Ultrafast study of spontaneous emission from conjugated polymer microcavities

Results are presented of femtosecond photoluminescence spectroscopy and photoluminescence quantum efficiency measurements of a planar conjugated polymer microcavity consisting of a layer of poly($p$phenylenevinylene) sandwiched between a dielectric mirror and an evaporated metallic layer. By comparison with measurements of a similar structure in the absence of the metallic mirror it is shown that the spontaneous emission rate is not increased notably due to the optical confinement of the microcavity, even though the emission is significantly enhanced in the forward direction. The time-resolved photoluminescence spectra highlight the rapid vibrational relaxation and energy migration of excitons that occur in conjugated polymers.