Quantum dots (QDs) are vanishingly small “nano” particles of material. They are so tiny that it would take roughly 100,000 of them to span your fingernail. Owing to their small size, these materials are especially advantageous due to having remarkably high efficiency and size-tunable photoluminescence (PL, light emission) over a wide-range of colors.
QDs typically have an onion-like structure of layers upon layers where subsequent shells protect the precious light-emitting “core” materials from the outside. Their outer surface is terminated with a sort of “hair” composed of organic molecules.
Tuning the size and composition of the dots is achieved by carefully adjusting manufacturing conditions. As size increases, the absorption onset and PL spectrum shifts to redder wavelengths, while decreasing the diameter shifts the absorption and PL shifts towards the blue. The size tunability of QDs make them an attractive alternative to fluorescent dyes or doped phosphors since many colors can be achieved from the same material.