From photovoltaics with startling solar cell efficiency to attosecond control of electrons, topics in the last plenary session for CLEO:2016 deftly blended both research and application. Awards presentations from IEEE, IEEE Photonics Society and The Optical Society rounded out the session. View award recipients on the CLEO website.
If you did not have a chance to see the plenary presentation, or want to revisit it, the recorded presentation will be available on the CLEO website
Record Efficiencies in Solar Cell Technology Suggest a Bright Future
Eike Weber, Director of the Fraunhofer Institute for Solar Energy, gave the first presentation titled, "Harvesting Solar Energy with Highest Conversion Efficiencies: Materials Challenges of Record Multijunction Solar Cells."
Weber focused his talk on photovoltaics with efficiencies far beyond the 15-25% of mainstream, crystalline silicon devices already in — or rather, on — so many homes today. In the lab, Fraunhofer researchers have demonstrated the world record in solar cell efficiency at 46.1% using multijunction structures.
By combining multiple materials, multijunction structures provide absorption across a wider spectrum than is available to silicon, or any other single material for that matter. However, compound semiconductors rely on careful choices of material combinations. Without proper (defect-free) matching of lattices, through which the cherished light generated charge carriers travel, recombination of the carriers would be detrimental.
Weber credits the ability to fabricate compound structures so successfully to the development of two vital technologies: epitaxial liftoff and wafer bonding. Using these methods to unite current-matched layers of III-V semiconductor materials, 3- and 4-junction solar cells are closer to 50% efficiency than ever before.
Weber didn't completely ignore crystalline silicon solar cells, demonstrating improvement in these structures as well by aluminum bonding to trap light and increase current values, announcing an upcoming publication reporting better than 30% efficiency for the more mainstream-like cell.
On the Potential of Managing Electron Behavior in Complex Systems
From the Max Planck Institute in Germany, Ferenc Krausz closed out the plenary session with his presentation, "Electrons in Real Time: Tracking and Controlling Motions at the Picometer-Attosecond Scale."
Krausz's discussion began by describing many of the key physical differences that arise in attosecond control of electrons. Namely, this is a regime in which the control takes places faster than a single cycle of the driving optical field.
Krausz also addressed why we would need such colossal temporal magnification. "The more delicate the details are by which we can follow nature.[...] the richer and longer lasting will the gains be that we are able to draw from this perception," said Krausz, quoting Max Planck before addressing just a few of the many possible applications for this new regime of probing resolution.
In physics, these are the resolutions necessary for answering fundamental questions, such as whether the time dependent Schrodinger equation works well for multiple electrons and correlated systems. In biology and medicine, understanding — and even managing — electron behavior in complex systems like proteins has revolutionary potential.
Posted: 9 June 2016 by
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