Bipolar material with spiro-fluorenyl terminals: synthesis, characterization and application for enhancement of electrophosphorescence
作者:Chia-Shing Wu、Juin-Wei Wu、Yun Chen
DOI:10.1039/c2jm35490j
日期:——
We have designed a novel bipolar material (FTzCz) consisting of spiro-fluorenyl terminals and a bipolar core to enhance emission efficiency of phosphorescent light-emitting diodes based on a conventional poly(9-vinylcarbazole) host and Ir(ppy)3 dopant. The core is composed of directly linked hole-transporting carbazolyl and electron-affinitive aromatic 1,2,4-triazolyl groups. The bipolar FTzCz was synthesized by the Suzuki coupling reaction and was well characterized. It exhibited not only good thermal stability due to its rigid and non-planar chemical structure, but also facilitated hole- and electron-affinities simultaneously. Blending the bipolar FTzCz with PVK significantly enhanced the performance of electrophosphorescent devices [ITO|PEDOT:PSS|(PVK + FTzCz):Ir(ppy)3 (4 wt%)|BCP (10 nm)|Ca (50 nm)|Al (100 nm)]. The maximum luminance and maximum luminance efficiency were enhanced from 3550 cd m−2 and 5.6 cd A−1 (neat PVK-based device) to 4510 cd m−2 and 9.9 cd A−1 (blend device with PVK : FTzCz = 8 : 2), respectively. Our results demonstrate the efficacy of the bipolar FTzCz in enhancing performance of electrophosphorescent devices.
我们设计了一种新型双极材料(FTzCz),它由螺芴基端和双极内核组成,可提高基于传统聚(9-乙烯基咔唑)宿主和 Ir(ppy)3 掺杂剂的磷光发光二极管的发射效率。内核由直接相连的空穴传输型咔唑基团和电子亲和型芳香 1,2,4- 三唑基团组成。双极 FTzCz 是通过铃木偶联反应合成的,并具有良好的特性。由于其刚性和非平面化学结构,它不仅具有良好的热稳定性,而且还能同时促进空穴和电子的亲和性。将双极 FTzCz 与 PVK 混合可显著提高电磷光器件 [ITO|PEDOT:PSS|(PVK + FTzCz):Ir(ppy)3 (4 wt%)|BCP (10 nm)|Ca (50 nm)|Al (100 nm)]的性能。最大亮度和最大亮度效率分别从 3550 cd m-2 和 5.6 cd A-1 (纯 PVK 基器件)提高到 4510 cd m-2 和 9.9 cd A-1(PVK : FTzCz = 8 : 2 的混合器件)。我们的研究结果证明了双极 FTzCz 在提高电磷光器件性能方面的功效。