• Bulletin of the Korean Chemical Society
• /
• v.30 no.11
• /
• pp.2754-2758
• /
• 2009

Three novel phosphorescent 2-phenylpyridine-based iridium(III) complexes, $[(ppy)_2Ir(P\^{}N)]PF6\;(1),\;[(dfppy)_2Ir(P\^{}N)]PF_6$ (2), and $[(dfmppy)_2 Ir(P\^{}N)]PF6$ (3), where $P\^{}N$ = 2-[(diphenylphosphino)methyl]pyridine (dppmp), were synthesized and characterized. The absorption, photoluminescence, cyclic voltammetry and thermal stability of the complexes were investigated. The complexes showed bright blue luminescences at wavelengths of 448 $\sim$ 500 nm at room temperature in $CHCl_3$ and revealed that the $\pi$-acceptor ability of the phosphorous atom in the ancillary dppmp ligand plays an important role in tuning emission color resulting in a blue-shift emission. The single crystal structure of $[(dfmppy))_2Ir(P\^N)]PF_6$ was determined using X-ray crystallography. The iridium metal center adopts a distorted octahedral structure coordinated to two dfmppy and one dppmp ligand, showing cis C-C and trans N-N chelate dispositions. There is a $\pi-\pi$ overlap between π electrons delocalized in the difluorophenyl rings.

• Bulletin of the Korean Chemical Society
• /
• v.34 no.1
• /
• pp.167-173
• /
• 2013

A series of highly efficient red phosphorescent heteroleptic iridium(III) complexes 1-6 containing two cyclometalating 2-(2,4-substitued phenyl)quinoxaline ligands and one chromophoric ancillary ligand were synthesized: (pqx)$_2Ir$(mprz) (1), (dmpqx)$_2Ir$(mprz) (2), (dfpqx)$_2Ir$(mprz) (3), (pqx)$_2Ir$(prz) (4), (dmpqx)$_2Ir$(prz) (5), (dfpqx)$_2Ir$(prz) (6), where pqx = 2-phenylquinoxaline, dfpqx = 2-(2,4-diflourophenyl)quinoxaline, dmpqx = 2-(2,4-dimethoxyphenyl)quinoxaline, prz = 2-pyrazinecarboxylate and mprz = 5-methyl-2-pyrazinecarboxylate. The absorption, emission, electrochemical and thermal properties of the complexes were evaluated for potential applications to organic light-emitting diodes (OLEDs). The structure of complex 2 was also determined by single-crystal X-ray diffraction analysis. Complex 2 exhibited distorted octahedral geometry around the iridium metal ion, for which 2-(2,4-dimethoxyphenyl)quinoxaline N atoms and C atoms of orthometalated phenyl groups are located at the mutual trans and cis-positions, respectively. The emission spectra of the complexes are governed largely by the nature of the cyclometalating ligand, and the phosphorescent peak wavelengths can be tuned from 588 to 630 nm with high quantum efficiencies of 0.64 to 0.86. Cyclic voltammetry revealed irreversible metal-centered oxidation with potentials in the range of 1.16 to 1.89 V as well as two quasi-reversible reduction waves with potentials ranging from -0.94 to -1.54 V due to the sequential addition of two electrons to the more electron-accepting heterocyclic portion of two distinctive cyclometalated C^N ligands.

• Journal of Ceramic Processing Research
• /
• v.13 no.spc2
• /
• pp.328-331
• /
• 2012

With the recent development of super-precision optical instruments, camera modules for devices, such as portable terminals and digital camera lenses, are increasingly being used. Since an optical lens is usually produced by high-temperature compression molding methods using tungsten carbide (WC) alloy molding cores, it is necessary to develop and study technology for super-precision processing of molding cores and coatings for the core surface. In this study, Rhenium-Iridium (Re-Ir) thin films were deposited onto a WC molding core using a sputtering system. The Re-Ir thin films were prepared by a multi-target sputtering technique, using iridium, rhenium, and chromium as the sources. Argon and nitrogen were introduced through an inlet into the chamber to be the plasma and reactive gases. The Re-Ir thin films were prepared with targets having a composition ratio of 30 : 70, and the Re-Ir thin films were formed with a 240 nm thickness. Re-Ir thin films on WC molding core were analyzed by scanning electron microscope (SEM), atomic force microscope (AFM), and Ra (the arithmetical average surface roughness). Also, adhesion strength and coefficient friction of Re-Ir thin films were examined. The Re-Ir coating technique has received intensive attention in the coating processes field because of promising features, such as hardness, high elasticity, abrasion resistance and mechanical stability that result from the process. Re-Ir coating technique has also been applied widely in industrial and biomedical applications. In this study, WC molding core was manufactured, using high-performance precision machining and the effects of the Re-Ir coating on the surface roughness.

• Transactions on Electrical and Electronic Materials
• /
• v.12 no.2
• /
• pp.80-83
• /
• 2011

We have fabricated phosphorescent white organic light-emitting devices (WOLEDs) with a spin-coated poly(Nvinylcarbazole) [PVK] host layer. Iridium(III) bis[(4,6-difluorophenyl)-pyridinato-N,$C^{2'}$]picolinate (FIrpic), tris(2-phenylpyridine)iridium(III) [$Ir(ppy)_3$], and tris(2-phenyl-1-quinoline)iridium(III) [$Ir(phq)_3$], were used as the blue, green, and red guest materials, respectively. The PVK was mixed with FIrpic, $Ir(ppy)_3$, and $Ir(phq)_3$ molecules in a chlorobenzene solution and spin-coated in order to prepare the emission layer; 3-(4-biphenylyl)-4-phenyl-5-(4-tertbutylphenyl)-1,2,4-triazole (TAZ) was used as an electron transport material. The resultant device structure was ITO/PVK:FIrpic:$Ir(ppy)_3:Ir(phq)_3$/TAZ/LiF/Al. The electroluminescence, efficiency, and electrical conduction characteristics of the WOLEDs based on the doped PVK host layer were investigated. The maximum current efficiency of the three wavelength WOLED with the doped PVK host was 19.2 cd/A.

• 한국정보디스플레이학회:학술대회논문집
• /
• 2003.07a
• /
• pp.174-177
• /
• 2003

We report four new phosphorescent iridium(III} complexes with 2,4-diphenyl-1,3-oxazole [$Ir(24dpo)_3$], 2,5-diphenyl-1,3-oxazole [$Ir(25dpo)_3$], 2-(3-thienyl) pyridine [$Ir(3thpyh)_3$] and [Ir(3thpy)2(acac)]. Three of them demonstrate good photophysical properties to be used as dopants to organic polymer matrix or to be used "as is" without a host matrix to fabricate OLEDs. Green and yellow light emission was observed for the photoluminescence: 569/525, 549/498 nm and 557,604/533 (solid state/$CH_2Cl_2$ solution) for $Ir(24dpo)_3$, $Ir(3thpyh)_3$ and $Ir(3thpyh)_2$acac respectively. Room temperature luminescent lifetimes are 2.5 and 1.8 ${\mu}s$ and quantum efficiencies 37 and 53%for $Ir(24dpo)_3$ and $Ir(3thpyh)_3$. The complexes are stable in air and sublimable at low pressure without considerable decomposition. Comparison of physicochemical properties of the reported iridium(III) cyclometalated compounds with that known from literature is carried out.

• Proceedings of the Korean Society of Medical Physics Conference
• /
• 2005.04a
• /
• pp.42-46
• /
• 2005

The Dose calculation program for the Buchler remote after-loading system was developed. We use iridium source for the tandem and cessium for the ovoids. We determined the source length and distributions by dividing the program disk to 72 points. The dose rate for the each program disk were calculated and stored to the tables for the xy coordinates. The dose rate for the interesting points for the patients were calculated by using these tables. We also made isodose curve from the calculations. By using the program, we could calculate the dose rate for the various points of the patient quickly and accurately.

• Journal of Korean Society on Water Environment
• /
• v.33 no.1
• /
• pp.34-39
• /
• 2017

Under a corrosive environment, electrodes that are applied in the water-treatment system need not only very high electrochemical activity for fast reactions, but also high durability for cost saving. Therefore, the fabrication condition of iridium electrodes was examined to produce a more durable iridium electrode in this study. Tantalum was selected as a binder to enhance the durability of the iridium electrode. Investigation of the weight ratio between the catalyst and the binder to improve electrochemical activity was performed. Also, to compare the effect of the different coating amounts of the catalyst, the results of CV (Cyclic Voltammetry) and EIS (Electrochemical Impedance Spectroscopy) were discussed. Furthermore, an ALT(Accelerated Lifetime Test) was designed and applied to the electrodes to determine the conditions for highly durable electrode fabrication.

• Journal of Electrochemical Science and Technology
• /
• v.8 no.2
• /
• pp.96-100
• /
• 2017

Iridium(III) bis(2-phenylpyridinato-$N,C^{2^{\prime}}$)acetylacetonate ($(ppy)_2Ir(acac)$), a green dopant used in organic light-emitting devices (OLEDs), was subjected to electrochemical characterization to estimate its formal oxidation potential ($E^{o^{\prime}}$), HOMO energy level ($E_{HOMO}$), electron transfer rate constant ($k^{o^{\prime}}$), and diffusion coefficient ($D_o$). The employed combination of voltammetric methods, i.e., cyclic voltammetry (CV), chronocoulometry (CC), and the Nicholson method, provided meaningful insights into the electron transfer kinetics of $(ppy)_2Ir(acac)$, allowing the determination of $k^{o^{\prime}}$ and $D_o$. The quasi-reversible oxidation of $(ppy)_2Ir(acac)$ furnished information on $E^{o^{\prime}}$ and $E_{HOMO}$, allowing the latter parameter to be easily estimated by electrochemical methods without relying on expensive and complex ultraviolet photoemission spectroscopic (UPS) measurements.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.24 no.3
• /
• pp.219-223
• /
• 2011

Rhenium-Iridium(Re-Ir) thin films were deposited onto the tungsten carbide(WC) molding core by sputtering system. The Re-Ir films were prepared by multi-target sputtering with iridium, rhenium and chromium as the sources. Argon and nitrogen were inlet into the chamber to be the plasma and reactive gases. The Re-Ir thin films were prepared with targets having atomic percent of 3:7 and the Re-Ir thin films were formed with 240 nm thickness. The Re-Ir thin films on tungsten carbide molding core were analyzed by scanning electron microscope(SEM) and surface roughness. Also, adhesion strength and coefficient friction of Re-Ir thin film were examined. The Re-Ir coating technique has been intensive efforts in the field of coating process because the coating technique and process have been their feature, like hardness, high elasticity, abrasion resistance and mechanical stability and also have been applied widely the industrial and biomedical areas. In this report, tungsten carbide(WC) molding core was manufactures using high performance precision machining and the efforts of Re-Ir coating on the surface roughness.

• Bulletin of the Korean Chemical Society
• /
• v.15 no.11
• /
• pp.980-984
• /
• 1994

Monomeric rhodium and iridium diimine complexes $Cp^*M(HNRNH)(Cp^*$ = 1,2,3,4,5-pentamethylcyclopentadienyl : (M=lr; R=o-$C_6H_4 (1a), 4,5-(CH_3)_2-C_6H_2-1,2 (1b), 4,5-(Cl)_2-C_6H_2-1,2$ (1c), NCC=CCN-1,2 (1d): M=Rh; R=NCC=CCN-1,2 (1e)) have been synthesized from $[CP^*MCl_2]_2$ and 2 equiv. of diamine in the presence of $NEt_3$. The Crystal structure of 1a was determined by X-ray diffraction method : 1a was crystallized in the monoclinic system, space group $P2_{1/c}$, with lattice constants a=9.543 (1) ${\AA}$, b=16.286 (1) ${\AA}$, c=10.068 (1) ${\AA}$ and ${\beta}$=99.25 (1), with Z= 4. Least-squares refinement of the structure led to R factor of 0.049. The coordination sphere of rhodium and iridium can be described as a 2-legged piano-stool. All complexes are highly colored. Electrochemical studies show that 1d and 1e display quasi-reversible reduction and 1a-1c display irreversible reductions, suggesting that the acceptor orbital might be localized on the diimine ring.