Polychromophores comprised of rigid-flexible alternating polyethers have been synthesized. In these polymers, the rigid part of the main chain is a quinquephenyl fluorophore decorated with two second generation Frechet-type side dendrons, while the flexible part is an aliphatic chain of 11 or 12 methylene groups. The effect of the length of the flexible spacer on the photoluminescence of these dendronized polyethers was examined in solution and in the solid state. It was found that even a subtle change in this length, from 11 to 12 methylene groups, had a strong effect on the fluorescence quantum yield of thin films, a fact which is of the greatest importance for the potential applications of these polymers as OLEDs.