Optical properties of disubstituted polyacetylene thin films

We have studied the optical properties of thin films of novel disubstituted acetylene polymers such as poly(1-phenyl-2-p-n-butylphenylacetylene) (PDPA-nBu) and poly(1-n-hexyl-2-phenylacetylene) (PHxPA), that show high photoluminescence (PL) quantum efficiency in comparison with unsubstituted or monosubstituted polyacetylene. The polarization dependence of PL and Raman scattering of PDPA-nBu and PHxPA have been studied in order to clarify the emission mechanism. Assuming the model of short polyene conjugation length in the acetylene polymers, we estimate the average conjugation length from the respective stretching vibration frequency of the carboncarbon double bond. The emission mechanism of PHxPA and PDPA-nBu is discussed in relation with the electronic excited states of these polymers