A "Eureka" for Solar Energy | Bert Conings | TEDxUHasselt

[Music] did you know that the sunlight the energy coming from the sunlight onto the earth is almost three thousand times the amount of energy that we need to sustain our daily activities that makes the Sun our most abundant renewable energy source much more so than the other renewable energy sources and that's important to know because with climate change and pollution going on we need to invest in renewables as good as we can and one major advantage of solar energy is it's decentralized character power can be delivered directly to the individual so by show of hands how many of you have solar panels on the roofs wow that's impressive and and how many of you would really like to get them once the opportunity presents itself Wow I'm impressed I'm really impressed that's absolutely the spirits because if we go on like this at some point we will get there that's the total the cumulative amount or area of solar panels in the world equals the area of the country of Spain at that point we would be fully self-sufficient on solar power alone or a level even Trump that I bet you didn't know that's given current technology but also limitations in the use of space and all that we could safely power the world three times well if that's not encouraging then I don't know what is of course in all of this a central part central role is played by the technology what type of materials are we using to convert sunlight into electricity I'm sure you're all familiar with these apparently you have to these are silicon solar cells and they make up 92 to 93 percent of all installed solar panels in the world and that includes the one I had on my head 20 years ago a little bit more to power the little fan to keep me cool during the summer safe to say of course that already at a very young age I saw the potential of this technology of course no seriously photovoltaics has become booming business but predominantly in the last decades mostly due to reduction in price points but there has been an increase of a factor of 30 and for most of this increase we have silicon technology to thank well that's great isn't it it's established technology people are buying it everywhere it works fine that's absolutely fantastic would be almost sacrilege to think that may be out there it could be an alternative no no no why would we change a wedding team I'm not I'm not going to go into that discussion not going to do that instead let me take you onto a journey to a much smaller scale the scale of atoms and molecules and an analogy that I really like to make is that chemistry and material science is like Lego for adults for advanced people if you will everything everything we are our whole lives everything we touch we use it's basically us grabbing from this box we can combine bricks to make composite breaks and design materials but in the end no matter how you look at it every tangible aspect of our lives boils down to us grabbing in this box that's also why would happen to New Jersey at Bell Labs in the 1950s they were avid Lego builders they were playing around with silicon and some points I had a piece of silicon they put electrodes on top they held it into the light and they discovered that silicon could capture the light and convert them to electricity that was new that was new and that's basically a first-order approximation as we physicists say how is silicon solar cell was born by the introduction sorry by the discovery of its special properties how about that silicon now suppose these gray spheres are silicon atoms then this is how silicon likes to sit it's just what nature dictates and that's how it gets special properties now how do we build a solar cell from this well this little cube is actually a repeating unit a unit cell you can put one next to the other you can put them on top of each other you can build that's how it works so conceptually speaking we can start with one unit cell attached some others build some other bricks keep building building building and in the end we put some electrodes on top and we have a solar cell of course I did leave out some pretty crucial details here this is not something you do on the kitchen counter but yeah that's how it works silicon solar cells are a bit difficult silicon you see silicon needs to be ultra pure to unlock its desirable properties that means you need to treat it in industrial environments wearing funky spacesuits and all yeah that's what you need to do so silicon needs to be 99.9999% pure to make good use of it for photovoltaics so for every million of silicon atoms there can only be one intruder some kind of contamination so if you would be the CEO of a company called silicon incorporated very big company 1 million employees but there are two idiots working for you bankrupt your company and so it goes with silicon and then when the silicon is pure then we need to purposefully add trace amounts of other metals in there again to make it conductive and the associated processes with that are pretty high in temperature up to 1,400 degrees 1,400 degrees that is more than the melting temperature of gold silver aluminium typical metals metal to make a product which has fairly little wiggle room in its properties and it's what it looks like so that kinda makes us feel that there might be some room for improvements here or there but silicon is only silicon there's one type of atom and I'm sure you're all very frustrated as a kid when you ended up with only one type of Lego bricks there's only so many things you can make with one type one type of Lego bricks indeed I understand and someone else was very frustrated about this five years ago was Mike Lee Mike Lee was a graduate students and research group of Professor Henry Snape there were also crazy Lego builders and they were also looking for new building blocks for photovoltaics for photovoltaic materials at some point they came up with this mad scientist no seriously seriously this is ingenious this is a recipe for a wondrous material called perovskites for ross gates so by the way these are some of the original first notes on the topic and I have to thank both dr. Lee and professor Sneyd for sending these pictures to me to share with you today so profs got new material you remember the the repeating units of silicon well Mike Lee discovered that you can make repeating units that look like this if you just take the right elements bring them together and the right conditions but still using fairly basic chemistry and he succeeded in making high-efficiency solar cells from these materials as well that was five years ago so how is the evolution until today well let me show you a timeline of power conversion efficiencies of silicon solar cells versus brass gate silicon has been around for a long time but broths kite is the fastest developing photovoltaic technology of all time and it's quickly approaching silicon in terms of efficiency so in that sense it would be almost ready for commercialization on such a short time scale that is a may sing or at least I think it's amazing I see some faces now to say well Birds I see your point nice but I don't really understand why you're making such a big fuss out of this I'm glad you said so so first of all the price guys that mike lee made consisted of these elements but little stroll through literature learns us that there are many more possibilities I probably missed some I'm sure so rough kite is not really the name of one material it is the name of a family of materials that likes to structure itself in a certain structure that we call perovskites but there are numerous possibilities to choose from to make that structure and that that is the main advantage of perovskite over silicon because if there's a lot of wiggle room a lot of possibilities in which elements you choose then also you can tune the properties to a very large extent one of these properties that you can tune is color now a very dark solar cell is always the most efficient one silicon solar cells also pretty dark and we make frost gets pretty dark as well but cartooning does have its perks the first one I want to discuss with you is fairly technical so please bear with me solar cell is basically a layered structure with a good stuff in the middle and then some other slightly less exciting but still very necessary things on the sides and I told you we can change the color of the profs card it's another way of saying we can change which part of the light it absorbs so if we design to perovskites that I absorb another part of the light we can make solar cell like this and just stack them we have a solar cell that absorbs more energy on the same area why does this work so well well this is called a tandem solar cell pretty sure you've seen people on tandem bikes they're not just necessarily overachievers but they also go quite fast that's because there are two engines on the bike but it's just the same friction and drag as a normal bike so they go faster that's a tandem solar cell this is no piece of theory in a recent work by the University of Oxford Stanford Washington and ourselves also - University we show that this principle actually works and in the future we will be able to stack even more layers eventually to make solar cells that are twice the efficiency of the current silicon solar cells so that was a technical part about collar tuning of course when you think about collar tuning first thing that comes to mind is aesthetics in general architects are not really wildly enthusiastic about solar cells solar panels because while the look of a classical solar panel doesn't match the style of many buildings but that can be a thing of the past with perovskites we can even make them semi-transparent so they can be integrated into windows and the ultimate art and all of this is called building integrated photovoltaics I'll give you an example that you might recognize this is a picture from Tesla company that is well known for its electric cars and they announced that they would also commercialize photovoltaic roof tiles so so our panels are still there but unless we tell you you probably won't notice that's what building integrated photovoltaics is all about but with perovskites we can take this to the extreme any possible surface that is available on a building could be a light harvesting surface a whole building envelope could be one big solar cell instead of putting solar cells on the roof we can integrate them as an actual part of the building and having it looking pretty at the same time so you might wonder well not all buildings are the same there are some tricky shapes there some tailor to work it must be very expensive as well those are valid concerns but not to worry again we can capitalize on special properties of profs kites you see silicon was rigid and brittle and you can make it only in relatively small pieces so its production is like a batch process but perhaps guides can be made in large areas flexibly and work in a continuous way so it gets better profs guides don't need to be 99.9999% pure they can have a smudge here and there doesn't really matter so we can make them at room temperature or close to room temperature and we can also do that with fairly simple techniques in fact I'm sure that most of you would be able to make prof. skate solar cell and the comfort of your own homes not in the kitchen not in the in the shed in the garden no but in your office space or wherever your printer is located because indeed profs kite solar cells can be printed they can be printed much like newspapers are printed basically instead of having a row of paper you have a roll of plastic instead of having regular ink you have a special props kite ink and resulting ribbon you can just cut it too for the application that you want you can even have bendy shapes no problem at all they're flexible anyway it's large piece next time your your grandmother's birthday is coming up you buy her a photovoltaic tablecloth or something or something equally sexy you can you can buyer or for yourself obviously you can buy a solar charger for your phone you hold it into the sunlight phones charge to roll it up and you're off or if you're on the move a lot you can buy a bag with an active solar part to charge your tablet or your phone if you like hiking why not buy it dance with flexible brass kite solar cells worked into them and while you're in the store anyway might as well buy the jacket if you don't like hiking you can get yourself an artificial tree with with brass kite solar leaves why not or for those DIY people among us we can buy photovoltaic tape and we can stick it wherever we need instant power so there can be peroxides and consumer electronics bags tents boats cars planes I mean any type of construction anywhere you want it can be a whole photovoltaic rough sky landscape so the Sun is our most abundant renewable energy source and now that scientists have proclaimed Eureka once more the time is right to go all the way on solar with flexible colorful and high-performance peroxides thank you very much you

Channel: TEDx Talks

Views: 180,484

Rating: 4.7507138 out of 5

Keywords: TEDxTalks, English, Belgium, Technology, Chemistry, Science, Solar energy

Id: wkCmX24PRKE

Length: 16min 48sec (1008 seconds)

Published: Thu May 11 2017