Wavelength-Selective 3D Thermal Emitters via Imprint Lithography and Conformal Metallization
Shengkai Li, Amir Kazemi-Moridani, Yiliang Zhou, Irene Rose Howell, Rohit Kothari, Jae-Hwang Lee, and James J. Watkins
ACS Appl. Mater. Interfaces, DOI: 10.1021/acsami.7b16902
Metallic photonic crystals (MPCs) exhibit wavelength-selective thermal emission enhancements, and are promising thermal-optical devices for various applications. Here we report a scalable fabrication strategy for MPCs suitable for high temperature applications. Well-defined double-layer titanium dioxide (TiO2) woodpile structures are fabricated using a layer-by-layer soft-imprint method with TiO2 nanoparticle ink dispersions and the structures are subsequently coated with high purity, conformal gold films via reactive deposition from supercritical carbon dioxide. The resulting gold-coated woodpile structures are effective MPCs and exhibit emissivity enhancements at a selective wavelength. Gold coatings deposited using a cold-wall reactor are found to be smoother and result in a greater thermal emission enhancement compared to those deposited using a hot-wall reactor.