![]() The more you spray, the more liquid you deposit and therefore in the dry film, the more solid you get. Now the spray coating is perhaps the one that everybody can relate the most to. So in addition to those, the quality of the films formed by this method, the amount of materials they use, the ink properties that are required for them to work successfully, there's also this issue in addition to the film quality of how wasteful is an ink form process and if we can control the wet layer. And then we have a technique called Spin coating that is a very, very useful laboratory coating method but that perhaps is not a useful method from an industrial point of view. There's also a technique called Slot die coating that we use, that has the slight advantage that you can actually control the wick thickness within a given range. When this dries, you get an even, ideal at least, an even dry film. We can just be pouring it over it or forcing it form a narrow gap between a moving web and a knife, thereby creating a liquid film that is of an even web thickness. That means that we are either spraying the material, the ink, onto the surface. So, if we focus on the coating techniques that form an even, homogenous layer, they fall in a few different categories. Most of the time we want the layer to be smooth and even or a well-defined thickness, but sometimes you also want a pattern etiquette. So make a coat, a painting, so the entire surface is coated with this particular technique. That means you cover the entire lateral plane. Now for the coding techniques, generally they are all zero dimensional. So in the surface plane of the solar cell, but also in horizontally, so most of the film foreign techniques they are in the lateral plane so they can be zero dimensional, one dimensional, or two dimensional. The coding or printing technique has what we call a dimensionality in the lateral plane. In its functional form, typically it comprises at least 4 or 5, sometimes 8 to 10 or 14 different layers, that each serve a purpose. Now, the coating techniques and the printing techniques, they can be divided according to their dimension areas the solar cell stack is a multi-layer structure. And in this first module, I'm going to go through coating techniques. So I'm going to run you through all those and the first distinction you make is whether it's a coating technique or a printing technique. And therefore, for particular ink, for a particular layer, this particular precision method That is the optimal one. I should also add at this point that perhaps the functionality of the solar cell in the end or of the particular layer that we are making in the solar cell state depends on both on the, also on the printing or coding process. And there are many, many ways of doing it. Ideally we want to do it in a roll to roll process so the foil isn't moving while we do it. So we're actually going to make those thin functional films using an ink, a solution, a liquid that we have to deposit on a thin substrate. And that is what, in the end, constitute a particular layer in your solar cell. You dry it so the material that's dissolved in this ink, this liquid, is left on the surface. Once you've formed the wet film, from the ink, using the method. The property of the ink is critical for the success of the application technique, so printing or coding technique. In this solvent you've dissolved your material that you need to deposit the layer of. It could be a chlorinated organic solvent. And in this solvent or it could be water, it could be an organic solvent. You need an ink, and the ink is a liquid. Before you start making your solar cells films, you need something. So the printing and coating methods used to form these thin functional multi-layer stacks. And in this module and the next one, we are going to focus on the actual methods we use to make them. Through the past few weeks you've been learning a lot about solar energy, a lot about solar cells, and in particular about solar cell that is, all our studies here are centered around the organic or polymer solar cell.
0 Comments
Leave a Reply. |