Takayuki Taneda

Realization of polymeric optical integrated devices utilizing organic light-emitting diodes and photodetectors fabricated on a polymeric waveguide

Direct fabrication of organic light-emitting diodes (OLEDs) and organic photodetectors (OPDs) on polymeric substrates, i.e., polymeric waveguide substrates to form flexile optical integrated devices is demonstrated. The OELD and OPD were fabricated by organic molecular beam deposition (OMBD) technique on a polymeric or a glass substrate, for comparison. The device fabricated on a polymeric substrate shows similar device characteristics to that on a glass substrate. Optical signals of faster than 100 MHz have been created by applying pulsed voltage directly to the OLED utilizing diamine derivative, or rubrene or porphine doped in 8-hydoxyquinolinum aluminum derivatives, as an emissive layer. Electrical signals are successively converted to optical signals for optical transmission of moving picture signals with OLED fabricated on a polymeric waveguide. OPDs utilizing phthalocyanines derivatives with superlattice structure provide increased pulse response with input optical signals, and the OPD with the cutoff frequency of more than 5 MHz has been realized.

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.

Organic light-emitting diode fabricated on a polymer substrate for optical links

An organic electroluminescence diode (OLED) fabricated on polyimide substrate has been investigated to realize a flexible electro-optic device for optical links. The device fabricated on polyimide substrate shows similar device characteristic to that on glass substrate. The modulation performance of the OLED was significantly improved by applying a positive, low-level DC bias, which results in a slower falling time. An undershoot voltage applied to the falling edge of the input voltage pulse results in faster falling time and a decrease in intensity of the optical output. We demonstrate that the OLEDs can be applied to short-range optical communication fields, such as electro-optical conversion devices for optical links.

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 Diode Fabricated on Indium-Tin-Oxide-Coated Polyimide Substrate as an Electro-optical Conversion Device for Polymeric Waveguides

An organic electroluminescence diode (OLED) fabricated on a polyimide substrate has been investigated for generating high-speed optical pulses at lower voltages. The OLED fabricated on a polyimide substrate shows similar device characteristics to those on a glass substrate. The modulation performance of OLED was improved significantly by applying a positive low dc bias at low voltages. The overshoot voltage applied on the rising edge of the input voltage pulse results in a faster rise time of the optical output. The undershoot voltage applied on the falling edge of the input voltage pulse results in a faster fall time and a decrease in the intensity of the optical output. Optical pulses of 100 MHz have been obtained from an OLED with rubrene doped in 8-hydroxyquinoline aluminum as an emissive layer with an active area of 0.01 mm2 fabricated on an indium-tin-oxide-coated polyimide substrate.

HIGH-SEED OPERATION OF ORGANIC ELECTROLUMINESCENT DIODES AND PHOTO-DETECTORS FOR APPLICATION OF OPTICAL INTEGRATED DEVICES

Organic electroluminescent diode (OELD) has been investigated for use as a light source of polymeric optical integrated devices. The OLED was fabricated by organic molecular beam deposition (OMBD) technique. The OLEDs were fabricated on both glass and polymeric substrates. The device fabricated on a polymeric substrate shows similar device characteristics to those on a glass substrate. Optical signals of faster than 100 MHz has been created by applying pulsed voltages directly. Optical photo detectors (OPDs) utilizing phthalocyanine superlattice structure provide increased pulse response with optical signals and have response for optical pulse of faster than 1 MHz.

Optical properties of Zn(II) complex using 1,2-bis(8-hydroxyquinolin-2-yl)ethane

Optical properties of Zn(II) complex using 1,2-bis(8-hydoxyquinolin-2-yl)ethane (Zn(BQOEH)), such as optical absorption, photoluminescence, and electroluminescence, are studied. Zn complex film emits a yellow photoluminescence band centered at 564 nm and an electroluminescence band at 567 nm. Transient characteristic of the organic light-emitting devices (OLEDs) with Zn(BQOEH) as the emitting material are demonstrated. An optical pulse of more than 5 MHz is obtained from the OLED with Zn(BQOEH).