Within a theoretical approach including both electron-phonon and electron-electron interaction terms, we investigate the relaxation processes of photoexcited states in oligomers and long chains of poly(paraphenylene vinylene), PPV. Our direct calculations indicate that in PPV the difference in relaxation energy between two polarons and one singlet [triplet] polaron-exciton decreases [increases] with the Hubbard U term; the long-range interaction V terms stabilize both the singlet and triplet polaron-excitons. The theoretical simulation of the photoinduced absorption spectra both for singlet and triplet states are in very a good agreement with experiment.