Graphene Touch Screen - Will the Future Smartphones Become Foldable?

Ever broken the touchscreen of your smartphone when falling on the floor or sitting on it? This is caused by the brittle OLED displayer and the glass layer protecting it. What if you can fold the displayer and remove that glass layer? This article will discuss speciality of graphene and the working principle of graphene touchscreen as well as its benefits.

What is Graphene?
Graphene is an allotrope of carbon which consists of a single layer of carbon atoms hybridised into sp2 form. They arrange in a hexagonal lattice. Since each carbon atom forms only 3 bonds to nearby carbon atoms, there is a delocalised electron on each carbon atom. It is as thin as an atom, making graphene extremely flexible. Graphene has an extremely low electrical resistance of 10-6 £[¡Pcm and high electron mobility of 15000 cm2/V¡Ps. Graphene is almost colourless as well, making it a perfect material for making different kind of electronic components and transistors.


Graphene Smartphone Touchscreen - How Does it Work?
The screen consists mainly of 4 components: the cathode connected to the graphene conducting layer, the organic light-emitting layer and the substrate. The graphene layer serves the function of holding charges on its surface. When the screen is touched, the charges flow out from the surface to the user. The screen then registers a voltage drop and locates the point of touching. Unlike the conventional smartphone touchscreen, the graphene replaces the indium tin oxide layer which can also conduct and hold charges on its surface. Sandwiching with 2 silver nanowire layers can increase the functionality of the screen through enhancing electrical conductivity. However, the indium tin oxide layer is so brittle that a hard glass protection layer is served as the substrate on top of the touchscreen. This makes the touchscreen of smartphone so inflexible. Since graphene is so strong and not brittle, a soft membrane can be used as the substrate. Therefore, graphene display is foldable and flexible.


What's the Advantage?
The most obvious advantage is the increased flexibility of the touchscreen. There is no need of a hard and unfoldable glass to protect any brittle component. Foldable display with plastic protection layer can be made. Also, the cost can be reduced as the indium tin oxide is costly because of the limited supply of indium metal while the production of graphene is low-cost and straightforward.