tag:theconversation.com,2011:/us/topics/organic-photovoltaics-22395/articlesOrganic photovoltaics – The Conversation2018-07-31T10:40:24Ztag: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>
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<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>
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<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>
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</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/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>
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<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">
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<span class="caption">Tokyo’s ultraflexible organic optical sensor.</span>
<span class="attribution"><span class="source">Someya Laboratory/University of Tokyo</span></span>
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<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>
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<figcaption><span class="caption">Video of organic semiconductor inks being used to print electrical circuits.</span></figcaption>
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<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>
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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/500232015-11-09T10:17:23Z2015-11-09T10:17:23ZHow trillions of tiny solar panels could power the internet of things<figure><img src="https://images.theconversation.com/files/100647/original/image-20151103-16542-1gigpu1.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.shutterstock.com/pic-273793955/stock-vector-smart-home-automation-vector-background-icons-symbols-for-various-devices-and-sensors-light.html?src=0slexbTroyRoNIQ7drr0FA-4-47">Shutterstock</a></span></figcaption></figure><p>It could herald a great leap forward in the way we live our lives. The <a href="https://theconversation.com/uk/topics/internet-of-things">internet of things</a>, the idea that objects can be interconnected via a global network, will run your home, keep you healthy and even check how much food is <a href="https://theconversation.com/amazon-dash-is-a-first-step-towards-an-internet-of-things-that-is-actually-useful-39711">in your fridge</a>. It will mean <a href="http://motherboard.vice.com/blog/the-internet-of-things-could-be-the-biggest-business-in-the-history-of-electronics">a trillion new “smart sensors”</a> being installed around the world by 2020. But what’s going to power these devices?</p>
<p>In some cases, the energy source is obvious: sensors in fridges or traffic lights can simply tap into mains electricity. But it’s much trickier to power something that detects water quality in remote reservoirs, cracks in railway lines, or whether a farmer’s <a href="http://blogs.ptc.com/2014/06/17/even-cows-are-connected-to-the-internet-of-things/">cows are happy and healthy</a>.</p>
<p>Organic solar panels might be the answer. They’re cheap, and are flexible enough to power minuscule sensors whatever their shape. The cells can be just <a href="http://www.nature.com/ncomms/journal/v3/n4/full/ncomms1772.html">two micrometres thick</a> – around a 50th the width of a human hair – but they are able to absorb a huge amount of light for such a thin surface.</p>
<p>These <a href="http://www.bangor.ac.uk/eng/research/organic_electronics.php.en">organic photovoltaics</a> (OPVs) differ from silicon solar cells as they can be made entirely from specially-synthesised organic materials, which are deposited onto cheap substrates such as <a href="http://www.napcor.com/PET/whatispet.html">PET</a>, a form of polyester also used in soft drink bottles and crisp packets. This material is lighter, more flexible and can even be tuned to provide different colours – who said solar cells have to be plain black?</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/101055/original/image-20151106-16258-qtlfsq.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/101055/original/image-20151106-16258-qtlfsq.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/101055/original/image-20151106-16258-qtlfsq.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=662&fit=crop&dpr=1 600w, https://images.theconversation.com/files/101055/original/image-20151106-16258-qtlfsq.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=662&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/101055/original/image-20151106-16258-qtlfsq.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=662&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/101055/original/image-20151106-16258-qtlfsq.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=832&fit=crop&dpr=1 754w, https://images.theconversation.com/files/101055/original/image-20151106-16258-qtlfsq.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=832&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/101055/original/image-20151106-16258-qtlfsq.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=832&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Jazz up your room with a pink solar panel.</span>
<span class="attribution"><span class="source">Iwan Saunders Jones / Bangor</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>Critically, it takes <a href="http://pubs.rsc.org/en/content/articlehtml/2012/ee/c1ee02728j">just one day</a> for OPVs to earn back the energy invested in their manufacture, known as the “energy payback time”, which compares to <a href="http://www.researchgate.net/publication/273818473_Energy_payback_time_(EPBT)_and_energy_return_on_energy_invested_(EROI)_of_solar_photovoltaic_systems_A_systematic_review_and_meta-analysis">around one to two years</a> for regular silicon solar cells.</p>
<p>Organic photovoltaics can also be moulded onto 3-D surfaces such as roof tiling or even clothing. In our <a href="http://pubs.rsc.org/en/Content/ArticleLanding/2015/EE/c5ee02162f#!divAbstract">latest research</a>, colleagues and I demonstrated that this makes them more effective at capturing diffuse or slanting light. This wouldn’t make much difference for a regular solar farm in a sunny country, but cloudier places at higher latitudes would see benefits. </p>
<p>For the internet of things, however, these improvements are a game-changer. Few of those trillion sensors will be placed conveniently in the sunshine, facing upwards; far more will be in unusual locations where light only falls indirectly. Tiny organic solar cells will enable energy to be captured throughout the day, even indoors or when attached to clothes.</p>
<h2>From billions to a trillion</h2>
<p>There’s no denying the huge need for such a technology. The “trillion sensors” figure at first seems outlandish, but consider the fact that a typical smartphone, for example, possesses <a href="http://www.techradar.com/news/phone-and-communications/mobile-phones/sensory-overload-how-your-smartphone-is-becoming-part-of-you-1210244">around ten smart sensors</a> that measure light, temperature, sound, touch, movement, position, humidity and more. More than <a href="http://www.idc.com/getdoc.jsp?containerId=prUS25860315">a billion smartphones</a> will be sold this year, so that’s 10 billion new sensors just in phones. And not all smart sensors are confined to smartphones, of course; they are already routinely used in personal care, environmental monitoring, security and transport.</p>
<p>Whatever the exact numbers, we can assume that many, many more sensors will be deployed in future and their complexity and usefulness is growing exponentially. My colleagues and I at Bangor are interested in how we could power them all, which is what led us to organic solar.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/101062/original/image-20151106-16277-uvkxvz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/101062/original/image-20151106-16277-uvkxvz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/101062/original/image-20151106-16277-uvkxvz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=374&fit=crop&dpr=1 600w, https://images.theconversation.com/files/101062/original/image-20151106-16277-uvkxvz.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=374&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/101062/original/image-20151106-16277-uvkxvz.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=374&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/101062/original/image-20151106-16277-uvkxvz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=470&fit=crop&dpr=1 754w, https://images.theconversation.com/files/101062/original/image-20151106-16277-uvkxvz.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=470&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/101062/original/image-20151106-16277-uvkxvz.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=470&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Wobble power? Organic solar cells can be shaped to fit different surfaces or devices.</span>
<span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:CSIRO_ScienceImage_1502_Dr_Scott_Watkins_holding_a_sheet_of_flexible_solar_cells.jpg">CSIRO</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<p>Though engineers will always try to reduce energy consumption through better design and putting sensors to “sleep” when they are not required, even ultra-low power sensors still <a href="http://www.gassensing.co.uk/product/cozir-ambient/">consume around 3.5mW (milliWatts) per measurement</a>. Poorer quality sensors might use considerably more.</p>
<p>Now assuming the “average” sensor actually consumes 5mW per measurement, and assuming one measurement is made every minute and takes 30 seconds to complete, this average smart sensor will need 22 Wh (watt-hours) in a calendar year. On it’s own, this is not a substantial value and equivalent to running your TV for about five minutes.</p>
<p>But it all adds up. Based on this simple analysis, 1 trillion sensors will use 21,900 Gigawatt hours (GWh) per year. That’s an incredible demand on electricity grids, equivalent to the combined output from a few typical nuclear power plants. This is all before considering the extra demand needed by data centres to handle and store such large sums of information.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/101092/original/image-20151106-16253-13laruu.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/101092/original/image-20151106-16253-13laruu.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/101092/original/image-20151106-16253-13laruu.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=257&fit=crop&dpr=1 600w, https://images.theconversation.com/files/101092/original/image-20151106-16253-13laruu.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=257&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/101092/original/image-20151106-16253-13laruu.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=257&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/101092/original/image-20151106-16253-13laruu.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=323&fit=crop&dpr=1 754w, https://images.theconversation.com/files/101092/original/image-20151106-16253-13laruu.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=323&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/101092/original/image-20151106-16253-13laruu.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=323&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 single organic solar cell (left) can be wrapped around a human hair – while still generating electricity.</span>
<span class="attribution"><a class="source" href="http://www.nature.com/ncomms/journal/v3/n4/fig_tab/ncomms1772_F1.html">Kaltenbrunner et al / Nature Comms</a></span>
</figcaption>
</figure>
<p>Yes, low-power electronics will be developed that should reduce the amount of energy that the sensors need. But, for long term operation, many sensors can’t rely upon an internal battery, as a battery has a finite energy store. This is particularly pertinent as many smart sensors may be placed in remote locations, often far from the electricity grid or without a power connection. </p>
<p>Therefore we must create smart sensors that can harvest their own energy from the local environment – and it’s here that organic solar technology will find its niche.</p><img src="https://counter.theconversation.com/content/50023/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Jeff Kettle receives funding from the Wales Ireland Network for Innovative Photovoltaic Technologies (WIN-IPT) project, funded through the Interreg 4A, Wales Ireland Programme 2007-13</span></em></p>It’s not easy powering a network of billions of sensors. But this could be a solution.Jeff Kettle, Lecturer in Electronic Engineering, Bangor UniversityLicensed as Creative Commons – attribution, no derivatives.