By mixing short polyethyleneoxide (PEO) chains end-grafted with azobenzene groups with long PEO chains together with a lithium salt, we obtained ionically conducting films whose conductivity can be modulated by UV light up to 90% of its dark value on a wide temperature range. From electrical (impedance spectroscopy) and structure measurements (SAXS), we can conclude that this behavior is essentially resulting from a localized process of freeing of charge carriers via the conformational change of the azobenzene molecules. This article mainly compares the results obtained with two different photosensitive derivatives.