The Study On Aqueous Synthesis And Properties Of Doped ZnS Quantum Dots

Compared with common quantum dots,the doped ZnS quantum dots have outstanding properties in luminescence,electricity and other fields and have become research focus in material science.In the luminescence properties,the doped ZnS quantum dots have intrinsic quantum dots' excellent luminescence properties.What's more it can effectively control and intensify the properties.Such as the excited lifetime become longer,luminescence properties become s Tab,spectral range become wider.The most importance is that becaused of stokes shift the ZnS quantum dots can avoid quenching phenomenon which is caused by self-absorption.So the doped ZnS quantum dots have more and more important application value in electroluminescence,fluorescence labeling and other fields.In this research we separately mixed the Na⁺?Mg²⁺?Cr³⁺ with ZnS quantum dots with water phase synthesis method.By adding different modifier to determine which modifier can promote the quantum dots properties.By orthogonal experiment of temperature and time to determine the best reaction condition.By changing the doped ion concentration,p H of solution,the ratio of Zn\S and modifier concentration to analyze the luminescence properties of ZnS quantum dots.The results show that the best response time is 5 h,the best response temperature is 80 °C and the best modifier is thiourea.The XRD and TEM show that three kinds of single doped quantum dots didn't change the structure of ZnS quantum dots,the quantum dots approximate sphere and have obvious lattice structure.Synthesizing the results of three kinds of single doped quantum dots,we can know that Cr³⁺ have the best effect on quantum dots luminescence properties.The infrared spectroscopy shows that in the quantum dots synthetic process,ZnS reacted with thiourea.In this research we also combined two of the three ions to prepare three kinds of double doped quantum dots.According the XRD,TEM,fluorescence spectrum and infrared spectroscopy to analyze quantum dots.The results show that double-doping didn't have effect on the quantum dots structure.The quantum dots approximate sphere with reunion phenomenon and have obvious lattice structure.Before and after the single-doping turns into double-doping,the location of quantum dots emission peak appeared to displacement phenomenon.Because of energy transfer in the ZnS: Na⁺/Mg²⁺ and ZnS: Mg²⁺/Cr³⁺ quantum dots,the luminescence properties have changed.However,because of internal size change,the luminescence property of ZnS: Na⁺/Cr³⁺ quantum dots have changed.In the formation mechanism,double-doping ions compared with single-doping ions have greater influence on modifier.