Quantum dots can be precisely controlled to do all kinds of useful things. School-level physics tells us that if you give an atom energy, you can “excite” it: you can boost an electron inside it to a higher energy level. When the electron returns to a lower level, the atom emits a photon of light with the same energy that the atom originally absorbed. The color (wavelength and frequency) of light an atom emits depends on what the atom is; iron looks green when you excite its atoms by holding them in a hot flame, while sodium looks yellow, and that’s because of the way their energy levels are arranged. The rule is that different atoms give out different colors of light. All this is possible because the energy levels in atoms have set values; in other words, they are quantized.
Quantum dots do the same trick—they also have quantized energy levels—but dots made from the same material (say, silicon) will give out different colors of light depending on how big they are.
Nanoco Group PLC (LON:NANO) leads the world in the research, development and large-scale manufacture of heavy metal-free nanomaterials for use in displays, lighting, vertical farming, solar energy and bio-imaging.
