The Spatial Distribution Of Plasmon-exciton Coupling And The Manipulation Of MoS₂ Photoluminescence

From the discovery of graphene to the 2D material family,MoS2 as a naturally occurring transition metal dichalcogenides,has attracted great research interest.Because of its large exciton binding energy and unique electronic structure,MoS2 has become an ideal light-matter interaction research platform.MoS2 is a direct band gap material with the strong characteristics of photoluminescence,so it is widely used in optoelectronic applications.At the same time,with the development of plasmonics,the plasmon nanostructures could realize the confinement and regulation of light at nanometer scale,which far beyond the diffraction limit of light and provides an effective research method and theoretical basis in light-matter interaction.Based on these two points,the precise construction of plasmon models and interacting with transition metal sulfides can clarify the mechanism of plasmon-exciton interaction and perform precise control.However,there remain some difficulties in constructing precise nanoscale plasmon structures.Therefore,it is necessary to further explore the plasmon-exciton interaction between the plasmonic structure and the spatial distribution,and these will ultimately be applied to its photoluminescence of system.In this paper,we explore the spatial distribution of plasmon-exciton interactions and studies the influence of coupling strength based on the plasmon gap structure and study the photoluminescence spectrum of MoS2 based on the substrate doping effects.The experiment content is divided into the following parts:(1)Ag nanocube/MoS2/PE layer/Au film was used to build a gap-mode plasmonic structure.Through the characteristics of the layer-by-layer assembly of PE layers,the vertical spatial distribution of MoS2 is realized and the plasmon-exciton coupling strength at different positions in nanoscale is obtained,which directly affects the photoluminescence characteristics of the system.Finally,combined with theoretical calculations,the spatial resolution of the gap-mode plasmonic structure at nanoscale is well realized.(2)The advantages and disadvantages of three preparation methods of MoS2 such as mechanical exfoliation,CVD growth,PVA-assisted method and three transfer method of MoS2 such as dry transfer,stamp transfer and wet transfer were studied.We can choose the appropriate method in different experiments.Besides,by using Au,Alumina and SAM self-assembled monolayers with the substrate effect,we produce the p-type or n-type doping in MoS2 and adjust the photoluminescence characteristics of MoS2.In the next step,we plan to use the doping effect into gap-mode plasmonic structure for more detailed exploration.Finally,we have made a preliminary study on PL of bilayer MoS2,and studied the effect of twist angle on PL spectrum of three exciton peaks.