High-efficiency, low-voltage phosphorescent organic light-emitting diode devices with mixed host

被引：140

作者：

Kondakova, Marina E. ^{[1
]}

Pawlik, Thomas D. ^{[1
]}

Young, Ralph H. ^{[1
]}

Giesen, David J. ^{[1
]}

Kondakov, Denis Y. ^{[1
]}

Brown, Christopher T. ^{[1
]}

Deaton, Joseph C. ^{[1
]}

Lenhard, Jerome R. ^{[1
]}

Klubek, Kevin P. ^{[1
]}

机构：

[1] Eastman Kodak Co, Rochester, NY 14650 USA

来源：

JOURNAL OF APPLIED PHYSICS | 2008年 / 104卷 / 09期

关键词：

D O I：

10.1063/1.3000046

中图分类号：

O59 [应用物理学];

学科分类号：

摘要：

We report high-efficiency, low-voltage phosphorescent green and blue organic light-emitting diode (PHOLED) devices using mixed-host materials in the light-emitting layer (LEL) and various combinations of electron-injecting and electron-transporting layers. The low voltage does not rely on doping of the charge-transport layers. The mixed LEL architecture offers significantly improved efficiency and voltage compared to conventional PHOLEDs with neat hosts, in part by loosening the connection between the electrical band gap and the triplet energy. Bulk recombination in the LEL occurs within similar to 10 nm of the interface with an electron-blocking layer. A "hole-blocking layer" need not have hole- or triplet-exciton-blocking properties. Optical microcavity effects on the spectrum and efficiency were used to locate the recombination zone. The effect of layer thickness on drive voltage was used to determine the voltage budget of a typical device. The behavior of undoped devices was investigated, and the electroluminescence is attributed to an exciplex of the two host materials. Electrically detected electron paramagnetic resonance was used to study the behavior of doped and undoped PHOLED devices from 20 to 200 K, which largely mimics the behavior of the same devices at room temperature. (C) 2008 American Institute of Physics. [DOI: 10.1063/1.3000046]

引用

页数：17

共 62 条

[1] Efficient electrophosphorescence using a doped ambipolar conductive molecular organic thin film [J].