Time resolved photoluminescence spectra of PPV film: heterogeneity and excited state relaxation

The photoluminescence (PL) spectra and PL decays of poly-p-phenylene vinylene (PPV) film prepared by the solvent-free, room temperature UV polymerization method were studied at 300 and 77 K. The analysis of the emission wavelength dependent luminescence decays of PPV film showed a lifetime distribution that varied in a systematic manner with emission wavelength. The oscillatory variation of PL decay (and average lifetime) with emission wavelength at 77 K is a new result. These results are consistent with the model that the PL of PPV film is due to energetically disordered excitons and thermally activated PL quenching is a dominant mechanism.