Photophysical properties and quantum chemical studies of poly(2,7-9,9'-dihexylfluorene-dyil)

this work reports the photophysical properties (excitation and fluorescence spectra, fluorescence quantum yield, fluorescence lifetimes) of the poly(2,7-9,9'-dihexylfluorene-dyil) in dilute solutions of four solvents (toluene, tetrahydrofuran, chloroform and ethyl acetate) as well as the properties in solid state. photoluminescence showed spectra characteristic of disordered α-backbone chain conformation. simulation of the electronic absorption spectra of oligomers containing 1 to 11 mers showed that the critical conjugation length is between 6 and 7 mers. we also estimated the theoretical dipole moments which indicated that a coil conformation is formed with 8 repeating units per turn. we also showed that some energy transfer process appears in solid state which decreases the emission lifetime. furthermore, based on luminescent response of the systems herein studied and electroluminescent behavior reported on literature, both photo and electroluminescence emissions arise from the same emissive units.