Interchain photoluminescence in poly(phenylene vinylene) derivatives

Abstract

We calculate that in cyano-substituted poly(phenylene vinylene), CN-PPV, and poly[2-methoxy, 5-(2\ensuremath{'} -ethyl-hexyloxy)phenylene vinylene], MEH-PPV, the lowest-energy arrangement has the chains parallel, with the perpendicular distance between chains 3.4 \AA{} in the former case, 4.1 \AA{} in the latter. Although there is evidence that most of the excitations created by above-band-gap light are polaron pairs or excimers in both cases, only those in CN-PPV luminesce because the smaller interchain distance results in a much larger matrix element for emission.