NEW VARIABLE-REFLECTIVITY ELECTROCHROMIC MATERIALS FOR SMART WINDOWS-

"SMART" WINDOWS ARE UNDER STUDY FOR IMPROVING THE EFFICIENCY OF HEATING AND COOLING IN BUILDINGS. SUCH WINDOWS WOULD HAVE A CONTINUOUSLY ADJUSTABLE OPTICAL DENSITY. AN ALL-SOLID-STATE THIN-FILM ELECTROCHROMIC MULTILAYER COATING ON GLASS OR PLASTIC MIGHT BE EMPLOYED TO CONSTRUCT SUCH A DEVICE. WORK IN THIS LABORATORY AND OTHERS HAVE IDENTIFIED A NEW CLASS OF MATERIALS, "REFLECTIVE ELECTROCHROMICS," IN WHICH THE OPTICAL REFLECTIVITY MAY BE MODULATED BY REVERSIBLE ELECTRO- CHEMICAL ION-INSERTION REACTIONS. IN EFFECT, THESE REACTIONS GIVE RISE TO VARIATIONS IN FREE ELECTRON DENSITY IN THE HOST COMPOUNDS, WHICH ALSO AFFECTS THE OPTICAL REFLECTANCE PROPERTIES. USING THESE NEW MATERIALS, A VARIABLE REFLECTANCE "SMART" WINDOW COULD BE CONSTRUCTED. THIS PROGRAM WILL STUDY SEVERAL NEW POTENTIAL REFLECTIVE ELECTROCHROMIC MATERIALS THAT ARE WIDE BANDGAP SEMICONDUCTORS (TO MINIMIZE SOLAR ABSORPTION) AND THAT EXHIBIT BOTH REVERSIBLE ALKALI ION-INSERTION ELECTROCHEMISTRY AND HAVE HIGH MOBILITIES FOR CONDUCTION BAND ELECTRONS. SUCCESSFUL CANDIDATES WILL UNDERGO FURTHER OPTIMIZATION IN PHASE II AND ALSO WILL BE INTEGRATED INTO SOLID-STATE WINDOW PROTOTYPES.