Solution-processible multi-component cyclometalated iridium phosphors for high-efficiency orange-emitting OLEDs and their potential use as white light sources
Solution-processible multi-component cyclometalated iridium phosphors for high-efficiency orange-emitting OLEDs and their potential use as white light sources
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DOI：
10.1002/adfm.200601205
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发表时间：
2007-10-15
影响因子：
19
通讯作者：
Wang, Lixiang
中科院分区：
文献类型：
--
作者：
Ho, Cheuk-Lam;Wong, Wai-Yeung;Wang, Lixiang
报道了由空穴转运咔唑和芴基2-苯基吡啶组成的几种多功能磷光环金属化铱配合物的合成和光物理研究。它们都是热稳定和形态稳定的非晶态固体。通过将电子推动咔唑单元结合到芴片段中来扩展π共轭，导致发射谱线的变色，增加了最高的占据分子轨道水平，并且由于咔唑单元倾向于促进空穴传输，从而改善了所产生的配合物中的电荷平衡。这些铱基三重态发射体在室温下发出强烈的橙色磷光，在溶液阶段的寿命相对较短。根据咔唑与芴的配位位置，研究了这些磷致咔唑芴功能化金属配合物的光致发光和电致发光性质。利用这些配合物作为溶液处理发射层的有机发光二极管（oled），即使不需要典型的空穴传输层，也显示出非常高的效率。这些橙色发射器件可以产生类似于30 cd a（-1）的最大电流效率，对应于类似于10% ph/el（每电子光子）的外部量子效率和类似于14 Im W-1的功率效率。同色铱荧光粉在器件性能上一般优于异色铱荧光粉。讨论了利用这些橙色荧光染料实现白色oled的潜力。
The synthesis and photophysical studies of several multifunctional phosphorescent iridium(III) cyclometalated complexes consisting of the hole-transporting carbazole and fluorene-based 2-phenylpyridine moieties are reported. All of them are isolated as thermally and morphological stable amorphous solids. Extension of the pi-conjugation through incorporation of electron- pushing carbazole units to the fluorene fragment leads to bathochromic shifts in the emission profile, increases the highest oc- cupied molecular orbital levels and improves the charge balance in the resulting complexes because of the propensity of the carbazole unit to facilitate hole transport. These iridium-based triplet emitters give a strong orange phosphorescence light at room temperature with relatively short lifetimes in the solution phase. The photo- and electroluminescence properties of these phosphorescent carbazolylfluorene-functionalized metalated complexes have been studied in terms of the coordinating position of carbazole to the fluorene unit. Organic light-emitting diodes (OLEDs) using these complexes as the solution-processed emissive layers have been fabricated which show very high efficiencies even without the need for the typical hole-transporting layer. I These orange-emitting devices can produce a maximum current efficiency of similar to 30 cd A(-1) corresponding to an external quantum efficiency of similar to 10 % ph/el (photons per electron) and a power efficiency of similar to 14 Im W-1. The homoleptic iridium phosphors generally outperform the heteroleptic counterparts in device performance. The potential of exploiting these orange phosphor dyes in the realization of white OLEDs is also discussed.