Solubilizing Benzodifuranone-Based Conjugated Copolymers with Single-Oxygen-Containing Branched Side Chains.

Single-oxygen-containing branched side chains are designed and used to solubilize n-type copolymers consisting of BDF (benzodifuranone), isatin, and thiophene-based units. We present a simple synthetic approach to side chains with varying linker distances between the backbone and the branching point. The synthetic pathway is straightforward and modular and starts with commercially available reagents. The side chains give rise to excellent solubilities of BDF-thiophene copolymers of up to 90 mg/mL, while still being moderate in size (26-34 atoms large). The excellent solubility furthermore allows high molar mass materials. BDF-thiophene copolymers are characterized in terms of optoelectronic and thermoelectric properties. The electrical conductivity of chemically doped polymers is found to scale with molar mass, reaching ∼1 S/cm for the highest molar mass and longest backbone-branching point distance.

Analysis of Clinical Samples of Pancreatic Cyst's Lesions with A Multi-Analyte Bioelectronic Simot Array Benchmarked Against Ultrasensitive Chemiluminescent Immunoassay.

Pancreatic cancer, ranking as the third factor in cancer-related deaths, necessitates enhanced diagnostic measures through early detection. In response, SiMoT-Single-molecule with a large Transistor multiplexing array, achieving a Technology Readiness Level of 5, is proposed for a timely identification of pancreatic cancer precursor cysts and is benchmarked against the commercially available chemiluminescent immunoassay SIMOA (Single molecule array) SP-X System. A cohort of 39 samples, comprising 33 cyst fluids and 6 blood plasma specimens, undergoes detailed examination with both technologies. The SiMoT array targets oncoproteins MUC1 and CD55, and oncogene KRAS, while the SIMOA SP-X planar technology exclusively focuses on MUC1 and CD55. Employing Principal Component Analysis (PCA) for multivariate data processing, the SiMoT array demonstrates effective discrimination of malignant/pre-invasive high-grade or potentially malignant low-grade pancreatic cysts from benign non-mucinous cysts. Conversely, PCA analysis applied to SIMOA assay reveals less effective differentiation ability among the three cyst classes. Notably, SiMoT unique capability of concurrently analyzing protein and genetic markers with the threshold of one single molecule in 0.1 mL positions it as a comprehensive and reliable diagnostic tool. The electronic response generated by the SiMoT array facilitates direct digital data communication, suggesting potential applications in the development of field-deployable liquid biopsy.

Preparation of different conjugated polymers characterized by complementary electronic properties from an identical precursor.

The possibility of generating regions with different electronic properties within the same organic semiconductor thin film could offer novel opportunities for designing and fabricating organic electronic devices and circuits. This study introduces a new approach based on a novel type of highly processable polymer precursor that can yield two different conjugated polymers characterized by complementary electronic properties, i.e. promoting electron or hole transport, from the same starting material. In particular, these multipotent precursors comprise functionalized dihydroanthracene units that can offer several functionalization opportunities to improve the solubility or insert specific functionalities. This strategy also allows for the preparation of high-molecular-weight conjugated polymers comprising diethynylanthracene and anthraquinone units without the need for solubilizing side chains. Thin films of the polymer precursor can be used, after solid-state transformations, to prepare single organic layers comprising regions characterized by different chemical nature and electronic properties. Here, we present a detailed characterization of the chemical and electronic properties of the precursor and the obtained conjugated polymers, showing how it is possible to harvest their characteristics for potential applications such as electrochromic surfaces and organic field-effect transistors.

Solution-Processed Polymer Dielectric Interlayer for Low-Voltage, Unipolar n-Type Organic Field-Effect Transistors.

The integration of organic electronic circuits into real-life applications compels the fulfillment of a range of requirements, among which the ideal operation at a low voltage with reduced power consumption is paramount. Moreover, these performance factors should be achieved via solution-based fabrication schemes in order to comply with the promise of cost- and energy-efficient manufacturing offered by an organic, printed electronic technology. Here, we propose a solution-based route for the fabrication of low-voltage organic transistors, encompassing ideal device operation at voltages below 5 V and exhibiting n-type unipolarization. This process is widely applicable to a variety of semiconducting and dielectric materials. We achieved this through the use of a photo-cross-linked, low-k dielectric interlayer, which is used to fabricate multilayer dielectric stacks with areal capacitances of up to 40 nF/cm2 and leakage currents below 1 nA/cm2. Because of the chosen azide-based cross-linker, the dielectric promotes n-type unipolarization of the transistors and demonstrated to be compatible with different classes of semiconductors, from conjugated polymers to carbon nanotubes and low-temperature metal oxides. Our results demonstrate a general applicability of our unipolarizing dielectric, facilitating the implementation of complementary circuitry of emerging technologies with reduced power consumption.

A Single-Molecule Bioelectronic Portable Array for Early Diagnosis of Pancreatic Cancer Precursors.

A cohort of 47 patients is screened for pancreatic cancer precursors with a portable 96-well bioelectronic sensing-array for single-molecule assay in cysts fluid and blood plasma, deployable at point-of-care (POC). Pancreatic cancer precursors are mucinous cysts diagnosed with a sensitivity of at most 80% by state-of-the-art cytopathological molecular analyses (e.g., KRASmut DNA). Adding the simultaneous assay of proteins related to malignant transformation (e.g., MUC1 and CD55) is deemed essential to enhance diagnostic accuracy. The bioelectronic array proposed here, based on single-molecule-with-a-large-transistor (SiMoT) technology, can assay both nucleic acids and proteins at the single-molecule limit-of-identification (LOI) (1% of false-positives and false-negatives). It comprises an enzyme-linked immunosorbent assay (ELISA)-like 8 × 12-array organic-electronics disposable cartridge with an electrolyte-gated organic transistor sensor array, and a reusable reader, integrating a custom Si-IC chip, operating via software installed on a USB-connected smart device. The cartridge is complemented by a 3D-printed sensing gate cover plate. KRASmut , MUC1, and CD55 biomarkers either in plasma or cysts-fluid from 5 to 6 patients at a time, are multiplexed at single-molecule LOI in 1.5 h. The pancreatic cancer precursors are classified via a machine-learning analysis resulting in at least 96% diagnostic-sensitivity and 100% diagnostic-specificity. This preliminary study opens the way to POC liquid-biopsy-based early diagnosis of pancreatic-cancer precursors in plasma.

Chitosan-gated organic transistors printed on ethyl cellulose as a versatile platform for edible electronics and bioelectronics.

Edible electronics is an emerging research field targeting electronic devices that can be safely ingested and directly digested or metabolized by the human body. As such, it paves the way to a whole new family of applications, ranging from ingestible medical devices and biosensors to smart labelling for food quality monitoring and anti-counterfeiting. Being a newborn research field, many challenges need to be addressed to realize fully edible electronic components. In particular, an extended library of edible electronic materials is required, with suitable electronic properties depending on the target device and compatible with large-area printing processes, to allow scalable and cost-effective manufacturing. In this work, we propose a platform for future low-voltage edible transistors and circuits that comprises an edible chitosan gating medium and inkjet-printed inert gold electrodes, compatible with low thermal budget edible substrates, such as ethylcellulose. We report the compatibility of the platform, characterized by critical channel features as low as 10 µm, with different inkjet-printed carbon-based semiconductors, including biocompatible polymers present in the picogram range per device. A complementary organic inverter is also demonstrated with the same platform as a proof-of-principle logic gate. The presented results offer a promising approach to future low-voltage edible active circuitry, as well as a testbed for non-toxic printable semiconductors.

An Edible Rechargeable Battery.

Edible electronics is a growing field that aims to produce digestible devices using only food ingredients and additives, thus addressing many of the shortcomings of ingestible electronic devices. Edible electronic devices will have major implications for gastrointestinal tract monitoring, therapeutics, as well as rapid food quality monitoring. Recent research has demonstrated the feasibility of edible circuits and sensors, but to realize fully edible electronic devices edible power sources are required, of which there have been very few examples. Drawing inspiration from living organisms, which use redox cofactors to power biochemical machines, a rechargeable edible battery formed from materials eaten in everyday life is developed. The battery is realized by immobilizing riboflavin and quercetin, common food ingredients and dietary supplements, on activated carbon, a widespread food additive. Riboflavin is used as the anode, while quercetin is used as the cathode. By encapsulating the electrodes in beeswax, a fully edible battery is fabricated capable of supplying power to small electronic devices. The proof-of-concept battery cell operated at 0.65 V, sustaining a current of 48 µA for 12 min. The presented proof-of-concept will open the doors to new edible electronic applications, enabling safer and easier medical diagnostics, treatments, and unexplored ways to monitor food quality.

Self-Powered Edible Defrosting Sensor.

Improper freezing of food causes food waste and negatively impacts the environment. In this work, we propose a device that can detect defrosting events by coupling a temperature-activated galvanic cell with an ionochromic cell, which is activated by the release of ions during current flow. Both the components of the sensor are fabricated through simple and low-energy-consuming procedures from edible materials. The galvanic cell operates with an aqueous electrolyte solution, producing current only at temperatures above the freezing point of the solution. The ionochromic cell exploits the current generated during the defrosting to release tin ions, which form complexes with natural dyes, causing the color change. Therefore, this sensor provides information about defrosting events. The temperature at which the sensor reacts can be tuned between 0 and -50 °C. The device can thus be flexibly used in the supply chain: as a sensor, it can measure the length of exposure to above-the-threshold temperatures, while as a detector, it can provide a signal that there was exposure to above-the-threshold temperatures. Such a device can ensure that frozen food is handled correctly and is safe for consumption. As a sensor, it could be used by the workers in the supply chain, while as a detector, it could be useful for end consumers, ensuring that the food was properly frozen during the whole supply chain.

Effects of Molecular Encapsulation on the Photophysical and Charge Transport Properties of a Naphthalene Diimide Bithiophene Copolymer.

Engineering the molecular structure of conjugated polymers is key to advancing the field of organic electronics. In this work, we synthesized a molecularly encapsulated version of the naphthalene diimide bithiophene copolymer PNDIT2, which is among the most popular high charge mobility organic semiconductors in n-type field-effect transistors and non-fullerene acceptors in organic photovoltaic blends. The encapsulating macrocycles shield the bithiophene units while leaving the naphthalene diimide units available for intermolecular interactions. With respect to PNDIT2, the encapsulated counterpart displays an increased backbone planarity. Molecular encapsulation prevents preaggregation of the polymer chains in common organic solvents, while it permits π-stacking in the solid state and promotes thin film crystallinity through an intermolecular-lock mechanism. Consequently, n-type semiconducting behavior is retained in field-effect transistors, although charge mobility is lower than in PNDIT2 due to the absence of the fibrillar microstructure that originates from preaggregation in solution. Hence, molecularly encapsulating conjugated polymers represent a promising chemical strategy to tune the molecular interaction in solution and the backbone conformation and to consequently control the nanomorphology of casted films without altering the electronic structure of the core polymer.

A large-area organic transistor with 3D-printed sensing gate for noninvasive single-molecule detection of pancreatic mucinous cyst markers.

Early diagnosis in a premalignant (or pre-invasive) state represents the only chance for cure in neoplastic diseases such as pancreatic-biliary cancer, which are otherwise detected at later stages and can only be treated using palliative approaches, with no hope for a cure. Screening methods for the purpose of secondary prevention are not yet available for these cancers. Current diagnostic methods mostly rely on imaging techniques and conventional cytopathology, but they do not display adequate sensitivity to allow valid early diagnosis. Next-generation sequencing can be used to detect DNA markers down to the physical limit; however, this assay requires labeling and is time-consuming. The additional determination of a protein marker that is a predictor of aggressive behavior is a promising innovative approach, which holds the potential to improve diagnostic accuracy. Moreover, the possibility to detect biomarkers in blood serum offers the advantage of a noninvasive diagnosis. In this study, both the DNA and protein markers of pancreatic mucinous cysts were analyzed in human blood serum down to the single-molecule limit using the SiMoT (single-molecule assay with a large transistor) platform. The SiMoT device proposed herein, which exploits an inkjet-printed organic semiconductor on plastic foil, comprises an innovative 3D-printed sensing gate module, consisting of a truncated cone that protrudes from a plastic substrate and is compatible with standard ELISA wells. This 3D gate concept adds tremendous control over the biosensing system stability, along with minimal consumption of the capturing molecules and body fluid samples. The 3D sensing gate modules were extensively characterized from both a material and electrical perspective, successfully proving their suitability as detection interfaces for biosensing applications. KRAS and MUC1 target molecules were successfully analyzed in diluted human blood serum with the 3D sensing gate functionalized with b-KRAS and anti-MUC1, achieving a limit of detection of 10 zM and 40 zM, respectively. These limits of detection correspond to (1 ± 1) KRAS and (2 ± 1) MUC1 molecules in the 100 µL serum sample volume. This study provides a promising application of the 3D SiMoT platform, potentially facilitating the timely, noninvasive, and reliable identification of pancreatic cancer precursor cysts.

Stable and Solution-Processable Cumulenic sp-Carbon Wires: A New Paradigm for Organic Electronics.

Solution-processed, large-area, and flexible electronics largely relies on the excellent electronic properties of sp2 -hybridized carbon molecules, either in the form of π-conjugated small molecules and polymers or graphene and carbon nanotubes. Carbon with sp-hybridization, the foundation of the elusive allotrope carbyne, offers vast opportunities for functionalized molecules in the form of linear carbon atomic wires (CAWs), with intriguing and even superior predicted electronic properties. While CAWs represent a vibrant field of research, to date, they have only been applied sparingly to molecular devices. The recent observation of the field-effect in microcrystalline cumulenes suggests their potential applications in solution-processed thin-film transistors but concerns surrounding the stability and electronic performance have precluded developments in this direction. In the present study, ideal field-effect characteristics are demonstrated for solution-processed thin films of tetraphenyl[3]cumulene, the shortest semiconducting CAW. Films are deposited through a scalable, large-area, meniscus-coating technique, providing transistors with hole mobilities in excess of 0.1 cm2  V-1  s-1 , as well as promising operational stability under dark conditions. These results offer a solid foundation for the exploitation of a vast class of molecular semiconductors for organic electronics based on sp-hybridized carbon systems and create a previously unexplored paradigm.

Time-Dependent Field Effect in Three-Dimensional Lead-Halide Perovskite Semiconductor Thin Films.

Charge transport in three-dimensional metal-halide perovskite semiconductors is due to a complex combination of ionic and electronic contributions, and its study is particularly relevant in light of their successful applications in photovoltaics as well as other opto- and microelectronic applications. Interestingly, the observation of field effect at room temperature in transistors based on solution-processed, polycrystalline, three-dimensional perovskite thin films has been elusive. In this work, we study the time-dependent electrical characteristics of field-effect transistors based on the model methylammonium lead iodide semiconductor and observe the drastic variations in output current, and therefore of apparent charge carrier mobility, as a function of the applied gate pulse duration. We infer this behavior to the accumulation of ions at the grain boundaries, which hamper the transport of carriers across the FET channel. This study reveals the dynamic nature of the field effect in solution-processed metal-halide perovskites and offers an investigation methodology useful to characterize charge carrier transport in such emerging semiconductors.

A sub-150-nanometre-thick and ultraconformable solution-processed all-organic transistor.

Recent advancements in the field of electronics have paved the way to the development of new applications, such as tattoo electronics, where the employment of ultraconformable devices is required, typically achievable with a significant reduction in their total thickness. Organic materials can be considered enablers, owing to the possibility of depositing films with thicknesses at the nanometric scale, even from solution. However, available processes do not allow obtaining devices with thicknesses below hundreds of nanometres, thus setting a limit. Here, we show an all-organic field effect transistor that is less than 150 nm thick and that is fabricated through a fully solution-based approach. Such unprecedented thickness permits the device to conformally adhere onto nonplanar surfaces, such as human skin, and to be bent to a radius lower than 1 µm, thereby overcoming another limitation for field-effect transistors and representing a fundamental advancement in the field of ultrathin and tattoo electronics.

A Rapidly Stabilizing Water-Gated Field-Effect Transistor Based on Printed Single-Walled Carbon Nanotubes for Biosensing Applications.

Biosensors are expected to revolutionize disease management through provision of low-cost diagnostic platforms for molecular and pathogenic detection with high sensitivity and short response time. In this context, there has been an ever-increasing interest in using electrolyte-gated field-effect transistors (EG-FETs) for biosensing applications owing to their expanding potential of being employed for label-free detection of a broad range of biomarkers with high selectivity and sensitivity while operating at sub-volt working potentials. Although organic semiconductors have been widely utilized as the channel in EG-FETs, primarily due to their compatibility with cost-effective low-temperature solution-processing fabrication techniques, alternative carbon-based platforms have the potential to provide similar advantages with improved electronic performances. Here, we propose the use of inkjet-printed polymer-wrapped monochiral single-walled carbon nanotubes (s-SWCNTs) for the channel of EG-FETs in an aqueous environment. In particular, we show that our EG-CNTFETs require only an hour of stabilization before producing a highly stable response suitable for biosensing, with a drastic time reduction with respect to the most exploited organic semiconductor for biosensors. As a proof-of-principle, we successfully employed our water-gated device to detect the well-known biotin-streptavidin binding event.

Sweet Electronics: Honey-Gated Complementary Organic Transistors and Circuits Operating in Air.

Sustainable harnessing of natural resources is key moving toward a new-generation electronics, which features a unique combination of electronic functionality, low cost, and absence of environmental and health hazards. Within this framework, edible electronics, of which transistors and circuits are a fundamental component, is an emerging field, exploiting edible materials that can be safely ingested, and subsequently digested after performing their function. Dielectrics are a critical functional element of transistors, often constituting their major volume. Yet, to date, there are only scarce examples of electrolytic food-based materials able to provide low-voltage operation of transistors at ambient conditions. In this context, a cost-effective and edible substance, honey, is proposed to be used as an electrolytic gate viscous dielectric in electrolyte-gated organic field-effect transistors (OFETs). Both n- and p-type honey-gated OFETs (HGOFETs) are demonstrated, with distinctive features such as low voltage (<1 V) operation, long-term shelf life and operation stability in air, and compatibility with large-area fabrication processes, such as inkjet printing on edible tattoo-paper. Such complementary devices enable robust honey-based integrated logic circuits, here exemplified by inverting logic gates and ring oscillators. A marked device responsivity to humidity provides promising opportunities for sensing applications, specifically, for moisture control of dried or dehydrated food.

Organic Electronics Picks Up the Pace: Mask-Less, Solution Processed Organic Transistors Operating at 160 MHz.

Organic printed electronics has proven its potential as an essential enabler for applications related to healthcare, entertainment, energy, and distributed intelligent objects. The possibility of exploiting solution-based and direct-writing production schemes further boosts the benefits offered by such technology, facilitating the implementation of cheap, conformable, bio-compatible electronic applications. The result shown in this work challenges the widespread assumption that such class of electronic devices is relegated to low-frequency operation, owing to the limited charge mobility of the materials and to the low spatial resolution achievable with conventional printing techniques. Here, it is shown that solution-processed and direct-written organic field-effect transistors can be carefully designed and fabricated so to achieve a maximum transition frequency of 160 MHz, unlocking an operational range that was not available before for organics. Such range was believed to be only accessible with more performing classes of semiconductor materials and/or more expensive fabrication schemes. The present achievement opens a route for cost- and energy-efficient manufacturability of flexible and conformable electronics with wireless-communication capabilities.

Cold Crystallization of the Organic n-Type Small Molecule Semiconductor 2-Decyl-7-phenyl-[1]benzothieno[3,2-b][1]benzothiophene S,S,S',S'-Tetraoxide.

The asymmetric n-type Ph-BTBT-C10 derivative 2-decyl-7-phenyl-[1]benzothieno[3,2-b][1]benzothiophene S,S,S',S'-tetraoxide is structurally investigated in the thin film regime. After film preparation by spin coating and physical vapor deposition, a rather disordered structure is observed, with a strong change of its internal degree of order upon heating. At 95 °C, a transition into a layered structure of upright standing molecules without any in-plane order appears, and at 135 °C, crystallization takes place. This phase information is combined with surface morphological studies and charge carrier mobility measurements to describe the structure and thin film transistor applicability of this molecule.

Photo-electrical properties of 2D quantum confined metal-organic chalcogenide nanocrystal films.

Hybrid quantum wells are electronic structures where charge carriers are confined along stacked inorganic planes, separated by insulating organic moieties. 2D quantum-confined hybrid materials are of great interest from a solid-state physics standpoint because of the rich many-body phenomena they host, their tunability and easy synthesis, allowing the creation of material libraries. In addition, from a technological point of view, 2D hybrids are promising candidates for efficient, tunable, low-cost materials impacting a broad range of optoelectronic devices. Different approaches and materials have, therefore, been investigated, with the notable example of 2D metal halide hybrid perovskites. Despite the remarkable properties of such materials, the presence of toxic elements like lead is not desirable in applications and their ionic lattices may represent a limiting factor for stability under operating conditions. Therefore, non-ionic 2D materials made with non-toxic elements are preferable. In order to expand the library of possible hybrid quantum well materials, herein, we consider an alternative platform based on non-toxic, self-assembled, metal-organic chalcogenides. While the optical properties have been recently explored and some unique excitonic characters highlighted, photo-generation of carriers and their transport in these lamellar inorganic/organic nanostructures and critical optoelectronic aspects remain totally unexplored. We hereby report the first investigation on the electrical properties of the air-stable [AgSePh]∞ 2D coordination polymer in the form of nanocrystal (NC) films readily synthesized in situ and at low temperature, compatible with flexible plastic substrates. The wavelength-dependent photo-response of the NC films suggests the possible use of this material as a near-UV photodetector. We therefore built a lateral photo-detector, achieving a sensitivity of 0.8 A W-1 at 370 nm, thanks to a photoconduction mechanism, and a cut-off frequency of ∼400 Hz, and validated its reliability as an air-stable UV detector on flexible substrates.

N-type organic thermoelectrics: demonstration of ZT > 0.3.

The 'phonon-glass electron-crystal' concept has triggered most of the progress that has been achieved in inorganic thermoelectrics in the past two decades. Organic thermoelectric materials, unlike their inorganic counterparts, exhibit molecular diversity, flexible mechanical properties and easy fabrication, and are mostly 'phonon glasses'. However, the thermoelectric performances of these organic materials are largely limited by low molecular order and they are therefore far from being 'electron crystals'. Here, we report a molecularly n-doped fullerene derivative with meticulous design of the side chain that approaches an organic 'PGEC' thermoelectric material. This thermoelectric material exhibits an excellent electrical conductivity of >10 S cm-1 and an ultralow thermal conductivity of <0.1 Wm-1K-1, leading to the best figure of merit ZT = 0.34 (at 120 °C) among all reported single-host n-type organic thermoelectric materials. The key factor to achieving the record performance is to use 'arm-shaped' double-triethylene-glycol-type side chains, which not only offer excellent doping efficiency (~60%) but also induce a disorder-to-order transition upon thermal annealing. This study illustrates the vast potential of organic semiconductors as thermoelectric materials.