Synthesis of new iridium complexes and their electrophosphorescent properties in polymer light-emitting diodes
作者:Weiguo Zhu、Chuanzhen Liu、Lijun Su、Wei Yang、Ming Yuan、Yong Cao
DOI:10.1039/b205310a
日期:2003.12.10
Several new iridium complexes with p-substituted 2-phenylpyridine (R-PPy) ligands have been synthesized and characterized. The complexes were incorporated into phosphorescent polymer light-emitting devices using soluble poly[1,4-bis(6′-cyano-6′-methylheptyloxy)phenylene] (CNPPP) as the host and the resultant materials compared with Ir(PPy)3-doped devices. Green electrophosphorescence was observed, with peak emission at about 495 and 515 nm. Among the devices fabricated, highly efficient polymer light-emitting diodes were obtained with CNPPP doped with fac-tris[2-(4-tert-butylphenyl)pyridinato]iridium. An external quantum efficiency of 4.4% (photoluminescence/electroluminescence) and a luminous efficiency of 10 cd A−1 were obtained at 120 cd m−2. These values remain at 4.2% and 10 cd A−1, respectively, at 2500 cd m−2. The improvement is attributed to improved interaction between the guest and host, and to better and more complete energy transfer from the host singlet to the guest triplet state. These results demonstrate that efficient electrophosphorescence is not limited to small molecule organic light-emitting diodes, it can also be achieved in devices made with polymer hosts.
几种带有对位取代的 2-苯基吡啶 (R-PPy) 配体的新型铱配合物已被合成并表征。以可溶性聚[1,4-双(6'-氰基-6'-甲基庚氧基)亚苯基](CNPPP)为主体,将配合物引入磷光聚合物发光器件中,并将所得材料与Ir(PPy)3进行比较-掺杂器件。观察到绿色电致磷光,峰值发射位于约 495 和 515 nm 处。在所制造的器件中,利用掺杂fac-三[2-(4-叔丁基苯基)吡啶]铱的CNPPP获得了高效聚合物发光二极管。在120 cd m−2 下获得了4.4% 的外量子效率(光致发光/电致发光)和10 cd A−1 的发光效率。在 2500 cd m−2 时,这些值分别保持在 4.2% 和 10 cd A−1。这种改进归因于客体和主体之间相互作用的改善,以及从主体单线态到客体三线态更好、更完整的能量转移。这些结果表明,高效的电致磷光不仅限于小分子有机发光二极管,它也可以在由聚合物主体制成的器件中实现。