Photocarrier generation and transport inσ-bonded polysilanes

Abstract

Polysilanes, even those containing no π electrons, are found to be excellent photoconductors. In the materials studied to date, only holes are mobile but they have a well-defined mobility of about ${10}^{\mathrm{-}4}$ ${\mathrm{cm}}^2$/V?at room temperature. In poly(phenylmethylsilane), the material we have studied most intensely, the hole-generation quantum efficiency is about 1% at high electric fields and the experimental results indicate that the holes are generated when excitons, formed when a photon is absorbed, diffuse to the surface of the film. The exciton diffusion length is found to be 500 Å. These results help confirm the existence of extensive conjugation among σ bonds in polysilanes.