An investigation of the emission solvatochromism of a fluorene-triarylamine copolymer studied by time resolved spectroscopy

The hole transporting fluorene-triarylamine copolymer poly{9,9-dioctylfluor ene-co-[N,N'-bis(4-methoxyphenyl)-N,N'-diphenyl-1,4-phenylenediamine]} [PFM O] has been investigated by absorption and emission spectroscopy as both sp in-coated films and solutions. The peak wavelength of the steady-state phot oluminescence emission and its decay time depend strongly on the dielectric constant of the solvent. The absorption spectrum is, however, largely inse nsitive to the choice of solvent. These observations suggest the presence o f a strongly polar excited state with a charge-transfer character.