Research On Improving The Fluorescence Performance Of All-inorganic Perovskite Quantum Dots Based On Cation Doping

All-inorganic perovskite quantum dots(CsPbX3)have important applications in light-emitting diodes(LEDs),solar cells,displays,photodetectors,and lasers due to its advantages such as good electrical transmission characteristics,tunable wavelength of light emission,full-spectrum emission of visible light,narrow full width at half-maximum(FWHM)and high photoluminescence quantum yield(PLQY).However,the photoluminescence quantum yield of CsPbCl3 blue quantum dot is very low(less than 5%),and the photoluminescence quantum yield of CsPbI3 red light quantum dot is low as well(about 70%).In this paper,Rb+ ion was doped into CsPbCl3 blue light quantum dot and CsPbI3 red light quantum dot.The surface of quantum dots can be passivated by Rb+ ion doping,and the probability of non-radiative transition reduced,so the photoluminescence lifetime became longer and the surface defects reduced.The defect reduced,thereby increasing the photoluminescence quantum yield of the quantum dots.The main research contents are as follows:(1)The Rb+ ion was successfully introduced into the CsPbCl3 quantum dot by an improved thermal injection method,and the site of the Cs+ ion was partially substituted by Rb+ ion.The morphology characterization was carried out by TEM,and the particle size statistics were carried out,it was found that the particle size of quantum dot increased after Rb+ ion doping.The phase characterization was carried out by XRD,the cubic phase structure of CsPbCl3 quantum dot was maintained after Rb+ ion doping but lattice contraction occurred.The elemental analysis was carried out by EDS and XPS,which proved that Rb+ ion was successfully incorporated into CsPbCl3 quantum dot.The spectral characterization was carried out by absorption,emission and transient photoluminescence spectroscopy,through the optimization of Rb+ ion doping concentration,the optimum doping concentration of Rb+ ion was 9%.It was interesting to observe that the photoluminescence quantum yield of CsPbCl3 quantum dot improved from 5.7%to 13%,the absorption and emission peaks shifted to short wavelength,the full width at half-maximum became narrower,and the photoluminescence lifetime extended from 4.2 ns to 10.2 ns.Further investigation on the luminescence dynamics of the quantum dots revealed that the enhanced photoluminescence quantum yield and the narrowed full width at half-maximum resulted from the reduced surface defects in CsPbCl3:Rb quantum dot,and the prolongation of photoluminescence lifetime resulted from the surface passivation of quantum dot after Rb+ ion doping,which reduced the probability of non-radiative transitions.This work improves the photoluminescence performance of CsPbCl3 blue light quantum dot.(2)Rb+ ion was also doped into CsPbI3 quantum dot by the improved thermal injection method,which found that it was similar to CsPbCl3:Rb quantum dot.Through the optimization of Rb+ ion doping concentration,the optimum doping concentration of Rb+ ion was 9%.It was interesting to observe that the photoluminescence quantum yield of CsPbI3 quantum dot improved from 75.2%to 89%,the absorption and emission peaks shifted to short wavelength,and the photoluminescence lifetime extended.The absorption and emission peaks of the CsPbl3:Rb quantum dot shifted to short wavelength,resulting from the lattice substitution of Cs+ ion to Rb+ ion.Further investigation on the luminescence dynamics of the quantum dots revealed that the enhanced photoluminescence quantum yield resulted from the reduced surface defects in CsPbl3:Rb quantum dot,and the prolongation of photoluminescence lifetime resulted from the surface passivation of quantum dot by Rb+ ion doping,which reduced the probability of non-radiative transitions.This work improves the photoluminescence performance of CsPbl3 red light quantum dot.