Synthesis and luminescent characteristics of fluorene-based polymers containing diacetylene unit

Various diacetylene-containing polymers for light-emitting diode were prepared by oxidative polymerization of the corresponding diethynyl or dipropargyl-terminated monomers. The resulting polymers with high luminescence and high molecular weights were soluble in common organic solvents such as chloroform, THF, toluene, etc., and could be easily cast to afford freestanding films. For example, the poly(9,9′-di-n-hexyl-2,7-diethynylfluorene) (PDHDEF) with excellent mechanical strength was stable up to 300°C without weight loss and found to be easily cross-linked by UV light or thermal treatment. The optical absorption spectrum of the solid film showed a peak at 390 nm while PL spectrum gave a main peak at 440 nm with two shoulder peaks at 470 and 520 nm. The PL characteristic studies of these polymer solution, film, cross-linked products and their EL properties were discussed.