Researchers from the Delft Technical University (the Netherlands) made a discovery that one day could lead to the emergence of a new display technology. Scientists have created the so-called graphene bubbles, which can change color when expanded and in contact with each other. Researchers say that their “physical pixels” may one day become part of new, more flexible, durable and energy efficient screens, compared to conventional LEDs.
However, experts indicate that the technology created by them is in its infancy. In itself, the production of graphene is very expensive, and here there is also a new technology. In general, it is premature to rejoice at the speedy release of displays based on new technology.
Whatever it was, scientists made their discovery when working with silicon oxide plates, which were covered with a double layer of graphene with a thickness of two carbon atoms. The plates themselves contain tiny (10 times thicker than the thickness of a human hair) holes, which are closed by a graphene layer and create a kind of air bubble. Working with these samples, scientists noted that graphene bubbles are able to change their color depending on the pressure that exists in the holes. When the pressure changes, the bubbles become either concave or elongated and at the same time refract the light passing through them, changing its color.
Technical diagram showing how graphene layers can stretch over cavities in silicon oxide plates
“In its basic form, graphene is a transparent material. It is so subtle that the light is practically not reflected from it, ”said researcher Santiago Cartamil-Bueno.
"However, we used a double layer of graphene, so the light was refracted more strongly."
When the graphene bubbles bent in and out, the light had to travel less or more than the distance to the silicon oxide substrate. This, in turn, led to changes in what part of the light spectrum was absorbed and which part was reflected back, which, in turn, was a change in color.
“Depending on the depth of the holes, you get a different level of interference. From this, changes in color are observed, ”explains Cartamil-Bueno.
The same principle is used, for example, in Qualcomm's Mirasol technology, which uses reflective membranes controlled by electrostatics. As in the case of E-Ink-displays, this technology shows a very high level of energy efficiency: as soon as an image is displayed on the screen, no additional power is required to support it. However, the feature of these displays is such that the backlight cannot be used in them. From this it turns out that it will be almost impossible to read such displays in the dark, but at the same time, in bright light they remain perfectly readable.
However, numerous difficulties stand in the way of mass use of technology of graphene-based screens. First, changes in the color of graphene bubbles were observed only under a microscope, since, recall, the production of similar graphene samples, but of larger size, will be very expensive. As a result, the “pixels” turned out so small that it would take hundreds of thousands of pixels to create even a very small image on their base. To make graphene bubbles larger also will not work - there is a possibility of their unstable behavior (they can simply burst). Secondly, researchers at Delft Technical University have not yet figured out how pure colors can be created on their basis.
“We observed different colors. Like a rainbow. However, we cannot yet create pure colors: for example, pure red or pure blue, ”explains Cartamil-Bueno.
Artistic representation of graphene pixels
The next step for scientists will be to search for effective and precise control of the variable pressure in each individual cavity. Cartamil-Bueno, that his team is considering a variant of electrostatics, that is, the principle that is used in the screens of Mirasol. The progress is already there. As is the case with Mirasol displays, the new technology will be very effective in sunlight, while graphene will make these screens very durable, flexible and light. The university is currently working on the first prototypes. Who knows, perhaps we will be able to see the first copies at the next MWC exhibition, which will be held in March of the next year.
The article is based on materials .
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