High efficiency blue organic LEDs achieved by an integrated fluorescence-interlayer-phosphorescence emission architecture

Abstract

This paper presents a new strategy to develop efficient organic light-emitting devices (OLEDs) by doping fluorescent- and phosphorescent-type emitters individually into two different hosts separated by an interlayer to form a fluorescence-interlayer-phosphorescence (FIP) emission architecture. One blue OLED with FIP emission structure comprising p-bis(p-N,N- diphenylaminostyryl)benzene (DSA-Ph) and bis[(4,6-di-fluorophenyl)-pyridinate-N, C2']picoIinate (Flrpic) exhibiting a peak luminance efficiency of 15.8cdA-1 at 1.54 mA cm-2 and a power efficiency of 10.2 lm W-1 at 0.1 mA cm-2 is successfully demonstrated. The results are higher than those of typical phosphorescent OLEDs with a single emission layer by 34% and 28%, respectively. From experimental and theoretical investigations on device performance, and the functions of the used emitters and interlayer, such enhancement should ascribe to the appropriate utilization of the two types of emitters. The fluorescent emitter of DSA-Ph is used to facilitate the carrier transport, and thus accelerate the generation of excitons, while the phosphorescent emitter of Flrpic could convert the generated excitons into light efficiently. The method proposed here can be applied for developing other types of red, green, and white OLEDs. © 2010 WILEY-VCH Verlag GmbH & Co. KGaA.