The Preparation Of Nanofluorescence Materials By Supersaturated Recrystallization

Nanocrystals have extensive and important application prospects in various fields such as fluorescent probes,solar cells and optoelectronic devices.Because of their unique physical and chemical properties.So far,most of the methods are reported high temperature,inert gas protection,and hot injection of the front body.The preparation of nanocrystalline production is generally low,and it is difficult to produce large-scale industrial production.In this paper,a novel supersaturated recrystallization method is used to prepare CdS quantum dots.This method has the advantages of low synthesis temperature,rapid reaction and easy to operate.Meanwhile,the method can also be used for the preparation of rare earth doped nanocrystals,and the prepared nanofluorescent materials have the advantages of good crystallinity and high quantum efficiency.In the first part,the high quality transition metal doped CdS quantum dots were successfully prepared by supersaturated recrystallization.The effects of Sn²⁺,Sb³⁺,Ni²⁺,Mn²⁺and Cu²⁺doping on the luminescent properties of CdS quantum dots were discussed.Due to the doping of transition metal ions,the energy band of semiconductor has changed.The emission spectrum can be continuously adjusted from green to yellow,orange and red.The effect of different synthetic temperature on the fluorescence properties is explored.When the temperature increases in a certain range,the emission spectrum is red shift.This phenomenon can be attributed to the quantum size effect.Finally,in order to explore the practical application of quantum dots,we applied the prepared green CdS quantum dots and red light CdS:Cu quantum dots and blue light chips to W-LED.The luminescent devices prepared have high luminescence efficiency?42lm/w?and high chromatic coefficient?Ra=80?,which are higher than those of the same kind.In the second part of this paper,a series of CaMoO₄ nanofibers doped with rare earth?Tb,Dy,Sm,Eu?are prepared by similar methods.The length range of the nanofibers is about 40-70 nm,the width is about 2 nm,and the nanofibers are dispersed evenly,and the crystallinity of the nanofibers is good.Then through the co doping of two kinds of rare earth ions?Tb/Eu,Tb/Sm,Tb/Dy,Dy/Eu?,we can realize the continuous and adjustable light color from green light to Huang Lvguang,orange light and red light.At the same time,the obtained nanofibers still maintain good crystallinity,strong luminous intensity and high quantum efficiency.The energy transfer between Tb and Eu ions is demonstrated.Finally,the CaMoO₄:Tb,CaMoO₄:Eu,CaMoO₄:0.05Tb,and Eu nanofibers are used for green,red and white light emitting devices,which exhibit high operating stability and luminous efficiency.The third part controls the amount of surfactant added to prepare a series of rare earth doped NaY?MoO₄?₂ nanocrystals.The nanocrystals have adjustable size,uniform morphology,strong luminescence efficiency and different volumes of oleamine.The morphology of nanocrystals can be adjustable from dot to quasi square to grain shape,and the diameter of the particles can be changed in the range of1-20nm.We have studied the luminescence intensity of NaY?MoO₄?₂:Eu with different morphologies.We think that the different luminescence intensity is mainly due to the crystallization of different morphologies and the effect of surface defects.At the same time,a series of Tb and Eu Co doped nanocrystals are also synthesized,and the energy transfer between the two ions is also characterized and analyzed in detail.We use the single matrix NaY?MoO₄?₂:0.05Tb,0.04Eu nanocrystals to stabilize the efficient white light device?64lm/w?.The series of rare earth doped nanocrystalline materials show great potential in the field of photoelectricity and biology.