Effects of photo-oxidation on conjugated polymer films

We have used two-photon photoemission as a sensitive monitor of the effects of photo-oxidation on poly[2-methoxy,5-(2'-ethylhexoxy)-1,4-phenylenevinylene] films. We observe a downward shift in the triplet exciton energy as well as a dramatic narrowing of the triplet exciton photoemission linewidth as photo-oxidation progresses. Both of these effects are attributed to changes in the physical and electronic structure of the film due to carbonyl defect formation on the polymer chains. This technique provides a highly sensitive probe of photo-oxidation which may be useful in the optimization of conjugated-polymer-based devices and displays. (C) 1997 American Institute of Physics.