Poly(fluorenevinylene) derivatives by Heck coupling: Synthesis, photophysics, and electroluminescence

다국어 초록 (Multilingual Abstract)

<P>Three new poly(fluorenevinylene) derivatives were synthesized, characterized, and used as emissive materials in light-emitting diodes (LEDs). They were synthesized by Heck coupling of 9,9-dihexyl-2,7-divinylfluorene with 2,7-dibromo-9,9-dihexylfluorene, 2,3-bis(4-bromophenyl)quinoxaline, or 2,5-bis(4-bromophenyl)-3,4-diphenylthiophene to afford the polymers F, Q, and T, respectively. Polymers F and Q had medium number–average molecular weights (M<SUB>n</SUB> ˜ 14,000) with relatively narrow polydispersity (1.3–1.6), while T was obtained as an oligomer (M<SUB>n</SUB> ˜ 4000). All polymers were soluble in common organic solvents, such as tetrahydrofuran (THF), chloroform, dichloromethane, and toluene. They emitted blue-greenish fluorescence light in dilute THF solution (444–491 nm), with photoluminescence (PL) quantum yields of 0.32–0.54, and in thin film (453–488 nm). LEDs with the configuration of ITO/PEDOT-PSS/Polymer/Li:Al were fabricated and evaluated. The electroluminescence (EL) spectra of the Q and F polymers were very broad covering the blue–green–red region, whereas the spectrum of the polymer T was almost purely blue. The threshold electrical field for light emission of the devices was almost the same (˜1.75 MV/cm). The external quantum efficiency of the devices of polymers Q and F was about 1.0 × 10<SUP>−3</SUP>%, whereas that of polymer T was ˜3.0 × 10<SUP>−5</SUP>%. The fluorescence lifetime of polymers F and Q was significantly longer than that of the polymer T. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 4494–4507, 2006</P>
<B>Graphic Abstract</B>
<P>Soluble poly(fluorenevinylene) derivatives F, Q, and T were synthesized by Heck coupling. They emitted blue-greenish light both in solution and in thin film, with photoluminescence emission maximum at 444–491 nm. Light emitting diodes with the configuration ITO/PEDOT-PSS/Polymer/Li:Al emitted light covering the blue–green–red region for the polymers F and Q, whereas this device emitted almost pure blue light for the polymer T.
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