Synthesis of highly luminescent, bio-compatible ZnO quantum dots doped with Na

Na doped ZnO quantum dots of average size 6 nm were prepared using wet chemical route at room temperature without any capping agents and the formation of nanoparticles is confirmed by transmission electron microscope (TEM) and x-ray diffraction (XRD) analysis. Optical band gap of ZnO: Na is found to be blue shifted with decrease in size due to quantum size effects. Incorporation of Na in ZnO quantum dots is confirmed using inductively coupled plasma atomic emission spectroscopy (ICP-AES). Strong room temperature photoluminescent emissions in the violet region due to native defects of ZnO and yellow region resulting from substitutional incorporation of Na in the Zn site was observed from the ZnO: Na quantum dots. Both emission wavelength and integral intensity of emission in the visible region can be well controlled by adjusting the concentration of the alkaline precursor used as the dopant. Highly luminescent bio-friendly Na doped ZnO quantum dots can be used as fluorescent probes in biomedical applications.