Quantum dots and a bright future

Quantum dots are semiconducting crystals just a few nanometres wide. They are typically made from combinations of transition metals and/or metalloids, just like regular semiconductors. Cadmium selenide and cadmium telluride are probably the most prominent compounds used in quantum dots.

As they are so small, a quantum dot’s excitons (a type of quasiparticle, where an excited electron combines with the positive hole it leaves behind) experience quantum confinement in all three spatial dimensions. Changing the size of a quantum dot changes its properties, in particular its fluorescence, meaning that they can be tuned to different colours. The smaller the nanoparticle, the narrower its photoluminescence wavelength; smaller dots emit blue light while larger ones emit red light.