Many-particle effects in the photoluminescent response of silicon quantum-dot solids

Monodisperse colloidal suspensions of ligand-coated silicon nanocrystals (SiNCs), synthesized through a nonthermal low-pressure plasma reaction, are prepared through density-gradient ultracentrifugation in mixed organic solvents. The SiNC fractions are then self-assembled into close-packed quantum-dot ``solids'' and clusters, and photoluminescent properties of the resulting ordered ensembles are characterized through optical spectroscopy. We find striking manifestations of particle-particle interactions in the measured optical response, and we model these effects using Monte Carlo simulations of the photobleaching kinetics in dense SiNC packings.