The present disclosure provides a quantum dot having a core-shell structure. To have superior quantum efficiency and optical stability, the quantum dot is of a five element system of Zn—Cu—In—P—S. The quantum dot includes a core formed of In(Zn)P material and doped with copper. The quantum dot further comprises a first shell formed of Cu—Zn—In—S material and surrounding the core and a second shell formed ZnS material and surrounding the first shell.