The Characteristics and Device Applications for OLED Carrier-Transporting Materials and Emitting Materials

• Main Authors: Chung-Chia Chen, 陳重嘉
• Other Authors: Chung-Chih Wu
• Format: Others
• Language: en_US
• Published: 2010
• Online Access: http://ndltd.ncl.edu.tw/handle/51947459457190519160

博士 === 國立臺灣大學 === 電機工程學研究所 === 99 === In this dissertation, we studied fundamental properties and device architectures for organic light-emitting devices (OLEDs). First, the impedance spectroscopy was adopted to investigate the p-type conductively doped hole transporting layer and to construct equivalent circuits. Because of the addition of conductive dopant, it was found necessary to take account the difference between the bulk region and the depletion region near the electrode, and dispersion (i.e. frequency dependence) in the dielectric response of the conductively doped transport layer. As such, it is found necessary to include the non-conventional complex impedance element in the equivalent circuit to achieve tight matching of simulated results The second part of the dissertation is about the simplification of OLED device structure. By the aid of the novel host material possessing bipolar transporting capability and high triplet energy, we successfully fabricated efficient single-layer phosphorescent OLEDs Efficient blue and white single-layer phosphorescent OLEDs were demonstrated. Furthermore, we again adopted the same host material to fabricate conventional multi-layer OLEDs. With only adding a hole-transporting layer and an electron-transporting layer to form a relatively simple three-layer simple structure, very efficient blue and white phosphorescent OLEDs were implemented with small efficiency roll-off. Finally, we utilized novel Ir-based blue and red phosphors to fabricated efficient white phosphorescent OLEDs (WOLEDs) for solid state lighting (SSL). With carefully designed device architectures, we achieved efficient phosphorescent WOLEDs with high color rendering index over a wide luminance range.