Long-Range Excitons in Optical Absorption Spectra of Electroluminescent   Polymer Poly(para-phenylenevinylene)
  The component of photoexcited states with large spatial extent is investigated for poly(para-phenylenevinylene) using the intermediate exciton theory. We find a peak due to long-range excitons at the higher-energy side of the lowest main feature of optical spectra. The fact that the onset of long-range excitons is located near the energy gap is related to the mechanisms of large photocurrents measured in such energy regions. We show that a large value of the hopping integral is realistic for characterizing optical excitations. 
Kikuo Harigaya (ETL - Japan)