ECONOMICAL PHOTOCHROMIC FILMS FOR SOLAR THEMAL CONTROL

THE GOAL OF THIS WORK IS TO DEVELOP A ROBUST THIN FILM COATING, LESS THAN 1 UM THICK, THAT CAN BE APPLIED TO SURRACES, RENDERING THEM PHOTOCHROMIC IN SUNLIGHT WITH RESPECT TO BOTH THE VISIBLE AND NEAR INFRARED COMPONENTS OF THE SOLAR SPECTRUM. APPLIED TO WINDOWS THESE SINGLE LAYER "CHROMOGENIC" COATINGS ARE PROJECTED BY MODELLING STUDIES TO RESULT IN LARGE ENERGY SAVINGS BY SOLAR MANAGEMENT, PARTICULARLY IN BUILDINGS DOMINATED BY THEIR COOLING LOAD. THE PLANNED THIN FILM APPROACH WOULD DIFFER FROM CURRENT PHOTOCHROMIC TECHNOLOGIES WHICH ARE GENERALLY SILVER-BASED. CURRENT TECHNOLOGIES ARE NOT EASILY ADAPTED TO ARCHITECTURAL GLASS AND REQUIRE BULK GLASS OR ENVIRONMENTALLY SENSITIVE POLYMER HOST MATERIALS. THE COATINGS WILL BE DERIVED FROM INORGANIC TRANSITION METAL OXIDES, AND ARE THUS EXPECTED TO BE ECONOMICAL IN MATERIALS AND PREPARATION, ROBUST, AND NOT SUBJECT TO ENVIRONMENTAL DEGRADATION. THE OBJECTIVE OF PHASE I IS TO DEMONSTRATE A NEW HIGHLY ACTIVE PHOTOCHROMIC THIN FILM EMPLOYING A NOVEL MEANS OF SENSITIZATION OF THE METAL OXIDE PHOTOCOLORATION PROCESS. THE THIN FILMS MAY BE PREPARED BY VAPOR DEPOSITION (TO BE INVESTIGATED IN PHASE I) OR BY THERMAL DECOMPOSITION OF APPROPRIATE PRECURSORS, COMPATIBLE WITH FLOAT GLASS PLANT OPERATIONS. SUCCESSFUL COMPLETION OF THE PROJECT WILL YIELD A 6 IN. SQUARE SAMPLE OF THE NEW MATERIAL AND PRELIMINARY PERFORMANCE AND LIFE TESTING RESULTS. THIS WILL FORM A BASIS OF A MORE EXTENSIVE PHASE II PROJECT IN WHICH THE COMPOSITION AND PROCESSING ARE OPTIMIZED, AND IN WHICH THE LONG TERM ENVIRONMENTAL STABILITY OF THE MATERIALS IS CHARACTERIZED AND IMPROVED.