Synthesis and characterization of light-emitting materials composed of carbazole, pyrene and fluorene

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 (Ia–If) were examined in solutions, thin films and solid states, respectively. All of them showed relative high quantum yields both in solutions (Φs: 0.70–0.83) and in films (Φf: 0.17–0.34). Light-emitting diode using Ie as an emissive layer was fabricated in the ITO/poly(3,4-ethylenedioxythiophene) doped with poly(styrenesulfonate) (PEDOT:PSS)/Ie/2, 2′, 2″-(1, 3, 5)-benzene-triyl)tris[1-phenyl-1H-benzimidazole] (TPBI)/Al configuration. The maximum emission wavelength of the device was 496 nm. The maximum luminance and electroluminescence efficiency was 1000 cd/m2 and 0.41%, respectively.