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Excellent Thermal (excellent + thermal)

Distribution by Scientific Domains
Polymers and Materials Science100%

Terms modified by Excellent Thermal

  • excellent thermal stability
    		•

    Selected Abstracts

    Highly Efficient Red Phosphorescent OLEDs based on Non-Conjugated Silicon-Cored Spirobifluorene Derivative Doped with Ir-Complexes

    ADVANCED FUNCTIONAL MATERIALS, Issue 3 2009
    Yi-Yeol Lyu
    Abstract A novel host material containing silicon-cored spirobifluorene derivative (SBP-TS-PSB), is designed, synthesized, and characterized for red phosphorescent organic light-emitting diodes (OLEDs). The SBP-TS-PSB has excellent thermal and morphological stabilities and exhibits high electroluminescence (EL) efficiency as a host for the red phosphorescent OLEDs. The electrophosphorescence properties of the devices using SBP-TS-PSB as the host and red phosphorescent iridium (III) complexes as the emitter are investigated and these devices exhibit higher EL performances compared with the reference devices with 4,4,- N,N,-dicarbazole-biphenyl (CBP) as a host material; for example, a (piq)2Ir(acac)-doped SBP-TS-PSB device shows maximum external quantum efficiency of ,ext,=,14.6%, power efficiency of 10.3 lm W,1 and Commission International de L'Eclairage color coordinates (0.68, 0.32) at J,=,1.5,mA cm,2, while the device with the CBP host shows maximum ,ext,=,12.1%. These high performances can be mainly explained by efficient triplet energy transfer from the host to the guests and improved charge balance attributable to the bipolar characteristics of the spirobifluorene group. [source]

    Solution-Processed Solid Solution of a Novel Carbazole Derivative for High-Performance Blue Phosphorescent Organic Light-Emitting Diodes

    ADVANCED MATERIALS, Issue 37 2010
    Shanghui Ye
    Blue light: Incorporation of two fluorenyl rings into a phenyl group at the C9 position of fluorene builds a bulky and rigidly tetrahedral framework, which is functionalized by two carbazole groups. This molecule possesses excellent thermal and morphological stability, miscibility to the phosphorescent dopant, and high triplet energy, leading to narrow blue phosphorescent emission. [source]

    Synthesis and characterization of high molecular weight hexafluoroisopropylidene-containing polybenzimidazole for high-temperature polymer electrolyte membrane fuel cells

    JOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 16 2009
    Guoqing Qian
    Abstract A high molecular weight, thermally and chemical stable hexafluoroisopropylidene containing polybenzimidazole (6F-PBI) was synthesized from 3,3,-diaminobenzidine (TAB) and 2,2-bis(4-carboxyphenyl) hexafluoropropane (6F-diacid) using polyphosphoric acid (PPA) as both the polycondensation agent and the polymerization solvent. Investigation of polymerization conditions to achieve high molecular weight polymers was explored via stepwise temperature control, monomer concentration in PPA, and final polymerization temperature. The polymer characterization included inherent viscosity (I.V.) measurement and GPC as a determination of polymer molecular weight, thermal and chemical stability assessment via thermo gravimetric analysis and Fenton test, respectively. The resulting high molecular weight polymer showed excellent thermal and chemical stability. Phosphoric acid doped 6F-PBI membranes were prepared using the PPA process. The physiochemical properties of phosphoric acid doped membranes were characterized by measuring the phosphoric acid doping level, mechanical properties, and proton conductivity. These membranes showed higher phosphoric acid doping levels and higher proton conductivities than the membranes prepared by the conventional membrane fabrication processes. These membranes had sufficient mechanical properties to be easily fabricated into membrane electrode assemblies (MEA) and the prepared MEAs were tested in single cell fuel cells under various conditions, with a focus on the high temperature performance and fuel impurity tolerance. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 4064,4073, 2009 [source]

    Synthesis and characterization of thermally stable, high-modulus polyimides containing benzimidazole moieties

    JOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 8 2009
    Shuang Wang
    Abstract A series of novel benzimidazole-containing aromatic polyimides were prepared from synthesized 5,4,-diamino-2-phenyl benzimidazole (DAPBI), and commercial dianhydrides by the conventional two-step polymerization. The obtained films were amorphous and could afford flexible, transparent, and tough films with excellent thermal and mechanical properties. They showed high levels of tension strength of up to 234 MPa, modulus of up to 5.6 GPa without any stretching. According to thermal stability measurements, the glass-transition temperatures of the polymers were observed between 329 and 425 °C. The 5% weight-loss temperatures of most polyimides were above 600 °C in nitrogen. Excellent properties of these polyimides were proved to be attributed to the rigid-rod structure and hydrogen bond of intermacromolecular. SAXS and SEM results showed self-molecular orientation caused the formation of rod-like extended conformations. It was demonstrated that high degree of supramolecular order led to the increase of thermal stability and mechanical properties of the polyimide films. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 2024,2031, 2009 [source]