Plasmon-Enhanced Fluorescence Of Doped Energy Level Of ZnS:Mn Qu-Antum Dots

Doped semiconductor nano-materials have brand-new optical properties over their counterpart bulk materials.Generally the photoluminescence of the doping level is not strong enough to be applied in practice.Lots of studies show that nano-metal plasmon can enhance the optical field as well as tune the spectrum which makes it available in application.The basic properties of nano-semiconductor materials,the development and the application of doped nano-semiconductor materials as well as surface plasmon resonance(SPR)is demonstrated.Moreover,the plasmon-enhanced fluorescence of doping energy level of Quantum Dots is studied.The main research results are as follows:(1)The computation of electronic structure and optical properties of ZnS:Mn QDs is carried via DFT:Firstly,we make a summary about DFT and the computation plan is formed.Secondly,we compute and analyze the structure of ZnS bulk and ZnS nanoparticle cluster in the electrical,magnetic and optical properties in contrast to undoped nano-materials respectively.The energy band structure,density of electronic states,absorption spectrum and magnetic moment are included in this compu,tation.By comparing the doped material with undoped ones,we fnd that the doping level of ZnS:QDs is incorporated between the conduction band(CB)and the valence band(VB).(2)The synthesis of ZnS:QDs and PL characterization of ZnS:Mn QDs:Firstly,the basic properties of ZnS semiconductor materials is introduced.Secondly,ZnS:Mn QDs are prepared via a solution-based method using PVP(polyvinylpyr-rolidone)as a capping agent.The morphology was characterized using TEM.By changing the concentration of Mn2+ in ZnS QDs,the photoluminescence is enhanced regularly.We observe that the doping Mn2+ of ZnS QDs exhibit 600nm PL emission,this value reaches the maximum when the doping level is 5%.(3)The scattering,the absorption and extinction coefficienct of nano-metal are studied via FDTD,the changing properties of nano-metal structures can be attributed to their shapes,sizes,surroundings,etc.Then,the composite system of nano-metal structure and ZnS:Mn QDs is fabricated,the PL and the mechanism behind the phenomenon are discussed.We fabricate the composite system of nano-metal structure with ZnS:Mn QDs by spin-coating ZnS:Min QDs on the nano-metal structure films.The PL results show that the composite system exhibits stronger PL,which is linked to the doping energy level of Mn2+ in ZnS:Mn QDs.Furthermore,PL enhancement is studied when different annealing temperatures of Au nanoparticle were implemented in the preparation.We observe that the PL of doping level located in ZnS:Mn QDs can be increased by 2.1 fold in contrast to the pure ZnS:Mn QDs under the nano-metal structure which annealed at 120℃ for 30 min.Lastly,the SPR enhancement and the charge transfer theory are discussed thoroughly in order to analyze the PL enhancement mechanism.