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

► Cu-doped ZnO quantum dots synthesized by laser ablation in PVP aqueous solution. ► The Cu-doped ZnO QDs have ultrafine size, good dispersibility, and high stability. ► We control the doping extent by changing the atomic ratio in Zn/Cu composite targets. ► The Cu-doped ZnO QDs exhibit blue emission with tunable wavelength. ► Laser ablation presents an effective method for obtaining various doped nanocrystals.