MIT team finds that the ratio of component atoms is vital to performance.
This illustration shows a lead sulfide quantum dot array. Each quantum dot (the colored clusters) is 'passivated' by molecules that bind to its surface. Dots that are made up of unequal amounts of lead and sulfur tend to cause electrons (shown in red) to become highly localized, which can substantially lower the electrical transport of the device. Image: Donghun Kim and Jeffrey C. Grossman