Moth-eye antireflective optical film comes with its own cleaning agent

Feb. 21, 2014
Cambridge, England--Researchers from the University of Cambridge, Cornell University (Ithaca, NY), CSM Instruments (Peseux, Switzerland), and the University of South Carolina (Columbia, SC) have created a self-cleaning AR moth-eye coating by incorporating a photocatalytic material in the structure.

Cambridge, England--"Moth-eye" antireflection (AR) thin-film optical coatings, which create an index gradient (and thus AR properties) using 2D periodic arrays of tapered subwavelength structures, have been created in many forms. One of the perceived problems of these coatings is that their structures can get clogged with contaminantsfingerprint oil, for exampleand thus lose their AR properties.

Now, researchers from the University of Cambridge, Cornell University (Ithaca, NY), CSM Instruments (Peseux, Switzerland), and the University of South Carolina (Columbia, SC) have created a self-cleaning AR moth-eye coating by incorporating a photocatalytic material in the structure.1 The group created a polymer moth-eye structure with a larger-than normal array period that allowed them to incorporate preformed titanium dioxide (TiO2) nanocrystals within the array.

When light falls on the photocatalytic TiO2 nanocrystals, they break down the dirt clogging the structure until all that is left is carbon dioxide and water (which evaporates off the surface). In early tests of the material, the TiO2 nanoparticles were able to break down all of the oils contained in a fingerprint within 90 minutes. The coating is capable of breaking down most of the standard hydrocarbons that clog most porous AR coatings, the researchers assert.

The coating, which can be deposited onto flexible plastic substrates, adheres to the substrate through sol-gel chemistry, resulting in a durable bond and a coating that will not flake off, say the researchers. The material is currently only suitable for outdoor applications. as it requires UV light for photocatalysis to occur; however, the researchers are planning more tests to see if the material could be adapted in future for indoor light.

Potential applications include building glass and solar cells.

REFERENCE:

1. Stefan Guldin et al., Nano Letters 2013 13 (11); doi: 10.1021/nl402832u

About the Author

John Wallace | Senior Technical Editor (1998-2022)

John Wallace was with Laser Focus World for nearly 25 years, retiring in late June 2022. He obtained a bachelor's degree in mechanical engineering and physics at Rutgers University and a master's in optical engineering at the University of Rochester. Before becoming an editor, John worked as an engineer at RCA, Exxon, Eastman Kodak, and GCA Corporation.

Sponsored Recommendations

How to Tune Servo Systems: Force Control

Oct. 23, 2024
Tuning the servo system to meet or exceed the performance specification can be a troubling task, join our webinar to learn to optimize performance.

Laser Machining: Dynamic Error Reduction via Galvo Compensation

Oct. 23, 2024
A common misconception is that high throughput implies higher speeds, but the real factor that impacts throughput is higher accelerations. Read more here!

Boost Productivity and Process Quality in High-Performance Laser Processing

Oct. 23, 2024
Read a discussion about developments in high-dynamic laser processing that improve process throughput and part quality.

Precision Automation Technologies that Minimize Laser Cut Hypotube Manufacturing Risk

Oct. 23, 2024
In this webinar, you will discover the precision automation technologies essential for manufacturing high-quality laser-cut hypotubes. Learn key processes, techniques, and best...

Voice your opinion!

To join the conversation, and become an exclusive member of Laser Focus World, create an account today!