The effects of the rigidity of molecular recognition sites in fluorene-based conjugated polymers P1 and P2 on metal ion sensing have been investigated. The structures of polymers P1 and P2 have twisted 2,2

A type of soluble and thermally stable ladder-type poly(p-phenylene) (LPF) with fluorene units in polymer backbone has been synthesized by Suzuki coupling and Friedel-Crafts ring-closing reaction. The full characterization of structures and properties as well as the performances of electroluminescence devices of the new ladder polymers are presented. LPFs show the well-defined structures, high molecular weights, excellent thermal stability, and good solubility in common organic solvents. The high-efficiency emission and absence of low-energy emission band in photoluminescence spectra are observed from LPFs both in the solution and in the solid film. Furthermore, the single layer light-emitting device using LPFs as the active layer shows very stable blue-green emission with maximum luminescence of 5400 cd/m2 and maximum luminance efficiency of 0.66 cd/A. The extraordinary low concentration of keto defects in LPFs may be corresponding to the improvement in optical and device properties. The attractive properties exhibited by new ladder-type poly(p-phenylene)s establish them as good candidates for active layers in light-emitting devices.

A series of

The novel biphenyl derivative 1, which has planar conformation in crystal at room temperature, is synthesized and investigated by X-ray diffraction. A hydrogen-bonding network, which may be the driving force for the formation of planar conformation, is observed in the crystal of 1. 1 exhibits a strong UV-fluorescent emission in the solid state at room temperature.

Red electrophosphorescence from light-emitting devices based on a ruthenium(II) complex [Ru(4,7-Ph2-phen)3]2+-doped wide-band-gap semiconductive polymers, e.g., poly(vinylcarbazole) (PVK), polydihexylfluorene (PF), and ladder-like polyphenylene (LPPP), as the emitting layer are reported. These polymers show the short-wavelength electroluminescence emission peaking ranged from 410 to 490 nm, which overlaps well with the absorption band of [Ru(4,7-Ph2-phen)3]2+; however, very efficient energy transfer was investigated in the PVK system, likely due to relative long excited-state lifetimes of PVK than that of PF and LPPP and good chemical compatibility of [Ru(4,7-Ph2-phen)3]2+ with PVK. The EL spectra show the characteristic spectrum of [Ru(4,7-Ph2-phen)3]2+, with a peak at 612nm and CIE of (0.62, 0.37) which is comparable with standard red color. The optimized device ITO/PVK 5wt % [Ru(4,7-Ph2-phen)3]2+/PBD/Alq3/LiF/Al shows the maximum luminance efficiency and power efficiency of 8.6 cd/A and 2.1lm/W, respectively.

The utilization of molecular phosphorescent dyes in polymer-based organic light emitting diodes (OLEDs) was investigated by codoping several phosphorescent dopants into poly(N-vinylcarbazole) (PVK)-based single layer light emitting diodes (LEDs). In particular, green fac-tris(2-phenylpyridine)iridium(III), [Ir(ppy)3], red tris(4,7-diphenyl-1,10-phenanthroline)rhenium dications, [Ru(4,7-Ph2-phen)3]2+, and (2,3,7,8,12,13,17,18-octaethyl-21H,23H-porphyrin)platinum(II) (PtOEP) were used. In the phosphorescence dye doubly doped PVK system ca. x wt % [Ru(4,7-Ph2-phen)3]2+:1wt % Ir(ppy)3:PVK(x) 0.5-5), the intensity ratio (Ri) of red emission vs green emission as a function of doping ratio (Rc) of [Ru(4,7-Ph2-phen)3]2+ vs Ir(ppy)3 is found according to a power-law function with the exponent of 2.0 (0.2 for photoluminescence, which obey the power law with Ri

We demonstrate novel organic light-emitting diode (LED) materials that contain a green phosphorescent dye (dmbpy)Re(CO)3Cl (dmbpy 4,4'-dimethyl-2,2'-bipyridine), and a red fluorescent dye 4-dicyanomethylene-6-(p-dimethylaminostyryl)-2-methyl-4H-pyran (DCM) as dopants and polyvinylcarbazole (PVK) as the host. The photoluminescence (PL) and electroluminescence (EL) properties of these complex materials were studied. The energy transfer efficiency from PVK host to DCM is increased by the (dmbpy)Re(CO)3Cl co-dopant, which has an emission energy between that of PVK and DCM. The (dmbpy)Re(CO)3Cl, which emits a long-lived phosphorescence, is used as an energy coupler, providing the possibility to harvest both singlet and triplet energy in the devices. The pure red emission from DCM was observed from PL and EL spectra of (dmbpy)Re(CO)3-CI(>2.0 wt.-% ):DCM(>0.5 wt.%) doped PVK films, demonstrating an efficient energy transfer from PVK and (dmbpy)Re(CO)3-CI to DCM. By optimizing the concentration of DCM and (dmbpy)Re(CO)3Cl in PVK, a maximum EL quantum efficiency of 0.42 cd A 1 at a current density of 9.5 mA cm 2 was obtained. The EL quantum efficiency of the doubly doped device is significantly enhanced in comparison with both a DCM-only doped PVK device and a DCM-doped PVK device with the green fluorescent dye Alq3 as co-dopant. The improvement in the operating characteristics of the phosphorescent and fluorescent dye doubly doped device is attributed to efficient energy transler in the system, in which both triplet and singlet excitons are used for resultant emission in the polymer device.

The electroluminescence [EL] from a dinuclear-gold(I)-chlorate compound containing bridging phosphine ligands [Au2]dppm(Cl2) as emitting layer is reported. Devices with a structure Al/Au2(dppm)Cl2 /indium-tin-oxide demonstrated a uniform emission under the driving voltage below 1 V. The EL emission was from triplet excited state and the emission color of the device was found to depend on the deposition rate of Au2(dppm)Cl2, which can be explained as the different aggregation forms of the stacking compound in the deposition process.