Takahisa Tsukagawa

Transient Properties of Organic Electroluminescent Diode Using 8-Hydroxyquinoline Aluminum Doped with Rubrene as an Electro-Optical Conversion Device for Polymeric Integrated Devices

We describe modulation characteristics of organic light-emitting diodes (OLEDs) using 8-hydroxyquinoline aluminum (Alq3) as an electro-optical conversion device for polymeric integrated devices. Optical pulses of more than 100 MHz were created by directly modulating a yellow emitting OLED with rubrene doped in Alq3 as an emissive layer which has the advantages of low propagation loss in the polymer waveguide and high emission intensity. We demonstrate that the OLEDs can be applied to fields of optical communication as electro-optical conversion devices for transmitting the signals of moving images.

Fast Response of Organic Photodetectors Utilizing Multilayered Metal-Phthalocyanine Thin Films

Multilayered photodetectors have been fabricated by using metal phthalocyanines as hole and electron transporting layers. From the dark and photocurrent density and applied voltage characteristics, the open-circuit voltage and short-circuit current density for the 5 periods of multilayered photodetector are about 0.3 V and 0.2 mA cm-2, respectively. The photoresponse, irradiating pulsed light with the wavelength of 640 nm, has also been measured. The photogenerated excitons dissociate to free holes and electrons by relatively rapid charge transfer across closely stacked organic layer interfaces. The 3 dB bandwidth of the device has been improved by applying a reverse bias field to the device and by decreasing the individual photo-absorbing layers while keeping the total layer thickness constant. A cutoff frequency of 1 MHz has been obtained for 5 periods of multilayered titanyl phthalocyanine/fluorinated zinc phthalocyanine photodetector by applying a reverse bias voltage of -5 V.

Organic electroluminescent diodes as a light source for polymeric waveguides - toward organic integrated optical devices

Abstract We fabricated organic electroluminescent diodes (OELD) on a polymeric optical waveguide for use as an optical interconnect in data communication systems. We fabricated the OELDs on an ITO sputtered polymeric waveguide with a 45° mirror by vacuum deposition. These OELDs, with an emission peak center at 520 nm, consist of a N,N′-diphenyl-N,N′-(3-methylphenyl)-1,1′-biphenyl-4,4′-diamine (TPD) as a hole transporting layer and 8-hydroxyquinolie aluminum (Alq3) as an emissive layer. We estimated the propagation losses of the waveguide to be 1.35 dB/cm at 520 nm. The optical pulses of faster than 5 Mb/s have been generated from the OELD. We discuss the characteristics of the OLED as regards its use as a light source for polymeric waveguides.

Organic electroluminescent diodes as a light source for polymeric integrated devices

Organic electroluminescent diodes (OLED) were fabricated on a polymeric optical waveguide for use as an optical interconnector in data communication systems. The OLED were fabricated on an ITO sputtered polymer waveguide with a 45 degree mirror by vacuum deposition. The OLEDs, with an emission peak center at 520 nm consist of diamine derivative as a hole transporting layer and tris(8-hydroxyquinoline) aluminum (Alq3) as an emissive layer. We estimated the propagation losses of the waveguide to be 1.35 dB/cm at 520 nm. However, it decreases as increasing the wavelength of the light source and is estimated as 0.37 dB/cm at the wavelength of 614 nm. The optical pulse of more than 5 Mb/s has been obtained from the OLED with Alq3 and diamine derivative. We discuss the properties of the OLED for the light source for polymeric integrated devices.

High Intensity Blue Light EL Device Using Heterostructure of p-Sexiphenyl and TPD

Abstract Enhanced electroluminescence (EL) from vapor deposited p-sexiphenyl (6p) layer has been observed utilizing heterostructure of p-sexiphenyl emissive layer and N,N′-diphenyl-N,N′-(3-methylphenyl)-1,1′-biphenyl-4,4′-diamine (TPD) hole transporting layer. The device emits blue light centered at 420 nm, and the EL intensity reaches as high as 3,400 cd/m2 at an applied voltage of 10 V. The heterostructure device emits 2 orders of magnitude higher intensity than the conventional single layer device.