Systems and methods for radiative cooling and heating are provided. For example, systems for radiative cooling can include a top layer including one or more polymers, where the top layer has high emissivity in at least a portion of the thermal spectrum and an electromagnetic extinction coefficient of approximately zero, absorptivity of approximately zero, and high transmittance in at least a portion of the solar spectrum, and further include a reflective layer including one or more metals, where the reflective layer has high reflectivity in at least a portion of the solar spectrum.

Systems and methods for radiative cooling and heating are provided. For example, systems for radiative cooling can include a top layer including one or more polymers, where the top layer has high emissivity in at least a portion of the thermal spectrum and an electromagnetic extinction coefficient of approximately zero, absorptivity of approximately zero, and high transmittance in at least a portion of the solar spectrum, and further include a reflective layer including one or more metals, where the reflective layer has high reflectivity in at least a portion of the solar spectrum.

A selectively-absorbing material includes a silicone polymer and transition-metal oxide nanoparticles dispersed therein. Each of the transition-metal oxide nanoparticles includes manganese. A solar receiver includes (i) a metal substrate including an etched surface having a microroughness between 0.05 micrometers and two micrometers; (ii) a polymer matrix disposed on the etched surface; and (iii) transition-metal oxide nanoparticles dispersed within the polymer matrix. A method for producing transition-metal oxide nanoparticles includes recrystallizing a plurality of two-element nanoparticles at a temperature between 300 and 700° C. The plurality of two-element nanoparticles includes at least two of (i) copper oxide nanoparticles, (ii) manganese oxide nanoparticles, and (iii) iron oxide nanoparticles. A method for fabricating a selective-absorber includes etching a top surface of a metal substrate; depositing a polymer-matrix composite on the etched top surface; and interdiffusing the polymer-matrix composite and the metal substrate. The polymer-matrix composite includes transition-metal oxide nanoparticles dispersed therein.

A solar absorber coating for a receiver element of a solar thermal or thermodynamic system. An additional aspect is a receiver for solar thermal or thermodynamic systems comprising a coating. The receiver may be an evacuated receiver pipe or a non-evacuated or air-operating receiver pipe.

A solar absorber coating for a receiver element of a solar thermal or thermodynamic system. An additional aspect is a receiver for solar thermal or thermodynamic systems comprising a coating. The receiver may be an evacuated receiver pipe or a non-evacuated or air-operating receiver pipe.

A solar thermophotovoltaic system has a heat exchanger containing a heat exchange fluid, and a thin-film integrated spectrally-selective plasmonic absorber emitter (ISSAE) in direct contact with an outer surface of the heat exchanger, the ISSAE including an ultra-thin non-shiny metal layer that is strongly absorbing in a solar spectral range and strongly reflective in an infrared spectral range. The metal layer has an inner surface in direct contact with an outer surface of the heat exchanger. A photovoltaic cell support structure with an inner surface in a concentric configuration partially surrounds the ISSAE; and an airgap separates the support structure and the outer surface of the metal layer. Photovoltaic cells are arranged on a portion of the inner surface of the support structure to receive emissions from the ISSAE, and a solar energy collector/concentrator allows solar radiation to impinge a portion of the metal layer.

A solar thermophotovoltaic system has a heat exchanger containing a heat exchange fluid, and a thin-film integrated spectrally-selective plasmonic absorber emitter (ISSAE) in direct contact with an outer surface of the heat exchanger, the ISSAE including an ultra-thin non-shiny metal layer that is strongly absorbing in a solar spectral range and strongly reflective in an infrared spectral range. The metal layer has an inner surface in direct contact with an outer surface of the heat exchanger. A photovoltaic cell support structure with an inner surface in a concentric configuration partially surrounds the ISSAE; and an airgap separates the support structure and the outer surface of the metal layer. Photovoltaic cells are arranged on a portion of the inner surface of the support structure to receive emissions from the ISSAE, and a solar energy collector/concentrator allows solar radiation to impinge a portion of the metal layer.

Selective receiver coatings provide high performance for concentrated solar power applications. The solar selective coating provides high solar absorptivity (90% or greater) with low IR emissivity (0.1 or less) while maintaining stability at temperatures greater than 700° C. The coating comprises a composite of a mesoporous photonic matrix with a conformal optical coating. One example composite coating includes a mesoporous photonic coating comprising a plurality of particles having sizes between 100 nm and 2000 nm, and a conformal optical coating formed by Atomic Layer Deposition (ALD) that infiltrates the mesoporous structure of the photonic coating and comprises metal nanoparticles and an amorphous dielectric matrix.

Selective receiver coatings provide high performance for concentrated solar power applications. The solar selective coating provides high solar absorptivity (90% or greater) with low IR emissivity (0.1 or less) while maintaining stability at temperatures greater than 700° C. The coating comprises a composite of a mesoporous photonic matrix with a conformal optical coating. One example composite coating includes a mesoporous photonic coating comprising a plurality of particles having sizes between 100 nm and 2000 nm, and a conformal optical coating formed by Atomic Layer Deposition (ALD) that infiltrates the mesoporous structure of the photonic coating and comprises metal nanoparticles and an amorphous dielectric matrix.

A material may be included in a cooling film or cooling panel to achieve cooling even under direct solar irradiation. The material includes one or more constituent materials and an outer surface configured to interact thermally with the atmosphere and with solar radiation. The material exhibits an emissivity of at least 0.8 in spectral range of 5 μm to 15 μm, an ultraviolet reflectivity of at least 0.5 in the spectral range of 275 nm to 375 nm, an ultraviolet absorptivity of at least 0.75 in the spectral range of 275 nm to 375 nm, or a combination thereof. A cooling film, or cooling panel, may be affixed to an exterior surface of a vehicle, structure, or system to provide cooling even under direct solar irradiance.