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The rise of internet of things (IoTs) applications has led to the development of a new generation of light‐weight, flexible, and cost‐effective electronics. These devices and sensors have to be simultaneously easily replaceable and disposable while being environmentally sustainable. Thus, the introduction of new functionalized materials with mechanical flexibility that can be processed using large‐area and facile fabrication methods (as, for example, printing technologies) has become a matter of great interest in the scientific community. In this context, cellulose nanofibers (CNFs) are renewable, affordable, robust, and nontoxic materials that are rapidly emerging as components for eco‐friendly electronics. Their combination with conductive polymers (CPs) to obtain conductive nanopapers (CNPs) allows moving their functionality from just substrates to active components of the device. In this work, a route for the inkjet‐printing of organic diodes is outlined. The proposed strategy is based on the use of CNPs as both substrates and bottom electrodes onto which insulator and organic semiconducting layers are deposited to fabricate novel diode structures. Remarkable rectification ratios of up to 1.2 × 103 at |3 V| and a current density up to 5.1 µA cm−2 are achieved. As a proof‐of‐concept of the potentiality of the approach for versatile, low‐temperature, and disposable sensing applications, an NO2 gas sensor is presented. [ABSTRACT FROM AUTHOR]

Abstract The fabrication of diodes by inkjet printing has been hampered by difficulties in printing low work function metals required to establish Schottky barriers with organic semiconductors. This limitation has been a major roadblock in the use of inkjet printing technology for the development of organic rectifying diodes. This paper presents the fabrication and characterization of a novel inkjet-printed metal- organic insulator- organic semiconductor diode on flexible plastic substrates. The structure consists of a polymeric insulator/semiconductor interface sandwiched between two silver electrodes. It is proposed that the rectification properties are due to a voltage controlled leakage current across the insulator/semiconductor interface. The current across the insulator is caused by the formation of a semiconductor brush-like morphology into the underneath porous insulator layer. The carrier injection into the insulator follows a thermionic emission model. Temperature dependent measurements reveal an interfacial barrier height between 0.97 eV and 0.36 eV depending on the morphology and type of insulator layer used. Metal- organic insulator- organic semiconductor based diodes show rectification ratios up to 150 at |10V| and a current density up to approximately 1 μAcm−2. The simple fabrication process of the diodes also makes it advantageous for scaling up to roll-to-roll production. Graphical abstract Image 1 Highlights • The organic Metal-Insulator-Semiconductor (MIS) based diodes show a rectification ratios of 150 at |10V| and a current density of 1 μAcm−2. • It is shown that inkjet printing can be used to fabricate rectifying diodes using a MIS structure and ohmic metal contacts. • The semiconductor-polymer intermixing creates a polymer brush-like morphology that thinner the insulating polymer layer. • The physical model proposed for MIS diodes is only dependent on the insulator morphology and independent of the type of polymer used. [ABSTRACT FROM AUTHOR]

Organic Electronics provides multiple technological advantages such as low cost, flexibility, solution processability and waste reduction through the use of new materials and alternative fabrication techniques in the microelectronic world. The use of additive and printed fabrication processes allows the development of instantly fabricated, fully additive, low temperature processing together with lightweight, bendable, scalable and sustainable systems. Different models have been presented in the field but none of them with an industrial implementation. Complete simulation models are very useful for circuit production and commercialization since the organic electronics market is expected to grow in the near future and the need for industrial solutions for designers will increase. For this reason and for the first time, we present a compact model of DC and AC behaviour combined with different ambient conditions and parameter variability for full organic electronic system simulations. [Display omitted] • Device variability study under different ambient circumstances. • A model involving continuous and transient domains, simulation and validation. • Model parameters variability modelled and simulated in different circuits. • Pelgrom's law validation in organic electronics devices. [ABSTRACT FROM AUTHOR]

A flexible, biological field-effect transistor (BioFET) for use in biosensing is reported. The BioFET is based on an organic thin-film transistor (OTFT) fabricated mainly by inkjet printing and subsequently functionalized with antibodies for protein recognition. The BioFET is assessed for label-free detection of a model protein, human immunoglobulin G (HIgG). It is characterized electrically to evaluate the contribution of each step in the functionalization of the OTFT and to detect the presence of the target protein. The fabrication, structure, materials optimization, electrical characteristics, and functionality of the starting OTFT and final BioFET are also discussed. Different materials are evaluated for the top insulator layer, with the aim of protecting the lower layers from the electrolyte and preserving the BioFET electrical performance. [ABSTRACT FROM AUTHOR]

Biosensors based on Organic Field-Effect Transistors (OFETs) have attracted increasing attention due to the possibility of rapid, label-free, and inexpensive detection. Among all the different possibilities, inkjet-printed top-gate organic Field Effect Transistors-Based Biosensors (BioFETs) using a polymeric gate insulator have been seldom reported. In this work, a systematic investigation in terms of topographical and electrical characterization was carried out in order to find the optimal fabrication process for obtaining a reliable polymer insulator. Previous studies have demonstrated that the best electrical performance arises from the use of the perfluoropolymer Cytop™[12,13,14]. Consequently, a simple immobilization protocol was used to ensure the proper attachment of a model biomolecule onto the Cytop's hydrophobic surface whilst keeping its remarkable insulating properties with gate current in the range of dozens of pico-amperes. The top-gate inkjet-printed BioFETs presented in this study operate at threshold voltages in the range of 1–2 V and show durability even when exposed to oxygen plasma, wet amine functionalization treatments, and aqueous media. As a preliminary application, the inkjet-printed top-gate BioFETs is used for monitoring an immunoreaction by measuring changes in the drain current, paving the way for further use of this device in the immunosensing field. A systematic study and optimization of a simple functionalization procedure to attach antibodies onto Cytop film for obtaining inkjet printed top-gate BioFETs is presented. Image 1 • · The proposed inkjet-printed organic transistor-based flexible sensor delivers a label-free response for immunosensing applications. • It is shown that the use of the perfluoropolymer Cytop as gate insulator presents the best electrical performance in terms of leakage current. • A functionalization procedure is presented to attach biomolecules onto the Cytop surface while keeping its remarkable insulating properties. • The BioFET has been evaluated as a proof-of-concept sensor to detect a model biomolecule through drain current changes. [ABSTRACT FROM AUTHOR]