Organic polymer thermoelectrics (TE) as well as transition metal (TM) silicides are two thermoelectric class of materials of interest because they are composed of atomic elements of high abundance; which is a prerequisite for mass implementation of thermoelectric (TE) solutions for solar and waste heat recovery. But both materials have drawbacks when it comes to finding low-cost manufacturing. The metal silicide needs high temperature (>1000 °C) for creating TE legs in a device from solid powder, but it is easy to achieve long TE legs in this case. On the contrary, organic TEs are synthesized at low temperature from solution. However, it is difficult to form long legs or thick films because of their low solubility. In this work, we propose a novel method for the room temperature synthesis of TE composite containing the microparticles of chromium disilicide; CrSi2 (inorganic filler) in an organic matrix of nanofibrillated cellulose- poly(3,4-ethyelenedioxythiophene)-polystyrene sulfonate (NFC-PEDOT:PSS). With this method, it is easy to create long TE legs in a room temperature process. The originality of the approach is the use of conducting polymer aerogel microparticles mixed with CrSi2 microparticles to obtain a composite solid at room temperature under pressure. We foresee that the method can be scaled up to fabricate and pattern TE modules. The composite has an electrical conductivity (σ) of 5.4 ± 0.5 S/cm and the Seebeck coefficient (α) of 88 ± 9 ΌV/K, power factor (α2σ) of 4 ± 1 ΌWm−1K−2 at room temperature. At a temperature difference of 32 °C, the output power/unit area drawn across the load, with the resistance same as the internal resistance of the device is 0.6 ± 0.1 ΌW/cm2.

An environmentally benign synthesis of a magnetically responsive carboxymethylated cellulose nanofibril-based material is reported. Applied experimental conditions lead to the in-situ formation of magnetite nanoparticles with primary particle sizes of 2.0–4.0 nm or secondary particles of 3.6–16.4 nm depending on whether nucleation occurred between individual carboxymethylated cellulose nanofibrils, or on exposed fibril surfaces. The increase in magnetite particle size on the cellulose fibril surfaces was attributed to Ostwald ripening, while the small particles formed within the carboxymethyl cellulose aggregates were presumably due to steric interactions. The magnetite nanoparticles were capable of coordinating to carboxymethylated cellulose nanofibrils to form large “fibre-like” assemblies. The confinement of small particles within aggregates of reductive cellulose molecules was most likely responsible for excellent conservation of magnetic characteristics on storage of this material. The possibility for using the material in drug delivery applications with release rate controlled by daylight illumination is presented. © 2022 The Author(s)

Taking ideas to market can be a long, iterative, and complex process. When dealing with new bio-based materials, under-standing factors that help bridge the lab-to-market gap and how materials are selected for new product development have the potential to speed up the transition to a circular bioeconomy. This article defines abstract and conceptual material demonstrators and explores how they support the innovation process in different ways. Nine roles are iden-tified, including how material demonstrators contribute to generating and expressing new ideas, enable a shared understanding of technology, support the discovery of market value and the visualization of potential applications as well as helping to articulate internal and external strategies and communications. Abstract and conceptual material dem-onstrators are exemplified with both technology-driven and market-driven bio-based materials used in packaging.

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.

Wereport 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. Wealso 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.Wehave further used these devices to construct digital circuits such as NOT, NANDandNORlogic.

Chemically cross-linked highly porous nanocellulose aerogels with complex shapes have been prepared using a freeze-linking procedure that avoids common post activation of cross-linking reactions and freeze-drying. The aerogel shapes ranged from simple geometrical three-dimensional bodies to swirls and solenoids. This was achieved by molding or extruding a periodate oxidized cellulose nanofibril (CNF) dispersion prior to chemical cross-linking in a regular freezer or by reshaping an already prepared aerogel by plasticizing the structure in water followed by reshaping and locking the aerogel into its new shape. The new shapes were most likely retained by new cross-links formed between CNFs brought into contact by the deformation during reshaping. This self-healing ability to form new bonds after plasticization and redrying also contributed to the mechanical resilience of the aerogels, allowing them to be cyclically deformed in the dry state, reswollen with water, and redried with good retention of mechanical integrity. Furthermore, by exploiting the shapeability and available inner structure of the aerogels, a solenoid-shaped aerogel with all surfaces coated with a thin film of conducting polypyrrole was able to produce a magnetic field inside the solenoid, demonstrating electromagnetic properties. Furthermore, by biomimicking the porous interior and stiff exterior of the beak of a toucan bird, a functionalized aerogel was created by applying a 300 μm thick stiff wax coating on its molded external surfaces. This composite material displayed a 10-times higher elastic modulus compared to that of the plain aerogel without drastically increasing the density. These examples show that it is possible to combine advanced shaping with functionalization of both the inner structure and the surface of the aerogels, radically extending the possible use of CNF aerogels.

Chemically cross-linked, wet-stable cellulose nanofibril (CNF) aerogel beads were fabricated using a novel procedure. The procedure facilitated controlled production of millimetre-sized CNF aerogel beads without freeze-drying or critical point drying, while still retaining a highly porous structure with low density. The aerogel beads were mechanically robust in the dry state, supporting loads of 1.3 N at 70% compression, even after being soaked in water and re-dried. Furthermore, they displayed both a good stability in water and a remarkably good shape recovery after wet compression. Owing to the stability in water, the entire surface of the highly porous aerogel beads could be successfully functionalized with polyelectrolytes and carboxyl-functionalized single-wall carbon nanotubes (CF-SWCNTs) using the Layer-by-Layer technique, introducing a significant electrical conductivity (1.6 mS/cm) to the aerogel beads. The functionalized, electrically conducting aerogel beads could carry as much as 2 kA/cm2 and act as electrodes in a supercapacitor displaying a stabilized charge storage capacity of 9.8 F/g after 50 charging–discharging cycles.

The underlying mechanism related to freezing-induced crosslinking of aldehyde-containing cellulose nanofibrils (CNFs) has been investigated, and the critical parameters behind this process have been identified. The aldehydes introduced by periodate oxidation allows for formation of hemiacetal bonds between the CNFs provided the fibrils are in sufficiently close contact before the water is removed. This is achieved during the freezing process where the cellulose components are initially separated, and the growth of ice crystals forces the CNFs to come into contact in the thin lamellae between the ice crystals. The crosslinked 3-D structure of the CNFs can subsequently be dried under ambient conditions after solvent exchange and still maintain a remarkably low density of 35 kg m-3, i.e. a porosity greater than 98%. A lower critical amount of aldehydes, 0.6 mmol g-1, was found necessary in order to generate a crosslinked 3-D CNF structure of sufficient strength not to collapse during the ambient drying. The chemical stability of the 3-D structure can be further enhanced by converting the hemiacetals to acetals by treatment with an alcohol under acidic conditions.

Research in smart textiles is growing due to the increased demand from the healthcare sector and people's urge to keep track of and analyze the signals and metrics from their bodies. Electrically conductive filaments are the most fundamental material for smart textiles. These filaments can be imbued with functionalities and useful in fields like energy storage, sensing, and actuation. To be able to meet the requirements that the latter applications require, fabrication techniques must be developed to provide better processability and sustainability in a cost-effective manner. Here, a mixture of a conductive polymer, poly(3,4-ethylenedioxythiophene) (PEDOT), and biobased cellulose nanofibrils (CNFs) was used to spin filaments utilizing a water-based process. These filaments show electrical conductivities up to 150 S/cm and tensile stiffness of 20 GPa. Interestingly, the PEDOT aligned to a similar degree as the CNFs during the spinning process without a drawing step, which is hypothesized to be caused by the attachment of PEDOT on the CNFs. Lastly, the filaments were tested in an organic electrochemical transistor (OECT) configuration, which resulted in a working device with an on/off ratio approaching 1500. Furthermore, the OECT exhibited stable behavior when changing temperature (20-80 °C) and relative humidity (40-80%). This aqueous spinning method, resulting in filaments with robust electronic properties in different temperature and humidity environments, show greats promise for future innovative smart textiles.

This study presents a novel, green, and efficient way of preparing crosslinked aerogels from cellulose nanofibers (CNFs) and alginate using non-covalent chemistry. This new process can ultimately facilitate the fast, continuous, and large-scale production of porous, light-weight materials as it does not require freeze-drying, supercritical CO2 drying, or any environmentally harmful crosslinking chemistries. The reported preparation procedure relies solely on the successive freezing, solvent-exchange, and ambient drying of composite CNF-alginate gels. The presented findings suggest that a highly-porous structure can be preserved throughout the process by simply controlling the ionic strength of the gel. Aerogels with tunable densities (23–38 kg m−3) and compressive moduli (97–275 kPa) can be prepared by using different CNF concentrations. These low-density networks have a unique combination of formability (using molding or 3D-printing) and wet-stability (when ion exchanged to calcium ions). To demonstrate their use in advanced wet applications, the printed aerogels are functionalized with very high loadings of conducting poly(3,4-ethylenedioxythiophene):tosylate (PEDOT:TOS) polymer by using a novel in situ polymerization approach. In-depth material characterization reveals that these aerogels have the potential to be used in not only energy storage applications (specific capacitance of 78 F g−1), but also as mechanical-strain and humidity sensors. © 2020 The Authors. 

Graphite materials show high electrical and thermal conductivity making them useful in electronics both as electrical conductor, but as of today primarily used as a thermal conductor for thermal management and as the dominating anode material in lithium ion batteries. The conductivities depend on for example the degree of graphitisation, that is how close the material is to perfect graphite. Graphite materials can occur naturally in the earth’s bedrock and can thus be extracted by mining and is then called natural graphite. Graphitic carbon materials can also be synthesised and are then usually referred to a synthetic or artificial graphite, even though they should be referred to as graphite materials if being strict, as they never reach the structure of perfect graphite and always contain some defects and irregularities. This report starts with a short description of all carbon allotropes, i.e. structurally different forms of the same element due to how the atoms are chemically bonded to each other. It then continues with an overview of how graphitic carbon materials can and should be characterised, as well as analytical methods for making this characterisation. After this a section on production methods for graphite materials follows, that dependent on the principles they operate by are divided into: • Mining for graphite that occurs naturally in the earth’s bedrock. • High temperature heat-treatment, so called carbonisation, hydrothermal carbonisation if done in water, and graphitisation. • Chemical vapour deposition, i.e. depositing molecules or atoms in gas phase on a solid surface, that is used to synthesise pyrolytic carbon and graphite. • Extraction from a steelmaking by-product called Kish to obtain so called Kish graphite. • Thermal decomposition of carbides. This is followed by a section on the today most common and important graphite materials, which are: natural graphite (mined), anisotropic synthetic graphite, isotropic synthetic graphite, pyrolytic carbon and graphite. This section also includes specific production process details for the above listed graphite materials, their main properties, advantages, and common uses. Two of the most common and important uses of graphite materials, i.e. as anode in lithium ion batteries and for thermal management in electronics, are described somewhat more in depth. The focus of this report is biomass derived graphitic materials and this focus start fully first in section number four, which compares published values on electrical and thermal conductivity of different fossil and bio-based graphitic carbon materials. This comparison clearly shows that it is very challenging to derive graphitic carbon materials with high conductivities from biomass. This is because essentially all biomass is so-called non-graphitising or hard carbon precursor meaning that it is not transformed into highly graphitic carbon no matter how high temperature it is heated to. Catalytic graphitisation using metals salts or oxides can increase the degree of graphitisation that can be achieved, but all substances used for catalysing graphitisation forms solid nanoparticles which leaves voids when removed by for example acid dissolution, making the resulting graphitic material porous which in turn limits its electrical and thermal conductivity. Of all production processes reviewed here to create highly electrically and thermally conductive graphitic carbon materials from biomass, requiring a high degree of graphitisation and dense material, two methods stand out as especially interesting: • Chemical vapour deposition on suitable substrate (carbon materials, metals or ceramics) using biomass as carbon source. • Resistive heating of biomass derived films/objects. Bio-based free-standing graphene film with very high electrical and thermal conductivity have been produced using chemical vapour deposition technique. From a practical handling perspective, it would be beneficial to create thicker highly graphitic carbon films to make them stronger, although it may reduce the conductivities of the material. Methods based on chemical vapour deposition may be improved to be able to produce thicker graphitic films. Resistive heating of a film made of e.g. biobased lignin, mixed with mined graphene to 2192 °C have been shown to create a highly graphitic carbon film with the excellent electrical conductivity of 4480 S/cm. By substituting the mined graphene to bio-based ditto may open up for the production of a fully biobased, highly graphitic film with excellent conductive properties. It is suggested that the way to achieve fully biobased highly graphitic and dense films is to further refine the chemical vapour deposition and the resistive heating method.

Matching market demands and technological solutions is not always straightforward. In this article, we report on one material, a cellulose-PLA multimaterial, which was made on a full-scale pilot paper machine and adapted to five different market applications having specialized and often conflicting demands. The material can be injection molded, 3D-printed, hot pressed, treated as a textile, used in a laminate, or converted as a paper board, giving it a wide range of possible properties depending on how it is processed.The five application areas presented here were identified as gaps in the marketplace where seemingly conflicting needs were desired: opacity and transparency; compact for transport but having an expanded size during use; stiffness and flexibility; strength and light-weight; and durability and degradability. These properties are exemplified in a number of material and product demonstrators, illustrating how tailored solutions can give products with distinctly different personalities. The material can be made flexible and given movement as graceful as the wing of a bird or be processed to be strong and light-weight enough to be used in vehicles like airplanes. By having one material that is produced on a large scale, but then processed according to specific market demands and expectations, the gap between needing scale and needing scope is bridged.

Recent findings have shown that it is possible to use the Layer-by-Layer technique to create nanofibrillated cellulose / polyethyleneimine interference films whose colour change with relative humidity. This study uses different optical models to describe spectral ellipsometry measurements data of interference films and how the film properties alter in dry and humid environments. The results indicate that water condensation initially is filling the surface pores within seconds whereas relaxation of the film to adjust to the added water is a slower process that reaches a steady state after ~20 min. The maximum swelling ratio of the LbL films is almost independent of the number of layers within the film, but decreases considerably by crosslinking via heat treatment. The films show a distinct birefringence with optical axis perpendicular to the surface. Analysis of the moisture response with different optical models indicates that the films swell uniformly in the thickness direction with no separate water film on top. The results provide important understanding for the design of NFC based LbL films for visual moisture sensors and interactive security paper.

Research has been undertaken into the mixing of electroactive additives (EAA), for example, conducting polymers or particles, in five different cellulose structures and their further processing into electroactive papers and films. The cellulose structures considered included cellulose nanofibrils (CNF) hydrogels, CNG aerogels, CNF filaments, CNF films and cellulose papers. It has been demonstrated that the cellulose structure in combination with the electroactive polymer or particle, could be used to tailor numerous different properties. The cellulose could provide properties that support structural integrity, processability, ionic conductivity, shapeability and a large inner capacitive surface. The highly porous aerogel particles could be shaped using three-dimensional printed templates prior to freezing. The particles could be filled either with active material from the start before freeze-linking or filled with active material afterwards based on the layer by layer method. Electroactive paper could also be produced by adding the active component directly as a filler during papermaking, by adding CNF spun EA filaments cut into conveniently long staple fibres.

A study has been made of the production of zinc oxide (ZnO) paper in a pilot paper machine. Bleached sulphate softwood pulp (70%) and bleached sulphate hardwood pulp (30%) were corefined. Cationic polyacrylamide (CPAM) was used as retention agent, while alkyl ketene dimer (AKD) was used as sizing agent for some samples. Some papers were screen printed with a conducting carbon-based ink to produce a photosensor device. Two methods were used to study the photocatalysis: immersing ZnO papers into kongo red dispersions or resazurin (Rz) based photocatalyst activity indicator ink and exposing the papers to ultraviolet (UV) light in a sunlight simulator. ZnO papers of approximately 60gsm were successfully produced on the pilot scale machine, which was run at a low speed (100m/min) and the retention of ZnO particles was good in all samples. The paper looked like an ordinary white printing paper product, but was a truly interactive material, exhibiting photoconductivity and enabling use as an excellent photosensor.

Pressure (P), temperature (T), and humidity (H) are physical key parameters of great relevance for various applications such as in distributed diagnostics, robotics, electronic skins, functional clothing, and many other Internet-of-Things (IoT) solutions. Previous studies on monitoring and recording these three parameters have focused on the integration of three individual single-parameter sensors into an electronic circuit, also comprising dedicated sense amplifiers, signal processing, and communication interfaces. To limit complexity in, e.g., multifunctional IoT systems, and thus reducing the manufacturing costs of such sensing/communication outposts, it is desirable to achieve one single-sensor device that simultaneously or consecutively measures P–T–H without cross-talks in the sensing functionality. Herein, a novel organic mixed ion–electron conducting aerogel is reported, which can sense P–T–H with minimal cross-talk between the measured parameters. The exclusive read-out of the three individual parameters is performed electronically in one single device configuration and is enabled by the use of a novel strategy that combines electronic and ionic Seebeck effect along with mixed ion–electron conduction in an elastic aerogel. The findings promise for multipurpose IoT technology with reduced complexity and production costs, features that are highly anticipated in distributed diagnostics, monitoring, safety, and security applications. © 2019 The Authors.

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.

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.

Ionic thermoelectric materials, for example, polyelectrolytes such as polystyrene sulfonate sodium (PSSNa),constitute a new class of materials which are attracting interest because of their large Seebeck coefficientand the possibility that they could be used in ionic thermoelectric SCs (ITESCs) and field effect transistors.However, pure polyelectrolyte membranes are not robust or flexible. In this paper, the preparation of ionicthermoelectric paper using a simple, scalable and cost-effective method is described. After a compositewas fabricated with nanofibrillated cellulose (NFC), the resulting NFC–PSSNa paper is flexible andmechanically robust, which is desirable if it is to be used in roll-to-roll processes. The robust NFC–PSSNa thermoelectric paper combines high ionic conductivity (9 mS cm1), high ionic Seebeckcoefficient (8.4 mV K1) and low thermal conductivity (0.75 W m1 K1) at 100% relative humidity,resulting in overall figure-of-merit of 0.025 at room temperature which is slightly better than that for thePSSNa alone. Fabricating a composite with cellulose enables flexibility and robustness and this is anadvance which will enable future scaling up the manufacturing of ITESCs, but also enables its use fornew applications for conformable thermoelectric devices and flexible electronics.

Due to growing concerns about the environmental impacts of fossil fuels and the capacity and resilience of energy grids around the world, engineers and policymakers are increasingly turning their attention to energy storage solutions1. In turn, the huge demand for materials for such storage systems will require a considerable energy input in extraction, processing and materials formulation, and new and sustainable electrochemical systems need to be developed2. Current report is the result of the exploration work where the circularity and environmental potentials of biobased energy storage solutions were analysed in the form of iterative interviews with stakeholders along the energy storage and packaging value chains, complemented by literature research. The work was performed within the scope of Digital Cellulose Center (DCC) research center3 in the sub-project 1 “Circularity of DCC materials” of the Theme 1: Design for a circular bioeconomy. Totally three systems were selected and analysed in the form of three respective case studies: • Case study I: Biobased battery (Chemical energy storage system) • Case study II: Biobased printed supercapacitor (Electrochemical energy storage system) • Case study III: Intelligent packaging (Chemical or electrochemical energy storage for fiber-based packaging) Each case study was put into the life cycle context where aspects such as legislation, circularity potential and potential environmental impact were discovered. The biobased battery for large-scale grid storage applications was classified as an industrial battery with collection rate requirement of 75% at end-of-life, of which 50% to be materially recycled. The biobased printed supercapacitor was classified as an electric and electronic equipment (EEE) with collection rate requirement of 65%, of which recovery and recycling / preparing for reuse targets vary between 55% - 85% depending on application. The material recycling target for the fiber-based intelligent packaging is 85% since being perceived as a paper-based packaging it would enter paper packaging recycling stream rather than entering the recycling stream of Waste electrical and electronic equipment (WEEE). In next steps of this exploratory journey, the compositions of the respective energy storage solutions were identified, including biobased content and recycling potential on the short- and long-term, compared to their benchmark solutions where possible. Today, the material recycling processes for batteries and WEEE are strongly economically driven: the material components that are considered as valuable by recyclers are mainly base metals (e.g., aluminium, steel) and to low extent critical raw materials (e.g., cobalt, nickel). The biobased energy storage solutions though do not contain any critical raw materials and use base metals to a less extent. This is a dilemma where the material value of the biobased, renewable materials (more sustainable materials by origin) is not favourable in the end-of-life processes of today and therefore will be lost (i.e., incinerated). A more balanced approach to such dilemma is urged in order to facilitate both economic and environmental incentives in the energy storage value cycles. Current Battery and WEEE directives do not promote the recycling of materials that are critical or have a high environmental burden, which in practice results in loss of those materials, not least due to lack of economy in recycling processes. Moreover, the legislation needs to be adapted in order to meet innovative development in the area. It can be relevant to introduce a cross-sectoral category ‘Biobased energy storage solutions’ in the upcoming legislation with the aim to encourage use of more abundant, biobased materials and thus decouple energy storage applications from use of critical raw materials.

The society is transitioning towards a circular economy and the Digital Cellulose Center (DCC) that develops green electronics may play an important role in it. The research within the DCC focuses on the topic of digital cellulose, where cellulose is combined with electroactive material, making it possible to develop electrically active cellulose products that can communicate with the digital world while remaining sustainable. This could mean entirely new types of active packaging solutions, able to sense and adapt to their surroundings, or paper rolls able to store energy from solar cells or wind power [1]. This document offers guidance for the DCC stakeholders on the choice of sustainable materials for green electronics, focusing on the two life cycle phases of a product: • Raw materials • End-of-life Since the DCC green electronics are still in the development stage, a future scenario analysis has been applied in order to envision the possible future outcomes. The DCC green electronics have been explored in two opposite future scenarios: • Stuck in the Mud – A business-as-usual scenario, where the year 2045 is more or less the same as year 2022. • Circular Dawn – Where the circular economy has become a new normal and the whole society is thriving in a resource-efficient, circular and biobased economy. The guideline contains a sustainability checklist adapted to the needs of the DCC stakeholders for more informed decision-making and for being able to drive the development towards a circular economy, i. e. the future scenario Circular Dawn.

Low voltage operated electrochemical devices can be produced from electrically conducting polymers and polyelectrolytes. Here, we report how such polymers and polyelectrolytes can be cast together with nanofibrillated cellulose (NFC) derived from wood. The resulting films, which carry ionic or electronic functionalities, are all-organic, disposable, light-weight, flexible, self-adhesive, elastic and self-supporting. The mechanical and self-adhesive properties of the films enable simple and flexible electronic systems by assembling the films into various kinds of components using a "cut and stick" method. Additionally, the self-adhesive surfaces provide a new concept that not only allows for simplified system integration of printed electronic components, but also allows for a unique possibility to detach and reconfigure one or several subcomponents by a "peel and stick" method to create yet another device configuration. This is demonstrated by a stack of two films that first served as the electrolyte layer and the pixel electrode of an electrochromic display, which then was detached from each other and transferred to another configuration, thus becoming the electrolyte and gate electrode of an electrochemical transistor. Further, smart pixels, consisting of the combination of one electrochromic pixel and one electrochemical transistor, have successfully been manufactured with the NFC-hybridized materials. The concept of system reconfiguration was further explored by that a pixel electrode charged to its colored state could be detached and then integrated on top of a transistor channel. This resulted in spontaneous discharging and associated current modulation of the transistor channel without applying any additional gate voltage. Our peel and stick approach promises for novel reconfigurable electronic devices, e.g. in sensor, label and security applications.

Electronically conducting polymers constitute an emerging class of materials for novel electronics, such as printed electronics and flexible electronics. Their properties have been further diversified to introduce elasticity, which has opened new possibility for "stretchable" electronics. Recent discoveries demonstrate that conducting polymers have thermoelectric properties with a low thermal conductivity, as well as tunable Seebeck coefficients - which is achieved by modulating their electrical conductivity via simple redox reactions. Using these thermoelectric properties, all-organic flexible thermoelectric devices, such as temperature sensors, heat flux sensors, and thermoelectric generators, are being developed. In this article we discuss the combination of the two emerging fields: stretchable electronics and polymer thermoelectrics. The combination of elastic and thermoelectric properties seems to be unique for conducting polymers, and difficult to achieve with inorganic thermoelectric materials. We introduce the basic concepts, and state of the art knowledge, about the thermoelectric properties of conducting polymers, and illustrate the use of elastic thermoelectric conducting polymer aerogels that could be employed as temperature and pressure sensors in an electronic-skin.

In moving towards a cellulose-based society, interdisciplinary effort is required as it is at this interface that new ideas are found and can grow. New bio-based materials will play a key role but getting them into the marketplace is not always straightforward. Many options are available both for sourcing and for producing composite materials from wood-based cellulose and poly-lactic acid (PLA). Depending on how the material is processed, a multitude of properties can be generated. The main goal with this work was to attempt to reduce the research-To-market gap. This was done by testing a new way of working together where we bundled innovation-oriented projects and research-oriented projects around the theme of material experience. We then systematically worked with material demonstrators. In this article, we exemplify the results by focusing on one research-oriented project that did not at the outset have a market context and on one innovation-oriented project with clear market requirements. In addition to introducing a new concept in bundling research-oriented and innovation-oriented projects, this paper contributes several practical examples of what material demonstrators can do. We also present an application and analysis of Moultrie’s extended Science-Technology-Application-Market (STAM) model to analyze the material demonstrators and design phases of the bundled projects. We modified the proposed classification with different types of material demonstrators according to how close they are to an actual product segment. Designers and scientists worked together but with different emphasis in each phase.

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.

Energy harvesting from photosynthetic membranes, proteins, or bacteria through bio-photovoltaic or bio-electrochemical approaches has been proposed as a new route to clean energy. A major shortcoming of these and solar cell technologies is the underutilization of solar irradiation wavelengths in the IR region, especially those in the far IR region. Here, a biohybrid energy-harvesting device is demonstrated that exploits IR radiation, via convection and thermoelectric effects, to improve the resulting energy conversion performance. A composite of nanocellulose and the conducting polymer system poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS) is used as the anode in biohybrid cells that includes thylakoid membranes (TMs) and redox mediators (RMs) in solution. By irradiating the conducting polymer electrode by an IR light-emitting diode, a sixfold enhancement in the harvested bio-photovoltaic power is achieved, without compromising stability of operation. Investigation of the output currents reveals that IR irradiation generates convective heat transfer in the electrolyte bulk, which enhances the redox reactions of RMs at the anode by suppressing diffusion limitations. In addition, a fast-transient thermoelectric component, originating from the PEDOT:PSS-nanocellulose-electrolyte interphase, further increases the bio-photocurrent. These results pave the way for the development of energy-harvesting biohybrids that make use of heat, via IR absorption, to enhance energy conversion efficiency. 

Paper machine manufacturing of photocatalysts can enable low cost devices for removal of low concentratedpollutants. Lateral variations originating from the paper making process leads to variations of the catalyticactivity over the paper area. Paper machine manufactured papers made from tetrapodal ZnO whiskers and kraftpulp were investigated in this test geometry using simulated solar light. Photocatalytic ZnO papers were laminatedbetween polyethylene sheets and an indicator solution seeped into the laminated photocatalytic paper, tocreate a test geometry where the indicator ink is confined to a small volume between the polyethylene sheets.The photocatalyst papers exhibited surprisingly similar photocatalytic behavior although having different catalystloading 15, 30 and 45 wt percent. All papers exhibited lateral variations that peaked during the conversion.The results show that production of effective photocatalytic composite papers can be scaled.Further, the results show that variations must be considered for photocatalytic papers.

Smartmaterials can be used for awide variety of applications, including sensing and energy harvesting.Implementation of smartmaterials in large area devices requires scalablemanufacturing. The use ofpaper-making techniques would offer an enormous production capacity, allowing for low-cost andlarge-scalemanufacturing. In thisworkwe present a successful pilot scale papermachinemanufacturingof functional composite papers(100mmin−1 with aweb width of 30 cm) based on cellulose fibres andcommercial tetrapodal zinc oxidemicrowhiskers(ZnO-Ts).Carbon electrodes could successfully beprinted on the paper to form complete electronic devices where the paper itself is the active material.Thisenabled development of aZnO-composite paper photosensor,where we characterized its stability,sensitivity and speed. The devices show excellent photosensing properties over awide range of lightirradiances(0.01–1Sun), including short response times (∼10 s) and long-term stability. Under simulatedsunlight and a bias voltage of 1 V, small(0.5 cm2) two-probe interdigitated photosensor devices provided12μAphotocurrent.Under the same conditions, four-probe measurements of the composite papershowed a sheet resistance of 6.9·107Ω/sq. Four-probe measurements also demonstrated that the paperconductivity varies linearlywith light irradiance. To the best of ourknowledge, this is thefirst example ofpilot paper machine production of an optoelectronic paper, demonstrating the potential for large-scalepapermanufacturing of active smart paper from low-cost industrial bulk materials.

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.

The conductive 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 conductive 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 conductive 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 devices.