Modification Of Conducting Polymer On The Surface Of CdTe Quantum Dots And Their Interaction Mechanism

Quantum Dots?QDs?are crystalline materials between bulk materials and molecules.With the rapid development of nanotechnology in recent years,QDs have gradually entered people's life.How to obtain more stable,efficient and environmentally friendly quantum dot materials has become a research hotspot.The quantum dots synthesized via the water phase are not only environmentally friendly,simple in operation,and low cost,but also successfully overcome the difficulties of poor water solubility and biological incompatibility.However,quantum efficiency of QDs synthesized in water is still lower compared with ones obtained via the oil phase.Therefore,people try to modify the surface of QDs in order to improve their photoluminescence properties.Materials used to modify the surface of QDs include SiO₂,organic molecules,and macromelcecules.The combination of QDs and conductive polymers is expected to have the advantages of both quantum dots and polymers.Based on this,this thesis selects conductive polymer to modify CdTe QDs,the main content mainly includes:?1?Modification of Polyaniline?PANI?on the Surface of CdTe Quantum Dots.The aniline monomer was protonated,and polymerized on the surface of CdTe QDs with mercaptopropionic acid as a ligand via initiation by ammonium persulfate?APS?to form a composite material of PANI and CdTe QDs.The experimental results showed that the quantum efficiency of CdTe QDs was improved,and the quantum efficiency of CdTe QDs with yellow-light emission was even increased by about 128%.Through systematical study of the structure and photophysical properties of PANI and CdTe QDs composites,it is concluded that efficient fluorescence resonance transfer from PANI to CdTe QDs occurred.Therefore,the quantum efficiency was improved.The large Stokes shift of the resulted composites indicated the improvement of the anti-interference ability for CdTe QDs,which was advantageous for the application in fluorescent probes.Finally,the application of the composite in fluorescent anti-counterfeiting and fluorescent probes was realized.?2?Modification of Oligopolythiophene?OPTH?on the Surface of CdTe Quantum Dots.Under the action of the surfactant CTAB,initiated with oxidant FeCl₃,the thiophene monomer was polymerized on the surface of CdTe QDs with thioglycolic acid?TGA?as a ligand to obtain the composite of OPTH and CdTe QDs.The obtained OPTH-TGA-CdTe QDs showed relatively more stable in comparison with the pure CdTe QDs and exhibited dendritic nanofibers.Under certain experimental conditions,the quantum efficiency was improved,even the quantum efficiency of CdTe QDs emitting orange light was improved by about 134%.The introduction of OPTH greatly shortened the growth time of CdTe QDs.Finally,the composite mechanism of QDs was studied by systematic study on the photophysical properties and structure of QDs before and after compounding.It is speculated that the mercapto group in TGA and OPTH are edge-oriented by interchain?-?stacking to form OPTH-SH nanofibers,which were transformed into band structure on the surface of TGA-CdTe QDs to form a dendritic skeleton.On the other hand,OPTH partially replaced TGA organic small molecules on the surface of TGA-CdTe QDs,which effectively increased the monomer activity,thus increasing the rapid growth of CdTe QDs.