Research On The Control Of Luminophore Properties By Noble Metal Nanoparticles

With the increasing development of science and technology,the rapid development of information,biotechnology and energy industries will inevitably put forward new requirements for material performance.The characteristics of intelligence,high integration and high-density storage of components also require smaller and smaller material sizes.Among them,rare earth luminescent materials and carbon quantum dots with excellent optical properties are widely used in lighting,display,anti-counterfeiting and other fields.However,rare earth luminescent materials and carbon quantum dots still have many problems.Due to the unique 4f-4f electronic configuration of rare earth ions,their luminous efficiency is low;carbon quantum dots cause luminous efficiency and easy agglomeration due to the groups and structures on the surface.This article addresses the problems of low luminous efficiency of rare earth ions and low luminous efficiency of carbon quantum dots and easy aggregation.In Chapter 3,we use the precious metal nano-surface plasmon resonance effect to control the local field outside rare earth ions to control the luminescence of rare earth ions.In Chapter 4,we use MOF materials to encapsulate carbon quantum dots to solve the problem of easy aggregation of carbon quantum,and use precious metal nanoparticles to regulate the luminescence of carbon quantum dots.The main contents are as follows:1.Research on the regulation of the luminescence of NaYF₄:Yb³⁺,Er³⁺by the surface plasmon resonance effect of gold nanometersThis part of the experiment regulates the surface plasmon resonance effect of gold nanoparticles by adjusting the size and surface morphology of gold nanoparticles,thereby adjusting the upconversion luminous efficiency of NaYF₄:Yb³⁺,Er³⁺.It includes the following two contents:the size effect of rod-shaped gold nanoparticles regulates surface plasmon resonance and the regulation of surface morphology of gold nanoparticles regulates surface plasmon resonance.（1）The local field of surface plasmon resonance under the influence of the size effect of gold nanorods,regulating the luminescence of NaYF₄:Yb³⁺,Er³⁺In this section,by adjusting the synthesis reaction conditions and the type and content of additives,rod-shaped gold nanoparticles with different aspect ratios were prepared,and the regular changes of the surface plasmon resonance peak from visible light to near-infrared light were realized.Subsequently,the rod-shaped gold nano-particles and the hexagonal phase NaYF₄:Yb³⁺,Er³⁺nanoparticles were compounded to prepare a composite luminescent film.Under the excitation of a 980nm laser,the up-conversion luminescence enhancement was realized.Through the analysis of up-conversion luminescence spectra under local field regulation of rod-shaped gold nanometers with different aspect ratios,it is found that the up-conversion luminescence intensity of NaYF₄:Yb³⁺,Er³⁺particles is successfully regulated,and the highest in the green light region and the red light region are achieved respectively.Up to 7.1 times and 11.6 times enhancement effect.Further testing the lifetime test and power intensity relationship test of Yb-Er up-conversion luminescence,it is found that the rod-shaped gold nanometers with different aspect ratios will not affect the lifetime of Yb-Er up-conversion luminescence and Yb-Er upconversion luminescence is a two-photon process.We attribute the highest enhancement effect of the rod-shaped gold nano-local field with an aspect ratio of 6.9 to NaYF₄:Yb³⁺,Er³⁺particles,due to the plasma absorption of 999nm near-infrared light by its surface electrons,and NaYF₄:Yb³⁺,Er³⁺nanoparticles The near-infrared up-conversion excitation light matches,resulting in a strong local field,which ultimately enhances the excitation efficiency of Yb-Er up-conversion luminescence in NaYF₄:Yb³⁺,Er³⁺nanoparticles.（2）The local field of surface plasmon resonance under the influence of the morphology effect of gold nanoparticles regulates the luminescence of NaYF₄:Yb³⁺,Er³⁺In this part of the content,by adjusting the synthesis reaction conditions and the type and content of surfactants,four kinds of spherical gold nanometers,cubic gold nanometers,triangular gold nanometers,and star-shaped gold nanometers were prepared respectively,with basically the same size and morphology.Different nanoparticles are then compounded with hexagonal NaYF₄:Yb³⁺,Er³⁺nanoparticles to prepare a composite luminescent film.Under the excitation of a 980nm laser,the up-conversion luminescence is enhanced.Through the up-conversion luminescence spectra analysis of different shapes of gold nanometers under local field regulation,the up-conversion luminescence intensity of NaYF₄:Yb³⁺,Er³⁺particles has been successfully regulated,and achieved up to 16.7 times in the green light region and the red light region,respectively.And 23.3 times the enhancement effect.Through the life test of Yb-Er upconversion luminescence and the power intensity relationship test,it is found that the change of the surface plasmon resonance local field caused by the morphology change will not affect the life of the Yb-Er upconversion luminescence,but it will affect the Yb-Er upconversion.The luminescence process of luminescence indicates that gold nanoparticles controlled by morphology can use the polygonal angle effect to provide a strong local field environment and effectively enhance the upconversion luminescence of NaYF₄:Yb³⁺,Er³⁺nanoparticles.In short,through the adjustment of the gold nano size and morphology in this chapter,the near-infrared upconversion luminescence intensity of AuNPs@NaYF₄:Yb³⁺,Er³⁺composite luminescent film has been adjusted;through the study of the Yb-Er upconversion luminescence process,We found that the mechanism of the local field’s enhancement of Yb-Er upconversion luminescence is mainly the excitation field enhancement.The above results provide a theoretical basis for the design of new upconversion luminescence enhancement composite materials.2.Study on the luminescence properties of the porous structure MOF material encapsulated silver cluster/carbon quantum dot composite materialIn this section,the ZIF-8 metal-organic framework material was successfully prepared,and the porous structure was used to encapsulate the carbon quantum dots using the coating method and the adsorption method respectively.On this basis,silver nanoparticles are reduced in situ in the porous structure of the MOF material.By controlling the amount of the reducing agent,the amount and existence of the silver particles in the hollow structure are controlled,thereby regulating the luminescence of the carbon quantum dots.Through the analysis of the structure by infrared spectroscopy,combined with the changes in the excitation and emission peak positions of the fluorescence spectrum,we believe that the high luminous intensity of the carbon quantum dots encapsulated by the coating method is mainly due to the coating reaction between the carbon quantum dots and the ZIF-8 organic ligand.In the process,the effective passivation of the surface improves the luminous efficiency of the carbon quantum dots.At the same time,the silver nanoclusters in the MOF structure can further enhance the luminescence of the carbon quantum dots.The main reason is the energy transfer of the silver clusters,which enhances the excitation efficiency.In addition,the silver nanoclusters will not affect the fluorescence lifetime of the carbon quantum dots.This provides a theoretical basis for the application of solid carbon quantum dot materials.