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Journal Article
Solution-Processed Phase-Change VO2 Metamaterials from Colloidal Vanadium Oxide (VOx) Nanocrystals
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- Authors
- Taejong Paik, Sung-Hoon Hong, E. Ashley Gaulding, Humeyra Caglayan, Thomas R. Gordon, Nader Engheta, Cherie R. Kagan, Christopher B. Murray
- Issue Date
- 2014-01
- Citation
- ACS Nano, v.8, no.1, pp.797-806
- ISSN
- 1936-0851
- Publisher
- American Chemical Society (ACS)
- Language
- English
- Type
- Journal Article
- Abstract
- We demonstrate thermally switchable VO2 metamaterials fabricated using solution-processable colloidal nanocrystals (NCs). Vanadium oxide (VOx) NCs are synthesized through a nonhydrolytic reaction and deposited from stable colloidal dispersions to form NC thin films. Rapid thermal annealing transforms the VOx NC thin films into monoclinic, nanocrystalline VO2 thin films that show a sharp, reversible metal-insulator phase transition. Introduction of precise concentrations of tungsten dopings into the colloidal VOx NCs enables the still sharp phase transition of the VO2 thin films to be tuned to lower temperatures as the doping level increases. We fabricate "smart", differentially doped, multilayered VO2 films to program the phase and therefore the metal-insulator behavior of constituent vertically structured layers with temperature. With increasing temperature, we tailored the optical response of multilayered films in the near-IR and IR regions from that of a strong light absorber, in a metal-insulator structure, to that of a Drude-like reflector, characteristic of a pure metallic structure. We demonstrate that nanocrystal-based nanoimprinting can be employed to pattern multilayered subwavelength nanostructures, such as three-dimensional VO2 nanopillar arrays, that exhibit plasmonic dipolar responses tunable with a temperature change. © 2013 American Chemical Society.
- KSP Keywords
- Colloidal dispersions, Colloidal nanocrystal, Colloidal vanadium oxide, Increasing temperature, Light absorber, Lower temperature, Metallic structure, Multilayered films, Phase change, Rapid thermal annealing(RTA), Solution-processed