Tuning the energy bandgap of CdSe nanocrystals via Mg doping

CdSe nanocrystals with a zinc blende structure allowed apparent Mg doping (∼9.8 at.%). Inverse micelles were formed at a low temperature as templates for the zinc blende CdSe nanocrystals, and paraffin oil and oleic acid were used as a solvent and a surfactant, respectively. The Mg doping was shown by energy dispersive x-ray spectroscopy (EDS) and inductively coupled plasma (ICP) atomic emission analyses. Although the particle size of the CdSe and Mg-doped CdSe nanocrystals were ∼6 and ∼8 nm, respectively, the Mg-doped ones show the obvious blueshift in the UV-visible absorption spectra due to the increase in the bulk energy bandgap, which is decisive evidence for the real Mg doping in the CdSe lattices. The Mg-doped CdSe nanocrystals also showed the blueshift in the photoluminescence (PL) spectra, and their PL intensity was comparable to or even higher than that of the undoped CdSe. This impurity doping using the zinc blende structure is suggested as a simple and effective way to tune the energy bandgap of CdSe nanocrystals and, in turn, to control their light emission colour.