An Easy Recipe For Quantum Dots

An anonymous reader writes "Semiconductor nanocrystals, better known as quantum dots, might find their way into solar cells, cancer tests, and all sorts of other products. Making them is surprisingly easy, if you have the right equipment, but it's not cheap. A team of reporters from Chemical and Engineering News visited Johns Hopkins and learned how to make the pricey particles (YouTube video). They have produced a slick video that explains the whole process."

Comments

Why we care about quantum dots

[JoshuaZ]

Quantum dot are semiconductors where their electrons and holes for electrons (which can be for most purposes thought of as particles themselves) are bound in special tight pairs that are unable to move much. One really nice is that their electronic properties can vary with the size and shape of the crystal. In particular, the band gap :, which is the energy range where electrons cannot live, can vary and be carefully controlled in a quantum dot. Insulators have really big band gaps, conductors have none or close to none, and things with medium band gaps are generally semiconductors. So being able to control your bandgap size means you can make semiconductors with essentially any properties you want.

The reason that quantum dots are so exciting for solar cells is that the way they transfer light to electricity can be fundamentally different than the standard process. For normal solar cells there's a theoretical maximum efficiency before which some of the energy has to go to waste heat. There are clever ways you can take advantage of some of this otherwise wasted heat, but by and large this is true waste heat. However, there are suggestions that the theoretical limit for quantum dot enabled solar cells should be larger.

This is not the only nice set of properties that quantum dots have. There's been suggestion that properly designed quantum dots could be used to do solid state quantum computing. If this does occur it will potentially allow quantum computers to be much more scalable and fault tolerant which currently are the primary problems preventing quantum computers from being more than lab curiosities. (Disclaimer: I'm not a physicist or an electrical engineer. Details here might be wrong.)