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Multifunctional smart windows are successfully fabricated by assembling inkjet printed CeO2/TiO2 and WO3/poly(3,4-ethylenedioxythiophene)-poly(styrene sulfonate) films as the anode and cathode, respectively. Large optical modulation (more than 70% at 633 nm), fast switching (12.7/15.8 s), high coloration efficiency (108.9 cm2 C−1), and excellent bistability are achieved by the assembled smart windows. The multifunctional smart window not only can be used as typical electrochromic window, which can change its color to dynamically control the solar radiation transmittance through windows or protect privacy during the day, but also can be used as energy-storage device simultaneously. The designed smart window releases the stored energy to light the bulbs and power other electronic devices at night while its color gradually reverts to transparent state. Moreover, the level of stored energy can be monitored via the visually detectable reversible color variation of the window. The fascinating multifunctional smart windows exhibit promising features for a wide range of applications in buildings, airplanes, automobiles, etc. [ABSTRACT FROM AUTHOR]

Silver grids are attractive for replacing indium tin oxide as flexible transparent conductors. This work aims to improve the electrochemical stability of silver-based transparent conductors. A silver grid/PEDOT:PSS hybrid film with high conductivity and excellent stability is successfully fabricated. Its functionality for flexible electrochromic applications is demonstrated by coating one layer of WO3 nanoparticles on the silver grid/PEDOT:PSS hybrid film. This hybrid structure presents a large optical modulation of 81.9% at 633 nm, fast switching, and high coloration efficiency (124.5 cm2 C−1). More importantly, an excellent electrochemical cycling stability (sustaining 79.1% of their initial transmittance modulation after 1000 cycles) and remarkable mechanical flexibility (optical modulation decay of only 7.5% after 1200 compressive bending cycles) is achieved. A novel smart supercapacitor is presented that functions as a regular energy-storage device and simultaneously monitors the level of stored energy by a rapid and reversible color variation even at high current charge/discharge conditions. The film sustains an optical modulation of 87.7% and a specific capacitance of 67.2% at 10 A g−1 compared to their initial value at a current density of 1 A g−1. The high-performance silver grid/PEDOT:PSS hybrid transparent films exhibit promising features for various emerging flexible electronics and optoelectronic devices. [ABSTRACT FROM AUTHOR]

Abstract: A study of the contact resistance (R sd) in pentacene-based double-gate transistors is presented. In top-contact transistors, as the negative bias of the additional top-gate bias is increased, R sd decreases by over five orders of magnitude for small bottom-gate voltages. In bottom-contact transistors, R sd is reduced by about ten times for all bias values, implying improved charge transport in all operating regimes. The different tunability of R sd in top/bottom-contact transistors is attributed to different charge injection modulation by the coplanar/staggered top gate. Therefore, double-gate architecture offers a novel and effective approach to limit R sd and its relevant impacts on organic transistor. [Copyright &y& Elsevier]

We describe the mechanism of contact resistance reduction and improvement in device performance of organic field-effect transistors by chemical doping at the contact interface. Insertion of iron(III)trichloride into the contact interface significantly reduced the contact resistance from 200 to 8.8 kΩ cm at a gate voltage of -40 V, and a field-effect mobility of 7.0 cm2/V s was achieved in devices based on dioctylbenzothienobenzothiophene. The improved charge injection is attributable to a reduction in the depletion layer thickness at the contact interface and occupation of trap states in the access region due to the generation of charge carriers by contact doping. [ABSTRACT FROM AUTHOR]

The enhancement of the charge injection process by the insertion of an ultrathin (∼1 nm) contact oxide interlayer (COI) at the metal/organic material interface in organic field effect transistors (OFETs) is reported. Six different oxides were used as COI, and Al2O3 was found to exhibit the highest OFET mobility with a reduction in the average contact resistance (Rc) from 19.9 to 1.9 kΩ·cm. Photoelectron yield spectroscopy analysis revealed that the insertion of COI increases the work function of an Au contact and reduces the charge injection barrier at the interface, which lowers Rc and, therefore, results in enhanced device performance. [ABSTRACT FROM AUTHOR]

A novel electrochromo‐supercapacitor based on a stable hybrid transparent conductive electrode is demonstrated by Pooi See Lee and co‐workers in article number 1501882. The bifunctional device performs as a regular energy storage device and simultaneously monitors the level of stored energy with a rapid and reversible color variation, even in high current charge/discharge conditions. [ABSTRACT FROM AUTHOR]

We propose the use of indium tungsten oxide (IWO) as a channel material for thin-film transistors (TFTs). In the present study, an IWO film was deposited at room temperature by means of DC magnetron sputtering and then annealed at 100 °C in N2 prior to formation of Au source and drain electrodes. Analysis using X-ray diffraction and transmission electron microscopy revealed that the film remained amorphous even after the post-deposition annealing treatment. TFTs fabricated using a Si substrate as a back-gate electrode showed good performance, with a saturation field-effect mobility of 19.3 cm2 · V-1 · s-1, an on/off current ratio of 8.9 × 109. [ABSTRACT FROM AUTHOR]

Joule's law opens a straightforward way to explore the operating mechanism of organic field-effect transistors, from the angle of inner transported heating. The microscopic dissipated power is calculated from the local conductivity and electric field, which solves the widespread difficulties in building a macroscopic model to determine the contact resistance. The result quantitatively discloses the correlation between the contact resistance and the charge transport properties covering energetic disorder, band-like and hopping transport as well as carrier mobility anisotropy. It turns out that in a staggered configuration with ideal Ohmic contact, the contact resistance is highly affected by the charge transport. [ABSTRACT FROM AUTHOR]

In this work, a facile method to deposit fast growing electrochromic multilayer films with enhanced electrochemical properties using layer-by-layer (LbL) self-assembly of complex polyelectrolyte is demonstrated. Two linear polymers, poly(acrylic acid) (PAA) and polyethylenimine (PEI), are used to formulate stable complexes under specific pH to prepare polyaniline (PANI)/PAA-PEI multilayer films via LbL deposition. By introducing polymeric complexes as building blocks, [PANI/PAA-PEI]n films grow much faster compared with [PANI/PAA]n films, which are deposited under the same condition. Unlike the compact [PANI/PAA]n films, [PANI/PAA-PEI]n films exhibit porous structure that is beneficial to the electrochemical process and leads to improved electrochromic properties. An enhanced optical modulation of 30% is achieved with [PANI/PAA-PEI]30 films at 630 nm compared with the lower optical modulation of 11% measured from [PANI/PAA]30 films. The switching time of [PANI/PAA-PEI]30 films is only half of that of [PANI/PAA]30 films, which indicates a faster redox process. Utilizing polyelectrolyte complexes as building blocks is a promising approach to prepare fast growing LbL films for high performance electrochemical device applications. [ABSTRACT FROM AUTHOR]

Highlights: [•] Optimal contacts should have smallest size but possess minimum contact effects. [•] Six times of semiconductor film thickness is found to be optimal for contact length. [•] It increases in nanoscale channels with more hopping and anisotropic transport. [•] This optimal contact length is independent of semiconductors and variable mobility. [ABSTRACT FROM AUTHOR]

A method for patterning organic single-crystal transistor arrays via surface selective deposition is presented. Solvent-vapor annealing is applied for the formation of organic crystals under ambient conditions. The devices are fabricated with a dual-gate structure, which allows the investigation of device performances of bottom-gate/top-contact (BG/TC) and top-gate/top-contact (TG/TC) structures based on the same crystals. The resulting BG/TC devices exhibit the field-effect mobility (μFET) up to 3.5 cm2/Vs. And μ FET is influenced by the contact resistance, resulting in large variation in device performance. On the other hand, TG/TC structure exhibits better performance with smaller variation. The highest μ FET is 7.4 cm2/Vs. [ABSTRACT FROM PUBLISHER]

Abstract: Large surface roughness is a major obstacle for electronic systems fabricated on paper substrates. Here, a mixture solution of organic semiconductor and polymer dielectric was spin-coated on paper substrate with a patterned wettability. This spin-coating process produced organic crystals and a very smooth semiconductor/dielectric interface with a low trap density in well-confined patterns. Despite the large roughness of the paper substrate, the fabricated transistor arrays exhibited high performance with a field-effect mobility reaching 1.3cm2/Vs and an on/off ratio of 108. The presented results offer a simple fabrication method for the current rapidly developing technology of paper electronics. [Copyright &y& Elsevier]

Abstract: Solution-processed organic crystals are important in field-effect transistors because of their highly ordered molecular packing and ease of device fabrication. For practical applications, the patterning of organic crystal transistor arrays is critical. However, uniformity, which concerns the variation in electrical performance among devices fabricated simultaneously on the same substrate, is a common consideration in the commercial applications of the solution-processed organic crystal transistor arrays. Here, a simple approach for fabricating field-effect transistor arrays based on organic plate-like crystals is reported. Through this method, a direct spin-coating process from a mixture solution of organic semiconductor and polymer dielectric can produce organic plate-like crystals. The grain size of the crystals is observed to be hundreds of micrometers. By controlling the concentrations of the active materials, the transistor arrays exhibit high uniformity and good device performance. The results presented in this work promise that this approach is a comparable technology to hydrogenated amorphous silicon-based FETs and is a great candidate for practical applications in electronic devices. [Copyright &y& Elsevier]

Porous polymeric layer‐by‐layer self‐assembled films with enhanced electrochromism are demonstrated by P. S. Lee and co‐workers on page 401 using polyaniline and polymeric complexes as building blocks. These films show fast growing behavior as well as enhanced optical modulation and fast switching speed. This image portrays the facilitated diffusion of ions into the porous films during the redox reaction. [ABSTRACT FROM AUTHOR]