Study On The Preparation,Ion Doping And Encapsulation Of All Inorganic Perovskite Nanocrystals Based On The Microfluidic Technology

In recent years,with the wide application of perovskite nanomaterials in solar cells,light-emitting diodes,photodetectors and other fields,perovskite materials have been greatly studied by scientists.As an important branch of inorganic perovskite materials,all inorganic perovskite nanocrystals have attracted great attention due to their excellent optical properties such as high fluorescence quantum yield,narrow fluorescence emission spectrum,tunable fluorescence wavelength with different halogen doping.However,at present,the main preparation method of all inorganic perovskite nanocrystals is still the high temperature hot injection method.The preparation conditions are high temperature and inert gas protection,which can not achieve continuous and controllable preparation.Moreover,the luminescent properties of all inorganic perovskite nanocrystals in the external environment are extremely unstable,which greatly limits their practical application.Microfluidic technology is a kind of technology that can accurately control and process fluids.In recent years,it has been widely used in the flow reaction and physical encapsulation in liquid phase.As an efficient micro reactor platform,microfluidic device has the advantages of high integration and high controllability compared with the traditional experimental platform.In view of the problems in the preparation and properties of the above-mentioned all inorganic perovskite nano materials,this paper proposes an automatic micro reactor based on microfluidic technology,which realizes the synthesis of all inorganic perovskite nanocrystals and ion doped all inorganic perovskite nanocrystals at room temperature without inert gas protection.Based on the microfluidic droplet preparation technology,polymer encapsulation was used to improve the luminescent stability of all inorganic perovskite nanocrystals.X-ray diffraction was used to characterize the crystal structure of all inorganic perovskite nanocrystals;transmission electron microscopy was used to characterize the lattice fringes of all inorganic perovskite nanocrystals;UV-Vis spectrophotometer was used to characterize the absorption spectrum of all inorganic perovskite nanocrystals;fluorescence spectrometer was used to characterize the emission spectrum,quantum yield and fluorescence lifetime of all inorganic perovskite nanocrystals;fluorescence microscope was used to characterize the fluorescent images of all inorganic perovskite nanocrystals.The specific work is as follows:1.The Cs Pb Br₃all inorganic perovskite nanocrystals were synthesized by antisolvent method in capillary microfluidic chip at room temperature and without inert gas protection.In the range of 1:10-1:600,all inorganic perovskite single crystals with high quality can be prepared.The typical monoclinic crystal structure of Cs Pb Br₃all inorganic perovskite nanocrystals prepared at different flow rates has an average size of about 17 nm,a fluorescence emission wavelength of about 517 nm and a fluorescence lifetime of 9-10 ns.2.All inorganic perovskite nanocrystals doped with Ce³⁺were successfully prepared by multichannel capillary microfluidic chip.The Cs Pb Br₃all inorganic perovskite nanocrystals with different Ce³⁺doping concentration were obtained by changing the flow rate ratio of the reactant.The results show that Ce³⁺doping does not destroy the original crystal structure of Cs Pb Br₃nanocrystals,and Cs Pb Br₃nanocrystals with different Ce³⁺doping concentrations have the same emission wavelength and half peak width.The doping concentration of Ce³⁺is up to 1%.Ce³⁺doping can increase the quantum yield of Cs Pb Br₃all inorganic perovskite nanocrystals from 67.5%to 86.7%.3.In the capillary microfluidic chip,all inorganic perovskite nanocrystalline microspheres were prepared by combining droplet microfluidic technology with light curing technology.The size of the microspheres can be controlled by adjusting the flow rate.The radius of the microspheres is between 75-113?m.the relationship between the radius and the flow rate is a power exponential function.The microsphere has monodispersity and the size difference coefficient can be controlled at 0.152%.The light-emitting stability of all inorganic perovskite nanocrystals in the light,heating,ultralow temperature and water environment can be significantly improved by the inclusion of microspheres.