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Sol–gel‐based solution‐processed metal oxides have emerged as a key fabrication method for applications in thin film transistors both as a semiconducting and a dielectric layer. Here, a low‐temperature, green solvent‐based, non‐toxic, and cost‐effective solution shearing approach for the fabrication of thin aluminum oxide (AlOx) dielectrics is reported. Optimization of sustainability aspects like energy demand, and selection of chemicals used allows to reduce the environmental impact of the life cycle of the resulting product already in the design phase. Using this approach, ultra‐thin, device‐grade AlOx films of 7 nm are coated—the thinnest films to be reported for any solution‐fabrication method. The metal oxide formation is achieved by both thermal annealing and deep ultra‐violet (UV) light exposure techniques, resulting in capacitances of 750 and 600 nF cm−2, respectively. The structural analysis using microscopy and x‐ray spectroscopy techniques confirmed the formation of smooth, ultra‐thin AlOx films. These thin films are employed in organic field‐effect transistors (OFETs) resulting in stable, low hysteresis devices leading to high mobilities (6.1 ± 0.9 cm2 V−1 s−1), near zero threshold voltage (−0.14 ± 0.07 V) and a low subthreshold swing (96 ± 16 mV dec−1), enabling device operation at only ±0.5 V with a good Ion/Ioff ratio (3.7 × 105). [ABSTRACT FROM AUTHOR]

Here, the effect of thermal annealing (TA) on the stability of solution‐sheared thin films of the semiconducting polymer poly[2,5‐bis(2‐octyldodecyl)pyrrolo[3,4‐c]pyrrole‐1,4(2H,5H)‐dione‐3,6‐diyl)‐alt‐(2,2′;5′,2′';5′',2′"‐quaterthiophen‐5,5′"‐diyl)] (PDPP4T) against the original coating solvent is studied, and it is shown that TA significantly improves the solvent resistance of semiconducting polymer films. Specifically, after the thin films are annealed at or above a critical temperature, the thin film thickness is largely retained when exposed to the original solvent, while for lower annealing temperatures material loss occurs, i.e., the thin film thickness is reduced due to rapid dissolution. The results of various techniques including grazing‐incidence wide‐angle x‐ray scattering (GIWAXS), atomic force microscopy (AFM), and ultraviolet‐visible‐near infrared (UV–vis‐NIR) absorption spectroscopy suggest physical changes as the cause for the increased solvent resistance. Such annealed films also show stable electrical characteristics in bottom‐gate, top‐contact (BGTC) organic field‐effect transistors (OFETs) even after solvent exposure. In initial tests, a multitude of technologically relevant polymers show such behavior, underlining the potential impact of such temperature treatments for the fabrication of multi‐layer polymer devices. [ABSTRACT FROM AUTHOR]

Conjugated polymers often show efficient charge carrier transport along their backbone which is a primary factor in the electrical behavior of Organic Field Effect Transistor (OFETs) devices fabricated from these materials. Herein, a solution shearing procedure is reported to fabricate micro/nano wires from a diketopyrrolopyrrole (DPP)‐based polymer. Millimeter to nanometer long polymer wires orientated in the coating direction are developed after a thorough analysis of the deposition conditions. It shows several morphological regimes—film, transition, and wires and experimentally derive a phase diagram for the parameters coating speed and surface energy of the substrate. The as‐fabricated wires are isolated, which is confirmed by optical, atomic force, and scanning electron microscopy. Beside the macroscopic alignment of wires, cross‐polarized optical microscopy images show strong birefringence suggesting a high degree of molecular orientation. This is further substantiated by polarized UV‐Vis‐NIR spectroscopy, selected area electron diffraction transmission electron microscopy, and grazing‐incidence wide‐angle X‐ray scattering. Finally, an enhanced electrical performance of single wire OFETs is observed with a 15‐fold increase in effective charge carrier mobility to 1.57 cm2 V−1 s−1 over devices using films (0.1 cm2 V−1 s−1) with similar values for on/off current ratio and threshold voltage. [ABSTRACT FROM AUTHOR]

Synthetic insecticides are widely used against plant pest insects to protect the crops. However, many insecticides have poor selectivity and are toxic also to beneficial insects, animals, and humans. In addition, insecticide residues can remain on fruits for many days, jeopardizing food safety. For these reasons, a reusable, low‐cost electronic trap that can attract, detect, and identify, but attack only the pest while leaving beneficial insects unharmed could provide a sustainable, nature‐friendly replacement. Here, for the first time, research results are presented suggesting the great potential and compatibility of organic electronic devices and technologies with pest management. Electrical characterizations confirm that an insect's body has relatively high dielectric permittivity. Adaptive memcapacitor circuits can track the impedance change for insect detection. Other experiments show that printed polymer piezoelectric transducers on a plastic substrate can collect information about the weight and activity of insects for identification. The breakdown voltage of most insects´ integument is measured to be <200 V. Long channel organic transistors easily work at such high voltages while being safe to touch for humans thanks to their inherent low current. This feasibility study paves the way for the future development of organic electronics for physical pest control and biodiversity protection. [ABSTRACT FROM AUTHOR]

Capacitive analogues of semiconductor diodes (CAPodes) present a new avenue for energy‐efficient and nature‐inspired next‐generation computing devices. Here, we disclose the generalized concept for bias‐direction‐adjustable n‐ and p‐CAPodes based on selective ion sieving. Controllable‐unidirectional ion flux is realized by blocking electrolyte ions from entering sub‐nanometer pores. The resulting CAPodes exhibit charge‐storage characteristics with a high rectification ratio (96.29 %). The enhancement of capacitance is attributed to the high surface area and porosity of an omnisorbing carbon as counter electrode. Furthermore, we demonstrate the use of an integrated device in a logic gate circuit architecture to implement logic operations ('OR', 'AND'). This work demonstrates CAPodes as a generalized concept to achieve p‐n and n‐p analogue junctions based on selective ion electrosorption, provides a comprehensive understanding and highlights applications of ion‐based diodes in ionologic architectures. [ABSTRACT FROM AUTHOR]

Organic phototransistors can enable many important applications such as nonvolatile memory, artificial synapses, and photodetectors in next‐generation optical communication and wearable electronics. However, it is still a challenge to achieve a big memory window (threshold voltage response ∆Vth) for phototransistors. Here, a nanographene‐based heterojunction phototransistor memory with large ∆Vth responses is reported. Exposure to low intensity light (25.7 µW cm−2) for 1 s yields a memory window of 35 V, and the threshold voltage shift is found to be larger than 140 V under continuous light illumination. The device exhibits both good photosensitivity (3.6 × 105) and memory properties including long retention time (>1.5 × 105 s), large hysteresis (45.35 V), and high endurance for voltage‐erasing and light‐programming. These findings demonstrate the high application potential of nanographenes in the field of optoelectronics. In addition, the working principle of these hybrid nanographene‐organic structured heterojunction phototransistor memory devices is described which provides new insight into the design of high‐performance organic phototransistor devices. [ABSTRACT FROM AUTHOR]

Metal oxide (MO) semiconductors are widely used in electronic devices due to their high optical transmittance and promising electrical performance. This work describes the advancement toward an eco‐friendly, streamlined method for preparing thin‐film transistors (TFTs) via a pure water‐solution blade‐coating process with focus on a low thermal budget. Low temperature and rapid annealing of triple‐coated indium oxide thin‐film transistors (3C‐TFTs) and indium oxide/zinc oxide/indium oxide thin‐film transistors (IZI‐TFTs) on a 300 nm SiO2 gate dielectric at 300 °C for only 60 s yields devices with an average field effect mobility of 10.7 and 13.8 cm2 V−1 s−1, respectively. The devices show an excellent on/off ratio (>106), and a threshold voltage close to 0 V when measured in air. Flexible MO‐TFTs on polyimide substrates with AlOx dielectrics fabricated by rapid annealing treatment can achieve a remarkable mobility of over 10 cm2 V−1 s−1 at low operating voltage. When using a longer post‐coating annealing period of 20 min, high‐performance 3C‐TFTs (over 18 cm2 V−1 s−1) and IZI‐TFTs (over 38 cm2 V−1 s−1) using MO semiconductor layers annealed at 300 °C are achieved. [ABSTRACT FROM AUTHOR]

Abstract: Low‐voltage organic field‐effect transistors (OFETs) are of great interest for organic electronics applications that require low power consumption such as wearable electronics, biomedical applications, or mobile electronics. In this work, an approach leading to transistors fabricated from solution with high charge carrier mobilities operating at voltages < 1 V is presented. By blending the small‐molecule semiconductor 6,13‐bis(triisopropylsilyl‐ethynyl)pentacene (TIPS‐pentacene) with polystyrene it is possible to achieve good film coverage and uniformity as well as ultrathin semiconductor films. This reduction in thickness relative to neat films results in a high fraction of the high‐mobility polymorph of TIPS‐pentacene and excellent film morphologies with continuous highly crystalline domains. OFETs using SiO2 as the dielectric with average hole mobilities as high as 8.3 cm2 V−1 s−1 and maximum mobilities of up to 12.3 cm2 V−1 s−1 which favorably compares with the previous record for TIPS‐pentacene, especially when considering the simplicity of the approach, are demonstrated. By depositing the optimized semiconductor blends on solution‐based polymer dielectric layers of polyvinylphenol, cross‐linked with 4,4′‐(hexafluoroisopropylidene)diphthalic anhydride, a record‐high mobility of 4.2 cm2 V−1 s−1 for solution‐processed, ultralow‐voltage OFET devices (operating at <1 V) is obtained. [ABSTRACT FROM AUTHOR]

Abstract: Organic field‐effect transistors based on aligned small molecule semiconductors have shown high charge carrier mobilities in excess of 10 cm2 V−1 s−1. This makes them a viable alternative to amorphous inorganic semiconductors especially if a high reproducibility can be achieved. Here, the optimization of high mobility organic field‐effect transistors based on the organic semiconductor 2,7‐dioctyl[1]benzothieno[3,2‐b] benzothiophene (C8‐BTBT) via the addition of a polymer additive to the printing solution is reported. Specifically, films and devices are compared based on solutions of the neat semiconductor and the blend with polystyrene and shear‐coated devices with excellent device characteristics and gate‐voltage‐independent mobility values reaching 12 cm2 V−1 s−1 are shown, which are the highest reported values for C8‐BTBT‐based films prepared by a scalable, solution‐based process. [ABSTRACT FROM AUTHOR]

In this paper, the design of the chipless-Radio Frequency Identification (RFID) tags based on genetic algorithm (GA) optimization techniques is introduced. The GA is applied for the first time to create a family of frequency-domain chipless tags with a quick responselike appearance. The resultant tags have an area of 30 mm $\times $ 30 mm and consist of a grid of small metallic elements arranged arbitrarily over a $60 \times 60$ element array creating a variety of new structures. The frequency signature of the GA-based tags is optimized to fit with a frequency-shift keying-based coding methodology and a capacity of 8 b is achieved. The performance of the resultant tags is experimentally verified. Optimal tag samples are fabricated using silver-ink, low-cost flexible substrates, and by screen printing, which is a mass-compatible production technique. The feasibility of this optimization technique for the design of chipless-RFID tags is corroborated. [ABSTRACT FROM PUBLISHER]

In this paper, octagonal chipless RFID tags are introduced and herein, the design development, the applied fabrication, and the experimental verification are presented. The designed tags, which are based on frequency-selective surfaces, are produced by screen printing on low-cost flexible materials including plastic and paper. A novel codification technique specifically conceived to complement the high yield manufacturing processes is proposed. Through an extensive measurement campaign, the octagonal chipless RFID tag functionality is proved. The experimental results include the morphological characterization, ID code verification, and a complete study of the bending and folding effects on the tag. Focusing on this, a working bent tag with a curvature radius down to 16 mm is reviewed. Additional characteristics like the polarization independence and extended read ranges are also corroborated. [ABSTRACT FROM AUTHOR]

ABSTRACT Fully mass printed, flexible and truly polymeric organic field effect transistors consisting of a three layer dielectric made of CYTOP (low-k), PVA (intermediate) and P(VDF-TrFE-CTFE)(high-k) are introduced. Gravure-, flexo-and screen printing were selected as highly productive manufacturing technologies. These OFETs work at strongly reduced voltages and show high field effect mobility (µ = 0.2 cm2/Vs) and remarkable good bias stress stability at very high current density (50 µA/mm). Fully printed OFETs are used for the realization of ring oscillators working in the kHz regime at reduced supply voltage (10 V). In combination with printed fully polymeric piezoelectric loudspeakers, this work shows for the first time fully printed flexible audio systems. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2015, 53, 1409-1415 [ABSTRACT FROM AUTHOR]

With the prospect of realizing innovative technologies by large‐area fabrication at low cost and high throughput, printing and coating technologies are being intensively researched for the deposition of functional films. One promising coating technology is solution shearing, which has been studied as a deposition technique for organic semiconductors but not to a greater extent for dielectric layers. Therefore, the deposition by solution shearing of high‐quality poly(4‐vinylphenol) dielectrics is investigated, and the utility of these films as ultra‐smooth dielectric substrates for transistors is demonstrated. By comparing these films to those prepared by spin‐coating, it is possible to highlight the advantages of the technique. Specifically, thinner films with thicknesses as low as 11.4 nm but still low leakage and almost identical surface properties can be achieved. Thus, dielectric films with a very high capacitance of 280 nF cm‐2 are realized in a single coating step. Probing these films within organic transistors shows that they can facilitate operation at voltages as low as ‐1 V. Finally, it is shown how the use of a polymer‐small‐molecule–semiconductor blend can pave the way toward high‐performance, ultra‐low‐voltage devices from solution. [ABSTRACT FROM AUTHOR]

All-polymer, semi-transparent, three-layer-dielectric (3L) organic field effect transistors (OFETs) are fabricated on polyethylene terephthalate plastic substrate, using high-throughput printing techniques. Analog small-signal characteristics of the 3L OFET are presented and are compared against the previous version of this technology, which was based on a single-layer dielectric and a metal gate electrode. The 3L transistor withstands 50 V, can continuously drive 50 μA/mm, reaches an excellent intrinsic-gain ( A v0 ) of 43 dB, an equivalent mobility of 0.85 cm 2 /V, and a transit frequency ( f T ) of 68 kHz, well suited for applications such as driving printed piezoelectric loudspeakers and flexible audio systems. The effects of the relaxor-ferroelectric high-k layer in the 3L stack on the gate capacitance, g m , and A v0 are measured in the frequency domain. In addition, it is observed that PEDOT:PSS makes a better interface with polymer dielectric comparing to copper particle ink. Five-hour small- and large-signal bias stress tests are performed. A novel direct A v0 measurement technique, and an improved transconductance extraction method are also presented. [ABSTRACT FROM AUTHOR]