Organometallic Synthesis And Luminescent Properties Of CdZnSe Alloyed QDs,ZnSe/ZnO Nanocrystals

As an important nanomaterials, semiconductor quantum dots (QDs) exhibiting lots of terrific effects (quantum size effect, surface and interface effect, macroscopic quantum tunnel effect etc.), excellent luminescent properties (narrow emission spectrum and symmetrical distribution, broad absorption spectrum, photochemical stability etc.) and they have been widely used in optical electronic components, biomarkers, solar cells, photocatalysis, and many other fields. At present, organometallic synthesis has obvious advantages in the preparation of QDs, its efficient of synthesis has attracted much attention. However, the current research status of organometallic synthesis show that the choice of organic solvents and ligands are still TOP, TOPO which are poisonous and high consumption. In the exploration of green synthesis, people tried to find the substitution of TOP and TOP. However, the complex preparation process and the influence of impurities which come from the substitution caused the uncontrollable morphology and size of semiconductor QDs, the low quantum yield and the poor luminescent properties.In this thesis, the green environmental and efficient synthesis of preparation were explored. Combining with the recent development of QDs:the affected luminescent properties caused by alloying and the morphology combination control, we used organometallic synthesis, chosen the particular combination of organic solvents and ligands (octadecene and oleylamine), obtained the controllable morphology and size of alloyed QDs and nanocrystals which had excellent luminescent properties through a series of parameter adjustment to control the nucleation and growth of QDs at the appropriate growth temperature and time. The detailed contents are as followed:(1) Used the organometallic synthesis method, used Se-oleyamine as anionic precursors, octadecene (ODE) as organic solvent, synthesized alloyed CdZnSe QDs with excellent luminescent properties. Discussed the changes of morphology, size and distribution of alloyed QDs which come from the content of stearic acid in the reaction system.Explored the defect luminescence of CdSe QDs which caused by oleyamine.(2) According to the research of OA (oriented attachment) mechanism, we obtained the branched nanocrystals ZnSe/ZnO which had two different crystalline structures by organometallic synthesis in octadecene and oleylamine. Discussed the different reaction conditions (mole ratio of reactants, the growth time) impacting on the morphology and ingredient of branched nanocrystals. Moreover, explained the OA process of ZnSe, ZnO efficiently after a series of analysis to different HRTEM of nanocrystals. It provides a new angle to explore the composite structure of nanocrystals under an ex situ observation.(3) Used oleyamine as anionic precursors simply, octadecene as organic solvent, organometallic synthesized ZnO nanocrystals with particular morphology. Analysed the role of oleyamine in the formation of ZnO nanocrystals. Observed the effect to the morphology and the light absorption of ZnO nanocrystals under the different reaction time and temperature.