Balance is key to making quantum-dot solar cells work
There has been great interest in recent years in using tiny particles called quantum dots to produce low-cost, easily manufactured, stable photovoltaic cells. But, so far, the creation of such cells has been limited by the fact that in practice, quantum dots are not as good at conducting an electric charge as they are in theory.Something in the physical structure of these cells seems to trap their electric-charge carriers (known as electrons and holes), but researchers have been hard-pressed to figure out exactly what. Now, for the most widely used type of quantum dots, made of compounds called metal chalcogenides, researchers from MIT may have found the key: The limiting factor seems to be off-kilter ratios of the two basic components that make up the dots.The new findings — by Jeffrey Grossman, the Carl Richard Soderberg Associate Professor of Power Engineering, materials science and engineering graduate student Donghun Kim, and...