Homoleptic Cyclometalated Iridium Complexes with Highly Efficient Red Phosphorescence and Application to Organic Light-Emitting Diode

Abstract

Phosphorescence studies of a series of facial homoleptic cyclometalated iridium(III) complexes have been carried out. The complexes studied have the general structure Ir(III)(C-N)(3), where (C-N) is a monoanionic cyclometalating ligand: 2-(5-methylthiophen-2-yl)pyridinato, 2-(thiophen-2-yl)-5-trifluoromethylpyridinato, 2,5-di(thiophen-2-yl)pyridinato, 2,5-di(5-methylthiophen-2-yl)pyridinato, 2-(benzo[b]thiophen-2-yl)pyridinato, 2-(9,9-dimethyl-9H-fluoren-2-yl)pyridinato, 1-phenylisoquinolinato, 1-(thiophen-2-yl)isoquinolinato, or 1-(9,9-dimethyl-9H-fluoren-2-yl)isoquinolinato. Luminescence properties of all the complexes at 298 K in toluene are as follows: quantum yields of phosphorescence Phi(p) = 0.08-0.29, emission peaks lambda(max) = 558-652 nm, and emission lifetimes tau = 0.74-4.7 micros. Bathochromic shifts of the Ir(thpy)(3) family [the complexes with 2-(thiophen-2-yl)pyridine derivatives] are observed by introducing appropriate substituents, e.g., methyl, trifluoromethyl, or thiophen-2-yl. However, Phi(p) of the red emissive complexes (lambda(max) > 600 nm) becomes small, caused by a significant decrease of the radiative rate constant, k(r). In contrast, the complexes with the 1-arylisoquinoline ligands are found to have marked red shifts of lambda(max) and very high Phi(p) (0.19-0.26). These complexes are found to possess dominantly (3)MLCT (metal-to-ligand charge transfer) excited states and have k(r) values approximately 1 order of magnitude larger than those of the Ir(thpy)(3) family. An organic light-emitting diode (OLED) device that uses Ir(1-phenylisoquinolinato)(3) as a phosphorescent dopant produces very high efficiency (external quantum efficiency eta(ex) = 10.3% and power efficiency 8.0 lm/W at 100 cd/m(2)) and pure-red emission with 1931 CIE (Commission Internationale de L'Eclairage) chromaticity coordinates (x = 0.68, y = 0.32).

Synthesis, Diastereomer Separation, and Optoelectronic and Structural Properties of Dinuclear Cyclometalated Iridium(III) Complexes with Bridging Diarylhydrazide Ligands

“…Well-resolved vibronic structures at this temperature may also be indicative of a high LC contribution to their excited states. 69 Within experimental error there is no significant variation in PL properties between the diastereomers for 15 and 16.…”

Synthesis of substituted isoquinolines utilizing palladium-catalyzed α-arylation of ketones

“…alpha arylation | heterocycle | isoquinoline-N-oxide | one-pot T he isoquinoline motif and its derivatives form the cores of numerous natural products (1,2), are the central components of a number of pharmaceutical agents (3)(4)(5), and can provide the scaffold for chiral ligands (6,7) and valuable organic materials (8). However, traditional isoquinoline syntheses such as the Bischler-Napieralski (9, 10), Pictet-Spengler (11,12), and Pomeranz-Fritsch reactions (13)(14)(15) all centre around the lynchpin of electrophilic aromatic substitution and are thus often limited to electron-rich carbocycles (Scheme 1A).…”

Heteroleptic Phosphorescent Iridium(III) Compound with Blue Emission for Potential Application to Organic Light-Emitting Diodes

“…This can be due to the rigidochromic effect. 9 The triplet energy of the compound was estimated to be 2.67 eV, using emission maximum at 77 K. This value is similar than that of the standard sky-blue emitter Firpic (E T = 2.7 eV). Indeed, due to the introduction of ancillary ligand, (dfpypy) 2 Ir(mppy) shows an remarkable red-shifted emission(more than 30nm) in the fluid and solid states compared to homoleptic iridium(III) counterpart.…”