Synthesis and characterisation of polyfluorenes with light-emitting segments

We present the synthesis and characterisation of two copolymers. They consi sts of poly(9-hexyl-9-(2'-ethylhexyl)fluorene) (HEH-PF) with a small amount of another polymer with a narrow band-gap. The synthetic route was designe d to allow the incorporation of only one low band-gap segment per polymer c hain. Photoluminescence measurements showed that energy transfer from the P F-segments to the low band-gap segments did occur. In the solid state, all emissions were detected from the low band-gap segments with photoluminescen ce quantum yields up to 68%, One copolymer showed a low threshold for lasin g (2 muJ/cm(2)) in a microcavity device.