PHOTOEXCITED STATES IN EPITAXIALLY ORIENTED POLYDIACETYLENE FILMS

We report the optical properties and photoinduced absorption spectra o f oriented poly [1,6-di(N-carbazolyl)-2,4-hexadiyne] (polyDCHD) grown by molecular epitaxy on a crystal of potassium acid phthalate. The abs orption spectra in polarized light show the high degree of alignment o f the polymeric chains obtained by this growth technique. The photoind uced absorption spectra show the typical structures (due to bipolarons and triplet excitons) already observed for the same polymer as a micr ocrystalline sample. The photoinduced signal is maximum when the pump beam is polarized perpendicularly to the chain axis direction. This is indicative of a direct interchain long-lived carrier generation, as a lready observed in other oriented conjugated polymers.