Orange Phosphorescent Organic Light-emitting Diodes Using a Spirobenzofluorene-type Phospine Oxides as Host Materials
作者:Young-Min Jeon、In-Ho Lee、Chil-Won Lee、Jun-Yeob Lee、Myoung-Seon Gong
DOI:10.5012/bkcs.2010.31.10.2955
日期:2010.10.20
Spiro-type orange phosphorescent host materials, 9-diphenylphosphine oxide-spiro[fluorene-7,9'-benzofluorene] (OPH-1P) and 5-diphenylphosphine oxide-spiro[fluorene-7,9'-benzofluorene] (OPH-2P) were successfully prepared by a lithiation reaction followed by a phosphination reaction with diphenylphosphinic chloride. The EL characteristics of OPH-1P and OPH-2P as orange host materials doped with iridium(III) bis(2-phenylquinoline)acetylacetonate ($Ir(pq)_2acac$) were evaluated. The electroluminescence spectra of the ITO (150 nm)/DNTPD (60 nm)/NPB (30 nm)/OPH-1P or OPH-2P: $Ir(pq)_2acac$ (30 nm)/BCP (5 nm)/$Alq_3$ (20 nm)/LiF (1 nm)/Al (200 nm) devices show a narrow emission band with a full width at half maximum of 75 nm and $\lambda_max}$ = 596 nm. The device obtained from OPH-1P doped with 3% $Ir(pq)_2acac$ showed an orange color purity of (0.580, 0.385) and an efficiency of (14 cd/A at 7.0 V). The ability of the OPH-P series to combine a high triple energy with a low operating voltage is attributed to the inductive effect of the P=O moieties and subsequent energy lowering of the LUMO, resulting in the enhancement of both the electron injection and transport in the device. The overall result is a device with an EQE > 8% at high brightness, but operating voltage of less than 6.4 V, as compared to the literature voltages of ~10 V.
通过石化反应,再与二苯基膦酰氯发生磷化反应,成功制备了螺型橙色磷光宿主材料--9-二苯基氧化膦-螺[芴-7,9'-苯并呋喃](OPH-1P)和 5-二苯基氧化膦-螺[芴-7,9'-苯并呋喃](OPH-2P)。评估了 OPH-1P 和 OPH-2P 作为掺杂双(2-苯基喹啉)乙酰丙酮酸铱($Ir(pq)_2ac$)的橙色宿主材料的电致发光特性。评估了 ITO(150 nm)/DNTPD(60 nm)/NPB(30 nm)/OPH-1P 或 OPH-2P 的电致发光光谱:$Ir(pq)_2acac$(30 nm)/BCP(5 nm)/$Alq_3$(20 nm)/LiF(1 nm)/Al(200 nm)器件显示出一个窄发射带,半最大全宽为 75 nm,$\lambda_max}$ = 596 nm。由掺杂了 3% $Ir(pq)_2acac$ 的 OPH-1P 制成的器件显示出 (0.580, 0.385) 的橙色纯度和 (7.0 V 时 14 cd/A) 的效率。OPH-P 系列之所以能够将高三倍能量与低工作电压结合起来,是因为 P=O 分子的感应效应以及 LUMO 的能量随之降低,从而增强了器件中的电子注入和传输。总体结果是,该器件在高亮度下的 EQE > 8%,但工作电压低于 6.4 V,而文献中的电压约为 10 V。