Cotton-based nanocrystalline cellulose (NCC), also known as nanopaper, one of the major sources of renewable materials, is a promising substrate and component for producing low cost fully recyclable flexible paper electronic devices and systems due to its properties (lightweight, stiffness, non-toxicity, transparency, low thermal expansion, gas impermeability and improved mechanical properties).Here, we have demonstrated for the first time a thin transparent nanopaper-based field effect transistor (FET) where NCC is simultaneously used as the substrate and as the gate dielectric layer in an 'interstrate' structure, since the device is built on both sides of the NCC films; while the active channel layer is based on oxide amorphous semiconductors, the gate electrode is based on a transparent conductive oxide.Such hybrid FETs present excellent operating characteristics such as high channel saturation mobility (>7 cm(2) V (-1) s(-1)), drain-source current on/off modulation ratio higher than 10(5), enhancement n-type operation and subthreshold gate voltage swing of 2.11 V/decade. The NCC film FET characteristics have been measured in air ambient conditions and present good stability, after two weeks of being processed, without any type of encapsulation or passivation layer. The results obtained are comparable to ones produced for conventional cellulose paper, marking this out as a promising approach for attaining high-performance disposable electronics such as paper displays, smart labels, smart packaging, RFID (radio-frequency identification) and point-of-care systems for self-analysis in bioscience applications, among others.

A new concept for reusable eco‐friendly hydrogel electrolytes based on cellulose is introduced. The reported electrolytes are designed and engineered through a simple, fast, low‐cost, and eco‐friendly dissolution method of microcrystalline cellulose at low temperature using an aqueous LiOH/urea solvent system. The cellulose solution is combined with carboxymethyl cellulose, followed by the regeneration and simultaneous ion incorporation. The produced free standing cellulose‐based electrolyte films exhibit interesting properties for application in flexible electrochemical devices, such as biosensors or electrolyte‐gated transistors (EGTs), because of their high specific capacitances (4–5 µF cm−2), transparency, and flexibility. Indium–gallium–zinc‐oxide EGTs on glass with laminated cellulose‐based hydrogel electrolytes (CHEs) as the gate dielectric are produced presenting a low working voltage (<2 V), showing an on–off current ratio (Ion/off) of 106, a subthreshold swing lower than 0.2 V dec−1, and saturation mobility (μSat) reaching 26 cm2 V−1 s−1. The flexible CHE‐gated transistors on paper are also demonstrated, which operate at switching frequencies up to 100 Hz. Combining the flexibility of the EGTs on paper with the reusability of the developed CHEs is a breakthrough toward biodegradable advanced functional materials allied with disposable/recyclable and low‐cost electronic devices.

The world in the 21st century is confronted with multifaceted challenges against rapid climate change and continuous ecological disturbances caused by revolutionary socio‐economic developments, accelerated expansion of disposable electronic gadgets, and growing dependence on unrecyclable raw materials, among others. The ever‐increasing consumer demand for electronic devices is significantly contributing to the world's fastest‐growing waste stream, known as electronic waste (e‐waste), which is becoming an environmental threat at an alarming rate due to its toxic legacy. The ever‐shortening lifespan of smart technologies has created a “tsunami of e‐waste,” as the United Nations has characterized it, with 50 million tons accumulated each year, of which only 20% undergo formal e‐recycling. Therefore, the challenge of optimizing the current resources management models with an aim of improving the manufacturing processes and lifecycles of electronic devices, as well as building a circular economy, has become significantly prominent. Paper/cellulose, which covers a wide range of essential needs in everyday scenarios (from packaging to writing utilities), constitutes promising candidates for the effective achievement of a circular economy. Particularly, cellulose is revealed as an advantageous material for electronic applications because of its abundant availability, which contributes to its cost‐effectiveness, straightforward fabrication process, and high recyclability and reproducibility.

The integration of bioinspired chiral cellulose nanocrystal (CNC) films into transistor devices with distinct sensing properties for left‐ and right‐handed circular polarized light (LCPL and RCPL, respectively) is reported. The CNC films with a left‐handed internal long‐range order are infiltrated with sodium ions to yield solid‐state electrolytes with photonic properties capable of LCPL reflection and RCPL transmission. They are employed as gate dielectrics in sputtered amorphous indium–gallium–zinc oxide (a‐IGZO) transistors. The obtained devices operate in depletion mode at low voltages (<2 V) with On–Off ratios of up to 7 orders of magnitude, subthreshold swings around 80 mV dec−1, and saturation mobilities up to 9 cm2 V−1 s−1. Combining the photonic character of the CNC films with the light sensitivity of a‐IGZO, the devices are capable of discrimination between LCPL and RCPL signals in the blue region. These type of devices can find application in photonics, emission, conversion, or sensing with CPL but also imaging or spintronics.

is the deposition of oxide semiconductors that already demonstrated to be suitable for low power electronics [8] and for the development of logic circuits on paper substrates. [9] Recent research pointed to easier, faster, and less expensive approach for film deposition by using commercially available rollerball pens for the transfer of functional inks onto a wide range of substrates. This trend paves the way for the introduction of the PoP technique, where simple applications, as protein inks deposition, [10] conductive tracks, [11] piezoelectric devices, [12] or 3D antennas have already been demonstrated. [13] Nevertheless, in order to produce active devices, it is crucial to have as well a highly reliable and consistent method to deposit semiconductor materials using the same approach. By doing so, we pull printing and particularly PoP to a revolutionary technology stage, permitting the creation of low-cost and eco-friendly paper electronics "on-the-fly" by simply using a pen, proper functional inks, and a sheet of paper.To the best of the authors' knowledge, the successful deposition of inorganic semiconducting materials by the PoP technique has not yet been explored. Here, we report for the first time a method for a reliable deposition of ZnO nanoparticles (NPs) based dual-phase layer on paper substrates at room temperature (RT) by the PoP approach. These layers were used to fabricate hybrid fully printed/hand-drawn UV sensors and field effect transistors, where paper is simultaneously used as the physical support and as dielectric. Although the use of conventional rollerball pens is very appealing as a portable patterning instrument for paper-based printed/written electronics, only narrow lines (typically between 250 µm and 1 mm) can be drawn and the ink throughput is not always continuous. [13] For more complex and wider patterns, various parallel lines need to be drawn, where each line has to be in contact with the neighboring one to achieve a bidimensional functional film. This approach turns rollerball pen deposition process unpractical and difficult to control. In order to overcome this bottleneck we used a parallel metal plate pen, well-known from calligraphy applications, capable of dispensing ink over a large area (see Figure 1). Figure 1a shows the complete head of the used parallel pen and the two insets in Figure 1c illustrate the parallel plate structure, seen as side-and top-view in SEM, respectively (nib size of 6.0 mm). Here, the concept of direct ink passage becomes visually clear: whereas a rollerball pen disperses the ink by means of a rotating sphere, the parallel pen permits a direct ink flow between the two parallel metal plates. Thus, the ink flow depends on the capillary forces between the two plates and the The present work reports on the handwriting of electronic circuits on paper based on the deposition of an inorganic oxide semiconductor, exploiting the pen-on-paper (PoP) approach. The method relies on the use of a parallel metal plate pen, well known from calligraphy applications...