Polysilylenes: charge carrier transport and photogeneration

Charge carrier transport and photogeneration in polysilylenes, specifically in poly[methyl(phenyl)silylene], are discussed. Electronic properties are influenced by electron delocalization along the silicon backbone. A model of disordered polarons seems to be adequate to describe the charge carrier transport properties. Dissociation of ion pairs in external electric field, which can be described in terms of the Onsager theory of geminate recombination, seems to be the main mechanism of the free charge carrier photogeneration. Polar additives or polar side groups attached to the polymer backbone locally modify the ionization energy of the polymer segments and energies of electrostatic interactions of charge carriers and the dipoles. These changes result in the creation of local states for charge carriers and in the formation of a potential well structure. If the side groups are photochromic species changing their dipole moments upon illumination, then a light-driven molecular switch can be proposed.