Masao Uchida

Blue Electroluminescent Diodes Utilizing Poly(alkylfluorene)

Blue electroluminescent diodes utilizing poly(alkylfluorene) have been demonstrated for the first time. A Schottky-type electroluminescent diode of poly(9,9-dihexylfluorene) is driven at ~10 V and has a peak emission wavelength of 470 nm at room temperature.

Visible-Light Electroluminescent Diodes Utilizing Poly(3-alkylthiophene)

A visible-light electroluminescent diode utilizing poly(3-alkylthiophene) has been demonstrated for the first time. The light emission intensity increases superlinearly with increasing injected current. Remarkable enhancement of electroluminescence intensity is obtained for a poly(3-alkylthiophene) diode with longer alkyl side chain length.

Effects of | alkyl chain length and carrier confinement layer | on characteristics of poly(3-alkylthiophene) electroluminescent diodes

Abstract Visible poly(3-alkylthiophene) electroluminescent diodes with carrier confinement layer have been demonstrated for the first time. The light emission intensity increases drastically with introducing carrier confinement layer. Anomalous characteristics have been found in current-light intensity characteristics of the electroluminescent diodes. Remarkable enhancement on electroluminescence intensity has been obtained for poly(3- alkylthiophene) diodes with longer alkyl side chain length.

Fabrication and characteristics of 8‐hydroxyquinoline aluminum/aromatic diamine organic multiple quantum well and its use for electroluminescent diode

Multiple quantum well structure consisting of alternating layers of organic 8‐hydroxyquinoline aluminum (Alq3) and aromatic diamine (TPD) has been grown by organic molecular beam deposition. The multiple quantum well structure was determined by x‐ray diffraction, optical absorption, and photoluminescence. Photoluminescence peak of Alq3 shifts to higher energy with decreasing layer thickness, suggesting a quantum size effect. An electroluminescent diode has also been fabricated by using Alq3/TPD multiple quantum well structure.

Observation of spectral narrowing and emission energy shift in organic electroluminescent diode utilizing 8‐hydroxyquinoline aluminum/aromatic diamine multilayer structure

Organic electroluminescent (EL) diode with a multilayer structure which consists of alternating layers of organic 8‐hydroxyquinoline aluminum (Alq3) and aromatic diamine has been grown by organic molecular beam deposition. The EL emission from the multilayer structure shows spectral narrowing and the emission energy has been observed to shift to higher energy compared with that in the monolayer structure. Mechanism of spectral narrowing and the emission energy shift in the diode with the multilayer structure have been discussed.

Color-Variable Light-Emitting Diode Utilizing Conducting Polymer Containing Fluorescent Dye

A color-variable light-emitting diode has been realized utilizing conducting polymer, poly(2,5-dioctyloxy-p-phenylene vinylene) (ROPPV-8), mixed with fluorescent dye, 8-hydroxyquinoline aluminum (Alq3). The electroluminescence of the diode changes from orange to greenish-yellow in color with increasing applied voltage. On the other hand, a light-emitting diode with the two-layer structure of ROPPV-8 and Alq3 shows only light emission from the ROPPV-8 layer. This difference is discussed in terms of the carrier injection process to Alq3.

Visible and blue electroluminescent diodes utilizing poly(3-alkylthiophene)s and poly(alkylfluorene)s

Abstract Visible red-orange poly(3-alkylthiophene) and blue poly(alkylfluorene) electroluminescent diodes have been successfully fabricated and the emission characteristics of the diode have been discussed. The electroluminescent diodes consist of thin polymer films sandwiched by ITO and Mg alloy electrodes. The dependence of emission intensity on alkyl-side-chain shows that the longer the alkyl-side-chain length is, the stronger the emission intensity of poly(3-alkylthiophene) diode is. The diode emits red-orange light having a broad band peaked at 640 nm, which correspond to the band gap of the poly(3-alkylthiophene). Novel temperature dependence of electroluminescence intensity has also been discussed. Blue emission centered at 470 nm have also been observed in poly(alkylfluorene) diode. Band diagrams of the electroluminescent diodes have also been discussed.

Fabrication and Characteristics of Schottky Gated Poly(3-alkylthiophene) Field Effect Transistors

Fabrication and characterization of Schottky gated poly(3-alkylthiophene) field effect transistors have been reported. The transistors have been realized using free-standing poly(3-alkylthiophene) films with Schottky gated electrode configuration with low drive voltages. From the FET characteristics, the carrier mobility is evaluated to be 3×10-3 cm2/Vs.

Innate form of HCV core protein plays an important role in the localization and the function of HCV core protein

Hepatitis C Virus (HCV) has been identified as the major causative agent of non-A, non-B hepatitis. Core protein is not only a capsid protein of HCV but also a regulator of cellular functions, and plays an important role in the pathogenesis of HCV. Core protein is produced as an innate form (amino acids [a.a.] 1-191), and following processing produces a mature form (a.a. 1-173). This study demonstrates that the innate form regulates subcellular localization of the mature form, and that the innate form in the cytoplasm enhances p21 expression; on the other hand, the mature form in the nucleus suppresses p21 expression. These observations suggest that the innate form is not only a precursor of the mature form but also a regulator of the localization and functions of core protein.

Time-resolved pulse response of electroluminescence in poly(3-alkylthiophene) diodes

Pulse response of electroluminescence in poly(3-alkylthiophene) diodes has been investigated. The response consists of two independent parts, that is, fast and slow transition parts. The fast response corresponds to carrier transit between electrodes. On the other hand, the anomalous slow response which becomes marked at higher current is explained by the temperature change of the diode junction. Carrier mobility of the poly(3-alkylthiophene) has been estimated from the fast part, which coincides with that evaluated from the characteristics of poly(3-alkylthiophene) field-effect transistors. Temperature dependence of the electroluminescence intensity in poly(3-alkylthiophene) diode has been discussed.