PHOTOLUMINESCENCE SPECTRA OF OLIGO-PARAPHENYLENEVINYLENES - A JOINT THEORETICAL AND EXPERIMENTAL CHARACTERIZATION

We present a joint theoretical and experimental characterization of th e absorption and photoluminescence spectra of oligo-paraphenylenevinyl enes containing from 2 to 5 phenylene rings, Attention is paid to the emission spectra and their vibronic progressions in order to shed ligh t on the geometry relaxation phenomena in the lowest singlet excited s tate, The results indicate that the relaxation energy in the excited s tate increases with inverse chain length. For long conjugated chains, the relaxation energy of the bound electron-hole pair is extrapolated to be of the order of 0.14 eV and the most significant part of the geo metry deformations are found to spread over a length of about 20 Angst rom. (C) 1997 Elsevier Science B.V.