Third-order optical susceptibility of ordered and disordered polyfluorene thin films

Abstract Third-order optical susceptibility, χ (3) , of a disordered thin film and two types of ordered thin films of poly(9,9-dioctylfluorene) are determined by electroabsorption measurements. In an ordered thin film consisting of planar polymer chains, χ (3) increases by 40% than that in a disordered thin film although the increase is considerably smaller than that reported for polythiophene derivatives. The reason for the small increase is discussed by comparing with the maximum χ (3) values of other conjugated polymers.