First-principles calculations of electronic coupling effects in silicon nanocrystals: Influence on near band-edge states and on carrier multiplication processes

• We study effects induced by nanocrystals interplay on near band-edge state properties.
• We prove that energy and charge carrier multiplication effects can lead to a red-shift of the photoluminescence peak.
• We test the validity of the dipole–dipole Foster approximation.

Arrays of closely packed nanocrystals show interesting properties that can be exploited to induce new features in nanostructured optoelectronic devices. In this work we study, by first principles calculations, effects induced on near band-edge states and on carrier multiplication by nanocrystals interplay. By considering both hydrogenated and oxygenated structures, we prove that interaction between silicon nanocrystals can alter both the energy gap of the system and dynamics of excited states with a relevance that depends on the nanocrystal–nanocrystal separation, on nanocrystals orientation and on nanocrystals surface properties.