The highlight of the day for me was the talk by Shanhui Fan of Stanford University on nanophotonics in light management for thermal and solar applications.
He discussed in brief three different concepts. He started with the role of nanophotonic structures on solar cell surfaces and within solar cell structures, to reduce reflection and increase both the short circuit current and open circuit voltage! He then went on to talk about how while our focus is on getting energy from the sun, for applications such as cooling buildings (power for air conditioners) another more feasible approach would be to exploit the properties of a sink! The vacuum that surrounds us has an average temperature of 3K,so we could sink our heat to it. This is such an innovative thought! But how do we do this? Again he showed some results. By making certain nanophotonic gratings of SiC etc. it is possible to give them strong thermal emissivity in 8-13micron range in which the atmosphere is transparent- allowing this radiation to go away into space. This could be an effective way to cool buildings, extract heat! He also presented an idea on how thermal extraction enhancement that without breaking the Stefan Bolztmann law, still manages to improves the performance than a conventional black body!
Some papers cited include:
Nature communications, vol. 4, pp. 1730, 2013
Nano letters,Vol. 13, pp. 1451, 2013
Optics express, Vol. 21, pp. 1209, 2013
Nano Letters, Vol. 13, pp. 1616, 2012.