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.