tag:theconversation.com,2011:/us/topics/organic-electronics-28371/articlesOrganic electronics – The Conversation2018-09-21T11:07:54Ztag:theconversation.com,2011:article/1034872018-09-21T11:07:54Z2018-09-21T11:07:54ZSamsung’s foldable phone could soon be a reality<figure><img src="https://images.theconversation.com/files/237125/original/file-20180919-158225-4dixv4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><a class="source" href="https://news.samsung.com/us/samsung-displays-unbreakable-panel-certified-underwriters-laboratories/">Samsung</a></span></figcaption></figure><p>We rarely see a truly remarkable new technology more than once a decade. After <a href="https://theconversation.com/why-are-flexible-computer-screens-taking-so-long-to-develop-53143">years of undelivered promises</a>, such a technology looks finally set to enter the market: the flexible computer screen.</p>
<p>Imagine, a tablet display you can fold up and put in your pocket, a smart watch whose strap is the screen, or a handbag that is also a monitor and keyboard. Nokia <a href="https://www.cam.ac.uk/news/cambridge-and-nokia-introduce-new-stretchable-and-flexible-mobile-phone-concept">originally called</a> this proposed technology “Morph” back in 2008 because of the plethora of applications it would make possible. Now it looks like it will become a reality.</p>
<p>After nearly <a href="https://www.militaryaerospace.com/articles/print/volume-15/issue-10/features/technology-focus/display-technology-leaps-to-the-next-generation.html">two decades of work</a>, Samsung <a href="https://bgr.com/2018/09/05/samsung-foldable-galaxy-phone-more-design-details/">is rumoured</a> to be getting ready for the launch of the first flexible smartphone. The company’s head of mobile <a href="https://www.cnbc.com/2018/09/04/samsung-unveiling-a-foldable-smartphone-this-year.html">recently said</a> it was “time to deliver” such a phone, and that the development process for it was “nearly concluded”.</p>
<p>But perhaps more significantly, the Samsung Display division of the company <a href="https://news.samsung.com/us/samsung-displays-unbreakable-panel-certified-underwriters-laboratories/">recently said</a> it had developed an “unbreakable smartphone panel” that had passed rigorous safety testing. Even after being subjected to temperatures of 71˚C and -32˚C, and dropped from a height of 1.8 metres, the display showed no signs of damage and functioned normally. </p>
<p>This display is a flexible organic light emitting diode (OLED) panel made of an unbreakable surface with a plastic overlay window attached to it, making it simultaneously lightweight and tough as glass but a lot more robust. Manufacturers have yearned for many years to make displays with flexible, bendable properties and a paper-like feel with electronic functionality. If Samsung has truly found a way to protect a flexible OLED then it has solved a major technical challenge in removing the need for the glass screens used on most other displays today.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/237326/original/file-20180920-129859-13xw3qt.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/237326/original/file-20180920-129859-13xw3qt.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/237326/original/file-20180920-129859-13xw3qt.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/237326/original/file-20180920-129859-13xw3qt.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/237326/original/file-20180920-129859-13xw3qt.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/237326/original/file-20180920-129859-13xw3qt.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/237326/original/file-20180920-129859-13xw3qt.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Smartphone of the near future?</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-illustration/flexible-smartphone-concept-illustration-screen-layout-159538328?src=kg8nz5EEKv0q5zuQsPTtGg-1-2">Grzegorz Petrykowski/Shutterstock</a></span>
</figcaption>
</figure>
<p>Glass was originally needed to actually stop displays from bending. Old-fashioned liquid crystal displays easily distorted when bent because the molecules in the liquid inside them would become misaligned. <a href="https://www.whathifi.com/advice/what-oled-tech-benefits-best-oled-tvs-and-oled-phones">Today’s OLED screens</a> are based on a solid layer of light-emitting material that doesn’t easily distort in this way. But glass is also used to protect the organic molecules in an OLED display from being degraded by water vapour and other gases that would shorten their lifespan. Until now, encapsulating displays in flexible plastic hasn’t been enough to protect them.</p>
<p>A more advanced, <a href="https://www.androidauthority.com/quantum-dot-vs-oled-explained-659321/">better quality</a> kind of screen known as a <a href="https://www.cnet.com/news/how-quantum-dots-could-challenge-oled-for-best-tv-picture/">quantum dot light emitting diode</a> (QLED) display can also be made flexible. These use nano-crystals to produce high-quality, pure and sharp monochromatic light. They convert the backlight into the pure basic colours without the use of filters. But encapsulating QLED displays is even harder than OLEDs and so are likely to take a lot longer to turn into a flexible product.</p>
<h2>Increasing flexibility</h2>
<p>Samsung’s flexible OLED screen is likely to be have the most basic level of flexibility, with the ability to be bent and curved without distorting the display but not completely folded. The level of flexibility might be increased as the nanotechnology in the screens improves, as the nanowires used to carry electricity through the displays become <a href="https://www.nature.com/articles/srep45903">more flexible at smaller diametres</a>. </p>
<p>In the future we may eventually see rollable displays that can be rolled up like a scroll. The most advanced type of flexible screen will be one that can be folded or even crushed like a sheet of paper and still produce a seamless image. The newest and most exciting idea for creating these screens is to use <a href="https://www.nature.com/articles/s41467-017-00399-6">new “auxtetic” materials</a>, which become thicker as they are stretched rather than thinner.</p>
<p>These materials can absorb high energy impacts and are made of single molecules or crystals that can self-align once distorted. They are typically lightweight and would allow the creations of screens with hinge-like design features that can flex significantly.</p>
<p>In the meantime, appears that within a year we could be able to snuggle up in bed reading from a screen that we don’t have to worry about damaging if we fall asleep on it. I, for one, can’t wait to get my hands on this new tech.</p><img src="https://counter.theconversation.com/content/103487/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Ravi Silva does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>After two decades of work, the technical challenges of a bendable screen may have been overcome.Ravi Silva, Director, Advanced Technology Institute, University of SurreyLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1003502018-07-31T10:40:24Z2018-07-31T10:40:24ZDesigning a ‘solar tarp,’ a foldable, packable way to generate power from the sun<figure><img src="https://images.theconversation.com/files/228894/original/file-20180723-189308-v38f9n.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">What if it were a lot easier to install solar power?</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/solar-panel-technician-drill-installing-panels-345605207">zstock/Shutterstock.com</a></span></figcaption></figure><p>The energy-generating potential of solar panels – and a key limitation on their use – is a result of what they’re made of. Panels made of silicon are declining in price such that in some locations they can provide electricity that <a href="http://www.greenrhinoenergy.com/solar/market/mkt_trends.php">costs about the same as power from fossil fuels</a> like coal and natural gas. But silicon solar panels are also bulky, rigid and brittle, so they can’t be used just anywhere.</p>
<p>In many parts of the world that don’t have regular electricity, solar panels could provide <a href="http://pubs.rsc.org/en/content/articlelanding/2010/ee/b918441d">reading light after dark</a> and energy to <a href="http://www.earthisland.org/journal/index.php/elist/eListRead/in_africa_clean_energy_provides_a_route_to_clean_water/">pump drinking water</a>, help <a href="https://e360.yale.edu/features/african_lights_microgrids_are_bringing_power_to_rural_kenya">power small household or village-based businesses</a> or even serve <a href="https://www.huffingtonpost.com/entry/refugee-camp-solar-energy-azraq_us_591c6ba4e4b0ed14cddb4685">emergency shelters and refugee encampments</a>. But the mechanical fragility, heaviness and transportation difficulties of silicon solar panels suggest that silicon may not be ideal.</p>
<p><a href="https://doi.org/10.1002/adma.201302563">Building on</a> <a href="https://www.nrel.gov/pv/organic-photovoltaic-solar-cells.html">others’ work</a>, <a href="https://www.lipomigroup.org/">my research group</a> is working to <a href="https://scholar.google.com/citations?user=ADi0TFMAAAAJ&hl=en">develop flexible solar panels</a>, which would be as efficient as a silicon panel, but would be thin, lightweight and bendable. This sort of device, which we call a “<a href="https://doi.org/10.1016/j.joule.2017.12.011">solar tarp</a>,” could be spread out to the size of a room and generate electricity from the sun, and it could be balled up to be the size of a grapefruit and stuffed in a backpack as many as 1,000 times without breaking. While there has been some effort to make organic solar cells more flexible simply by <a href="https://www.photonics.com/Articles/Ultrathin_solar_cells_for_stretchable_applications/a51133">making them ultra-thin</a>, real durability requires a molecular structure that makes the solar panels stretchable and tough.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/229117/original/file-20180724-194149-1foyq8z.gif?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/229117/original/file-20180724-194149-1foyq8z.gif?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/229117/original/file-20180724-194149-1foyq8z.gif?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/229117/original/file-20180724-194149-1foyq8z.gif?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/229117/original/file-20180724-194149-1foyq8z.gif?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/229117/original/file-20180724-194149-1foyq8z.gif?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/229117/original/file-20180724-194149-1foyq8z.gif?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/229117/original/file-20180724-194149-1foyq8z.gif?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">A small piece of a prototype solar tarp.</span>
<span class="attribution"><span class="source">University of California, San Diego</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<h2>Silicon semiconductors</h2>
<p>Silicon is derived from sand, which makes it cheap. And the way its atoms pack in a solid material makes it a good semiconductor, meaning its conductivity can be switched on and off using electric fields or light. Because it’s cheap and useful, <a href="http://theconversation.com/beyond-silicon-the-search-for-new-semiconductors-55795">silicon is the basis for the microchips and circuit boards in computers</a>, mobile phones and basically all other electronics, transmitting electrical signals from one component to another. Silicon is also the key to most solar panels, because it can convert the energy from light into positive and negative charges. These charges flow to the opposite sides of a solar cell and can be used like a battery.</p>
<p>But its chemical properties also mean it can’t be turned into flexible electronics. Silicon doesn’t absorb light very efficiently. Photons might pass right through a silicon panel that’s too thin, so they have to be fairly thick – around 100 micrometers, <a href="https://www.wolframalpha.com/input/?i=100+micrometers">about the thickness of a dollar bill</a> – so that none of the light goes to waste.</p>
<h2>Next-generation semiconductors</h2>
<p>But researchers have found other semiconductors that are much better at absorbing light. One group of materials, called “<a href="http://dx.doi.org/10.1126/science.aan2301">perovskites</a>,” can be used to make solar cells that are <a href="https://www.sciencedaily.com/releases/2017/07/170725122105.htm">almost as efficient as silicon ones</a>, but with light-absorbing layers that are one-thousandth the thickness needed with silicon. As a result, researchers are working on building <a href="http://doi.org/10.1117/2.1201608.006223">perovskite solar cells that can power small unmanned aircraft</a> and other devices where reducing weight is a key factor.</p>
<p>The <a href="https://www.nobelprize.org/nobel_prizes/chemistry/laureates/2000/">2000 Nobel Prize in Chemistry</a> was awarded to the researchers who first found they could make another type of ultra-thin semiconductor, called a semiconducting polymer. This type of material is called an “organic semiconductor” because it is based on carbon, and it is called a “polymer” because it consists of long chains of organic molecules. Organic semiconductors are already used commercially, including in the <a href="https://www.tvtechnology.com/news/cta-oled-tv-vr-and-drones-pass-1b-in-revenue">billion-dollar industry</a> of <a href="https://www.cnet.com/news/what-is-oled-and-what-can-it-do-for-your-tv/">organic light-emitting diode displays</a>, better known as OLED TVs.</p>
<p>Polymer semiconductors aren’t as efficient at converting sunlight to electricity as perovskites or silicon, but they’re much more <a href="https://doi.org/10.1038/539365a">flexible and potentially extraordinarily durable</a>. Regular polymers – not the semiconducting ones – are found everywhere in daily life; they are the molecules that make up fabric, plastic and paint. Polymer semiconductors hold the potential to combine the electronic properties of materials like silicon with the physical properties of plastic.</p>
<h2>The best of both worlds: Efficiency and durability</h2>
<p>Depending on their structure, plastics have a wide range of properties – including both flexibility, as with a tarp; and rigidity, like the body panels of some automobiles. Semiconducting polymers have rigid molecular structures, and many are composed of tiny crystals. These are key to their electronic properties but tend to make them brittle, which is not a desirable attribute for either flexible or rigid items. </p>
<p>My group’s work has been focused on identifying ways to create <a href="https://doi.org/10.1016/j.joule.2017.12.011">materials with both good semiconducting properties and the durability</a> plastics are known for – whether flexible or not. This will be key to my idea of a solar tarp or blanket, but could also lead to roofing materials, outdoor floor tiles or perhaps even the surfaces of roads or parking lots. </p>
<p>This work will be key to harnessing the power of sunlight – because, after all, the sunlight that strikes the Earth in a single hour contains <a href="http://www.businessinsider.com/this-is-the-potential-of-solar-power-2015-9">more energy than all of humanity uses in a year</a>.</p><img src="https://counter.theconversation.com/content/100350/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Darren Lipomi receives funding from the Air Force Office of Scientific Research, the National Institutes of Health, and Benefunder through a gift from the B Quest Giving Fund</span></em></p>Silicon is cheap and a good semiconductor, but it’s bulky and rigid. Using organic polymers as semiconductors could yield solar panels with the physical characteristics of plastics.Darren Lipomi, Professor of Nanoengineering, University of California, San DiegoLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/953522018-05-11T10:52:15Z2018-05-11T10:52:15ZSmart windows could combine solar panels and TVs too<figure><img src="https://images.theconversation.com/files/217627/original/file-20180503-138586-5ldwyo.png?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Could this monitor and window be combined with a solar panel?</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/business-window-shop-advertising-lcd-television-1030004530">patat/Shutterstock.com</a></span></figcaption></figure><p>Imagine standing in front of a wall of windows, surveying the view. You hear someone enter the room behind you. You turn. “Welcome,” you say. “Here is the video I wanted to show you.” At the press of a button, the view vanishes and the windows transform into a high-definition TV screen.</p>
<p>No, your friend isn’t James Bond, and you aren’t the next Q. Still, even as you watch the video, your window-TV is doing as much to help avert global catastrophe as any Bond-film gadget ever did. You see, it’s also a solar panel, constantly harvesting renewable energy from the sun. The problem of climate change is not a typical movie supervillain, but it’s a trickier problem than <a href="https://en.wikipedia.org/wiki/Goldfinger_(film)">Goldfinger</a> posed. Worse, humanity’s efforts to solve it with existing technologies <a href="http://news.mit.edu/2016/carbon-tax-stop-using-fossil-fuels-0224">aren’t working fast enough</a>.</p>
<p>The heroes swooping in to the rescue could be a new technology called <a href="https://www.sigmaaldrich.com/technical-documents/articles/material-matters/organic-materials.html">organic semiconductors</a>, a new way to make materials that conduct electricity only under certain conditions. Most semiconductors in modern electronics are made of crystalline, rock-forming <a href="https://theconversation.com/beyond-silicon-the-search-for-new-semiconductors-55795">elements like silicon</a>. Organic semiconductors, by contrast, are made primarily of carbon-based molecules. They take less <a href="https://www.nrel.gov/docs/fy04osti/35489.pdf">energy to make</a> than conventional semiconductors. A conventional photovoltaic cell, for instance, can take years to produce as much energy as was required to build it; an organic photovoltaic cell <a href="https://www.nrel.gov/docs/fy04osti/35489.pdf">takes just months</a>.</p>
<p>However, perhaps the most exciting thing about organic semiconductors is that it’s possible to design molecules that are flexible, lightweight, colored or completely transparent. <a href="http://strausslab.chem.colostate.edu/">In the lab I work in</a>, we design and test new small molecules that have specific, targeted properties – like making a simple transparent pane into a window, screen and solar panel.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/216694/original/file-20180427-135844-m0jqxy.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/216694/original/file-20180427-135844-m0jqxy.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/216694/original/file-20180427-135844-m0jqxy.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=160&fit=crop&dpr=1 600w, https://images.theconversation.com/files/216694/original/file-20180427-135844-m0jqxy.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=160&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/216694/original/file-20180427-135844-m0jqxy.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=160&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/216694/original/file-20180427-135844-m0jqxy.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=201&fit=crop&dpr=1 754w, https://images.theconversation.com/files/216694/original/file-20180427-135844-m0jqxy.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=201&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/216694/original/file-20180427-135844-m0jqxy.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=201&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Each of these research samples is a small organic solar panel made from different molecules, with varying degrees of transparency to visible light.</span>
<span class="attribution"><span class="source">Kerry Rippy</span></span>
</figcaption>
</figure>
<h2>Capturing solar energy</h2>
<p>Making a solar panel that’s also a window involves a bit of creativity: It has to be something that both absorbs light, to make electricity, and lets light through, to let people see in and out.</p>
<p>Our material takes advantage of the fact that a window only needs to transmit human-visible light; in my lab, we can make molecules that absorb only UV and infrared light, wavelengths of light our eyes don’t see. These are parts of the spectrum we don’t really want to pass through a window anyway. UV light <a href="http://www.smartskincare.com/skinprotection/uv-indoors.html">gives you a sunburn</a>. And infrared light is hot: <a href="https://techxplore.com/news/2017-06-self-powered-smart-windows-smarter.html">Filtering it out</a> can save on the energy use and expense of air conditioning. It’s true that our method doesn’t capture absolutely all the energy in sunlight, but that’s okay. The <a href="http://www.nature.com/articles/443019a">amount of solar energy that reaches Earth every hour</a> is <a href="https://www.researchgate.net/publication/6831992_Solar_Energy_A_New_Day_Dawning_Silicon_Valley_Sunrise">more than all humanity uses in a year</a>.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/217619/original/file-20180503-153881-1kn9sub.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/217619/original/file-20180503-153881-1kn9sub.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/217619/original/file-20180503-153881-1kn9sub.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=138&fit=crop&dpr=1 600w, https://images.theconversation.com/files/217619/original/file-20180503-153881-1kn9sub.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=138&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/217619/original/file-20180503-153881-1kn9sub.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=138&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/217619/original/file-20180503-153881-1kn9sub.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=173&fit=crop&dpr=1 754w, https://images.theconversation.com/files/217619/original/file-20180503-153881-1kn9sub.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=173&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/217619/original/file-20180503-153881-1kn9sub.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=173&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Transparent organic solar panels don’t absorb the part of the solar spectrum that includes visible light; they only absorb UV and infrared light.</span>
<span class="attribution"><span class="source">Kerry Rippy</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<h2>Flipping the process around</h2>
<p>Organic semiconductors are also useful for making monitors and displays. If you think about it, a screen is basically a solar panel run backwards. It generates light from an electric current. Both <a href="https://www.nrel.gov/pv/organic-photovoltaic-solar-cells.html">solar panels</a> and <a href="https://www.energy.gov/eere/ssl/oled-basics">display screens</a> involve conversions between light and electricity. Just like we can design transparent organic semiconductors, we can design molecules that emit specific colors of light when an electric current is applied. </p>
<p>Put together one molecule that emits red, one molecule that emits blue, and one molecule that emits green, and you have an organic light-emitting diode. Those are the key to what are known in the TV and monitor marketplace as OLED screens.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/217620/original/file-20180503-153881-po238k.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/217620/original/file-20180503-153881-po238k.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/217620/original/file-20180503-153881-po238k.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=247&fit=crop&dpr=1 600w, https://images.theconversation.com/files/217620/original/file-20180503-153881-po238k.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=247&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/217620/original/file-20180503-153881-po238k.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=247&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/217620/original/file-20180503-153881-po238k.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=310&fit=crop&dpr=1 754w, https://images.theconversation.com/files/217620/original/file-20180503-153881-po238k.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=310&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/217620/original/file-20180503-153881-po238k.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=310&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Simplified diagrams of organic photovoltaic cells and organic light emitting diodes show how they operate very similarly, just in reverse.</span>
<span class="attribution"><span class="source">Kerry Rippy</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>To make a smart window, we would need to deposit two layers of organic semiconductors – one layer to generate electricity from sunlight and another to emit light – onto a pan of a transparent conducting material, like <a href="https://theconversation.com/making-flexible-electronics-with-nanowire-networks-76260">indium tin oxide</a>. These technologies exist, but are <a href="https://www.treehugger.com/corporate-responsibility/samsung-unveils-see-through-solar-powered-tv.html">not yet available for sale</a>.</p>
<h2>Putting the pieces together</h2>
<p>Half of this device is already <a href="https://arstechnica.com/gadgets/2018/05/lgs-first-2018-c8-and-e8-tvs-are-here-to-prove-oled-is-finally-mainstream/">commercially available</a>: Energy-efficient high-resolution OLEDs are <a href="https://www.cnet.com/news/what-is-oled-and-what-can-it-do-for-your-tv/">a big hit in the marketplace</a> for home and office TVs.</p>
<p>Companies <a href="http://www.heliatek.com/en/">selling organic solar panels</a>, and even <a href="https://nextenergy.tech/">organic solar panel windows</a>, are just getting going. Ongoing research efforts, like mine, are aimed at optimizing the properties of these materials, increasing their efficiency, and making them more durable. </p>
<p>As we make the components better, we’ll also find ways to integrate organic-semiconductor solar cells and organic-semiconductor displays together. It may be a few years out yet, but there is certainly incentive to do so, with so many possible applications. An electric car with smart windows could collect enough solar energy to <a href="https://www.giiresearch.com/report/ix627144-smart-glass-windows-electronic-shading-semi.html">drive the car 10 to 15 miles a day</a>, enough for a typical commute. Driving directions could appear on the windshield, too. Anywhere there’s a window – whether in a skyscraper or a mobile home – there could be a smart window, saving space, saving energy and letting the occupants feel like James Bond.</p><img src="https://counter.theconversation.com/content/95352/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Kerry Rippy does not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Organic semiconductors could make possible energy-generating windows that double as movie screens or computer displays.Kerry Rippy, Ph.D. Candidate in Chemistry, Colorado State UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/737112017-02-27T20:07:33Z2017-02-27T20:07:33ZScientists create electric circuits inside plants<figure><img src="https://images.theconversation.com/files/158563/original/image-20170227-26322-nl8u98.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">Shutterstock</span></span></figcaption></figure><p>Plants power life on Earth. They are the original food source supplying energy to almost all living organisms and the basis of the fossil fuels that feed the power demands of the modern world. But burning the remnants of long-dead forests is changing the world in dangerous ways. Can we better harness the power of living plants today?</p>
<p>One way might be to turn plants into natural solar power stations that could convert sunlight into energy far more efficiently. To do this, we’d need a way of getting the energy out in the form of electricity. <a href="http://www.plant-e.com/en/plant-e-technology/">One company</a> has found a way to harvest electrons deposited by plants into the soil beneath them. But <a href="http://www.pnas.org/cgi/doi/10.1073/pnas.1616456114">new research</a> from Finland looks at tapping plants’ energy directly by turning their internal structures into electric circuits.</p>
<p>Plants contain water-filled tubes called “xylem elements” that carry water from their roots to their leaves. The water flow also carries and distributes dissolved nutrients and other things such as chemical signals. The Finnish researchers, whose work is published in PNAS, developed a chemical that was fed into a rose cutting to form a solid material that could carry and store electricity.</p>
<p><a href="http://advances.sciencemag.org/content/1/10/e1501136/tab-pdf">Previous experiments</a> have used a chemical called PEDOT to form conducting wires in the xylem, but it didn’t penetrate further into the plant. For the new research, they designed a molecule called ETE-S that forms similar electrical conductors but can also be carried wherever the stream of water travelling though the xylem goes. </p>
<p>This flow is driven by the attraction between water molecules. When water in a leaf evaporates, it pulls on the chain of molecules left behind, dragging water up through the plant all the way from the roots. You can see this for yourself by placing a plant cutting in food colouring and watching the colour move up through the xylem. The researchers’ method was so similar to the food colouring experiment that they could see where in the plant their electrical conductor had travelled to from its colour.</p>
<p>The result was a complex electronic network permeating the leaves and petals, surrounding their cells and replicating their pattern. The wires that formed conducted electricity up to a hundred times better than those made from PEDOT and could also store electrical energy in the same way as an electronic component called a capacitor.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/158569/original/image-20170227-25959-36m31e.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/158569/original/image-20170227-25959-36m31e.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/158569/original/image-20170227-25959-36m31e.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/158569/original/image-20170227-25959-36m31e.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/158569/original/image-20170227-25959-36m31e.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/158569/original/image-20170227-25959-36m31e.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/158569/original/image-20170227-25959-36m31e.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Power plants.</span>
<span class="attribution"><span class="source">Pixabay</span></span>
</figcaption>
</figure>
<h2>E-plants</h2>
<p>How well these electrical networks formed surprised even their developers. This seems to be because when the roses were treated with ETE-S, they produced the same reactive chemicals that they use to kill invading microorganisms. These chemicals made the formation of the solid electrical conductor work much better inside the plant than when it was tested in the lab.</p>
<p>There are still challenges before this discovery can achieve its full potential. Perhaps most importantly, they need to find a way of getting ETE-S (or some further improved chemical) into intact, living plants. But the creation of “e-plants”, that is plants with integrated electronic circuits, now looks much closer.</p>
<p>So how could e-plants be used? The most exciting possibility will be if we can combine e-plant electrical storage and circuitry with some way to directly tap photosynthetic energy, creating a literally green energy source. </p>
<p>But the technology could also help us better understand regular plants. Plants do not have a nervous system as animals do, but they do use <a href="http://www.annualreviews.org/doi/abs/10.1146/annurev-arplant-043015-112130">electrical signals</a> both to control individual cells and two carry messages between different parts of the plant. Perhaps the most spectacular example of this is in the Venus flytrap, in which the snapping mechanism is <a href="http://www.tandfonline.com/doi/full/10.4161/psb.2.3.4217">activated by an electrical impulse</a>.</p>
<p>Building electrical circuits into plants will allow us to listen into these messages more easily. Perhaps when we understand their “language” better, we will then be able to send instructions to the plant. For example turning on its defence systems if we know that it is at risk of disease.</p>
<p>Perhaps we could create electronic plants that function like machines. If a crop could tell us if it has too little water or fertiliser, or is being attacked by insects, we could move resources to where they are most needed, improving farming efficiency. Maybe one day you could even use the technology to adjust a flower’s fragrance to match your mood.</p><img src="https://counter.theconversation.com/content/73711/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Stuart Thompson has received funding from MAFF and the Nuffield Foundation. </span></em></p>Do androids smell electric roses?Stuart Thompson, Senior Lecturer in Plant Biochemistry, University of WestminsterLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/632872016-10-10T11:22:13Z2016-10-10T11:22:13ZThree ways organic electronics is changing technology as we know it<figure><img src="https://images.theconversation.com/files/139765/original/image-20160929-27037-1ckn6ew.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption"></span> <span class="attribution"><a class="source" href="http://www.ntech.t.u-tokyo.ac.jp/en/press/press_for_media/ScienceAdvances20160415/index.html">Someya Laboratory/University of Tokyo</a></span></figcaption></figure><p>One day, your latest gadget won’t be in your pocket like a phone or even wrapped around your wrist like a smartwatch, but stuck to your skin like a transparent plaster. Researchers at the University of Tokyo are the latest group to attempt to make this kind of “<a href="http://advances.sciencemag.org/content/2/4/e1501856">optoelectronic skin</a>”, with an ultra-thin, flexible LED display that can be worn on the back of your hand.</p>
<p>What makes this possible is the field of “organic electronics”, which can also be used to create a range of technologies from printed solar cells to computer screens you can roll up and put in your pocket. The name comes from the use of “organic” semiconductors, which are made with materials based on carbon rather than silicon as in conventional electronics. And while optoelectronic skins are still being developed – organic electronics are already changing the technology we buy.</p>
<figure class="align-left ">
<img alt="" src="https://images.theconversation.com/files/139766/original/image-20160929-27037-tivd4s.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/139766/original/image-20160929-27037-tivd4s.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=684&fit=crop&dpr=1 600w, https://images.theconversation.com/files/139766/original/image-20160929-27037-tivd4s.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=684&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/139766/original/image-20160929-27037-tivd4s.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=684&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/139766/original/image-20160929-27037-tivd4s.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=859&fit=crop&dpr=1 754w, https://images.theconversation.com/files/139766/original/image-20160929-27037-tivd4s.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=859&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/139766/original/image-20160929-27037-tivd4s.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=859&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Tokyo’s ultraflexible organic optical sensor.</span>
<span class="attribution"><span class="source">Someya Laboratory/University of Tokyo</span></span>
</figcaption>
</figure>
<p>Organic semiconductor materials typically come in two forms: as a small molecule consisting of a few tens or hundreds of atoms, or as long chains of thousands of repeating molecules (a plastic). The latter is particularly interesting, because we don’t normally think of plastics as conductors of electricity. But during the 1970s <a href="http://www.nobelprize.org/nobel_prizes/chemistry/laureates/2000/popular.html">researchers realised</a> they could make some plastics act as conductors, and some as semiconductors (which conduct electricity only under certain conditions).</p>
<p>For many years the electrical performance of semiconducting plastics and small molecules has lagged behind the inorganic (non-carbon based) semiconductors that underlie many of our modern computer chips. But thanks to <a href="http://onlinelibrary.wiley.com/doi/10.1002/adma.201304346/full">continued research and development</a> there are now organic semiconductors with good enough performance that they are starting to be commercialised in new and exciting applications.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/peE8Sm5xEz8?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Video of organic semiconductor inks being used to print electrical circuits.</span></figcaption>
</figure>
<p>The chemistry of organic semiconductors can be modified in ways that are impossible with materials such as silicon. Organic semiconductors can be made to be soluble, and can be turned into an ink. This means it’s possible to print electronic circuits, with the potential to manufacture components as fast as printing newspapers. And because they’re based on plastic materials, these circuits can also be made flexible and so no longer need to sit inside rigid boxes.</p>
<p>Here are three ways organic electronics are already altering the way we use technology.</p>
<h2>Flexible lights</h2>
<figure>
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<p>Organic light-emitting diodes (OLEDs) are the big success story of organic electronics so far, and you may already use them as part of OLED displays in some high-end TVs and smartphones. They are now being considered as a new way to light homes. OLEDs are effectively a sandwich of one or more organic semiconductors in between layers that allow different electrical charges into the semiconductor. As charges meet in the middle of the sandwich, <a href="http://www.explainthatstuff.com/how-oleds-and-leps-work.html">they combine together to give out light</a>.</p>
<p>Unlike inorganic light-emitting diodes, an OLED light can be made on large plastic sheets. This means you could use OLEDs as flexible light-emitting surfaces to create <a href="https://theconversation.com/why-you-should-get-ready-to-say-goodbye-to-the-humble-lightbulb-57404">new ways of lighting rooms</a>, that aren’t reliant on point sources such as bulbs.</p>
<h2>Flexible displays</h2>
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<p>Another application for OLEDs are in displays. They are particularly popular with TV manufacturers because they generate light directly and so don’t need the <a href="https://en.wikipedia.org/wiki/LCD_television#Building_a_display">white backlight and filters</a> that are found in other technologies, meaning the overall display can be thinner. They also open the possibility of making flexible displays and several electronics manufacturers are expected to <a href="http://www.bloomberg.com/news/articles/2016-06-07/samsung-said-to-consider-phones-with-bendable-screens-for-2017-ip4tgwz9">launch bendable products</a> in the next few years, although this is <a href="https://theconversation.com/why-are-flexible-computer-screens-taking-so-long-to-develop-53143">not without its challenges</a>.</p>
<p>Flexible displays rely upon electronic switches known as transistors. These <a href="http://web.mit.edu/%7Ejoyp/Public/OFET%20Term%20Paper.pdf">organic field-effect transistors</a> (OFETs) are also made from organic semiconductors. Behind each OLED pixel in the display is an OFET, ready to turn it on and off as required. OFETs work by having three electrical connections: the gate, source and drain. A voltage applied to the gate makes the semiconductor either more or less conductive. This either allows or prevents electrical current from flowing between the source and drain.</p>
<h2>Printed solar cells</h2>
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<p>Just as organic electronics can be used to generate light, they can also convert light into electricity when used in solar panels. Organic photovoltaics (OPVs) have a very <a href="http://www.sigmaaldrich.com/materials-science/organic-electronics/opv-tutorial.html">similar structure</a> to OLEDs and can do the same job as the silicon-based solar panels already used across the world. The key difference is that they can be made rapidly on thin plastic sheets using established printing processes. As well as reducing manufacturing costs, this means you could stick them to virtually <a href="https://theconversation.com/how-trillions-of-tiny-solar-panels-could-power-the-internet-of-things-50023">any surface or object</a> for a ready-made source of power.</p>
<p>Although organic photovoltaics aren’t currently as efficient at generating electricity as conventional solar panels, their performance has been steadily increasing <a href="http://www.nrel.gov/ncpv/images/efficiency_chart.jpg">over the past decade</a>. However there are still <a href="http://www.energy.gov/eere/sunshot/organic-photovoltaics-research">significant research</a> <a href="https://www.epsrc.ac.uk/research/ourportfolio/researchareas/solartech/">efforts</a> and there are a number of companies <a href="http://www.heliatek.com/en/">already developing</a> <a href="https://www.infinitypv.com/">and selling</a> panels.</p>
<p>While these advances are already happening, there is a far wider range of potential uses for organic electronics. From the University of Tokyo’s electronic plasters for health monitoring to <a href="http://pubs.rsc.org/en/content/articlehtml/2014/cs/c3cs60235d">biodegradable gadgets</a>, these materials promise an exciting future of new technologies.</p><img src="https://counter.theconversation.com/content/63287/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Stuart Higgins currently researches materials for innovative biomedical interfaces, work funded by the ERC.
He previously worked on the joint academic/industry project 'Security tags Enabled by near field Communications United with Robust Electronics' (SECURE), funded by Innovate UK. His PhD in the field of plastic electronics was funded by the Engineering and Physical Sciences Research Council (EPSRC). He has previously collaborated with companies FlexEnable Ltd and VTT.</span></em></p>Flexible plastic electronics are already altering the world around us.Stuart Higgins, Research Associate, Imperial College LondonLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/610482016-06-29T13:19:20Z2016-06-29T13:19:20ZThe next wearable technology could be your skin<figure><img src="https://images.theconversation.com/files/128697/original/image-20160629-15274-10c0124.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">Chris Harrison, Scott Saponas, Desney Tan, Dan Morris - Microsoft Research</span>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span></figcaption></figure><p>Technology can be awkward. Our pockets are weighed down with ever-larger smartphones that are a pain to pull out when we’re in a rush. And attempts to make our devices more easily accessible with smart watches have so far <a href="https://theconversation.com/apple-delivers-smart-watch-but-you-might-want-to-think-twice-about-getting-one-31526">fallen flat</a>. But what if a part of your body could become your computer, with a screen on your arm and maybe even a direct link to your brain?</p>
<p>Artificial electronic skin (e-skin) could one day make this a possibility. Researchers are developing flexible, bendable and even stretchable electronic circuits that can be applied directly to the skin. As well as turning your skin into a touchscreen, this could also help replace feeling if you’ve suffered burns or problems with your nervous system.</p>
<p>The simplest version of this technology is essentially an electronic tattoo. In 2004, <a href="http://informationdisplay.org/IDArchive/2014/JanuaryFebruary/FrontlineTechnologyImperceptibleElectronic.aspx">researchers in the US and Japan</a> unveiled a pressure sensor circuit made from pre-stretched thinned silicon strips that could be applied to the forearm. But inorganic materials such as silicon are rigid and the skin is flexible and stretchy. So researchers are now looking to electronic circuits made from organic materials (usually special plastics or forms of carbon such as graphene that conduct electricity) as the basis of e-skin.</p>
<p>Typical e-skin consists of a matrix of different electronic components – flexible transistors, organic LEDs, sensors and organic photovoltaic (solar) cells – connected to each other by <a href="http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4531887/">stretchable or flexible</a> conductive wires. These devices are often built up from very thin layers of material that are sprayed or evaporated onto a flexible base, producing a large (up to tens of cm<sup>2)</sup> electronic circuit in a <a href="http://pubs.rsc.org/en/content/articlehtml/2014/cs/c3cs60235d">skin-like form</a>. </p>
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<p>Much of the effort to create this technology in the last few years has been driven by robotics and a desire to give machines human-like sensing capabilities. <a href="https://spie.org/membership/spie-professional-magazine/spie-professional-archives-and-special-content/2011jan-archive/better-electronic-sensors-skin">We now have</a> e-skin devices that can detect approaching objects and measure temperature and applied pressure. These can help robots work more safely by being more aware of their surroundings (and any humans that might get in the way). But if <a href="https://micro.seas.harvard.edu/papers/Menguc_ICRA13.pdf">integrated with wearable technology</a>, they could do the same for humans, detecting, for example, harmful movements during sport.</p>
<p>The technology has also led to the creation of <a href="https://theconversation.com/why-are-flexible-computer-screens-taking-so-long-to-develop-53143">bendable screens</a>, while at least <a href="http://www.cicret.com">one company</a> is hoping to turn the skin into a touchscreen using sensors and a pico-projector rather than a display.</p>
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<p>But will we one day come to build this technology directly into our bodies, and how common will it be? The problem with organic electronics at the moment is that they aren’t very reliable and give relatively poor electronic performance. Just like real skin, the e-skin developed so far <a href="http://www.mdpi.com/1424-8220/14/7/11855/pdf">eventually develops wrinkles</a>. These cause its layers to come apart and the circuits to fail. Plus, atoms in organic materials are more chaotically organised than the inorganic materials used to make traditional electronics. This means electrons <a href="http://inside.mines.edu/%7EZhiwu/research/papers/G02_charge_transfer.pdf">move 1,000 times slower</a> in organic materials, so devices made from them will operate much more slowly and would’t deal as well with the heat the circuits generate.</p>
<h2>Bio-compatibility</h2>
<p>The other big issue is how to integrate e-skin with the human body so that it doesn’t cause medical problems and so that it can interface with the nervous system. Organic materials are carbon-based (like our bodies) so in some senses are more likely to be biocompatible and not rejected by the body. But carbon particles are good at passing through the cells that make up our body and this would likely to lead to inflammation, generating an immune response that could even, according to <a href="http://www.materialstoday.com/carbon/articles/s1369702112701013/">certain unverified theories</a>, generate tumours. </p>
<p>However, scientists have already had some success linking electronic devices to the nervous system. Researchers at the <a href="https://www.researchgate.net/publication/285999946_Ultrathin_short_channel_thermally-stable_organic_transistors_for_neural_interface_systems">University of Osaka</a> are leading pioneering research to develop a brain implant from a flexible matrix of organic thin-film transistors that could be activated just by thinking. The difficulty is that such an invasive approach could lead to further problems, especially when we start testing the technology on humans. </p>
<p><a href="http://onlinelibrary.wiley.com/doi/10.1002/adma.201303349/full">In coming years</a> we are are likely to see prototype e-skin devices gaining momentum in the form of wearable bodily sensors, and potentially as a way to harvest energy from the body’s movement. What will take much longer are the more complicated circuits such as those found in smartphones. And the other big question we’ve yet to answer is how many people will accept permanent or semi-permanent electronic implants. Would you be willing to effectively become a cyborg?</p><img src="https://counter.theconversation.com/content/61048/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Luca Santarelli is funded by a EC Marie Curie ITN-CONTEST project (n. 317488).
</span></em></p>Imagine if your smartphone was built into your arm. Flexible organic electronics could one day make artificial skin displays a reality.Luca Santarelli, PhD Candidate, UCLLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/574042016-06-13T13:28:10Z2016-06-13T13:28:10ZWhy you should get ready to say goodbye to the humble lightbulb<figure><img src="https://images.theconversation.com/files/126293/original/image-20160613-29205-1gffexx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">University of Bath</span></span></figcaption></figure><p>Lightbulbs are disappearing. The traditional incandescent bulbs that revolutionised daily life in the 20th century have largely already gone and the energy efficient fluorescent bulbs that replaced them are now also on their way out. In their place, we now have highly efficient light emitting diodes (LEDs), which are small semiconductor devices that produce light when an electric current is passed through them.</p>
<p>But even these are often arranged in a device that looks something like a conventional lightbulb. The technology that comes next could do away with the concept of rooms having a single light source and instead build light into ceilings and walls. This new type of organic LED (OLED) will redefine how we think about lighting.</p>
<p>OLEDs are not bulbs but films of layered organic semiconductors, meaning that they are made from carbon and hydrogen, just like organic life. There are <a href="http://www.sigmaaldrich.com/materials-science/material-science-products.html?TablePage=19353440">two main families</a> of OLED: those based on small molecules and those employing polymers. Organic LEDs aren’t connected to organic food or farming but they are very efficient and do not contain toxic metals, such as mercury, so they are a <a href="http://www.sciencedirect.com/science/article/pii/S1369702112701396">green technology</a>.</p>
<p>Conventional LEDs produce sharp points of light and cannot produce white light so LED bulbs usually mix different colours to approximate natural light but often do so with a blue tinge. In contrast, OLEDs emit a soft, diffuse light that’s colour can be tuned to mimic natural light as closely as the old incandescent lamps. The technology provides fast switch-on times, wide operating temperatures and no noise. </p>
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<img alt="" src="https://images.theconversation.com/files/126297/original/image-20160613-29238-13yynom.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/126297/original/image-20160613-29238-13yynom.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=472&fit=crop&dpr=1 600w, https://images.theconversation.com/files/126297/original/image-20160613-29238-13yynom.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=472&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/126297/original/image-20160613-29238-13yynom.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=472&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/126297/original/image-20160613-29238-13yynom.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=593&fit=crop&dpr=1 754w, https://images.theconversation.com/files/126297/original/image-20160613-29238-13yynom.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=593&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/126297/original/image-20160613-29238-13yynom.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=593&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<span class="caption">Alison Walker and colleague Enrico Da Como experimenting with OLED panels.</span>
<span class="attribution"><span class="source">University of Bath</span></span>
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<p>But perhaps the most interesting thing about OLEDs is that the films they are made from are just 0.3mm wide and can be moulded into flexible, transparent lighting panels and twisted into different shapes. This means OLED lights won’t just be small fittings placed in the middle of a ceiling. Instead, they can be made in a variety of sizes and shapes and fitted to different parts of a room, or even used to create animated screens or <a href="http://www.cnet.com/uk/news/lg-displays-latest-oled-tv-sticks-to-the-wall-is-under-1mm-thick/">wirelessly updatable wallpaper</a>.</p>
<p>It also means they could be made using <a href="http://semimd.com/blog/tag/oleds/">additive manufacturing</a> processes – essentially printing the entire technology onto a wall or ceiling panel or other flexible base. This would reduce waste because you only print what you need and you can manufacture the lights locally, reducing their environmental impact. They also don’t require the high temperature curing ovens used to make conventional LEDs.</p>
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<p>An <a href="http://www.explainthatstuff.com/how-oleds-and-leps-work.html">OLED lighting panel</a> comprises multiple layers of organic material that are each tens of nanometers thick. These are sandwiched between two electrodes, a transparent conducting base layer and a metallic top layer. When electricity passes between these electrodes, it causes the organic material in between to emit light. Certain organic molecules in the layers act as “dopants” which determine the wavelength and so the colour of the light.</p>
<h2>Bringing the cost down</h2>
<p>Despite all the advantages of OLEDs, it may still take a while for them to take over from existing light fittings. The main reason we don’t already have OLEDs in our homes is the price tag. <a href="http://www.inter-lumi.com/m_article/16-At-what-price-consumers-will-adopt-OLED-lighting.html">Industry experts</a> expect OLED lighting will become a major market by 2020-2023, when OLED panels are expected to cost €200 per square metre (down from €7,000 today).</p>
<p>Cheaper OLEDs should be made possible by developing faster manufacturing methods. <a href="http://www.techhive.com/article/3018446/smart-tv/oled-vs-led-theres-just-no-comparison.html">We also need</a> to find a way to ensure the blue light emitting molecules in OLEDS last as long as those that produce green and red emissions. OLEDWorks, a New York-based lighting company that bought the OLED division from Philips Lighting in 2015, already has <a href="http://electronicdesign.com/leds/oled-lighting-flickers-through-growing-pains">several products</a> with 50,000-hour lifespans – comparable to existing LED lights. Once these goals are achieved we should be prepared for any part of a room – or object within it – to light up when we flick the switch.</p><img src="https://counter.theconversation.com/content/57404/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Alison Walker receives funding from the European Union Horizon 2020, H2020, research and innovation programme for the project Extmos, EXTended Model of Organic Semiconductors under grant agreement 64617, and the Seventh Framework Programme Initial Training Network Destiny, DyE SensiTIzed cells with eNhanced stabilitY under grant agreement 316494 both of which she coordinates. In addition she is funded by the H2020 Energy Oriented Centre of Excellence, EoCoE under grant agreement 676629. She is also funded by the UK Engineering and Physical Sciences Research Council Centre for Doctoral Training in New and Sustainable Photovoltaics (which she coleads), the Supersolar hub, and Doctoral Training Award studentships and by the University of Bath for studentships.</span></em></p>Flexible light-emitting screens mean you soon won’t need bulbs because your wallpaper – or even your furniture – will light up at the flick of a switch.Alison Walker, Professor of physics, University of BathLicensed as Creative Commons – attribution, no derivatives.