Photoexcitation of Bipolaron in Conducting Polymers

We theoretically study the photoexcitation process in a conducting polymer with a non-degenerate ground state, where the carrier without spin is bipolaron. The dynamical simulation reveals a photoinduced phenomenon that a positive bipolaron is split into two polarons by absorbing one photon. The relaxation time of this photoinduced bipolaron-split is about 40 fs. It is predicted that this photoinduced phenomenon can be detected experimentally by observing the change of magnetic susceptibility.