Theory predicts that an electron or hole added to a conjugated polymer chain causes the chain to distort, forming a large polaron. Recent calculations of the three-dimensional band structure of trans-polyacetylene, t-PA, and poly(phenylene vinylene), PPV, have obtained values for the interchain coupling that are large enough to destabilize the polaron. Nevertheless, there is evidence that polarons exist in these materials. We show that the existence of chain endings and other conjugation breaks can stabilize the polaron in actual samples.

• Received 2 November 1992

DOI:https://doi.org/10.1103/PhysRevLett.70.1505