Dilution effects on the photoluminescence of ZnSe quantum-dot dispersions

We report results for the photoluminescence emission intensity from ZnSe quantum-dot dispersions in liquids as a function of particle concentration. The observed emission intensity initially increases with dilution, exhibits a maximum, and then decreases. The optimal particle concentration yielding the maximum emission intensity increases as the particle size decreases. The corresponding optimal interparticle distance was estimated for three quantum-dot populations having different average particle size. The observed behavior depends on fundamental physical interactions between the exciting and emitted radiation and the quantum dots; it is expected to be valid for any quantum-dot dispersion, irrespective of material type.