 Well, thank you, Richard, for that introduction. I'm happy to talk to you all today about reversible metal electrode deposition as applied to smart windows. This is a project we started in the McGee lab about a year ago and is now funded by the Precourt Institute for Energy here at Stanford. So we're looking at smart windows, which are windows that you can dynamically control the transmission of with a voltage. So you can control them from being clear to dark and switch them back and forth as you like. The main motivation here is for building energy efficiency. Buildings consume about 40% of US electricity consumption. And about half of this comes from lighting, heating, and cooling costs. People who study smart windows have determined that, on average, depending upon the climate and the size of your building, you can get about 20% energy savings for these lighting, heating, and cooling costs. So there's a big potential here for smart windows. Smart windows have been commercialized, but only on a small scale so far. And there's a few important reasons why that is. I'll talk about it in a bit. But in addition to building applications, you can think about some other applications, such as using these in the sunroofs of car windows or in switchable sunglasses. So most smart windows today utilize what are called electrochromic materials. These are materials that change color, essentially, when you apply a voltage. And these materials are incorporated in an electrochromic device. This is essentially a double pane window. And on each of the panes of glass, there's a transparent conducting oxide. Typically, this is tin-doped indium oxide, or ITO. And on one of these panes, you put down your electrochromic material, which changes colors. And on the other pane, typically, there's a counter material, which just accommodates for charge transfer when the window is switched. There's also an electrolyte in the middle of this device stack that facilitates ion transfer. So the most successful type of electrochromic materials out there right now are transition metal oxides. And the best of these is tungsten-6 oxide. This is a colorless compound. But when you electrochemically reduce it, it turns deep blue. Now, when this process is accommodated by lithium ions, essentially what you have is a lithium ion battery. The architecture is the same. But now you have this added feature of having a color-changing lithium ion battery. So why haven't electrochromic materials really been successful so far? There's a few problems. One is that it's very hard, it turns out, to color-tune these transition metal oxides. Tungsten oxide's blue. We'd really like a black material, so we can go from clear to gray to black. Another problem is these electrochromic materials work by absorbing light. And when they do that, well, they re-radiate heat, and so you lose out on some of the heat management there. They tend to be pretty expensive due to the multiple layers that are involved. You need at least four layers, and the commercial systems out there have maybe six or seven layers. And these are very difficult to scale up. They're typically deposited using sputter deposition, and this gets quite expensive to do on a large scale. Now, another big problem is if you want to switch your window, let's say once a day for 25 or 30 years, that already puts you on the order of needing about 10,000 cycles. And kind of the best lithium ion batteries in the world right now have cycle lives of about 5,000. And so this is a big problem. So when we got into this area, we wanted to pursue an alternative to electrochromic materials. And the idea we looked into was that of reversible metal electro deposition. Here on your cathode, what we're doing is we have some sort of metal salt dissolved in solution, we use water, and we're just gonna electrochemical reduce this to a metal on the surface of the window. Now you need a side reaction for this. Simplest thing you can think of is actually just taking metal that's on the frame of the window hidden and re-oxidizing it to that same metal ion. So your net reaction is just simply moving metal around electrochemically to turn it dark, put it on the center of the window to turn it light, put it back on the edge where you can't see it. The nice thing about this approach is you only need about 20 nanometers of metal to get a completely opaque window. This is good, but it also represents a challenge. You need to be able to uniformly and with nanometer level control, deposit a metal over the large area of a window. Another nice thing about this approach is that metals are reflective. And so you do a little bit better than the electrochromic materials in terms of heat management there. So I wanted to show you what kind of a typical device looks like that we construct in the lab. We start out with our cathode, which is just a transparent conducting oxide, like ITO on glass. And then we have our electrolyte, which contains our dissolved metal ion. Now our counter electrode is now just a non-conductive piece of glass, regular piece of glass, and there's now a metal wire around the perimeter of the window. So the first prototypes we've built first used copper and lead as the electroactive metals. Now we've moved on to using copper and silver because we don't want to use lead. Copper, electrolyte deposits very nicely and uniformly. There's a lot of work done on this metal. We throw in another metal like silver to make sure we have a black window, because that's what we want. So I want to show you what kind of the transmission characteristics are of these smart windows. This is an electrochemical cell and you can see that once we apply a voltage, this is looking at the transmission as a function of wavelength and time across the visible and infrared portions of the spectrum. Within a minute we can drop the transparency of this window from 90% to about 25%. And then we can go ahead and reverse the polarity of the electrode, strip that metal off of the surface and restore the transmission within another minute. So this shows that we have reversibility in terms of transmission. We also did another experiment now monitoring the transmission at one wavelength. So 600 nanometers, yellow light, running the deposition for a little bit longer, three minutes, such that the opacity drops to a 5% transmission. Then with no power consumption, we can hold the system there for 24 hours and go ahead when we want, switch the system and then it can stay transparent indefinitely. So this shows that these windows have good resting stability. We only need to apply power when we're switching the device. So the key actually to get all this working and I'm gonna have to skip a lot of the details, is actually depositing a thin layer of platinum on the surface of the ITO. This helps control the morphology of the metal deposit and gets something that's relatively uniform at least with respect to the wavelength of light. This helps increase the nucleation density of our electric deposit. We use platinum because platinum's electrochemically inert and we use a very thin layer so you can't see it. So with these systems, we can get very good cyclability. If we, of course, 1,000 cycles, if we don't include that platinum seed layer, the degrades very rapidly over time. And this is looking at the scanning electron microscopy and we can see that basically as a function of cycle number, the first cycle or after 1,000 cycles, our morphology is staying relatively consistent. So this was a good sign and again, something we didn't see without that platinum seed layer. It turns out this is uniform enough that actually what you get by eye is the formation of a mirror because we can switch this back and forth. We were calling it a reversible electrochemical mirror. We went on to, this was all in liquid electrolytes where I showed you, we went on to develop a gel electrolyte. This is better for device fabrication. You don't have to worry about these things leaking as much and if someone breaks your window, then you're not gonna get liquid all over the place. Challenge of this is that you've increased your ion diffusion with the increased viscosity. And so it turns out we figured out that the nature of how we put down this platinum layer becomes even more important. So the system that we've kind of settled on and optimized is putting a self-assembled monolayer down with an organic molecule on the ITO surface and then we have this style group that can bond to the platinum nanoparkals and that makes everything work pretty well. And right now we're able to cycle these windows more than 5,000 times. We haven't gone further yet to do that in the future. But this is with a copper silver gel electrolyte on a 25 centimeter squared scale. So I wanna show you what that looks like. What you're gonna be looking at is a piece of platinum coated ITO on glass and you're looking at the Stanford logo with a tree and there's a golf ball. Oops, let's see if that goes here. There we go. So now we're doing deposition on the surface of the window on the ITO glass. There's a golf ball with a Stanford logo there in the foreground. You can see the reflection coming in. And then we're gonna go ahead. This is wooden device. This is kind of the frame, just these prototypes. But now we're replating metal on the edge on the counter electrodes, which are hidden behind the frame, restoring the initial transparency of the device. The exciting part about this is one, we're getting uniform deposition on this kind of larger scale, 25 centimeters squared. And this was taken at cycle 1500. So we're getting uniform to even after cycling it a lot. So how are we doing compared to electrochromics? Well, we think we have an advantage because we're a reflective technology and by playing some optical tricks, we hope to be able to control whether or not we have a mirror or a black looking window. And if we're doing, can do that, then we'll be better than the colored materials out there. In terms of switching speed, we're competitive. We have minute or switching time on this scale. And cycle life, we're kind of right there with electrochromics, but we need to test this more. We think these materials, this approach should be a lot cheaper. One, we don't have all these different layers. We're not using a lot of platinum, so that won't be a problem. And we're only using one side of ITO, which is another expense. In future work, we'd like to understand the electro deposit morphology better, really do some good fundamental electrochemistry here. Control whether or not we have a mirror or like I said, a diffuse reflector, something that would be black. And look at how we can scale these up with some clever counter-electrode design and look at the cost. So in conclusion, I hope I've been able to show you today that we can uniformly and reversibly electro deposit metals for smart window applications. The key to this is controlling the nucleation of the metal on the ITO surface. We think we're doing very well compared to traditional approaches. And this is really a new project, so we're excited and think it has a lot of promise in the future. So thank you all for your time and I'd be happy to answer any questions you may have. What is your counter-electrode again without blocking the light? Oh, yeah, yeah. We're using copper wire. If you have copper wire, then your deposition will be expected to be probably not uniform because of the current path. It's not uniform on the other side, so how do you overcome that problem? Yeah, I mean, that's gonna be a problem. Eventually, we're gonna have dendrite formation after a lot of cycling. It's something we're aware of. Moving forward, we'd have to use some sort of inert scaffold and just have enough metal and pass it over to the other side. Over here, someone? Okay, let's thank Chris again. Thank you, Chris.