A potential J aggregate molecular system: crystal packing and optical properties of 4,4'-bis(2,3,4,5,6pentafluorostyryl)stilbene

A preliminary condition for an organic semiconductor to display the appealing spectroscopic properties of J aggregates in the solid state is to posses a favourable molecular packing. 4,4'-Bis(2,3,4,5,6-pentafluorostyryl)stilbene crystallizes in a "brickwall" fashion that is promising with respect to the possible formation of J aggregates in the solid. We report a systematic spectroscopic investigation of 4,4'-bis(2,3,4,5,6-pentafluorostyryl)stilbene in powder, solution, thin films and single crystals. Solutions of 4,4'-bis(2,3,4,5,6-pentafluorostyryl)stilbene with increasing concentration starting from 10(-6) M have been prepared and characterized. Thin films have been grown by high vacuum sublimation on substrates with different hydrophobicity (viz. sapphire, mica and HOPG) in order to explore the effect of substrate surface energy on the photoluminescence (PL) properties of thin films. Single crystals have been grown by vacuum sublimation and the corresponding polarized photoluminescence spectra have been measured at 4 K. (C) 2003 Elsevier Science B.V. All rights reserved.