Anti-Reflective Coating

Researchers have developed an antireflective (AR) coating that works better than anything currently available, over the entire solar spectrum and at multiple angles. Although it was initially conceived as a coating to maximize the efficiency of solar cells, the technology will have application as a coating for eyeglasses, computer monitors and smartphone displays as well.

Refractive index refers to the speed at which light travels through a specific medium. Reflections occur when light travels between materials with different refractive indices – in this case, air (with a refractive index of 1) and plastic (with a refractive index of 1.5). Teflon has the lowest index of any natural coating material at 1.3 and can be blended with other materials to cover a range of 1.3 to 1.5. So the challenge was to create a process that would bridge the gap between air and Teflon.

To do this, the researchers heated the Teflon to the point where it sent up a vapor flux. Sacrificial molecules were then added to the flux, and Teflon reformed around the molecules. The sacrificial molecules were then dissolved to form nanoscale pores, creating a graded-index Teflon film that transitions seamlessly from 1 to 1.5.

The technique is compatible with current manufacturing methods and could be scaled up relatively easily for a variety of applications.