Cellulose has emerged as a promising sustainable material for advanced applications, including energy harvesting and sensing via triboelectric nanogenerators (TENGs). Despite significant progress in cellulosic TENGs, the role of carbonaceous nanomaterials with different morphologies and surface chemistries remains insufficiently understood. In this study, regenerated cellulose was used as a matrix to incorporate different carbon allotropes, including nanodiamonds, multi-walled carbon nanotubes (MWCNTs), and graphene nanoplatelets, to systematically evaluate their effect on triboelectric performance. Cellulose was dissolved in cold alkaline solution, and composites containing 2.5, 5, 7.5, 10, and 20 wt% of nanoparticles were prepared and tested as tribolayers against PTFE in a TENG configuration. The results showed that graphene-, MWCNT-, and nanodiamond-based composites improved power output by up to 76%, 51%, and 40%, respectively, compared to pure cellulose (34.3 W m−2). Physical and structural analyses, including dielectric spectroscopy, electrical conductivity measurements, scanning electron microscopy (SEM), atomic force microscopy (AFM), X-ray diffraction (XRD), FTIR, and Raman spectroscopy, were employed to investigate the structure-property relationships of regenerated cellulose‑carbon allotrope composites. The findings provide insight into the role of carbon nanomaterials in tuning the triboelectric behavior of regenerated cellulose and offer guidance for the design of high-performance, sustainable functional composites

The conducting polymer poly(3,4-ethylenedioxythiophene) (PEDOT) is well known for its fast and stable electrochromism. Recently, a patterning concept was developed in which ultraviolet (UV) light exposure modifies the growth rate of its p-toluenesulfonate derivative (PEDOT:Tos) during oxidative vapor phase polymerization, enabling continuous films with electrochromic patterns that can switch without supporting electrodes. However, the resulting contrast often deviates significantly from the intended exposure design, previously believed to originate from diffusion of mobile water. This study investigates that hypothesis by comparing oxidant blends containing short and long block copolymers (Pluronic L-31 and P-123), expected to create oxidant templates with different properties. Fourier-transform infrared spectroscopy reveals strong signatures of loosely bound water after UV exposure for all formulations, which diffuses transiently along the exposure boundary. Yet, the findings show that linewidth broadening does not correlate with diffusion but rather with additional macroscopic structuring outside the exposure boundary, which is absent at low (5 wt.%) block-copolymer concentration. Formulations with Pluronic L-31 provide a resist-free approach for achieving 2–3 µm electrochromic resolution in a standalone PEDOT:Tos film achieving switching times below 400 ms in aqueous electrolyte, and sustaining 2500 switching cycles in propylene glycol-based polyelectrolyte

Combining UV radiation with vapor phase polymerization (VPP) enables the fabrication of conducting polymer films with tunable electrical, optical, and electrochemical properties. However, traditional mask-based UV exposure typically requires separation between a photomask and the sample, which limits resolution. This study circumvents this by using a maskless UV exposure system that directly projects high-resolution patterns onto the substrate. Using poly(3,4-ethylenedioxythiophene):toluenesulfonate (PEDOT:Tos) as a model material, the resulting minimum feature sizes are approximately 8 µm—nearly half of what has been achieved using mask-based systems. We find that the obtained resolution is not limited by the optics but is related to material aspects such as molecular diffusion, providing guidelines for further optimizations. Our findings also show that the total delivered dose, rather than exposure time or irradiance, controls the film properties. The resulting PEDOT:Tos patterns exhibit distinct, stable color variations during electrochemical switching, highlighting the potential of maskless UV-VPP for high-resolution electrochromic displays.

Iron-catalyzed laser-induced graphitization (IC-LIG) represents an eco-efficient alternative to traditional carbon electrode manufacturing. Combining a bio-based tannic acid–iron precursor ink with CO<inf>2</inf> laser treatment results in sheet resistance of 23.59 ± 1.2Ω □−1 on renewable substrates. Varying the tannic-acid-to-iron ratio (TA:Fe), the rheology of the precursor ink can be tuned, enabling versatile application techniques, including spray coating, screen printing, and direct-ink-writing (DIW). Subsequent laser-treatment enables the formation of functional IC-LIG electrodes for all application methods, while even thick DIW-printed layers (260 µm) result in complex, conductive electrode patterns. Laser post-treatment expands design possibilities by locally tuning iron phases, such as converting γ-iron to magnetite. The unidirectional laser-treatment results in a layered arrangement, forming a multilayer electrode with a highly graphitized top layer serving as a current collector substitute, and an underlying composite of iron-rich nanoparticles embedded in a porous graphitic foam, acting as a hybrid electrode. Electrochemical analysis reveals double-layer capacitor behavior at low TA:Fe ratios, while higher ratios demonstrate increased redox activity and pseudo-capacitive characteristics. Achieving stable capacities of 15 mF cm−2 with a 1 M NaCl electrolyte over 5000 cycles underscores the potential of IC-LIG electrodes as a sustainable solution for advanced energy storage devices and beyond.

Energy storage devices, like redox-flow batteries and redox-supercapacitors, generate electrochemical potential by charging redox-active molecules. A key component in this class of devices is an ion-selective membrane that prevents redox-molecule crossover between half-cells, while allowing small ions to pass with minimal resistance. Conventional membranes often use ‘forever chemicals’ like Per-fluoroalkyl substances (PFAS), impacting their environmental footprint. This work introduces novel manufacturing methods for membranes made from coatings of cellulose nanofibril on kraft paper for use in these devices. The coating process is optimized to block redox-active molecules (e.g., alizarin red s and lignosulfonate) and enhance wet ionic conductivity. By refining the cellulose coating with chemical crosslinkers, leakage of redox molecules is reduced by an order of magnitude compared to uncoated kraft paper, without affecting conductivity. The goal is to pave the way for more environmentally friendly membranes in energy storage electrochemical cells. This innovation not only addresses environmental concerns but also the scalability of manufacturing, while maintaining the efficiency and functionality required for the envisioned applications.

With the increasing global demand for net-zero carbon emissions, actions to address climate change have gained momentum among policymakers and the public. The urgent need for a sustainable economy is underscored by the mounting waste crisis in landfills and oceans. However, the proliferation of distributed electronic devices poses a significant challenge due to the resulting electronic waste. To combat this issue, the development of sustainable and environmentally friendly materials for these devices is imperative. Cellulose, an abundant and CO2-neutral substance with a long history of diverse applications, holds great potential. By integrating electrically interactive components with cellulosic materials, innovative biobased composites have been created, enabling the fabrication of bulk electroactive paper and the establishment of new, potentially more sustainable manufacturing processes for electronic devices. This review explores recent advances in bulk electroactive paper, including the fundamental interactions between its constituents, manufacturing techniques, and large-scale applications in the field of electronics. Furthermore, it addresses the importance and challenges of scaling up production of electroactive paper, highlighting the need for further research and development.

The transition to a sustainable society is driving the development of green electronic solutions designed to have a minimal environmental impact. One promising route to achieve this goal is to construct electronics from biobased materials like cellulose, which is carbon neutral, non‐toxic, and recyclable. This is especially true for internet‐of‐things devices, which are rapidly growing in number and are becoming embedded in every aspect of our lives. Here, paper‐based sensor circuits are demonstrated, which use triboelectric pressure sensors to help elderly people communicate with the digital world using an interface in the form of an electronic “book”, which is more intuitive to them. The sensors are manufactured by screen printing onto flexible paper substrates, using in‐house developed cellulose‐based inks with non‐hazardous solvents. The triboelectric sensor signal, generated by the contact between a finger and chemically modified cellulose, can reach several volts, which can be registered by a portable microcontroller card and transmitted by Bluetooth to any device with an internet connection. Apart from the microcontroller (which can be easily removed), the whole system can be recycled at the end of life. A triboelectric touch interface, manufactured using printed electronics on flexible paper substrates, using cellulose‐based functional inks is demonstrated. These metal‐free green electronics circuits are implemented in an “electronic book” demonstrator, equipped with wireless communication that can control remote devices, as a step toward sustainable and recyclable internet‐of‐things devices.

Displays are one of the most mature technologies in the field of printed electronics. Their ability to be manufactured in large quantities and at low cost has led to their recent uptake into the consumer market. Within this article this technology is extended to electrochromic display stickers. This is achieved using a recent reverse display architecture screen printed on textile and paper sticker substrates. The electrochromic stickers are comparable to plastic control substrates and show little performance difference even when adhered to curved surfaces. The electrochromic display technology is extended to sticker labels for authentication applications by patterning either the dielectric or the graphical layer. A proof-of-concept prototype emulating a wax seal on an envelope is presented to show that other colors can be implemented in this technology. © 2023 The Authors.

Low-cost, flexible and thin display technology is becoming an interesting field of research as it can accompany the wide range of sensors being developed. Here, the synthesis of poly(dimethylpropylene-dioxythiophene) (PProDOT-Me2) by combining vapor phase polymerization and screen printing is presented. A multilayer architecture using poly(3,4-ethylenedioxythiophene) (PEDOT) and PProDOT-Me2 to allow for electrochromic switching of PProDOT-Me2, thereby eliminating the need for a supporting transparent conductive (metal oxide) layer is introduced. Furthermore, the technology is adapted to a blended architecture, which removes the additional processing steps and results in improved color contrast (∆E* &gt; 25). This blend architecture is extended to other conductive polymers, such as PEDOT and polypyrrole (PPy), to highlight the ability of the technique to adjust the color of all-printed electrochromic displays. As a result, a green color is obtained when combining the blue and yellow states of PEDOT and PPy, respectively. This technology has the potential to pave the way for all-printed multicolored electrochromic displays for further utilization in printed electronic systems in various Internet of Things applications. © 2022 The Authors. 

Manufacturing of electronic devices via printing techniques is often considered to be an environmentally friendly approach, partially due to the efficient utilization of materials. Traditionally, printed electronic components (e.g., sensors, transistors, and displays) are relying on flexible substrates based on plastic materials; this is especially true in electronic display applications where, most of the times, a transparent carrier is required in order to enable presentation of the display content. However, plastic-based substrates are often ruled out in end user scenarios striving toward sustainability. Paper substrates based on ordinary cellulose fibers can potentially replace plastic substrates, but the opaqueness limits the range of applications where they can be used. Herein, electrochromic displays that are manufactured, via screen printing, directly on state-of-the-art fully transparent substrates based on nanocellulose are presented. Several different nanocellulose-based substrates, based on either nanofibrillated or nanocrystalline cellulose, are manufactured and evaluated as substrates for the manufacturing of electrochromic displays, and the optical and electrical switching performances of the resulting display devices are reported and compared. The reported devices do not require the use of metals and/or transparent conductive oxides, thereby providing a sustainable all-printed electrochromic display technology.