Multi-carrier processes in halogenated Si nanocrystals.

We study theoretically an effect of passivation with Cl and Br on Auger recombination and multiple exciton generation in silicon nanocrystal SiX, with X being the passivating element. The nanocrystal electronic structure and rates of these processes are calculated using time-dependent density functional theory. Comparison with the H-passivated Si nanocrystal shows that the bromine coating, despite having less electronegativity, affects the electronic structure and transition rates more than the chlorine one due to the stronger structural perturbations caused by the greater surface atoms.

Effects of surface halogenation on exciton relaxation in Si crystallites: prospects for photovoltaics.

Ab initio study of Si crystallites (diameter: 1.1-2.4 nm) with fully Cl- or Br-passivated surfaces was performed.