A Solar Cell From A Broken LCD Screen - Part 2 - Recovering Indium

[Music] so in a previous video solar cells of an LCD screen we took an LCD screen from an old monitor absolutely two pieces right to its bare-bones and this is the stuff we got now there's an awful lot of stuff in a monitor and there is a growing industry and the reclamation of them but still mostly people are just throwing them away and for the want of something like 10 or 15 minutes of effort you can get some brilliant bits and pieces so as part of the backlight you get a big lump of this this is acrylic 8 millimeters thick a4 sheet of this on these days that's your a4 it's about 10 quid so you're probably talking about 15 quids worth of acrylic right there that'll do some nice project boxes especially if you reclaim half a dozen of things like I did and I've got a massive stack of this I'd took me about half a day to do it I think to do all of those then you have got a massive stack of it worth about a hundred quid or so which I thought was awesome the other thing you find really of interest in it is this thing no this is a kind of for now lens actually call it prison for prism film but it's also known as a straight line for an hour and if you rub your finger line you'll feel the ridges and those ridges are little prisms and what this does is focus the light onto the screen so you get unidirectional light now apparently I haven't tried it but apparently if you stick this on top of your solar cell what it does is it takes the incident light and lights coming in that way and bends it and forces it through the solar cell at parallel to the surface so there are reports of sticking this on solar cells and getting an energy efficiency improvement just by putting a layer of this on well worth a try I might give that a go sometime but well worth a try now there are two kind of Fornell lenses this linear one and then there's this kind which is called a spot believe you run your finger you'll feel that the ridge is a circular what this does is create a focal point and this is the stuff that people are using to burn words that kind of thing this will not create a focal point because they're ridges at Alinea but it will bend the light so that it enters your solar cell straight away even if the lights coming in in that direct that means it's going to or certainly the research is saying but it certainly should make you solar cells more efficient because you have to capture all that light from around that you weren't capturing before so that's massive sheets of that so well worth getting these are the bits and pieces the thing we were concentrating on were these two bits this is the actual backplane and this is where all the electronics have been printed then this darker one this is the front plane this is the one that you look at when you're looking at it now they are made differently this one the backplane is basically a massive pile of MOSFETs massive pile of transistors and then you suppose to be able to get generation from any bit of silicon if you shine a light on it if you take the part a 2 n 3 or 5 5 5 shine a light on it you will actually get it to generate about half a volt 20 30 milliamp something like that if there's any interest don't do a video on that showing you had to chop that up and make that into a generator but unfortunately these are metal oxide semi conductors so what may that means is that the silicon N and P Junction are not in direct contact with them so you can't just shine a light on this and hope it's gonna generate because it wants that to be honest that's a bummer but it's also the way it is and that the surface of these actually looks like this as you can see actually pretty complex and it takes about seven or eight passes to place that on and at the end of it what they do is they put a layer of poly imide on to protect everything so this has got a plastic layer on it and if you actually try to take the resistance of that to see what kind of conductivity it has been absolutely jack huh you can't get that to conduct across that plane that's obviously a bit of a shame but that's the way it is this one what they do with this one is put a black mask on it and then print red blue and green cells and it looks like this after they've done that what they then do is they print the idea on the top of that so right on the top of there is a layer of indium tin oxide and if we test the resistivity again we'll just pop that onto that surface sure enough we get conductivity is about 3 ohms as well something like that that's because the indium tin oxide which is a big layer on here is sitting on the top the indium tin oxide on here is sitting underneath the poly imide there's much much more i teo on this one then there is on this clear one so it's a question of how to reclaim it now there's an awful lot of work going on on reclaiming this stuff because indium is scarce and getting stupidly expensive what they normally do is grind these up they grind them up and then they give them a wash and use a chemical method to actually collect them and we're gonna do something very similar this glass incidentally that this is on also is actually really expensive glass it's not normal glass it's an optically pure glass of the low sodium content so try not to break them as you separate them but if you do break them don't throw them away cut them into little squares with the glass cutter and keep those squares because those glasses that you've created actually have quite a lot of value and will in themselves cost you a lot we're going to obviously do something and recode that glass if you don't you have to buy that glass the nearest thing you can come to is a microscope slide and they're actually quite tiny so even if you get a broken bed you're still gonna getting a big chunk of glass out of there and that glass will actually be quite expensive for you ok let's have a look at this one first what we're gonna do with it is remove the pollak image coating the polyamide is unbelievably tough it's captain really fast and tape is polyamide and the same thing here lasts up to about 400 degrees C so you're not gonna be able to burn it off because you're gonna crack your glass and you're gonna ruin everything else about the only way is to take it off mechanically like I said what they normally do is grind this up incidentally if they grind both of these up per kilo of ground-up material has about a hundred grams of india minute that's a lot of indium but we're going to do a mechanical method to remove that polyamide coating now it is tough and the adherence is tough oh I'm gonna do is take this the carpet knife blade and go over the top and you go over the top actually much harder than you'd think it's quite hard and as you take off the in mind you will be able to see through the glass it'll go from a kind of yellowish color to a much more see-through color I'm gonna do that and get back to you okay put it on a white background because I'm hoping this will show up for you that bit I haven't even touched if I take my blade you can see the poly in my coming off as those dark spots and we've got a change in the color there don't you get that little bit off you can use a fine grade sandpaper and even that out and then we can check the conductivity so on the bit next to it as you can see it's very resistive and on that bit there it's now conductive so when you've been over that whole thing then he will end up with the sheet of conductive glass in which case you can build something like a dye sensitized solar cell lots of videos on how to build those dead simple 10mm dioxide on your conductive glass suck in blackberry or raspberry juice on your other piece put a bit of carbon put a bit of triad I didn't there slap them together and you'll have a dye sensitized solar cell so you can use that piece of material to make yourself a dye sensitized solar cell the bit I'm actually interested in because honey chemist is this bit here and this bit here like I said is conductive already because the idea was on the top the only shame about the answer is it's so great now it does have transmittance I can see through it it's actually kind of cool because it breaks things up into the primary colors and but it's a bit too dark use as a solar cell just like that and there's an awful lot of indium tin oxide on there it is mixed up with other stuff but it's on there now if we were to crush this up we could process it but we would lose the glass when the glass itself like to say has great value but this stuff comes off much much easier and all we have to do is scrape this off and collect it so this stuff scrapes much easier you just take your knife to it and all that dust there that's what you want to collect so at the end of that what you end up with is this beautiful piece of optical glass now we are going to extract the indium and recursed it with indium tin oxide because we don't want the color screen but you don't have to do that and that glass actually is a specialist material and again another one of those stupidly expensive things if you want to buy a square to experiment with but this could be used for Seiler coating with an aluminium tub sink oxide and I have done videos on doing that I can't remember the names right now to search through and you'll find the a Zed o coating method along with showing you how to make a cylon machine so that you don't have to do the boring bits do you don't have to put the indium tin oxide back on now you could put a cheaper coating on like aluminium dope zinc oxide and that's well worth the experimentation but indium tin oxide is stupidly expensive you can get a good SL coating you're gonna make much much cheaper solar cells so we get that which is well worth having and well worth experimenting and we get this which is about point three one grams of a mixture of resins and indium tin oxide and we're going to use a method to extract that now the method were using actually is in fact an industrial method I'm just scaling it down so we can do on the tabletop but it's the same method that's used in industry if you want to do an awful lot of this and reclaim the indium obviously scraping you off a piece of glass is going to be a real chore for you we want the glass I want the glass which is why I've tried to protect and save the glass if you just want the indium all you have to do is break this up into small parts and go through the next steps and you'll be able to reclaim the nd amount of LCD screens no trouble at all it's actually quite easy and you'll find that in a minute if you want just the glass to do the different coating by all means do a different coating is that Oh wonderful if you want something that will do the job see you can make something like that dye sensitized solar cell we did that earlier in the video where we just took the back screen and script the plastic off you can use that so it's a whole lot of things you can do here depending on what it is that you want to do obviously I'm really interested in the entire process so now we've got our optical glass we can put that to one side and save it along with all the other optical glass and I now have about 400 pounds worth of this just for the effort of scraping for a couple of minutes and then we can get on to extracting the indium out of this now when you read about how they go about reclaiming the indium out of these things what they tend to use is concentrated sulfuric acid that's hot and let's face it nobody wants to go mucking around with that especially in the kitchen table top but there is an alternative and the alternative is this what this is is a 1/2 molar solution of this stuff oxalic acid Oh bar keeper's friend now oxalic acid does some weird and wonderful things that are just tremendously helpful for Indian Hindi amande tin extraction all we actually do is take the stuff we scraped off the glass and chuck it in there stir it and give it 45 minutes at 70 degrees centigrade and it will recover a hundred percent of the indium okay so I'm just going to add that get it boiling and filter it so I just filtered out with the coffee filtering you can see the resin muck left in the filter and here is our beautiful indium solution is kind of gonna color a greenish color there are no organics in it its water so it's the indium and tin in there making this this color now what's really cool about using oxalic acid is it wouldn't leave this between two and five days so five days to set it to one side any impurities in there are going to precipitate out and that's just really bizarre it's not so important here because obviously we just put in resin and indium tin oxide so pretty much all that's in there is the indium and the tin but if you crush the glass you will get some leaching of aluminium and some silicon going in there as well um and you can't stop that and if you lose that leave that like a say for five days they will precipitate out as a white precipitate and you can just refill through it again at the end of five days and you'll have a pure indium tin of sumit acid mix and those Y precipitates are all of the other junk that just just falls out of this particular solution that's really really useful obviously and that's one of the curious things about oxalic acid the other thing of course is I can get quite close to without being scared because it's not boiling sulfuric acid so that's really awesome as well now the solubility of the indium is dependent on the concentration of the serve the oxalic acid so once you've got those precipitates out what you do then is double the concentration so add another half mole of oxalic acid in here and then the indium will precipitate out and all you have to do is filter it to recover it now is about a hundred percent indium recovery from this muck in here will lose about one percent in that participation process to get rid of the impurities but we'll get a 99% yield out of that once we increase the concentration that's really awesome now it is a lot of information to cover I understand that because we have done a lot in this particular video this particular process what I'll do is I'll put the reference to the paper in the description so if you want to know more about this process have a read at that paper it will tell you everything you need to know about it if you're thinking about reclaiming indium as a possible business I'll go for it I mean you know it's a really sense of thing there's a ton of this stuff kicking around Indians a good price and it's to be honest dead easy to do you better get the screen crush it up wash it in some oxalic acid and filter it piece of cake that's really good so we've covered quite a few things here we've covered reclaiming the back panel and turning it into a conductive glass just by scraping off the poly your mind so that we can use that in things like die sensitive solar cells we've recovered the optical glass from the front panel but again just scraping that stuff off and then we can use that glass by cutting it ourselves with the silo method to make that into another conductive glass that we then can use as solar cells we've also recovered the indium which itself could be an entire business and then once we've recovered that indium what we need to do is obviously cut it onto some of the optical glass to make yet another kind of conductive glass that can be used in solar cells now the process of covering this in indium tin oxide is really quite simple actually you get a hot plate at 400 degrees centigrade pop your glass on there and then uses an airbrush and spread this liquid onto it and it will just burn off leaving you indium tin oxide anyway that's a lot I hope it was of interest I hope you enjoyed the video and thank you very much for watching

Channel: Robert Murray-Smith

Views: 48,652

Rating: 4.9198828 out of 5

Keywords: indium, precious metal, metal refining, metal recovery, solar, DSSC, conductive glass, lcd, robert, fwg, murray-smith, metal, refining, metals, recovery, conductive, glass, energy, panel, cell, power, green, alternative, technology

Id: AvXTnvT8WNo

Length: 17min 19sec (1039 seconds)

Published: Tue Jun 23 2020