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Quantum dots are making waves in the world of TVs and monitors, but what exactly are they? Is this just another abuse of the word “quantum” by marketers, or are these points as amazing as they sound?

the artificial atom

Quantum dots are particles of semiconductor material a few nanometers in diameter. Also known as “artificial atoms” (despite being much larger than an atom) these dots act similarly to atoms in their relationship to electrons. They are so small that their electrons are “trapped” and they behave similarly to atoms. When ultraviolet light hits a quantum dot, its electrons are raised to a higher energy state. When the electrons return to their ground level, the energy difference between the two states is released as light.

They are known as quantum dots for two reasons. First, they exhibit quantum properties thanks to how they confine electrons within themselves. Quantum effects are those subatomic laws of physics that scientists are still trying to fully understand, but that we can already apply in devices like quantum computers.

They are known as points because they are so small that they are virtually zero dimensional. In other words, they are a single point with no width, length, or height. Well, okay, they’re a few dozen atoms wide, but they’re so close to being zero-dimensional points that the wacky laws of quantum mechanics come into play.

What makes quantum dots so useful?

Plastic tubes with quantum dots of perovskite nanocrystals, luminescent with all the colors of the rainbow under ultraviolet radiation.
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Quantum dots behave like excited atoms, but they differ in one fundamental respect. The light you get from an atom or quantum dot is equal to the amount of energy absorbed and released, which determines the wavelength and therefore the color of the light. However, one type of atom (eg, iron, sodium) will always emit the same color wavelength.

Quantum dots, on the other hand, may be made of the same semiconductor material, but produce different wavelengths depending on their size. The larger the dot, the longer the wavelength and vice versa. So the larger dots tend toward the red end of the spectrum and the smaller dots toward the blue end.

This attribute of quantum dots means you can precisely control the emission of colored light for bright, accurate colors.

how to make quantum dots

Quantum dots have a precise structure because they are crystals. The silicon wafers our microchips are made from also grow as crystals, which self-organize into atomic patterns. This is why we can make quantum dots with precise structures at the nanometer scale. If we had to build them one atom at a time, they wouldn’t be very practical!

They can be made by shooting beams of atoms at a substrate to build crystals, you can shoot ions (free electrons) at your semiconductor substrate, or by using X-rays. Quantum dots can also be created by chemical and even biological processes. However, bio-manufacturing research is still in its early stages.

Where are quantum dots used?

Apart from QD-OLED and QLED screens, most people are aware of quantum dots, there are numerous applications for these invisible specks in many different technologies.

Solar panels are an important potential application of quantum dots. Today’s silicon-based solar cells are already quite efficient at harvesting energy from light, but because quantum dots can be “tuned” to absorb light from various parts of the electromagnetic spectrum, they could produce solar panels. much more efficient. These panels would not only be more efficient, but would also be cheaper to produce, since the process to create the necessary quantum dots is relatively simple.

In theory, a solar cell could be made from pure quantum dots, but they can also be used in hybrid solar cells. Boosting the efficiency of other solar energy technologies.

Quantum dots can be used in photon detectors, have exciting potential in biomedicine, and could even lead to much cheaper and more efficient light-emitting diodes.

An exciting application of quantum dots is in cancer treatment, where the dots are designed to accumulate in specific organs to release anticancer drugs as well as advanced imaging. They may even play a role in the early diagnosis of tumors.

Quantum dots may also hold the key to photonic computing, as electrical circuits become so small that quantum effects make it impossible for electrons to flow through them. photon computing may be the next step. Quantum dots could solve several of the problems still facing photonic computing.

RELATED: What is a QD-OLED screen?

Quantum defies the imagination

Richard Feynman, the famous American physicist, is often quoted as saying something like, “If you think you understand quantum mechanics, you don’t understand quantum mechanics.” Albert Einstein is also known for drawing the line by venturing over it, so we’re pretty comfortable admitting that we don’t. Really understand quantum dots.

What we do understand is how versatile they are and the amazing technological innovations that they will allow in addition to making computer screens more pleasing. So the next time you marvel at the intensity of your QLED TV, take a moment to think about the incredible subatomic magic that’s going on so you can get a better picture, and how quantum dots could one day be doing important work. inside your body and out in the world