Manipulating Photoluminescence Properties Of Nanostructured CdTe By Thio-functionalized Ionic Liquid

Ionic liquids （ILs）, as a novel class of green solvent composed of ions completely, have been widelyused in organic synthesis, catalysis, extraction, separation and many other fields for their unique properties,such as low melting points, little vapor pressure, strong dissolution ability and high thermal stability. Moreimportantly, ILs can be designed to form functional compounds for specific applications by combiningdifferent cations and anions, extending further their applications from synthesis and catalysis to functionalmaterials, resources, environment, biological science, information, electrochemistry, nanomaterials. etc. Inrecent years, the preparation of high-quality CdTe nanomaterials has been realized, as the preparationmethod of semiconductor nanomaterials is gradually optimized from high-temperature injection method tohydrothermal method. However, the organic molecular ligands used in experiments are toxic and nothigh-temperature resistant, which does not meet the concept of green synthesis. Thus the application offunctionalized ionic liquids in the synthesis of semiconductor nanomaterials has become a new researchfocus, which make semiconductor nanomaterials are more widely used in the fields of biological analysis,photodetectors, thermoelectric devices, etc.The maincontents of the thesis are as follows:1. By studying systematically the reaction conditions, the optimal conditions have been drawn for thesynthesis of nanostructured CdTe. The ratio of glycerol and water for the mixture solvent is20%in volume,and thylene glycol and water30%. The concentration of NaOH in the mixture solvent is0.5mol·L^-1,Cd2+-HTe-ratio1:0.8，reaction temperature140℃, reaction time12h, and incubation time96h.2. Changing the concentrations of ionic liquids in reaction medium, we synthesized nanostructruedCdTe with good photoluminescence property and continuous tunability over their size. The emissionwavelength of fluorescence covers440⁶30nm and the color can vary from blue to red under UVirradiation. Additionally, not only the–SH shows passivation effect toward CdTe surfaces, the alkyl chainwith different length can also affect the size and the optical property of CdTe. The longer the alkyl is, thebetter the fluorescence performance is.3. A possible reaction mechanism, in this work, has been proposed from the measurements of XRD,TEM, IR, UV-vis, PL, and reaction phenomena. Cd²⁺ion can form a complex with glycerol and thylene glycol in the strong basic conditions, then change into Cd（SR）2in the presence of thio-functionalized ionicliquids, and further form CdTe precursor by the reaction with HTe-.After precursor was incubated for96h,finally, CdTe nanomaterial can be prepared in certain temperature by solvothermal method. From theexperiment results, it is shown that the reaction mechanism for the preparation of nanostructured CdTe issimilar in glycerol-water cosolvents and in glycol-water cosolvents.