Synthesis And Properties Of CdSe And V₂O₃ Based Chiral Nanomaterials

In the past ten years,the research of chiral semiconductor nanomaterials has attracted extensive attention from the academic and industrial circles,and remarkable progress has been made in material synthesis and device applications.However,the origin and influence mechanism of chirality of chiral semiconductor nanomaterials are not clear,and the controllable regulation of chirality is rarely reported.Based on the structure and ligand of CdSe based nanomaterials,this paper systematically studied the chiral origin,aiming to reveal the influence mechanism of chiral semiconductor nanomaterials.V₂O₃nanomaterial with high activity was synthesized.To realize real-time reversible regulation of V₂O₃ film chirality under voltage drive.The relevant research in this paper provides a new idea for the synthesis,assembly and modification of chiral semiconductor nanomaterials,and a new method for the design,regulation and application of chiral semiconductor devices.The main research contents are as follows:Effect of structure on chiral CdSe based nanomaterials.（1）L/D-Cys-CdSe tetrapod nanostructures were synthesized by chiral ligand exchange method.The chiral mechanism of CdSe Tps is proposed.The zinc blende core and wurtzite arm interact with L/D-Cys by electron coupling and hybrid resonance respectively.The relationship between the size ratio of core to arm and the chiral strength was discussed.When the ratio reached 3.6,L/D-Cys-CdSe Tps get the best chiral strength.（2）The Cu₂S/CdSe core-shell structure was synthesized by successive ion layer adsorption method,and its structure and optical properties were characterized by TEM,XRD,PL and UV-vis.Using L/D-Cys and L/D-Pen to stablize CdSe Tps surface,the thickness of CdSe shell will directly affect the chiral signal and the chiral strength.When the thickness of CdSe shell get 6 layers,it shows the strongest chiral activity.The g-factor of D-Pen-Cu₂S/CdSe 6 layer is 1.65×10^-4 at 590 nm.The experimental results show that the structure of semiconductor nanomaterials plays a decisive role in chiral properties.Effects of ligand on chiral CdSe based nanomaterials.（1）CdSe quantum dots with5 different surface ligands were synthesized by hot injection method.When the same cysteine was used to stablize the CdSe surface,CdSe quantum dots obtained opposite chiral signals.Based on the analysis of FTIR,¹H NMR,³¹P NMR,EA,TGA and ICP-AES,concluded that the binding strength and molecular conformation of the original ligand affect the molecular arrangement of cysteine on the surface of CdSe quantum dots.The original ligand caused a 10-fold difference in the chiral strength,and the highest g factor is up to 6.16×10^-4.The difference g factor was attributed to the difference in cysteine coverage rate on the surface of CdSe quantum dots.（2）Chiral CdSe quantum dots were synthesized in chloroform using 10 kinds of chiral amine ligands.The chiral amine ligands do not affect the luminescence properties of nanomaterials,and CdSe quantum dots showed circular polarization luminescence properties in their fluorescence range.（3）Cysteine derivatives were used as chiral ligands of Cd Te quantum dots to explore the self-assembly growth process and analyze the effects of chiral ligands on the chiral signal and growth direction of Cd Te helices.Cd Te helices show high chiral optical activity in the 300-1300 nm range.The assembly yield is more than 90%,and the monodisperse Cd Te helice have perfect directivity and crystallization.The experimental results indicate that surface ligands play a key role in the chiral activity,circularly polarized luminescence and chiral assembly of semiconductor nanomaterials.Synthesis and property of chiral V₂O₃.The L/D-tartaric acid stablized V₂O₃nanoparticles show the colorful chiral property in the range of 300-1300 nm,and the initial p H of the reaction has a serious impact on the asymmetry of the nanoparticles.The interaction between tartaric acid and V₂O₃ surface was simulated and calculated,which explained the maximum chiral strength of V₂O₃ nanoparticles at p H 11.V₂O₃nanoparticles mixed with carbon nanotubes and silver nanowires with better electrical conductivity were assembled into ITO glass.We get the chiral nanocomposite film with good electrical conductivity and transparency.The voltage drives zinc ions to intercalate into the lattice of V₂O₃ film,resulting in the change of the chiral property of the film.After changing the direction of the current,zinc ions are successfully deintercalated from the lattice,realizing the chiral cycle regulation of the film.This V₂O₃ nanofilms realizes reversible chiral cycle regulation by voltage driven,and provides the possibility for the construction of multifunctional chiral devices.