qualitative differences concerning the interaction with DMMP, the acid surface giving rise to the strongest adsorption. Results obtained in UHV, at low temperatures using infrared spectroscopy and temperature-programmed desorption, support this observation and give complementary information about the nature of the interaction. The hydrogen-bond-accepting properties of the P=O part of DMMP and its impact on the design of sensing interfaces based on hydrogen bonding, as well as the use of self-assembled monolayers to study molecular interactions, are discussed.
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7.
  • Bertilsson, Lars, et al. (författare)
  • Interaction of dimethyl methylphosphonate with alkanethiolate monolayers studied by temperature-programmed desorption and infrared spectroscopy
  • 1997
  • Ingår i: JOURNAL OF PHYSICAL CHEMISTRY B. - : AMER CHEMICAL SOC. - 1089-5647 .- 1520-6106 .- 1520-5207. ; 101:31, s. 6021-6027
  • Tidskriftsartikel (refereegranskat)abstract
    • The adsorption of dimethyl methylphosphonate (DMMP) on well-defined organic surfaces consisting of self-assembled monolayers (SAMs) of omega-substituted alkanethiolates on gold has been studied. Three different surfaces were examined: one terminated with -OH groups (Au/S-(CH2)(16)-OH), one with -CH3 (Au/S-(CH2)(15)-CH3), and one mixed surface with approximately equal amounts of -OH and -CH3 terminated thiols. Detailed information about the nature and strength of the interaction was gathered by infrared reflection-absorption spectroscopy and temperature-programmed desorption under ultrahigh-vacuum conditions. It is found that the outermost functional groups of the thiol monolayer have a pronounced impact on the interaction with DMMP at low coverage. The -OH surface, allowing for hydrogen bonds with the P=O part of the DMMP molecule, increases the strength of interaction by approximately 3.8 kJ/mol as compared to the -CH3 surface. A preadsorbed layer of D2O leads to stronger interaction on all surfaces. This is explained by additional hydrogen bond formation between free O-D at the ice-vacuum interface and DMMP.
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8.
  • Blaudeck, Thomas, et al. (författare)
  • Simplified Large-Area Manufacturing of Organic Electrochemical Transistors Combining Printing and a Self-Aligning Laser Ablation Step
  • 2012
  • Ingår i: Advanced Functional Materials. - : Wiley-VCH Verlag Berlin. - 1616-301X .- 1616-3028. ; 22:14, s. 2939-2948
  • 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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9.
  • Brooke, Robert, et al. (författare)
  • Controlling the electrochromic properties of conductive polymers using UV-light
  • 2018
  • Ingår i: Journal of Materials Chemistry C. - : ROYAL SOC CHEMISTRY. - 2050-7526 .- 2050-7534. ; 6:17, s. 4663-4670
  • Tidskriftsartikel (refereegranskat)abstract
    • The phenomenon of electrochromism in conductive polymers is well known and has been exploited in many scientific reports. Using a newly developed patterning technique for conductive polymers, we manufactured high-resolution electrochromic devices from the complementary polymers PEDOT and polypyrrole. The technique, which combines UV-light exposure with vapor phase polymerization, has previously only been demonstrated with the conductive polymer PEDOT. We further demonstrated how the same technique can be used to control the optical properties and the electrochromic contrast in these polymers. Oxidant exposure to UV-light prior to vapor phase polymerization showed a reduction in polymer electrochromic contrast allowing high-resolution (100 mu m) patterns to completely disappear while applying a voltage bias due to their optical similarity in one redox state and dissimilarity in the other. This unique electrochromic property enabled us to construct devices displaying images that appear and disappear with the change in applied voltage. Finally, a modification of the electrochromic device architecture permitted a dual image electrochromic device incorporating patterned PEDOT and patterned polypyrrole on the same electrode, allowing the switching between two different images.
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10.
  • Brooke, Robert, 1989-, et al. (författare)
  • Greyscale and paper electrochromic polymer displays by UV patterning
  • 2019
  • Ingår i: Polymers. - : MDPI AG. - 2073-4360. ; 11:2
  • Tidskriftsartikel (refereegranskat)abstract
    • Electrochromic devices have important implications as smart windows for energy efficient buildings, internet of things devices, and in low-cost advertising applications. While inorganics have so far dominated the market, organic conductive polymers possess certain advantages such as high throughput and low temperature processing, faster switching, and superior optical memory. Here, we present organic electrochromic devices that can switch between two high-resolution images, based on UV-patterning and vapor phase polymerization of poly(3,4- ethylenedioxythiophene) films. We demonstrate that this technique can provide switchable greyscale images through the spatial control of a UV-light dose. The color space was able to be further altered via optimization of the oxidant concentration. Finally, we utilized a UV-patterning technique to produce functional paper with electrochromic patterns deposited on porous paper, allowing for environmentally friendly electrochromic displays.
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11.
  • Brooke, Robert, 1989-, et al. (författare)
  • Nanocellulose and PEDOT:PSS composites and their applications
  • 2023
  • Ingår i: Polymer Reviews. - : Taylor and Francis Ltd.. - 1558-3724 .- 1558-3716. ; :2, s. 437-
  • Tidskriftsartikel (refereegranskat)abstract
    • The need for achieving sustainable technologies has encouraged research on renewable and biodegradable materials for novel products that are clean, green, and environmentally friendly. Nanocellulose (NC) has many attractive properties such as high mechanical strength and flexibility, large specific surface area, in addition to possessing good wet stability and resistance to tough chemical environments. NC has also been shown to easily integrate with other materials to form composites. By combining it with conductive and electroactive materials, many of the advantageous properties of NC can be transferred to the resulting composites. Conductive polymers, in particular poly(3,4-ethylenedioxythiophene:poly(styrene sulfonate) (PEDOT:PSS), have been successfully combined with cellulose derivatives where suspensions of NC particles and colloids of PEDOT:PSS are made to interact at a molecular level. Alternatively, different polymerization techniques have been used to coat the cellulose fibrils. When processed in liquid form, the resulting mixture can be used as a conductive ink. This review outlines the preparation of NC/PEDOT:PSS composites and their fabrication in the form of electronic nanopapers, filaments, and conductive aerogels. We also discuss the molecular interaction between NC and PEDOT:PSS and the factors that affect the bonding properties. Finally, we address their potential applications in energy storage and harvesting, sensors, actuators, and bioelectronics. © 2022 The Author(s). 
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12.
  • Brooke, Robert, 1989-, et al. (författare)
  • Supercapacitors on demand : All-printed energy storage devices with adaptable design
  • 2019
  • Ingår i: Flexible and Printed Electronics. - : Institute of Physics Publishing. - 2058-8585. ; 4:1
  • Tidskriftsartikel (refereegranskat)abstract
    • Demands on the storage of energy have increased for many reasons, in part driven by household photovoltaics, electric grid balancing, along with portable and wearable electronics. These are fast-growing and differentiated applications that need large volume and/or highly distributed electrical energy storage, which then requires environmentally friendly, scalable and flexible materials and manufacturing techniques. However, the limitations on current inorganic technologies have driven research efforts to explore organic and carbon-based alternatives. Here, we report a conducting polymer:cellulose composite that serves as the active material in supercapacitors which has been incorporated into all-printed energy storage devices. These devices exhibit a specific capacitance of ≈90 F g -1 and an excellent cyclability (>10 000 cycles). Further, a design concept coined 'supercapacitors on demand' is presented, which is based on a printing-cutting-folding procedure, that provides us with a flexible production protocol to manufacture supercapacitors with adaptable configuration and electrical characteristics.
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13.
  • Chen, Shangzhi, et al. (författare)
  • Redox-tunable structural colour images by UV-patterned conducting polymer nanofilms on metal surfaces
  • Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
    • Precise manipulation of light-matter interaction has enabled a wide variety of approaches to create bright and vivid structural colours. Techniques utilizing photonic crystals, Fabry-Pérot cavities, plasmonics, or high-refractive index dielectric metasurfaces have been studied for applications ranging from optical coatings to reflective displays. However, complicated fabrication procedures for sub-wavelength nanostructures, limited active areas, and inherent absence of tunability of these approaches significantly impede their further development towards flexible, large-scale, and switchable devices compatible with facile and cost-effective production. Herein, we present a simple and efficient method to generate structural colours based on nanoscale conducting polymer films prepared on metallic surfaces via vapour phase polymerization and ultraviolet (UV) light patterning. Varying the UV dose enables synergistic control of both nanoscale film thickness and polymer permittivity, which generates controllable colours from violet to red. Together with greyscale photomasks this enables fabrication of high-resolution colour images using single exposure steps. We further demonstrate spatiotemporal tuning of the structurally coloured surfaces and images via electrochemical modulation of the polymer redox state. The simple structure, facile fabrication, wide colour gamut, and dynamic colour tuning make this concept competitive for future multi-functional and smart displays.
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14.
  • Chen, Shangzhi, et al. (författare)
  • Tunable Structural Color Images by UV-Patterned Conducting Polymer Nanofilms on Metal Surfaces.
  • 2021
  • Ingår i: Advanced Materials. - : Wiley. - 0935-9648 .- 1521-4095. ; 33:33
  • Tidskriftsartikel (refereegranskat)abstract
    • Precise manipulation of light-matter interactions has enabled a wide variety of approaches to create bright and vivid structural colors. Techniques utilizing photonic crystals, Fabry-Pérot cavities, plasmonics, or high-refractive-index dielectric metasurfaces have been studied for applications ranging from optical coatings to reflective displays. However, complicated fabrication procedures for sub-wavelength nanostructures, limited active areas, and inherent absence of tunability of these approaches impede their further development toward flexible, large-scale, and switchable devices compatible with facile and cost-effective production. Here, a novel method is presented to generate structural color images based on monochromic conducting polymer films prepared on metallic surfaces via vapor phase polymerization and ultraviolet (UV) light patterning. Varying the UV dose enables synergistic control of both nanoscale film thickness and polymer permittivity, which generates controllable structural colors from violet to red. Together with grayscale photomasks this enables facile fabrication of high-resolution structural color images. Dynamic tuning of colored surfaces and images via electrochemical modulation of the polymer redox state is further demonstrated. The simple structure, facile fabrication, wide color gamut, and dynamic color tuning make this concept competitive for applications like multifunctional displays.
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15.
  • Edberg, Jesper, et al. (författare)
  • Boosting the capacity of all-organic paper supercapacitors using wood derivatives
  • 2018
  • Ingår i: Journal of Materials Chemistry A. - : Royal Society of Chemistry (RSC). - 2050-7488 .- 2050-7496. ; 6:1, s. 145-152
  • Tidskriftsartikel (refereegranskat)abstract
    • Printed and flexible organic electronics is a steadily expanding field of research and applications. One of the most attractive features of this technology is the possibility of large area and high throughput production to form low-cost electronics on different flexible substrates. With an increasing demand for sustainable energy production, low-cost and large volume technologies to store high-quality energy become equally important. These devices should be environmentally friendly with respect to their entire life cycle. Supercapacitors and batteries based on paper hold great promise for such applications due to the low cost and abundance of cellulose and other forest-derived components. We report a thick-film paper-supercapacitor system based on cellulose nanofibrils, the mixed ion-electron conducting polymer PEDOT: PSS and sulfonated lignin. We demonstrate that the introduction of sulfonated lignin into the cellulose-conducting polymer system increases the specific capacitance from 110 to 230 F g(-1) and the areal capacitance from 160 mF cm(-2) to 1 F cm(-2). By introducing lignosulfonate also into the electrolyte solution, equilibrium, with respect to the concentration of the redox molecule, was established between the electrode and the electrolyte, thus allowing us to perform beyond 700 charge/discharge cycles with no observed decrease in performance.
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16.
  • Edberg, Jesper, et al. (författare)
  • Electrochemical circuits from 'cut and stick' PEDOT : PSS-nanocellulose composite
  • 2017
  • Ingår i: Flexible and Printed Electronics. - : Institute of Physics Publishing (IOPP). - 2058-8585. ; 2:4
  • Tidskriftsartikel (refereegranskat)abstract
    • We report a flexible self-standing adhesive composite made from PEDOT:PSS and nanofibrillated cellulose. The material exhibits good combined mechanical and electrical characteristics (an elastic modulus of 4.4 MPa, and an electrical conductivity of 30 S cm(-1)). The inherent self-adhesiveness of the material enables it to be laminated and delaminated repeatedly to form and reconfigure devices and circuits. This modular property opens the door for a plethora of applications where reconfigurability and ease-of-manufacturing are of prime importance. We also demonstrate a paper composite with ionic conductivity and combine the two materials to construct electrochemical devices, namely transistors, capacitors and diodes with high values of transconductance, charge storage capacity and current rectification. We have further used these devices to construct digital circuits such as NOT, NAND and NORlogic.
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17.
  • Edberg, Jesper, 1988- (författare)
  • Flexible and Cellulose-based Organic Electronics
  • 2017
  • Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
    • Organic electronics is the study of organic materials with electronic functionality and the applications of such materials. In the 1970s, the discovery that polymers can be made electrically conductive led to an explosion within this field which has continued to grow year by year. One of the attractive features of organic electronic materials is their inherent mechanical flexibility, which has led to the development of numerous flexible electronics technologies such as organic light emitting diodes and solar cells on flexible substrates. The possibility to produce electronics on flexible substrates like plastic or paper has also had a large impact on the field of printed, electronics where inks with electronic functionality are used for large area fabrication of electronic devices using classical printing methods, such as screen printing, inkjet printing and flexography.Recently, there has been a growing interest in the use of cellulose in organic and printed electronics, not only as a paper substrate but also as a component in composite materials where the cellulose provides mechanical strength and favorable 3D-microstructures. Nanofibrillated cellulose is composed of cellulose fibers with high aspect-ratio and diameters in the nanometer range. Due to its remarkable mechanical strength, large area-to-volume ratio, optical transparency and solution processability it has been widely used as a scaffold or binder for electronically active materials in applications such as batteries, supercapacitors and optoelectronics.The focus of this thesis is on flexible devices based on conductive polymers and can be divided into two parts: (1) Composite materials of nanofibrillated cellulose and the conductive polymer PEDOT:PSS and (2) patterning of vapor phase polymerized conductive polymers. In the first part, it is demonstrated how the combination of cellulose and conductive polymers can be used to make electronic materials of various form factors and functionality. Thick, freestanding and flexible “papers” are used to realize electrochemical devices such as transistors and supercapacitors while lightweight, porous and elastic aerogels are used for sensor applications. The second focus of the thesis is on a novel method of patterning conductive polymers produced by vapor phase polymerization using UV-light. This method is used to realize flexible electrochromic smart windows with high-resolution images and tunable optical contrast.
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18.
  • Edberg, Jesper, et al. (författare)
  • Improving the Performance of Paper Supercapacitors Using Redox Molecules from Plants
  • 2019
  • Ingår i: ADVANCED SUSTAINABLE SYSTEMS. - : WILEY-V C H VERLAG GMBH. - 2366-7486. ; 3:8
  • Tidskriftsartikel (refereegranskat)abstract
    • A supercapacitor made from organic and nature-based materials, such as conductive polymers (PEDOT:PSS), nanocellulose, and an the organic dye molecule (alizarin), is demonstrated. The dye molecule, which historically was extracted from the roots of the plant rubia tinctorum, is here responsible for the improvement in energy storage capacity, while the conductive polymer provides bulk charge transport within the composite electrode. The forest-based nanocellulose component provides a mechanically strong and nonporous network onto which the conductive polymer self-organizes. The electrical and electrochemical properties of the material composition are investigated and prototype redox-enhanced supercapacitor devices with excellent specific capacitance exceeding 400 F g(-1) and an operational stability over >1000 cycles are demonstrated. This new class of supercapacitors, which in part are based on organic materials from plants, represents an important step toward a green and sustainable energy technology.
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19.
  • Edberg, Jesper, et al. (författare)
  • Patterning and Conductivity Modulation of Conductive Polymers by UV Light Exposure
  • 2016
  • Ingår i: Advanced Functional Materials. - : WILEY-V C H VERLAG GMBH. - 1616-301X .- 1616-3028. ; 26:38, s. 6950-6960
  • Tidskriftsartikel (refereegranskat)abstract
    • A novel patterning technique of conductive polymers produced by vapor phase polymerization is demonstrated. The method involves exposing an oxidant film to UV light which changes the local chemical environment of the oxidant and subsequently the polymerization kinetics. This procedure is used to control the conductivity in the conjugated polymer poly(3,4-ethylenedioxythiophene): tosylate by more than six orders of magnitude in addition to producing high-resolution patterns and optical gradients. The mechanism behind the modulation in the polymerization kinetics by UV light irradiation as well as the properties of the resulting polymer are investigated.
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20.
  • Engquist, Isak, et al. (författare)
  • D2O ice on controlled wettability self-assembled alkanethiolate monolayers : Cluster formation and substrate-adsorbate interaction
  • 1996
  • Ingår i: JOURNAL OF PHYSICAL CHEMISTRY. - : AMER CHEMICAL SOC. - 0022-3654 .- 1541-5740. ; 100:51, s. 20089-20096
  • Tidskriftsartikel (refereegranskat)abstract
    • Infrared reflection-absorption spectroscopy is used to investigate thin (1-200 Angstrom average thickness) overlayers of D2O ice deposited in ultrahigh vacuum on controlled wettability self-assembled monolayers. The monolayers were derived from mixed solutions of HS(CH2)(15)CH3 and HS(CH2)(16)OH, making it possible to examine the whole range of samples from f(OH) = 0.0 to f(OH) 1.0, where f(OH) denotes the molar fraction of OH-terminated thiols in the preparation solution. This paper focuses on the interaction between the ice and the monolayer. It is shown that water molecules do not penetrate into the monolayer but that two types of interaction with the chain-terminating groups occur: hydrogen bond formation with surface hydroxyls and weak dipole-dipole interaction with surface methyls. For surfaces with f(OH) less than 0.3, the latter interaction causes the free OD mode, normally observed at 2729 cm(-1), to shift to 2704 cm(-1), thereby providing a spectral signature feature whose intensity is directly proportional to the relative area of the ice/monolayer interface. Quantitative analysis of the infrared spectra suggests that ice clusters are essentially flat on surfaces with 0.6 less than f(OH) less than 1.0 and become more droplet-like for decreasing f(OH) below 0.6. On f(OH) = 0.0 surfaces, the microscopic clusters display high contact angles (similar to 120 degrees), and full surface coverage does not occur until the average overlayer thickness is 150-200 Angstrom.
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21.
  • Engquist, Isak, et al. (författare)
  • Highly conducting nanographite-filled paper fabricated via standard papermaking techniques
  • 2020
  • Ingår i: ACS Applied Materials and Interfaces. - : American Chemical Society. - 1944-8244 .- 1944-8252. ; 12:43, s. 48828-48835
  • Tidskriftsartikel (refereegranskat)abstract
    • Eco-friendly and cost-effective materials and processes to manufacture functional substrates are crucial to further advance the area of printed electronics. One potential key component in the printed electronics platform is an electrically functionalized paper, produced by simply mixing common cellulosic pulp fibers with high-performance electroactive materials. Herein, an electronic paper including nanographite has been prepared using a standardized and scalable papermaking technique. No retention aid was needed to achieve a conducting nanographite loading as high as 50 wt %. The spontaneous retention that provides the integrity and stability of the nanographite paper, likely originates partially from an observed water-stable adhesion of nanographite flakes onto the fiber surfaces. The resulting paper exhibits excellent electrical characteristics, such as an in-plane conductivity of 107 S/cm and an areal capacitance of 9.2 mF/cm2, and was explored as the back-electrode in printed electrochromic displays.
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22.
  • Engquist, Isak, et al. (författare)
  • Hydrogen Bond Interaction between Self-Assembled Monolayers and Adsorbed Water Molecules and Its Implications for Cluster Formation
  • 1995
  • Ingår i: Journal of Physical Chemistry B. - : AMER CHEMICAL SOC. - 1520-6106 .- 1520-5207 .- 0022-3654 .- 1541-5740. ; 99:39, s. 14198-14200
  • Tidskriftsartikel (refereegranskat)abstract
    • Infrared spectroscopy is used to investigate the adsorption of D2O onto self-assembled monolayers of methyl 16-mercaptohexadecanoate on gold. The D2O molecules are shown to interact with the carbonyl oxygens of the monolayer, forming hydrogen bonds and causing a structural rearrangement of the CO2CH3 terminal group. The number of hydrogen bonds decreases as the amorphous-like, essentially flat (two-dimensional) ice overlayer that forms at 100 K changes into polycrystalline-like ice upon annealing at 140 K. This decrease is a consequence of the formation of three-dimensional ice clusters, which leaves a large fraction of the monolayer surface bare.
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23.
  • Engquist, Isak, et al. (författare)
  • Infrared characterization of amorphous and polycrystalline D2O ice on controlled wettability self-assembled alkanethiolate monolayers
  • 1997
  • Ingår i: Journal of Chemical Physics. - : American Institute of Physics (AIP). - 0021-9606 .- 1089-7690. ; 106:8, s. 3038-3048
  • Tidskriftsartikel (refereegranskat)abstract
    • Infrared reflection-absorption spectroscopy has been used to characterize thin overlayers (1-200 Angstrom) of D2O ice deposited in UHV onto a set of self-assembled alkanethiolate monolayers (SAMs) of controlled wettabilities on gold. The SAMs were prepared from a series of controlled composition, mixed solutions of HS(CH2)(15)CH3 and HS(CH2)(16)OH, making it possible to investigate the whole wettability range from theta approximate to 0 degrees to theta=112 degrees, where theta is the static contact angle with water. Dosing of D2O and infrared measurements were carried out at selected sample temperatures between 82 and 150 K. Experimental spectra of ice overlayers recorded below 100 K on all SAM substrates are in good agreement with simulated reflection-absorption spectra, derived from the optical constants of amorphous ice. This agreement allows accurate film thickness determination. In contrast, lack of correspondence in spectral signature is noted between the spectra of annealed films and simulated polycrystalline (or amorphous) ice spectra. We interpret this discrepancy to suggest that significant substrate-induced differences between thin overlayers and bulk ice persist in the latter case. Spectral indications of ice-substrate interaction are also seen for amorphous ice, and are especially prominent in the case of highly hydrophobic (pure CH3-terminated, theta=112 degrees) substrates. In this case the substrate effect extends up to an average film thickness (150-200 Angstrom) corresponding to similar to 50 ice monolayers, in contrast to highly hydrophilic OH-terminated substrate, where the substrate effects appear to vanish beyond similar to 5 monolayers (15-20 Angstrom average thickness). Annealing of thin ice overlayers (2-3 monolayers) clearly demonstrates a strong correlation between the onset as well as progression of the transition from amorphous to polycrystalline ice and the exact substrate wettability or chemical composition. The data further suggest the existence of metastable intermediate forms, that are neither purely amorphous nor polycrystalline. We discuss these observations in terms of substrate-overlayer interaction. A tentative phase diagram summarizing these results is presented. (C) 1997 American Institute of Physics.
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24.
  • Engquist, Isak, et al. (författare)
  • Microscopic wettability of ester- and acetate-terminated self-assembled monolayers
  • 1997
  • Ingår i: Langmuir. - : American Chemical Society. - 0743-7463 .- 1520-5827. ; 13:15, s. 4003-4012
  • Tidskriftsartikel (refereegranskat)abstract
    • Four different carbonyl-containing self-assembled monolayers (SAMs) of alkanethiolates on gold were studied to assess the impact of the functional group Linked to the carbonyl upon its hydrogen bond accepting capability. These SAMs (HS(CH2)(16)O(C=O)-X,X = CH3, CF3, or C6H5, and HS(CH2)(15)(C=O)OCH3) were thoroughly characterized with contact angle measurements, single wavelength ellipsometry, and infrared reflection-absorption spectroscopy (IRAS) prior to the studies of interaction with D2O. The first three monolayer compounds were introduced by reacting hydroxyl-terminated SAMs (HS(CH2)(16)OH) with either acetyl chloride, trifluoroacetic anhydride, or benzoyl chloride. The behavior of D2O ice on the SAMs was investigated at 100 K with IRAS and temperature programmed desorption (TPD). On all monolayers the D2O molecules were shown to interact with the carbonyl oxygen. The degree of interaction depended upon the termination of the thiol, where the size, structure, and electronegativity of the terminating groups in the molecules comprising the monolayer were found to be important factors. Indications of interaction with the C-O-C oxygen were seen for all compounds, as well as weak interaction between water molecules and the CF3 group of one of the investigated SAMs. Common behavior for all four monolayers with an adsorbed D2O overlayer was a decrease in the number of hydrogen bonds to the substrate when the overlayer was annealed from amorphous ice at 100 K to polycrystalline-like ice at 140 K. The spectral changes accompanying the structural transition were consistent with a change from a mainly flat overlayer to condensed three-dimensional clusters. The bulk-to-surface molecular ratio of adsorbed ice clusters could be assessed by IRAS and correlated to macroscopic wetting properties. Our results infer that microscopic ice clusters on these SAMs qualitatively mimic the shape of macroscopic water drops on the same SAMs. Results of TPD measurements are also consistent with this view.
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25.
  • Engquist, Isak, et al. (författare)
  • Temperature-programmed desorption and infrared studies of D2O ice on self-assembled alkanethiolate monolayers : influence of substrate wettability
  • 1995
  • Ingår i: JOURNAL OF PHYSICAL CHEMISTRY. - : AMER CHEMICAL SOC. - 0022-3654 .- 1541-5740. ; 99:32, s. 12257-12267
  • Tidskriftsartikel (refereegranskat)abstract
    • This paper examines the relationship between the thermal desorption of thin overlayers of condensed D2O ice and the wettability properties of the supporting substrate surface. Mixed self-assembled monolayers (SAMs) on gold with controlled chemical composition and wettability (-0.4 less than cos theta less than 1.0, where theta represents the static contact angle with water) derived from HS(CH2)(16)OH and HS(CH2)(15)CH3 were used as model surfaces. The D2O ice overlayers were prepared on these substrates by dosing of 0.1-30 langmuirs of D2O in ultrahigh vacuum at 80-120 K and characterized with temperature-programmed desorption (TPD). Infrared reflection-absorption spectroscopy (IRAS) was also used to characterize the structural progressions within the overlayers during the course of the TPD experiments, as well as at selected temperatures before and after annealing of the overlayer structure. The IRAS data show that amorphous-like ice is formed at sufficiently low temperatures (less than or equal to 100 K) on all mixed SAMs, regardless of their wettability. A structural transition of the D2O ice from amorphous-like to polycrystalline-like is observed above 100 K. The exact onset of the transition is strongly dependent on the wettability and varies from about 110 K on the extreme hydrophobic (CH3) substrate to 145-150 K on the hydrophilic (OH) substrate. On the most hydrophilic substrates, the strong hydrogen bond interaction with surface hydroxyls prevents completion of the structural transition before desorption of the D2O overlayer. This type of pinning of the D2O molecules to the substrate surface is most likely responsible for the sharp increase in desorption energy of similar to 0.2 kcal/mol which is seen at cos theta approximate to 0.6, a value defining the hydrophilicity limit above which, for our set of experimental parameters, the transition is no longer completed. The TPD data also support a model of the D2O overlayer as forming clusters of very different shape depending on substrate wettability-flat, two-dimensional clusters on hydrophilic SAMs and dropletlike, three-dimensional clusters on hydrophobic SAMs.
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26.
  • Fabiano, Simone, et al. (författare)
  • Ferroelectric polarization induces electronic nonlinearity in ion-doped conducting polymers
  • 2017
  • Ingår i: Science Advances. - : American Association for the Advancement of Science. - 2375-2548. ; 3:6
  • Tidskriftsartikel (refereegranskat)abstract
    • Poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS) is an organic mixed ion-electron conducting polymer. The PEDOT phase transports holes and is redox-active, whereas the PSS phase transports ions. When PEDOT is redox-switched between its semiconducting and conducting state, the electronic and optical properties of its bulk are controlled. Therefore, it is appealing to use this transition in electrochemical devices and to integrate those into large-scale circuits, such as display or memory matrices. Addressability and memory functionality of individual devices, within these matrices, are typically achieved by nonlinear current-voltage characteristics and bistability—functions that can potentially be offered by the semiconductor-conductor transition of redox polymers. However, low conductivity of the semiconducting state and poor bistability, due to self-discharge, make fast operation and memory retention impossible. We report that a ferroelectric polymer layer, coated along the counter electrode, can control the redox state of PEDOT. The polarization switching characteristics of the ferroelectric polymer, which take place as the coercive field is overcome, introduce desired nonlinearity and bistability in devices that maintain PEDOT in its highly conducting and fast-operating regime. Memory functionality and addressability are demonstrated in ferro-electrochromic display pixels and ferro-electrochemical transistors. 
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27.
  • Isacsson, Patrik Anders Gustav, et al. (författare)
  • Electrochemical characteristics of lignin in CTMP for paper battery electrodes.
  • 2024
  • Ingår i: ChemSusChem. - 1864-5631 .- 1864-564X.
  • Tidskriftsartikel (refereegranskat)abstract
    • Lignin has been extensively researched as a cathode active material in secondary batteries. In the present work, the energy storage potential of lignin naturally present in papers made of chemi-thermomechanical pulp (CTMP) is explored. More specifically, effects from CTMP fines on the electrochemical characteristics have been studied. Compared to pulp fibers, fines are higher in lignin content and have higher specific surface area. It was expected that this would be positive for the electrode performance; however, the result points to the opposite. The fines do not significantly contribute to a higher lignin specific capacity, and they deteriorate the cycling stability. Higher fines content was found to result in a higher oxidative activity as well as more abundant competing reactions. These competing reactions are believed to be linked to the cycle stability. Therefore, we hypothesize that the electrochemical stability of lignin can be better understood by studying differences between fines and fiber lignin. As the theoretical specific capacity of this material is about 20 times larger than obtained here, identification of the reasons for this capacity discrepancy is needed to realize the full potential of lignin-based paper batteries.
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28.
  • Isacsson, Patrik, 1991- (författare)
  • Materials Design for Paper Electrodes : A Papermaking Perspective on Electrode Fabrication
  • 2024
  • Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
    • The electrification and digitalization of our society has propelled the demand for energy storage solutions. High-end technologies have been developed to satisfy the requirements of demanding applications, such as electromobility and portable consumer electronics, which also increasingly find markets for less demanding applications. These markets include grid and domestic energy storage, as well as Internet of Things (IoT). However, using high-end technologies for low-end applications is a waste of resources that puts unnecessary stress on the supply lines. Thus, more low-cost cost and environmentally friendly alternative technologies are sought, among which renewable biobased materials derived from agriculture and forestry play a prominent role.The dominant chemical constituents in plants, cellulose and lignin, exhibit some intriguing electrochemical and colloidal properties. Cellulose has been found to efficiently stabilize various electronic materials, whereas lignin can be used as an electronic material itself. Lignocellulosic materials also open for papermaking as an alternative manufacturing approach. Taking the step to using papermaking methods is, however, a bit far from the technology readiness level, as the vast majority of the research on paper electrodes is based on nanocellulose. The material properties of such nanopapers are indeed extraordinary, but the lack of large-scale production methods for nanopapers is a serious challenge.To circumvent this obstacle and find a shortcut to the realization of paper electrodes, this thesis has turned to conventional papermaking techniques. Fibres are essentially different to nanofibrils by their difference in size, and the papermaking process requires careful composition of the formulations. Thus, as the research on nanopaper electrodes cannot be directly translated into conventional papermaking techniques, this calls for separate studies on fibre-based systems.This thesis is based on four separate works carried out by an explorative approach, where different kinds of paper electrodes have been investigated with touchdowns in example applications. Based on these studies, general knowledge has been concluded. This has been summarized by four important aspects for materials design of paper electrodes:Colloidal Systems. The paper electrode formulations exhibit both familiar and unfamiliar colloidal interactions. Established wet-end chemistry including charge balance control and electrostatic interactions remain important in parallel with unconventional behaviours. Exfoliated graphite forms water-stable coatings around pulp fibres and exhibit auto-retention mechanism(s). The conducting polymer system PEDOT:PSS, which can adsorb to chemical pulp fibres, does not exhibit affinity to chemi-thermomechanical pulp.Percolating Networks. Cellulosic fibres constitute an insulative matrix, in which efficient percolating conductive networks must be formed. The way a conducting additive is introduced, as well as the morphology of the additive, is important. Combining conducting polymers with nanocarbons is a promising concept for material-efficient networks. For a filler used as an electrode active material, it is important to acknowledge whether it is electronically conductive or not. A higher amount of conductive additives is required for insulative electrode active materials than for those with internal conductivity.Lignin Electrochemistry. Residual lignin present in softwood pulps, in both mechanical and chemical pulps, is electrochemically active. This can either be wanted or unwanted depending on application. Fines differ from fibres in terms of electrochemical stability and oxidative activity. Substantial competing electrochemical reactions occur, which might be related to the electrochemical stability.Mechanical Properties. Percolating conductive networks require high interconnectivity, which entails a cross-linked structure. This brings increased stiffness to the papers, which can be observed both for exfoliated graphite as a filler as well as for papers impregnated with PEDOT:PSS.Based on the four aspects described above, prospects for a few paper electrode applications have been reviewed. The prospects are mixed, each with their own challenges and opportunities which requires further research and development. While this thesis can conclude that we have not yet reached the point where paper electrodes can be realized, it certainly paves the way to get there.
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29.
  • Isacsson, Patrik, et al. (författare)
  • Production of energy-storage paper electrodes using a pilot-scale paper machine
  • 2022
  • Ingår i: Journal of Materials Chemistry A. - : Royal Society of Chemistry. - 2050-7488 .- 2050-7496. ; 10:40, s. 21579-21589
  • Tidskriftsartikel (refereegranskat)abstract
    • The global efforts in electrifying our society drive the demand for low-cost and sustainable energy storage solutions. In the present work, a novel material concept was investigated to enable fabrication of several 10 meter-long rolls of supercapacitor paper electrodes on a pilot-scale paper machine. The material concept was based on cationized, cellulose-rich wood-derived fibres, conducting polymer PEDOT:PSS, and activated carbon filler particles. Cationic fibres saturated with anionic PEDOT:PSS provide a conducting scaffold hosting the activated carbon, which functions as the active charge-storage material. The response from further additives was systematically investigated for several critical paper properties. Cellulose nanofibrils were found to improve mechanical properties, while carbon black enhanced both the conductivity and the storage capacity of the activated carbon, reaching a specific capacitance of 67 F g−1. This pilot trial shows that “classical” papermaking methods are fit for the purpose and provides valuable insights on how to further advance bio-based energy storage solutions for large-scale applications.
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30.
  • Israr, Muhammad Qadir, et al. (författare)
  • Structural characterization and biocompatible applications of graphene nanosheets for miniaturization of potentiometric cholesterol biosensor
  • 2011
  • Ingår i: Journal of Biosensors & Bioelectronics. - : OMICS Publishing Group. - 2155-6210. ; 2:3
  • Tidskriftsartikel (refereegranskat)abstract
    • The potentiometric cholesterol biosensor based on graphene nanosheets has been successfully miniaturized. Cholesterol oxidase (ChOx) has been immobilized onto graphene nanosheets exfoliated on copper wire through the process of physical adsorption,. The presented potentiometric biosensor renders effective selectivity and sensitivity (~82 mV/decade) for the detection of cholesterol biomolecules in 1 × 10−6 M to 1 × 10−3 M logarithmic range and quick output response within ~ 4 sec. The stability and reusability of the biosensor has also been investigated for the above mentioned range of cholesterol concentrations. The enzyme activity measurements on graphene nanosheets are studied using UV-Visible and FTIR spectrophotometers. Additionally, the functioning of the presented biosensor is studied for a range of temperatures (15-70 °C) and pH values (4-9).
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31.
  • Jafari, Mohammad Javad, 1984- (författare)
  • Application of Vibrational Spectroscopy in Organic Electronics
  • 2017
  • Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
    • The rapid technological developments enforce us to live in an increasingly electronic world, and the revolutionary usage of conjugated polymers in electronics in the late 1970s accelerated these developments, based on the unique characteristics of conjugated polymers, such as low cost, easy processing, mechanical flexibility, large-area application and compatibility with a variety of substrates. Organic electronic devices are commercially available in the form of, for example, solar cells, transistors, and organic light-emitting diode (OLED) displays. Scientists work on electroactive polymers to enhance their chemical, electrical and mechanical properties, to improve parameters such as charge carrier mobility and doping capacity, in order to reach acceptable efficiency and stability to fabricate organic electronic devices. A comprehensive understanding of the changes in chemical structure, in response to external factors such as applied potential and temperature gradients, which can disturb the chemical equilibrium of the constituent materials, and of the conduction mechanisms of the operating devices, can help to enhance the performance of organic electronics devices. Vibrational spectroscopy is a powerful analytical method for in-situ monitoring of such chemical or electrochemical reactions and associated structural changes of conjugated polymers in a working device.In this thesis, Fourier-transform infrared (FTIR) spectroscopy has been used to study the structural changes in electroactive organic materials, in response to chemical or electrochemical reactions, and to study electrical and thermal conduction mechanisms in different organic electronic devices. FTIR microscopy was used to approach a realistic conduction mechanism by time-resolved chemical imaging of active materials in planar light-emitting electrochemical cells (LECs), investigated as an alternative to organic light emitting diodes (OLEDs). These chemical images are used for in-situ mapping of anion density profiles, polymer doping, and dynamic junction formation in the active layer under an applied bias. Results confirm the electrochemical doping model and help the systematic improvement of function and manufacture of LECs. Mixed ion-electron polymeric conductor materials such as PEDOT-PSS are used as active materials in organic thermoelectric generators (OTEGs), where charge carrier transport through the active layer promotes internal electrochemical reactions under a temperature gradient. FTIR microscopy and FTIR-attenuated total reflection (FTIR-ATR) were used to study thermoelectric and electrical properties of the conducting polymers. Recently, electrochemical supercapacitors have emerged as an alternative to conventional batteries, and polymeric materials are used to design polymer electrodes for renewable energy storage. To understand the charge transfer and structural changes of the polymer during the redox reaction, we have used FTIR-ATR as a tool for the in-situ spectroelectrochemical study of redox states in polypyrrole/lignin composites; we clarified the structural changes in the materials during charging and discharging of the composite. In further work, FTIR-ATR was also used for in-situ spectroelectrochemical studies of PEDOT:Cl, to monitor the effects of dissolved oxygen on PEDOT:Cl films, which are used as electrodes in renewable energy technologies. Further, time-resolved oxygen reduction reactions of PEDOT:Cl have been studied via polarization-modulation infrared reflection-absorption spectroscopy (PM-IRAS) to reveal chemical changes in electrochemically doped PEDOT upon exposure to oxygen.Taken together, these studies provide an advancement in the use of infrared spectroscopy as a tool to understand electroactive materials under wet conditions, and have provided detailed chemical and electrochemical information of materials and devices under operation, that is not easily accessible with other methods.
  •  
32.
  • Jafari, Mohammad Javad, et al. (författare)
  • Time-Resolved Chemical Mapping in Light-Emitting Electrochemical Cells
  • 2017
  • Ingår i: ACS Applied Materials and Interfaces. - : AMER CHEMICAL SOC. - 1944-8244 .- 1944-8252. ; 9:3, s. 2747-2757
  • Tidskriftsartikel (refereegranskat)abstract
    • An understanding of the doping and ion distributions in light-emitting electrochemical cells (LECs) is required to approach a realistic conduction model which can precisely explain the electrochemical reactions, p-n junction formation, and ion dynamics in the active layer and to provide relevant information about LECs for systematic improvement of function and manufacture. Here, Fourier-transform infrared (FTIR) microscopy is used to monitor anion density profile and polymer structure in situ and for time-resolved mapping of electrochemical doping in an LEC under bias. The results are in very good agreement with the electrochemical doping model with respect to ion redistribution and formation of a dynamic p-n junction in the active layer. We also physically slow ions by decreasing the working temperature and study frozen-junction formation and immobilization of ions in a fixed-junction LEC device by FTIR imaging. The obtained results show irreversibility of the ion redistribution and polymer doping in a fixed-junction device. In addition, we demonstrate that infrared microscopy is a useful tool for in situ characterization of electroactive organic materials.
  •  
33.
  • Jiao, Fei, et al. (författare)
  • Nanofibrillated Cellulose-Based Electrolyte and Electrode for Paper-Based Supercapacitors
  • 2018
  • Ingår i: ADVANCED SUSTAINABLE SYSTEMS. - : Wiley. - 2366-7486. ; 2:1
  • Tidskriftsartikel (refereegranskat)abstract
    • Solar photovoltaic technologies could fully deploy and impact the energy conversion systems in our society if mass-produced energy-storage solutions exist. A supercapacitor can regulate the fluctuations on the electrical grid on short time scales. Their mass-implementation requires the use of abundant materials, biological and organic synthetic materials are attractive because of atomic element abundancy and low-temperature synthetic processes. Nanofibrillated cellulose (NFC) coming from the forest industry is exploited as a three-dimensional template to control the transport of ions in an electrolyte-separator, with nanochannels filled of aqueous electrolyte. The nanochannels are defined by voids in the nanocomposite made of NFC and the proton transporting polymer polystyrene sulfonic acid PSSH. The ionic conductivity of NFC-PSSH composites (0.2 S cm(-1) at 100% relative humidity) exceeds sea water in a material that is solid, feel dry to the finger, but filled of nanodomains of water. A paper-based supercapacitor made of NFC-PSSH electrolyte-separator sandwiched between two paper-based electrodes is demonstrated. Although modest specific capacitance (81.3 F g(-1)), power density (2040 W kg(-1)) and energy density (1016 Wh kg(-1)), this is the first conceptual demonstration of a supercapacitor based on cellulose in each part of the device; which motivates the search for using paper manufacturing as mass-production of energy-storage devices.
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34.
  • Kawahara, Jun, et al. (författare)
  • Improving the color switch contrast in PEDOT:PSS-based electrochromic displays
  • 2012
  • Ingår i: Organic electronics. - : Elsevier BV. - 1566-1199 .- 1878-5530. ; 13:3, s. 469-474
  • Tidskriftsartikel (refereegranskat)abstract
    • Poly(3,4-ethylenedioxythiophene) chemically doped with poly(styrene sulfonic acid) (PEDOT:PSS) is a material system commonly used as a conductive and transparent coating in several important electronic applications. The material is also electrochemically active and exhibits electrochromic (EC) properties making it suitable as the active element in EC display applications. In this work uniformly coated PEDOT:PSS layers were used both as the pixel electrode and as the counter electrode in EC display components. The pixel and counter electrodes were separated by a whitish opaque and water-based polyelectrolyte and the thicknesses of the two EC layers were varied independently in order to optimize the color contrast of the display element. A color contrast (ΔE∗, CIE L∗a∗b∗ color space) exceeding 40 was obtained with maintained relatively short switching time at an operational voltage less than 2V.
  •  
35.
  • Khan, Zia Ullah, et al. (författare)
  • Nanofibrillated cellulose aerogels functionalized with conducting polymers for thermoelectric and dual-sensing applications
  • 2015
  • Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
    • Large amount of heat is wasted in industries, power generation plants and ordinary household appliances. This waste heat, can be a useful input to a thermoelectric generator (TEG) that can convert it to electricity. Conducting polymers (CPs) have been proved as best suited thermoelectric (TE) materials for lower temperatures, being not toxic, abundant in nature and solution processible. So far, CPs have been characterized as thin films, but it needs the third dimension to realize vertical TEGs which is possible by coating it on low thermal conductivity 3D skeletons. In this work, porous bulk cellulose structures have been used as a supporting material and were coated with CPs in various ways. The blend of cellulose and polymer were also freeze-dried, resulting in conducting and soft composites. Those flexible aerogels were utilized as a dual parameter sensor to sense pressure and temperature, based on the concept of thermoelectricity. It opens another application area of sensing, utilizing the thermoelectric phenomenon beyond the prevailing power generation concept. The sensitivity of such materials can be enhanced to make them useful as electronic skin in healthcare and robotics.
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36.
  • Laiho, Ari, et al. (författare)
  • Amphiphilic Poly(3-hexylthiophene)-Based Semiconducting Copolymers for Printing of Polyelectrolyte-Gated Organic Field-Effect Transistors
  • 2013
  • Ingår i: Macromolecules. - : American Chemical Society (ACS). - 0024-9297 .- 1520-5835. ; 46:11, s. 4548-4557
  • Tidskriftsartikel (refereegranskat)abstract
    • Polyelectrolytes are promising electronically insulating layers for low-voltage organic field effect transistors. However, the polyelectrolyte–semiconductor interface is difficult to manufacture due to challenges in wettability. We introduce an amphiphilic semiconducting copolymer which, when spread as a thin film, can change its surface from hydrophobic to hydrophilic upon exposure to water. This peculiar wettability is exploited in the fabrication of polyelectrolyte-gated field-effect transistors operating below 0.5 V. The prepared amphiphilic semiconducting copolymer is based on a hydrophobic regioregular poly(3-hexylthiophene) (P3HT) covalently linked to a hydrophilic poly(sulfonated)-based random block. Such a copolymer is obtained in a three-step strategy combining Grignard metathesis (GRIM), atom transfer radical polymerization (ATRP) processes, and a postmodification method. The structure of the diblock copolymer was characterized using FT-IR, 1H NMR spectroscopy, and gel permeation chromatography (GPC).
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37.
  • Lay, Makara, et al. (författare)
  • Direct Ink Writing of Nanocellulose and PEDOT:PSS for Flexible Electronic Patterned and Supercapacitor Papers
  • 2023
  • Ingår i: Advanced Materials Technologies. - : WILEY. - 2365-709X. ; 8:18
  • Tidskriftsartikel (refereegranskat)abstract
    • Printed electronic paper identifies its interest in flexible organic electronics and sustainable and clean energy applications because of its straightforward production method, cost-effectiveness, and positive environmental impact. However, current limitations include restricted material thickness and the use of supporting substrate for printing. Here, 2D and 3D electronic patterned paper are fabricated from direct ink writing (DIW) nanocellulose and PEDOT:PSS-based materials using syringe deposition and 3D printing. The conductor patterns are integrated in the bulk of the paper, while non-conductive sections are used as support to form free-standing paper. The strong interface between the patterns of electronic patterned paper gives mechanical stability for practical handling. The conductive paper-based electrode has 202 S cm(-1) and is capable of handling electric current up to 0.7 A, which can be used for high-power devices. Printed supercapacitor papers show high specific energy of 4.05 Wh kg(-1), specific power of 4615 W kg(-1) at 0.06 A g(-1), and capacitance retention above 95% after 2000 cycles. The new design structure of electronic patterned papers presents a solution for additive manufacturing of paper-based composites for supercapacitors, wearable electronics, or sensors for smart packaging.
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38.
  • Lestelius, Magnus, et al. (författare)
  • Order/disorder gradients of n-alkanethiols on gold
  • 1999
  • Ingår i: Colloids and Surfaces B. - : Elsevier. - 0927-7765 .- 1873-4367. ; 15:1, s. 57-70
  • Tidskriftsartikel (refereegranskat)abstract
    • This paper explores the interfacial properties of one-dimensional molecular gradients of alkanethiols (HS-(CH2)(n)- X) on gold. The kinetics and thermodynamics of monolayer formation are important issues for these types of mixed molecular assemblies. The influence of chain length difference on the contact angles with hexadecane (HD), theta(a) and theta(r), and the hysteresis, has been studied by employing alkanethiols HS-(CH2)(n)-CH3, with n = 9, 11, 13, 15 and 17, in the preparation of the self-assembled monolayers (SAM) gradients. The contact angles with hexadecane, at the very extreme ends of the gradients, show characteristic values of a highly ordered CH3-like assembly: theta(a) = 45-50 degrees. In the middle of the gradients theta(a) drops noticeably and exhibits values representative for CH2-like polymethylenes, theta(a) = 20-30 degrees, indicating a substantial disordering of the protruding chains of the longer component in the gradient assembly. As expected, the exposure of CH2-groups to the probing liquid increases with increasing differential chain length of the two n-alkanethiol used, in this case eight methylene units. However, the contact angles always display a non-zero value which means that even at a chain length difference of eight methylene units there is a substantial exposure of methyl (CH3) groups to the probing liquid. With infrared reflection-absorption spectroscopy (IRAS) we have monitored the structural behavior of the polymethylene chains along the gradient. We find complementary evidence for disordered chains in the gradient region, and the IRAS results correlate well with the contact angle measurements. (C) 1999 Elsevier Science B.V. All rights reserved.
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39.
  • Liedberg, Bo, et al. (författare)
  • Self-assembly of alpha-functionalized terthiophenes on gold
  • 1997
  • Ingår i: JOURNAL OF PHYSICAL CHEMISTRY B. - : AMER CHEMICAL SOC. - 1089-5647 .- 1520-6106 .- 1520-5207. ; 101:31, s. 5951-5962
  • Tidskriftsartikel (refereegranskat)abstract
    • alpha-Functionalized terthiophenes containing disulfide (-S-T-3-H)(2) and alkanethiol (HS-(CH2)(11)-T-3-H) anchoring groups have been synthesized for direct immobilization onto gold. Monolayer structures of these compounds are prepared by spontaneous assembly from ethanol solutions on evaporated gold substrates and thoroughly characterized by ellipsometry, contact angle goniometry, infrared and X-ray photoelectron spectroscopy, and cyclic voltammetry. The two molecules coordinate to the gold substrate exclusively via the anchoring groups upon formation of gold-thiolate bonds. The kinetics of monolayer formation vary dramatically for the two compounds. The alkanethiol analogue assembles rapidly, within a few minutes, and forms a densely packed and highly organized monolayer, with the alkyl chains in an almost perfect all-trans conformation and the C-alpha-C-alpha axis of the alpha-T-3 units tilted about 14 degrees away from the surface normal. The assembly process is much slower for the disulfide, but an organized monolayer with an average alpha-T-3 chain tilt of about 33 degrees will eventually form when the assembly is allowed to equilibrate with a solution containing the disulfide for at least 1 day. Moreover, the two monolayer assemblies also display a remarkably different electrochemical, behavior. The heterogeneous electron-transfer rate at the disulfide-covered gold substrate is almost indistinguishable from that at bare gold, suggesting that the assembly contains a large number of easily accessible defects. An alternative mechanism for explaining the large electron-transfer rate involving electronic coupling via the conjugated pi-system of the alpha-T-3 units is also proposed. The electrochemical response is significantly reduced for the HS-(CH2)(11)-T-3-H assembly, but another type of defects, the so-called shallow defects originating from sparsely populated areas on the electrode surface, can be identified.
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40.
  • Liu, Jiang, et al. (författare)
  • Double-Gate Light-Emitting Electrochemical Transistor: Confining the Organic p-n Junction
  • 2013
  • Ingår i: Journal of the American Chemical Society. - : American Chemical Society. - 0002-7863 .- 1520-5126. ; 135:33, s. 12224-12227
  • Tidskriftsartikel (refereegranskat)abstract
    • In conventional light-emitting electrochemical cells (LECs), an off-centered p-n junction is one of the major drawbacks, as it leads to exciton quenching at one of the charge-injecting electrodes and results in performance instability. To combat this problem, we have developed a new device configuration, the double-gate light-emitting electrochemical transistor (DG-LECT), in which the location of the light-emitting p-n junction can be precisely defined via the position of the two gate terminals. Based on a planar LEC structure, two gate electrodes made from an electrochemically active conducting polymer are employed to predefine the p- and n-doped area of the light-emitting polymer. Thus, a p-n junction is formed in between the p-doped and n-doped regions. We demonstrate a homogeneous and centered p-n junction as well as other predefined junction patterns in these DG-LECT devices. Additionally, we report an electrical model that explains the operation of the DG-LECTs. The DG-LECT device provides a new tool to study the fundamental physics of LECs, as it dissects the key working process of LEC into decoupled p-doping, n-doping, and electroluminescence.
  •  
41.
  • Liu, Jiang, et al. (författare)
  • Half‐Gate Light‐Emitting Electrochemical Transistor to Achieve Centered Emissive Organic p‐n Junction
  • 2015
  • Ingår i: Organic electronics. - : Elsevier. - 1566-1199 .- 1878-5530. ; 18, s. 32-36
  • Tidskriftsartikel (refereegranskat)abstract
    • Conventional organic light-emitting electrochemical cells show promise for lighting applications but in many cases suffer from unbalanced electrochemical doping. A predominant p-doping over n-doping causes an off-centered emissive p-n junction, which leads to poor power-conversion efficiency. Here, we report a half-gate lightemitting electrochemical transistor (HGLECT), in which a ion-conductive gate made from poly(3,4-ethylenedioxythiophene)-poly-(styrenesulfonate) is employed to combat this problem. The gate material, covering half the channel, is used to enhance the ndoping in this part by employing an appropriate operation protocol. We demonstrate a centered light emission zone, closely following the geometry of the gate material. The HGLECT with centered emission profile is shown to be more efficient than the corresponding LEC without gate electrode, and its n-doping level is measured to be 15%.
  •  
42.
  • Liu, Jiang (författare)
  • Light-Emitting Electrochemical Transistors
  • 2014
  • Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
    • Since the discovery of conductive polymers in 1977, the implementation of organic conjugated materials in electronic applications has been of great interest in both industry and academia. The goal of organic electronics is to realize large-area, inexpensive and mechanically-flexible electronic applications.Organic light emitting diodes (OLEDs), as the first commercial product made from organic conjugated polymers, have successfully demonstrated that organic electronics can make possible a new generation of modern electronics. However, OLEDs are highly sensitive to materials selection and requires a complicated fabrication process. As a result, OLEDs are expensive to fabricate and are not suitable for low-cost printing or roll-to-roll process.This thesis studies an alternative to OLEDs: light-emitting electrochemical cells (LECs). The active materials in an LEC consist of a conjugated light-emitting polymer (LEP) and an electrolyte. Taking advantage of electrochemical doping of the LEP, an LEC features an in-situ formed emissive organic p-n junction which is easy to fabricate. We aim to control the electrochemical doping profile by employing a “gate” terminal on top of a conventional LEC, forming a lightemitting electrochemical transistor (LECT). We developed three generations of LECTs, in which the position of the light-emitting profile can be modified by the voltage applied at the gate electrode, as well as the geometry of the gate materials. Thus, one can use this structure to achieve a centered light-emitting zone to maximize the power-conversion efficiency. Alternatively, LECTs can be used for information display in a highly integrated system, as it combines the simultaneous modulation of photons and electrons.In addition, we use multiple LECs to construct reconfigurable circuits, based on the reversible electrochemical doping. We demonstrate an LEC-array where several different circuits can be created by forming diodes with different polarity at different locations. The thereby formed circuitry can be erased and turned into circuitry with other functionality. For example, the diodes of a digital AND gate can be re-programmed to form an analogue voltage limiter. These reprogrammable circuits are promising for fully-printed and large-area reconfigurable circuits with facile fabrication.
  •  
43.
  • Liu, Jiang, et al. (författare)
  • Organic Reprogrammable Circuits Based on Electrochemically-Formed Diodes
  • 2014
  • Ingår i: ACS Applied Materials and Interfaces. - : American Chemical Society (ACS). - 1944-8244 .- 1944-8252. ; 6:15, s. 13266-13270
  • Tidskriftsartikel (refereegranskat)abstract
    • To simplify the integration of organic electronics, we demonstrate a method for constructing reprogrammable circuits based on organic diodes. The organic p‐n junction diodes consisting of an organic polymers poly[2‐methoxy‐5‐(2‐ethylhexyloxy)‐1,4‐phenylenevinylene and an electrolyte were formed by electrochemical doping at 70 °C, and stabilized at ‐30 °C. The reversible electrochemical reaction allows for the in‐situ change of the polarity of the organic p‐n junction. By forming diodes with different polarity at different locations, several circuits can be created, such as, logic gates, voltage limiter and AC/DC converter. The as‐made circuitry can be erased and turned into circuitry with other functionality. For example, the diodes of an AND gate can be re‐programmed to form an OR gate. The reprogrammable circuits contain merely two core layers, electrodes and active material, which is promising for large‐area and fully‐printed reconfigurable circuits with facile fabrication.
  •  
44.
  • Liu, Jiang, et al. (författare)
  • Spatial Control of p-n Junction in an Organic Light-Emitting Electrochemical Transistor
  • 2012
  • Ingår i: Journal of the American Chemical Society. - : American Chemical Society. - 0002-7863 .- 1520-5126. ; 134:2, s. 901-904
  • Tidskriftsartikel (refereegranskat)abstract
    • Low-voltage-operating organic electrochemical light-emitting cells (LECs) and transistors (OECTs) can be realized in robust device architectures, thus enabling easy manufacturing of light sources using printing tools. In an LEC, the p-n junction, located within the organic semiconductor channel, constitutes the active light-emitting element. It is established and fixated through electrochemical p- and n-doping, which are governed by charge injection from the anode and cathode, respectively. In an OECT, the electrochemical doping level along the organic semiconducting channel is controlled via the gate electrode. Here we report the merger of these two devices: the light-emitting electrochemical transistor, in which the location of the emitting p-n junction and the current level between the anode and cathode are modulated via a gate electrode. Light emission occurs at 4 V, and the emission zone can be repeatedly moved back and forth within an interelectrode gap of 500 mu m by application of a 4 V gate bias. In transistor operation, the estimated on/off ratio ranges from 10 to 100 with a gate threshold voltage of -2.3 V and transconductance value between 1.4 and 3 mu S. This device structure opens for new experiments tunable light sources and LECs with added electronic functionality.
  •  
45.
  • Liu, Jiang, et al. (författare)
  • Vertical polyelectrolyte-gated organic field-effect transistors
  • 2010
  • Ingår i: Applied Physics Letters. - : American Institute of Physics. - 0003-6951 .- 1077-3118. ; 97, s. 103303-
  • Tidskriftsartikel (refereegranskat)abstract
    • Short-channel, vertically structured organic transistors with a polyelectrolyte as gate insulator are demonstrated. The devices are fabricated using low-resolution, self-aligned, and mask-free photolithography. Owing to the use of a polyelectrolyte, our vertical electrolyte-gated organic field-effect transistors (VEGOFETs), with channel lengths of 2.2 and 0.7 μm, operate at voltages below one volt. The VEGOFETs show clear saturation and switch on and off in 200 μs. A vertical geometry to achieve short-transistor channels and the use of an electrolyte makes these transistors promising candidates for printed logics and drivers with low operating voltage.
  •  
46.
  • Malti, Abdellah, et al. (författare)
  • An Organic Mixed Ion-Electron Conductor for Power Electronics
  • 2016
  • Ingår i: Advanced Science. - : Wiley-Blackwell. - 2198-3844. ; 3:2
  • Tidskriftsartikel (refereegranskat)abstract
    • A mixed ionic–electronic conductor based on nanofibrillated cellulose composited with poly(3,4-ethylene-dioxythio­phene):­poly(styrene-sulfonate) along with high boiling point solvents is demonstrated in bulky electrochemical devices. The high electronic and ionic conductivities of the resulting nanopaper are exploited in devices which exhibit record values for the charge storage capacitance (1F) in supercapacitors and transconductance (1S) in electrochemical transistors.
  •  
47.
  • Malti, Abdellah, et al. (författare)
  • Enabling organic power electronics with a cellulose nano-scaffold
  • 2015
  • Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
    • Exploiting the nanoscale properties of certain materials enables the creation of new materials with a unique set of properties. Here, we report on an electronic (and ionic) conducting paper based on cellulose nanofibrils (CNF) composited with poly(3,4-ethylene-dioxythiophene):poly(styrene-sulfonate) (PEDOT:PSS), which may be facilely processed into large three-dimensional geometries, while keeping unprecedented electronic and ionic conductivities of 140 S/cm and 20 mS/cm, respectively. This is achieved by cladding the CNF with PEDOT:PSS, and trapping an ion-transporting phase in the interstices between these nanofibrils. The unique properties of the resulting nanopaper composite have been used to demonstrate (electrochemical) transistors, supercapacitors and conductors resulting in exceptionally high device parameters, such as an associated transconductance, charge storage capacity and current level beyond 1 S, 1 F and 1 A, respectively.
  •  
48.
  • Mastantuoni, Gabriella G., et al. (författare)
  • In Situ Lignin Sulfonation for Highly Conductive Wood/Polypyrrole Porous Composites
  • 2023
  • Ingår i: Advanced Materials Interfaces. - : Wiley. - 2196-7350. ; 10:1
  • Tidskriftsartikel (refereegranskat)abstract
    • To address the rising need of sustainable solutions in electronic devices, the development of electronically conductive composites based on lightweight but mechanically strong wood structures is highly desirable. Here, a facile approach for the fabrication of highly conductive wood/polypyrrole composites through top-down modification of native lignin followed by polymerization of pyrrole in wood cell wall. By sodium sulfite treatment under neutral condition, sulfonated wood veneers with increased porosity but well-preserved cell wall structure containing native lignin and lignosulfonates are obtained. The wood structure has a content of sulfonic groups up to 343 µmol g−1 owing to in situ sulfonated lignin which facilitates subsequent oxidative polymerization of pyrrole, achieving a weight gain of polypyrrole as high as 35 wt%. The lignosulfonates in the wood structure act as dopant and stabilizer for the synthesized polypyrrole. The composite reaches a high conductivity of 186 S m−1 and a specific pseudocapacitance of 1.71 F cm−2 at the current density of 8.0 mA cm−2. These results indicate that tailoring the wood/polymer interface in the cell wall and activating the redox activity of native lignin by sulfonation are important strategies for the fabrication of porous and lightweight wood/conductive polymer composites with potential for sustainable energy applications. 
  •  
49.
  •  
50.
  • Mastantuoni, Gabriella G., et al. (författare)
  • Rationally designed conductive wood with mechanoresponsive electrical resistance
  • 2024
  • Ingår i: Composites. Part A, Applied science and manufacturing. - : Elsevier BV. - 1359-835X .- 1878-5840. ; 178
  • Tidskriftsartikel (refereegranskat)abstract
    • Porous cellular foams, combining lightweight, high strength, and compressibility, hold great promise in a wide range of advanced applications. Here, the native structure of pine wood was modified by in-situ lignin sulfonation and unidirectional freezing, resulting in an alveolate structure inside the wood cell wall with arrays of sub-100 nm channels. The obtained wood foam exhibited highly enhanced permeability while retaining the native cellular arrangement and high lignin and hemicellulose content. Such engineered cellular foam contributed to superior mechanical performance with compressive strength of 9 MPa and Young's modulus of 344 MPa in the longitudinal direction. The high porosity allowed homogeneous infiltration of conductive polymer PEDOT:PSS inside the wood cell wall. The resulting composite exhibited high conductivity, sponge-like compressibility and the ability to modulate electrical resistance in a reversible manner in the radial direction. This rationally designed conductive wood demonstrated potential in durable and ultrasensitive pressure-responsive devices and strain sensors.
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