One of the major challenges in efficiently harvesting energy in the solar spectrum has been the development of a broadband device that will rectify from the infrared (IR) through the visible portion of the spectrum ~ 1015 Hz. This spectrum comprises the largest and the most energetic portion of the solar energy spectrum. Currently, silicon based energy conversion devices (photovoltaic) are narrow band devices, limiting the collection to the lower energy portion of the spectrum (red and some yellow). Because of the inherent band gap, these cells have a maximum efficiency of around 41%.
[Single Element Solar Cell] Tests have shown that the single element solar cell can absorb wave lengths much higher in the solar spectrum possibly even into the green and blue areas; this would be a milestone in solar technology. The ability to reach into the higher spectrums allows for a dramatic increase in the energy that the cells will be able to ultimately produce
[Conventional Solar Cell] Current solar cells operate in the red and lower yellow portions of the visible solar spectrum. Although improvements in efficiencies are being made, the technology currently being used has limitations on the output.
One of the most important and critical aspects for harvesting solar energy is the ability to achieve optical rectification into the visible portion of the spectrum. With current rectification devices the fastest frequency response is limited to the IR.
We have developed a new paradigm for optical rectification and have demonstrated both theoretically and experimentally the feasibility for a long sought practical rectification device that operates in the visible portion of the electromagnetic spectrum. The electromagnetic spectrum consists of the entire range of frequencies and wavelengths at which electromagnetic waves can travel and organizes energy types by wavelength and frequency.
The single element solar cell can absorb wave lengths much more energetic in the solar spectrum, that is the green and possibly the blue areas; this would be a milestone in solar technology as the ability to reach into this region allows for a dramatic increase in energy output.