Diamond-like carbon based low-emissive coatings

A novel low-emissive (low-E) coating based on plasma enhanced chemical vapor deposited hydrogenated diamond-like amorphous carbon (DLC) films has been developed. The coating is a three-layer structure comprised of a nano-thin Ag layer sandwiched between DLC layers. The tunable optical properties that the DLC layers afford make it extremely appealing for large-scale, low-cost manufacturing of low-E coatings. We have shown that the refractive index of DLC films can be precisely tuned between 1.55 and 2.15 at a wavelength of 550 nm, while the optical gap can be tuned between 1.7 and 4.0 eV. The tunable optical properties allow greater flexibility and provide an additional parameter for optimization of low-E coatings. The tunability also allows for simple fabrication of multi-layer or graded-layer low-E coatings. Initial results of the DLC based low-E coating have a mid-IR reflectance of approximately 95% and a transmittance of approximately 70% over the visible frequencies.

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