New possibilities in the field of solar energy — as well as in thermal energy recycling — have been opened up as the result of the development of a new way of improving the ability of nanoscale microchip components to trap and absorb light.
This nanoscale microchip component — referred to as a “multilayered waveguide taper array” — allows for a great improvement of current chips, as it slows and ultimately absorbs “each frequency of light at different places vertically to catch a rainbow of wavelengths, or broadband light.”
“We previously predicted the multilayered waveguide tapers would more efficiently absorb light, and now we’ve proved it with these experiments,” states lead researcher Qiaoqiang Gan, PhD, the University at Buffalo assistant professor of electrical engineering. “This advancement could prove invaluable for thin-film solar technology, as well as recycling waste thermal energy that is a byproduct of industry and everyday electronic devices such as smartphones and laptops.”
These multilayered waveguide tapers are, essentially, simply alternating ultrathin layers of metal, semiconductors, and/or insulators. The tapers work by absorbing light in metal dielectric layer pairs (the so-called hyperbolic metamaterial). When the thickness of these layers is manipulated (along with other geometric parameters), the tapers can be attuned to different, specific frequencies of energy — including visible light, near-infrared, mid-infrared, terahertz, and microwaves.
With regard to potential applications in the fields of photovoltaics and waste-heat capture, the University at Buffalo provides this:
It could also improve thin-film photovoltaic cells, which are a promising because they are less expensive and more flexible that traditional solar cells. The drawback, however, is that they don’t absorb as much light as traditional cells. Because the multilayered waveguide taper structure array can efficiently absorb the visible spectrum, as well as the infrared spectrum, it could potentially boost the amount of energy that thin-film solar cells generate.
The multilayered waveguide taper array could help recycle waste heat generated by power plants and other industrial processes, as well as electronic devices such as televisions, smartphones and laptop computers.
It could even be used as a stealth, or cloaking, material for airplanes, ships and other vehicles to avoid radar, sonar, infrared and other forms of detection.
“It could be useful as an ultra compact thermal-absorption, collection and liberation device in the mid-infrared spectrum,” says Dengxin Ji, a PhD student in Gan’s lab and first author of the paper.
“The multilayered waveguide tapers can be scaled up to tune the absorption band to a lower frequency domain and absorb microwaves efficiently,” states Haomin Song, another PhD student in Gan’s lab and the paper’s second author.
The new findings were just published March 28th in the journal Scientific Reports.