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 photolu minescence (PL) quantum efficiency in comparison with unsubstituted or mono substituted polyacetylene. The polarization dependence of PL and Raman scat tering of PDPA-nBu and PHxPA have been studied in order to clarify the emis sion mechanism. Assuming the model of short polyene conjugation length in t he 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 (C) 2001 Elsevier Science B.V. All rights reserved.