A theoretical study on photoexcitations in poly(p-phenylene vinylene)

By applying a femtosecond electric pump pulse to a poly(p-phenylene vinylene) (PPV) molecule, we theoretically investigate the photoexciting process. The simulations are performed within the framework of an extended version of one-dimensional Su–Schrieffer–Heeger tight-binding model combined with a nonadiabatic evolution method. We obtain excitons, biexcitons, as well as high-energy excitons. Their yields are calculated and it is found that they are determined by the photoexciting energy. Especially, we obtain a relation between their photogenerations and the photoexciting energies, which is helpful for optoelectronic applications of organic semiconductors. In addition, effect of the photoexciting intensity on the photogeneration of high-energy excitons, which contribute to free charges generation, is discussed.