Enhanced photoluminescence of polyfluorene by incorporation of Al-doped ZnO nanoparticles

Photoluminescent and structural properties of nanocomposite films consisting of green-emitting polyfluorene (PF) and Al-doped ZnO (AZO) nanoparticles were investigated. Topographical analysis shows that AZO nanoparticles can be homogeneously dispersed in PF films with less than 10wt.% AZO. Photoluminescence of the composite films was investigated under wavelength selective excitation of AZO. Photoexcitation with laser energy below the AZO bandgap produces a slight increase in the PF emission intensity with increasing AZO concentration, accompanied by a spectral blueshift. These effects are attributed to separation of polymer chains and twisting of the PF backbone as revealed by Raman spectroscopy. On the other hand, photoexcitation above the AZO bandgap shows a remarkable enhancement, with the intensity at 5–10 wt.% AZO being three times greater than that of pure PF. The luminescence enhancement is attributed to the efficient transfer of energy from AZO nanoparticles to PF. ► Composites of polyfluorene (PF) and Al-doped ZnO (AZO) particles were investigated. ► Photoexcitation below AZO bandgap produces a slight increase in PF emission. ► Stronger enhancement is achieved when composites are excited above AZO bandgap. ► The enhancement is attributed to transfer of excitation energy from AZO to PF.