Preparation,Optical Properties And LED Applications Of Perovskite Quantum Dots Glass Materials

All inorganic perovskite lead halide cesium?CsPbX₃,X=Cl,Br,I?quantum dots have excellent performance and luminescence properties,such as bright emission and adjustable wavelength,narrow emission spectrum,high luminous efficiency,are promising optoelectronic materials for the light emitting diode,lasers,polarizer,solar cells and photoelectric detectors and other manufacturing technology.CsPbX₃quantum dots can be dispersed in various non-polar solutions,such as n-hexane,toluene,etc.,and can be used as water-based optoelectronic devices for ink.This further indicates that CsPbX₃ quantum dots have a great application prospect in low-consumption lighting.According to relevant reports,the emission wavelength of CsPbBr₃ quantum dots in the entire visible spectrum covers 410-700nm and the highest quantum yield is up to 90%.The colloidal properties of CsPbX₃ quantum dots prepared by thermal injection still have problems of air and thermal instability.Therefore,we added the perovskite quantum dots into more stable glass matrix materials and analyzed their morphology,microstructure and optical properties through some modern tests.The main research contents are as follows:?1?On the basis of previous experiments,CsPbBr₃,CsPbBr_1.5I_1.5 and CsPbI₃ quantum dot glass were successfully prepared at different heat treatment temperatures using the traditional melting and heat treatment technology.In addition,the fluorescence spectrum of the CsPbX₃quantum dots can be tuned from 500 nm to 700 nm.Blue,orange and red fluorescent of CsPbBr₃,CsPbBr_1.5I_1.5,and CsPbI₃ NCs can be observed under the excitation of blue or ultraviolet light,however,the quantum efficiency is not very high,which is 42.5%,15.5%and 17.2%respectively.By combining three kinds of quantum dot glass with blue chip,three LED components with high color purity can be fabricated.Under the excitation of blue chip,the color purity of CsPbBr₃ quantum dot glass is up to 99.6%.?2?The disadvantage of pure quantum dot glass lies in the low quantum efficiency of glass when comparing to the solution.CsPbBr₃ quantum dot glass is taken as the main research object,and two ways are proposed to improve the quantum efficiency of quantum dot glass.The primary improvement approach is to improve the quantum efficiency of CsPbBr₃quantum dot glass by changing the raw material formula and adjusting the molar concentration of quantum dots.Another way is to use heteroatom doping,such as Sn²⁺,Mn²⁺,Rb²⁺and other transition metal ions,Eu³⁺/Eu²⁺rare earth ions,to improve their quantum efficiency.In this paper,the rare earth element Eu with rich energy levels is selected.The effect of improving the quantum efficiency is mainly achieved by changing the concentration of rare earth ions in the glass.It is worth noting that under the excitation of blue chip,quantum dot glass showed fluorescence emission from green to red with the change of europium ion concentration.Through simple composite,four kinds of light-emitting LED simple components were successfully constructed.?3?Europium rare earth ions were introduced into the lattice of CsPbBr_1.5I_1.5,Eu ions are mainly occupied near in Pb site and Br site,the experimental results show that after doping low concentration Eu ions,the quantum efficiency of CsPbBr_1.5I_1.5 quantum dots is effectively improved.This result is because of the doping of Eu ions can introduced the Eu's energy level into perovskite level,the valence electrons can jump into europium part back to the ground state energy level,this process can effectively reduces electron and defect recombination,so as to improve the quantum efficiency of the quantum dots glass.Eu³⁺doped CsPbBr_1.5I_1.5.5 quantum dot glass is a kind of potential red fluorescent glass.When building Ce:YAG-based WLEDs,it can be used as a red fluorescent component to greatly improve its color rendering index which increases from 60.9 to 92.4.