Investigation of photogenerated excited states relaxation pathways for cis rich to trans rich poly(phenylacetylene)

We have investigated emission properties of a series of poly(phenylacetylene) samples with controlled amount of cis/trans ratio. We observed that both the emission efficiency and PL lifetime decrease with increasing cis content. These results seem to rule out the soliton model as the origin for the strong photoluminescence (PL) in PPAs. However, the PL results can be explained by the lower degree of stereoregularity with decreasing cis content resulting in short segments of cis PPA which give rise to strong PL due to the confinement effect.