EXCITONS, BIEXCITONS, AND THE BAND-GAP IN POLY(P-PHENYLENE VINYLENE)

The excited states of poly(p-phenylene vinylene) (PPV) are studied in the Su-Schrieffer-Heeger model appended by a long-range Coulomb intera ction. We have calculated the energy levels of singlet and triplet exc itons with odd and even parity, the biexciton state, and the onset of the continuum band in PPV; these results can comprehensively interpret relevant experimental data. More significantly, we have constructed t he wave function of the biexciton by using the Heitler-London method a nd calculated the binding energy and radius of the biexciton in conjug ated polymers.