Influence of electric field on the photoluminescence of a liquid crystalline monosubstituted polyacetylene

It has been shown recently that strong photoluminescence (PL) can occur in monosubstituted polyacetylenes (PAs). In this letter, we investigate the PL of tetrahydrofuran solutions of a highly luminescent liquid crystalline PA, poly(11-{[4′-heptoxy-4-biphenylyl)carbonyl]oxy}-1-undecyne) (PBU), under the influence of direct current electric fields. The applied electric fields can dramatically tune the PL structures of a moderately concentrated PBU solution (∼11.3 mM) at and above an electric field threshold of about 3×105 V/m. Combined with the director simulations, our results indicate that the electrically induced molecular reorientation and intermolecular interaction are responsible for the observed spectral changes.