Controlling Energy Transfer in Silicon Quantum Dot Assemblies Made from All-Inorganic Colloidal Silicon Quantum Dots

The optical response of an assembly of semiconductor quantum dots (QDs) is strongly modified from those of isolated ones by the inter-QD coupling. The strength of the coupling depends on the size, the inter-QD distance and the number of interacting QDs. In this work, we control these parameters of silicon (Si) QD assemblies by layer-by-layer growth of all-inorganic colloidal Si QDs. We perform detailed photoluminescence (PL) and PL decay dynamics studies for the assemblies made from monolayers of Si QDs 3.0 and 6.8 nm in diameters by precisely controlling the interlayer distance and the number of layers. From the analysis of the data with the Förster resonance energy transfer (FRET) model, we quantitatively discuss the relation between the FRET efficiency and the Förster radius in Si QD assemblies

Energy Transfer in Silicon Nanocrystal Solids Made from All-Inorganic Colloidal Silicon Nanocrystals

Energy transfer between silicon (Si) nanocrystals (NCs) in Si-NC solids was demonstrated by photoluminescence (PL) spectroscopy. Clear differences of PL spectra and the decay rates between solutions and solids of Si-NCs were observed. The change in the PL properties caused by the formation of solids could be explained by the energy transfer from small to large NCs in the size distribution. In order to obtain further evidence of NC-to-NC energy transfer, the size distribution was intentionally modified by mixing solutions of NCs with different size distributions. NC solids made from the mixed solutions exhibited significantly different PL spectral shape and decay rates from those made from unmixed solutions, providing clear evidence of NC-to-NC energy transfer in Si-NC solids