Synthesis and optical properties of colloidal core-shell semiconductor nanocrystals quantum dots for sensory application

We present results on the synthesis of core-shell CdSe/ZnS semiconductor nanocrystal quantum dots (NQDs) and their optical enhancement properties. A very strong and narrow photoluminescence is observed for sizes varying from 2 to 5 nm. Using an effective mass theory, we model the energy shift for the first excited state for core and core/shell NQDs. Core/shell heterostructure can be used to significantly increase the absorption cross section and decrease the efficiency of Auger recombination. Opal structures prepared from silica beads are also reported. This photonic crystal infiltrated with NQDs shows promise in biological detection.