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Light-emitting Materials (light-emitting + material)

Distribution by Scientific Domains

Polymers and Materials Science	80%

Selected Abstracts

Origins of Improved Hole-Injection Efficiency by the Deposition of MoO3 on the Polymeric Semiconductor Poly(dioctylfluorene- alt -benzothiadiazole)

ADVANCED FUNCTIONAL MATERIALS, Issue 23 2009
Yasuo Nakayama
Abstract The electronic structure of the interfaces formed after deposition of MoO3 hole-injection layers on top of a polymer light-emitting material, poly(dioctylfluorene- alt -benzothiadiazole) (F8BT), is studied by ultraviolet photoelectron spectroscopy (UPS), X-ray photoelectron spectroscopy and metastable atom electron spectroscopy. Significant band bending is induced in the F8BT film by MoO3 "acceptors" that spontaneously diffuse into the F8BT "host" probably driven by kinetic energy of the deposited hot MoO3. Further deposition leads to the saturation of the band bending accompanied by the formation of MoO3 overlayers. Simultaneously, a new electronic state in the vicinity of the Fermi level appears on the UPS spectra. Since this peak does not appear in the bulk MoO3 film, it can be assigned as an interface state between the MoO3 overlayer and underlying F8BT film. Both band bending and the interface state should result from charge transfer from F8BT to MoO3, and they appear to be the origin of the hole-injection enhancement by the insertion of MoO3 layers between the F8BT light-emitting diodes and top anodes. [source]

Synthesis and photophysical properties of a novel semiconducting polymer

POLYMERS FOR ADVANCED TECHNOLOGIES, Issue 1-2 2004
Hongmin Huang
Abstract An alternating copolymer containing triphenylamine (TPA) and cyano-substituted benzene moieties, TPA-CNPPV was synthesized using the Wittig reaction. The monomers and polymer were characterized by H-NMR, FT-IR and mass spectroscopy (MS). The polymer shows good solubility in common organic solvents and excellent film-forming ability. Thermogravimetric analysis (TGA) demonstrates that the polymer has a degradation temperature (TD) of 600°C; differential scanning calorimetry (DSC) result indicates that the glass transition temperature (Tg) of TPA-CNPPV is 160°C, suggesting high thermal stability. The photophysical properties of the light-emitting material were investigated in both solution and spin-coated film. Photo-isomerization of the polymer was investigated by UV-vis and fluorescence spectra. The interaction between TPA-CNPPV and C60 was studied by fluorescence quenching. Copyright © 2004 John Wiley & Sons, Ltd. [source]

Synthesis and properties of novel conjugated poly(silylacetylene silazane)s

JOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 12 2004
Ji Dong Hu
Abstract A series of novel conjugated polymers, poly(silylacetylene silazane)s having different substituents, were prepared by ammonolysis of the corresponding ,,,-dichlorosilyleneacetylene oligomers. The structures and properties of the poly(silylacetylene silazane)s were characterized by Fourier transform infrared, 1H, 13C, 29Si NMR, and elemental analyses, gel permeation chromatography, thermogravimetric analysis, differential scanning calorimetry, and spectrofluorophotometry. The resulting polymers had good thermal properties and were moderately fluorescent. Their thermal stability was improved, and obvious red shift was observed when a phenyl substituent was attached on a silicon atom of polymers in the emission spectra. These polymers have the potential to be used as light-emitting materials with good thermal stability. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 2897,2903, 2004 [source]

Highly soluble diphenylfluorene-based cardo copolyimides containing perylene units,

POLYMERS FOR ADVANCED TECHNOLOGIES, Issue 7-8 2006
Shengang Xu
Abstract Two series of novel ternary copolyimides containing perylene and fluorene units in the backbone were synthesized by one-step polycondensation of diamine (4,4,-(9H-fluoren-9-ylidene)bisphenylamine, FBPA) with perylene dianhydride (3,4,9,10-perylenetetracarboxylic dianhydride, PTCDA) and a comonomer [4,4,-(hexafluoroisopropylidene) diphthalic anhydride, 6FDA or 3,3,,4,4,-benzophenonetetracarboxylic dianhydride, BDTA]. The polymers were named as PFFx (PTCDA-FBPA-6FDA) and PFBx (PTCDA-FBPA-BTDA), respectively, and their chemical structures were identified by FT-IR spectra and elemental analyses. Perylene contents in the copolyimides were determined through a quantitative UV-vis spectroscopy method, which are in agreement with the values calculated from the added raw materials both for PFFx and PFBx. Gel permeation chromatography (GPC) measurement suggested that the weight average molecular weight (Mw) is in the range 2.1,5.09,×,104 and the molecular weight distribution (MWD) is 1.86,2.72 for PFFx, and those for PFBx are 2.64,4.73,×,104 and 2.44,2.92, respectively. Thermogravimetric analysis (TGA) measurements showed that the copolyimides are very thermally stable with a temperature of 10% weight loss (T10) in the range 546,563°C for PFFx, and 538,548°C for PFBx. The copolyimides also have good solubility in common organic solvents such as chloroform and tetrahydrofuran. These unique properties can be attributed to the existence of the bulky diphenylfluorene moieties in the polymer backbone. All the copolyimides can emit strong fluorescence both in solution and in films, which make them possibly be used as thermostable light-emitting materials for organic light-emitting diodes. Copyright © 2006 John Wiley & Sons, Ltd. [source]

Substituent Effect To Prevent Autoxidation and Improve Spectral Stability in Blue Light-Emitting Polyfluorenes

CHEMISTRY - A EUROPEAN JOURNAL, Issue 15 2005
Jiu Yan Li Dr.
Abstract A group of fluorene-based polymers, PF-1SOR and PF-2SOR, were synthesized and characterized as blue light-emitting materials. PF-1SOR and PF-2SOR displayed nematic liquid crystalline mesophase in films cast from solution. Compared with conventional polyfluorene, PF-1SOR and PF-2SOR display blue-shifted UV absorption and structureless blue fluorescence. The photoluminescence spectra of PF-1SOR and PF-2SOR were found insensitive against thermal treatment in air up to 200°,C and the blue electroluminescence in their light-emitting devices was independent of the driving voltage. Compared to the conventional polyfluorenes, the improved spectral stability of these polymers is attributed to the anti-oxidization effect of (3,5-di(tert -butyl)phenoxy)sulfonyl side groups attached to the backbone. [source]