SBIR-STTR Award

SAGE Electrochromics, Inc. proposes to evaluate the feasibility of replacing the indium doped tin oxide (ITO) transparent conductor TC with a thin-film Ag based stack having greatly reduced costs, enhanced performance and improved durability for electrochromic (EC) windows. This new system draws upon low-emissivity technology developed in the architectural glass coating industry to maximize photopic transparency while reflecting infrared energy. These antireflecting layers are concurrently and uniquely utilized as a device electrode, distributing the uniform current required for electrochromism to occur. The goals of this effort are to: (1) reduce the costs of the TC by a order of magnitude, (2) achieve a neutral device color by tuning reflection, and (3) enhance unpackaged moisture resistance and durability by developing a low permeability capping layer with good abrasion resistance. The resulting functional EC device will have greatly improved performance at a fraction of current costs. To accomplish these objectives, we will replace the ITO with a layer of silver dereflected by transparent oxide layers. Electrical connections for biasing the device will be made to the Ag. The electrode stack will be topped by a thin-film moisture barrier. Commercial applications:Electrochromic glazings will have a tremendous impact on the architectural glass industry by allowing building occupants and owners to electronically control the shading of their window glass, anywhere from clear to deeply tinted. This dynamic solar control offers significant energy saving and comfort benefits to the end user. This proposed research will open the possibility for EC windows to be price competitive with existing static solar control windows with mechanical blind systems, enabling broad market penetration and giving the U.S. an advantage in capturing global architectural glass markets, which are projected to exceed $5 billion dollars. EC glazings will also find application in transportation windows (for safety and comfort) as well as a number of speciality applications.

In this Phase 2 program, SAGE Electrochromics, Inc. will leverage its successful Phase 1 feasibility study to replace the indium doped tin oxide (ITO) transparent conductor (TC) with a dereflected silver-based thin-film stack. Significant cost savings achieved by replacing the ITO will enhance the competitiveness of electrochromic (EC) windows in the global marketplace. Other benefits include the ability to tune the reflected color and maximize the photopic transparency by altering the materials properties and varying layer thicknesses. The outermost layer of the stack, the low permeability capping layer, improves yields during processing by retarding the ingress of moisture and contaminants. Phase 2 goals are to: (1) assure the durability of TC materials and the EC device by optimizing deposition parameters and then conducting accelerated and direct exposure testing under a variety of simulated and actual environmental stresses; (2) optimize the device optical properties by first modeling the performance of the TC stack and then fabricating composite structures and complete devices for spectral characterizations; and (3) insure that EC devices with the new structure can be manufactured at low cost by building prototypes, assessing processing problems, and instituting corrective measures that will facilitate scale-up in the commercialization phase. COMMERCIAL APPLICATIONS: Electrochromic glazings will have a tremendous impact on the architectural glass industry by allowing building occupants and owners to electronically control the shading of their window glass, anywhere from clear to darkly tinted. This dynamic solar control offers significant energy saving and comfort benefits. The proposed research will open the possibility for EC windows to be price-competitive with existing static solar control windows with mechanical blind systems, enabling broad market penetration and giving the U.S. an advantage in capturing global architectural glass markets, which are projected to exceed $5 billion. EC glazings will also find application in transportation windows (for safety and comfort) as well as a number of speciality applications