Science & Technology | Quantum Dots | UPSC | VIZAG IAS ACADEMY

Added: 2026-06-05

[00:00:00]Next topic that we have is quantum dots.

[00:00:02]Again, very important material coming from the nanotechnology. You can imagine a product or a material when you reduce its size on a nano scale, let's say from 2 to 10 nanometer. And what is a nanometer? 10 raised to power minus 9 meter. Extremely extremely small. 1 billionth part of a meter. So, once you reduce the size, once you reduce the its properties change.

[00:00:27]Its physical property change and sometimes chemical property also change if you are do some tweaking. Here we are talking about the increase or basically changing the physical property just by reducing the size. So, what happens when you look so we take cadmium.

[00:00:42]We like cadmium compound. When you reduce the size of it up to 2 to 10 nanometer, it starts emitting light of different colors.

[00:00:54]That is the property of These are called quantum dots. They are so small, so tiny and they emit different lights. Look what happens. Because we are reducing the size, so this area for the electrons to move is actually reducing. So, once you throw light on them, they they get excited and they basically jump from one orbit to another orbit because they are excited. But after some time, they lose their energy and they come down. And when they come down to become stabilized or to to go on the original orbit, they emit light with different wavelengths.

[00:01:28]These are the lights we are talking about here. So, if you reduce the size of cadmium, this is how this light is generated. And if this light is more, they will generate blue color light. And if this energy here is less, they will reduce and basically release red color of from the quantum dots. So, they basically change their color by if you provide them energy, let's say through sunlight or by some other microwaves.

[00:01:53]This is how it is done. Now, where they are used? They are used for the imaging purpose. Imaging of human body let's say.

[00:02:02]So basically if somebody has like say cancer so we can use quantum dots by identifying the cancer cells because these are quantum dots are going to release different color of energy. We can map a human body where cancer cells are. So we can use it for the imaging.

[00:02:19]We can also use in the space technology also for the medicinal purpose also or for any sort of imaging quantum dots are done and these days quantum dots can be used in the electronics as well. We have QLED quantum based LED which is also used in the displays very high quality displays.

[00:02:37]This is what quantum dot is.

[00:02:39]What is the problem then? Problem is toxicity because cadmium is very very toxic and and basically that is why we don't use it that much but in future if you develop another materials which are safe to use so quantum dots can be used in on a much larger scale in that case.

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