VISIBLE AND INFRARED OPTICAL-CONSTANTS OF ELECTROCHROMIC MATERIALS FOR EMISSIVITY MODULATION APPLICATIONS

Electrochromic materials are being studied for applications involving infrared emissivity modulation. The materials being investigated are a morphous WO3 and poly-crystalline WO3, NiO, and Ta2O5. Hydrogen ions a re intercalated into and deintercalated from the films leading to chan ges in the optical properties of the materials. Visible and infrared e llipsometry are used to measure the optical constants of these materia ls in various states of ion intercalation and to determine the reversi bility of the reactions. The spectral range for the optical constants determination is from 0.3 to 14 mu m. Simulations of electrochromic de vice structures using these optical constants show an emissivity modul ation greater than 50% for wavelengths near the peak of the room tempe rature blackbody curve. (C) 1998 Elsevier Science S.A.