Cracking the code of unbreakable phone screens
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<p>Unbreakable phone screens might seem too good to be true, but some chemical engineers reckon they’ve cracked the secret, developing a new material that combines glass with nanocrystals to make a resilient screen that would produce high-quality images in phones, LEDs and computers.</p>
<p>The breakthrough substance could even be used to make phone screens that double as solar panels.</p>
<p>The technology revolves around <a rel="noreferrer noopener" href="https://cosmosmagazine.com/science/overcoming-atomic-level-perovskite-defects/" target="_blank">perovskites</a>: nanometre-sized crystals that have a range of exciting electrical properties, making them prime candidates for better solar cells, LEDs and touchscreens.</p>
<p>While perovskites have had a few early commercial successes, their physical properties have mostly stopped them from getting far out of the lab.</p>
<p>“The stability of perovskites is the most difficult challenge which has hindered their commercialisation,” says Professor Lianzhou Wang, a materials scientist at the University of Queensland and co-author on a paper describing the research, <a rel="noreferrer noopener" href="http://www.science.org/doi/10.1126/science.abf4460" target="_blank">published</a> in <em>Science.</em></p>
<p>Lead author Dr Jingwei Hou, also from UQ, says the material is “super sensitive to almost everything – oxygen, water, gas, temperature, and even sensitive to light.</p>
<p>“I think it’s a fantastic material, but it doesn’t really make sense if we want to use it on a solar panel, or display, if it’s sensitive to light.”</p>
<p>The researchers have overcome this sensitivity by figuring a way to encase lead-halide perovskites in glass.</p>
<p>“We created a lot of very small, nano-sized pores within the glass,” explains Hou. “That offers a very nice host material environment for the perovskite.</p>
<p>“If we just put those very small nanocrystals within the pores, they will be not only stabilised against all of the external environment…it also makes the perovskite somewhere between 100 to 1000 times more efficient.”</p>
<p>At the level of nanometres, the material resembles a chocolate chip cookie. “The perovskite nanocrystals are the chocolate chips, and the glass surrounds them,” says Hou.</p>
<p>The material is also much more durable than normal glass. “Conventional glass is so brittle [because] it’s really dense. If you zoom in and look at the molecular structure, it’s silicon, aluminium, oxygen – very densely packed atoms,” says Hou.</p>
<p>“Once you apply any pressure or any mechanical force to it, there’s no way to get it relaxed, and that’s what leads to the breakage of chemical bonds.”</p>
<p>The pores, on the other hand, allow the glass to absorb more stress.</p>
<p>“This is really a kind of platform technology,” says Hou. “The pore size can be tuned, the chemistry can be tuned. So that means it can be used to host a different type of perovskite.”</p>
<p>In the paper, the international team of researchers – who are based at the University of Leeds and the University of Cambridge in the UK, and Université Paris-Saclay in France – demonstrate several different types of “lead halide perovskite and metal-organic framework glasses”, all of which they’ve been able to create.</p>
<p>As well as their potential applications in screens and LEDs, the glasses could be used to make higher-quality X-ray images and more efficient solar panels.</p>
<p>“We’re looking at trying to combine a solar panel with a display,” says Hou.</p>
<p>“Think about mobile phones, for example – when you use it, it will become a display. When you don’t use it, put it in the sunlight, it will charge the battery. So it’s one device for two functions.”</p>
<p>Manufacture of the material is scalable, according to Hou, and the researchers are currently looking at building prototype devices with it.</p>
<p>“We’re really confident that we’ll be able to generate devices in the next stage,” says Hou.</p>
<p>“We are also looking for some industrial collaborators who are really interested in bringing this exciting material into the real world.”</p>
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<p><em>This article was originally published on <a rel="noopener" href="https://cosmosmagazine.com/technology/materials/unbreakable-phone-screens/" target="_blank">cosmosmagazine.com</a> and was written by Ellen Phiddian.</em></p>
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