Spectroscopic and Photoluminescent Properties of Nanostructured Polyfluorenes/TiO2 Composite Films used for OLEDs

Abstract

In this work we present spectroscopic and photoluminescent properties of nanostructured polymeric composite films of nanocrystalline TiO₂ and polyfuorenes (PF+nc-TiO₂). The films were deposited onto glass and KBr substrates by spin-coating PF-in-toluene solution with embedding of 5-nm thick nc-TiO₂ particles. The nc-TiO₂ wt concentration embedded in PF was chosen as 1%, 2% and 4%. The FTIR, FTR, UV-VIS-NIR and photoluminescence characterization were carried-out to study the influence of oxide nanoparticles on the absorption spectra, molecular structures and emissive luminescence of the composites. It was shown that the presence of TiO₂ nanoparticles results in improvement of charge separation of carriers generated by light excitation. Under a short wavelength excitation, in some samples a PL enhancement was observed. Under normal or long wavelength excitation, PF fluorescence quenching occurred for all the composites. Aging process of the composites was also investigated.