Benzimidazole–carbazole-based bipolar hosts for high efficiency blue and white electrophosphorescence applications
作者:Hong Huang、Xiao Yang、Biao Pan、Lei Wang、Jiangshan Chen、Dongge Ma、Chuluo Yang
DOI:10.1039/c2jm31765f
日期:——
A series of novel bipolar blue phosphorescent host materials mBICP, mBINCP and mBIPhCP have been designed and synthesized, which comprehensively outperform the widely used phosphorescent host, 1,3-di(9H-carbazol-9-yl)benzene (mCP). The thermal, photophysical and electrochemical properties of these host materials were finely tuned through linking different carbazole moieties to the benzimidazole. mBICP (Tg = 84 °C) and mBIPhCP (Tg = 103 °C) exhibit high morphological stabilities in comparison with mCP. Theoretical calculations show that the HOMO/LUMO orbitals of these materials are mainly dispersed on the electron donating and electron accepting groups, respectively. A blue PhOLED device fabricated using mBICP as the host exhibits a maximum external quantum efficiency (ηEQE,max) of 18.7% and a maximum power efficiency (ηP,max) of 33.6 lm Wâ1. Interestingly, the external quantum efficiencies (ηEQE) are still as high as 17.1% at a high luminance of 1000 cd mâ2. Furthermore, the two-color, all-phosphor and single-emitting-layer white device hosted by mBICP achieved a maximum external quantum efficiency (ηEQE,max) of 20.5% corresponding to a maximum power efficiency (ηP,max) of 53.3 lm Wâ1.
设计合成了一系列新型双极蓝色磷光主体材料mBICP、mBINCP和mBIPhCP,其综合性能优于广泛使用的磷光主体1,3-二(9H-咔唑-9-基)苯(mCP)。通过将不同的咔唑部分与苯并咪唑连接,可以对这些主体材料的热、光物理和电化学性能进行微调。与mCP相比,mBICP(Tg=84℃)和mBIPhCP(Tg=103℃)表现出较高的形态稳定性。理论计算表明,这些材料的HOMO/LUMO轨道主要分别分散在给电子基团和受电子基团上。使用 mBICP 作为主体制造的蓝色 PhOLED 器件的最大外量子效率 (ΔEQE,max) 为 18.7%,最大功率效率 (ΔP,max) 为 33.6 lm W-1。有趣的是,在1000 cd m±2的高亮度下,外量子效率(ΔEQE)仍然高达17.1%。此外,mBICP主导的双色、全荧光粉和单发射层白光器件实现了20.5%的最大外量子效率(ΔEQE,max),对应于最大功率效率(ΔP,max) 53.3 lm W-1。