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Efficient blue-, green-, and red-light-emitting organic diodes are fabricated using binuclear platinum complexes as phosphorescent dopants. The series of complexes used here have pyrazolate bridging ligands and the general formula C^NPt(μ-pz) 2 PtC^N (where C^N = 2-(4',6'-difluorophenyl)pyridinato-N,C 2' , pz = pyrazole (1), 3-methyl-5-tert-butylpyrazole (2), and 3,5-bis(tert-bu-tyl)pyrazole (3)). The Pt-Pt distance in the complexes, which decreases in the order 1>2>3, solely determines the electroluminescence color of the organic light-emitting diodes (OLEDs). Blue OLEDs fabricated using 8 % 1 doped into a 3,5-bis(N-carbazolyl)benzene (mCP) host have a quantum efficiency of 4.3 % at 120 Cd m -2 , a brightness of 3900 Cd m -2 at 12 V, and Commission Internationale de L'Eclairage (CIE) coordinates of (0.11, 0.24). Green and red OLEDs fabricated with 2 and 3, respectively. also give high quantum efficiencies (-6.7%), with CIE coordinates of (0.31, 0.63) and (0.59, 0.46), respectively. The current-density-voltage characteristics of devices made using dopants 2 and 3 indicate that hole trapping is enhanced by short Pt-Pt distances (< 3.1 A). Blue electrophosphorescence is achieved by taking advantage of the binuclear molecular geometry in order to suppress dopant intermolecular interactions. No evidence of low-energy emission from aggregate states is observed in OLEDs made with 50 % 1 doped into mCP. OLEDs made using 100 % 1 as an emissive layer display red luminescence, which is believed to originate from distorted complexes with compressed Pt-Pt separations located in defect sites within the neat film. White OLEDs are fabricated using 1 and 3 in three different device architectures, either with one or two dopants in dual emissive layers or both dopants in a single emissive layer. All the white OLEDs have high quantum efficiency (∼5 %) and brightness (∼600 Cd m -2 at 10 V).

The synthesis of hole transport, electron transport, and functionalized β-diketone monomers, as well as their living radical polymerization, is described. Utilizing a second-generation nitroxide in...

Several new iridium based cyclometalated complexes were investigated as phosphorescent dopants for molecularly doped polymeric organic light-emitting diodes. Specifically, the complexes used in this study were iridium (III) bis(2-phenylpyridinato-N,C2′) (acetylacetonate) [ppy], iridium (III) bis(7,8-benzoquinolinato-N,C3′) (acetylacetonate) [bzq], iridium (III) bis(2-phenylbenzothiazolato-N,C2′) (acetylacetonate) [bt], iridium (III) bis(2-(2′-naphthyl)benzothiazolato-N,C2′) (acetylacetonate) [bsn] and iridium (III) bis(2-(2′-benzo[4,5-a]thienyl)pyridinato-N,C3′) (acetylacetonate) [btp]. Single layer devices of doped polyvinylcarbazole: 2-(4-biphenyl)-5-(4-tert-butylphenyl)-1,3,4-oxadiazole give maximum external quantum efficiencies that varied from 3.5% for the ppy dopant to 0.4% for the btp dopant. Several different device heterostructure architectures were explored, and the best quantum efficiency of the devices reached 4.2% for the heterostructures.

A series of new bis(indenyl) zirconium diaryloxides of general formula Ind2Zr(OL)2 (L = C6H5, 2; C6F5, 3; 2,6-Me2C6H3, 4; 2,4,6-Me3C6H2, 5; 4-tBuC6H4, 6) were synthesized by a metathesis reaction of Ind2ZrCl2 (1) with the appropriate thallium aryloxide salt, TlOL. The complexes 1–6 were characterized by 1H and 13C NMR techniques. They were also examined as catalysts for ethene and 1-hexene polymerization with methylalumoxane as co-catalyst, and a trend of the polymerization activity as a function of aryloxide ligands was observed. An interpretation of this trend, considering both the electronic and steric effects of the substituents on the aryloxide rings, was proposed. Copyright © 2001 John Wiley & Sons, Ltd.

SnO2 nanocrystalline thin films are deposited on Al2O3 and SiO2/Si(100) by chemical vapor deposition starting from diethylaminodimethylstannane (IV) [(CH3)2Sn(N(C2H5)2)2]. X-ray photoelectron spectra of the principal core levels for the surface of a SnO2 film on SiO2/Si(100) are presented.

We demonstrate efficient blue electrophosphorescence using exothermic energy transfer from a host consisting of N,N′-dicarbazolyl-3,5-benzene (mCP) to the phosphorescent iridium complex iridium(III)bis[(4,6-difluorophenyl)-pyridinato-N,C2′]picolinate (FIrpic). By examining the temperature dependence of the radiative lifetime and the photoluminescence of a film of mCP doped with FIrpic, we confirm the existence of exothermic energy transfer in contrast to the endothermic transfer characteristic of the N,N′-dicarbazolyl-4-4′-biphenyl and FIrpic system. In employing exothermic energy transfer between mCP and FIrpic, a maximum external electroluminescent quantum efficiency of (7.5±0.8)% and a luminous power efficiency of (8.9±0.9)lm/W are obtained, representing a significant increase in performance over previous endothermic blue electrophosphorescent devices.

Cryogenic leak detection is critical to space missions, particularly for avoiding launch delays. The real-time, multi-location, early leak detection of oxygen and hydrogen down to ppm levels is extremely important for safety, reliability, and economic reasons. One of the significant challenges in meeting these requirements has been the drift effect that is caused by the exposure to extreme temperatures. This paper discusses the effect of the development of a sensor supporting matrix to improve the overall behavior of oxygen and hydrogen optical sensors at cryogenic temperatures. These achievements offer great advances in the fiber optic leak detection of cryogenic oxygen and hydrogen, specifically for space applications. Emphasis on operational conditions such as -150 K and vacuum environments, in addition to performance characteristics such as sensitivity (10 ppm) and response time (~ 3 sec), are addressed in this paper.

A series of cationic Ir(III) complexes with the general formula (C/N)2Ir(N/N)(+)PF6- featuring bis-cyclometalated 1-phenylpyrazolyl-N,C2' (C/N) and neutral diimine (N/N, e.g., 2,2'-bipyridyl) ligands were synthesized and their electrochemical, photophysical, and electroluminescent properties studied. Density functional theory calculations indicate that the highest occupied molecular orbital of the compounds is comprised of a mixture of Ir d and phenylpyrazolyl-based orbitals, while the lowest unoccupied molecular orbital has predominantly diimine character. The oxidation and reduction potentials of the complexes can be independently varied by systematic modification of either the C/N or N/N ligands with donor or acceptor substituents. The electrochemical redox gaps (E(ox)-E(red)) were adjusted to span a range between 2.39 and 3.08 V. All of the compounds have intense absorption bands in the UV region assigned to 1(pi-pi*) transitions and weaker charge-transfer (CT) transitions that extend to the visible region. The complexes display intense luminescence both in fluid solution and as neat solids at 298 K that is assigned to emission from a triplet metal-ligand-to-ligand CT (3MLLCT) excited state. The energy of the 3MLLCT state varies in nearly direct proportion to the size of the electrochemical redox gap, which leads to emission colors that vary from red to blue. Three of the (C/N)2Ir(N/N)(+)PF6- complexes were used as active materials in single-layer light-emitting electrochemical cells (LECs). Single-layer electroluminescent devices were fabricated by spin-coating the Ir complexes onto an ITO-PEDOT/PSS substrate followed by deposition of aluminum contacts onto the organic film. Devices were prepared that give blue, green, and red electroluminescence spectra (lambda(max) = 492, 542, and 635 nm, respectively), which are nearly identical with the photoluminescence spectra of thin films of the same materials. The single-layer LECs give peak external quantum efficiencies of 4.7, 6.9, and 7.4% for the blue, green, and red emissive devices, respectively.

A near-white light-emitting polymer, consisting of hole transport (HT), electron transport (ET), and phosphorescent Pt functionalities, was prepared and utilized as the emissive layer in solution-processed OLEDs. The air-stable devices had a maximum external quantum efficiency of 4.6%.

The title compound, di-μ-diethyl­amido-N:N-bis­[chloro­di­methyl­tin(IV)], consists of discrete [Sn2Cl2(CH3)4(C4H10N)2] dimer mol­ecules, with Sn atoms linked by bridging diethyl­amido groups. The coordination geometry about the metal atom is distorted trigonal bipyramidal, with the two methyl C atoms and one N atom in the equatorial plane, and the Cl and second N atom in axial positions.