Controliable Synthesis And Characterization Of PbS And PbSe Quantumn Dots

Because the electron energy of semi-conductor materials is pretty low and de Broglie wave length of them is very long, their nano material can be hopefully applied in the fields of electron, optics and biology, etc. Among these materials, the nanomaterials ofâ…¡-â…¥semiconductors have many important physical and chemical properties, and have a broad range of meaningful applications in many fields. PbS and PbSe nanocrystals have very high photosensitive absorption and their emission wavelength is in the near infrared region. More important, their energy gap can be controlled through changing the sizes and shapes of these nanoparticles. The current synthesis methods of PbS and PbSe nanocrystals have many shortcomings such as low yield, complicated process and using toxic reagents.This thesis focuses on developing new methods for the synthesis of PbS and PbSe nanocrystals. We have synthesized sizes-and shapes-controlled quantum dots by tuning the molar ratio of reactants, reaction temperatures and time, etc.My major work is as followsmain results are list below:1. Using hot solution injection method, we synthesized PbS quantum dots with different diameters and different surface ligands. The near infrared absorption properties and electrical properties in FET devices were studied.2. We developed a new method for synthesizing spherical and cubic PbSe nanocrystal. The near infrared optical properties of the nanocrystals were studied. We also obtained Pb-PbSe metal-semiconductor nanomaterials with different structures and hollow PbSe nanocrystals by utilizing the new method.3. We improved the synthesis method of CdSe quantum dot, and prepared spherical and treelike CdSe nanoparticle with relatively large sizes.The optical properties such as absorption and fluorescence were investigated.4. We prepared oil-phase Au nanoparticle by using a phase transfer method. This multiphase synthesis method is simpler than previous reported methods, and the produced oil-phase Au nanoparticle are highly uniform.