Alignment of Conjugated Polymers in a Nematic Liquid-Crystal Host

A general procedure, solvent-induced homogeneous dispersion, SIHD, is presented to incorporate and align conjugated polymers into a nematic liquid-crystal host. We report the investigation of the dye, N‘,N‘-bis(2,6 dimethylphenyl)-3,4,9,10, perylenetetracarboxylic dimide (PERY), and a conjugated polymer, poly[2-(2‘ethylhexyloxy)-5-methoxy-1,4-phenylenevinylene] (MEH−PPV), aligned in a low molecular weight nematic liquid-crystal matrix, 4- n -pentyl-4‘-cyanobiphenyl (5CB). Order parameters obtained for the guests from polarized absorption and fluorescence spectra are 0.46, 0.24, and 0.30 for PERY, MEH−PPV ( M n = 8.6 × 10 4 ), and MEH−PPV ( M n = 1.1 × 10 5 ) in 5CB, respectively. The liquid-crystal host provides a unique environment in which to study the conjugated polymer in a highly extended conformation. To this end, we discuss the relationship between polymer conformation and fluorescence, the line shape of the spectra, and the interchromophore/interchain versus intrachromophore/intrachain resonance energy transfer processes.