Effects of molecular shape on the photoluminescence of dyes embedded in a chiral polymer with a photonic band gap

Circularly polarized photoluminescence has been generated by embedding fluorescent guest molecules in a helically aligned polymer host with a selective reflection band, which coincides with the emission wavelength of the embedded dyes. We have investigated the photoluminescence from a range of guest molecules of varying shapes and found that one circular polarization is suppressed within the reflection band of the host independently of the shape of the guest molecules. However, just outside the band edges, there is an enhancement of the same polarization and the relative magnitudes of the enhancement at the two band edges is strongly influenced by the shape of the guest molecules. This effect has been understood from the ordering of the guest molecules in the polymer host. (C) 2003 Kluwer Academic Publishers.