MIT, Masdar Institute develop more efficient solar absorber
Author: Carl Milner. License: Creative Commons, Attribution 2.0 Generic.
A more efficient solar absorber for solar thermal and other applications has been developed by researcher at Masdar Institute and the Massachusetts Institute of Technology (MIT) using plasmonics.
The team has developed a “simple and cost-effective fabrication technique” to make solar absorbers that can harness a greater share of the solar spectrum and turn it into heat, Masdar Institute said last week. The MIT-Masdar Institute researchers believe they have found the point at which the optimal levels of sunlight are absorbed with the least amount of energy escaping back into the atmosphere through radiation.
The research effort is described in a paper in the journal Advanced Optical Materials.
The fabrication technique involves patterning a solar absorber with tiny holes with diameters less than 400 nanometers at regular intervals. The holes penetrate the entire absorber and thus significantly increase the range of solar energy that can be absorbed. Nearly 90% of the wavelengths of light that reach the Earth’s surface are absorbed by the nano-hole patterned absorber.
This absorber has only two layers -- a semiconductor film and a reflective metallic layer, with a total thickness of 170 nanometers.
The next step in the research effort will be the testing of the overall solar conversion efficiency of the coating materials. The team is now working to optimise the system with alternative metals for the reflective metallic layer, such as aluminum, copper or silver, which will further reduce the costs.
The work contributes to a larger Masdar Institute-MIT research project, which is aimed at developing a solar-powered, combined electrical power plant and cooling system.