Silver nanocrystal superlattices: Self-assembly and optical emission

Unique passivated silver nanocrystal superlattices were fabricated via a conventional hydrothermal method. The method is based on a general phase transfer and separation mechanism occurring at the interfaces of the liquid, solid, and solution phases present during the synthesis. A photoluminescence (PL) band centered at 390nm was recorded from the obtained superlattice samples. Spectral analyses suggest that the PL arises from the radiative recombination of sp-band electrons with d-band holes in the silver nanocrystals and its intensity enhancement is due to the surface plasmon and an electrostatic enhancement mechanism analogous to that in surface enhanced Raman scattering.