有機EL素子における電気伝導の温度特性とキャリア挙動

概要

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Organic Electroluminescent device (OLED) was fabricated using a vacuum evaporation method and thermal properties were investigated. The OLED has an Indium Tin Oxide (ITO)/ N,N-diphenyl-N,N- bis(3-methylphenyl) 1- 1biphenyl- 4,4-diamine (TPD)/ tris- (8-hydroxyquinoline) aluminum (Alq)/ Lithium fluoride (LiF)/ aluminum (Al) structure. An electron dominant device of an Al/ Alq/ LiF/ Al structure, or a hole dominant device of an ITO/ TPD/ Al structure was also fabricated in order to study the carrier behavior in the OLEDs. The current density vs. voltage (J-V) properties with various thickness of organic layers were investigated in the both electron and hole dominant devices, and the thermal dependence of J-V properties was observed in the devices. At room temperature, conductions in large current region were considered to be due to space-charge-limited current for all the devices. Especially, for the Al/ Alq/ LiF/ Al device and the OLED, J∝Vm+1 relationships were observed across wide current region. At low temperature, tunnel currents were estimated for the ITO/TPD/Al device. For the Al/ Alq/ LiF/ Al device and the OLED, J∝Vm+1 relationships were observed across wide current region at low temperature.
2007-10-01