Energy transfer to dopant molecules in polyfluorene films

TL;DRAbstract

Polyfluorene is a promising material for applications such as polymeric light-emitting diodes. Upon optical or electrical excitation it exhibits efficient blue fluorescence and is easily made into thin films by spin-coating from solution. Incorporating suitable dopant molecules in these films changes the emission colour. The energy transfer processes taking place have been investigated here by steady-state and time resolved fluorescence measurements. To assist in the analysis of these measurements, the optical constants of polyfluorene were found by ellipsometry. Both unaligned and aligned films exhibit uniaxial anisotropy. Unaligned films have their optical axis normal to the film surface and are optically negative. Aligned films have their optical axis oriented in plane, parallel to the rubbing direction and are optically positive. In aligned films, light polarized in the alignment direction experiences absorption twice as high as light incident on unaligned films. Temperature depend

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