Oxford University scientists have made a new discovery that could make it possible to create pixels just a few hundred nanometres across. This discovery could make it possible for the creation of extremely high-resolution, yet low-energy, flexible displays which are ultra thin. The use of these nano pixel displays would range from applications to do with ‘smart’ glasses and foldable screens to artificial retinas.
The team of scientists explored the link between the electrical and optical properties of phase change materials. If you don’t know, (I didn’t) a phase changing material is one, which can change from an amorphous to a crystalline state.
The scientists found that by sandwiching a seven nanometre thick layer of a phase change material (alloy Ge2Sb2Te5) Germanium-Antimony-Tellurium (GST) in-between two layers of a transparent electrode, they were able to run a tiny current to ‘draw’ images within the sandwiched material.
The team created still images initially with an atomic force microscope, but they continued to demonstrate that such tiny ‘stacks’ of material could be turned into prototype pixel-like devices. These ‘nano-pixels’ are just 300 by 300 nanometres in size, and can be electrically switched ‘on and off’, thereby creating the coloured dots, which would form the foundation of extremely high-resolution display technologies.
The work is still in its infancy, but upon realising its potential, the Oxford team have filed a patent on the discovery with the help of Oxford University’s technology commercialisation company, Isis Innovation. Isis is now in discussions with firms and investors who are interested in assessing the technology.
Professor Harish Bhaskaran of Oxford University’s Department of Materials, who led the research said, ‘We didn’t set out to invent a new kind of display…We were exploring the relationship between the electrical and optical properties of phase change materials and then had the idea of creating this GST ‘sandwich’ made up of layers just a few nanometres thick. We found that not only were we able to create images in the stack but to our surprise, thinner layers of GST actually gave us better contrast. We also discovered that altering the size of the bottom electrode layer enabled us to change the colour of the image…Because the layers that make up our devices can be deposited as thin films they can be incorporated into very thin flexible materials – we have 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.’
A report of the research, entitled ‘An optoelectronic framework enabled by low-dimensional phase change films’, is published in the journal Nature.
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