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This study focused on the performance of solution-processed multilayer polymer light-emitting diodes (PLEDs) with both the hole and electron transport layers using poly(9,9-dioctylfluorene-co-benzothiadiazole) (F8BT) as an active layer. By insertion of both the hole and electron transport layers, improved emission and transient characteristics were achieved for the electro-optical conversion devices. For the multilayer device, the maximum current efficiency of 2.2 cd/A and the short response times of electroluminescence (ca. 30 ns) were achieved. [ABSTRACT FROM PUBLISHER]

The emission characteristics and transient electroluminescence (EL) of organic light-emitting diodes (OLEDs) using tris(8-hydroxyquinolinato)aluminum (Alq3) as an emissive layer with LiF/Al cathode and LiF doped Al composite cathode (LiF:Al alloy cathode) were investigated. A device with LiF:Al (1:10) alloy cathode showed the maximum current efficiency of 4 cd/A. The emission characteristics of this device were almost the same as that with LiF/Al cathode. Rise time of the device with LiF:Al alloy cathode was shorter than that of a device with LiF/Al cathode, because the waveform rounding of current density occurred for the device with LiF/Al cathode. [ABSTRACT FROM PUBLISHER]

The influence of ultraviolet (UV) irradiation on carrier conduction and emission characteristic of the top-gate-type ambipolar organic field-effect transistors (OFETs) utilizing crystallized poly(9,9-dioctylfluorene) (F8) films were investigated. For a device with irradiated UV light, only p-type conduction was exhibited and the hole field-effect mobility was almost the same as that without UV irradiation. As a result, the EL emission was not observed owing to the decrease of n-type conduction after UV irradiation. It is suggested that the quenching center which is generated in F8 film by UV irradiation is greatly related to the electron trap site of OFETs. [ABSTRACT FROM PUBLISHER]

This study focuses on the performance of organic light-emitting diodes (OLEDs) using an emissive material with high hole drift mobility, tris[4-(5-phenylthiophen- 2-yl)]amine (TPTPA), which exhibits the highest level of hole drift mobility (1.0 × 10-2 cm2 V-1 s-1) among those reported for organic disordered systems. Clear blue emission was observed from TPTPA which was used as the hole transporting and emissive layer in the OLEDs. The maximum luminance of 1.2 × 104 cd/m2, and the maximum current efficiency of 3.9 cd/A were achieved. The short response times of electroluminescence (ca. 10 ns) were achieved under the application of rectangular-shaped voltages. [ABSTRACT FROM AUTHOR]

The effect of electron injection in polymer light-emitting diodes based on the phosphorescent material of fac-tris(2-phenylpyridine) iridium (Ir(ppy)3) devices with CsF/MgAg/Ag cathodes were investigated. The device with MgAg (1 nm)/CsF (3 nm)/Ag cathode showed almost similar current density-voltage-luminance characteristics to that with CsF (3 nm)/MgAg (1 nm)/Ag cathode. The existence of interface between the organic layer and Cs or CsF results in low turn on voltage. To achieve the efficient electron injection and the low turn on voltage, it is necessary to exist MgAg and CsF interface at the position of about 1 nm from organic layer. To achieve the efficient electron injection, it is necessary to exist Cs layer just on the organic layer. The electron injection effects between devices with CsF and Cs are different. It is suggested that the dipole of CsF affect the efficient electron injection. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]