Sharp and red “single-chain” luminescence from poly[2,5-dialkoxy-1,4-phenylene vinylene] locked in ordered host matrix

We found that the luminescence profile of poly[2,5-di(3′,7′-dimethyloctyloxy)-1,4-phenylene vinylene] (OC10C10-PPV), which originally is an orange-emitting polymer, can red-shift significantly by ca. 30 nm (λmax: from 585 to 614 nm) and become very narrow (full width at half maximum: 30 nm) when doped into poly{2-[m-(3′,7′-dimethyloctyloxy)phenyl]-1,4-phenylene vinylene} (m-Ph-PPV). Due to the ordered structure of the host polymer, the effective conjugation length of the guest polymer is extended as if the chains were frozen. Surprisingly, the OC10C10-PPV chains can even be more tightly locked in the ordered m-Ph-PPV matrix than in the cooled neat OC10C10-PPV film at 5 K.