New coating may lead to waterproof cell phones

WASHINGTON: Scientists have created new barrier films that can protect electronics in very harsh environments - even when you submerge your cell phone in salt water for months.

Researchers at the Georgia Institute of Technology have developed a new way to produce better films using atomic layer deposition.

High-end barrier films that safeguard a cell phone's high-tech organic light-emitting diode (OLED) display from every whiff of oxygen or molecule of water vapour require higher performance transparent materials such as metal oxides.

Existing methods for manufacturing these high-performance barriers are not perfect. Due to the way they're made, they often have small defects, resulting in tiny holes that let in water or oxygen.

Samuel Graham and his colleagues produced better barrier films using atomic layer deposition.

"By creating such barrier films, we are able to extend the lifetime and reliability of electronic devices," Graham said.

The new coatings can be used for electronics such as implantable biomedical devices, light-emitting diodes (LED) used in solid-state lighting and displays, solar cells, and organic electrochromic windows, which go from opaque to clear when a voltage is applied.

Barrier films will play a large role in the development of many future electronic devices made with organic materials, Graham added.

With atomic layer deposition, the researchers can make thin, even films that have minimal defects.

In this process, the researchers surround a substrate with a gas containing a particular metal atom like aluminum. The molecules of the gas attach themselves onto the substrate, forming a single layer of atoms.

Next, excess gas is removed from the chamber and another gas is introduced that then oxidises the metal, creating a metal oxide that's impervious to air or water.

The process is repeated to reach the desired thickness, which is only about 10 nanometres. In contrast, films made with more conventional techniques are tens to hundreds of times thicker.

The research will be presented at American Vacuum Society's 60th International Symposium and Exhibition in California.