Interaction of CdSe/ZnS quantum dots: Among themselves and with matrices

Photoluminescence (PL) of CdSe/ZnS quantum dots (QDs) deposited on Si, fused silica, Au film, shows red-shift; and blue-shift whenever two peaks are present, particularly on silica nanospheres. The red-shift with increasing density of QDs is attributed to interaction between QDs with PL emerging from the lower bonding state, and the second peak is attributed to molecular complexes on the surface of QD interacting with its surrounding matrices. The second peak is too weak to be detected on Si wafer with native oxide. The couplings between QD/QD and QDs/silica spheres via the molecular complexes are explained with a simple model. We also demonstrate that the band-gap of photonic crystals consisting of silica spheres can be stabilized by dehydration, annealing at high temperatures up to 1000 °C.