Stretchable Microfluidic Radiofrequency Antennas

Highly stretchable and robust antennas are fabricated by injecting liquid metal into a microfluidic channel that consists of two types of silicone rubber with different stiffness. The resulting antennas exhibit high mechanical stability under strain, while retaining high stretchability; these antennas can be stretched by up to a tensile strain of 120% with little degradation in radiation efficiency.Chemistry and Chemical BiologyEngineering and Applied Science

Replacing –CH2CH2- with -CONH- Does Not Significantly Change Rates of Charge Transport Through AgTS-SAM//Ga2O3/EGaIn Junctions

This paper describes physical-organic studies of charge transport by tunneling through self-assembled monolayers (SAMs), based on systematic variations of the structure of the molecules constituting the SAM. Replacing a −CH2CH2– group with a −CONH– group changes the dipole moment and polarizability of a portion of the molecule and has, in principle, the potential to change the rate of charge transport through the SAM. In practice, this substitution produces no significant change in the rate of charge transport across junctions of the structure AgTS-S(CH2)mX(CH2)nH//Ga2O3/EGaIn (TS = template stripped, X = −CH2CH2– or −CONH–, and EGaIn = eutectic alloy of gallium and indium). Incorporation of the amide group does, however, increase the yields of working (non-shorting) junctions (when compared to n-alkanethiolates of the same length). These results suggest that synthetic schemes that combine a thiol group on one end of a molecule with a group, R, to be tested, on the other (e.g., HS∼CONH∼R) using an amide-based coupling provide practical routes to molecules useful in studies of molecular electronics.Chemistry and Chemical Biolog

The Electrical Resistance of AgTS-S(CH2)n-1CH3//Ga2O3/EGaIn Tunneling Junctions

Tunneling junctions having the structure AgTS–S(CH2)n−1CH3//Ga2O3/EGaIn allow physical–organic studies of charge transport across self-assembled monolayers (SAMs). In ambient conditions, the surface of the liquid metal electrode (EGaIn, 75.5 wt % Ga, 24.5 wt % In, mp 15.7 °C) oxidizes and adsorbs―like other high-energy surfaces―adventitious contaminants. The interface between the EGaIn and the SAM thus includes a film of metal oxide, and probably also organic material adsorbed on this film; this interface will influence the properties and operation of the junctions. A combination of structural, chemical, and electrical characterizations leads to four conclusions about AgTS–S(CH2)n−1CH3//Ga2O3/EGaIn junctions. (i) The oxide is ∼0.7 nm thick on average, is composed mostly of Ga2O3, and appears to be self-limiting in its growth. (ii) The structure and composition (but not necessarily the contact area) of the junctions are conserved from junction to junction. (iii) The transport of charge through the junctions is dominated by the alkanethiolate SAM and not by the oxide or by the contaminants. (iv) The interface between the oxide and the eutectic alloy is rough at the micrometer scale.Chemistry and Chemical Biolog

A Ladder-Type Organosilicate Copolymer Gate Dielectric Materials for Organic Thin-Film Transistors

A ladder-type organosilicate copolymer based on trimethoxymethylsilane (MTMS) and 1,2-bis(triethoxysilyl)alkane (BTESn: n = 2–4) were synthesized for use as gate dielectrics in organic thin-film transistors (OTFTs). For the BTESn, the number of carbon chains (2–4) was varied to elucidate the relationship between the chemical structure of the monomer and the resulting dielectric properties. The developed copolymer films require a low curing temperature (≈150 °C) and exhibit good insulating properties (leakage current density of ≈10−8–10−7 A·cm−2 at 1 MV·cm−1). Copolymer films were employed as dielectric materials for use in top-contact/bottom-gate organic thin-film transistors and the resulting devices exhibited decent electrical performance for both p- and n-channel organic semiconductors with mobility as high as 0.15 cm2·V−1·s−1 and an Ion/Ioff of >105. Furthermore, dielectric films were used for the fabrication of TFTs on flexible substrates

Towards Sustainable Urban Spatial Structure: Does Decentralization Reduce Commuting Times?

This paper contributes to the existing debate on the co-location hypothesis, by devising a proximity measure and controlling for a set of other urban form measures. Utilizing the LEHD (Longitudinal Employer–Household Dynamics) Origin-Destination Employment Statistics (LODES) data that provide the number of jobs by a finer geography, this paper measured the degree of centralization, proximity, and job–housing mismatch. Multiple regression analysis revealed that the job–worker proximity leads to a shorter commuting time. In addition, the results focusing on suburban areas revealed that the impact of the job–worker imbalance and the impact of job–worker mismatch on the commuting time are greater in the suburb in comparison with the city center

Long-Duration Transmission of Information with Infofuses

“Infofuse” for long: “Infofuses”—chemically based systems for non-electronic communication that can transmit alphanumeric information encoded as pulses of light (see picture)—can now operate for hours without extinction. These characteristics improve their potential for a new approach to information technology that combines chemistry and information—“infochemistry”.Chemistry and Chemical Biolog

Oligofuran–Benzothiadiazole Co-oligomers: Synthesis, Optoelectronic Properties and Reactivity

Abstract Donor–acceptor–donor (DAD) triad systems are commonly applied as active materials in ambipolar organic field-effect transistors, organic solar cells, and NIR-emitting organic light-emitting diodes. Often, these triads utilize oligothiophenes as donors, whereas their oxygen-containing analogs, oligofurans, are far less studied in this setup. Here we introduce a family of DAD triads in which the donors are oligofurans and the acceptor is benzothiadiazole. In a combined computational and experimental study, we show that these triads display optical bandgaps similar to those of their thiophene analogs, and that a bifuran donor is sufficient to produce emission in the NIR spectral region. The presence of a central acceptor unit increases the photostability of oligofuran-based DAD systems compared with parent oligofurans of the similar length

Squaraine-based polymers. Toward optimized structures for optoelectronic devices

A novel polymer semiconductor based on squaric acid is successfully prepared through poly-condensation reaction. Physicochemical properties of polysquaraine are explored by Fourier transform infrared (FT-IR) and ultraviolet-visible (UV-vis) absorption spectroscopy, thermogravi-metric/modulated temperature differential scanning calorimetry (TGA/MTDSC) analyses, and cyclic voltammetry (CV). Next, the charge carrier properties are investigated through the fab-rication and characterization of field-effect transistors (FETs) using solution-processed polymeric films. It is found that the polysquaraine is FET active and exhibits decent p-type mobili-ties (up to 5 × 10−4 cm2 V−1 s−1), which illustrates the promising properties of this semiconductor in optoelectronics. Notably, there is no precedent for the use of squaraine-based poly-mers in field-effect transistors. Bulk heterojunction solar cells (BHJ-OSCs) are finally prepared from the blends of poly-squaraine with the fullerene derivative [6,6]-phenyl-C71-bu-tyric acid methyl ester (PC71BM). Power conversion efficiencies up to 0.86% are achieved for nonoptimized system under sim-ulated air mass 1.5 (AM1.5) conditions

Synthesis, characterization, and thin-film transistor response of Benzo[i]pentahelicene-3,6-dione

Organic semiconductors hold the promise of simple, large area solution deposition, low thermal budgets as well as compatibility with flexible substrates, thus emerging as viable alternatives for cost-effective (opto)-electronic devices. In this study, we report the optimized synthesis and characterization of a helically shaped polycyclic aromatic compound, namely benzopentahelicene-3,6-dione, and explored its use in the fabrication of organic field effect transistors. In addition, we investigated its thermal, optical absorption, and electrochemical properties. Finally, the single crystal X-ray characterization is reported

Characterization of [1]Benzothieno[3,2-<i>b</i>]benzothiophene (BTBT) Derivatives with End-Capping Groups as Solution-Processable Organic Semiconductors for Organic Field-Effect Transistors

Solution-processable [1]benzothieno[3,2-b]benzothiophene (BTBT) derivatives with various end-capping groups, 2-(phenylethynyl)benzo[b]benzo[4,5]thieno[2,3-d]thiophene (Compound 1), 2-octyl-7-(5-(phenylethynyl)thiophen-2-yl)benzo[b]benzo[4,5]thieno[2,3-d]thiophene (Compound 2), and triisopropyl((5-(7-octylbenzo[b]benzo[4,5]thieno[2,3-d]thiophen-2-yl)thiophen-2-yl)ethynyl)silane (Compound 3), have been synthesized and characterized as active layers for organic field-effect transistors (OFETs). Thermal, optical, and electrochemical properties of the newly synthesized compounds were characterized using thermogravimetric analysis (TGA), a differential scanning calorimeter (DSC), UV–vis spectroscopy, and cyclic voltammetry (CV). Thin films of each compound were formed using the solution-shearing method and the thin film surface morphology and texture of the corresponding films were characterized using atomic force microscopy (AFM) and θ–2θ X-ray diffraction (XRD). All semiconductors exhibited p-channel characteristics in ambient and Compound 1 showed the highest electrical performance with a carrier mobility of ~0.03 cm2/Vs and current on/off ratio of ~106