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To expand and utilize the potential of intermetallic compounds, the importance of quaternary half-Heusler (HH) compounds has attracted attention in the field of thermoelectrics and other inorganic materials research. In this study, triple half-Heusler (THH) Mg2VNi3Sb3 was successfully synthesized by following an unconventional valence balance strategy. X-ray diffraction (XRD) and scanning electron microscope energy dispersive spectroscopy (SEM-EDS) showed the pure and homogeneous nature of samples. Even though both ternary components of Mg2VNi3Sb3, i.e., MgNiSb and VNiSb are expected to be unstable with the metallic transport properties, Mg2VNi3Sb3 possesses semiconducting behavior with Seebeck coefficient peak larger than 115 μV K−1 around 500 K with the small bandgap of 0.12 eV. The lattice thermal conductivity (κL = 2.0 W m−1 K−1) of Mg2VNi3Sb3 is much smaller than κL of conventional half-Heusler and double half-Heusler materials. Since high thermal conductivity has been always a problem for HH materials, the synthesis of THH with low lattice thermal conductivity can be a new direction for developing high-performance HH compounds. Through the synthesis of THH Mg2VNi3Sb3, a new strategy to explore the huge compositional space for further improvement of thermoelectric performance and extended tunability of intermetallic compounds was demonstrated. [ABSTRACT FROM AUTHOR]

The conventional thermoelectric figure of merit and power factor is not sufficient as a measure of thin film quality of thermoelectric materials, where the power conversion efficiency depends on the film dimensions. By considering the film size, the effective thermoelectric figure of merit and effective Seebeck coefficient is introduced to guarantee that the maximum energy conversion efficiency increases as the effective thermoelectric figure of merit increases. Similarly, the effective power factor is defined. By introducing typical material properties for Bi2Te3 and PEDOT, we study the thickness dependence of the effective figure of merit and the effective power factor. [ABSTRACT FROM AUTHOR]

A novel technique of low-energy N2 neutral beam (NB) (<10 eV) irradiation was investigated as a means of controlling the surface nitridation of self-assembled monolayers (SAMs). This low-energy process without UV photons was able to nitride the surfaces of terphenyl SAMs. Furthermore, by varying the on/off period for irradiation, a pulse-time modulated NB process could be used to control the atomic ratio of nitrogen in terphenyl molecules. Time-of-flight secondary ion mass spectra revealed that one H in the terphenyl group was substituted by a NH2 group because of irradiation by the N2 beam. The data suggested that the low-energy NB technique caused less damage to modified surfaces than the conventional plasma process did. Therefore, we believe that it is a potential damage-free process for modifying the surfaces of soft organic materials and films. [ABSTRACT FROM AUTHOR]

Liquid-exfoliation has proven to be a scalable and versatile technique to produce high-yield two-dimensional nanosheets in graphene, BN, layered perovskites and transition metal dichalcogenides. This also provides new insights into the construction of novel nanoelectronics and nanophotonics through the assembly of nanosheets. Here we present a simple exfoliation-and-reassembly approach to produce a flexible n-type TiS2/organic hybrid film for low-temperature thermoelectric applications. The obtained film shows a superlattice structure with alternative layers of TiS2 and organic molecules. Charge transfer occurs when TiS2 and organic molecules form intercalation complexes, which gives rise to a high electrical conductivity but a low Seebeck coefficient. However, the power factor can be further enhanced by annealing the film under vacuum, and the value reaches 210 μW m−1 K−2 at room temperature in this study. Our flexible thermoelectric device can generate a high power density of 2.5 W m−2 at a temperature gradient of 70 K, which hits a new record among organic-based thermoelectric devices. [ABSTRACT FROM AUTHOR]

Molecular multilayers were fabricated using a Ru complex containing Fe cations on an indium tin oxide surface to control the properties of the Ru-complex multilayers such as the multilayer orientation and the electron transport. The Ru-complex multilayer films containing Fe cations were thicker than those containing Zr cations, which have been used previously. The electron transport properties of the multilayers containing Fe cations were evaluated. Solid-state sandwich cell measurements showed that the Ru-complex multilayer films containing Fe cations exhibited increased electron transport with a lower transport coefficient β of 0.01 Å−1, whereas those that contain Zr cations have β∼ 0.07 Å−1. Thus, Fe cations are effective in obtaining thicker Ru-complex layers with increased electron transport abilities. [ABSTRACT FROM AUTHOR]

SUMMARY The electronic structure of fluorinated self-assembled monolayers (F-SAMs) with different chain lengths was investigated by photoelectron and near edge X-ray absorption fine structure (NEXAFS) spectroscopy. From the measurements of the photoelectron spectra in the wide region and in the C 1s core-level region, the chemical compositions and components of the F-SAMs with different chain length were clarified. In the C K-edge NEXAFS spectra of the F-SAMs, the several spectral features were observed and the intensity of the features at 292 eV and 299 eV decreased with increasing incidence angle of the excitation photons. Based on the results of the photoelectron and NEXAFS spectral measurements, the electronic structure of four F-SAMs with different chain length is discussed. [ABSTRACT FROM AUTHOR]

A 'square' binding alignment pattern, with relatively higher energy barrier but four fully aligned orientations at four off-set angles of 0°, 90°, 180°, and 270°, has been analyzed by introducing a concept of the overlap ratio, compared to a 'rectangular' one. Both the 'square-pattern' micro-chips and the substrate with the 'square-pattern' binding sites were fabricated using one-mask micromachining process, and the self-alignment in situ observation under three different off-set orientation angles of 35°, 46°, and 90° was demonstrated using a high-speed video camera. Sequential images reveal a slow translational motion in the early stage followed by a faster rotational alignment. A novel technique has been further proposed for the conductivity evaluation by using three kinds of SAM films, i.e., C12, C18, and Terphenyl. The preliminary measurements indicate that, using the proposed novel structure, the Terphenyl film is believed to be desirable as a conductive SAM film for self-alignment of micro-chips. [ABSTRACT FROM AUTHOR]

There have been numerous studies of liquid crystal (LC) convection using sandwich-type LC cells under AC voltage. In contrast to previous LC convection studies under AC voltage, we propose the use of a binary self-assembled monolayer (SAM) with a redox-active Ru complex and insulating octadecyl phosphonic acid (C18) molecules on an indium tin oxide (ITO) surface as the electrode of sandwich-type LC cells under DC bias voltage. This is because the functionalized molecules immobilized on the ITO surface are expected to control the LC orientation and electrical conduction of LC cells, under an exact DC bias voltage. We successfully achieved LC pattern formation using ITO electrodes with binary SAMs in LC cells. Moreover, we confirmed that the LC pattern size was increased by increasing the coverage of the Ru complex in binary SAMs. We consider that a combination of three factors, electrical conduction change, controlling of LC orientation in the initial stage and redox-activity of the Ru-complex, is the reason for LC convection although we cannot fully explain the distribution of these three factors. We believe that our LC pattern formation is promising for new type devices e.g., artificial compound eyes using the LC device technology. [ABSTRACT FROM AUTHOR]

We have investigated the effect of mixing an alcohol-soluble C60 derivative into a self-assembled monolayer (SAM), which consisted of a redox-active Ru-complex with multipoint anchoring groups, on an indium tin oxide surface. Angle-resolved X-ray photoelectron spectroscopy of the mixed SAM revealed that the C60 derivative was well incorporated into the redox-active Ru-complex SAM. In addition, some of the C60 derivatives were present on the mixed SAM surface. In the presence of a sacrificial reagent, the action spectra of the mixed molecular layer exhibited a broad spectral response due to the presence of the C60 derivative, whereas a sharp response was observed for the monocomponent Ru-complex SAM. We propose that an efficient charge separation arising from the combination of the C60 derivative and the Ru-complex enhanced the spectral response of the mixed SAM. [ABSTRACT FROM AUTHOR]

The protonation/deprotonation response of a novel bipyridine containing (phenylene-ethynylene) thiol adsorbed to a Au surface was investigated with scanning tunneling microscopy (STM). STM results show reversible changes in the average heights (~50 spots) and the height distribution arising from protonation/deprotonation. [ABSTRACT FROM AUTHOR]

This paper describes a 77-GHz three-stage driver amplifier integrated with a very compact 4-dB digital attenuator. The attenuator can provide successful suppression in the gain variation of the amplifier according to ambient temperature in practical use. In addition, the amplifier matching fashion using short stubs and series transmission lines helps suppress unwanted transducer gain and return gain in the out-of band of lower than 77 GHz. The amplifier fabricated in pseudomorphic high electron-mobility technology can deliver a gain of 17.9 dB with an input return loss of 21.0 dB and an output return loss of 22.7 dB in the 77-GHz band, while keeping lower than -16.5 dB of gain in the out-of band. Over the temperature range from -20 °C to 100 °C, the measured results show that a gain variation of less than 2.0 dB is achieved by using the attenuator, while the gain variation without the attenuator is as large as 6.0 dB. The die size is as small as 2.3 × 1.4 mm² due to the very compact attenuator of a 0.2 × 0.6 mm² occupied area. [ABSTRACT FROM AUTHOR]

Oligo(para-phenylene-vinylene)-methanethiol of trimer and dimer have been synthesized to prepare monolayers onto Au(111). The trimer diluted in dichloromethane glows with a brilliant blue fluorescence when excited with UV light (365 nm). The absorption and emission spectra of the dimer diluted in CH[sub 2]Cl[sub 2] show a blue shift. The molecular level morphologies of the monolayers prepared on gold surfaces were probed by scanning tunneling microscopy or atomic force microscopy (AFM). The dimer is entire trans isomer, which formed highly ordered self-assembled monolayers (SAMs) on Au. The trimer is a mixture of cis–trans isomers, and did not form ordered monolayers on Au. However, the trimer molecules could be embedded in dodecanethiol SAM, and showed higher conductance than oligo(para-phenylene) molecules characterized using a conductive AFM. [ABSTRACT FROM AUTHOR]

Presents a study which looked at the performance of V-band monolithic high electron-mobility transistor (HEMT) oscillators. Oscillation characteristics on drain bias; Functions of oscillators; Comparison of the oscillation performance of several gallium arsenide pseudomorphic high electron-mobility transistor (pHEMT) based oscillators.

Damage-free surface nitridation of terphenyl methanethiol self-assembled monolayers (TP1-SAMs) was investigated using a novel low-energy N2 neutral beam (NB) irradiation technique. When a conventional inductively coupled plasma process was used, x-ray photoelectron spectra confirmed that the TP1-SAM was quickly broken because ions or ultraviolet (UV) photons enhance the surface decomposition and molecular desorption. Conversely, with the N2 NB radiation process, which is free of ions and UV photons, there was little difference in the atomic ratios of x-ray photoelectron spectra before and after NB irradiation. These results suggest that low-damage surface modification is possible through the authors’ NB technique. [ABSTRACT FROM AUTHOR]

We report an increase in the thermoelectric power factor of poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) from 23 ± 5 to 225 ± 130 µW/(m·K2) in high-humidity conditions. This enhancement was caused mainly by an increase in the apparent Seebeck coefficient, which could be related to morphological change after water absorption or electrochemical reaction of PEDOT in air. Our results demonstrate a positive effect of water in the PEDOT:PSS system and indicate the need for well-controlled measurement conditions, particularly humidity, in evaluating the performance of conducting organic materials. [ABSTRACT FROM AUTHOR]

Phenylene ethynylene dithiol derivatives containing a bipyridine ligand along the conjugated system were introduced between nanogap electrodes, and significant conductance changes of the bridging molecules were observed upon complexation with Pd(II). [ABSTRACT FROM AUTHOR]