Department of Chemical Engineering , National Tsing-Hua University , Hsinchu 30013 , Taiwan.
ACS Appl Mater Interfaces. 2019 Dec 11;11(49):45939-45948. doi: 10.1021/acsami.9b14168. Epub 2019 Dec 2.
Two pyridine-containing bipolar host materials with high triplet energy, 9,10-dihydro-9,9-dimethyl-10-(3-(6-(3-(9,9-dimethylacridin-10(9)-yl)phenyl)pyridin-2-yl)phenyl acridin (DDMACPy) and -(3-(6-(3-(diphenyl amino)phenyl)pyridin-2-yl)phenyl)--phenylbenzenamine (DTPAPy), are synthesized from the modification of the commonly adapted host material 2,6-bis(3-(9-carbazol-9-yl)phenyl)pyridine (DCzPPy). The highest occupied molecular orbital levels of DDMACPy (5.50 eV) and DTPAPy (5.60 eV) are found to be shallower than that of DCzPPy (5.90 eV) that leads to the improvement in hole injection from the hole transport layer PEDOT:PSS (WF = 5.10 eV). These host materials are used in the emitting layer of bluish-green organic light-emitting diode (OLED) with the thermally activated delayed fluorescence (TADF) emitter, 9,9-dimethyl-9,10-dihydroacridine-2,4,6-triphenyl-1,3,5-triazine, as the guest. The DDMACPy-based device shows the highest performance among them, with the maximum external quantum efficiency (EQE), current efficiency (CE), and power efficiency (PE) of 21.0%, 53.1 cd A, and 44.0 lm W at CIE (0.17, 0.42), respectively. By further doping with the red-emitting phosphor iridium(III) bis(2-phenylquinoline)(2,2,6,6-tetramethylheptane-3,5-ionate) [Ir(dpm)PQ] and yellow-emitting phosphor iridium(III) bis(4-(4--butylphenyl)thieno[3,2-]pyridinato-N,C20)acetylacetonate (PO-01-TB) emitters into the bluish-green emitting layer, a TADF-phosphor hybrid white OLED (T-P WOLED) is obtained with excellent EQE, CE, and PE of 17.4%, 48.7 cd A, and 44.5 lm W at CIE (0.35, 0.44), respectively. Moreover, both the bluish-green and WOLED show a low efficiency roll-off with external quantum efficiencies at the brightness of 1000 cd m (EQE) of 18.7 and 16.2%, respectively, which are the highest performance records among the solution-processed TADF bluish-green and T-P WOLEDs.
两种含吡啶的双极主体材料具有较高的三重态能量，9,10-二氢-9,9-二甲基-10-(3-(6-(3-(9,9-二甲基吖啶-10(9)-基)苯基)吡啶-2-基)苯基吖啶（DDMACPy）和-(3-(6-(3-(二苯基氨基)苯基)吡啶-2-基)苯基)--苯基苯甲胺（DTPAPy）是通过对常用主体材料 2,6-双(3-(9-咔唑-9-基)苯基)吡啶（DCzPPy）进行修饰合成的。DDMACPy（5.50 eV）和 DTPAPy（5.60 eV）的最高占据分子轨道能级被发现比 DCzPPy（5.90 eV）更浅，这导致空穴从空穴传输层 PEDOT:PSS（WF = 5.10 eV）中注入的改善。这些主体材料用于发射层的蓝绿光有机发光二极管（OLED）中，热活化延迟荧光（TADF）发射体为 9,9-二甲基-9,10-二氢吖啶-2,4,6-三苯基-1,3,5-三嗪。基于 DDMACPy 的器件在其中表现出最高的性能，在 CIE（0.17,0.42）处具有 21.0%的最大外量子效率（EQE）、53.1 cd A 的电流效率（CE）和 44.0 lm W 的功率效率（PE）。通过进一步掺杂红色发光磷光体铱（III）双（2-苯基喹啉）（2,2,6,6-四甲基庚烷-3,5-二酮）[Ir（dpm）PQ]和黄色发光磷光体铱（III）双（4-(4--丁基苯基)噻吩[3,2-]吡啶并-N，C20）乙酰丙酮酸盐（PO-01-TB）发射体到蓝绿光发射层中，获得了 TADF-磷光体混合白光 OLED（T-P WOLED），具有优异的 EQE、CE 和 PE，在 CIE（0.35,0.44）处分别为 17.4%、48.7 cd A 和 44.5 lm W。此外，蓝绿光和 WOLED 的效率滚降都很低，在亮度为 1000 cd m 时的外量子效率（EQE）分别为 18.7%和 16.2%，这是溶液处理 TADF 蓝绿光和 T-P WOLED 中的最高性能记录。
