通过改变用于蓝色 PhOLED 的 9,9-二甲基芴基 Ir(III) 磷光掺杂剂中的杂环部分进行激发态调制,Journal of Materials Chemistry C

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通过改变用于蓝色 PhOLED 的 9,9-二甲基芴基 Ir(III) 磷光掺杂剂中的杂环部分进行激发态调制
Journal of Materials Chemistry C ( IF 5.7 ) Pub Date : 2022-02-03 , DOI: 10.1039/d1tc05559c
Bo-Sun Yun ₁ , So-Yoen Kim ₁ , Jin-Hyoung Kim ₁ , Sanghun Lee ₁ , Ho-Jin Son ₁ , Sang Ook Kang ₁

Affiliation

与 9,9-二甲基芴基的一系列 Ir( III ) 配合物（fac -Ir(py)、fac -Ir(pz)、fac -/ mer -Ir(im)和fac -/ mer -Ir(bzim) ） (dmf) 基配体 ( ^dmf C^N 或^dmf C^C:) 与各种杂环螯合部分（吡啶基 (py)、吡唑基 (pz)、咪唑基 (im) 和苯并咪唑基 (bzim)）进行了调整并进行了研究用于开发新型高效蓝色磷光掺杂剂。在这些 Ir( III ) 配合物中，mer -Ir(im)配合物与之前报道的 Ir(III )配合物，即mer-三( N-苯基-N′-甲基咪唑)铱( mer -Ir(pim) )、mer-三( N-二苯并呋喃苯基-N′-甲基咪唑)铱(mer - Ir ( im- O) )、 mer-三( N-二苯并噻吩-N'-甲基咪唑)铱( mer -Ir(im-S) )，以及用dmf部分取代苯基咪唑配体的苯基的效果也进行了研究。稳态光物理分析证实，观察到的发射颜色可从λ _em = 545 nm ( fac -Ir(py) ) 到λ _em = 462 nm ( fac -Ir(bzim) )，具体取决于杂环类型。此外，当苯基部分扩展到苯基咪唑配体的 dmf 类似物时，观察到较低的吸收和发射能量。通过 DFT/TD-DFT 计算和电化学分析，我们发现³ MLCT/ ³ LC 混合物基发射过程中 MLCT 贡献的相对程度以及激发态和基态之间的结构畸变（Δ Q _e）影响量子Ir( III的效率和辐射速率常数) 配合物，这与电致发光性能有关。在薄膜状态下具有≥85% 的高发射量子产率的mer -Ir(im)和fac -/ mer -Ir(bzim)被评估为蓝色 PhOLED 中的掺杂剂材料。mer -Ir (im) - 或fac -/ mer -Ir(bzim)掺杂的器件表现出 17.3%、14.2% 和 11.9% 的外部量子效率，CIE 坐标为 (0.21, 0.41), (0.18, 0.33) , 和 (0.19, 0.36)，分别。

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Excited-state modulation via alteration of the heterocyclic moiety in 9,9-dimethylfluorene-based Ir(III) phosphorescent dopants for blue PhOLEDs

A series of Ir(III) complexes (fac-Ir(py), fac-Ir(pz), fac-/mer-Ir(im), and fac-/mer-Ir(bzim)) with 9,9-dimethylfluorenyl (dmf)-based ligands (^dmfC^N or ^dmfC^C:) tuned with various heterocyclic chelating moieties (pyridyl (py), pyrazolyl (pz), imidazolyl (im), and benzimidazolyl (bzim)) were prepared and investigated for the development of novel efficient blue phosphorescent dopants. Of these Ir(III) complexes, the mer-Ir(im) complex was compared with the previously reported Ir(III) complexes, i.e., mer-tris(N-phenyl-N′-methylimidazole)iridium (mer-Ir(pim)), mer-tris(N-dibenzofuranylphenyl-N′-methylimidazole)iridium (mer-Ir(im-O)), and mer-tris(N-dibenzothiophenyl-N′-methylimidazole)iridium (mer-Ir(im-S)), and the effect of replacing the phenyl group of the phenylimidazole ligand with a dmf moiety was also investigated. The steady-state photophysical analysis confirmed that the observed emission colors were tunable from λ_em = 545 nm (fac-Ir(py)) to λ_em = 462 nm (fac-Ir(bzim)) depending on the heterocycle type. In addition, lower absorption and emission energies were observed when the phenyl moiety was extended to the dmf analogues of the phenylimidazole ligand. From DFT/TD-DFT calculations and electrochemical analysis, we found that the relative degree of MLCT contribution in the ³MLCT/³LC admixture-based emission process and the structural distortion (ΔQ_e) between the excited and ground states affect the quantum efficiencies and radiative rate constants of the Ir(III) complexes, which is related to the electroluminescence performance. The mer-Ir(im) and fac-/mer-Ir(bzim) with high emission quantum yields of ≥85% in the film state were evaluated as dopant materials in blue PhOLEDs. The mer-Ir(im)- or fac-/mer-Ir(bzim)-doped devices exhibited external quantum efficiencies of 17.3%, 14.2%, and 11.9% with CIE coordinates of (0.21, 0.41), (0.18, 0.33), and (0.19, 0.36), respectively.

更新日期：2022-02-03

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