Effect of fluorenone on the polyfluorenes with polar tri(ethylene oxide) side chains and their synthesis, characterization and photophysics

A series of fluorene-fluorenone copolymers constituted by 9,9-di(3,6,9-trioxadecyl)-fluorene and 9-fluorenone moieties in different molar ratios have been synthesized by Yamamoto coupling reactions. By means of the UV-Vis and PL emission spectra of solution and solid state film, the effect of fluorenone acting as an energy acceptor on the energy transfer process and the photophysics of the copolymers was investigated. In dilute solution, the fluorescence of the polyfluorene backbone was dominant and the energy transfer depended on the polymer concentration strongly. The energy transfer efficiency of the thin film was enhanced rapidly with increasing the fluorenone content and the phenomenon became more distinct after being annealed.