Hybrid luminescent CdS@ZnS nanocomposites

Abstract

Herein, tailoring and characterization of hybrid luminescent CdS@ZnS nanocomposites are discussed. Hybrid nanocomposites of CdS@ZnS, with different Cd2+/Zn2+ molar ratios, were fabricated by a zinc, cadmium acetates-thiourea complex thermolysis route at 200 °C for 3 h. The structure and the microstructure of the as prepared nanocomposites were characterized by XRD and TEM. XRD analysis confirmed the presence of two different phases with distinct structure; wurtzite and zinc blend of phase abundance directly dependent on the Cd/Zn ratio. XRD as well as TEM micrograph confirm the quantum dot size of the two composite phases; decreasing as the Zn content increases. The chemical signature of each composite phase was assigned by FTIR. UV/vis spectra show that the absorption edges of the CdS@ZnS nanocomposites are located between those of CdS and ZnS phases and the absorbance at the peak maximum was practically dependent on the Cd2+/Zn2+ molar ratio. The PL spectra show fascinating luminescence characteristics such as strong and stable visible-light emissions of different colors. The emission peak positions and PL intensity are tuned with Cd2+/Zn2+ molar ratio. This study indicates that the optical properties are controlled by the heterointerface states between wurtzite and zinc blend. This work recommends the necessity of Rietveld structural analysis for distinguish between different structural phases within the nanocomposite.