Studies On Preparation, Optical Properties And Physical Mechanism Of Ⅱ-Ⅳ Core-Shell Semiconductor Quantum Dots

Semiconductor quantum dots are one of the new nano materials, because of its unique properties and wide application prospects have attracted the interest of the scientists. And CdO QDs, CdO/ZnO core/shell QDs are Ⅱ-Ⅵ core-shell structure semiconductor quantum dots which with excellent properties. This paper mainly studies synthesize colloidal CdO QDs, colloidal CdO/ZnO core/shell QDs and colloidal ZnO QDs. Studying the microstructures of CdO/ZnO core/shell QDs and CdO QDs by X-ray diffraction and electron microscopy. Studying the optical properties of the CdO/ZnO core/shell QDs and ZnO QDs by ultraviolet (UV) absorption spectroscopy and fluorescence (PL) spectroscopy. Studying the optical properties of the CdO/ZnO quantum dot films, ZnO quantum dot films and the films by mixing CdO/ZnO and ZnO quantum dots, lays the foundation for its application in optoelectronic devices.Firstly, colloidal CdO/ZnO core/shell QDs are synthesized. The TEM images confirm that our CdO/ZnO core/shell QDs have the steady optical properties. The relation between the microstructure and the optical properties is discussed. The XRD peaks of CdO/ZnO core/shell QDs are coincident with those of CdO cores, which confirms the core/shell structure.Secondly, the optical measurements of CdO, CdO/ZnO and ZnO QDs in room temperature show that the PL quantum yield is enhanced during the shell growth. We also find that reaction temperature and reaction time play the important roles in the generation of QDs size distribution. Analyzing the ZnO nanoparticles, its steep absorption edge indicates that the particle size is a uniform distribution.At last, analyzing the PL spectra of CdO films, CdO/ZnO films, ZnO films, the mixed films of CdO/ZnO and ZnO, we find that in the mixed films, when the Zn content is high, the mixed films’UV spectra is closed to the ZnO films’UV spectra, when the Zn content is low, the mixed films’UV spectra move towards to the CdO/ZnO films’UV spectra, the absorption spectrum is adjustable. This Adjustable band play a important role in photoelectric device field.