bluuebunny/crossref_metadata_2025 huggingface dataset:
SiC Nanowire Film Photodetectors: A Promising Candidate Toward High Temperature Photodetectors
Authors: Chong Haining , Yang Huijun , Yang Weiyou , Zheng Jinju , Shang Minghui , Yang Zuobao , Wei Guodong , Gao Fengmei
Published: April 2016

In this study, UV photodetectors (PDs) based on SiC nanowire films have been successfully prepared by a simple and low-cost drip-coating method followed by sintering at 500 °C. The corresponding electrical characterizations clearly demonstrate that the SiC nanowire based PD devices
can be regarded as a promising candidate for UV PDs. The PDs can exhibit the excellent performances of fast, high sensitivity, linearity, and stable response, which can thus achieve on-line monitoring of weak UV light. Furthermore, the SiC nanowire-based PDs enable us to fabricate detectors
working under high temperature as high as 150 °C. The high photosensitivity and rapid photoresponse for the PDs can be attributed to the superior single crystalline quality of SiC nanowires and the ohmic contact between the electrodes and nanowires.
Study of Ac Dielectrophoretic Process of SiC Nanowires: A Universal Method for Alignment of Semiconductor Nanowires
Authors: Yao Limei , Cui Yan , Cong Haining , Zheng Jinju , Shang Minghui , Yang Zuobao , Yang Weiyou , Wei Guodong , Gao Fengmei
Published: April 2016

In this study, the dielectrophoretic processes of SiC nanowires suspended in three typical solvents, (highly purified water, ethanol and isopropanol) were systematically investigated. Optical microscope and SEM characterizations were used to observe the order of SiC nanowires on the
surface of gold microchannels. The gold microchannels were induced by Ac dielectrophoresis of the corresponding dispersion solutions of SiC nanowires, with a concentration of 0.1 mg/mL. The study shows that the dielectrophoresis process is an effective way of synthesizing highly oriented SiC
nanoarrays using isopropanol solution. The results also show that the arrangement of SiC nanowires on the interdigital electrode configuration not only depend on the kind of solvent used, but also on the applied frequency (1000 Hz∼1 MHz) and voltage (1 V∼20 V).
Near Infrared Quantum Cutting of Tb3+–Yb3+ Co-Doped CeF3 Nanophosphors
Authors: Xiao Sun , Xiao-Yun Hu , Wen-Qian Hou , Jun Fan , Hui Miao , Su-Chang Zhan
Published: April 2016

In this paper, Tb3+–Yb3+ Co-doped CeF3 nanophosphors were synthesized using the microwave-assisted heating hydrothermal method (M–H). The excitation and emission spectra of the samples at room temperature show that the samples absorb ultraviolet
light from 250 nm to 280 nm, and emit light at 300 nm. This corresponds to the transitions from 5D to 4F of Ce3+, 480 nm, 540 nm, 583 nm, 620 nm which correspond to the transitions from 5D4 to 7F6,5,4,3 of Tb3+,
973 nm which corresponds to the transitions from 2F5/2–2F7/2 of Yb3+. In the emission spectra, it is clear that the emission intensity of Ce3+ and Tb3+ decreases, and Yb3+ increases with increasing
Yb3+. This suggests that energy transfer from Ce3+ to Yb3+, and Ce3+ to Tb3+ to Yb3+ may occur. In the near infrared emission area, it is noted that a distinct emission centered at 973 nm was observed under 260 nm excitation.
This is due to transitions among the different Stark levels of 2FJ(J=5/2, 7/2) Yb3+ ions. This also suggests an energy transfer from Ce3+ ions to Tb3+ and then to Yb3+. The energy transfers from Tb3+–Yb3+
Co-doped CeF3 nanophosphors, which lead to intense NIR emissions at 900–1050 nm, match the energy of Si band gaps of Si-based solar cells. Therefore, these kinds of materials are promising candidates for applications that require modifying if solar spectrums and enhancement
of conversion efficiency of Si-based solar cells.
Improving the Fluorescence Concentration Quenching of Porphyrin Potassium Salt by Ag Nano Colloids
Authors: Yang Ailing , Wang Ning , Wang Yujin , Li Shunpin , Wang Lele , Yang Yun , Bao Xichang , Yang Renqiang
Published: April 2016

Silver nanoparticles (NPs) with diameters less than 25 nm, and 5, 10, 15, 20-tetrakis(4-carboxy-phenyl) porphyrin potassium salt (K4TCPPS) was synthesized. By adding silver colloids into the K4TCPPS solutions, the fluorescence concentration quenching of the K4TCPPS
solutions was improved between 1×10−6–5×10−4 M, depending on the size of the Ag NPs, the concentration of the K4TCPPS and the excitation wavelength. Under excitation wavelengths of 360 and 414 nm, the enhancement was in the range
of 0.34–22.8, and 0.71–82.46, respectively. The enhancement increased with decreasing size of the Ag NPs. At the two highest enhancements, the concentrations of the K4TCPPS solutions were 1×10−4 and 1×10−5 M respectively,
and the size of the Ag NPs was about 5 nm. The main reasons for the fluorescence enhancing effect are due to fluorescence resonance energy transfer (FRET) between K4TCPPS molecules and Ag NPs, and decreased collision quenching between free K4TCPPS molecules, and free K4TCPPS
molecules with Ag NPs. Our results showed that Ag NPs with sizes of about 5 nm can effectively improve the fluorescence concentration quenching of K4TCPPS solutions. This result also suggests that it is possible to use noble metal NPs to improve fluorescence concentration quenching.
Synthesis of Au-SiO2 Composite Nanospheres and Their Catalytic Activity
Authors: Dexuan Wang , Guian Li , Qingyan Han , Ziqiang Wang , Liping Pan , Zhongyue Zhang , Hairong Zheng
Published: April 2016

We report a simple and environmentally friendly approach to the synthesis of Au-SiO2 composite nanospheres. Our method presents a route for the decoration of preformed amine functionalized SiO2 nanospheres by in situ formation of Au nanoparticles at three
different concentrations of Au precursor (HAuCl4). Herein, the silane coupling agent (KH-550) is used as an intermediary to connect the Au nanoparticles to the surfaces of the SiO2 nanospheres, which helps avoid the aggregation of Au nanoparticles. The crystal structure,
chemical elements, morphology and catalytic properties of the Au-SiO2 composite nanospheres were analyzed by transmission electron microscopy (TEM), X-Ray powder diffraction (XRD), UV-vis-spectrophotometer (UV-vis) and X-ray photoelectron spectroscopy (XPS). The analytical results
demonstrate that the Au nanoparticles (4–9 nm) were homogeneously distributed on the surface of the SiO2 nanospheres, which had a good FCC crystal structure. Moreover, the Au-SiO2 composite nanospheres exhibited good catalytic properties, measured by their ability
to reduce organic dyes. The Au-SiO2 composite nanospheres are promising candidates for applications in catalysis and wastewater treatment.
Hydrothermal Synthesis and Luminescence Property of Nanoscaled BiPO4:Eu3+ Powders
Authors: Shi Xiaolei , Liu Yun , Zhang Jin , Zhang Kun , Li Peng , Zuo Haoqiang
Published: April 2016

Aseries of Bi1−xPO4:xEu3+ phosphors were prepared using a simple hydrothermal method. The effects of pH and Eu3+ doping on the structure, morphology and luminescence properties of BiPO4:Eu3+ were investigated systematically.
X-ray diffraction (XRD) and field emission scanning electron microscope (FE-SEM) results reveal that the as-prepared BiPO4 crystals are in a low temperature monoclinic phase (LTMP), and have a rod-like structure with a size in the range of 1–5 μm at pH 1. Increasing
the pH to 2 transforms the BiPO4 to its hexagonal phase (HP), with peanut-like structures ranging from 50 to 150 nm. At pH 1, when the doping level is increased to 0.07, the phase transformation from LTMP to HP occurs, meaning that the amount of HP components increase with increasing
Eu3+ doping. Furthermore, all the diffraction peaks of the Bi1−xPO4:xEu3+ can be fitted very well to HP when x = 0.11. The photoluminescence (PL) spectra suggest that orangered luminescence can be observed in the series of BiPO4:Eu3+
phosphors, and that concentration quenching occurs when x = 0.07.
“Secondary Growth” in Hydrothermal Synthesis of Aligned ZnO Nanostructures and Its Application in Dye-Sensitized Solar Cells
Authors: Liu Wenjun , Huang Qiaoling , Huang Tengji , Cao Peijiang , Han Shun , Jia Fang , Zhu Deliang , Ma Xiaocui , Lu Youming
Published: April 2016

One-dimensional (1D) aligned ZnO nanostructures were prepared on ZnO film seeded substrates using a low-temperature hydrothermal method, and zinc nitrate and hexamethylenetetramine (HMT) precursors. It was observed that increasing the concentration ratio of Zn2+/HMT from
1 to 100 led to a “secondary growth,” and a change in the morphologies of the ZnO nanostructures from arrays of thick nanorods to arrays of thin nanorod-step-thick nanorods. The morphological evolution of ZnO nanostructures with increased growth time at high Zn2+/HMT
concentration ratios showed the same transformation. Dye-sensitized solar cells (DSSCs) were fabricated using ZnO nanostructures as the photoanodes, and the electron transport properties were determined by electrochemical impedance spectroscopy (EIS). Although the DSSCs showed low power conversion
efficiencies due to the short lengths, the arrays of the thin nanorods demonstrated excellent electron transport with an electron diffusion coefficient (Dn) of 1.57×10−3 cm2/s, and an effective diffusion length (Ln) of 140 μm.
Temperature and Oxygen Sensing Properties of Ru(II) Covalently-Grafted Sol–Gel Derived Ormosil Hybrid Materials
Authors: Zhang Haoran , Lei Bingfu , Dong Hanwu , Liu Yingliang , Zheng Mingtao , Xiao Yong
Published: April 2016

In this article, oxygen and temperature-sensing hybrid materials consisting of [Ru(Phen)3]2+ portions covalently-grafted onto the sol–gel derived ormosil network were prepared by co-condensation of tetraethoxysilane (TEOS) using n-octyltriethoxysilane
as the network modifier. For comparison purposes, the hybrid materials in which [Ru(Phen)3]2+ were conventionally physically-incorporated into the matrix were also prepared. The obtained hybrid materials were characterized by Fourier transform infrared (FT-IR), luminescence
intensity oxygen quenching Stern-Volmer plots, temperature quenching plots and excited-state lifetime. The near linear Stern-Volmer plots can be attributed to the approximate heterogeneous environment of the luminophore within the ormosil materials. The results reveal that the covalently-grafted
sample is more sensitive to O2, and has a higher sensing sensitivity and a higher thermal activation energy compared to the physically-incorporated one, since these Ru(II) molecules are strongly covalently-grafted onto the Si–O network via the CH2–Si bonds
and less –OH group.
Performance Enhancement of Small Molecular Solar Cells by Bilayer Cathode Buffer
Authors: Sun Qinjun , Zhao Huanbin , Zhou Miao , Gao Liyan , Hao Yuying
Published: April 2016

An effective composite bilayer cathode buffer structure is proposed for use in small molecular solar cells. CsF was doped in Alq3 to form the first cathode buffer, leading to small serial resistances. BCP was used as the second cathode buffer to block the holes to the electrode. The
optimized bilayer cathode buffer significantly increased the short circuit and fill factor of devices. By integrating this bilayer cathode buffer, the CuPc/C60 small molecular heterojunction cell exhibited a power conversion efficiency of up to 0.8%, which was an improvement of
56% compared to a device with only the Alq3 cathode buffer. Meanwhile, the bilayer cathode buffer still has a good protective effect on the performance of the device.
Mechanism of Biological Compatibility of Water-Soluble Yb3+, Er3+ Codoped NaYF4 Nanoparticles
Authors: Liu Chen , Chen Huan , Li Shouying , Xu Hong , Zhao Dan
Published: April 2016

Water soluble NaYF4 nanocrystals codoped with 20 mol% Yb3+, 2 mol% Er3+ were prepared by a facile solvothermal approach using polyvinylpyrrolidone (PVP) as a surfactant. As a potential material for luminescent probes, in votroeffects of upconversion
nanoparticles (UCNPs) on human aenocarcinoma (SGC-7901) cells with different concentrations were observed. These effects range from cell viability, mitochondrial membrane potential (MMP), reactive oxygen species (ROS) production, AnnexinV-FITC–propidiumiodide (PI) apoptosis detection,
and cell cycles. Our results demonstrated that the cells treated with UCNPs showed a decrease in cell viability accompanied the decreased MMP and the release of ROS. When treated with 400 μg/mL UCNPs, AnnexinV-FITC–PI apoptosis detection showed the UCNPs induced apoptosis,
the cell cycle indicated the UCNPs suppressor cells in the G1 phase obviously, thereby reducing cell activity.
Correlated Color Temperature Tunable White Electroluminescence from Cadmium-Free ZnS Quantum Dots
Authors: Zhang Xiaosong , Li Lan , Ji Ting , Xuan RongWei , Xu JianPing , Liu Xiaojuan
Published: April 2016

We propose correlated color temperature tunable white light-emitting from different sizes cadmiumfree quantum dots (QDs) without organic ligand-modulation. A size series of free-standing ZnS QDs were prepared by coprecipitation method. Experimental results show that the broad electroluminescences
(EL) spectra from all samples cover almost the entire visible region and the electroluminescence peak is significantly redshifted from 489 to 580 nm with ZnS QDs sizes increasing from 1.1 to 4 nm. Moreover, the chromaticity coordinates calculated from EL spectra are (0.27, 0.36), (0.36, 0.42)
and (0.42, 0.46) for QDs with average sizes 1.1, 2 and 4 nm drived at 15 V respectively, correspondingly, white EL spectra with a continuously tunable color changes from bluish white (CCT 12400 K) to yellowish white (CCT 3700 K). The differences between the photoluminescence (PL) and EL spectra
were observed. Furthermore, the comparison between EL and PL spectra and active defect-levels of ZnS QDs with various sizes are discussed to understand the mechanism of the tunable spectra. The results offer that a convenience method to obtain tunable EL spectra in white color from ZnS QDs
defects by controlling the size of the QDs.
The Experiment and Simulation Method to Calibrate the Shear Modulus of Individual ZnO Nanorod
Authors: Yu Guangbin , Jiang Chengming , Dai Bing , Song Jinhui
Published: April 2016

A general method is presented to directly measure the shear modulus of an individual nanorod using atomic force microscope (AFM). To obtain shear modulus with less experiment error, finite element simulation is employed to simulate the twisting process of a ZnO nanorod. Based on the
experimental measurements, the shear modulus of ZnO nanorod with 4 μm in length and 166 nm in radius is characterized to be 9.1±0.2 GPa, which is obviously more accurate than the simple averaged experimental result.
Modification of Multilayer Carbon Nanotubes for the Removal of Arsenate
Authors: Liao Libing , Liu Gin-Lung , Jean Jiin-Shuh , Jiang Wei-Teh , Li Zhaohui
Published: April 2016

The aim of this study was to explore a new nano-composite carbon adsorbent material for the removal of arsenic from water. The multilayer carbon nanotubes (MCNTs) were treated with different acids and/or modified with iron to create more surface COOH sites or Fe-impregnated MCNTs for
the enhanced uptake of As(V). Tests were conducted as a function of initial As(V) concentrations, contact time, and solution pH. The coverage of ferric hydroxides on MCNTs and the uptake of As on Fe-MCNTs were independently confirmed by field emission scanning electron microscope and energy
dispersive X-ray spectroscopy analyses. With an As(V) uptake capacities of 27 mg/g on Fe-MCNTs and 14 mg/g on acid-MCNTs, the material showed superior performance for As(V) removal.
Charge Effect on the Quantum Dots-Peptide Self-Assembly Using Fluorescence Coupled Capillary Electrophoresis
Authors: Wang Jianhao , Li Jingyan , Teng Yiwan , Bi Yanhua , Hu Wei , Li Jinchen , Wang Cheli , Qiu Lin , Jiang Pengju
Published: April 2016

We present a molecular characterization of metal-affinity driven self-assembly between CdSe–ZnS quantum dots and a series of hexahistidine peptides with different charges. In particular, we utilized fluorescence coupled capillary electrophoresis to test the self-assembly process
of quantum dots with peptides in solution. Four peptides with different charges can be efficiently separated by fluorescence coupled capillary electrophoresis. The migration time appeared to be influenced by the charges of the peptide. In addition, the kinetics of self-assembly process of
quantum dots with one of the peptides manifested a bi-phasic kinetics followed by a saturating stage. This work revealed that there exist two types of binding sites on the surface of quantum dots for peptide 1: one type termed “high priority” binding site and a “low priority”
site which is occupied after the first binding sites are fully occupied. The total self-assembly process finishes in solution within 80 s. Our work represents the systematic investigation of the details of self-assembly kinetics utilizing high-resolution fluorescence coupled capillary electrophoresis.
The charge effect of peptide coating quantum dots provides a new way of preparing bioprobes.
Development of Biogenic Silver Nanoparticle Using Rosa Chinensis Flower Extract and Its Antibacterial Property
Authors: Meng Yongde , Sun Yanjie
Published: April 2016

In the present study, biosynthesis of silver nanoparticles was carried out using Rosa chinensis flower extract as reducing agent. The characterization of silver nanoparticles was done by UV-VIS spectrum. The morphology and size of silver nanoparticles were determined by transmission
electron microscope (TEM) image. The crystallization of silver nanoparticles was confirmed by X-ray diffraction (XRD) measurements. The Fourier transform infrared (FT-IR) analysis was used to confirm the possible involvement in the formation and stabilization of synthesized silver nanoparticles
by the extract of Rosa chinensis flower. Antibacterial activity of silver nanoparticles was studied against Gram positive Staphycoccus aureus and Gram negative Escherichia coli.
Raising the Thermoelectric Performance of Fe3CoSb12 Skutterudites via Nd Filling and In-Situ Nanostructuring
Authors: Guo Lijie , Cai Zhengwei , Xu Xiaolong , Peng Kunling , Wang Guiwen , Wang Guoyu , Zhou Xiaoyuan
Published: April 2016

p-type skutterudites NdxFe3CoSb12 with x equaling 0.8, 0.85, 0.9, 0.95, 1.0 have been synthesized by solid state reaction followed by spark plasma sintering. The influence of Nd filling on electrical and thermal transport properties has
been investigated in the Nd-filled skutterudite compounds in the temperature range from room temperature to 800 K. It was found that the Seebeck coefficient is drastically enhanced via filling Nd in p-Type skutterudites as well as the corresponding power factor although electrical conductivity
is reduced. In addition, a large reduction in thermal conductivity is achieved by Nd fillers through rattling effect along with the In-Situ nanostructured precipitate through scattering phonons with much wider frequency. These concomitant effects result in an enhanced thermoelectric
performance with the dimensionless figure of merit ZT. These observations demonstrate an exciting scientific opportunity to raise the figure-of-merit of p-type skutterudites.
Influence of Parametric Variations on Hydrothermal Growth of ZnO Nanostructures for Hybrid Polymer/ZnO Based Photodetector
Authors: Dixit Tejendra , Bilgaiyan Anubha , Palani I. A , Singh Vipul
Published: April 2016

Dumbbell and flower like ZnO nano-crystals were grown via hydrothermal process. The as-prepared dumbbells, with length of 0.8–10 μm and edge length of 0.3–0.8 μm possess a hexagonal structure, while flowers with lengths ranging from 1–6 μm with hexagonal structure
have been synthesized. The effect of temperature, solution concentration and growth time on the size and shapes of the ZnO nanostructures has been studied using Field emission scanning electron microscope (FESEM) and X-ray diffractometer (XRD). Further the optical properties of nanostructures
were investigated by Photoluminescence (PL) spectroscopy, which shows emission in UV and visible regions. From Diffused reflectance spectroscopic analysis (DRA) it was observed that ZnO nanodumbbells and nanoflowers have a direct band gap of 3.27 eV and 3.25 eV respectively. The I–V
plot showed dependence of current values under dark and illumination over the annealing temperature during the growth stage. Thus we report a control over the shape and dimension of nanostructures by varying various parameters having implications for (opto)electronic devices.
Emission Behavior of Crystalline 1,4-Bis(4-phenylthiophene-2-yl)benzene Film Under Optical Excitation with Ultra Short Pulses
Authors: Mochizuki Hiroyuki , Kawaguchi Yoshizo , Sasaki Fumio , Hotta Shu
Published: April 2016

We evaluated emission behaviors of crystallized films of 1,4-bis(5-phenylthiophene-2-yl)benzene (AC5) in detail which was a representative thiophene/phenylene co-oligomer. The crystallized AC5 films were prepared by vapor deposition onto a substrate and thermal treatment. The AC5 films
consisted of a crystalline domain with the size of several tens of micrometers. We used femtosecond laser pulses for the excitation of the AC5 films. As a result, the femtosecond laser pulses did not induce re-absorption above excitation energy densities of their laser threshold. The obtained
gain value for AC5 crystallized film was large, over 150 cm-1. Furthermore, the emission cross section of the crystallized AC5 film was nearly 10-16 cm2.
Spectrally-Narrowed Emissions from Organic Crystals Having a One-Dimensional Grating on Their Surface
Authors: Yamamoto Hiroyuki , Obara Keiji , Higashihara Shohei , Obama Yuki , Yamao Takeshi , Hotta Shu
Published: April 2016

We have succeeded in directly engraving one-dimensional diffraction gratings on the surface of organic semiconducting oligomer crystals by using focused ion beam (FIB) lithography and laser ablation (LA) methods. The FIB method enabled us to shape the gratings with varying periods down
to ∼150 nm. With the LA method a large-area grating with a ∼500-nm period was readily accessible. All the above crystals indicated spectrally-narrowed emission (SNE) lines even in the case of shallow groove depths ∼2–4 nm. In particular, we definitively observed the SNE pertinent
to the first-order diffraction with the crystal having the diffraction grating of a 148.3-nm average period. The present results indicate utility of the built-in gratings that can directly be fabricated on the surface of the crystals.
Evaluation of Thermal Stability of Organic Electro-Optic Device by Using Thermally Stimulated Current
Authors: Ikemoto Ryoma , Taguchi Dai , Manaka Takaaki , Iwamoto Mitsumasa , Yamada Toshiki , Otomo Akira
Published: April 2016

Thermally stimulated current (TSC) measurement was employed to study the thermal stability of electro-optic (EO) polymers, i.e., guest/host polymer DR1/PMMA and side-chain polymer PMMA-co-DR1. Here the isothermal relaxation test showed that the relaxation time τ (85 °C)
of side-chain polymer PMMA-co-DR1 is longer than that of guest/host polymer DR1/PMMA. TSC peaks appeared symmetrically in proportion to the poling electric field Ep, indicating that DR1 molecules make a dominant contribution to dipolar depolarization. Thermal sampling
(TS) method showed that the activation energy of the DR1/PMMA is around 1 eV, while that of the PMMA-co-DR1 is distributed > 1 eV. Results suggested that side-chain polymer is preferable to the guest/host polymer in the thermal stability. TSC measurement is helpful as a conventional
method for studying the life time of EO polymers in terms of dipolar motion.
Physical Property Evaluation of ZnO Thin Film Fabricated by Low-Temperature Process for Flexible Transparent TFT
Authors: Khafe Adie Bin Mohd , Watanabe Hiraku , Yamauchi Hiroshi , Kuniyoshi Shigekazu , Iizuka Masaaki , Sakai Masatoshi , Kudo Kazuhiro
Published: April 2016

The usual silicon-based display back planes require fairly high process temperature and thus the development of a low temperature process is needed on flexible plastic substrates. A new type of flexible organic light emitting transistor (OLET) had been proposed and investigated in the
previous work. By using ultraviolet/ozone (UV/O3) assisted thermal treatments on wet processed zinc oxide field effect transistor (ZnO-FET), through low-process temperature, ZnO-FETs were fabricated which succeeded to achieve target drain current value and mobility. In this study,
physical property evaluation of ZnO was conducted in term of their crystallinity, the increase composition of ZnO formed inside the thin film and the decrease of the carbon impurities originated from aqueous solution of the ZnO itself. The X-ray diffraction (XRD) evaluation showed UV/O3
assisted thermal treatment has no obvious effect towards crystallinity of ZnO in the range of low process temperature. Moreover, through X-ray photoelectron spectroscopy (XPS) evaluation and Fourier transform infrared (FT-IR) spectroscopy evaluation, more carbon impurities disappeared from
the ZnO thin film and the increase of composition amount of ZnO, when the thin film was subjected to UV/O3 assisted thermal treatment. Therefore, UV/O3 assisted thermal treatment contributed in carbon impurities elimination and accelerate ZnO formation in ZnO thin film,
which led to the improvement in the electrical property of ZnO-FET in the low-process temperature.
N-Type Conductive Polymer Having a Concept of Self-Dope: —Poly(P-methylpyridinium vinylene)—
Authors: Onoda Mitsuyoshi
Published: April 2016

Novel self-doped N-type conducting polymer, poly(P-methylpyridinium vinylene), PMePyV were synthesized by using the quaternization of poly(P-pyridyl vinylene), PPyV and several regiochemical consequences in this polymer were proposed. The electrical, optical, and
electrochemical properties of self-doped N-type conductive polymer were observed. In addition, a possibility of a variety of functional applications of self-doped N-type conductive polymer was indicated.
Amplified Emission and Field-Effect Transistor Characteristics of One-Dimensionally Structured 2,5-Bis(4-biphenylyl)thiophene Crystals
Authors: Hashimoto Kazumasa , Sasaki Fumio , Hotta Shu , Yanagi Hisao
Published: April 2016

One-dimensional (1D) structures of 2,5-bis(4-biphenylyl)thiophene (BP1T) crystals are fabricated for light amplification and field-effect transistor (FET) measurements. A strip-shaped 1D structure (10 m width) made by photolitography of a vapor-deposited polycrystalline film shows amplified
spontaneous emission and lasing oscillations under optical pumping. An FET fabricated with this 1D structure exhibits hole-conduction with a mobility of h = 8.0×10−3 cm2/Vs. Another 1D-structured FET is fabricated with epitaxially grown needle-like
crystals of BP1T. This needle-crystal FET exhibits higher mobility of h 034 cm2/Vs. This improved hole mobility is attributed to the single-crystal channel of epitaxial needles while the grain boudaries in the polycrystalline 1D-structure decrease the carrier transport.
Fabrication and Measurement of Electroluminescence and Electrical Properties of Organic Light-Emitting Diodes Containing Mott Insulator Nanocrystals
Authors: Nozoe Soichiro , Kinoshita Nobuaki , Matsuda Masaki
Published: April 2016

By using the short-time electrocrystallization technique, phthalocyanine (Pc)-based Mott insulator Co(Pc)(CN)2·2CHCl3 nanocrystals were fabricated and applied to organic light-emiting diodes (OLEDs). The fabricated device having the configuration ITO/Co(Pc)(CN)2·2CHCl3/Alq3/Al,
in which ITO is indium-tin oxide and Alq3 is tris(8-hydroxyquinolinato)aluminum, showed clear emission from Alq3, suggesting the Mott insulator Co(Pc)(CN)2·2CHCl3 can work as useful hole-injection and transport material in OLEDs.
Effects of Bimolecular Recombination on Impedance Spectra in Organic Semiconductors: Analytical Approach
Authors: Takata Masashi , Takagi Kenichiro , Nagase Takashi , Kobayashi Takashi , Naito Hiroyoshi
Published: April 2016

An analytical expression for impedance spectra in the case of double injection (both electrons and holes are injected into an organic semiconductor thin film) has been derived from the basic transport equations (the current density equation, the continuity equation and the Possion’s
equation). Capacitance-frequency characteristics calculated from the analytical expression have been examined at different recombination constants and different values of mobility balance defined by a ratio of electron mobility to hole mobility. Negative capacitance appears when the recombination
constant is lower than the Langevin recombination constant and when the value of the mobility balance approaches unity. These results are consistent with the numerical results obtained by a device simulator (Atlas, Silvaco).
Influence of Pentacene Interface Layer in ITO/-NPD/Alq3/Al Organic Light Emitting Diodes by Time-Resolved Electric-Field-Induced Optical Second-Harmonic Generation Measurement
Authors: Oda Yoshiaki , Sadakata Atsuo , Taguchi Dai , Manaka Takaaki , Iwamoto Mitsumasa
Published: April 2016

By using I–V, EL–V, displacement current measurement (DCM) and time-resolved electric-field-induced optical second-harmonic generation (TR-EFISHG) measurement, we studied the influence of interface pentacene layer inserted between ITO and -NPD layers in ITO/-NPD/Alq3/Al
OLEDs. All experiments were carried out for the OLEDs with and without a pentacene interface layer. The I–V and EL–V measurements showed the decrease of operating voltage of EL, the DCM showed the lowering of inception voltage of carrier injection by inserting
a pentacene interface layer. The TR-EFISHG measurement showed the faster accumulation of holes at the interface between the -NPD and Alq3 layers, which resulted in the relaxation of electric field of -NPD layer accomplished by the increase of the conductivity and the increase of
the electric field in the Alq3 layer. We conclude that TR-EFISHG measurement is helpful for understanding I–V and EL–V characteristics, and can be combined with other methods to give significant information which are impacted by the interface layer.
High-Mobility 6,13-Bis(triisopropylsilylethynyl) Pentacene Transistors Using Solution-Processed Polysilsesquioxane Gate Dielectric Layers
Authors: Matsuda Yu , Nakahara Yoshio , Michiura Daisuke , Uno Kazuyuki , Tanaka Ichiro
Published: April 2016

Polysilsesquioxane (PSQ) is a low-temperature curable polymer that is compatible with low-cost plastic substrates. We cured PSQ gate dielectric layers by irradiation with ultraviolet light at ~60 °C, and used them for 6,13-bis(triisopropylsilylethynyl) pentacene (TIPS-pentacene)
thin film transistors (TFTs). The fabricated TFTs have shown the maximum and average hole mobility of 1.3 and 0.78±0.3 cm2V−1s−1, which are comparable to those of the previously reported transistors using singlecrystalline TIPS-pentacene
micro-ribbons for their active layers and thermally oxidized SiO2 for their gate dielectric layers. It is therefore demonstrated that PSQ is a promising polymer gate dielectric material for low-cost organic TFTs.
Catalytic Improvement on Counter Electrode of Dye-Sensitized Solar Cells Using Electrospun Pt Nano-Fibers
Authors: Seo Hyunwoong , Shiratani Masaharu , Seneekatima Kannanut , Pornprasertsuk Rojana
Published: April 2016

A dye-sensitized solar cell is one of cost-competitive photovoltaic devices. For higher performance, all components have been actively studied and improved. However, Pt is still a dominant catalyst since first development although some catalytic materials were studied so far. Catalytic
materials of counter electrode play an important role in the performance because it supplies electrons from counter electrode to electrolyte. Therefore, the catalytic activation of counter electrode is closely connected with the performance enhancement. In this work, Pt nano-fiber was fabricated
by electrospinning and applied for the counter electrode. Its wide surface area is advantageous for good conductivity and catalytic activation. Morphological characteristics of nano-fibers were analyzed according to electrospinning conditions. Photovoltaic properties, cyclic voltammetry, impedance
analysis verified the catalytic activation. Consequently, dye-sensitized solar cell with Pt nano-fiber electrospun at 5.0 kV of applied voltage had higher performance than conventional dye-sensitized solar cell with Pt thin film. This work is significant for related researches because all
nano-fibers counter electrode material proposed so far never exceeded the performance of conventional Pt counter electrode.
Temperature Dependence of Field-Effect Mobility in Organic Thin-Film Transistors: Similarity to Inorganic Transistors
Authors: Okada Jun , Nagase Takashi , Kobayashi Takashi , Naito Hiroyoshi
Published: April 2016

Carrier transport in solution-processed organic thin-film transistors (OTFTs) based on dioctylben-zothienobenzothiophene (C8-BTBT) has been investigated in a wide temperature range from 296 to 10 K. The field-effect mobility shows thermally activated behavior whose activation
energy becomes smaller with decreasing temperature. The temperature dependence of field-effect mobility found in C8-BTBT is similar to that of others materials: organic semiconducting polymers, amorphous oxide semiconductors and hydrogenated amorphous silicon. These results indicate
that hopping transport between isoenergetic localized states becomes dominated in a low temperature regime in these materials.
Influence of Temperature Variation on Field Effect Transistor Properties Using a Solution-Processed Liquid Crystalline Semiconductor, 8TNAT8
Authors: Monobe Hirosato , Kimoto Masaomi , Shimizu Yo
Published: April 2016

In this study, we used a liquid crystalline (LC) semiconductor, 8TNAT8, solution (e.g., 0.1 wt% in toluene) for forming an organic semiconductor layer by solution casting method, and fabricated bottom-gate/bottom-contact type field effect transistors (FETs). These LC semiconductors
show FET characteristic properties and have high carrier mobility of 0.01 cm2 V−1 s−1. We have investigated the surface morphology and the influence of temperature variation on LC FET properties across the phase transition from crystal to mesophase
of a LC semiconductor, 8TNAT8. In the most cases, FET mobility was irreversibly decreased after temperature heat stress above the melting point of 8TNAT8, owing to the morphological change of LC layer.
Organic Position-Sensitive Detectors Based on ZnO:Al and CuPc:C60
Authors: Morimune Taichiro , Kajii Hirotake , Nishimaru Hiroki , Ono Shinji
Published: April 2016

Organic position-sensitive detector (OPSD) based on copper phthalocyanine CuPc:fullerene C60 bulk-heterojunction with an inverted structure have been fabricated using aluminum doped ZnO (ZnO:Al) as a resistive layer, which is prepared by sol–gel method. The resistance
length of the one-dimensional PSD is fixed at 5 mm, and the Ag common electrode is fabricated by vacuum evaporation within the 100-μm width. The current density–voltage characteristics with different structures of photodetector, the influence of ZnO:Al resistivity on the thickness
and the position characteristics of PSDs are investigated. The experimental results indicate that the architecture, which uses an inverted structure, increases sensitivity under red light illumination compared to the conventional structure. In addition, the thickness of the ZnO:Al has influence
on the position characteristics. The resistivity of ZnO:Al film with Al doping concentration of 2 mol% prepared in this study is around 150 Ωcm and it increases from less than approximately 400 nm-thickness. These characteristics seem to be correlated with the properties of ZnO:Al
resistive layer. For a device with a 620 nm-thick ZnO:Al layer, the measured position values obtained from the output photocurrent agree with the actual position values under red laser light illumination. CuPc:C60 OPSD with an inverted structure exhibits red light sensitivity, high
incident-photon-to-current conversion efficiency of above 80% at −3 V and linearity error of 5.9% at −2V.
Transport Characteristics of the Organic Field-Effect Transistors Based on Charge Transfer Complex as Semiconductors
Authors: Yokokura Seiya , Takahashi Yukihiro , Hasegawa Hiroyuki , Harada Jun , Inabe Tamotsu , Matsushita Michio M , Awaga Kunio
Published: April 2016

The n-type organic field-effect transistors are fabricated with using four kinds of charge transfer (CT) complexes with PXX (peri-xanthenoxanthene) as a donor component. The CT complexes with four kinds of acceptors form mixed-stack type one-dimentional columns with different
PXX-acceptor overlaps. Comparison of the field-effect properties reveals the correlation between the device performance and intermolecular interaction in the semiconducting CT complexes.
Opportunities for Low Cost Processing of Erbium 8-Quinolinolates for Active Integrated Photonic Applications
Authors: Penna Stefano , Mattiello Leonardo , Bartolo Silvia Di , Pizzoleo Angelo , Attanasio Vincenzo , Beleffi Giorgio Maria Tosi , Otomo Akira
Published: April 2016

Erbium-doped organic emitters are promising active materials for Photonic Integrated Circuits (PICs) due to their emission shown at 1550 nm combined to the potential low cost processing. In particular, Erbium Quinoline (ErQ) gained a strong interest in the last decade for the good emission
efficiency. This contribution reports the results derived from the application of ErQ as active core material within a buried optical waveguide, following the development of a purposed optical process to control the refractive index of ErQ and then to define a patterned structure from a single
thin film deposition step. The reported results show the potential of Er-doped organic materials for low cost processing and application to planar PICs.
Organic Light-Emitting Diodes with Heterojunction of Thiophene/Phenylene Co-Oligomer Derivatives
Authors: Dokiya Shohei , Ono Yasuyuki , Sasaki Fumio , Hotta Shu , Yanagi Hisao
Published: April 2016

Organic light-emitting diodes are fabricated by heterojunction of thiophene/phenylene co-oligomer films using biphenyl-capped bithiophene (BP2T) and its cyano-substituted derivative (BP2T-CN). Strong electron-withdrawing cyano-groups in BP2T-CN transform the p-type BP2T into
n-type. Photoluminescence and electroluminescence from their bilayered films dominantly result from the BP2T-CN layer since the lying molecular orientation of BP2T-CN facilitates surface emission while the standing orientation of BP2T is not suitable for the device configuration. The
current density and electroluminescence intensity are considerably increased by carrier doping with MoO3 and Cs2CO3 into the BP2T and BP2T-CN films, respectively.
Design of Far-Red Sensitizing Squaraine Dyes Aiming Towards the Fine Tuning of Dye Molecular Structure
Authors: Morimoto Takuya , Fujikawa Naotaka , Ogomi Yuhei , Pandey Shyam S , Ma Tingli , Hayase Shuzi
Published: April 2016

Model squaraine dyes having sharp and narrow absorptions mainly in the far-red wavelength region has been logically designed, synthesized and used for their application as sensitizer in the dyesensitized solar cells (DSSC). In order to have fine control on energetics, dyes having same
mother core and alkyl chain length varying only in molecular symmetry and position of substituent were designed. It has been found that even keeping all other structural factor constant, only positional variation of substituent leads to not only in the variation of energetics by 0.1 eV but
affects the photovoltaic characteristics also. Optimum concentration of dye de-aggregating agent was found to be 100 times with respect to the sensitizing dye concentration. Amongst dyes utilized in this work best performance was obtained for unsymmetrical dye SQ-40 giving a photoconversion
efficiency of 4.01% under simulated solar irradiation at global AM 1.5.
Study of Electrical Conduction Mechanism of Organic Double-Layer Diode Using Electric Field Induced Optical Second Harmonic Generation Measurement
Authors: Nishi Shohei , Taguchi Dai , Manaka Takaaki , Iwamoto Mitsumasa
Published: April 2016

By using electric field induced optical second harmonic generation (EFISHG) and current voltage (I–V) measurements, we studied the electrical transport mechanism of organic doublelayer diodes with a structure of Au/N, N′-di-[(1-naphthyl)-N, N′-diphenyl]-(1,1′-biphenyl)-4,4′-diamine
(α-NPD)/poly(methyl methacrylate) (PMMA)/indium zinc oxide (IZO). Here the α-NPD is a carrier transport layer and the PMMA is an electrical insulating layer. The current level was very low, but the I–V characteristics showed a rectifying behavior.
The EFISHG measurement selectively and directly probed the electric field across the α-NPD layer, and showed that the electric field across the α-NPD layer is completely relaxed owing to the charge accumulation at the α-NPD/PMMA interface in the region
V>0, whereas the carrier accumulation was not significant in the region V<0. On the basis of these experimental results, we proposed a model of the rectification. Further, by coupling the I–V characteristics with the EFISHG measurement, the I–V
characteristics of the diodes were well converted into the current-electric field (I–E) characteristics of the α-NPD layer and the PMMA layer. The I–E characteristics suggested the Schottky-type conduction governs the carrier transport.
We conclude that the I–V measurement coupled with the EFISHG measurement is very useful to study carrier transport mechanism of the organic double-layer diodes.
Degradation of Bilayer Organic Light-Emitting Diodes Studied by Impedance Spectroscopy
Authors: Sato Shuri , Takata Masashi , Takada Makoto , Naito Hiroyoshi
Published: April 2016

The degradation of bilayer organic light-emitting diodes (OLEDs) with a device structure of N, N′-di(1-naphthyl)-N, N′-diphenylbenzidine (α-NPD) (hole transport layer) and tris-(8-hydroxyquinolate)aluminum (Alq3) (emissive layer
and electron transport layer) has been studied by impedance spectroscopy and device simulation. Two modulus peaks are found in the modulus spectra of the OLEDs below the electroluminescence threshold. After aging of the OLEDs, the intensity of electroluminescence is degraded and the modulus
peak due to the Alq3 layer is shifted to lower frequency, indicating that the resistance of the Alq3 layer is increased. Device simulation reveals that the increase in the resistance of the Alq3 layer is due to the decrease in the electron mobility in the Alq3
layer.
Self-Spreading of Lipid Bilayer on a Hydrophobic Surface Made by Self-Assembled Monolayer with Short Alkyl Chain
Authors: Omori Yuya , Sakaue Hiroyuki , Takahagi Takayuki , Suzuki Hitoshi
Published: April 2016

Behaviors of self-spreading of lipid bilayer membrane on a glass surface modified with selfassembled monolayer (SAM) with short alkyl chain were observed with fluorescence microscopy. Hydrophobic surface made by SAM was found to hamper the self-spreading phenomenon but the lipid bilayer
spread on a hydrophilic one where SAM was decomposed by oxidation. On a binary surface having a hydrophobic region and a hydrophilic one, the lipid bilayer spread on the hydrophilic region but it stopped at the boundary of the hydrophobic region.
Development of UV Light Irradiation Patterning of Bacteriorhodopsin Thin Films for Biomimetic Functional Devices
Authors: Haruyama Yoshihiro , Kasai Katsuyuki , Yamada Toshiki , Tanaka Shukichi , Tominari Yukihiro , Kaji Takahiro , Kitamura Masaya , Otomo Akira
Published: April 2016

We developed a new patterning method for bacteriorhodopsin (bR) thin films using UV light irradiation. The proton pump function of bR thin films can be deactivated with UV light irradiation. Inactivation of the proton pump function of bR is related to structural changes or photo-bleaching
of the retinal in bR using UV light exposure, which was confirmed with absorption and Raman spectroscopy measurements. Utilizing inactivation of the proton pump function with UV light irradiation, we prepared a bR photocell with a stripe-patterned bR thin film and measured its photocurrent
response. The new patterning method is applicable to complicated patterning and patterning with a higher spatial resolution, which extends the application of bR thin films as sensor devices.
Cytocompatibility of HeLa Cells to Nano-Sized Ceramics Particles
Authors: Seitoku Eri , Abe Shigeaki , Kusaka Teruo , Nakamura Mariko , Inoue Satoshi , Yoshida Yasuhiro , Sano Hidehiko
Published: April 2016

In this study, we investigated the behaviors and cytocompatibility response of human cervical carcinoma (HeLa) cells expose to nano-sized particles. Cultivated cells exposed to titanium oxide and indium oxide nanoparticles remained highly viable. In the presence of copper oxide (CuO);
however, the cells became seriously inflamed. To understand the mechanism by which CuO causes cell death, we evaluated cell death and apoptosis cytometry. CuO induced cells apoptosis more strongly than exposure to titania nanoparticles. Confocal fluorescence microscopy revealed that the nano-sized
particles penetrate the cells.
Chemical Vapor Deposition of MoS2: Insight Into the Growth Mechanism by Separated Gas Flow Experiments
Authors: Yanase Takashi , Watanabe Sho , Weng Mengting , Nagahama Taro , Shimada Toshihiro
Published: April 2016

We report detailed experiments on chemical vapor deposition of an atomic layer semiconductor MoS2. We developed a new type of CVD system in which MoO3 and S sources are separately supplied to the substrates. It has become possible to precisely control the supply
of the materials separately in the order of seconds. Raman and XPS analysis of the films grown under various conditions revealed that the initially obtained films are S-deficient and complete stoichiometry is reached after several minutes under S vapor flow.
Wettability Control of Gold Surfaces Modified with Benzenethiol Derivatives: Water Contact Angle and Thermal Stability
Authors: Tatara Shingo , Kuzumoto Yasutaka , Kitamura Masatoshi
Published: April 2016

The water wettability of Au surfaces has been controlled using various benzenethiol derivatives including 4-methylbenzenethiol, pentafluorobenzenethiol, 4-fluorobenzenethiol, 4-methoxybenzenethiol, 4-nitrobenzenethiol, and 4-hydroxybenzenethiol. The water contact angle of the Au surface
modified with the benzenethiol derivative was found to vary in the wide range of 30.9° to 88.3°. The contact angle of the modified Au films annealed was also measured in order to investigate their thermal stability. The change in the contact angle indicated that the modified surface
is stable at temperatures below about 400 K. Meanwhile, the activation energy of desorption from the modified surface was estimated from the change in the contact angle. The modified Au surface was also examined using X-ray photoelectron spectroscopy.