Dynamic Light Modulation in an Electrochromic Window consisting of Polyaniline, Tungsten Oxide and a Solid Polymer Electrolyte

Abstract

The electrochemical and optical properties of an electrochromic window consisting of the two complementary electrochromic materials, polyaniline (PANI) and tungsten oxide (WO3), have been investigated. Both PANI and WO3 were electrochemically deposited on indium-tin oxide (ITO) glass substrates. Using the solid organic polymer electrolyte, poly(2-acrylamido-2-methyl-propane-sulfonic acid) (PAMPS), PANI and WO3 were glued together. By applying a potential of ∼1.5V across the two external ITO contacts, we are able to modulate the light transmission, also in the near-infrared region (700–3000 nm), where about half of the solar energy lies, indicating that these ‘smart windows’ may significantly contribute to future energy savings in buildings. In order to study each of the electrochromic layers in the window, we have fabricated windows with holes in the electrochromic coatings, one window with a hole in the PANI film and another with a hole in WO3. This enables us to study the optical properties of PANI and WO3 separately.