Preparation And Optical Activity Regulation Of CdSe/CdS Chiral Nanorods Films

As we all know,chiral nanomaterials have been widely used and developed in the fields of optoelectronic devices,biomedicine and so on.Therefore,the preparation of chiral nanomaterials is one of the urgent problems to be solved.In this paper,CdSe/CdS nanorods were used as assembly elements for film formation.The chiral properties of CdSe/CdS nanorods film were studied by amino acid modification,electric field treatment and LB（Langmuir–Blodgett）machine treatment,and successfully prepare chiral film materials with strong chiral properties and easy to control.Finally,the circularly polarized fluorescence properties of CdSe/CdS nanorods were analyzed.The main research contents of this paper are as follows.Firstly,20 nm-200 nm CdSe/CdS nanorods were synthesized using CdSe nanoparticles as seeds by solvothermal method.The length of CdSe/CdS nanorods was controlled by regulating the size of CdSe nanoparticles,synthesis temperature and synthesis time.The CdSe/CdS nanorods synthesized by this method have high yield,wide distribution range of aspect ratio,uniform and no agglomeration,which establishes a good foundation for regulating the optical activity of CdSe/CdS nanorods film.Secondly,in order to self-assemble chiral CdSe/CdS nanorods into macroscopic chiral film materials,three methods were tried:amino acid modification film in this paper;electric field film formation;LB machine method.The results show that the three methods have some effects,however,the LB machine method to get a superior CdSe/CdS nanorods.In this method,CdSe/CdS nanorods are squeezed by the sliding barrier on the air-ethylene glycol interface,which is easy to form a"side-by-side"arrangement and thus have the same orientation.By optimizing the length of CdSe/CdS nanorods,the layer numbers of film and the inter angle of film,a strong chiral nanorods film can be obtained.In addition,the similar chiral signal intensity and the opposite handness of the chiral nanorods film is obtained by clockwise/counterclockwise rotation.At the same time,when the layer numbers of film is 10and the inter angle of film is 45°,CdSe/CdS chiral nanorod film had the ultra-high CD signal of about 1450 mdeg.So far,it has obtained chiral film with the super-strong chiral properties of nanorods self-assembled for the first time by using the LB method,which provides a good strategy and idea for the preparation of chiral nanomaterials by self-assembly.Finally,the circularly polarized fluorescence properties of CdSe/CdS chiral nanorods were investigated.At the same time,the influence of the layer numbers of film and the inter angle of film on the luminescence dissymmetry factor(g_lum)was analyzed,and the circular polarization fluorescent material with high g_lum was obtained.In addition,polarization imaging results show that CdSe/CdS chiral nanorods film have good selectivity to polarized light and can produce periodic changes,providing more possibilities for the development of optoelectronic devices.