Thin metal oxide films printed at room temperature can transform display tech

Critical for applications like mobile phone screens and computer monitors, scientists have developed a transparent conductive oxide through a new printing approach.

In a new study undertaken by researchers from North Carolina State University, Pohang University of Science and Technology (POSTECH), Ulsan National Institute of Science and Technology, and the University of Waterloo came together to devise a type of metal oxide film at room temperature.

Scientists showed the new technique to print thin metal oxide films at room temperature. These films are transparent, flexible, and highly conductive, with the ability to function at high temperatures.

Liquid metals help craft thin metal oxide films

The printing method involves using liquid metals to deposit metal oxide layers onto surfaces, creating circuits that are both robust and versatile.

Michael Dickey, a professor of chemical and biomolecular engineering at NC State University told Interesting Engineering that transparency in metal oxide films is critical for some applications such as in cell phone screens and computer monitors which require electrodes.

“The electrodes are used to make your cell phone touch-sensitive, and they can also be used to control the pixels of light in a monitor or TV.  In this case, the oxide has to be transparent to let light through (from the screen to your eyes),” he said.

Alluding to the significance of the new development, the scientist told IE that the thinness of the material makes the film flexible.

“Our film is incredibly thin – only four nm.  As a result, it can be bent/folded without breaking,” said Dickey.

“Oxides have mechanical properties like glass….obviously, a thick piece of glass (like a window in your home) would break if you bent it. Ours can bend because it is thin. We think this might open up new applications for these materials (e.g. flexible electronics). We managed to put the film on a leaf, as an example.”

Surprisingly, researchers found the oxide was stable in high temperatures implying that the metal oxide films could be used at high temperatures, but it also implies that it should be very stable for long times in ambient conditions.

“In essence, it means the films are durable and may be useful for applications at high temperatures (none immediately come to mind of the latter, but you might imagine sensors or electronics that operate in extreme environments),” added Dickey.

Enabling production of transparent, flexible circuits

Despite being highly conductive and having metallic properties, these thin metal oxide films maintain a high level of transparency.

This makes them particularly valuable for applications where both conductivity and transparency are essential, such as in touch screens and display technologies.

Conventional methods to device metal oxide for electronics are time-consuming, costly, and require high temperatures.

However, the new way presents a more efficient approach that creates and deposits metal oxide films at room temperature, enabling the manufacturing of transparent, flexible circuits.

Now the team of scientists is hoping to extend this printing technology to other materials. Dickey explained that liquid metal was used to enable printing. For instance, to print aluminum oxide, one might expect to melt aluminum, requiring very high temperatures.

In the new process, the team demonstrated that if just a tiny amount of aluminum is added to gallium (a low melting point metal), it is possible to print aluminum oxide near room temperature.

“Inspired by these results, we are interested in exploring other materials using this technique and studying the properties of the resulting films,” the professor says.

The study was published earlier today [August 15, 2024] in the journal – Science .