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The neutral cluster beam deposition (NCBD) method has been applied to produce and characterize organic thin-film transistors (OTFTs) based upon tetracene and pentacene molecules as active layers. Organic thin films were prepared by the NCBD method on hexamethyldisilazane (HMDS)-untreated and -pretreated silicon dioxide (SiO2) substrates at room temperature. The surface morphology and structures for the tetracene and pentacene thin films were examined by atomic force microscopy (AFM) and X-ray diffraction (XRD). The measurements demonstrate that the weakly bound and highly directional neutral cluster beams are efficient in producing high-quality single-crystalline thin films with uniform, smooth surfaces and that SiO2 surface treatment with HMDS enhances the crystallinity of the pentacene thin-film phase. Tetracene- and pentacene-based OTFTs with the top-contact structure showed typical source-drain current modulation behavior with different gate voltages. Device parameters such as hole carrier mobility, current on/off ratio, threshold voltage, and subthreshold slope have been derived from the current-voltage characteristics together with the effects of surface treatment with HMDS. In particular, the high field-effect room-temperature mobilities for the HMDS-untreated OTFTs are found to be comparable to the most widely reported values for the respective untreated tetracene and pentacene thin-film transistors. The device performance strongly correlates with the surface morphology, and the structural properties of the organic thin films are discussed.

Glycans, which decorate cell surfaces, play crucial roles in various physiological events involving cell surface recognition. Despite the importance of surface glycans, most analyses have been performed using total cells or whole membranes rather than plasma membranes due to difficulties related to isolation. In the present study, we employed an adhesion-based method for plasma membrane isolation to analyze N-glycans on cell surfaces. Cells were attached to polylysine-coated glass plates and then ruptured by hypotonic pressure. After washing to remove intracellular organelles, only a plasma membrane fraction remained attached to the plates, as confirmed by fluorescence imaging using organelle-specific probes. The plate was directly treated with trypsin to digest and detach the glycoproteins from the plasma membrane. From the resulting glycopeptides, N-glycans were released and analyzed using MALDI-TOF mass spectrometry and HPLC. When N-glycan profiles obtained by this method were compared to those by other methods, the amount of high-mannose type glycans mainly contaminated from the endoplasmic reticulum was dramatically reduced, which enabled the efficient detection of complex type glycans present on the cell surface. Moreover, this method was successfully used to analyze the increase of high-mannose glycans on the surface as induced by a mannosidase inhibitor treatment.

Herein is presented systematic analysis of air-stable, ambipolar heterojunction-based organic light-emitting field-effect transistors (OLEFETs). Top-contact OLEFETs with multidigitated, long channel-width geometry were produced by the successive deposition of electron-transporting N,N′-ditridecylperylene-3,4,9,10-tetracarboxylic diimide (P13) and hole-transporting tetracene layers, using the neutral cluster beam deposition (NCBD) method. The morphological, structural, and photoluminescence properties of the untreated and thermally post-treated P13/tetracene active layers were examined by atomic force microscopy, X-ray diffraction, and laser scanning confocal microscopy. From the comparative analysis of the NCBD thin films, the neutral cluster beams led to the preparation of smooth, uniform bilayer films consisting of well-packed grain crystallites. The OLEFETs demonstrated good field-effect characteristics, stress-free operational stability, and electroluminescence under ambient conditions. The operating conduction mechanism that accounts for the observed light emission is also discussed.

Air-stable, ambipolar heterojunction-based organic light-emitting field-effect transistors (OLEFETs) with a top-contact, multidigitated, long-channel geometry were produced, and the current–voltage–light emission (I–V–L) characteristics were systematically examined. Two active layers of p-type pentacene and n-type N,N′-ditridecylperylene-3,4,9,10-tetra carboxylic diimide (P13) as well as a protecting layer of 2,5-bis(4-biphenyl) thiophene (BP1T) were successively deposited using the neutral cluster beam deposition method. On the basis of the growth of high-quality, well-packed crystalline thin films, the OLEFETs demonstrated good field-effect characteristics, well-balanced ambipolarity, operational stability, and electroluminescence (EL) under ambient conditions. The operating conduction and EL mechanisms responsible for the observed recombination zone are discussed with the aid of light-emission images obtained using a charge-coupled device.

Realization of size controllable graphene micro/nanogap with a micro/nanowire mask method for organic fieldeffect transistors Appl. Phys. Lett. 99, 103301 (2011); 10.1063/1.3634065 Influence of gate dielectrics on the performance of single-layered organic transistors and bi-layered organic lightemitting transistors prepared by the neutral cluster beam deposition methodThe neutral cluster beam deposition (NCBD) method has been applied to the production and characterization of ambipolar, heterojunction-based organic light-emitting field-effect transistors (OLEFETs) with a top-contact, multi-digitated, long-channel geometry. Organic thin films of n-type N,N 0 -ditridecylperylene-3,4,9,10-tetracarboxylic diimide and p-type copper phthalocyanine were successively deposited on the hydroxyl-free polymethyl-methacrylate (PMMA)-coated SiO 2 dielectrics using the NCBD method. Characterization of the morphological and structural properties of the organic active layers was performed using atomic force microscopy and X-ray diffraction. Various device parameters such as hole-and electron-carrier mobilities, threshold voltages, and electroluminescence (EL) were derived from the fits of the observed current-voltage and current-voltage-light emission characteristics of OLEFETs. The OLEFETs demonstrated good field-effect characteristics, well-balanced ambipolarity, and substantial EL under ambient conditions. The device performance, which is strongly correlated with the surface morphology and the structural properties of the organic active layers, is discussed along with the operating conduction mechanism. V C 2014 AIP Publishing LLC. [http://dx.

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In this paper, we report on the fabrication and electrical characterization of top-contact, ambipolar organic field-effect transistors (OFETs) and inverters based upon a heterostructure of p-type pentacene on n-type N,N′-ditridecylperylene-3,4,9,10-tetracarboxylic di-imide (P13), using the neutral cluster beam deposition (NCBD) method. The device characteristics measured as a function of both P13 and pentacene layer thicknesses revealed that OFETs with thicknesses of P13 (300 Å) and pentacene (200 Å) showed high air-stability and well-balanced ambipolarity with hole and electron mobilities of 0.12 and 0.08 cm2/V s. The complementary inverters, comprising two identical ambipolar OFETs, were found to operate both in the first and third quadrants of the transfer curves and exhibited a high voltage inversion gain of 13, good noise margins, and little hysteresis under ambient conditions. The results presented demonstrate that the NCBD-based ambipolar transistors and inverters qualify them as promising potential candidates for the construction of high-performance, organic thin film-based integrated circuits.