PICOSECOND TIME-RESOLVED PHOTOLUMINESCENCE OF PPV DERIVATIVES

We report some time-resolved luminescence measurements on the conjugat ed polymer, MEH-PPV, that show a marked dependence on the intensity of the excitation light. At low laser powers the excited state lifetime is longer than has been reported previously and is consistent with emi ssion from an interchain excitation that has low oscillator strength a nd hence a long natural radiative lifetime. We rationalise these data with a simple scheme that summarises the excited state kinetics in thi s and other conjugated, electroluminescent polymers.