Zhang Hongyang, Wang Haitao, Tanner Kevin, Schlachter Adrien, Chen Zhao, Harvey Pierre D, Chen Shuming, Wong Wai-Yeung
Department of Applied Biology and Chemical Technology, The Hong Kong Polytechnic University (PolyU), Hong Kong, China.
Department of Chemistry, Hong Kong Baptist University, Waterloo Road, Hong Kong, China.
Dalton Trans. 2021 Aug 4;50(30):10629-10639. doi: 10.1039/d1dt01557e.
A series of heteroleptic Ir(iii) complexes composed of two cyclometalated C^N ligands and one dipyrrinato ligand used as an ancillary ligand are synthesized and characterized. With the introduction of a fluorine atom, phenyl ring or diphenylamino group into both C^N ligands and by keeping the ancillary ligand unchanged, these Ir(iii) dipyrrinato phosphors do not show an obvious shift in their emission bands. They exhibit emissions extending well into the near-infrared region with an intense band located at around 685 nm in both photo- and electroluminescence spectra, and the deep red to near-infrared organic light emitting diodes (OLEDs) based on them afforded a maximum external quantum efficiency of 2.8%. Density functional theory (DFT) calculations show that both the electronic contributions on the lowest unoccupied molecular orbitals (LUMOs) and the highest energy semi-occupied molecular orbitals (HSOMOs) are mainly localized on the dipyrrinato ligand, indicating that the ancillary ligand, which remains unchanged in this series, exhibits a lower triplet state energy in the iridium phosphors than those involving the C^N ligands. Therefore a switch from "(C^N)2Ir" to dipyrrinato ligand-based emission is observed in these iridium(iii) complexes.
合成并表征了一系列由两个环金属化C^N配体和一个用作辅助配体的二吡咯啉基配体组成的杂配Ir(III)配合物。通过在两个C^N配体中引入氟原子、苯环或二苯胺基，并保持辅助配体不变，这些Ir(III)二吡咯啉基磷光体的发射带没有明显位移。它们在光致发光和电致发光光谱中均表现出延伸至近红外区域的发射，在685 nm左右有一个强发射带，基于它们的深红色至近红外有机发光二极管（OLED）的最大外量子效率为2.8%。密度泛函理论（DFT）计算表明，最低未占据分子轨道（LUMO）和最高能量半占据分子轨道（HSOMO）上的电子贡献主要定域在二吡咯啉基配体上，这表明在该系列中保持不变的辅助配体在铱磷光体中的三重态能量低于涉及C^N配体的那些。因此，在这些铱(III)配合物中观察到了从“(C^N)2Ir”到基于二吡咯啉基配体发射的转变。
