When energy is applied to an atom, electrons are energised and move to a higher level. When the electron returns to it’s lower and stable state, this additional energy is emitted as light corresponding to a particular frequency. Quantum dots work in much the same way but a quantum dot crystal acts as one very large atom. The energy source used to stimulate a quantum dot is commonly ultraviolet light. The frequency or colour of light given off is not related to the material used in the quantum dot, but by the size of the quantum dot.
Quantum Dot Size and Colour Relationship
Large quantum dots produce light with a long wavelength and small quantum dots produce light with small wavelengths. In terms of colour in the visible spectrum, this means large quantum dots produce red light and small quantum dots produce blue light – sizes in between account for all the other colours in the spectrum. By combining a range of sizes of quantum dots in the same sample, the entire light spectrum can be produced simultaneously and appears as white light.
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