Total Energy and Electronic States of CdSe Nanoparticles

The authors fulfilled calculations of the total energy and electronic states of CdnSen nanoparticle:“wurzite”, “sphalerite” and “rock-salt” types of the structure. It was shown that at n ≤ 72 the “rock-salt” type is the most favorable energetically. However the extrapolation of the behavior of the energy per Cd-Se atomic pair shows that for n > 130 (corresponding to a size of about 2 nm), particles with a “wurtzite” structure can be more advantageous. Particles of the “wurtzite” and “rock-salt” types have an electronic structure with an energy gap. For particles with the “wurtzite”structure, the gap width decreases with increasing particle size: from 3.3 eV to 2.2 eV as the particle increases from 0.5 nm to 1.5 nm. For particles of the “rock-salt” type, the gap width grows slightly, remaining about 3 eV.“Sphalerite”-type particles have a metal-like electronic structure.