Silicon nanocrystals as fast and efficient light emitters for optical gain

Light-emission and optical gain in a silicon-based material is an intensely studied scientific topic due to its possible application impact. In this article, we study colloidal dispersion of silicon nanocrystals with methyl-based capping. Excellent optical properties of this material include reasonably high luminescence quantum yield (20%) and fast radiative lifetime (10 ns), comparable to direct-bandgap semiconductors. Moreover, luminescence maximum situated in the yellow spectral region (570 nm) indicates lowered free-carrier absorption. Photoluminescence and FTIR measurements combined with ultrafine filtration show that the nanocrystals are dispersed in the solvent as single particles or small clusters, implying that scattering-related losses are also nearly eliminated.

► Addressing issues connected with optical gain in Si nanocrystals. ► Suitable surface capping dramatically influences sample quality. ► Colloidal dispersion of methyl-capped Si nanocrystals has high optical quality. ► High luminescence quantum yield and fast radiative lifetime reached.