Anti-Reflective Coating
![](images/06-Anti-Reflective-Coating-A.jpg)
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.
For information: Chris Giebink, Penn State University, Electrical Engineering Department, 0121 Electrical Engineering East, University Park, PA 16802; phone: 814-865-2229; email: ncg2@psu.edu; website: https://www.psu.edu/