A light activated photoelectrochromic device is formed of a two-component system formed of a photoactive charge carrier generating material and electrochromic material (plus an elecrolyte). Light interacts with a semiconductive material to generate hole-electron charge carriers which cause a redox reaction...http://www.google.de/patents/US6118572?utm_source=gb-gplus-sharePatent US6118572 - Photochromic, electrochromic, photoelectrochromic and photovoltaic devices
