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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., QC 20230308

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., QC 20210903

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

Paper is emerging as a promising flexible, high surface-area substrate for various new applications such as printed electronics, energy storage, and paper-based diagnostics. Many applications, however, require paper that reaches metallic conductivity levels, ideally at low cost. Here, an aqueous electroless copper-plating method is presented, which forms a conducting thin film of fused copper nanoparticles on the surface of the cellulose fibers. This paper can be used as a current collector for anodes of lithium-ion batteries. Owing to the porous structure and the large surface area of cellulose fibers, the copper-plated paper-based half-cell of the lithium-ion battery exhibits excellent rate performance and cycling stability, and even outperforms commercially available planar copper foil-based anode at ultra-high charge/discharge rates of 100 C and 200 C. This mechanically robust metallic-paper composite has promising applications as the current collector for light-weight, flexible, and foldable paper-based 3D Li-ion battery anodes., QC 20190625

We report a flexible self-standing adhesive composite made from PEDOT:PSS and nanofibrillated cellulose. The material exhibits good combined mechanical and electrical characteristics (an elastic modulus of 4.4 MPa, and an electrical conductivity of 30 S cm(-1)). The inherent self-adhesiveness of the material enables it to be laminated and delaminated repeatedly to form and reconfigure devices and circuits. This modular property opens the door for a plethora of applications where reconfigurability and ease-of-manufacturing are of prime importance. We also demonstrate a paper composite with ionic conductivity and combine the two materials to construct electrochemical devices, namely transistors, capacitors and diodes with high values of transconductance, charge storage capacity and current rectification. We have further used these devices to construct digital circuits such as NOT, NAND and NORlogic., QC 20180130

In this work, we report macroscopic electromagnetic devices made from conducting polymers. We compare their fundamental properties and device parameters with those of similar devices made from copper wires. By using self-standing supra-ampere conducting polymer wires, we are able to manufacture inductors that generate magnetic fields well over 1 G, and incorporate them in feedback LC oscillators operating at 8.65 MHz. Moreover, by utilizing the unique electrochemical functionality of conducting polymers, we demonstrate electrochemically-tunable electromagnets and electromagnetic chemical sensors. Our findings pave the way to lightweight electromagnetic technologies that can be processed (fromwater dispersions) using low-temperature protocols into flexible shapes and geometries., QC 20171023

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., QC 20160319

Electrochromic displays based on conducting polymers exhibit higher contrasts and are cheaper, faster, more durable, and easier to synthesize as well as to process than their non-polymeric counterparts. However, current devices are typically based on thin electrochromic layers on top of a reflecting surface, which limits the thickness of the polymer layer to a few hundred nanometers. Here, we embed a light-scattering material within the electrochromic material to achieve a freestanding electrochromic paper-like electrode (50 to 500 mm). The device is based on a cellulose composite combining PEDOT:PSS as the electrochromic material and TiO2 nanoparticles as the reflecting material. Owing to the excellent refractive properties of TiO2, this nanocomposite is white in the neutral state and, when reduced, turns blue resulting in a color contrast around 30. The composite has a granular morphology and, as shown by AFM, an intermingling of TiO2 and PEDOT: PSS at the surface. Variation of the amount of TiO2 within the composite material is shown to result in a trade-off in optical and electrical properties. A proof-of-concept freestanding electrochromic device was fabricated by casting all layers successively to maximize the interlayer conformation. This freestanding device was found to be stable for over 100 cycles when ramped between 3 and -3 V., Funding Agencies|Knut and Alice Wallenberg foundation [KAW 2011.0050]

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.

Conducting polymers with bipolar membranes (a complementary stack of selective membranes) may be used to rectify current. Integrating a bipolar membrane into a polymer electrochromic display obviates the need for an addressing backplane while increasing the devices bistability. Such devices can be made from solution-processable materials., Funding Agencies|Swedish foundation for strategic research; Knut and Alice Wallenberg foundation; VINNOVA; Advanced Functional Materials Center at Linkoping University; European Research Council [307596]

Electrochromic displays based on conducting polymers offer higher contrast, are cheaper, faster, more durable, and easier to synthesize as well as to process than their non-polymeric counterparts. The field of organic electrochromics has made considerable strides in the last decade with the development of new materials and methods. Here, we present a cellulose composite combining PEDOT:PSS and TiO2 that is a free-standing electrochromic material. Owing to the excellent refractive properties of TiO2, this nanocomposite is white in the neutral state and, when reduced, turns blue resulting in a color contrast exceeding 30. The composite has a granular morphology and, as shown by AFM, an intermingling of TiO2 and PEDOT:PSS at the surface. Variation of TiO2 within the material led to a trade-off in optical and electrical properties. A proof of concept free-standing electrochromic device was fabricated by casting several layers, which was found to be stable over 100 cycles.

Exploiting the nanoscale properties of certain materials enables the creation of new materials with a unique set of properties. Here, we report on an electronic (and ionic) conducting paper based on cellulose nanofibrils (CNF) composited with poly(3,4-ethylene-dioxythiophene):poly(styrene-sulfonate) (PEDOT:PSS), which may be facilely processed into large three-dimensional geometries, while keeping unprecedented electronic and ionic conductivities of 140 S/cm and 20 mS/cm, respectively. This is achieved by cladding the CNF with PEDOT:PSS, and trapping an ion-transporting phase in the interstices between these nanofibrils. The unique properties of the resulting nanopaper composite have been used to demonstrate (electrochemical) transistors, supercapacitors and conductors resulting in exceptionally high device parameters, such as an associated transconductance, charge storage capacity and current level beyond 1 S, 1 F and 1 A, respectively.

Organic transistors that use polyelectrolytes as gate insulators can be driven at very low voltages (andlt;1 V). The low operating voltage is possible thanks to the formation of electric double layers upon polarization, which generates large electric fields at the critical interfaces in the device structure. In this work, we use a semiconducting blend (of a high electron affinity polymer and a low ionization potential one) in conjunction with a solid polyelectrolyte insulator to fabricate low-voltage ambipolar organic transistors. For both n- and p-channel operation, we use a polycation with readily mobile-yet large enough to limit bulk doping of the semiconductor-counterions., Funding Agencies|EU through the EC|212311|Swedish Government (Advanced Functional Materials)||Swedish Foundation for Strategic Research (OPEN)||Knut and Alice Wallenberg Foundation||Onnesjo Foundation

Complementary circuits, processing digital signals, are a cornerstone of modern electronics. Such circuits require both p-and n-type transistors. Polyelectrolytes are used as gate insulators in organic thin film transistors (OTFTs) to establish an electric double layer capacitor upon gate bias that allows low operational voltages (andlt;1 V). However, stable and low-voltage operating n-channel organic transistors have proven difficult to construct. Here, we report ultra-low voltage n-channel organic polymer-based transistors that are stable in ambient atmosphere. Our n-type OTFTs exhibit on/off ratios around 10(3) for an applied drain potential as low as 0.1 V. Since small ions are known to promote electrochemical reactions within the semiconductors channel bulk and typically slow down the transistor, we use a solid polycationic gate insulator that suppresses penetration of anions into the n-channel semiconductor. As a result, our n-channel OTFTs switch on in under 5 ms and off in less than 1 ms., Swedish Government||Swedish Foundation for Strategic Research (OPEN)||Knut and Alice Wallenberg Foundation||Onnesjo Foundation

Thermoelectric generators (TEGs) transform a heat flow into electricity. Thermoelectric materials are being investigated for electricity production from waste heat (co-generation) and natural heat sources. For temperatures below 200 degrees C, the best commercially available inorganic semiconductors are bismuth telluride (Bi2Te3)-based alloys, which possess a figure of merit ZT close to one(1). Most of the recently discovered thermoelectric materials with ZT andgt; 2 exhibit one common property, namely their low lattice thermal conductivities(2,3). Nevertheless, a high ZT value is not enough to create a viable technology platform for energy harvesting. To generate electricity from large volumes of warm fluids, heat exchangers must be functionalized with TEGs. This requires thermoelectric materials that are readily synthesized, air stable, environmentally friendly and solution processable to create patterns on large areas. Here we show that conducting polymers might be capable of meeting these demands. The accurate control of the oxidation level in poly(3,4-ethylenedioxythiophene) (PEDOT) combined with its low intrinsic thermal conductivity (lambda = D 0.37W m(-1) K-1) yields a ZT = 0.25 at room temperature that approaches the values required for efficient devices.