Control of Cu-doping and optical properties of ZnO quantum dots by laser ablation of composite targets

Cu doping of ZnO quantum dots (QDs) was carried out by laser ablation of Zn/Cu composite targets immersed in PVP aqueous solution. Zn/Cu core–shell particles were firstly prepared by a galvanic replacement reaction, and then they were pressed into targets with different Zn/Cu ratios for laser ablation. Under the extremely non-equilibrium conditions generated by the pulse laser used, a large amount of Cu-doped ZnO QDs were produced with ultrafine size, good dispersibility, and high stability. On the other hand, the dopant concentration was feasibly controlled from 1.8% to 4.8% by changing the atomic content of Cu in Zn/Cu composite targets. Cu-doped QDs exhibited blue emission with tunable wavelength, which was ascribed to electronic transitions from the conductor band of ZnO to the acceptor levels related to Cu dopants. As a facile and versatile technique, laser ablation is believed to be an effective way for fabricating various doped nanocrystals.