Strong reduction of interchain interaction by bridged chain substitution in luminescent phenylenevinylene thin films

The strong reduction of interchain interaction in poly-(2,5-dialkoxy-1,4-ph enylenevinylene) films with a 2,5 O-(CH2)(12)-O closed chain substitution ( bridged PPV), engineered to reduce the molecular packing in the solid state , is reported. Evidence of this effect unambiguously stems from the systema tic comparison between the optical properties of a series of dialkoxy-PPV d erivatives with bridged and open chain side groups. Reduction of interchain energy relaxation channels explains the close similarity between the optic al spectra of bridged-PPV films and solutions, the higher photoluminescence efficiency and the lower threshold for the observation of spectral line na rrowing in the solid state. (C) 1999 American Institute of Physics. [S0003- 6951(99)04840-8].