What are nanocrystals?
Omar Manasreh, professor of electrical engineering, College of Engineering, and director of the Optoelectronics Laboratory, replies:
Nanocrystal is a term given to a cluster of atoms the size of a fraction of a micrometer in diameter – less than 100 nanometers. The remarkable thing about these clusters is that they possess a perfect crystalline structure with a very low defect density as compared to their solid counterparts. On the other hand, the properties of nanocrystals are very close to the atomic properties, and in many cases these nanocrystals are called atomic designers. Nanocrystal usually refers to those clusters made of semiconductor atoms, such as silicon and gallium arsenide, while the term nanoparticle refers to clusters of metallic atoms, such as gold and silver. The size of the nanoparticles is usually larger than that of nanocrystals. Nanocrystals have attracted a huge technological interest since many of their optical, electrical and thermodynamic properties show strong size dependence and can therefore be controlled through careful manufacturing processes. The most well-known devices fabricated from nanocrystals are photovoltaic devices, or solar cells. These nanocrystal-based devices are expected to be inexpensive and could be used for mass production.