Excitons in poly(para-phenylenevinylene)

Abstract

We show that one-electron band theory fails to describe optical absorption in PPV and the absorption spectrum can be described only within a Coulomb-correlated model. The lowest optical state is an exciton, whose binding energy is estimated theoretically to be 0.90±0.15 eV. Measurements of the photoconductivity quantum efficiency in poly[2-methoxy,5-($2^{\mathcal{’}}$-ethyl-hexyloxy)-1,4 phenylenevinylene] reveal a binding energy in good agreement with the theoretical value.