Department of Chemistry, National Taiwan University, Taipei, Taiwan.
Chem Asian J. 2012 Jan 2;7(1):133-42. doi: 10.1002/asia.201100467. Epub 2011 Oct 13.
In this study, we synthesized and characterized a series of spirobifluorene-based bipolar compounds (D2 ACN, DNPACN, DNTACN, and DCzACN) in which a dicyano-substituted biphenyl branch, linked orthogonally to a donor biphenyl branch bearing various diarylamines, acted as an acceptor unit allowing fine-tuning of the morphological stability, triplet energy, bipolar transport behavior, and the HOMO and LUMO energy levels. The promising physical properties of these new compounds, together with their ability to transport electrons and holes with balanced mobilities, made them suitable for use as host materials in highly efficient phosphorescent organic light-emitting diodes (PhOLEDs) with green iridium-based- or red osmium-based phosphors as the emitting layer (EML). We adopted a multilayer structure to efficiently confine holes and electrons within the EML, thus preventing exciton diffusion and improving device efficiency. The device incorporating D2 ACN doped with the red emitter [Os(bpftz)(2)(PPhMe(2))(2)] (bpftz=3-(trifluoromethyl)-5-(4-tert-butylpyridyl)-1,2,4-triazolate) gave a saturated red electrophosphorescence with CIE coordinates of (0.65, 0.35) and remarkably high efficiencies of 20.3 % (21 cd A(-1)) and 13.5 Lm W(-1) at a practical brightness of 1000 cd m(-2).
在这项研究中，我们合成并表征了一系列基于螺二芴的双极化合物（D2 ACN、DNPACN、DNTACN 和 DCzACN），其中一个二氰基取代的联苯支链，与一个带有各种二苯胺的供体联苯支链正交连接，作为一个受体单元，可以精细调整形态稳定性、三重态能量、双极输运行为以及 HOMO 和 LUMO 能级。这些新化合物具有有前途的物理性质，并且能够以平衡的迁移率传输电子和空穴，因此适合用作高效磷光有机发光二极管（PhOLED）的主体材料，其中绿色铱基或红色锇基磷光体作为发射层（EML）。我们采用多层结构有效地将空穴和电子限制在 EML 内，从而防止激子扩散并提高器件效率。包含红色发射体[Os(bpftz)(2)(PPhMe(2))(2)]（bpftz=3-（三氟甲基）-5-（4-叔丁基吡啶基）-1,2,4-三唑）的 D2 ACN 掺杂器件实现了饱和红色电磷光，CIE 坐标为（0.65, 0.35），在 1000 cd m(-2)的实际亮度下，效率高达 20.3 %（21 cd A(-1)）和 13.5 Lm W(-1)。
