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카테고리
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학습트랜스크립트
00:00안녕하세요.
00:05안녕하세요.
00:08안녕하세요.
00:10안녕하세요.
00:1210 days break almost.
00:16I thought it never ends,
00:19but it's almost ending.
00:22As I promised in the class,
00:25I will record this PV part
00:29because we have a break
00:31and also we are not going to have a midterm exam.
00:36So when you have time,
00:38you take this class
00:40and then prepare the summary for PV history
00:47and each solar cell
00:50and Dyson-sized solar cell
00:53and others.
00:54You will have a few things
00:57in this whole class
00:59and then you prepare at least
01:03two homework summary
01:05based on this whole set of class.
01:11It's quite long story
01:13and I will prepare A, B, C recording
01:19and this is the first one A
01:22and then B, C, 2.
01:25Then you want to make that summary
01:30for each A, B, C
01:33and just two of them.
01:38You don't have to submit all the summaries.
01:41Just two summaries will be enough.
01:44You decide which one you will go through.
01:50Okay.
01:51We already saw this kind of images.
01:54So let me start from the next slide.
02:00Briefly,
02:02PB history is a long history, long time history.
02:09There have been a lot of stories
02:12like some big money things.
02:23So a lot of people try to make money from the solar cell
02:27and then also many companies broke down.
02:32So although they are generating the energies we really need,
02:40it's not like that easy one to make the whole devices.
02:44We will see.
02:48Okay.
02:49Let's start the PB history part first.
02:54The first one is a photovoltaic effect.
02:59Does this slide remind you of something which is very close to photovoltaic effect?
03:07Like a photoelectric effect.
03:10Right?
03:11So some photoelectric effect or photovoltaic effect,
03:18some sort of the solar light can be converted to electron related something
03:27or some other energy changes from one thing to the other.
03:36You know, Einstein got a Nobel prize for this,
03:40like what is that?
03:42Like the photovoltaic, no, photoelectric effect.
03:47So threshold energy something, right?
03:51We will see this photovoltaic effect first.
03:54Do you know like when that Nobel prize started?
03:58It's 1901.
04:01Let's take a look at this guy.
04:07He died like 1891.
04:10I think a photovoltaic effect is also very important thing.
04:13And if he was alive on that up to 19 sometime in some years,
04:23then he might also have gotten some Nobel prize.
04:29And he could be a Nobel prize winner.
04:32But anyway, let's take a look at this one.
04:36The photovoltaic effect is the process of converting light into electricity,
04:43which is the principle behind the solar cell layer.
04:48When photons from light, light strike the material,
04:56they energize electrons causing them to move and create an electric current.
05:03But in this case, they didn't measure any current.
05:06That's going to be shown in the later part by Dyson-sized solar cell by Grezel at EPFL.
05:14He got a lot of money for that stupid solar cell.
05:19And then this is achieved in solar cells by using a semiconductor material later,
05:27like open silicon, which has been treated to have two different layers.
05:36I will explain that like PN junction in the later slides.
05:40And you will see the basic theory for making some solar cell device later.
05:52But in this case, he used only silver halide coating.
05:56Silver halide is not a conducting material, but it's very sensitive to light.
06:05And in the case of chemistry, we also learn some silver mirror reaction that causes silver halide.
06:17And silver halide is not much soluble in water.
06:22So if we have this material on the surface of some paper or whatever,
06:29they do not dissolve onto the liquid.
06:34So here, he's like, I'm sorry, I have to explain, introduce this guy first.
06:42Redmond Becker, he's a French physicist.
06:47So I think we have to read him like Edmond Becker, something like that.
06:54In photography area.
06:56So he is kind of, what is that photographer?
07:02I think photography area.
07:04He studied the solar spectrum.
07:14Very interesting, solar spectrum.
07:17Long time ago.
07:19It was like almost, what is that, like 200 years ago?
07:23Or no, not that long, like 150 years ago.
07:27And some kind of magnetism, right?
07:33Electricity.
07:34That's quite interesting, right?
07:36Because I can't imagine this light is consisting of some sort of magnetism and electricity and related to some kind of optics.
07:49That's pretty quite heavy, tough subject we have to learn about.
07:56So I'm not good at it.
07:59I don't know much about it.
08:01So we will skip some of the basic theory part for this solar and some magnetism or some optics part.
08:14But he, like 1939, see this one?
08:20He discovered this apparatus.
08:24He made this kind of apparatus in 1839.
08:29Oh, how long?
08:31He was only 19 years old.
08:34He was born in 1820.
08:37And he made this kind of thing when he was only 19 years old.
08:43Isn't it?
08:44Isn't it?
08:45Isn't it?
08:46Isn't it?
08:47What is that?
08:48Like, um, the genius?
08:53But, um, you know, we have to know this one, too.
08:58Like, um, he, uh, he invented, uh, this kind of things.
09:04But he also very famous for a luminescence and a photo of a phosphorescence.
09:11You know, he was the son of some Antoine César Baccarat and the, what is that?
09:22Henry, Henry Baccarat.
09:27So, you know, they are, like, very famous for, like, radioactive activity research.
09:37So, his family, like, parents are all scientists.
09:42So, maybe they might help him, you know, work on this kind of experiments.
09:48Because, uh, his parents is also working for the solar spectrum radioactivity.
09:54Right?
09:55So, I don't know, he really, uh, discovered the whole thing by himself or his parents helped
10:02him.
10:03But anyway, it has been discovered by this guy in the, in the history.
10:12So, let's see the next one.
10:13This guy is also 1828.
10:17So, like, eight years later than the, the, the first Edmund Baccarat and, uh, the United
10:25Kingdom and Electrical Engineering and, uh, Guttapacha.
10:30Guttapacha is kind of a, some plastic material.
10:34The, I think, um, it's a real material thing.
10:40But I think it's also kind of a company.
10:43And he works at this kind of company.
10:46And then he, uh, had to make some sort of wire, um, from the United Kingdom, the England,
10:57to, uh, France.
10:59You know, they have a sea between, uh, the, between those two countries.
11:05And then when they have, like, um, uh, phone system, they have to have some sort of electricity,
11:12a signal, the wire between two countries through the, under the sea.
11:19Right?
11:20So, uh, he had, he has been using a lot of material to send, uh, the, the good signal from one,
11:28one country to the other.
11:30Then he was treating a lot of material.
11:33And then also that has to be covered with, like, a plastic.
11:37And, uh, and then, you know, the, the under the sea, they should have some sort of, what
11:44is that, like a cave to, uh, bury that big wire for the transport.
11:51The, the signal transport.
11:56So, um, you know, at the end of the, the cave, the, uh, under the cave, it's quite dark.
12:05And then that interface or the gate, it was not dark.
12:11So, um, he used a lot of material and then he figured out this selenium, amorphous selenium,
12:19shows, shows some weird signal, depending on the light.
12:24Uh, so, uh, he reported this kind of, uh, conductivity changes under the, uh, the light, or depending
12:36on the, the, the, the existence, the existence of the light.
12:40When it's dark, it doesn't show any conductivity.
12:44But when it is like a little bit bright or under the sunlight, it's, it shows some sort of conductivity.
12:52At the very beginning, he thought it could be some, it could be contaminated by some other material.
12:59And then later he figured out that the, the pure selenium shows that kind of characteristics.
13:06So, he reported this, uh, this phenomenon to nature.
13:11See, nature, that's everyone's dream.
13:16It, it's published in 1873.
13:20That's quite a long time ago, right?
13:23Um, at that time, they didn't have any impact factor for this.
13:28And then also they do not have that many, um, the journals.
13:35So, and also, you know, this is it.
13:39They, they wrote only this amount.
13:42It's like a newspaper for science.
13:47Um, but anyway, he did.
13:50And then the, a lot of scientists like tried to figure out why this happens.
13:58So, you know, it was a long time ago.
14:02It was only, what was that?
14:04And it's, uh, oh, 1873.
14:0817, and then the next year, James Clark Maxwell.
14:12Then, uh, selenium effect sent an email to Peter Tate.
14:19And, uh, that's mathematics for the calculation.
14:23And then finally, like 1876.
14:26Simple, uh, sample geometry used by Adam and Day for the investigation of the photoelectric effect in selenium.
14:35So, they made some vacuum thing to, to remove any kind of, uh, the other, the side effect.
14:46And then, uh, they figured out it's really happening under the light.
14:52And then, 1883, some Charles Fritz makes a solar cell structure with efficiency around, like 1%, selenium.
15:03And then, selenium meter.
15:06Like 1%, do you think this is enough for the power generation?
15:12So, yeah, he made it, but nobody remembers his name, like Charles Fritz.
15:18Do you, do you happen to know about his name?
15:23No, it's not on the textbook either.
15:26But anyway, he made a solar cell only like 1% efficient.
15:32So, and then finally, there has been, um, here assembled in, on the roof of some building in New York City somewhere.
15:47So, uh, the picture has left by now, but, you know, the, nobody knows what building it was, uh, built at.
15:59But, I think somewhere, we don't care much about.
16:03So, uh, this is the solar cells.
16:06It looks, uh, quite large.
16:08Right?
16:10Compared to other, the roof.
16:14And that looks quite large.
16:17And it say, let's 1%, 1%, 1%, 1%.
16:21That's not that big, uh, big power.
16:24But, you know, by the time, they didn't need that much power either.
16:29So, uh, small amount of power generation might be enough to, um, show something.
16:36I don't know what he, um, has had shown with this kind of energy saving, but something.
16:49Okay, uh, and then the, uh, photoelectric effect.
16:54See, like 1887.
16:57And Einstein also discovered the quite important thing.
17:02Right?
17:03So, the photoelectric effect is the emission of electron, right?
17:12Photo, like, photoelectrons from a material.
17:16When light of a sufficient, the high frequency shines on it.
17:22Demonstrating light's particle nature.
17:27A minimum threshold.
17:29Remember that minimum threshold.
17:31We need the, not, not just the, like, quantity of the light.
17:37We need, uh, some sort of high energy.
17:40Just one photon is enough to emit one electron.
17:45But, if we do not have, uh, low energy for the light,
17:51the bunch of light cannot, uh, emit any electrons.
17:56So, it has to be, like, high energy enough.
17:59That's called, like, threshold.
18:02So, a minimum threshold frequency is required.
18:06And, uh, exceeding this frequency determines the kinetic energy of the, uh, the ejected photoelectrons.
18:16With the number of ejected electrons, depending on the light's intensity.
18:22So, once the energy is enough to heat the electron out.
18:27Then, the amount of electron is, uh, uh, related to the amount of electron, uh, uh, the, the, the, the intensity.
18:37The, uh, I'm sorry, the other way.
18:39So, the amount of electron emitted from the, the material is related to the amount of the light intensity.
18:48Right?
18:49Correct?
18:50So, this phenomenon supports the, uh, the concept of photons.
18:57Later, this is, the information gave a lot of things, uh, to improve the solar cell efficiency,
19:05and then solar cell materials, semiconductor, everything.
19:08You know, I have to introduce this guy again, like, uh, Heinrich Rudolph Hertz.
19:17I don't remember, like, Heinrich Rudolph something, but I remember Hertz.
19:23That, what is that, like, um, the rent car company name.
19:30And also, like, uh, we are using Hertz a lot.
19:34In, in our country, that, that DC, the 220 volt, and then 60 Hertz, uh, the, the current, the indirect current.
19:46So, uh, hmm, he's very famous, I guess.
19:52And, uh, you know, do you think he got a Nobel Prize?
19:57It's very important thing, right?
20:00But he never received a Nobel Prize.
20:03Why?
20:04Because he died in 19, uh, 1894.
20:08I mentioned that Nobel Prize started in 1901.
20:12So, uh, you know, the, to get a Nobel Prize, they have to be alive by the time they, uh, give the Nobel Prize to the person.
20:27So, um, you know, Edison didn't get a Nobel Prize either.
20:33However, he, he is a kind of a bad person, right?
20:37He took advantage of Tesla a lot.
20:42Uh, but anyway, he got a chance to get a Nobel Prize, but he couldn't get one.
20:48But he, he didn't get a, he didn't get any Nobel Prize either.
20:53Then his groundbreaking work on these electromagnetic waves, however, was, like, found foundational to many technologies,
21:06and earned him immense, uh, the, uh, the, uh, human, uh, recognition, including the unit of a frequency, the Hertz, being named in his own.
21:21Um, you know, in Korean, we have, uh, uh, ho-sa-yu-pi, in-sa-yu-myung.
21:28Do you know the, uh, that words, like, ho-sa-yu-pi?
21:33The tiger lives in his skin. In-sa-yu-myung.
21:37And, uh, human being leaves his name to the, uh, next generation.
21:43Um, I know that's quite important, but, but that's not everything we have to go through, right?
21:52Um, so, um, it's an honor.
21:56Um, that's a lot. Sorry. That's it.
22:01Okay, and then dye-sensitized solar cell.
22:061873, after that.
22:10This guy, like, uh, Bojell, and, uh, if we say dye-sensitized,
22:16then the greater is quite the famous guy, too, EPFL.
22:25Uh, I don't know, like, he has to be retired by long time ago,
22:30but I think he's still working, uh, in that school,
22:35because he got a, got a research fund fund from almost every country.
22:41So, you know, like, EPFL gets a lot of money from outside.
22:46So, I think he's still there.
22:49Uh, he was also, uh, the candidate for the Nobel Prize,
22:55like, Gretzo, for dye-sensitized solar cell.
22:59But he didn't get one by now.
23:02And, uh, um, these days,
23:07not many research people are working on dye-sensitized solar cell.
23:11And then they figured out it's never gonna be like regular solar cells.
23:17Although it has a lot of advantages.
23:20That might be why he didn't get a Nobel Prize yet.
23:25And, uh, the extended one is, uh, like, uh, the perovskite solar cells,
23:30which is very close to dye-sensitized solar cell.
23:33And then we will talk about that in a later part.
23:37But anyway, so, uh, he has this kind of a structure.
23:42And, uh, the titania, uh, on some conducting,
23:48transparent conducting oxide layer.
23:51And then some sort of electrolyte inside.
23:54And, uh, the, the electric device is fabricated by this way.
23:59But actual device is made by Gretzo.
24:04Not by this, the Fogel.
24:07This guy just figured out the, just regular titania surface.
24:15And then he applied some sort of, like, the dyes from flower.
24:21For example, the rose or some other, uh, flower-related dyes.
24:30And then he applied that dye on top of this one.
24:34And then when they applied the, the, when they shine the light,
24:38they figured out some electrons are moving from one side to the other.
24:43So yeah, that, that, those are five guys, uh,
24:49like a quite important jumping from, um,
24:53from very beginning and to the real solar cell device.
24:59And then finally, 18, uh, 88.
25:04This guy, the Edward Weston, got a first U.S. patent for solar cells.
25:14You know, this is the first, uh, the, uh, the patent work.
25:20And, uh, he, he's an American, but he was born in, uh, the England.
25:26And, uh, some transformed radiant energy derived from the sun into electrical energy.
25:34Or through electrical energy into mechanical energy, something.
25:39You know, he got this patent, but, you know, like a patent is effective for around, like, 20 years.
25:49So, he discovered it too early to get real money.
25:54Maybe he got, uh, some research fund to work on, but that might be it.
26:04After that, you know, here, Albert Einstein publishes photoelectric effect on a quantum basis tool
26:11to celebrate Korea University Foundation, you know, 1905.
26:19Then 1921, he got a Nobel Prize.
26:23And, uh, the, you know, crystal silicon.
26:28Yeah, Jan Chukurelsky, this guy is quite famous, right?
26:33Like a Russian guy.
26:35And that ingot, silicon ingot, which has a very high crystallinity through that.
26:42So, he can make, we can make some, the wafer through this crystal silicon ingot.
26:48So, that, that research started almost 100 years ago.
26:55More than 100 years ago.
26:57And, uh, 1932.
27:01Some other birds and, uh, Stora.
27:04Cardium selenide.
27:06This is also important material for, uh, window material.
27:11For, uh, solar cells.
27:14And, uh, 1950s, Bell lab.
27:17Now, Bell lab is working on this kind of electricity semiconductor work.
27:23And silicon space activities.
27:26And silicon practical cell with 6% efficiency.
27:30You know, currently silicon solar cells shows, like, over 25 and 26, sometimes 27% around, uh, efficiency.
27:40That's a lot of improvement.
27:43The, uh, limitless energy of the sun.
27:47They realized this one here.
27:50In 1950s.
27:52And then this company, Hoffman Electronics, make, like, 2% efficiency commercial solar cells.
28:00That's $25 per cell or 1,785 per watt.
28:09That's ridiculous.
28:11This is a small cell.
28:13And then this is a large cell.
28:15That's only 2%.
28:17Stupid.
28:18And then, uh, Hoffman Electronics, finally, 9%.
28:23Satellite Vanguard 1 launched.
28:26And Soyuz, et cetera.
28:32This is Vanguard 1 with a solar cell.
28:35You know, can you imagine how large this, like, this, um, the, um, the space.
28:40Um, the space solar cell could be.
28:42The actual size is only this way.
28:46So, it's, the communication between this Vanguard and the Earth, the ground system has been lost.
28:55So, but still this Vanguard 1 is running around this space.
29:01If somebody can get this one, uh, he will be like a millionaire.
29:06But I don't know anyone can try to catch this one.
29:12So, you try.
29:14And you get a lot of money and then share that with me, okay?
29:18Because I gave this information to you.
29:20Um, but you get, you need to get a lot of information about this.
29:27Because I don't know it's still running around this, uh, the space orbit, orbit.
29:33I don't know much about it.
29:35But you know, like a solar cell is located down here, here, only small area.
29:42Uh, I don't know that's enough to save the energy to send the signal to the Earth.
29:51And then also, if they have some sort of like battery system inside to charge and recharge.
29:58And, uh, that may not work properly.
30:01Because, uh, it's, the after service, the period has been gone.
30:10Okay, it launched on March 70th of 1958.
30:17And communication lost in 1964.
30:21Still in orbit.
30:22We see, like a hundred, hundred centimeter square.
30:27That's still in orbit.
30:30Let's go and get it.
30:33To be a millionaire.
30:38We have to find out the, uh, where it could be.
30:42At, by some sort of simulation.
30:46We have to launch them this day.
30:48And then, where that, the last signal was on this sometime.
30:53And then, we do some calculation or simulation to figure out where that, thank God, is excited to get one.
31:04Then, later, like a David Carlson and Christopher Ransky and the ICA lab.
31:15I'm of a silicon photovoltaic.
31:17But the, the previous one is a crystal one.
31:20And we have to make some sort of, what is that?
31:22Vapor.
31:23But this one doesn't need that vapor.
31:26So, but very low efficiency.
31:30And Solar Energy Research Institute in Colorado.
31:34That's, uh, CERI.
31:37And then, uh, production of 500 kilowatt with a silicon solar cell.
31:43And the first solar powered what?
31:45Do you remember this?
31:46This calculator.
31:48I'm sorry.
31:49And, uh, later Dyson State Solar Cell and NREL Solar Energy Research Facility is established here.
32:00NREL 1993.
32:02So, this is a very important institute in the, in the United States.
32:08They are controlling all the renewable energy.
32:11The whole thing.
32:12You know, DOE gives money, uh, to this NREL to control the energy, recycle energy related project.
32:21Then, the money is controlled by some, what is that?
32:26I don't remember the exact name.
32:28But they have certain system to run the money for the research.
32:32Okay.
32:34This is the, uh, the, uh, the end of part A.
32:38And then, I will go through this, uh, like a semiconductor theory for the part B.
32:44Okay.
32:45Thank you for your, uh, kind listening.
32:49If you have any questions, you can send me an email.
32:53Okay.
32:54Thank you.
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