Solar Cells
FIG. 4.1 What is old is new again! While most vacuum tubes have been relegated to the dust bin of history it is possible to reinvent their kind by introducing them as nano-scale devices that interact with light and Surface Plasmon Polaritons (SPP) instead of just electrons. And just like their ancestors of old, the newfangled vacuum tubes can, in principle, rectify a sinusoidal signal to produce a DC output---electricity. Instead of just rectifying electrical signals they may be able to rectify SPP excitations---hybrid particles that are part light and part electricity! Image source: Getty Images.
The objective
Note to reader: The technology summarized in this section was presented to the US government’s Advanced Research Projects Agency for Energy (ARPA-E), and was carefully reviewed by government, university, and commercial experts. XE was awarded “ARPA-E finalist” status. Out of 3,682 high-tech companies and universities that participated only 312 organizations (less than 9%) were recognized as finalists---having ideas that could be truly disruptive. The following XE solar cell technology was among the finalists.
XE is developing a new type of solar cell based on the indirect rectification of concentrated sunlight into electricity by sunlight-induced Surface Plasmon Polaritons (SPP), field emission of the resulting plasmon electrons, and rectification into electricity by quantum tunneling. The solar cell is called a SUrface Plasmon Enhanced Rectification solar cell (SUPER cell™ ). This new type of concentrating solar cell provides an entirely new path to photovoltaics, using nano-scale vacuum tubes, with potential conversion efficiencies greater than 64%, which is the current theoretical limit for triple-junction solar cells, and up to a theoretical maximum of about 84%. The nano-structures of the SUPERcells are not limited by intrinsic material band-gaps, are not subject to severe performance degradation at high temperatures, are not extremely sensitive to ionizing radiation, and do not use rare elements that are limited in availability, like solar cells containing Indium, Gallium, Tellurium and Cadmium. The easily available materials, potential for ultra-high efficiency, and potential for scalability to extremely large production levels makes SUPER Cell™ a candidate for a low cost disruptive technology to provide sustainable clean energy to the world.