中村 一希

Thin films of mesoporous lamellar nickel oxides and nanotube manganese oxides were electrochemically fabricated on indium tin oxide (ITO) glass using sodium n-dodecyl sulfate (SDS) as a template agent under different controlled potentials in 10 mM Ni(NO 3) 2 and 100 mM MnSO 4 solutions. Electrochromic characterization together with the morphological observation by transmission electron microscopy (TEM), structure analysis by X-ray diffraction (XRD) and electron diffraction (ED) was made. Nickel and manganese oxide films of nanostructures, compared with conventional structure ones, showed marked changes in optical transmittance and electric charge with regard to the electrochromic reactions in aqueous solution of 100 mM LiOH. However, in a non-aqueous γ-butyrolactone (GBL) solution of 100 mM Bis(trifluoromethane)sulfonimide lithium, the nickel oxide films did not show any notable electrochromic reactions, while the manganese oxide films of both nanostructure and conventional structure are electrochromically active and the effect of nanostructure on the electrochromic properties was remarkable. © 2011 Elsevier B.V. All rights reserved.

We investigated the effect of counter electrode reaction on the coloration properties of phthalate-based electrochromic (EC) cells using various counter materials. Although the coloration characteristics of dimethyl terephthalate (DMT) cells were improved using a counter material of ferrocene, an organic-based counter material could not endure the overload because of the high reduction potential of DMT. On the other hand, a DMT cell using an inorganic counter material showed good long-term switching stability. As a result, we achieved good switching stability over 5000 cycles for the phthalate-based EC cell with NiO as the counter material. © 2011 Elsevier B.V. All rights reserved.

Electrochromism is known as electrochemical reaction exhibiting coloration, and is applicable to a new imaging device. In this paper, we prepared novel modified electrode using Si coupling agent on ITO deposit. Novel modified electrode achieved better memory effect and lower coloration potential in comparison with previous modified electrode using TiO2.

Novel multicolor electrochromic (EC) device with on electrochemical silver deposition mechanism was successfully demonstrated. The novel EC device enabled reversible color change between transparent, red and blue color in a single cell by using voltage step method which controlled the size of deposited Ag nanoparticles.

Multi-functional composite film showing thermoresponsive absorption and emission was demonstrated by using thermochromic leuco dye, developer and luminescent Europium(III) complex; the coloration and bleaching of the leuco dye enabled control of the photoluminescence of the Eu(III) complex by thermal stimuli.

Electrochemiluminescence(ECL) is known as electrochemical reaction exhibiting emission, and is applicable to new imaging device. We have been studying the Emission characteristics of ECL cell containing a Ruthenium(II) complex as luminescent species. The emission turn-on response time and emission intensity were dramatically improved by introducing AC method. In this paper, we studied the phenomena of ECL cell with electroconductive polymer like as poly [2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylen] (MEH-PPV) instead of a Ruthenium (II) complex. Orange light emitted from the ECL cell of MEH-PPV with a turn-on voltage of AC 4V at 10Hz for the first time. © 2012CPST.

Electrochemiluminescence(ECL) is known as electrochemical reaction exhibiting emission, and is applicable to new imaging device. We have been studying the Emission characteristics of ECL cell containing a Ruthenium(II) complex as luminescent species. The emission turn-on response time and emission intensity were dramatically improved by introducing AC method.In this paper, we studied the phenomena of ECL cell with electroconductive polymer like as poly [2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylen] (MEH-PPV) instead of a Ruthenium (II) complex. Orange light emitted from the ECL cell of MEH-PPV with a turn-on voltage of AC 4V at 10Hz for the first time. © 2012CPST.

We studied the electrochromic (EC) and electrochemiluminescent (ECL) properties of a novel dual-mode display (DMD) cell that was enabled for reflective and emissive modes of representation by introducing both EC and ECL materials into an electrochemical cell. We fabricated EC, ECL, and DMD cells based on a simple-mixture solution or modified electrodes and compared their properties to clarify the advantage of a DMD system based on modified electrodes. Both the solution- and modified electrode-based DMDs showed EC properties in the reflective mode under dc bias application and ECL properties in the emissive mode under ac bias application. Although the solution-based DMD cell featured a very simple structure, some improvements related to side reaction and quenching reaction were required. The modified electrode-based DMD cell was fabricated to improve these aspects. The advantage of the DMD model based on the modified electrodes was certainly suggested by comparisons of the results with those of EC, ECL, and DMD cells based on a simple-mixture solution. © the Owner Societies 2011.

An organic thin-film transistor (OTFT) memory was fabricated using deoxyribonucleic acid (DNA) as a gate dielectric layer. Since natural DNA contains intrinsic ions and water molecules, the OTFT exhibited low resistivity and a low on/off ratio because of the mobile ions. In order to remove these mobile ions from DNA, it was complexed with a bulky surfactant through an electrostatic interaction. The OTFT fabricated using a DNA-surfactant complex exhibited a relatively high on/off ratio because of the decrease in the off-current. Residual ions that remained in the complex caused a decrease in the cell performance with respect to parameters such as the on/off ratio and long-term memory stability. When poly(methyl methacrylate) (PMMA) was layered on the DNA-surfactant layer, the OTFT exhibited better on-current and long-term memory stability than a typical OTFT. The pentacene layer deposited on the PMMA surface as a semiconductor had a relatively large grain size and relatively high crystallinity. This contributed to an increase in the hole mobility in the pentacene layer and the prevention of the abovementioned adverse effects of the residual ions. Consequently, the performance of the OTFT memory having the DNA complex was considerably improved. © 2011 The Royal Society of Chemistry.

We have demonstrated electroswitchable emission and coloration using a novel composite material containing luminescent europium(iii) complex Eu(hfa)3(H2O)2 and diheptyl viologen HV 2+. The photoluminescence of the Eu(iii) complex was controlled by the electrochemical coloration of HV2+via intermolecular energy transfer mechanisms. © The Royal Society of Chemistry 2011.

Externally added charge control agents (EA-CCAs) were prepared by means of a coacervation process. Spherical silica particles of 100 nm average diameter were coated with two kinds of charge control agents (CCAs); one was a polymer type P-1 and the other was a low molecular weight type P-2. Both of CCAs made remarkable contribution to toner charge. In a concentration range up to 0.2 μmol/g of CCA on toner, toner charge increased. From the relationship between the amount of EA-CCA on the toner and the tribocharge, P-2 was found more effective than P-1. It was estimated that 0.7 mol% of P-1 repeating units and 1.3 mol% of P-2 molecules contributed to toner charge, respectively. Calculation of the surface coverage of P-2 on spherical silica particles showed that the efficient concentration region of charge agreed with the 100% of surface coverage. The P-2 concentration was 0.02 μmol/g based on toner. This means that the CCA molecule has a great effect on tribocharge in small concentration. © 2011 Society for Imaging Science and Technology.

We investigated the properties of 4,4′-biphenyl dicarboxylic acid diethyl ester (PCE). The PCE underwent a 2-step reduction at -1.5 V and -2.2 V. The color of the PCE changed from colorless to yellow in the first step and consequently to red in the second reduction step. A PCE based EC cell using an NiO-modified electrode was also fabricated. The NiO electrode worked as a counter reaction material for PCE reduction. The PCE-NiO cell achieved multi-coloration ranging from colorless to yellow and red, and also achieved high coloration efficiency and long term switching stability. © the Owner Societies 2011.

An AC voltage-driven electrochemiluminescent (ECL) device containing a ruthenium(ii) complex as luminescent species was fabricated, and advantages of the AC-driven method such as electrochemical and emission response were studied. The cell can be easily fabricated by simply placing the emitting solution between electrodes. The emission turn-on response time and emission intensity were dramatically improved by introducing the AC method. The turn-on response time was speeded up by increasing applied frequency. 4 ms was achieved at 200 Hz, which was much faster than the DC method (1.5 s). The current efficiency for the emission was estimated to be 0.59 cd A-1. The mechanism of the improved ECL properties was discussed from a viewpoint of electrochemical reaction. © 2010 The Royal Society of Chemistry.

In this study, the voltage-controlled color tunability of an organic light emitting diode composed of a DNA/Polyaniline/Ru (bpy) 3 2+ complex (as the hole transport layer) and tris(8-hydroxyquinolinato)aluminum (as the electron transport layer) was demonstrated. At applied voltage of 5 V, green emission was observed from Alq3. As the voltage was increased, the emission color changed from green to yellow (14 V) to orange (16 V) and finally to red (18 V), with strong contribution of red emission from Ru (bpy) 3 2+. This color tunability of the emission was principally a result of the shift in the carrier recombination region with an increase in applied voltage. © 2010 American Institute of Physics.

Microneedle fabrication on a metal surface based on laser ablation using twisted light with spin was demonstrated, for the first time. The resulting needle showed a height of at least 10 μm above the target surface and a tip diameter of less than 0.3 μm. We also demonstrated the fabrication of a two-dimensional 5 × 6 microneedle array. The needles were uniformly well shaped with an average length and tip diameter of about 10 and 0.5 μm, respectively. © 2010 Optical Society of America.

We successfully demonstrated a novel reflective-emissive dual-mode display (DMD) cell with electrochromic and electro-chemiluminescence reactions. This DMD cell has simple structure and allows the selection of reflective or emissive mode by selecting DC or AC driving, respectively. © 2010 The Chemical Society of Japan.

The amplified spontaneous emission (ASE) properties of polymer thin-films containing Eu(III) complexes were demonstrated by observating emissions from the edge of excited polymer thin-films. The amplification of the ASE components of Eu(III) complexes was increased in proportion to the absorption cross-sections. In particular, the amplitude percentages of the ASE component of Eu(III) complexes having naphthyl groups (absorption cross-section at 355 nm: 850 × 10-19 cm2) were estimated to be over 60% under 10 mJ excitation. © 2008 Elsevier B.V. All rights reserved.

Deuterated Eu(III) complexes of tris-(hexafluoroacetylacetonato)europium(III) dehydrates (Eu(hfa-H)3(H2O)2), tris-(hexafluoroacetylacetonato)europium(III) bis(triphenylphospine oxide) (Eu(hfa-H)3(TPPO)2), tris(hexafluoroacetylacetonato) europium(III) 1,1′-biphenyl-2,2′-diylbis (diphenylphosphine oxide) (Eu(hfa-H)3(BIPHEPO)) were prepared by the exchange reaction via keto-enol tautomerism of the Eu(III) complexes with CD3OD. The emission quantum yields of the deuterated Eu(III) complexes were higher than those of corresponding non-deuterated Eu(III) complexes. The lasing properties of Eu(III) complexes in polymer thin film were measured by photo-pumping of Nd: YAG laser (355 nm). Percentages of ASE components in whole emission were increased by deuteration of the Eu(III) complexes. © 2007 Elsevier B.V. All rights reserved.

We have succeeded in the simultaneous photoluminescence in the two colors, red and green, from a single nano-sized zeolite crystallite containing Eu(III) and Tb(III) as exchanged cations in a cavity through photosensitization by an organic photosensitizer (benzophenone). Paths of energy transfer from Eu(III) ions to Tb(III) ions and from Tb(III) ions to Eu(III) ions have been revealed in addition to the primary energy transfer from the excited triplet state of the photosensitizer to both cations. © 2007 Elsevier B.V. All rights reserved.

Near-IR emission of novel Yb(III) complexes with phenanthroline derivertives, bis(phenanthroline)-tris(bis-perfluoromethanesurfonyliminate) ytterbium [Yb(pms)3(phen)2] and dipyridophenazine- tris(bis-perfluoromethanesurfonyliminate)ytterbium [Yb(pms)3(dip)] are studied in dimethylsulfoxide [DMSO-d6]. The emission quantum yields of Yb(pms)3(phen)2 and Yb(pms)3(dipy- phenazine) excited at 940 nm (2F7/2-2F 5/2 transition) were found to be 7.4 and 9.1%, respectively. We successfully observed the photosensitized near-infrared emission from the Yb(III) complexes upon excitation of the aromatic ligands. The energy transfer efficiencies of Yb(pms)3(phen)2 and Yb(pms) 3(dip) excited at 310nm (π-π* transition) were evaluated to be 9.1 and 4.0%, respectively. © 2008 The Japan Society of Applied Physics.

The luminescent and lasing properties of Eu(III) complexes were enhanced by using an dissymmetric Eu(III) complex. The photophysical properties (the emission spectral shapes, the emission lifetimes, the emission quantum yields, and the stimulated emission cross section (SEC)) were found to be dependent on the geometrical structures of Eu(III) complexes. The geometrical structures of Eu(III) complexes were determined by X-ray single crystal analyses. The symmetrical group of Eu(hfa)3(BIPHEPO) (tris(hexafluoroacetylacetonato)-europium(III) 1,1′-biphenyl-2,2′- diylbis(diphenylphosphine oxide)) was found to be C1, which was more dissymmetric than Eu(hfa)3(TPPO)2 (tris(hexafluoroacetylacetonato)europium(III) 1,2-phenylenebis(diphenylphosphine oxide): C2 symmetry) and Eu(hfa)3(OPPO)2 (tris(hexafluoroacetylacetonato)europium(III) 1,2-phenylenebis(diphenylphosphine oxide): C2 symmetry). The analytical data were supported by Judd-Ofelt analysis. The most dissymmetrical Eu(III) complex, Eu(hfa) 3(BIPHEPO), showed large electron transition probability and large SEC (4.64 × 10-20 cm2). The SEC of Eu(hfa) 3(BIPHEPO) was superior to even the values of Nd-glass laser for practical use (1.6-4.5 × 10-20 cm2). The lasing properties of Eu(III) complexes in polymer thin film were measured by photopumping of a Nd: YAG laser (355 nm). The threshold energy of lasing oscillation was found to be 0.05 mJ. The increasing rate of the lasing intensity of Eu(hfa)3(BIPHEPO) as a function of the excitation energy was much larger than that of Eu(hfa)3(TPPO)2 and Eu(hfa) 3(OPPO)2. The dissymmetrical structure of Eu(hfa) 3(BIPHEPO) promoted the enhancement of the lasing property. © 2007 American Chemical Society.

Luminescent Eu(III) complexes with bis-phosphine oxide ligands were synthesized. Geometric structures of novel Eu(III) complexes were determined by single-crystal X-ray diffraction. One of the Eu(III) complexes showed remarkably sharp red emission and large stimulated emission cross-section (full width at half maximum (FWHM) = 2.1 nm, stimulated emission cross-section = 1.80 × 10-20 cm2). The sharpness of the emission bands of the Eu(III) complexes was discussed in terms of the symmetry of the geometrical structure. © 2005 Elsevier B.V. All rights reserved.

Luminescent polymer (PMMA) containing a Eu(III) complex with a fast radiation rate and a high luminescence quantum efficiency (75 ± 5%), (bis-triphenylphosphineoxide)(tris-hexafluoroacetylacetonato)europium(III) (Eu(hfa)3(TPPO)2), was fabricated. The quantum yield and the radiation rate of the luminescent polymer were found to be 75 ± 5% and 1.1 × 103 s-1, respectively. An Eu(III) complex-doped polymer thin-film was also prepared by use of polyphenylsilsesquioxane (PPSQ) to construct a waveguide lanthanide laser. We propose a strategy for the molecular design of luminescent Eu(III) complexes aiming at lanthanide lasing. © 2005 Elsevier B.V. All rights reserved.

In order to fabricate a high-power laser medium using Eu(III) complex, strong-luminescent Eu(III) complexes with low vibrational ligands were synthesized. One of the Eu(III) complex showed remarkably sharp red emission and large stimulated emission cross-section. The value of stimulated emission cross-section was the same order as the values of Nd-glass laser for practical use. © 2004 Elsevier B.V. All rights reserved.

Polythiophene-sensitized, nanocrystalline TiO2-based photoelectrochemical cells were fabricated either by using poly(3-thiophene acetic acid) (P3TAA) or a co-polymer; poly(3-thiophene acetic acid)-poly(hexyl thiophene) (P3TAA-PHT) polymers and their performances were examined. The photocells were able to generate reasonably high photocurrent, which increases in the presence of the electron-donating ionic liquids in the electrolyte composed of redox couple I3-/I-. Dramatic enhancements in the cell performances were observed with the addition of ionic liquid 1-methyl-3- n -hexylimidazolium iodide into the electrolyte. While the cell sensitized with P3TAA generated a short-circuit photocurrent of ∼9.75 mA cm-2, an open-circuit photovoltage of ∼405 mV and a total power conversion efficiency of ∼2.4% under simulated full sunlight of 100 mW cm-2 (air mass 1.5) the cell sensitized with copolymer P3TAA-PHT delivered ∼1.6% efficiency under the same conditions with ∼7 mA cm-2 as photocurrent and ∼375 mV as photovoltage. The corresponding incident photon-to-current conversion efficiencies (IPCE) of the above cells were ∼60 and ∼40%, respectively. © 2004 Elsevier B.V. All rights reserved.

We prepared novel pyrene-fused porphyrins via the oxidative intramolecular ring closure reactions of meso-pyrenylporphyrin. The excitation energies and the oxidation potentials of the isolated dark-colored pyrene-fused porphyrins were significantly low compared with those of the corresponding precursors.

Poly(3-thiophenylacetic acid)-polymer-sensitized photoelectrochemical cells comprising of either mesoporous TiO2 or SnO2-ZnO electrodes and the electrolyte consisting with redox complex (I-3(-)/I-) were fabricated and characterized. The addition of ionic liquid, 1-methyl- 3-n-hexylimidazolium iodide, into the electrolyte drastically enhanced the cell performance. The cells consisting of the nanoporous TiO2 electrodes showed the incident photon to current conversion efficiency as high as 60% (at 430 nm), while the highest overall power conversion efficiency was similar to2.4% under the irradiance of 100 mW cm(-2) (air mass 1.5). The overall efficiency of the cells with nanoporous SnO2-ZnO electrodes was similar to1.5% under the same illumination. (C) 2003 American Institute of Physics.