The Luminescence Properties Of All Inorganic Perovskite Quantum Dots CsPbX₃ Regulated By Lanthanide Compounds

All-inorganic perovskite quantum dots（Pe QDs）CsPbX₃（X=Cl,Br,I）have come into the field of vision owing to their excellent optical properties,including high PLQY,tunable wavelength with halogen ion composition,narrow FWHM and so on.In order to further enhance the photoelectronic properties of the Pe QDs,rare earth ion doping is an effective regulatory method.Through the direct doping of rare earth ions,the 4f level of rare earth can be combined with the host,making the host have the characteristics of multi-mode fluorescence emission and multi-excitation channels.However,it is not easy to achieve high concentration doping of rare earth ions in the Pe QDs due to the difference of ion size and valence.In order to promote the regulation of rare earth ions on Pe QDs,we can solve the problem by preparing rare earth/Pe QDs composites.Based on this,this thesis takes the Pe QDs modulated by rare earth compounds as the research object,with the aim of improving its stability,luminous efficiency,expanding its upconversion and multi-channel emission functionality.First,the upconversion luminescence is realized by combining rare earth doped upconversion nanoparticles with Pe QDs by using photocuring resin as auxiliary matrix.Secondly,in order to solve the problem of low doping concentration of rare earth ions,we combine rare earth metal organic framework materials（Ln MOFs）with Pe QDs,realizing the stable luminescence of Pe QDs with the control of high concentration of rare earth ions.In addition,the Pe QDs/Ln MOFs luminescence properties under high pressure is further studied.The main findings of this paper are as follows:1.The multi-color UCNPs/Cs Pb(Br_1-xI_x)₃ for upconversion luminescence and dual-modal anticounterfeiting.In order to realize the high efficiency upconversion luminescence of Pe QDs,we have combined it with upconversion nanoparticles(UCNPs,core-shell Na YF₄:25%Yb³⁺,0.5%Tm³⁺@Na YF₄)by using light-cured resin（UVCR）as auxiliary substrate,and the the UCNPs/CsPbX₃@UVCR with excellent upconversion luminescence is obtained.At980nm excitation,the UCNPs/CsPbX₃@UVCR has a stable and bright upconversion luminescence.Compared with the nonlinear upconversion of multi-photon absorption in perovskite,UCNPs/CsPbX₃ achieves lower power density excitation by using the UCNPs as the physical energy transfer level,meeting the demand for multi-color upconversion luminescence in optical applications.In addition,the UCNPs/CsPbX₃@UVCR shows excellent water and air stability,which can be employed as multicolor fluorescent ink for screen printing security labels.2.High pressure optical properties of the synergistic luminescent CsPbBr₂Cl@EuMOFs nanocomposites.In order to realize the multi-channel luminescence of Pe QDs regulated by rare earth ions,the CsPbBr₂Cl@EuMOFs nanocomposites are prepared by an in situ synthesis using Cs ions as precursors in this work.The morphological and optical properties of the prepared CsPbBr₂Cl@EuMOFs have been characterized in detail.We find that CsPbBr₂Cl@EuMOFs both have the excellent PL properties of CsPbBr₂Cl Pe QDs and the unique narrow-band emission of Eu³⁺.Furthermore,we studied the evolution of CsPbBr₂Cl@EuMOFs fluorescence under high pressure and found the remarkable fluorescence enhancement of CsPbBr₂Cl@EuMOFs.By analyzing the PL emission spectra and exciton dynamics,we infer that the luminescence mechanism of the CsPbBr₂Cl@EuMOFs is the synergistic luminescence,and the luminescence mechanism is greatly stable even under high pressure.In general,the fluorescence yield and luminescence stability of Pe QDs can be effectively improved by combining with Ln MOFs.Also,the problem of low doping content of rare earth ions in the lattice structure of Pe QDs is solved perfectly.