Optical spectroscopies of excited states in poly(para phenylene vinylene)

We have applied a multitude of continuous wave and pulsed optical spectrosc opies to thin films of unsubstituted poly(para-phenylene vinylene) (PPV) wi th photoluminescence quantum efficiency greater than or equal to 30%. Laser action in thin films, microdisks and microrings has been demonstrated. The threshold for lasing is comparable to other PPV derivatives. Electroabsorp tion unambiguosly shows that the mA(g), state is located at 3.4 eV. At high er photon energies no large polarizability of excited states could be found . The photoinduced absorption spectrum which contains both polaron and trip ler excitations is very weak, showing a relatively defect free polymer.