Preparations And Characterizations Of SiO₂ Nanospheres Incorporating Multiple CdSe/ZnCdS Quantum Dots

Cadmium selenide quantum dots?QDs?is one of the earliest researched II-VI semiconductor nanocrystals and has been widely used in biomedical and optoelectronic field due to its mature process and preparation,high luminous efficiency,good optical performance.To be applied in biomedical areas,the problems of hydrophilic and toxicity of Cd Se QDs must be solved.This study started with the preparation of CdSe/ZnCdS QDs with uniform particle size distribution,and then to incorporate multiple CdSe/ZnCdS QDs into SiO₂ nanosphere through facile sol-gel and microemulsion methods on regarding to the interaction between QDs and silane coupling agents.The detailed works of the present study were shown as follows:?1?Synthesis of highly luminescent CdSe/ZnCdS QDs through an organic routeConditions such as reaction solvent,the precursor injection rate and molar concentration of CdSe core impacted on the properties of the prepared QDs have been investigated.The final prepared CdSe/Zn CdS QDs show homogeneous size distribution with full-width at half-maximum less than 32 nm,good stability and luminescent efficiency as high as 60%.?2?Simple method to prepare Si O₂ nanospheres containing multiple CdSe/ZnCd S QDsThrough a modified one step "St???ber" method,multiple CdSe/ZnCdS QDs were incoporated into silica nanospheres.These nanoparticles showed monodisperse and uniform distributions,while their luminescent efficiency remained 60% of the initial value of the QDs.The method was operated in very simply way,and has a high material utilization yield.?3?Preparation of SiO₂ nanospheres containing multiple CdSe/ZnCdS QDs by a microemulsion methodThrough the interaction between QDs and OTES as the silane coupling agent,QDs were dispersed into the micelles formed in aqueous solution.After adding the Na2SiO3,nanospheres were then prepared.This method avoids the surface damages of QDs caused by ligand exchanges between water-oil phases.SiO₂ nanoparticles incorporating multiple CdSe/ZnCdS QDs with luminous efficiency up to 32% were prepared through optimizing the experimental conditions.