Synthesis And Application In LED Of Perovskite Quantum Dots And Metal Clusters

Low-dimensional materials have special physical and chemical properties due to quantum effects and surface effects.Among them,quantum dots and clusters are two low-dimensional materials with special excellent properties.In recent years,the study of inorganic perovskite quantum dot CsPbX3(X=Cl,Br or I)materials has made a leaps and bounds,and it has shown excellent properties in optical and electrical research,such as high fluorescence quantum efficiency Tunable emission spectrum and narrow fluorescence emission peak,etc.,thus becoming a research hotspot in the fields of light-emitting diodes(LEDs),solar cells and photodetectors;However,the narrow fluorescence emission peak of perovskite quantum dots contradicts the wide spectrum requirements of high color rendering white LEDs,and there are serious ion diffusion chemical reactions in the process of mixing multiple colors of perovskite quantum dots to prepare white light,which White LEDs based on perovskite quantum dots still have many problems(ion diffusion and poor stability,etc.)that need to be solved.At present,the scientific research content of clusters is mainly how clusters gradually evolve from microscopic particles(atoms,molecules,etc.),and changes in structure and properties during the evolution of clusters,but there are few researches on the application of cluster devices;In recent years,the luminous efficiency of fluorescent metal clusters has gradually increased,and it has been applied to the fields of LED,ion detection,and cell fluorescence imaging.Among them,the research in the field of white LED is in its infancy,and there are still much physical,chemical,stability,compatibility and other issues that need to be resolved.This paper starts from the perspective of the preparation of perovskite quantum dots and metal clusters and their application in LEDs.Firstly,a set of photoluminescence absolute fluorescence quantum efficiency measuring device is designed and built;then CsPbX3 monochromatic light perovskite quantum dots and Mn2+ doped CsPb(ClxBr1-x)3 bimodal white light perovskite quantum dots are prepared by hot injection method,and the material properties are studied.The bimodal white light perovskite Mineral quantum dots are used as light conversion materials,coated on ultraviolet LED to prepare two primary color white LEDs,and studied the photoelectric properties of the white LEDs;finally,orange Au/Ag clusters are prepared by aqueous solution method,and combined with Au/Ag cluster and blue phosphor,two primary white LEDs are prepared,and the photoelectric properties of the white LED are studied.The specific research content of this paper is as follows:1.Construction and research of photoluminescence absolute fluorescence quantum efficiency measurement system:A set of photoluminescence absolute fluorescence quantum efficiency measurement system is designed and constructed.The system is mainly composed of 4-inch integrating sphere,QE65000 spectrometer,multi-color LED light source,optical fiber,standard light calibration lamp,control computer,etc.The laser fluorescence calibration of the scattered light in the integrating sphere is introduced through the three-step measurement method,and simple data conversion and calculation are applied to it,which can realize the accurate measurement of the absolute fluorescence quantum efficiency of liquid and solid.The fluorescence quantum efficiency of the standard fluorescent material Rhodamine 6G(95%)is measured by this measurement system,and the fluorescence quantum efficiency measured by the integrating sphere three-step method is 96.6%.After several measurements,it is determined that the measurement error range of the system is about ± 2%,and the fluorescence quantum efficiency value measured by the traditional two-step method is 87.5%.The accuracy of the photoluminescence absolute fluorescence quantum efficiency measurement system is verified.2.The preparation of CsPbX3 perovskite quantum dots and its application in LED:CsPbX3 perovskite quantum dots are prepared by hot injection method using cesium oleate precursor solution as injection solution,and oleic acid and oleylamine as surface ligands.By adjusting the halogen element,a perovskite quantum dot with tunable emission wavelength is realized.The rapid change process of the fluorescence spectrum of CsPbX3 quantum dots after mixing is monitored and recorded in real time using a grating spectrometer,the rapid exchange process of halogen anions of perovskite materials is verified,and the effect of ion exchange reaction on the fluorescence of perovskite quantum dots is investigated.Finally,the perovskite quantum dots are coated on the blue LED chip,the monochromatic LED based on the perovskite quantum dots is prepared,and the application of the hybrid quantum dots in the LED is further studied,which laid a research for manufacturing quantum dot white LEDs basis.3.Preparation of Mn2+-doped CsPb(ClxBr1-x)3 bimodal white light perovskite quantum dots and its application in white LEDs:Mn2+-doped CsPb(ClxBr1-x)3 bimodal perovskite quantum dots using hot injection Synthesized by MnCl2 as Mn source,oleic acid and oleylamine as ligand,hydrobromic acid as auxiliary reagent and 1-octadecene as solvent.By adjusting the reaction conditions such as Mn/Pb ratio,CI/Br ratio,amount of hydrobromic acid,the emission wavelength of CsPb(ClxBr1-x)3 matrix fluorescence peak,CsPb(ClxBr1-x)3 matrix fluorescence peak and Mn2+fluorescence peak are adjusted The relative intensity.When the reaction conditions are Mn:Pb=1:5,Cl:Br=7:3,100 ?L hydrobromic acid,Mn2+ doped CsPb(ClxBr1-x)3 bimodal white light quantum dots are successfully prepared.The fluorescence quantum efficiency is 8.06%,and the total fluorescence quantum efficiency of the solid sample is 8.92%.Then,the prepared bimodal white light perovskite quantum dots are coated on the ultraviolet LED to prepare a white light LED,the color coordinate is(0.314,0.336),and the CRI is 62.2.The experimental results show that the double emission peak white light perovskite quantum dots have great application value in the field of white light LED.4.Synthesis of Au/Ag clusters and application research in white LEDs:Chloroauric acid and silver nitrate as raw materials,GSH as reducing agent and stabilizer,reacted at 85? for 3 h to prepare orange with aggregation induction effect Glowing bimetallic Au/Ag cluster.White LEDs are prepared by coating Au/Ag clusters with blue phosphors on ultraviolet LED chips.The color coordinate of the white LED is(0.375,0.385),and the CRI is 88.2.The experimental results show that metal clusters have broad application prospects in white LEDs with high color rendering performance.