A new discovery will make it possible to create pixels just a few hundred nanometres across that could pave the way for extremely high-resolution and low-energy thin, flexible displays for applications such as 'smart' glasses, synthetic retinas, and foldable screens.
They look like works of art or poster prints but there is more to these images than meets the naked eye – as each of them is smaller than the width of a human hair.
Scientists, including a team at the University of Exeter, created them using a new imaging technique which could pave the way to ultra-thin flexible displays.
A tiny current was used to "draw" the pictures within an optical sandwich containing a "phase changing" material that can switch from a flowing to a crystalline state.
Professor David Wright, from the University of Exeter which worked with scientists at Oxford University, said that the team found that by sandwiching a seven nanometre thick layer of phase change material (GST), between two layers of transparent electrode they could use a small current to draw images within the sandwich stack.
Professor Wright said: "Along with many other researchers around the world we have been looking into the use of these GST materials for memory applications for many years".
"But no one before thought of combining their electrical and optical functionality to provide entirely new kinds of non-volatile, high-resolution, electronic colour displays - so our work is a real breakthrough".
The system relies on "nano-pixels" just 300 nanometres across that can be electrically turned on or off to create the mosaic of coloured dots that make up the images.
Professor Harish Bhaskaran, formerly of Exeter and now part of Oxford University's Department of Materials and who led the research, said: "Because the layers that make up our devices can be deposited as thin films they can be incorporated into very thin flexible materials.
"We already demonstrated that the technique works on flexible Mylar sheets around 200 nanometres thick. This makes them potentially useful for 'smart' glasses, foldable screens, windshield displays, and even synthetic retinas that mimic the abilities of photoreceptor cells in the human eye."
The scientists have filed a patent on the invention with the help of the university's technology commercialisation company, Isis Innovation .
A description of the technology appears in the journal Nature.
Dr Peiman Hosseini, from Oxford University's Department of Materials, said: "We can tune our prototype 'pixels' to create any colour we want – including the primary colours needed for a display.
"One of the advantages of our design is that, unlike most conventional LCD screens, there would be no need to constantly refresh all pixels. You would only have to refresh those pixels that actually change. This means that any display based on this technology would have extremely low energy consumption."
