ELECTROABSORPTION AND CHARGED-EXCITATION SPECTROSCOPY OF II-CONJUGATED POLYMERS

Electroabsorption (EA) and photoinduced absorption excitation (PAE) spectra for charged excitations have been measured for luminescent [poly(phenylene acetylene), PPA] and nonluminescent (polydiethynyl silane, PDES) pi-conjugated polymers at 80K, over the spectral range from 1.5 to 4 eV. Based on these measurements, a discussion of the locations of the singlet 1B(u) and A(g) states is presented, as well as an analysis of the first- and second-derivative nature of the EA lineshapes. It is argued that luminescence (or lack of) in these polymers depends on the location of an A(g) State in close proximity to the 1B(u) state.