Long-lived photoexcited states in polydiacetylenes with different molecular and supramolecular organization

With the aim of determining the importance of the molecular and supramolecular organization on the excited states of polydiacetylenes, we have studied the photoinduced absorption spectra of the red form of $\mathrm{poly}[1,6-\mathrm{bis}(3,6-\mathrm{didodecyl}-N-\mathrm{carbazolyl})-2,4-\mathrm{hexadiyne}]$ ($\mathrm{p}\mathrm{o}\mathrm{l}\mathrm{y}\mathrm{D}\mathrm{C}\mathrm{H}\mathrm{D}-S$) and the results compared with those of the blue form of the same polymer. An interpretation of the data is given in terms of both the conjugation length and the interbackbone separation also in relation to the photoinduced absorption spectra of both blue and red forms of $\mathrm{poly}[1,6-\mathrm{bis}(N-\mathrm{carbazolyl})-2,4-\mathrm{hexadiyne}]$ (polyDCHD), which does not carry the alkyl substituents on the carbazolyl side groups. Information on the above properties is derived from the analysis of the absorption and Raman spectra of this class of polydiacetylenes.