Photoelectric Properties And Stability Of All Inorganic Halide Perovskite Fluorescent Materials

Since the in-organic halide perovskite quantum dots have the characteristic such as visible light range adjustment,narrow emission spectrum,regulation of broad spectrum and ultra-high fluorescence quantum yield,they are widely used in solar cells,backlight display LED,lasers,photo detector and other photoelectric devices.For inorganic halide perovskite materials,the characteristics of the ionic crystal led to its poor stability in the polar environment,and the organic ligands inhibit quantum dot material grain and will easily be separated,which increase its surface defects.It will be shown generally that its ionic crystal and the separation of the organic ligand leading to halogen atoms vacancy defects and grain fusion make a bad effect on their original fluorescence properties under the humid air environment.In order to improve the stability of the system,this paper will be started from two dimensions:the influence of Te doping on the stability of perovskite was systematically studied by improving the Pb-X chemical bond which is easy to break;from the point of view of passivating the high-energy surface of perovskite and protecting the crystal structure by surface coating,the isolation between water oxygen and the surface of perovskite can be realized by means of silanization on the surface,so as to further improve the stability of perovskite quantum dots.Finally,based on the optical properties of perovskite quantum dots itself and the improved environmental tolerance,the application of All-white LED is prepared.The specific work are as follows:1.Fluorescence properties and stability of quantum dots materials by CsPbBr₃/Pb Te composite.Perovskite quantum dots were prepared by the hot injection method,and the doping of perovskite quantum dots by tellurium element were realized through organic solvent.The particle size of CsPbBr₃/Pb Te is between 20 and 23 nm and the doping of Te elements causes the formation of Pb Te on the surface of quantum.The optical and physical properties,stability and the microstructure of the materials were characterized systematically though XRD,PL,UV,XPS,TEM,TGA and so on.As the result,it is found that the radiation transition efficiency of quantum dots is improved instead of the reducing of the in-radiation transition efficiency due to the doping of a small amount of Te element;with the enhancement of the Pb-Br chemical bone,the surface of perovskite were passivated which improved the environmental stability significantly.After 60 hours of storage in air,the PL strength of CsPbBr₃/Pb Te remains over 40%,while the PL strength of the undoped perovskite is only30%.2.Fluorescence properties and stability of CsPbBr₃quantum dots by SiO₂Coating Method.Also,the perovskite quantum dots were prepared by the hot injection method too.Organic silicone matrix tetramethoxysilane was added into the quantum dots after washing,and hydrobromic acid was used as the hydrolysis catalyst.Experimental results show that the presence of hydrobromic acid can not only accelerate the decomposition of organic silicate,but also supplied the composition of Br element,which ensure that the perovskite will not be decomposed and will not lead to fluorescence quenching due to the equilibrium reaction of the loss of Br.The perovskite CsPbBr₃@SiO₂ obtained conforms to the material system as we need and presents a structure of multiple perovskite quantum dot polymers coated with silica.Compared with the undoped perovskite,the strength distribution of PL in powder form and dispersed in solvent form remained more than 50%and 70%after 96 hours in the air,while that of pure perovskite only remained 20%and 30%,showing better environmental tolerance.In term of the thermal stability,its decomposition temperature is 100?higher than that of pure perovskite samples.More importantly,CsPbBr₃@SiO₂ existed in the deionized water for5 hours,while the undoped perovskite lasted for only 20 seconds before decomposition and quenching,showing good water resistance that lays a good technological foundation for quantum dots in the subsequent industrial water-based solvent process.3.Based on the improved Te-doped perovskite,the KSF red powder were used on the InGaN chips to combine into the white LED.The white LED based on RGB colored light synthesis,solved the traditional LED problem which are excess of blue light,lack of green light and long wavelength red light,realized the display color gamut wider than the NTSC standard.CIE chromatograms of synthetic white light coordinates for the object of(0.31,0.35).4.Based on above work,a white LED based on total perovskite component is realized.CsPbBr₃ and Cs Pb I₃ perovskite quantum dots were prepared by hot injection method,and the two kinds of perovskite with different fluorescence characteristics were silanized on the surface.Based on the combination of the two kinds of quantum dots coated on the surface and the InGaN chip,an All-white LED with RGB light synthesis was prepared,and the white light coordinate is(0.31,0.33).