Minggui Xie

Energy transfer process from polymer to rare earth complexes

Abstract The interaction between poly( N -vinylcarbazole) (PVK) and rare earth (RE) complexes, such as Eu(thenoytrifluoacetonato) 4 -(monopyridinium) (Eu(TTA) 4 Py). Eu(nitrate) 3 (monophenanthroline) (Eu(NO 3 ) 3 phen) and Tb(acetylacetonato) 3 (monophenanthroline) (Tb(AcA) 3 phen), was investigated in solution as well as in films using the photoluminescence (PL) spectrum. In chloroform solution, the fluorescent intensity of the Eu(NO 3 ) 3 phen was enhanced by PVK; however, the fluorescent intensity of the Tb complex was greatly quenched by PVK. Strongly characteristic emissions of Eu 3+ and Tb 3+ were observed in Eu and Tb complex-dispersed PVK films, respectively. The excitation spectra of Eu complex-dispersed PVK films and Tb complex-dispersed PVK film are very similar to that of the pure PVK film, indicating that effective energy transfer occurs from PVK to the RE complexes. Based on the above experimental results, three types of organic electroluminescence (EL) devices with structure of ITO/Eu(NO 3 ) 3 phen:PVK/OXD-7/Al, ITO/Eu(TTA) 4 Py:PVK/OXD-7/Al and ITO/ Tb(AcA) 3 phen:PVK/OXD-7/Al (ITO = indium-tin oxide) were fabricated. Bright red emission can be observed in the first and second devices while bright green light was emitted from the latter device.

Efficient blue emission from pyrazoline organic light emitting diodes

Abstract Two kinds of pyrazoline derivatives, 3-(4-chlorophenyl)-4,5-dihydro-1,5-diphenyl 1- H -Pyrazole, ( P 1 ) and 3-(4-methoxyphenyl)-4,5-dihydro-1,5-diphenyl 1- H -Pyrazole ( P 2 ) were synthesized. They showed efficient photoluminescence (PL) in both solid state and solution. The emission peak of P 1 was observed at 450 nm and that of P 2 was at 432 nm. Two types of organic electroluminescent devices (OELDs) using these materials as emitting layer were fabricated, one is a three-layered structure device fabricated by dry process and another is a single or double layer structure device fabricated by a wet technique. These materials were found to function as good blue light-emitting materials for OELDs. The device with a structure of ITO/TPD/ P 1 /Alq 3 /Mg:Ag showed a turn-on voltage of 3.5 V, while the device using P 2 instead of P 1 gave a turn-on voltage of 3 V, both of them give green light resulting from Alq 3 and the maximum light intensity was 5710 cd/m 2 under driving voltage of 8.5 V. The device of ITO/PVK+ P 1 /Alq 3 /Al emitted bright blue light resulting from P 1 . It exhibited a maximum luminance of 200 cd/m 2 at a driving voltage of 12 V, and the device of ITO/PVK+ P 2 /Al exhibited blue light of 200 cd/m 2 at a driving voltage of 11 V.

Red electroluminescence from a novel europium β-diketone complex with acylpyrazolone ligand

Abstract A novel poly-ligand europium β-diketone complex was prepared, which contains ligand of 1-phenyl-3-methyl-4(4-butylbenzoyl)-5-pyrazolone (HPMBBP). Its structure is Eu(TTA) 2 (PMBBP)Phen. We investigated its PL and EL properties. When it was used as emitting material, the new Eu-complex exhibited intense photoluminescence (PL) and electroluminescence (EL) at 613 nm in a fabricated three-layer electroluminescent device: ITO/TPD/Eu(TTA) 2 (PMBBP)Phen/Alq 3 /Mg:Ag. The maximum luminance of 16 cd/m 2 from the device was obtained at 12.5 V.

Novel light-emitting polymers derived from fluorene and maleimide

A series of novel soluble light-emitting polymers derived from fluorene and maleimide were synthesized by a palladium-catalyzed Suzuki coupling reaction. The resulting polymers were characterized by NMR, FT-IR, elemental analysis, DSC, TGA and GPC. These polymers show very strong yellow PL emission and good solubility in common organic solvents, such as CH2Cl2, CH3Cl, toluene and xylene. DSC and TGA studies reveal that the novel polymers possess excellent thermal stability with high glass transition temperatures (Tg) and onset decomposition temperatures (Td). Cyclic voltammetry measurements demonstrated that the polymers have high electron affinity and good hole and electron transporting properties. Light emitting diodes (LEDs) with the configuration ITO/PEDOT : PSS/polymer/Mg:Ag were fabricated. All the LEDs show low turn-on voltages and good electroluminescence properties with yellow emission.

Novel pyrazoline derivative used as light emitter in blue organic electroluminescent devices

w . x . A novel pyrazoline derivative, 3- 4-methoxyphenyl -5- 4- 1,1-dimethylethylphenyl -4,5-dihydro-1-phenyl 1-H-Pyrazole P was 3 designed and synthesized. Its structure was elucidated by IR, 1 H NMR, MS, UV and elementary analysis. It had hole-transporting ability, . good film-formation, and excellent PL property. The device with a structure of ITOrPVKrP rAl could emit blue light 451 nm and the 3 turn-on voltage was 25 V. Its EL spectrum was almost identical with the PL spectrum of P. The maximum luminance of 200 cd m y2 3 was achieved at 29 V. Another device of ITOrPVKq P rAl could emit blue light with emission peak of 431 nm. The emission was 3 . resulting from P too. Both of the two devices showed good electroluminescence EL properties, and P was considered as a kind of blue 3 3

Novel binuclear europium β-diketone chelate used as red emitter in organic electroluminescent device

A novel binuclear europium and yttrium b -diketone complex EuY(TTA)6Phen2 was synthesized. The electroluminescent device using it as an emitter was fabricated. When the structure of device is ITO/TPD/EuY(TTA)6Phen2/Alq3/Mg:Ag, the emission peak of 613 nm and the luminance of 99 cd/m 2 at 11 V from the device have been achieved. The results showed that the new b -diketone chelate possessed better PL and EL properties, and film formation than those of Eu(TTA)3Phen. q 2000 Elsevier Science S.A. All rights reserved.

Novel efficient green electroluminescent conjugated polymers based on fluorene and triarylpyrazoline for light-emitting diodes

A series of novel light-emitting conjugated polymers based on fluorene and triarylpyrazoline were synthesized in good yields through Suzuki coupling reactions. The resulting polymers were characterized by NMR, FT-IR, elemental analysis, DSC, TGA and GPC. These polymers possess excellent thermal stability with glass transition temperatures (Tg) of 80–162 °C and onset decomposition temperatures (Td) of 376–387 °C. Cyclic voltammetry studies revealed that these polymers have good hole and electron transporting properties with LUMO energy levels of −2.97 to −2.98 eV and HOMO energy levels of −5.71 to −5.81 eV. All the polymers emit green fluorescence with very high photoluminescence (PL) quantum yields of 45–59%. Polymer light-emitting diodes (PLEDs) with the configuration ITO/PEDOT/polymer/Ba/Al were fabricated. All these devices showed bright green emission peaking at 494–500 nm with high maximum external quantum efficiencies of 0.6–2.53% and low turn-on bias voltages. The good light-emitting properties indicate that these polymers are new and promising candidates for electroluminescent materials that can be used to fabricate efficient polymer light-emitting diodes.

Studies on synthesis and EL properties of several novel squaraines

Abstract Several novel squaraines were synthesized and their structures were elucidated by IR, HNMR, MS and elementary analysis. Their photoluminescent (PL) and electroluminescent (EL) properties have been studied, which indicated that all of them had electrontransporting properties, and some had both electron, and hole-transporting properties. One of the squaraines was inserted between a cathode and an anode, and the single-layer-sandwiched device processed a redlightemitting ability under both low negative and low positive driven bias. It was regarded as one kind of promising material.