Materials and methods for passive radiative cooling
AssigneeThe Trustees of Columbia University in the City of New York
InventorsJyotirmoy Mandal, Yuan Yang, Yijun Chen
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Abstract
A coating including a relatively thin visible-absorptive layer atop a relatively thick non-absorptive, solar-scattering underlayer. The thin top layer enables efficient absorption of appropriate visible wavelengths to show specific colors, and minimizes absorption in the infrared radiation in sunlight due to its relatively small thickness. Meanwhile, the bottom layer maximizes the backscattering of infrared light without absorption to reduce solar heating.
Claims20
A coating for use on a surface, the coating comprising:
- a colorant layer configured to selectively absorb one or more wavelengths of visible light, the colorant layer comprising one or more dyes, one or more pigments, one or more polymer binders, or combinations thereof;
- and
- a scattering layer disposed beneath and separate from the colorant layer, the scattering layer configured to backscatter solar wavelengths of near infrared light and short-wavelength infrared light;
- wherein the scattering layer has a thickness between about 1× greater and about 100× greater than that of the colorant layer.
A method for coating a surface, comprising:
- applying a first material comprising either at least one polymer and at least one liquid or a mixture comprising titanium dioxide, a polymer binder, and a liquid to the surface to form a scattering layer having an RNSWIR greater than about 0.5;
- allowing the liquid in the scattering layer to evaporate;
- and
- applying a second material comprising at least one of a dye, pigment, polymer binder, or a combination thereof to the scattering layer to form a colorant layer.
A kit for coating a surface, comprising:
- a first material comprising either at least one polymer and at least one a liquid or a mixture comprising titanium dioxide, a polymer binder, and a liquid;
- and
- wherein the first solution is configured to form a scattering layer on the surface, and the scattering layer is configured to backscatter solar wavelengths of near infrared light and short-wavelength infrared light and having an RNSWIR greater than about 0.5;
- a second solution comprising at least one of a dye, pigment, polymer binder, or a combination thereof;
- and
- wherein the second solution is adapted to form a colorant layer on top of the scattering layer, the colorant layer is configured to selectively absorb one or more wavelengths of visible light.
Dependencies are inferred from the claim text.