6533b7d6fe1ef96bd12663e7

RESEARCH PRODUCT

Untersuchungen zur Photoleitf�higkeit von alkoxysubstituierten Oligo- und Poly(1,4-phenylenethenylen)en

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Investigations on the Photoconductivity of Alkoxy Substituted Oligo- and Poly(1,4-phenyleneethenylene)s The photoreactivity and the photoconductivity of the mono- and dialkoxy substituted oligo- and poly(1,4-phenyleneethenylene)s 1/1′a-n were investigated in order to optimize the photoconducting properties of these materials. Increasing the length of the side chains enhances the average length of the main chain during the polycondensation and decreases the band gap till the limit of convergence is reached. The highest photoconductivity was observed for the 2,5-dipropyloxy system 1/1′j. Longer side chains render the charge transfer from chain to chain more difficult. The measurements were performed in dispersion layers and related to the industrial standard 3. Compound 1m was also measured in a pure state as transparent film and compared to a poly(N-vinylcarbazole) film which shows a dye-sensitized photoconductivity. In both cases the optimized systems 1/1′ were markedly superior to the standards. The highest sensitivity could be observed for wavelengths λ lying close to the absorption maxima λmax. The compounds 1/1′ have a high photostability on irradiation with visible light; however, they are rapidly destroyed by UV light (254 nm).