Investigation Of Preparation And Luminescent Properties Of Chalcogenide Semiconductor Nanocrystals

Chalcogenide semiconductors nanocrystals such as PbS，PbSe，ZnS and CdS haveattracted much attention due to their unique optics, electronics，magnetics properties and theirwide applications, such as communications, military, photoelectric device, biomedicine，etc.As far as optical properties are concerned, chalcogenide semiconductor nanomaterials weredifficult to be used in a variety of optoelectronic devices because of their low fluorescenceintensity, unstability and difficulty in elimination of defect states. Therefore, there is an urgentneed for exploration and selection of proper nanocrystalline synthetic routes to solve theseproblems. In this paper, we synthesized PbSe，PbS，MnS/ZnS quantum dot materials by theaqueous synthesis, ultrasonic assistance aqueous synthesis and LSS method，the growthprocess and luminescence properties of nanocrystals in different synthesis methods areconcerned and discussed. Further more, core-shell quantum dot materials of MnS/ZnS wasproposed to be used in electroluminescent devices. Our research included the following threeaspects:1）Different size of PbS nanocrystals were prepared by LSS method with differentprecursor molar of S/Pb. The relationship between particle size and infrared luminescenceemission was focused and discussed. We also explored the mechanism of nanocrystals growthwith reaction time by particle size changes. The visible region fluorescence emission fromPbS nanocrystals was confirmed by absorption spectrum and PL results on core-shell PbSnanoparticles.2）The quantum dot based light-emission device was fabricated with MnS/ZnS quantumdots as active layer which was prepared by LSS method. The PL spectra results confirmed thediffusion and incorporation of Mn~2+into the ZnS lattice. Then we discussed the light emissionmechanism by the results of photoluminescence and electroluminescence spectrum.3）The size of5.7nm PbSe quantum dots were prepared by the aqueous synthesis method.A weak infared fluorescence emission was observed and the origin of it was analyzed. ThePbS and PbSe nanocrystalline were synthesized in aqueous solution of sodium sulfide andsodium selenite with assistance of burst of energy by ultrasonic method. With PL andabsorption spectra，the fluorescence related to band-gap transition were observed. Theinfluence of sodium sulfide concentration on PbS particle size was discussed.