Antireflection (AR) coatings have a variety of practical uses, including glare reduction in eyeglasses, computer monitors and outdoor displays on your smartphone. Researchers at the University of Penn have now developed an antireflection coating to improve existing coatings to virtually invisible transparent plastics like Plexiglas.
The approach involved focusing light on small, highly efficient plastic solar cells while reducing their loss of reflection. Their anti-reflection layer worked well over the entire spectrum of the solar energy, and in many ways when the sun crossed the sky. They needed a coating that could bear the weather outdoors for long periods of time.
Teflon Used to Create Nanoscale Pores
While making a coating that eliminates reflection at a particular wavelength or in a given direction is relatively easy, there was no coating capable to meet all their criteria. Eyeglass AR coatings, for example, are designed for the narrow visible part of the spectrum. But the solar spectrum is approximately five times the width of the visible spectrum so a solar cell system would not work well.
A new procedure to bridge the gap between Teflon and air using a sacrificial molecule to produce nanoscale pores of evaporated teflon in a recent paper, Giebink and the co- authors describe a new way to produce an index Teflon- Air film, so that light is frozen to see a smooth change from 1 to 1.5, eliminating most reflections.
The Teflon reforms the molecules by adding the sacrificial molecules to the flux. Dissolving the sacrificial molecules leaves a nanoporous film which can be classified with additional pores.