| The localized surface plasmon resonances generated in noble metal nanostructures can form strong localized field enhancement in the sub-wavelength range,realizing the enhancement of the interaction between light and matter on the nanoscale.The local surface plasmon resonance can be tuned by adjusting the particle composition,shape,size and surrounding dielectric environment of the nanostructure.Therefore,noble metal nanomaterials are widely used in solar cells,micro-nano optoelectronic devices,data storage and biosensing and other fields.In particular,when the gap between noble metal nanoparticles is very small,its coupling effect will be greatly enhanced,resulting in a rich optical response and signal enhancement.Therefore,it becomes particularly important to construct periodic array structures of nanoparticles with specific sizes and morphologies.Although the top-down physical processing method can be used to prepare nano-periodic arrays with arbitrary morphology,due to the limitation of resolution and other factors,the operation is relatively complex and the cost is high,so it is difficult to fabricate and produce in large areas.By using the bottom-up chemical processing method for the self-assembly of nanoparticles,the dense arrangement structure of large area monolayer or multi-layer nanoparticles can be realized,and the particle gap can be regulated by the molecular weight of the ligands on the surface of the nanoparticles.It can enhance the surface plasmon coupling effect and has a broad application prospect.Therefore,how to simply and efficiently prepare periodic nanoarrays with different morphologies has become the key to expand the application of noble metal nanomaterials.In order to solve the above problems,a method based on polystyrene microsphere template to self-assemble nanoparticles at the gas-liquid interface to prepare adjustable period gold nanoparticle film array structure is proposed in this dissertation.The gold nanospheres with smooth morphology,regular size and mono-dispersity were prepared by seed-mediated growth method,and the monolayer or multilayer thin film array with hexagonal close arrangement structure of gold nanospheres was prepared by gas-liquid interface self-assembly method.This method combines substrate-assisted self-assembly and interface self-assembly.By adjusting the period of the substrate polystyrene colloid mask or the molecular weight of the coated PS-SH,the period of the gold nanoparticle film array and the particle gap of the gold nanospheres can be changed,thereby effectively adjusting the surface plasmon coupling effect of the nanostructure.In addition,this method improves the shortcomings of traditional lithography technology,such as high processing cost and complex operation,and plays a positive role in the fabrication of array structures with controllable plasmon coupling.The specific work of the paper involves the following three aspects:(1)The preparation process of polystyrene(PS)colloidal mask and the effect of various experimental conditions on the quality of PS colloidal mask were studied.Large-area ordered and hexagonal close-packed PS colloidal masks with PS sphere diameters of 800 nm,1.5μm,and 2μm were successfully prepared by controlling the experimental parameters,and can be transferred to any desired substrates.(2)Gold nanospheres with ultra-smooth and perfect spherical morphology,regular size and monodisperse were successfully prepared by seed-mediated growth method.Large area regularly dense gold nanoparticle film array structures were successfully prepared by gas-liquid interface self-assembly nanoparticles,which can be deposited on substrates with different morphologies.The diameter of gold nanospheres can be controlled within the range of20～100nm by adjusting the amount of solution added in the process of gold ball growth and oxidation etching;the interval between gold nanoparticles can be effectively controlled by changing the molecular weight of mercaptan polystyrene;the layer number and thickness of gold nanoparticles can be effectively controlled by adjusting the concentration and amount of gold spheres in chloroform solution during dripping.(3)The self-assembly of nanoparticles based on polystyrene colloidal mask is a strategy to achieve the periodic orderly arrangement of large area nanoparticles.This method combines colloid mask with interface self-assembly,which has the advantages of simple operation and low cost.It provides a possible scheme for the fabrication of periodic arrays of other morphology nanoparticles by self-assembly. |
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