Dissertation > Excellent graduate degree dissertation topics show

Preparation and Luminescent Properties of Metal Sulfides Nanocrystals Micro Structure

Author: LiBo
Tutor: ZhangXiaoSong
School: Tianjin University of Technology
Course: Condensed Matter Physics
Keywords: Nucleation-doping strategy White light emitting Near Infrared light emitting CdS PbS/CdS core/shell Nanocrystals
CLC:
Type: Master's thesis
Year: 2013
Downloads: 1
Quote: 0
Read: Download Dissertation

Abstract


Semiconductor nanocrystals (NCs) have attracted considerable attention due to the unique optical and electrical properties. They exhibit high fluorescence quantum efficiency, high light stability and superior mobility, which have wide application prospects in lighting, display, solar cells, and detectors, etc. In this paper, CdS and EuxS NCs were synthesized by employing stearate, sulfur, octadecylamine and other "green" chemical composition as precursors. EuxS/ZnS, Er2S3/ZnS, PbS/ZnS, PbS/CdS core/shell NCs were synthesized via hot solution phase chemistry using a nucleation-doping strategy. In addition, the luminescence properties of nanocrystals are concerned and discussed, The detailed contents are as follows:1. CdS NCs with different reaction time were synthesized by thermal decomposition method at two different temperatures. The intensity of the trap emission gradually decreases as the reaction time increases in contrast with that of the band-edge emission, which is explained by LaMer model. The synthesis of CdS NCs at lower temperature produced white light emission under UV excitation mainly due to the smaller particle size; CdS NCs with larger particle size prepared in the higher temperature have a broad emission across500-700nm under the excitation of blue light with460nm, consequently, mixing with the remaining blue light to produce white light. Furthermore, white light-emitting devices used CdS NCs as the intrinsic emitting layer was investigated.2. EuxS NCs were synthesized by thermal decomposition and the luminescence properties of NCs at different times were discussed. All of EuxS NCs emit white light. EuxS/ZnS core/shell NCs were synthesized by a nucleation-doping strategy. Moreover, emission intensity of EuxS/ZnS NCs has been significantly improved compared to that of EuxS NCs. Er2S3/ZnS NCs was synthesized by a nucleation-doping strategy. The emission intensity of Er3+strongly increases with increasing overcoating temperature, which was interpreted by the enhancing diffusion of Er3+ions. Besides, IR-LEDs were fabricated combining commercial red GaAs LEDs.3. PbS/ZnS and PbS/CdS core/shell NCs with different precursor molar of Pb/S were synthesized by a nucleation-doping strategy. In larger the proportion of Pb, the PbS/CdS NCs show excellent near-infrared light-emitting properties, their absorption and emission have a blue shift with increase reaction time, which is due to cation diffusion and exchange in the reaction process, and the alloying is formed at core/shell boundary. In the proportion of Pb is very small, PbS/CdS NCs showing unique visible light-emitting properties, to achieve white light emission.In addition, the spectra of PbS/ZnS NCs also exhibited blue shift.

Related Dissertations

  1. Hydrothermal Synthesis of Oxide Hollow Spheres,TB383.4
  2. Multi-walled Carbon Nanotubes Au _AT_ of Pt, Au _AT_ of Pd core-shell structure of the catalyst preparation and electrochemical properties of,O643.36
  3. A Research and Development for Single Chip Micyoco AVR Usage,TP368.12
  4. The Syntheses and Applications of Nanao Cadmium Sulfide Based on the Green Chemical Concept,O614.242
  5. Core-shell polymer microspheres synthesis, modification and application,O631.3
  6. Electrochemiluminescence Immunosensor Based on Nanocomposite Film of Surface Modified and Assembled CdS Nanoparticles,TP212.2
  7. Preparation of α-Fe2O3/Ag Core/Shell Nanocomposites and SERS Properties,TB383.1
  8. Preparation of Gold and Silver Core-Shell Nanostructure and Their Localized Surface Plasmon Resonance for Sensing,TB383.1
  9. Fabrication of a Uniform Surface Enhanced Raman Scattering Substrate and Its Application,O657.37
  10. P 2 Reparation and Photocatalytic H2 Evolution Study of NiS/CdS Composite Photocatalyst,TQ116.2
  11. Fabrication and Characterization of Nano-ZnO by PLA in Liquid Solution,TB383.1
  12. The Preparation and Sensing Properties of the Fluorescent Chemosensing Material,TP212.2
  13. The Synthesis, Assembly, and Property of Core-shell Structured Noble Metal Nanomaterials,TB383.1
  14. Synthesis and Catalytic Properties of Core-shell Magnetic Nanocomposites,TB383.1
  15. Research on Preparation and Properties of Composite Electrospun Tissue Engineering Scaffolds,Q813
  16. Modification of Talc Powder and Its Reinforcing and Toughening on Recycled Polypropylene,TQ325.14
  17. Surface Modification Technology of High Performance Magnetic Absorber,TB304
  18. Studies on Itraconzole Nanocrystal Dry Suspension,TQ463.53
  19. Study on the Preparation of Zeolite with Core-Shell Structure and Indirect Synthesis of Cyclohexanol from Cyclohexene,TQ233.1
  20. Core-shell polyacrylate emulsion and Application Performance Studies,TQ630.4
  21. Templated Fabrication of Polymeric Nanocages Using Polymeric Micelles as Reusable Template and One Pot Condensation Reactions of Alcohols and Ketones,TQ203

CLC: >
© 2012 www.DissertationTopic.Net  Mobile