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Nanocellulose-based membranes have attracted intense attention in bioelectronic devices due to their low cost, flexibility, biocompatibility, degradability, and sustainability. Herein, we demonstrate a flexible ionic diode using a cross-linked bipolar membrane fabricated from positively and negatively charged cellulose nanofibrils (CNFs). The rectified current originates from the asymmetric charge distribution, which can selectively determine the direction of ion transport inside the bipolar membrane. The mechanism of rectification was demonstrated by electrochemical impedance spectroscopy with voltage biases. The rectifying behavior of this kind of ionic diode was studied by using linear sweep voltammetry to obtain current-voltage characteristics and the time dependence of the current. In addition, the performance of cross-linked CNF diodes was investigated while changing parameters such as the thickness of the bipolar membranes, the scanning voltage range, and the scanning rate. A good long-term stability due to the high density cross-linking of the diode was shown in both current-voltage characteristics and the time dependence of current., Funding Agencies|Wallenberg Wood Science Center; VINNOVA (Digital Cellulose Centre); Knut and Alice Wallenberg Foundation (Wallenberg Wood Science Center)

Osmotic energy generated from the salinity gradient is a kind of clean and renewable energy source, where the ion-exchange membranes play a critical role in its operation. The nanofluidic technique is emerging to overcome the limitations of high resistance and low mass transport of traditional ion-exchange membranes and thus improve osmotic power conversion. However, the currently reported nanofluidic materials suffer from high cost and complicated fabrication processes, which limits their practical application. Here, we report low-cost nanocellulose membranes that can be facilely prepared by a chemical cross-linking approach. The obtained membranes exhibit excellent ion transport characteristics as high-performance nanofluidic osmotic power generators. The control of cross-linker dosage enables the simultaneous tunability of the surface charge density and size of nanofluidic channels created between the interwoven cellulose nanofibrils. The maximum osmotic power generated by the membrane is reached when the cross-linker weight content is 20 wt %. Furthermore, the cross-linked nanocellulose membranes exhibit long-term working stability in osmotic energy harvesting under a wide range of pH values (3.2-9.7). This nanocellulose membrane derived from green and sustainable natural materials demonstrates a promising potential for renewable osmotic energy harvesting., Funding Agencies|Digital Cellulose Center (Swedish Innovation Agency VINNOVA); Wallenberg Wood Science Center (Knut and Alice Wallenberg Foundation); Karl-Erik Onnesjo Foundation

The nature of mass transport in plants has recently inspired the development of low-cost and sustainable wood-based electronics. Herein, we report a wood electrochemical transistor (WECT) where all three electrodes are fully made of conductive wood (CW). The CW is prepared using a two-step strategy of wood delignification followed by wood amalgamation with a mixed electron-ion conducting polymer, poly(3,4-ethylenedioxythiophene)–polystyrene sulfonate (PEDOT:PSS). The modified wood has an electrical conductivity of up to 69 Sm−1 induced by the formation of PEDOT:PSS microstructures inside the wood 3D scaffold. CW is then used to fabricate the WECT, which is capable of modulating an electrical current in a porous and thick transistor channel (1 mm) with an on/off ratio of 50. The device shows a good response to gate voltage modulation and exhibits dynamic switching properties similar to those of an organic electrochemical transistor. This wood-based device and the proposed working principle demonstrate the possibility to incorporate active electronic functionality into the wood, suggesting different types of bio-based electronic devices., QC 20230713

The quest for eco-friendly materials with anticipated positive impact for sustainability is crucial to achieve the UN sustainable development goals. Classical strategies of composite materials can be applied on novel nanomaterials and green materials. Besides the actual technology and applications also processing and manufacturing methods should be further advanced to make entire technology concepts sustainable. Here, they show an efficient way to combine two low-cost materials, cellulose and zinc oxide (ZnO), to achieve novel functional and "green" materials via paper-making processes. While cellulose is the most abundant and cost-effective organic material extractable from nature. ZnO is cheap and known of its photocatalytic, antibacterial, and UV absorption properties. ZnO nanowires are grown directly onto cellulose fibers in water solutions and then dewatered in a process mimicking existing steps of large-scale papermaking technology. The ZnO NW paper exhibits excellent photo-conducting properties under simulated sunlight with good ON/OFF switching and long-term stability (90 minutes). It also acts as an efficient photocatalyst for hydrogen peroxide (H2O2) generation (5.7 x 10(-9) m s(-1)) with an envision the possibility of using it in buildings to enable large surfaces to spontaneously produce H2O2 at its outer surface. Such technology promise for fast degradation of microorganisms to suppress the spreading of diseases., Funding Agencies|Knut and Alice Wallenberg Foundation; VINNOVA (Digital Cellulose Center); Vetenskapradet [2016-05990]; Swedish Government Strategic Research Area in Materials Science on Functional Materials at Linkoeping University [2009-00971]; aForsk Foundation [17-433]

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.

Advances in organic electronics necessitates, ultrathin and miniaturized implantable energy storage modules. Here, an approach for the fabrication of on-chip, ultraflexible electrochemical capacitors is demonstrated. Two different electroactive conjugated polymers are utilized in a fabrication route that allows the patterning of finger electrodes for an ultraflexible energy storage technology. A strategy is demonstrated to realize supercapacitors with a total device thickness of 4 mu m, including substrate, polymer electrode, and electrolyte. Interdigitated 20 -finger electrodes from either Poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) or poly-thiophene functionalized with tetraethylene glycol side chains P(g42T-T), with 50 mu m or 90 mu m electrode spacings, are fabricated using a parylene peel off method, followed by electrolyte deposition. The miniaturized devices show 0.77 mF/cm2 areal capacitance for PEDOT:PSS and 0.06 mF/cm2 for P(g42T-T). Furthermore, the devices exhibit excellent mechanical durability, showing robust operational performance at a bending radius of 6.5 mm., Funding Agencies|Swedish foundation; Knut and Alice Wallenberg Foundation; Onnesjo foundation; European Research Council [834677]

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 mu mol 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., Funding Agencies|Wallenberg Wood Science Center - Knut and Alice Wallenberg Foundation

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., Funding Agencies|Vinnova for the Digital Cellulose Competence Center (DCC) [2016-05193]; Swedish Foundation for Strategic Research [GMT14-0058]; Wallenberg Wood Science Centre

Ultrathin devices are rapidly developing for skin-compatible medical applications and wearable electronics. Powering skin-interfaced electronics requires thin and lightweight energy storage devices, where solution-processing enables scalable fabrication. To attain such devices, a sequential deposition is employed to achieve all spray-coated symmetric microsupercapacitors (mu SCs) on ultrathin parylene C substrates, where both electrode and gel electrolyte are based on the cheap and abundant biopolymer, cellulose. The optimized spraying procedure allows an overall device thickness of approximate to 11 mu m to be obtained with a 40% active material volume fraction and a resulting volumetric capacitance of 7 F cm(-3). Long-term operation capability (90% of capacitance retention after 10(4) cycles) and mechanical robustness are achieved (1000 cycles, capacitance retention of 98%) under extreme bending (rolling) conditions. Finite element analysis is utilized to simulate stresses and strains in real-sized mu SCs under different bending conditions. Moreover, an organic electrochromic display is printed and powered with two serially connected mu-SCs as an example of a wearable, skin-integrated, fully organic electronic application., Funding Agencies|European Research Council (ERC) under the European Unions Horizon 2020 research and innovation programEuropean Research Council (ERC) [949191]; city council of Brno, Czech Republic

Low weight, small footprint, and high performances are essential requisites for the implementation of energy storage devices within consumer electronics. One way to achieve these goals is to increase the thickness of the active material layer. In this work, carbonized and graphitized rayon felt, a cellulose-derived material, is used as a three-dimensional current collector scaffold to enable the incorporation of large amount of active energy storage materials and ionic liquid-based gel electrolyte in the supercapacitor devices. PEDOT:PSS, alone or in combination with active carbon, has been used as the active material. Three-dimensional supercapacitors with high per unit area capacitance (more than 1.1 F/cm(2)) have been achieved owing to the loading of large amount of active material in the felt matrix. Areal energy density of more than 101 mu Wh/cm(2) and areal power density of more than 5.9 mW/cm(2) have been achieved for 0.8 V operating voltage at a current density of 1 mA/cm(2). A nanographite material was found to be beneficial in reducing the internal serial resistance of the supercapacitor to lower than 1.7 omega. Furthermore, it was shown that even after 2000 times cycling test, the devices could still retain its performance with at least 88% coulombic efficiency for all the devices. All the materials are readily available commercially, environmentally sustainable and the process can potentially be upscaled with industrial process., Funding Agencies|Knut och Alice Wallenbergs Stiftelse; Onnesjo foundation; Stiftelsenfor Strategisk Forskning; VINNOVA

The dimensions of the material serving as the channel in organic electrochemical transistors (OECTs) are important for the overall switching performance. Here, a laser ablation step is included in the OECT manufacturing process, in an attempt to shorten the channel length of the OECT. The source and drain electrodes are formed by laser ablation of a previously screen printed carbon-based rectangle, which in this study resulted in an average channel length equal to 25 mu m. All other processing steps rely on screen printing, allowing for large-area manufacturing of OECTs and OECT-based circuits on flexible substrates. This approach results in a manufacturing yield of 89%; 178 out of a total of 200 OECTs exhibited an ON/OFF ratio exceeding 1000 with a statistical mean value of 28 000 and reproducible switching performance. OECT-based circuits, here demonstrated by a logic inverter, provide a reasonably high voltage gain of 12. The results thus demonstrate another reliable OECT manufacturing process, based on the combination of laser ablation and screen printing., Funding Agencies|Swedish foundation for Strategic Research (Silicon-Organic Hybrid Autarkic Systems) [SE13-0045]; Knut and Alice Wallenberg Foundation; Swedish Government Strategic Research Area in Materials Science on Advanced Functional Materials at Linkoping University; European Union [825339, 964677]; onnesjo Foundation

Nanostructured wood veneer with added electroactive functionality combines structural and functional properties into eco-friendly, low-cost nanocomposites for electronics and energy technologies. Here, we report novel conducting polymer-impregnated wood veneer electrodes where the native lignin is preserved, but functionalized for redox activity and used as an active component. The resulting electrodes display a well-preserved structure, redox activity, and high conductivity. Wood samples were sodium sulfite-treated under neutral conditions at 165 degrees C, followed by the tailored distribution of PEDOT:PSS, not previously used for this purpose. The mild sulfite process introduces sulfonic acid groups inside the nanostructured cell wall, facilitating electrostatic interaction on a molecular level between the residual lignin and PEDOT. The electrodes exhibit a conductivity of up to 203 S m(-1) and a specific pseudo-capacitance of up to 38 mF cm(-2), with a capacitive contribution from PEDOT:PSS and a faradaic component originating from lignin. We also demonstrate an asymmetric wood pseudo-capacitor reaching a specific capacitance of 22.9 mF cm(-2) at 1.2 mA cm(-2) current density. This new wood composite design and preparation scheme will support the development of wood-based materials for use in electronics and energy storage., Funding Agencies|Wallenberg Wood Science Center (Knut and Alice Wallenberg Foundation); Karl-Erik Onnesjo Foundation; Treesearch, a collaboration platform for Swedish forest industrial research

Organic electronic circuits based on organic electrochemical transistors (OECTs) are attracting great attention due to their printability, flexibility, and low voltage operation. Inverters are the building blocks of digital logic circuits (e.g., NAND gates) and analog circuits (e.g., amplifiers). However, utilizing OECTs in electronic logic circuits is challenging due to the resulting low voltage gain and low output voltage levels. Hence, inverters capable of operating at relatively low supply voltages, yet offering high voltage gain and larger output voltage windows than the respective input voltage window are desired. Herein, inverters realized from poly(3,4-ethylenedioxythiophene):polystyrene sulfonate-based OECTs are designed and explored, resulting in logic inverters exhibiting high voltage gains, enlarged output voltage windows, and tunable switching points. The inverter designs are based on multiple screen-printed OECTs and a resistor ladder, where one OECT is the driving transistor while one or two additional OECTs are used as variable resistors in the resistor ladder. The inverters performances are investigated in terms of voltage gain, output voltage levels, and switching point. Inverters, operating at +/-2.5 V supply voltage and an input voltage window of 1 V, that can achieve an output voltage window with similar to 110% increment and a voltage gain up to 42 are demonstrated., Funding Agencies|Swedish foundation for Strategic Research (Silicon-Organic Hybrid Autarkic Systems)Swedish Foundation for Strategic Research [SE13-0045]; Knut and Alice Wallenberg Foundation (Wallenberg Wood Science Center); European UnionEuropean Commission [825339, 964677]; onnesjo Foundation

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 super capacitor electrodes using a combination of printing methods., Funding Agencies|Swedish Foundation for Strategic ResearchSwedish Foundation for Strategic Research [GMT14-0058]

Ion selective membranes are at the heart of energy conversion and harvesting, water treatment, and biotechnologies. The currently available membranes are mostly based on expensive and non-biodegradable polymers. Here, we report a cation-selective and low-cost membrane prepared from renewable nanocellulose and 1,2,3,4-butanetetracarboxylic acid which simultaneously serves as crosslinker and source of anionic surface groups. Charge density and structure of the membranes are studied. By using different degrees of crosslinking, simultaneous control over both the nanochannel structure and surface charge concentration is achieved, which in turn determines the resulting ion transport properties. Increasing negative charge concentration via higher crosslinker content, the obtained ion conductivity reaches up to 8 mS/cm (0.1 M KCl). Optimal ion selectivity, also influenced by the solution pH, is achieved at 20 wt% crosslinker addition (with ion conductivity of 1.6 mS/cm). As regular similar to 1.4 nm nanochannels were formed at this composition, nanofluidic contribution to ion transport is likely., Funding Agencies|Digital Cellulose Centre; Wallenberg Wood Science Center (Knut and Alice Wallenberg Foundation); Karl-Erik Onnesjo Foundation; Treesearch, a collaboration platform for Swedish forest industrial research

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., QC 20221114

QC 20221114

Printed paper-based electronics offers solutions to rising energy concerns by supplying flexible, environmentally friendly, low-cost infrastructure for portable and wearable electronics. Herein, we demonstrate a scalable spray-coating approach to fabricate tailored paper poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS)/cellulose nanofibril (CNF) electrodes for all-printed supercapacitors. Layer-by-layer spray deposition was used to achieve high-quality electrodes with optimized electrode thickness. The morphology of these electrodes was analyzed using advanced X-ray scattering methods, revealing that spray-coated electrodes have smaller agglomerations, resulting in a homogeneous film, ultimately suggesting a better electrode manufacturing method than drop-casting. The printed paper-based supercapacitors exhibit an areal capacitance of 9.1 mF/cm(2), which provides enough energy to power electrochromic indicators. The measured equivalent series resistance (ESR) is as low as 0.3 Omega, due to improved contact and homogeneous electrodes. In addition, a demonstrator in the form of a self-powered wearable wristband is shown, where a large-area (90 cm(2)) supercapacitor is integrated with a flexible solar cell and charged by ambient indoor light. This demonstration shows the tremendous potential for sequential coating/printing methods in the scaling up of printed wearables and self-sustaining systems., Funding Agencies|Swedish Foundation for Strategic Research; Knut and Alice Wallenberg Foundation (Wallenberg Wood Science Center); Onnesjo Foundation; EU SYMPHONY project (H2020) [862095]; DESY Strategic Fund (DSF)

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 mu mol 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., Funding Agencies|Wallenberg Wood Science Center - Knut and Alice Wallenberg Foundation

Nanostructured wood veneer with added electroactive functionality combines structural and functional properties into eco-friendly, low-cost nanocomposites for electronics and energy technologies. Here, we report novel conducting polymer-impregnated wood veneer electrodes where the native lignin is preserved, but functionalized for redox activity and used as an active component. The resulting electrodes display a well-preserved structure, redox activity, and high conductivity. Wood samples were sodium sulfite-treated under neutral conditions at 165 °C, followed by the tailored distribution of PEDOT:PSS, not previously used for this purpose. The mild sulfite process introduces sulfonic acid groups inside the nanostructured cell wall, facilitating electrostatic interaction on a molecular level between the residual lignin and PEDOT. The electrodes exhibit a conductivity of up to 203 S m−1 and a specific pseudo-capacitance of up to 38 mF cm−2, with a capacitive contribution from PEDOT:PSS and a faradaic component originating from lignin. We also demonstrate an asymmetric wood pseudo-capacitor reaching a specific capacitance of 22.9 mF cm−2 at 1.2 mA cm−2 current density. This new wood composite design and preparation scheme will support the development of wood-based materials for use in electronics and energy storage., QC 20230614

Osmotic energy generated from the salinity gradient is a kind of clean and renewable energy source, where the ion-exchange membranes play a critical role in its operation. The nanofluidic technique is emerging to overcome the limitations of high resistance and low mass transport of traditional ion-exchange membranes and thus improve osmotic power conversion. However, the currently reported nanofluidic materials suffer from high cost and complicated fabrication processes, which limits their practical application. Here, we report low-cost nanocellulose membranes that can be facilely prepared by a chemical cross-linking approach. The obtained membranes exhibit excellent ion transport characteristics as high-performance nanofluidic osmotic power generators. The control of cross-linker dosage enables the simultaneous tunability of the surface charge density and size of nanofluidic channels created between the interwoven cellulose nanofibrils. The maximum osmotic power generated by the membrane is reached when the cross-linker weight content is 20 wt %. Furthermore, the cross-linked nanocellulose membranes exhibit long-term working stability in osmotic energy harvesting under a wide range of pH values (3.2-9.7). This nanocellulose membrane derived from green and sustainable natural materials demonstrates a promising potential for renewable osmotic energy harvesting., Funding Agencies|Digital Cellulose Center (Swedish Innovation Agency VINNOVA); Wallenberg Wood Science Center (Knut and Alice Wallenberg Foundation); Karl-Erik Onnesjo Foundation

Low-voltage operating organic electronic circuits with long-term stability characteristics are receiving increasing attention because of the growing demands for power efficient electronics in Internet of Things applications. To realize such circuits, inverters, the fundamental constituents of many circuits, with stable transfer characteristics should be designed to provide low-power consumption. Here, a rational inverter design, based on fully screen printed p-type organic electrochemical transistors with a channel size of 150 x 80 mu m(2), is explored for driving conditions with input voltage levels that differs of about 1 V. Further, three different inverter circuits are explored, including resistor ladders with resistor values ranging from tens of k ohm to a few M ohm. The performance of single inverters, 3-stage cascaded inverters and 3-stage ring oscillators are characterized with respect to output voltage levels, propagation delay, static power consumption, voltage gain, and operational frequency window. Depending on the application, the key performance parameters of the inverter can be optimized by the specific combination of the input voltage levels and the resistor ladder values. A few of the inverters are in fact fully functional up to 30 Hz, even when using input voltage levels as low as (0 V, 1 V)., Funding Agencies|Swedish foundation for Strategic Research (Silicon-Organic Hybrid Autarkic Systems)Swedish Foundation for Strategic Research [SE13-0045]; Knut and Alice Wallenberg Foundation (Wallenberg Wood Science Center); European UnionEuropean Commission [825339]; onnesjo Foundation

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-Perot 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., Funding Agencies|Swedish Foundation for Strategic Research (SSF)Swedish Foundation for Strategic Research; Knut and Alice Wallenberg FoundationKnut & Alice Wallenberg Foundation; Swedish Research Council (VR)Swedish Research Council; Wenner-Gren Foundations; Swedish Government Strategic Research Area in Materials Science on Functional Materials at Linkoping University (Faculty Grant SFO-Mat-LiU) [2009 00971]

The ongoing electrification of many energy systems has created a large demand for low-cost and scalable electrical energy storage solutions. Conducting polymer supercapacitors have received significant attention for this purpose due to the abundance of their constituent materials. Although there exists a large body of experimental work on conducting polymer supercapacitors, a detailed understanding of the mixed electronic-ionic transport processes within these devices and the included materials, is still lacking. Modelling, in combination with experimental data, is a powerful tool to facilitate a detailed understanding of the transport processes within the materials and devices. However, to date, there has been a shortage of physical models which account for the non-ideal capacitances typically found in conducting polymer-based supercapacitors. Here, we report a novel model which reproduces experimental data and provides insights into the cyclic voltammograms, galvanostatic charge-discharge curves, self-discharge characteristics, and impedance spectroscopy results of supercapacitors based on the conducting polymer poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) and cellulose nanofibrils. We find that the non-ideal capacitive characteristics of the supercapacitors can be reproduced by the incorporation of heterogeneous ion transport features within the electrodes, comprising low ion diffusivity regions. The difference in charging rates of the high and low ion diffusivity regions accounts for the experimentally observed trends in cyclic voltammograms and self-discharge characteristics. The developed model demonstrates how complex transport processes, which govern the specifications of organic energy devices, can be analysed beyond the scope of conventional equivalent circuit models. It also provides an insight into how various transport and polarization processes are manifested in real measurement data and thus defines the limiting processes of co, Funding Agencies|Knut and Alice Wallenberg FoundationKnut & Alice Wallenberg Foundation; Linkoping University; Swedish Government Strategic Research Area in Materials Science on Advanced Functional Materials at Linkoping University (Faculty Grant SFO-Mat-LiU) [2009-00971]; Swedish Foundation for Strategic ResearchSwedish Foundation for Strategic Research; Wallenberg Wood Science Centre

Energy storage technology incorporating conducting polymers as the active component in electrode structures, in part based on natural materials, is a promising strategy toward a sustainable future. Electronic and ionic charge transport in poly(3,4-ethylenedioxythiophene) (PEDOT) provides fundamentals for energy storage, governed by volumetric PEDOT:counterion double layers. Despite extensive experimental investigations, a solid understanding of the capacitance in PEDOT-based nanocomposites remains unsatisfactory. Here, we report on the charge storage mechanism in PEDOT composited with cellulose nanofibrils (termed as "power paper") from three different perspectives: experimental measurements, density functional theory atomistic simulations, and device-scale simulations based on the NernstPlanck-Poisson equations. The capacitance of the power paper was investigated by varying the film thickness, charging currents, and electrolyte ion concentrations. We show that the volumetric capacitance of the power paper originates from electrostatic molecular double layers defined at atomistic scales, formed between holes, localized in the PEDOT backbone, and their counterions. Experimental galvanostatic cycling characteristics of the power paper is well reproduced within the electrostatic Nernst-PlanckPoisson model. The difference between the specific capacitance and the intrinsic volumetric capacitance is also outlined. Substantial oxygen reduction reactions were identified and recorded in situ in the vicinity of the power paper surface at negative potentials. Purging of dissolved oxygen from the electrolyte leads to the elimination of currents originating from the oxygen reduction reactions and allows us to obtain well-defined electrostatic-capacitive behavior (box-shaped cyclic voltammetry and triangular galvanostatic charge-discharge characteristics) at a large operational potential window from -0.6 V to +0.6 V. The obtained results reveal that the fundamental charge storage, Funding Agencies|Swedish Energy AgencySwedish Energy Agency [43561-1]; Wallenberg Wood Science Center

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/cm(2), and was explored as the back-electrode in printed electrochromic displays., Funding Agencies|Digital Cellulose Centre, a competence center set up by the Swedish Innovation Agency VINNOVA; consortium of Swedish forest industries; Wallenberg Wood Science Center (Knut and Alice Wallenberg Foundation); VINNOVA "EPIC" projectVinnova [2017-05413]; Karl-Erik Onnesjo Foundation

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., QC 20191007

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., Funding Agencies|Advanced Functional Materials Center at Linkoping University; Onnesjo Foundation; Knut and Alice Wallenberg FoundationKnut & Alice Wallenberg Foundation; Swedish Foundation for Strategic ResearchSwedish Foundation for Strategic Research; Aquitaine regionRegion Nouvelle-Aquitaine; Arkema; Equipex ELOR-PrintTec [ANR-10EQPX-28-01]; LabEx AMADEUS [ANR-10-LABEX0042-AMADEUS]; French state Initiative dExcellence IdEx [ANR-10-IDEX-003-02]; LCPO/Arkema INDUSTRIAL CHAIR HOMERIC [ANR-13CHIN-0002-01]

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 approximate to 90 F g(-1) and an excellent cyclability (amp;gt;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., Funding Agencies|Swedish Foundation for Strategic ResearchSwedish Foundation for Strategic Research [GMT14-0058]

The growth of renewable energy production has sparked a huge demand for cheap and large-scale electrical storage solutions. Organic supercapacitors and batteries are envisioned as one, among several, candidates for this task due to the great abundance of their constituent materials. In particular, the class of supercapacitors based on conjugated polymer-redox biopolymer composites are of great interest, since they combine the benefit of high electrical conductivity of the conducting polymers with the low cost and high specific capacitance of redox biopolymers. The optimization of such complex systems is a grand challenge and until now there have been a lack of models available to ease that task. Here, we present a novel model that combines the charge transport and impedance properties of conducting polymers with the electrochemical characteristics of redox polymers. The model reproduces a wide range of experimental data and elucidates the coupling of several critical processes within these supercapacitors, such as the double-layer capacitance, redox kinetics and dissolution/release of the redox polymer to the electrolyte. Further, the model also predicts the dependencies of the power and energy densities on the electrode composition. The developed model shows how organic supercapacitors can be analyzed beyond archetypical equivalent circuit models and thus constitutes a promising tool for further advancements and optimization within the field of research of green energy storage technology., Funding Agencies|Knut and Alice Wallenberg foundationKnut & Alice Wallenberg Foundation; Linkoping University; Wallenberg Wood Science Center; Swedish Government Strategic Research Area in Materials Science on Advanced Functional Materials at Linkoping University [2009-00971]; Swedish Foundation for Strategic ResearchSwedish Foundation for Strategic Research

The conducive polymer poly(3,4-ethylenedioxythiphene):poly(styrenesulfonate) (PEDOT:PSS) is widely used in organic electronics and printed electronics due to its excellent electronic and ionic conductivity. PEDOT:PSS films exhibit anisotropic conductivities originating from the interplay of film deposition processes and chemical structure. The previous studies found that high boiling point solvent treated PEDOT:PSS exhibits an anisotropy of 3-4 orders magnitude. Even though both the in-plane and out-of-plane conductivities are important for the device performance, the out-of-plane conductivity is rarely studied due to the complexity with the experiment procedure. Cellulose-based paper or films can also exhibit anisotropic behavior due to the combination of their intrinsic fibric structure and film formation process. We have previously developed a conducive paper based on PEDOT:PSS and cellulose which could be used as the electrodes in energy storage devices. In this work we developed a novel measurement set-up for studying the anisotropy of the charge transport in such composite materials. A tool with two parallel plates mounted with spring loaded probes was constructed enabling probing both lateral and vertical directions and resistances from in-plane and out-of-plane directions to be obtained. The measurement results were then input and analyzed with a model based on a transformation method developed by Montgomery, and thus the in-plane and out-of-plane conductivities could be detangled and derived. We also investigated how the conductivity anisotropy depends on the microstructure of the cellulose template onto which the conducive polymer self-organizes. We show that there is a relatively small difference between the in-plane and out-of-plane conductivities which is attributed to the unique 3D-structure of the composites. This new knowledge gives a better understanding of the possibilities and limitations for using the material in electronic and electrochemical de, Funding Agencies|Swedish Foundation for Strategic Research [GMT14-0058]

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., Funding Agencies|Swedish Foundation for Strategic ResearchSwedish Foundation for Strategic Research [GMT14-0058]; Knut and Alice Wallenberg FoundationKnut & Alice Wallenberg Foundation; Strategic Research Area (SFO) for Advanced Functional Materials at LiU; Onnesjo Foundation; Swedish Research CouncilSwedish Research Council; VINNOVAVinnova

State-of-the-art solar energy harvesting systems based on photovoltaic technology require constant illumination for optimal operation. However, weather conditions and solar illumination tend to fluctuate. Here, a device is presented that extracts electrical energy from such light fluctuations. The concept combines light-induced heating of gold nanodisks (acting as plasmonic optical nanoantennas), and an organic pyroelectric copolymer film (poly(vinylidenefluoride-co-trifluoroethylene)), that converts temperature changes into electrical signals. This hybrid device can repeatedly generate current pulses, not only upon the onset of illumination, but also when illumination is blocked. Detailed characterization highlights the key role of the polarization state of the copolymer, while the copolymer thickness has minor influence on performance. The results are fully consistent with plasmon-assisted pyroelectric effects, as corroborated by combined optical and thermal simulations that match the experimental results. Owing to the tunability of plasmonic resonances, the presented concept is compatible with harvesting near infrared light while concurrently maintaining visible transparency., Funding agencies: Wenner-Gren Foundations; Swedish Research Council [2015-05070]; Swedish Foundation for Strategic Research; AForsk Foundation; Royal Swedish Academy of Sciences; Swedish Government Strategic Research Area in Materials Science on Functional Materials at Lin

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., Funding Agencies|Knut and Alice Wallenberg foundation [KAW 2011.0050]; Swedish Foundation for Strategic Research [GMT14-0058]; Onnesjo Foundation; Swedish Energy Agency; Advanced Functional Materials Center at Linkoping University

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., Funding Agencies|European Research Council [307596]; Advanced Functional Materials Center at Linkoping University