What is Quantum Dot Technology?
Quantum dots are making waves in the world of TVs and monitors, but what exactly are they? Is this just another misuse of the word "quantum" by marketers, or are these points as incredible as they are supposed to be?
In this section:
The artificial atom
Quantum dots are particles of semiconductor material a few nanometers in diameter. Also called “artificial atoms” (although they are much larger than an atom), these points act similarly to atoms when it comes to their relationship with electrons. They are so small that their electrons are "trapped" and behave like atoms. When UV light hits a quantum dot, its electrons are elevated to a higher energy state. When the electrons fall back to their base level, the energy difference between the two states is released as light.
They are called quantum dots for two reasons. First, they exhibit quantum properties through the way they confine electrons within themselves. Quantum effects are those subatomic laws of physics that scientists are still trying to fully understand, but we can already apply them in devices like quantum computers.
They are called points because they are so small that they are practically zero-dimensional. In other words, it is a single point with no width, length, or height. Well OK, they're a few dozen atoms in diameter, but they're so close to being zero-dimensional points that the wacky laws of quantum mechanics kick in.
What makes quantum dots so useful?
Quantum dots behave like atoms that have been excited, but they differ in one fundamental way. The light you get from an atom or quantum dot is equal to the amount of energy that has been 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, can all be made from the same semiconductor material, but produce different wavelengths depending on their size. The larger the dot, the longer the wavelength and vice versa. Thus, larger dots tend towards the red end of the spectrum and smaller ones towards the blue end.
This attribute of quantum dots means you can precisely control the emission of colored light to achieve vivid and accurate colors.
How to make quantum dots
Quantum dots have a precise structure because they are crystals. The silicon wafers from which our microchips are made are also grown as crystals, which self-organize into atomic patterns. This is why we can create quantum dots with precise structures at the nanoscale. If we were 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 using using chemical processes, and even using biological processes. However, research on biological manufacturing is still in its infancy.
Where are quantum dots used?
Besides QD-OLED and QLED displays which most people are familiar with as quantum dots, there are many applications for these invisible dots in many different technologies.
Solar panels are a major 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 much more efficient solar panels. Not only would these panels be more efficient, but they would also be cheaper to produce since the process of making the necessary quantum dots is relatively simple.
Theoretically, you could make a pure quantum dot solar cell, but they can also be used in hybrid solar cells. Increase the efficiency of other solar energy technologies.
Quantum dots can be used in photon detectors, have exciting potential in biomedicine, and could even create much cheaper and more efficient light-emitting diodes.
An exciting application of quantum dots is in cancer treatment, where the dots are engineered to accumulate in specifically targeted organs to release cancer-fighting drugs as well as advanced images. They may even play a role in the early diagnosis of tumours.
Quantum dots may also hold the key to photonic computing, because electrical circuits become so small that quantum effects make it impossible for electrons to flow through them. computing with photons may be the next step. Quantum dots could solve many of the problems photonic computing still faces.
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 to draw the line by venturing there, so we feel pretty comfortable admitting we don't. really understand quantum dots.
What we understand is how versatile they are and what amazing technological innovations beyond making computer screens look nicer they will enable. So the next time you marvel at the vividness of your QLED TV, take a moment to think about the amazing subatomic magic that happens so you can get a better picture and how, one day, quantum dots might perform important tasks within your body and in the world.
