The LLNL Materials Engineering Division research team has been experimenting with nanostructured metals that are designed to have low reflectivity and high absorption of visible and infrared light.
The experiment involves working with these so-called black metals which are not classic metals but rather a sort of extension of the black silicon concept. When silicon is treated in a certain way, such as being roughened at the nanoscale level, it traps light by multiple reflections, increasing its solar absorption. This gives the silicon a black surface that’s able to better trap the full sun’s wavelength spectrum.
Quite similarly black metals are developed by random nanostructuring as the team states, either in gold or silver, without any guarantee of full solar absorption. The research team led by LLNL engineer Tiziana Bond, has developed a method to improve and control absorption efficiency and turn the metals as black as they want to. This is turn facilitates the absorption of a higher quantity of solar wavelengths. This technology can possibly be used in PV development.
"Our article was picked for the cover story of Applied Physics Letters because it represents cutting-edge work in the area of plasmonics, the broadband operation obtained with a clear design and its implication for the photovoltaic yield," Bond said.