A semiconductor nanocrystal whose emission wavelength is set by its physical size rather than its composition.
A 2 nm cadmium selenide dot fluoresces blue; a 6 nm dot of identical composition fluoresces red. Because the emission band is narrow and placeable, quantum dots give a display a wider colour gamut than the phosphors they replaced — the commercial application that took the technology from a 1980s physics result to a shipping television.
Articles that define quantum dot in context.
The human-hair comparison tells you nothing useful. Six anchors at the right order of magnitude, and the two mechanisms that make small materials behave differently.
Why a quantum dot's colour is set by its size, and why the journey from a 1981 observation to a shipping display took three decades of manufacturing rather than physics.
Nanotechnology is defined by scale rather than substance. Here is what changes between 1 and 100 nanometres, why it changes, and why a nanoparticle of a familiar material can be a genuinely new one.
