A minuscule crystal of semiconductor material composed of various compounds of chemicals such as cadmium, zinc, tellurium, selenium and sulfur. Less than 500 nanometers in size, these "nanoparticles" react to electricity or light by emitting their own light across the visible range of wavelengths from 470 to 730 nm.

The applications for quantum dots include solid state lighting, with the potential to render incandescent bulbs obsolete in the future and the ability to paint lighting systems onto materials. They are used in the manufacture of medical sensors and solar cells. Thin film deposits of quantum dots on solar cell substrates substantially increase their voltage output by fluorescing the light before it is captured.