Katsuaki Kaifu

Near‐infrared sensitive electrophotographic photoconductors using chloroindium chlorophthalocyanine

Layered electrophotographic photoconductors using chloroindium chlorophthalocyanine have been investigated. An evaporated film of chloroindium chlorophthalocyanine has a broad and strong light absorption band in the visible to near‐infrared region and its crystal structure is very stable. The photoconductor using chloroindium chlorophthalocyanine as a carrier generation layer and polyvinylcarbazole as a carrier transport layer is highly sensitive in a wide spectral region (500–900 nm) without any special treatment during its preparation. The typical value of sensitivity is 2.5 cm2/μJ at 800–900 nm, so that this photoconductor is most suitable for a laser printer equipped with a AlGaAs laser diode.

Electroluminescent properties of a Eu-complex doped in phosphorescent materials

Electroluminescent spectra of thin films in which a Eu(III)-β-diketonate complex is doped into a phosphorescent layer have been investigated. At low temperatures (77 K), the spectra consist of emissions both from the triplet excited levels of the phosphorescent material and from the 5D0 and 5D1 levels of the Eu3+ ion. In contrast, electroluminescent spectra from the Eu complex at room temperature and photoluminescent spectra from the Eu complex consist predominantly of emissions from the 5D0 level. Furthermore, the electroluminescent spectra at room temperature depend on the host materials. Energy transfer from triplet states of the phosphorescent materials to the ligand triplet state of the Eu complex and emission saturation of the Eu3+ ion at a higher level of current-injection are discussed.

Synthesis and luminescent properties of europium complexes

Abstract Europium (Eu) complexes with β -diketone ligands have been synthesized and characterized using luminescence spectroscopy. Complexes with fluorene show high fluorescence in THF solution and exhibit sharp emission peak at 615 nm. We have improved the energy transfer from the blue-emitting material (host) to the Eu complex (guest) by the synthesis of a new Eu complex which exhibits an absorption peak at lower energy with respect to the emission energy of the host. With respect to volatility, since some thin films of the complexes were not formed easily by vapour deposition, we have examined the thermal properties of the Eu complexes with phenanthroline derivatives. We discuss the efficiency of the energy transfer and volatility of these complexes.

Second harmonic generation from mixed Langmuir-Blodgett films of N-acyl-p-nitroaniline and its homologous amphiphile

Abstract Mixed Langmuir-Blodgett multilayers of N -acyl- p -nitroaniline and its homologous amphiphile, p -alkylaminophenylacetic acid, show second harmonic generation in Y-type films. The second harmonic output was anisotropic to the dipping direction, and depended on the molecular-chain lengths of the mixture. As a model of noncentrosymmetric structure in the Y-type film, the “herringbone”-like arrangement of interlayer molecules was considered. This arrangement of molecules was confirmed by measurements of second harmonic fringing patterns from heterostructural films with different combination of active and inactive layers.

Development of a Technique for Microimmobilization of Proteins on Silicon Wafers by a Streptavidin−Biotin Reaction

In order to enable the future construction of molecular devices made of functional proteins, we have developed a technique for microimmobilization of proteins into organized patterns on a silicon wafer. A specific binding reaction between streptavidin and biotin forms the basis of our method. Active and inactive biotin regions were created on a silicon wafer using a photolithographic technique. Circuit‐type patterns and 0.75/1.5 μm line‐and‐space patterns of a model fluorescent protein, B‐phycoerythrin, were successfully created on a silicon wafer.

A novel diamine compound containing carbazole groups for organic electroluminescent devices

Abstract We have synthesized a novel diamine compound (DCA) containing carbazole groups. The compound has an electron-transport ability and a high thermal stability, and a high ionization potential ( Ip ). Green-emitting electroluminescent (EL) devices with the compound as a hole-blocking material have been fabricated. The luminance of the device achieved 10000 cd/m 2 and the EL efficiency was improved. Devices capable of emitting bright green, blue, or red emissions with DCA as an electron-transport layer have been fabricated.

Second-Harmonic Generation from Y-Type Deposition of N-Acyl-p-Nitroaniline Langmuir-Blodgett Films

The second-order nonlinear optical properties of Y-type-deposited N-acyl-p-nitroaniline Langmuir-Blodgett films are studied. The second-harmonic intensity from the film shows a large anisotropy in the dipping direction and is dependent on the acyl-chain length. The same kind of anisotropy and dependence is observed in UV absorbance. It is indicated that the orientation of the p-nitroaniline group in the molecule is changed by the chain length by means of X-ray diffraction and IR spectroscopy.

Morphology in Langmuir-Blodgett multilayers of nitroaniline derivative-fatty acid mixtures

Abstract Mixed multilayers of long-chain derivatives of p -nitroaniline with arachidic acid as the supporting matrix were evaluated by morphological observation with a scanning electron microscope. The derivatives such as N -stearyl- p -nitroaniline, N -stearoyl- p -nitroaniline (sto-pNA), N -oleyl- p -nitroaniline and 2-stearyloxy-4-nitroaniline were examined. Among these multilayers, only the mixed multilayer of sto-pNA with arachidic acid exhibited a flat surface morphology. In sto-pNA mixed multilayers, sto-pNA molecules can be homogeneously mixed with arachidic acid and the alkyl chains aligned normal to the substrate according to the pressure-area isotherms and the optical absorption spectra.

Molecular rearrangement in heat-treated Langmuir-Blodgett films of mixtures of N-acyl-p-nitroaniline and fatty acid monitored by second-harmonic generation

Abstract A molecular rearrangement was monitored as an induction of second-harmonic generation (SHG). Mixed Langmuir-Blodgett films of N-acyl-p-nitroaniline and fatty acid showed SHG after heat treatment below the melting point. Studies on interference patterns of second harmonics, UV-visible absorption spectra, electron micrographs and X-ray diffraction patterns revealed that molecular rearrangement resulting from molecular movement occurred in heat-treated films. The effect of alkyl chain length of the mixing molecules was measured as an example of this monitoring method.

Application of diazonaphthoquinone compounds and a diazonium salt to contrast enhanced lithography

New photobleachable materials, two kinds of diazonaphthoquinone compounds and a diazonium salt, have been developed for contrast enhanced lithography. These materials are quite soluble in nonpolar solvents and are stable even in solution. Therefore, they can be directly coated on a bottom resist layer and removed without attacking it. Their films have strong absorption bands in the UV region involving g‐, h‐, and i‐lines. They are uniformly bleached by UV exposure. When these materials employ as contrast enhancement layers, 1.0 μm line and space patterns are clearly resolved by using a mirror projection aligner and 0.55 μm line and space patterns are clearly resolved by using an i‐line reduction projection aligner.