PICOSECOND HOPPING RELAXATION IN CONJUGATED POLYMERS

The energy relaxation of optical excitations in poly(p-phenyl-phenylen evinylene) (PPPV) and PPPV blended in polycarbonate (PC) is investigat ed by means of picosecond time-resolved luminescence spectroscopy. In PPPV a pronounced dependence on the photon energy of the excitation la ser is found. For excitation into the tail states of the inhomogeneous ly broadened density of states distribution, the spectral shape of the luminescence remains almost constant with time. However, a transient red-shift is observed for excitation at higher energies. Experiments o n the diluted system PPPV/PC allow us to distinguish between intra-and inter-chain processes. The experimental results can be explained with a hopping model.