Photoexcitations in disubstituted polyacetylene: solitons and polarons

We studied the photoexcitations in films of disubstituted polyacetylene, a rc-conjugated polymer with degenerate ground state. We found that the polym er in its pristine form supports charged and neutral topological soliton ex citations. Photo-oxidized films or polymer/C-60 blends show, in addition, p olaron excitations. At the same time the polymers show a strong emission ba nd with high quantum efficiency, which leads to stimulated emission in thin films and lasing in cylindrical mu -cavities. These excitation properties are unique among polymers of both degenerate and non-degenerate ground stat e. (C) 2001 Published by Elsevier Science B.V.