Flexible and tunable infrared emissivity material platform
View Patent ↗A material platform with controllable emissivity and fabrication methods are provided that permit the manipulation of thermal radiation detection and IR signal modulation and can be adapted to a variety of uses including infrared camouflage, thermal IR decoys, thermo-reflectance imaging and IR signal modulation. The platform is a multilayer W x V 1-x O 2 film with different W doping levels (x values) and layer thicknesses, forming a graded W-doped construct. In WVO 2 films with a total thickness <100 nm, the graded doping of W spreads the originally sharp metal-insulator phase transition (MIT) to a broad temperature range, greatly expanding the temperature window for emissivity modulation.
1 . A controllable emissivity film, comprising a composite of multiple WVO 2 thin film layers with graded W doping, each of said layers having a thickness and a dopant percentage and a total thickness of 100 nm or less, wherein said multiple film layers have progressively increasing thicknesses from a top surface to a bottom surface of said composite WVO 2 thin film.
2 . The film of claim 1 , further comprising a substrate coupled to said WVO 2 thin film.
3 . The film of claim 2 , further comprising:
removing the final graded doped WVO 2 thin film from the substrate; and
coupling the film to a mechanically flexible substrate.
4 . The film of claim 1 , wherein said multiple film layers have progressively decreasing dopant percentages from a top surface to a bottom surface of said WVO 2 thin film.
5 . The film of claim 4 , wherein said dopant percentages of said layers from the top surface to the bottom surface decrease from 3% dopant to 0% dopant per volume.
6 . The film of claim 1 , wherein said multiple film layers have progressively increasing dopant percentages from a top surface to a bottom surface of said WVO 2 thin film.
7 . The film of claim 6 , wherein said dopant percentages of said layers from the top surface to the bottom surface increase from 0% dopant to 3% dopant per volume.