Study And Optimization Of The Surface Plasmon Properties Of Noble Metals And KV₃Sb₅

Surface plasmon,an important component of modern nanophotonic,has significant research value and broad application prospects in fields such as biomedical science,optoelectronic conversion,and photocatalysis.On one hand,to regulate and quantify the factors of properties of plasmons in different materials and structures is key to optimizing their optical properties and improving the performance of optical devices.On the other hand,it is a focus of energy structural transformation to find new plasmonic materials to replace traditional ones and achieve efficient utilization of solar energy in the visible-infrared region.In this paper,we target at the controllable factors of local surface plasmonic properties in nanostructures as well as the study of surface plasmon properties of new materials.The following work has been done:（1）The impact of temperature on the localized surface plasmon properties of different noble metal nanoparticles was analyzed.By constructing noble metal nanoparticles of different sizes and using the discrete dipole approximation method,we studied the effects of temperature on the absorption,scattering spectra,and enhancement of near-fields of the nanoparticles.Our results showed that as temperature increased,the surface charge density of the nanostructure decreased,which may inhibit its optical absorption capacity.At low temperatures,devices based on surface plasmons may achieve better optoelectronic conversion efficiency.When the temperature reached 700 K,high temperatures will have a significant inhibitory effect on copper nanoparticles,making them no longer possess localized surface plasmon properties.（2）The optical properties of yolk shell structure have been systematically studied and analyzed,providing a new idea for controlling the properties of surface plasmons.In our research,we used the discrete dipole approximation method to simulate the absorption spectra and near-field enhancement of the yolk-shell structures under the effects of the shell materials and the sizes of their shells,cavities,cores,and then compared them with those of the core-shell nanostructures.The results showed that as sizes of the cavities increased,the absorption peak of Au@Au yolk shell shifted to the near-infrared region.This phenomenon can be physically explained by the dipole coupling model.In addition,we found that yolk-shell structures with metal shells and those with semiconductor shells exhibited opposite trends with changes in size parameters.This phenomenon is due to different coupling modes combining the intrinsic charge distribution of surface plasmons.（3）We investigated the relationship between size parameters and absorption spectra of yolk-shell structures,and proposed a rapid calculation method called back propagation neural network（BPNN）based on deep neural network.The proposed method was based on the basic theory of the discrete dipole approximation and used the backpropagation neural network to map the relationship between size parameters（core radius,core-shell distance,and shell thickness）and absorption spectra,which greatly simplified the calculation process,saved computation time and ensured accuracy comparable to that of the discrete dipole approximation calculation.By analyzing the computational results,we discussed the specific trends of the influence of size parameters on the absorption spectra of yolk-shell structures.In addition,we designed a reverse prediction network based on BPNN to map the relationship between absorption spectra and size parameters,which provided guidance for practical applications.（4）We researched the plasmon properties of a Kagome metal,KV₃Sb₅.Based on quantum theory,we quantitatively studied the interband and phonon-assisted transitions in KV₃Sb₅.By using the Eliashberg spectral function,we obtained the relaxation time of phonon-assisted electron transitions and quantified the dielectric function of KV₃Sb₅.Then the anisotropy of the dielectric function was analyzed and explained from a structural perspective.In Addition,we computed and analyzed the SPP response of KV₃Sb₅,including SPP dispersion,SPP characteristic length related to practical applications,absorption efficiency and near field enhancement.Lastly,we compared the optical properties of KV₃Sb₅with those of the classic plasmonic material,gold.The results showed that KV₃Sb₅ exhibited good optical absorption efficiency in the infrared region.And the absorption efficiency could be compared to that of gold.Therefore,KV₃Sb₅ is promising to become a new and high-quality infrared optical material.