Directionally-Tailored Infrared Emission and/or Transmission

ABSTRACT: The primary objective of the proposed STTR is to develop a low-cost, high performance material which is capable of directionally-tailored thermal emission and/or transmission control. By combining advanced electromagnetic band structure engineering techniques with low-cost, self-assembled fabrication methods, highly tunable, narrow-band emissivity control can be achieved over the entire IR spectrum. In this proposal, we present a special class of nanoparticles, CSRs, that exhibit narrow band, highly tunable transparency and absorption modes. For this proposal, CSRs will be mixed with a nanostructured, high-temperature, low emissivity binder and applied to a variety of high-temperature, large surface area substrates using a high-speed dip coating process. The surface coating will be durable and capable of operating over a broad temperature range. In comparison to existing emissivity control methods and fabrication techniques, the self-assembled CSR coating has the potential advantages of being simple, inexpensive, flexible, and robust. The resonance modes of the CSRs are independent of the large-scale structure, and therefore, weakly influenced by structural disorder. The CSRs present an attractive degree of freedom in design which may facilitate multi-band operation. Additionally, the high disorder tolerance of the CSR makes it an ideal candidate metamolecular unit cell for many other self-assembled photonic structures. BENEFIT: The development of surface coatings and/or patterning for control of surface emissivity will remain an elusive goal for both the DOD and the private sector as long as expensive, laboratory-scale processes are the focus of funded research. Although the control of nanoscale features is achievable with these processes, unit area cost will remain the largest impediment to implementation. This proposal offers a novel solution using a self-assembled, metamaterial approach to emissivity control with cost and manufacturability as primary objectives. This proposal offers a novel solution using a self-assembled, metamaterial approach to emissivity control with cost and manufacturability as primary objectives. We foresee the manufacture and distribution of this surface coating extending well beyond the application described in the scope of this program. Such a coating could find use in medicine, power generation, consumer electronics, automotive, construction, aerospace, and equipment manufacturing; and many other industries that could benefit from low-cost, directional thermal or photonic control. Potential commercial applications of the proposed concept include thermal management for space vehicles (for defense and private-sector applications), thermophotovoltaic power generation, and increased-efficiency solar power generation. Photonics applications include efficient photonic waveguides, nanolasers, slow-light filters and sensors. When combined with emergent and highly capable nanoscale manufacturing technologies such as dip-pen nanolithography (DPN), high-volume and low-cost photonic circuits could be directly applied to conventional materials for integration into electronic assemblies. Similarly, the proposed technology could be used to develop low-cost sensors for biological, chemical and photonic applications in medicine, defense, and consumer electronics. The proposed dip coating / spin coating application process could be widely applied to a variety of substrates, and by expanding the potential binder materials to include polymers and cellulosic material, the list of commercial applications for passive and active CSR technologies can include low-cost, flexible (even paper-based) displays, conformal antennas, imaging devices, AR coatings, sensors, and filters.