Highly Phosphorescence Iridium Complexes and Their Application in Organic Light-Emitting Devices

Abstract

A new series of iridium(III) mixed ligand complexes TBA[Ir(ppy)(2)(CN)(2)] (1), TBA[Ir(ppy)(2)(NCS)(2)] (2), TBA[Ir(ppy)(2)(NCO)(2)] (3), and [Ir(ppy)(2)(acac)] (4) (ppy = 2-phenylpyridine; acac = acetoylacetonate, TBA = tetrabutylammonium cation) have been developed and fully characterized by UV-vis, emission, IR, NMR, and cyclic voltammetric studies. The lowest energy MLCT transitions are tuned from 463 to 494 nm by tuning the energy of the HOMO levels. These complexes show emission maxima in the blue, green, and yellow region of the visible spectrum and exhibit unprecedented phosphorescence quantum yields, 97 +/- 3% with an excited-state lifetimes of 1-3 micros in dichloromethane solution at 298 K. The near-unity quantum yields of these complexes are related to an increased energy gap between the triplet emitting state and the deactivating e(g) level that have been achieved by meticulous selection of ligands having strong ligand field strength. Organic light-emitting devices were fabricated using the complex 4 doped into a purified 4,4'-bis(carbazol-9-yl)biphenyl host exhibiting a maximum of the external quantum efficiencies of 13.2% and a power efficiency of 37 lm/W for the 9 mol % doped system.

Exploring energy transfer in luminescent heterometallic ruthenium–iridium ion pairs

“…TBA[Ir(ppy) 2 (CN) 2 ] (TBA [1]), 1 and [Ru(dtbubpy) 3 ]Cl 2 , ( [2]Cl 2 ), 2 were synthesized according to previously reported procedures, and the spectroscopic and MS data matched those found in the literature. 1 H NMR spectra were recorded on a Bruker Avance spectrometer at 400 MHz, the chemical shifts are referred to the residual peak of the solvent. The following abbreviations have been used for multiplicity assignments: "s" for singlet, "d" for doublet, "t" for triplet, "m" for multiplet.…”

Electroluminescence characteristics of n-type matrix materials doped with iridium-based green and red phosphorescent emitters

“…15͒ were obtained from the n-type matrix TAZ ͓doped with 12% bis͑2-phenylpyridine͒ iridium͑III͒ acetylacetonate͔ and the combination of the p-type matrix 4 , 4Ј ,4Љ-tris͑N-carbazolyl͒-triphenylamine and n-type matrix TAZ ͑doped with fac-tris͑2-phenylpyridine͒ iridium͑III͒ ͓8%Ir͑ppy͒ 3 ͔͒, respectively, whereas about 13% EQE was obtained from the p-type matrix CBP. 2,3,16,17 For red phosphorescent OLEDs with iridium-based emitters, there were several reports that evaluate both p-type and n-type matrices. [12][13][14] The devices with p-type matrix such as CBP ͑when doped with 7% bis͑2-͑2Ј-benzo͓4 5-a͔ thienyl͒pyridinato-N , C 3 Ј͒iridium ͑acetyl-acetonate͒ ͓btp 2 Ir͑acac͔͒͒ and 4 , 4Ј-bis͓N-͑1-naphthyl͒-N-phenylamino͔biphenyl ͓␣-NPD, when doped with 20% tris͑1-phenyliso-quinoline͒iridium͑III͔͒ were found to exhibit a bit higher performance than those with n-type matrix such as TPBi and BAlq.…”

Red-Orange Emissive Cyclometalated Neutral Iridium(III) Complexes and Hydridoiridium(III) Complex Based on 2-Phenylquinoxaline : Structure, Photophysics and Reactivity of Acetylacetone Towards Cyclometalated Iridium Dimer

“…Therefore, the respective emission data led to the conclusion that the saturated red emission can be achieved using cyclometalated ligands containing electron-donating substituent at the phenyl group, direct nitrogen substitution for carbon at the p framework 19 and extended p conjugation. For example, complex 1, (pqx) 2 Ir(acac) (λ PL,max = 583 nm) showed a red shift compared to (ppy) 2 Ir(acac) 20 (λ PL,max = 516 nm). Electrochemical Studies.…”