Dendritic Ir(iii) complexes functionalized with triphenylsilylphenyl groups: Synthesis, DFT calculation and comprehensive structure-property correlation
作者:Jae Jin Kim、Youngmin You、Young-Seo Park、Jang-Joo Kim、Soo Young Park
DOI:10.1039/b913122a
日期:——
We report on the synthesis, DFT calculations and structure-property relationships of phosphorescent Ir(III) complexes with varied number and position of triphenylsilylphenyl substituents. The attachment of the dendritic triphenylsilylphenyl group at the pyridine part of the phenylpyridine ligand induced a stronger metal-to-ligand charge-transfer (MLCT) transition and lower band-gap energy than did the unfunctionalized complex, Ir(ppy)3. On the other hand, the attachment of the triphenylsilylphenyl group at the phenyl part of the phenylpyridine ligand induced a stronger ligand-centered (LC) transition. It was specifically found that the excited state intermolecular interactions, which give rise to non-radiative decay, were more efficiently suppressed when the triphenylsilylphenyl group was attached at the pyridine part of the phenylpyridine ligand and also when the number of substituents was increased. Such site-isolation effects and improved solubility due to the triphenylsilylphenyl group encapsulation made it possible to fabricate wet-processed polymer light-emitting devices from these functionalized Ir(III) complexes. Both the doped poly(vinylcarbazole) (PVK) films and the neat films of our triphenylsilylphenyl based dendritic Ir(III) complexes afforded moderate to high electrophosphorescence efficiencies with excellent phase homogeneity (4.1%/1.7% for Ir(TPSppy)3, 5.9%/2.5% for Ir(ppyTPS)3 and 1.8%/1.8% for Ir(TPSppyTPS)3 (doped polymer film/neat film, respectively)). Moreover, it is noteworthy that the triphenylsilylphenyl substituents greatly enhanced the thermal stability of the dendritic Ir(III) complexes.
我们报告了具有不同数量和位置的三苯基硅基取代基的磷光铱(III)配合物的合成、DFT 计算和结构-性质关系。与未官能化的络合物 Ir(ppy)3 相比,在苯基吡啶配体的吡啶部分附着树枝状三苯基硅基会诱导更强的金属-配体电荷转移(MLCT)转变和更低的带隙能。另一方面,在苯基吡啶配体的苯基部分连接三苯基硅基会诱发更强的配体中心转变(LC)。研究特别发现,当三苯基甲酰基附着在苯基吡啶配体的吡啶部分时,以及当取代基的数量增加时,会更有效地抑制激发态分子间相互作用,这种相互作用会导致非辐射衰变。这种位点隔离效应以及三苯基硅烷基团封装带来的溶解性改善,使得利用这些功能化 Ir(III) 复合物制造湿法聚合物发光器件成为可能。掺杂聚(乙烯基咔唑)(PVK) 薄膜和三苯基硅酰基树枝状 Ir(III)复合物的纯薄膜都具有中等到较高的电致磷光效率和出色的相均匀性(Ir(TPSppy)3 为 4.1%/1.7%,Ir(ppyTPS)3 为 5.9%/2.5%,Ir(TPSppyTPS)3 为 1.8%/1.8%(掺杂聚合物薄膜/纯薄膜))。此外,值得注意的是,三苯基硅基苯基取代基大大提高了树枝状 Ir(III) 复合物的热稳定性。