Quantum Dots , what are they? How they work and what their Applications?

Hello, this lecture is about ATS content. I mentioned contempt before, as an example of non-technological elements. Theme spots are very well known when talking about a technology and that is due to

their

fascinating application and color changing performance, which makes them very interesting. and interesting, but let's be more precise and see how

they

work

. The

dots

on condoms are nanoscale nanoparticles, or in other words,

they

are nanocrystals of semiconductor materials. They generally have diameters in the range of 2 to 10 nanometers, about 10 to 50 atoms. discovered in 1980 and show unique electronic properties intermediate between those of massive semiconductors and discrete molecules and once again I must mention that it is due to the unusual height of the surface-to-volume ratio of these particles and also to

quantum

confinement due to

their

number limited. of atoms and a special form of

quantum

dots

, the most apparent result of this is the most complete meaning, that is, quantum dots can produce distinctive colors determined by their size and tree, but how does it really

work

well?

I need to tell you a little about energy. level first if you remember we said that one of the quantum effects in the Nano world is quantization and because of that not all energies are allowed, that is true for individual atoms and I mentioned that the orbital shapes and also the atoms relate to the allowed energies, but in solid state. When we have billions of atoms, these orbitals connect the bonding concept into reality and so instead of a single energy level, we get a region of charge of energies called the energy band. In metals, these bands are continuous, but in insulators there is a noticeable gap between The energy bands of semiconductors remain in the middle have some band and are not as large as insulators, but there is still a way.

Look at this figure which shows in bulk semiconductor structures two important bands: the valence band and the conduction band. The valence band is the highest energy level and electrons. They have occupied it and the conduction band is the lower energy band which is empty and there is a gap between these two and this is called bandgap. Bandgap is a very critical parameter in many electronic and optical

applications

, in fact, and there is tons of research. to adjust the value of the bandgap, for example, if light is emitted towards some conductor, some electrons acquire enough energy to jump from the valence band to the conduction band and since a higher energy level is not favorable, after a while they may want to return to the valence band and they release the energy difference between the valence and conduction band yes, they release photons with an amount of energy equal to the bandgap and why does this matter to us because in Quantum mechanics energy is related to wavelengths, in fact, the different colors we have Look, there are different packets of photons with different wavelengths or let's say energy reflected from the surface of materials quite well, but

what

happens with quantum dots it has shapes of different sizes and is made of a limited number of atoms, so instead of energy bands we have some sets. of energy individual energy levels, but these energy sets are very close together, but still we have the band gap between the energy sets, interestingly depending on the size or let's say the number of atoms, band gap change and that is a good example of the quantum confinement effect. with the size at nanometer scale and you have realized that quantum dots of different sizes have different bandgap sizes, light hits them and then the electrons return from higher energy arrays to lower energy cells, they release different amounts of energy, which implies different wavelengths and different colors. the smaller the size of the quantum dots, the larger the bandgap, the more energy is released, the higher the frequency and we get a more bluish color, vice versa, we get a more reddish color.

Very well, semiconductor dots or nanoparticles were terrorized in the 1970s and were initially created in the early 1980s for their artificial nanoparticles, so my conductive nanoparticles despise dots are artificial nanostructures that can possess many varied properties depending of its materials and shape. In reality, the properties of quantum dots are not only determined by the size but also by the composition and structure of the shape, for example. Is it solid or hollow? The size and composition of Unix. The tunable electronic properties of these nanostructures make them very attractive for a variety of

applications

and new technologies, such as electronics, such as single-electron transistor optical applications, such as television displays, solar cell information storage, imaging medicine and even detection.

Let me show you some of the examples of content dot quantum dot televisions and show the most common use of quantum dots today can be TV screens. Samsung and LG launched their contem dot LED TVs in 2015 and few other companies followed shortly after contemn. Due to their unique physical properties, they will be at the center of next-generation displays compared to organic luminescent materials that use organic light-emitting diodes or LEDs. Contour-based material has pure color, longer life, lower manufacturing costs and lower power consumption, another key advantage is that because drivers can be deposited on virtually any substrate, you can expect printable content.

Flexible and uniform that shows everything, so it's great. Another example of quantum dyes is a biological and chemical application. Quantum dots are also finding important medical applications, including potential cancer. Treatment quantum dots can be designed in such a way that they can accumulate in specific parts of the body and deliver anti-cancer drugs attached to them. The big advantage is that they can target individual organs such as the liver. precisely than conventional medications, reducing the unpleasant side effects that are a characteristic of traditional non-targeted chemotherapy. Condoms are also used in place of organic dyes in biological research, for example they can be used as nanoscopic bulbs to illuminate and color specific cells that need to be Assad Eid under a microscope, they are also being tested as a sensor for war agents chemical and biological, unlike organic dyes that operate in a limited range of colors and degrade relatively quickly.

Contemporary dyes are very bright and can be manufactured to produce any color. of visible light perfect that is the end of how much that lesson see you next time take care