| The self-assembly mechanism of inorganic nanoparticles is still an outstanding question due to the diversity and non-doping of their interactions.On the basis of chiral selective resonance absorption,the double helical nanoribbon was successfully assembled by using circularly polarized light induction technique.In this study,a new photooxidation dipole moment mechanism was introduced to study the effect of nanoparticle size on the assembly morphology.Due to the change of interfacial spacing between cadmium sulfide and cadmium telluride,the intermolecular dipole moment decreased with the increase of nanoparticle size.Firstly,the degree of photooxidation of cdte quantum dots and ligands is different due to the illumination in different polarization directions,which affects the structure and optical properties of the quantum dots.Non-polarized light tends to promote the photooxidation of cdte quantum dots,which leads to the photodegradation of quantum dots and the blue shift of fluorescence photoluminescence(PL)spectrum,the intensity of the light also decreased with it.However,circularly polarized light is more inclined to promote the photooxidation of ligands,so as to form a cadmium sulfide layer on the surface of quantum dots,which reduces the unsaturated bond and dangling bond on the surface of particles,inhibitsthe activity of surface atoms,and reduces the level defect,resulting in the continuous increase of quantum dots and the red shift of photoluminescence spectrum,and the enhancement of luminous intensity.The reason for this result is that the spatial configuration of the bond between quantum dots and organic ligands leads to the different light response of quantum dots and ligands to the two properties and thus different light oxidation processes.Secondly,the operability of atomic morphology could be achieved by adjusting the size and concentration of nanoparticles in the solution.It was found that the competition between photooxidation and self-assembly and between dipole-dipole interaction and electrostatic repulsion could be regulated by the size of nanoparticles,the concentration of dispersions and the proportion of mercaptan ligands in solution.Appropriate nanoparticle size,lower dispersion concentration and lower ligand ratio are the key to prepare chiral bonds.Finally,a new mechanism for enhancing the dipole moment of nanoparticles is proposed by studying the self-assembly morphology,stoichiometric ratio,microstructure and optical properties of nanoparticles with different particle sizes.Light from different polarization directions leads to different degree of photooxidation of cadmium telluride quantum dots and ligands,which affects the morphology,structure and optical properties of quantum dots.The nanostructure system recombination induced by circularly polarized light can provide a new and powerful technique for chiral materials and open up a new field for chiral nano-semiconductor materials. |
