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Abstract: Three new trimers PV, FV and CV were synthesized by Heck coupling of 4(4-bromophenyl)-2,6-diphenylpyridine with substituted divinylbenzene, divinylfluorene and divinylcarbazole, respectively. They were very soluble in chloroform, dichloromethane, tetrahydrofuran and toluene. FV and CV were more thermally stable and showed higher glass transition temperature than PV. Their absorption maximum was located at 327–397nm with optical band gap of 2.53–2.73eV. FV and CV emitted blue-green light with emission maximum at 455–489nm while PV emitted green-yellow light with emission maximum at 496–530nm. Upon protonation, the trimer thin films displayed red-shifts of the emission maximum. The electrochemical and electroluminescent properties of the trimers were studied. Light-emitting diodes (LEDs) based on these trimers were fabricated. These LEDs showed bright blue light for FV, CV and bluish-green light for PV which are in line with their photoluminescence spectra. The maximum brightness was reached approximate 1000cd/m2 for PV, 380 for FV, and 400 for CV, at current density of 200mA/cm2. [Copyright &y& Elsevier]

Abstract: A series of blue light-emitting compounds with different molecular shapes were synthesized by the Pd/Cu-catalyzed Sonogashira coupling reaction. These compounds composed of hole-transporting group (carbazole) and strong fluorescent group (pyrene), which linked through 9,9-dihexyl-2,7-fluorene ethynylene. The photoluminescent (PL) and electroluminescent (EL) behavior of these compounds was investigated. [Copyright &y& Elsevier]

Abstract: A carbazole compound was synthesized by Knovenagel condensation and characterized by the measurements of 1H NMR, IR and melting point. A multilayer organic light-emitting diode (OLED) using this compound as an active layer was fabricated by vacuum-deposition. This OLED showed a turn-on voltage of approximately 4.5V and a maximum luminance of 910cd/m2. Additionally, the maximum luminous efficiency was found as 0.95cd/A, at this point the device luminance was measured as 146cd/m2 at an operating voltage of 7V. The coordinate value of CIE 1931 was calculated as (x, y)=(0.3843, 0.5345) from the electroluminescence (EL) spectrum, which suggested that the device can emit a yellow-green light. [Copyright &y& Elsevier]

Abstract: A series of ethynyl-linked π-conjugated light-emitting molecules with good photoluminescence properties were designed and synthesized through Pd/Cu-catalyzed Sonogashira coupling reaction. The main structure comprised of different fluorophors (pyrene, carbazole, and fluorene), which were linked with triple bonds in order to be screened for high emission efficiency. Optical properties of these synthesized compounds (I a –I f ) were examined in solutions, thin films and solid states, respectively. All of them showed relative high quantum yields both in solutions (Φ s: 0.70–0.83) and in films (Φ f: 0.17–0.34). Light-emitting diode using I e as an emissive layer was fabricated in the ITO/poly(3,4-ethylenedioxythiophene) doped with poly(styrenesulfonate) (PEDOT:PSS)/I e/2, 2′, 2″-(1, 3, 5)-benzene-triyl)tris[1-phenyl-1H-benzimidazole] (TPBI)/Al configuration. The maximum emission wavelength of the device was 496nm. The maximum luminance and electroluminescence efficiency was 1000cd/m2 and 0.41%, respectively. [Copyright &y& Elsevier]