THE EFFICIENCY AND TIME-DEPENDENCE OF LUMINESCENCE FROM POLY(P-PHENYLENE VINYLENE) AND DERIVATIVES

We report measurements of the quantum efficiency and time decay of pho toluminescence in the conjugated polymers poly(p-phenylenevinylene) (P PV) and poly(2-methoxy, 5-(2'ethyl-hexyloxy)-p-phenylenevinylene) (MEH -PPV). MEH-PPV is soluble and we measure values for the quantum yield for luminescence of order 35% for dilute solutions in toluene and chlo roform. By comparison of luminescence decay rates in solution and in s olid films we estimate luminescence efficiencies in solid films, which can be as high as 50% in partially conjugated PPV. Decay time distrib ution analysis of the luminescence reveals a broad distribution of dec ay rates, and this is consistent with the distribution of conjugation lengths known to be present in these materials. Exciton migration in b etter conjugated material results in narrower distributions of emittin g chromophores.