A Photoelectrochromic Memory and Display Device Based on Conducting Polymers

We report a new photoelectrochromic system for information storage and display applications. This system is based on the electrochromic properties of thin films of electrochemically generated conducting polymers. These materials can be switched between two states of optical absorption: a highly absorbing, almost‐black film in the oxidized state, and an almost‐transparent film in the reduced state. On an n‐type semiconductor surface, oxidation of the conducting polymer requires illumination of the semiconductor surface. A thin film of conducting polymer photoelectrochemically generated onto a semiconductor surface can thus be reversibly bleached by a cathodic potential and blackened by anodic potential simultaneous with a light pulse. Such a device works as an optical memory which can be erased electrically and written optically with a scanning modulated light beam. We report on initial studies of the n‐Si/poly(N‐methylpyrrole) system in acetonitrile electrolyte.