New smartphone coating to make reading in sunlight easier

New York: Running to the shade to look at your phone and read a message may soon become a thing of the past as researchers have developed a new anti-reflection film that can improve sunlight visibility of screens on mobile phones and tablets.

The new anti-reflection coating, described in the journal Optica, is inspired by the nanostructures found on moth eyes. 

The anti-reflection film exhibits a surface reflection of just .23 per cent, much lower than the iPhone`s surface reflection of 4.4 per cent, for example, the researchers said.

Reflection is the major reason it is difficult to read a phone screen in bright sunlight, as the strong light reflecting off the screen`s surface washes out the display.

"Using our flexible anti-reflection film on smartphones and tablets will make the screen bright and sharp, even when viewed outside," said lead researcher Shin-Tson Wu of the College of Optics and Photonics, University of Central Florida in the US.

"In addition to exhibiting low reflection, our nature-inspired film is also scratch resistant and self-cleaning, which would protect touch screens from dust and fingerprints," Wu added.

The new film contains tiny uniform dimples, each about 100 nanometres in diameter. 

Many of today`s smartphones use a sensor to detect bright ambient light and then boost the screen`s brightness level enough to overcome the strong surface reflection. 

Although this type of adaptive brightness control can help improve readability, it also drains battery power. Other methods for solving the sunlight visibility problem have proved difficult to implement.

Looking for a simpler approach to improve screen readability outside, the researchers turned to nature. 

The eyes of moths are covered with a pattern of anti-reflective nanostructures that allow moths to see in the dark and prevent eye reflections that might be seen by predators.

Because other research groups have experimented with using moth-eye-like nanostructures to reduce the sunlight reflected off the surface of solar cells, Wu and his team thought the same technique might also work on mobile screens.

The researchers developed a fabrication technique that uses self-assembled nanospheres to form a precise template that can be used to create the moth eye-like structure on a coating.

The simplicity and precision of this process allowed fabrication of the intricate structure in a film large enough to apply to a mobile screen, the researchers said.