A quantum dot is a nanocrystal made out of a semicondutor material which is small enough to take advantage of the laws of quantum mechanics. Quantum dots are at the center of a very new and rapidly evolving field of research, with the promise for applications in highly efficient solar cells, transistors and lasers, among other things.

In the case of solar cells, quantum dots are used as the absorbing photovoltaic material. The dots have the advantage of having a band gap that can be tuned simply by changing the size of the nanoparticles, and so they can be easily made to absorb different parts of the solar spectrum.