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Printing technology holds great potential for resource‐efficient development of electronic devices and circuits. However, even after decades of research, achieving uniformly responding nanowires (NWs) based printed devices is still a challenge. To date, there is no design rule that clearly guides the fabrication of NW ensemble‐based field‐effect transistors (FETs) and the variables that influence device‐level uniformity remain unclear. The lack of fundamental understanding severely limits the large‐scale and very large‐scale integration (LSI and VLSI). Herein this longstanding issue is addressed with a holistic approach that starts with optimization of the synthesis of ZnO NWs, their printing, and further processing to fabricate transistors with uniform responses (e.g., on‐state current, threshold voltage). Monte Carlo simulation based on statistical analysis of printed ZnO NWs is carried out to develop a probabilistic framework that can predict the large‐scale performance of FETs. As a proof of concept, inverter circuits have been developed using printed ZnO NWs based FETs. This work provides a valuable toolkit to handle the stochastic nature of FETs based on printed ZnO NW ensemble, which can be used for neuromorphic integrated circuit in the future. [ABSTRACT FROM AUTHOR]

Organic electronics is an emerging technology that enables the fabrication of devices with low-cost and simple solution-based processes at room temperature. In particular, it is an ideal candidate for the Internet of Things since devices can be easily integrated in everyday objects, potentially creating a distributed network of wireless communicating electronics. Recent efforts allowed to boost operational frequency of organic field-effect transistors (OFETs), required to achieve efficient wireless communication. However, in the majority of cases, in order to increase the dynamic performances of OFETs, masks based lithographic techniques are used to reduce device critical dimensions, such as channel and overlap lengths. This study reports the successful integration of direct written metal contacts defining a 1.4 μm short channel, printed with ultra-precise deposition technique (UPD), in fully solution fabricated n-type OFETs. An average transition frequency as high as 25.5 MHz is achieved at 25 V. This result demonstrates the potential of additive, high-resolution direct-writing techniques for the fabrication of organic electronics operating in the high-frequency regime. [ABSTRACT FROM AUTHOR]

Large area electronics (LAE) with the capability to sense and retain information are crucial for advances in applications such as wearables, digital healthcare, and robotics. The big data generated by these sensor-laden systems need to be scaled down or processed locally. In this regard, brain-inspired computing and in-memory computing have attracted considerable interest. However, suitable architectures have mainly been developed using costly and resource-intensive conventional lithography-based methods. There is a need for the development of innovative, resource-efficient fabrication routes that enable such devices and concepts. Herein, we present ZnO nanowire (NW)-based memristors on a polyimide substrate fabricated by a LAE-compatible and resource-efficient route comprising solution processing and printing technologies. High-resolution "drop-on-demand" and "direct ink write" printers are employed to deposit metallic layers (silver and gold) and a ZnO seed layer, needed for the site-selective growth of ZnO NWs via a low-cost hydrothermal method. The printed memristors show high bipolar resistance switching (ON/OFF ratio >10 3 ) between two nonvolatile states and consistent switching at ultralow voltages (all devices showed switching at amplitudes <200 mV), with the best performing device showing consistent cycled resistance switching over 4 orders of magnitude with SET and RESET voltages of about 71 and -57 mV, respectively. Thus, the presented devices offer reliable high resistance switching at the lowest reported voltage for printed memristors and prove to be competitive with many conventional nanofabrication-based devices. The presented results show the potential printed memristors technology holds for large-area, low-voltage sensing applications such as electronic skin.

A novel and scalable method enabling the integration of dissimilar thin‐film devices for high density and large‐area sensors is demonstrated. The method is validated by integrating CdS/CdTe P‐N thin‐film diodes with poly‐Si thin‐film transistors (TFTs) in an active pixel sensor (APS) scheme. These devices have been used separately in low‐cost and large‐area applications such as liquid‐crystal displays (Poly‐TFTs) and solar cells (CdS/CdTe) and the methods allow a seamless integration that eliminates the use of discrete pixel‐to‐pixel bumping interconnections. APSs, consisting of a cascode TFT amplifier and a CdS/CdTe diode, are evaluated using pulsed light sources under several wavelengths and intensities. The results demonstrated a responsivity increase of >100× for the integrated sensors and well‐defined signal amplitude, as desirable for energy and intensity monitoring. The method enables the use of two dissimilar and remarkable devices in a wide range of applications such as X‐ray imagers, gamma‐ray detectors, and thermal neutron detectors, while offering large‐area and low‐cost compatibility. More importantly, the integrity and reliability of the diodes and TFTs are not affected by the integration process. [ABSTRACT FROM AUTHOR]

Solution‐processable organic semiconductors can serve as the basis for new products including rollable displays, tattoo‐like smart bandages for real‐time health monitoring, and conformable electronics integrated into clothing or even implanted in the human body. For such exciting commercial applications to become a reality, good device performance and uniformity over large areas are necessary. The design of new materials has progressed at an astonishing pace, but accessing their intrinsic, efficient electrical properties in large‐area flexible device arrays is difficult. The development of protocols that allow integration with industrial‐scale processing for high‐throughput manufacturing, without the need to compromise on performance, is the key for transitioning these materials to real‐life applications. In this work, large‐area arrays of organic thin‐film transistors obtained by spray‐coating the high‐mobility polymer indacenodithiophene‐co‐benzothiadiazole (IDTBT) are demonstrated. A maximum charge carrier mobility of 2.3 cm2 V−1 s−1, with a very narrow performance distribution, is obtained over surface areas of 10 cm × 10 cm. The devices retain their electrical properties when bent multiple times and at different curvatures. In addition, large arrays of highly sensitive (0.25% change in mobility for 1% humidity variation), reusable, near‐identical humidity sensors are produced in a one‐step fabrication and calibrated from 0% to 94% relative humidity. [ABSTRACT FROM AUTHOR]

Capability of high-speed and low-cost manufacturing makes the printing techniques a very promising approach for large-area flexible electronics mass manufacturing. Due to fast and intensive technology development, the lack of knowledge about the reliability and lifetime of printed electronics is obvious, requiring further investigation. Especially, the effect of torsional bending on lifetime is a mostly unexplored field of reliability testing. In this article, a torsional bending test of parallel printed silver conductors (0.3-, 0.5-mm pitch) on polymer substrate (polyethylene terephthalate, 125-μm thickness) was conducted and analyzed. According to the experimental results, torsional bending causes wear-out type failures in conductors and the length-to-width (LTW) ratio of the sample’s substrate was observed to have a significant impact on reliability. If the LTW ratio is smaller than 3, the lifetime of printed conductor seems to collapse and samples lasted for approximately only 17 bending cycles on average. Lifetime was improved by increasing the LTW ratio and samples withstood over hundreds of cycles with LTW ratio of higher than 15. However, the distance of a conductor from the edge of the substrate was not observed to have any significant influence on the reliability under torsional bending. [ABSTRACT FROM AUTHOR]

This paper presents the design and experimental characterization of large-area active matrixes on foil for pressure-sensing applications. Front-end circuits based on organic thin-film transistors on a flexible substrate are laminated with a foil hosting screen-printed PDVF-TrFE piezo sensors to create the complete flexible sensing systems with $6 \times 10$ sensing elements on a $16.5~\text {cm} \times 27.5$ cm area. After defining the specifications based on the application scenarios, and designing two different front-end matrixes (A and B), the performance of the sensing surface B has been investigated in simulation. Numerical results show a readout speed of 5 kframe/s and 78.6 dB maximum signal-to-noise ratio with impact forces up to 50 kN. Experiments made with a prototype based on front end A confirm that the system can correctly reconstruct the impact profile of forces up to 50 kN obtained in a drop tower setup. Measurements of the front end circuit B show an input equivalent noise of 451 $\mu \text{V}_{\mathrm {rms}}$ and a 5% settling time of 13.8 $\mu \text{s}$ , both adequate for the specified applications. [ABSTRACT FROM AUTHOR]

This paper proposed simple and accurate threshold voltage ( V TH) extraction techniques, which can be directly adaptable to various semiconductor technologies ranging from deep sub-micron complementary metal-oxide-semiconductor to large-area thin-film transistor devices. These techniques are developed using multiple circuits, namely, a dynamic source follower, an inverter with a diode-connected load and a current mirror topology, which allow a direct determination of V TH. As the proposed techniques are experimented with large-area emerging technologies, which have a stable single type (n-type) transistor, all the designs employed in this work are confined to only n-type transistors for a fair comparison. The semiconductor technologies under consideration are standard complementary metal-oxide-semiconductor (65 and 130 nm) and oxide (indium-gallium-zinc-oxide and zinc-tin-oxide) thin-film transistors. In order to validate the accuracy of the proposed techniques, extracted V TH from these methods are compared against the value from linear transfer characteristics. The resulting relative error is within 5%, reinforcing proposed techniques suitability to different semiconductor technologies ranging from deep sub-micron to large-area transistors. Copyright © 2017 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Spray-deposited nanocrystalline ZnO films are produced in order to establish empirical relationships between synthetic conditions and the density of states as a means of achieving electrostatic control. By varying the spray-pyrolysis deposition conditions, i.e., substrate temperature, precursor concentration, and flow rate, a wide range of exponentially distributed density of localized states profiles and field-effect mobility values ranging over three orders of magnitude (0.02-30 cm² V-1 s-1) are obtained for analysis. It is found that mobility can be controlled by appropriately tuning the shape of the density of states profile, increasing the band tail slope and reducing the band edge concentration of shallow states. Most significantly, it is shown that the shape of the density of states can be modified by adjusting the spray-pyrolysis deposition conditions for electrostatic control. It is found that higher Zn precursor concentration in solution increases the slope of the band tails, leading to higher mobility. Additionally, the band edge concentration is reduced with increased substrate temperature also leading to higher mobility. These results quantify the relationship between defect electrostatics and electron transport while demonstrating electrostatic control via synthetic modification of localized states. [ABSTRACT FROM AUTHOR]

Recent advances in flexible electronics have enabled the development of large-area electronics, which are typically fabricated from petroleum-based polymers. With the rapidly growing market of flexible electronics and sensors, there is a pressure to move toward environmentally friendly products. In this article, a bio-based polyurethane soft elastomeric capacitor for structural health monitoring applications is presented. The sensor’s dielectric is fabricated using castor oil–based waterborne polyurethane, mixed with titanium dioxide, which replaces petroleum-based dielectric materials (e.g. styrene-ethylene/butylene-styrene) previously used by the authors. A critical advantage of the proposed castor oil–based polyurethane over styrene-ethylene/butylene-styrene is the environmentally friendly nature of the bio-based polymer and water-based fabrication process of the dielectric that limits the use of solvents. Static characterization demonstrates the linearity of the sensor and its ability to transduce local strain of large surfaces into change in capacitance. Material test results show good physical and chemical properties, despite a decay of the dielectric that occurs after the first 16 days of fabrication. [ABSTRACT FROM AUTHOR]

A rapid, simple and cost-effective polyol method has been developed for the synthesis of silver nanowires with high aspect ratio and high purity. The aspect ratios of the silver nanowires as high as ca. 1000 (average length 40 µm and some even as long as 80 µm, diameter 50-100 nm) were obtained via optimizing the reaction conditions. Transparent electrodes with excellent optoelectronic performances (optical transmittance of 90%, sheet resistance of 23.2 Ω/□ and optical transmittance of 87%, sheet resistance of 19.7 Ω/□) comparable to commercial ITO were fabricated via simple spin coating the resulting silver nanowires onto the glass substrates. The high optoelectronic performances and the facile all-solution process of the as-prepared transparent electrodes render them rather promising candidates for use in cost-effective large-area optoelectronic devices. [ABSTRACT FROM AUTHOR]

Transparent flexible n-ZnO:Al (100 nm)/ n-ZnO (40 nm)/ p-CuAlO:Ca (100 nm, 200 nm, 300 nm) diodes were fabricated on polyethylene terephthalate substrates at room temperature using a sputtering technique. No additional heat treatment was performed on the fabricated devices. Increase of the diode layer thickness reduced the on-current and leakage-current levels simultaneously, which led the rectification ratio to first increase and then decrease as the p-layer thickness increased. The ultraviolet (UV) response of the diode was also investigated under irradiation at 365 nm. The n-ZnO:Al (100 nm)/ n-ZnO (40 nm)/ p-CuAlO:Ca (200 nm) diode exhibited photocurrent/leakage current ratio of 1.03 × 10 and responsivity of 0.64 A/W at reverse bias of −6 V when measured in flat status. The corresponding photocurrent/leakage current ratio and responsivity were 7.99 × 10 and 0.65 A/W, respectively, for an outwardly bent diode with 5.5 cm radius of curvature. The increases of current levels under bending are attributed to the decreases of series resistance for the diode under tensile strain. [ABSTRACT FROM AUTHOR]

An X-ray photon-quantum-noise-limited voltage-controlled oscillator (VCO)-based pixel architecture in amorphous-silicon (a-Si) technology is reported for large-area digital medical imaging applications. In this research, the X-ray generated input charge on the input capacitor is converted into an oscillating frequency signal output at the pixel level. The VCO pixel is fabricated in-house using a-Si technology, and experimental results are presented. Readout circuitry is proposed which can be optimized to reduce the fixed pattern noise and fringing effects in an imaging array containing many such VCO pixels. The phase noise and stability performance of the single-pixel VCO are measured and analyzed. This architecture has the lowest input referred noise among all reported a-Si pixel architectures and is the first photon-quantum-noise-limited pixel architecture in a-Si technology. The pixel's valid input range is measured to be 120 \e^- all the way to \5 \times \10^6\ \e^-. This shows that the pixel has a very high dynamic range. The proposed architecture is particularly promising for large-area photon-quantum-noise-limited digital imaging applications (e.g., protein crystallography) due to its small input referred electronic noise, high sensitivity, and ease of fabrication in large-area a-Si technology. [ABSTRACT FROM PUBLISHER]

A 100-V ac energy meter based on the system-on- a-film (SoF) concept, in which various devices are integrated on a flexible film, is presented. The system consists of 20-V organic CMOS digital and analog circuits with a floating gate (FG) for process variation compensation, 100-V organic pMOS rectifiers for generating a 50-Hz clock and 20-V dc power, and an organic LED (OLED) bar indicator. The energy meter based on the SoF is flexible and therefore can be installed to monitor each ac outlet simultaneously. The organic devices are printable, and it is expected that they can be formed using a low-cost printing process in the future. The energy meter can measure the accumulated energy of a 100-Vrms ac lineup to a full-scale value of 360 Wh when a 500-W target load is monitored. The flexible film is foldable and its total area excluding the ac connector is 200\,\times\,200 \ mm^2 in the unfolded form or 70\,\times\,70 \ mm^2 when folded. [ABSTRACT FROM PUBLISHER]

In this paper we present User Customizable Logic Paper (UCLP) with a Sea-of Transmission-Gates (SOTG) of 2-V organic CMOS transistors. This can enable users to fabricate custom integrated circuits, by printing 200 \mu\ m wide interconnects with at-home ink-jet printers for the prototyping of large-area electronics and educational purposes. The SOTG reduces the area of the circuits in UCLP by between 11% and 85% compared with a conventional gate array architecture. [ABSTRACT FROM AUTHOR]

By using state-of-the-art printing technologies and functional inks, we have demonstrated organic nonvolatile flexible random-access-memory matrices with a nondestructive read-out capability and a time-continuous current output; these functionalities have not been simultaneously achieved even by silicon-based conventional memory. A memory cell comprising three transistors becomes possible with inkjet printing and other solution-based processes, which can use ferroelectric copolymer ink comprising poly(vinylidenefluoride-co-trifluoroethylene) and insulating ink comprising polyimide precursors properly within the planer plastic substrate. A large "1 : 0" current ratio of 105 is observed in air when it is annealed at 135 °C, which is sufficiently low to be compatible with many plastic substrates. When stored in air, the "1 : 0" ratio was still 104 after 15 days and 10³ after 5 months, which is sufficient for practical applications. Furthermore, human-scale communication sheets were manufactured as the first demonstration utilizing large-area organic memories. [ABSTRACT FROM AUTHOR]

The recent efforts in exploiting semiconductor nanowires (NWs) for high-performance macroelectronics are reviewed. In brief, a new concept of NW thin-film transistors (NW-TFTs) has been proposed and demonstrated from oriented semiconductor NW thin films. In NW-TFTs, the source and drain electrodes are bridged by multiple single-crystal NWs in parallel. Therefore, charges travel from source to drain within single crystals, ensuring high carrier mobility. Recent studies have shown that high-performance NW-TFTs and high-frequency circuits can be produced from silicon NWs on a variety of substrates, including glass and plastics, using a solution assembly process. The device performance of these NW-TFTs not only greatly surpasses that of solution-processed organic TFTs but is also significantly better than that of conventional amorphous or polycrystalline silicon TFTs, approaching single-crystal silicon-based devices. Further- more, with a similar framework, group III-V or II-VI NW or nanoribbon materials of high intrinsic carrier mobility or optical functionality can be assembled into thin films on flexible substrates to enable new multifunctional electronics/optoelectronics that are not possible with traditional macroelectronics. This approach thus opens a new avenue to high-performance flexible macroelectronics and will not only impact existing applications but also enable a whole new generation of flexible, wearable, or disposable electronics for computing, storage, and wireless communication. [ABSTRACT FROM AUTHOR]

A large-area, flexible, and lightweight sheet-type Braille display has been successfully fabricated on a plastic film by integrating high-quality organic transistors and soft actuators. An array of rectangular plastic actuators is mechanically processed from a perfluorinated polymer electrolyte membrane. A small semisphere, which projects upward from the rubberlike surface of the display, is attached to the tip of each rectangular actuator. The effective display size is 4 × 4 cm². Each Braille letter consists of 3 × 2 dots and 24 letters; in other words, 6 letters × 4 lines can be displayed. Pentacene field-effect transistors with top-contact geometry have a channel length of 20 μm and a mobility of 1 cm²/V · s. The Braille dots on one line are driven for 0.9 s. The total thickness and weight of the entire device are I mm and 5.3 g, respectively. The present scheme will enable people with visual impairments to carry the Braille sheet display in their pockets and read Braille e-books at any time. Since all the device components are manufactured on plastic films, these sheet-type Braille displays are mechanically flexible, lightweight, shock resistant, and potentially inexpensive to manufacture; therefore, they are suitable for mobile electronics. [ABSTRACT FROM AUTHOR]

An integrated system of organic FETs (OFETs) and plastic actuators is proposed, and it is applied to a Braille sheet display. Some circuit technologies are presented to enhance the speed and the lifetime for the Braille sheet display. An OFET SRAM is developed to hide the slow transition of the actuators. Developed five-transistor SRAM cell reduces the number of the bit lines by one-half and reduces the SRAM cell area by 20%. Pipelining the write-operation reduced the SRAM write-time by 69%. Threshold voltage control technology using a back gate increased the static noise margin of SRAM and compensated for the chemical degradation of the OFETs after 15 days. The oscillation frequency tuning range from -82% to + 13% in a five-stage ring oscillator is also demonstrated with the threshold voltage control technology. The overdrive techniques for the driver OFETs reduced the transition time of the actuator from 34 s to 2 s. These developed circuit technologies achieved the practical 1.75-s operation to change all 144 Braille dots on Braille sheet display and will be essential for the future large area electronics made with OFETs. [ABSTRACT FROM AUTHOR]

A large-area, flexible, and lightweight sheet image scanner has been successfully manufactured on a plastic film by integrating high-quality organic transistors and organic photodetectors. The effective sensing area of the integrated device is 5 × 5 cm² the resolution, 36 dots per inch (dpi); and the total number of sensor cells, 5184. The pentacene transistors with top contact geometry have a channel length of 18 μm and mobility of 0.7 cm² /Vs. Organic photodetectors composed of copper phthalocyanine and 3,4,9,10-perylene-tetracarboxylic-diimide distinguish between black and white parts on paper based on the difference in their reflectivity. Since this new area-type image-capturing device does not require any optics or mechanical scanning devices, the present sheet image scanners are mechanically flexible, lightweight, shock resistant, and potentially inexpensive to manufacture; therefore, they are suitable for human-friendly mobile electronics. [ABSTRACT FROM AUTHOR]

Conceptual hardware architecture of skin-like circuits is described. An elastomeric skin carries rigid islands on which active subcircuits are made. The subcircuit islands are interconnected by stretchable metallization. We concentrate on recent advances in stretchable thin-film conductors, by covering their construction, evaluation, and laboratory and theoretical analysis. Reversibly stretchable conductors with electrically-critical strains ranging from 10% to 100% have been made. [Copyright &y& Elsevier]

This paper presents fabrication of microelectromechanical systems (MEMS) at low temperatures (100 °C) using thin film silicon technology and their electromechanical characterization. Thin film technology can enable the expansion of MEMS to applications requiring low-temperature fabrication on a CMOS backplane, or on large area and/or flexible substrates. Electrostatic actuation, both in a quasi-DC regime and at the resonance frequency range, of bridge and cantilever structures on glass substrates is described. The resulting movement of the microstructures is characterized using optical, and integrated magnetic and piezoresistive detection. In the quasi-DC regime, control of the actuation of the structures to deflections on the sub-nanometer scale is achieved. Resonance frequencies up to 22 MHz have been measured on hydrogenated amorphous silicon bridges with quality factors up to 100 in air. [Copyright &y& Elsevier]

Solid-state transistor sensors that can detect biomolecules in real time are highly attractive for emerging bioanalytical applications. However, combining upscalable manufacturing with the required performance remains challenging. Here, an alternative biosensor transistor concept is developed, which relies on a solution-processed In 2 O 3 /ZnO semiconducting heterojunction featuring a geometrically engineered tri-channel architecture for the rapid, real-time detection of important biomolecules. The sensor combines a high electron mobility channel, attributed to the electronic properties of the In 2 O 3 /ZnO heterointerface, in close proximity to a sensing surface featuring tethered analyte receptors. The unusual tri-channel design enables strong coupling between the buried electron channel and electrostatic perturbations occurring during receptor-analyte interactions allowing for robust, real-time detection of biomolecules down to attomolar (am) concentrations. The experimental findings are corroborated by extensive device simulations, highlighting the unique advantages of the heterojunction tri-channel design. By functionalizing the surface of the geometrically engineered channel with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) antibody receptors, real-time detection of the SARS-CoV-2 spike S1 protein down to am concentrations is demonstrated in under 2 min in physiological relevant conditions., (© 2021 Wiley-VCH GmbH.)

This letter investigates the influence of a corrugated gate on the transfer characteristics of thin-film transistors. Corrugations that run parallel to the length of the channel from source to drain are patterned on the gate. The author finds that these corrugations result in higher currents as compared to conventional planar-gate transistors. [ABSTRACT FROM PUBLISHER]

The design and implementation of an on-pixel voltage-controlled oscillator for digital imaging applications based on a ring-oscillator circuit fabricated in amorphous silicon thin-film transistor technology is presented. Preliminary results on sensitivity, voltage to frequency gain, linearity, and simulation results of long-term stability appear promising for its application in large-area digital medical X-ray imagers. [ABSTRACT FROM AUTHOR]

Recent advances in solution-processable semiconducting colloidal quantum dots (CQDs) have enabled their use in a range of (opto)electronic devices. In most of these studies, device fabrication relied almost exclusively on thermal annealing to remove organic residues and enhance inter-CQD electronic coupling. Despite its widespread use, however, thermal annealing is a lengthy process, while its effectiveness to eliminate organic residues remains limited. Here, we exploit the use of xenon flash lamp sintering to post-treat solution-deposited layers of lead sulfide (PbS) CQDs and their application in n-channel thin-film transistors (TFTs). The process is simple, fast, and highly scalable and allows for efficient removal of organic residues while preserving both quantum confinement and high channel current modulation. Bottom-gate, top-contact PbS CQD TFTs incorporating SiO 2 as the gate dielectric exhibit a maximum electron mobility of 0.2 cm 2 V -1 s -1 , a value higher than that of control transistors (≈10 -2 cm 2 V -1 s -1 ) processed via thermal annealing for 30 min at 120 °C. Replacing SiO 2 with a polymeric dielectric improves the transistor's channel interface, leading to a significant increase in electron mobility to 3.7 cm 2 V -1 s -1 . The present work highlights the potential of flash lamp annealing as a promising method for the rapid manufacture of PbS CQD-based (opto)electronic devices and circuits.

This Letter presents a technique for implementing circuits with multiple subthreshold swings. Such circuits are of particular interest to large‐area and flexible electronics, including active matrix displays and sensors. In these circuits, devices with large swings may be used for high‐precision analogue driving, whereas steep subthreshold devices may be used for fast and low‐power switching. This Letter demonstrates that large swings may be obtained by the series connection of diode structures to the source terminals of steep subthreshold devices. In principle, this technique is applicable to a wide range of thin‐film transistors, but it is particularly well suited for heterojunction field‐effect transistors where the gate heterojunctions may be readily utilised as diodes without altering the fabrication process or increasing the number of mask steps. Implementation of multiple subthreshold swings is demonstrated experimentally and described by a first‐order model. [ABSTRACT FROM AUTHOR]

Perfectly wrapping planar electronics to complex 3D surfaces represents a major challenge in the manufacture of conformable electronics. Intuitively, thinner electronics are easier to conform to curved surfaces but they usually require a supporting substrate for handling. The water transfer printing (WTP) technology utilizes water surface tension to keep ultrathin electronics floating flat without supporting substrate, enabling their conformal transfer on 3D surfaces through a dipping process. In many cases, however, the size of the microfabricated electronics is much smaller than the target 3D surface. This work proposes that such mismatch in size can be overcome by leveraging stretchable electronics in WTP. Stretchable electronics are compliant to in‐plane stretch induced by water surface tension, hence can first self‐expand in water and then be transferred onto 3D objects. Uniaxial and biaxial expansion ranging from 41% to 166% has been achieved without any externally applied tension. The results demonstrate that expansion‐enhanced WTP is a promising fabrication process for conformable electronics on large 3D surfaces. [ABSTRACT FROM AUTHOR]

In article number 1806002, Rebecca L. Peterson and Youngbae Son report a simple process for simultaneous fabrication of thin film diodes and transistors using selective‐area reactions. In some regions, thermodynamically‐driven redox and diffusion of a molybdenum film during oxide semiconductor deposition forms a rectifying contact, whereas in areas without exposed metal, oxide transistors are made. RF wireless energy harvesting circuits are demonstrated. This work opens the door for future low‐cost, multi‐functional thin film electronics. [ABSTRACT FROM AUTHOR]

Direct additive fabrication of thin‐film electronics using a high‐mobility, wide‐bandgap amorphous oxide semiconductor (AOS) can pave the way for integration of efficient power circuits with digital electronics. For power rectifiers, vertical thin‐film diodes (V‐TFDs) offer superior efficiency and higher frequency operation compared to lateral thin‐film transistors (TFTs). However, the AOS V‐TFDs reported so far require additional fabrication steps and generally suffer from low voltage handling capability. Here, these challenges are overcome by exploiting in situ reactions of molybdenum (Mo) during the solution‐process deposition of amorphous zinc tin oxide film. The oxidation of Mo forms the rectifying contact of the V‐TFD, while the simultaneous diffusion of Mo increases the diode's voltage range of operation. The resulting V‐TFDs are demonstrated in a full‐wave rectifier for wireless energy harvesting from a commercial radio‐frequency identification reader. Finally, by using the same Mo film for V‐TFD rectifying contacts and TFT gate electrodes, this process allows simultaneous fabrication of both devices without any additional steps. The integration of TFTs alongside V‐TFDs opens a new fabrication route for future low‐cost and large‐area thin‐film circuitry with embedded power management. A facile solution processing method is developed that can fabricate vertical thin‐film diodes and lateral thin‐film transistors in a single process. By exploiting in situ redox and diffusion of a bottom molybdenum electrode occurring during semiconductor deposition, the thin‐film diodes achieve high voltage and high‐frequency operation. Furthermore, their use in full‐wave rectifiers is demonstrated for wireless energy harvesting. [ABSTRACT FROM AUTHOR]