Scientists Break Kirchhoff’s Law of Thermal Radiation, Paving the Way for More Efficient Energy Systems
Researchers have achieved a major breakthrough in the field of thermal radiation by developing a device that can disrupt the traditional relationship between absorption and emission efficiencies in an object. This accomplishment challenges Kirchhoff’s law of thermal radiation, which has been in place for over 150 years.
Kirchhoff’s law states that an object’s ability to absorb and emit energy is equal at each wavelength and angle of incidence. However, the newly developed device can violate this principle, opening up new possibilities for sustainable energy harvesting systems and certain types of camouflage technology.
The breakthrough was made in the lab of Harry Atwater, the Howard Hughes Professor of Applied Physics and Materials Science. The device created by his team breaks the typically tight connection between absorbed and emitted efficiencies of an object. This is the first experimental proof that Kirchhoff’s law can be broken.
Atwater explains, “Kirchhoff’s law has been upheld for more than 150 years, and while theoretical proposals for its violation have been advanced before, this is the first experimental proof that this law can be broken.”
The implications of this breakthrough are far-reaching. In terms of energy harvesting systems, the device has the potential to enhance the efficiency of objects like photovoltaic panels. By decoupling the absorbed and emitted radiation, more energy can be converted and utilized rather than being lost as heat. This could lead to higher energy conversion efficiencies.
The device itself combines a material with a strong magnetic-field response and a patterned structure that enhances absorption and emission in infrared wavelengths. By placing the device in a moderate magnetic field and heating it above room temperature, researchers were able to directly compare the emissive efficiency to the absorptive efficiency.
The significance of this achievement is underscored by the publication of the research paper titled “Direct Observation of Kirchhoff Thermal Radiation Law Violation” in the prestigious journal Nature Photonics. The paper provides a comprehensive analysis of the experimental evidence and its implications.
Co-authored by Komron J. Shayegan, Souvik Biswas, Bo Zhao, Shanhui Fan, and Harry A. Atwater, the research was conducted with funding from the Defense Advanced Research Projects Agency.
The discovery has the potential to revolutionize various fields that rely on thermal radiation, particularly in the development of more effective energy-harvesting systems and advanced camouflage technologies. As scientists continue to explore the possibilities brought about by breaking Kirchhoff’s law, the future of energy absorption and emission looks brighter than ever.
Reference: “Direct observation of the violation of Kirchhoff’s law of thermal radiation” by Komron J. Shayegan, Souvik Biswas, Bo Zhao, Shanhui Fan, and Harry A. Atwater, 24 July 2023, Nature Photonics.
DOI: 10.1038/s41566-023-01261-6