Space-separated quantum cutting in differently prepared solid-state dispersions of Si nanocrystals and Er3+ ions in SiO2

We investigate the efficiency of Si nanocrystal-mediated photoluminescence of Er3+ ions in SiO2 as a function of quantum energy of incoming photons. We demonstrate that for identical nanocrystals the threshold energy of the recently reported space-separated quantum cutting effect does not change with the nanocrystal-to-Er distance. In contrast, the enhancement of excitation efficiency observed above the threshold, in the high-energy photon regime, diminishes at larger separations, thus exhibiting a clear nanocrystal-to-Er distance dependence.