Study On Preparation Of CsPbX₃/Cs₄PbX₆ All-inorganic Perovskite

The all-inorganic perovskite material represented by CsPbX₃ has adjustable band gap,high color purity,high PL and high PLQY,and is considered as a promising and popular material for next-generation lighting and display.Cs₄PbX₆is a perovskite-like material with excellent optical properties and excellent stability.When combined with CsPbX₃ to prepare a CsPbX₃/Cs₄PbX₆ perovskite composite material,it has higher luminescence and better stability than CsPbX₃,which has received more and more attention.Although there have been many reports on the optoelectronic properties of perovskite materials,the rapid and high-quality synthesis of such materials is still challenging.In this paper,high-quality CsPbX₃/Cs₄PbX₆ composite microcrystals were quickly synthesized by the supersaturated recrystallization method and the optimized anti-solvent vapor assisted method.In addition,the CsPbX₃/Cs₄PbX₆ composite microcrystals were studied by optimizing experimental parameters such as the solvent ligand temperature the growth mechanism and luminescence performance of the paper,the research content of this paper is as follows:1.The CsPbBr₃/Cs₄PbBr₆ composite microcrystals were prepared by the supersaturated recrystallization method.Through microstructure characterization,it is found that the prepared microcrystals are grown by large-size Cs₄PbBr₆ encapsulating small-size CsPbBr₃,forming a unique granular mosaic structure.By controlling the addition ratio of the solvent DMF and DMSO,it was found that with the increase of DMSO content,the size of the microcrystals gradually increased,and the content of CsPbBr₃ also increased.The best fluorescence properties were obtained when DMF was 5 m L.Second,the effect of the polarity of the anti-solvent on the product was studied.The experiment found that with the increase of the polarity of the anti-solvent,the size of the microcrystals gradually increased,and the morphology also changed.The composite microcrystals prepared by dichloromethane had the strongest fluorescence intensity.Finally,dichloromethane was used as an anti-solvent to study the influence of the dissolution temperature of the precursor and the anti-solvent temperature on the product.With the increase of the dissolution temperature,the size of the microcrystals gradually increased.After optimizing the comparative experiment,it is found that the product prepared by dissolving the precursor at 50?and using dichloromethane at 50?has the most excellent optical properties.2.The supersaturated recrystallization method is used to prepare lead-less materials and halogen-substituted perovskite materials to realize the control of the luminous peak position.Through the doping of Mn²⁺,Mn:CsPbBr₃ with bright yellow luminescence was obtained.Changing the doping ratio of Mn²⁺changes the luminescence peak position and luminescence intensity of the material.The doping of Mn²⁺reduces the content of Pb²⁺and achieves the goal of reducing lead.In addition,the introduction of I source obtained Cs₄Pb(Br I)₆/Cs Pb(Br I)₃ composite microcrystals.The study found that the introduction of Cs₄Pb(Br I)₆ effectively passivated the defects of Cs Pb(Br I)₃ and improved the luminescence of composite microcrystals.After changing the amount of ligand,it is found that when OA 0.1 m L and OAm 0.1 m L,the fluorescence intensity is the highest.As the amount of ligand increases,the fluorescence intensity of the material decreases.3.The Cs₄PbBr₆/CsPbBr₃ composite microcrystals with hexagonal tower structure were prepared by the anti-solvent vapor assisted method.In this method,the gas-liquid reaction interface is obtained by forming vapor in the anti solvent,and the control of the reaction process is realized.Compared with the microcrystals prepared by the room temperature supersaturation method,they have brighter green emission.The microstructure characterization proved that the prepared microcrystals were Cs₄PbBr₆/CsPbBr₃ composite microcrystals.The absorption spectrum shows that the prepared material has two different absorption peaks,which correspond to CsPbBr₃ and Cs₄PbBr₆ respectively,which proves the coexistence of the two structures.The element ratio of the microcrystals was obtained through the composition analysis,and the analysis indicated that the hexagonal tower-shaped composite microcrystals were composed of Cs₄PbBr₆,and CsPbBr₃was mainly embedded in the matrix of Cs₄PbBr₆as nanocrystals.Subsequently,the influence of Cs₄PbBr₆/CsPbBr₃ composite microcrystals synthesized by OAm and OA was studied.OAm affected the morphology of the product,and OA affected the thickness of the tower structure.Finally,the influence of the evaporation temperature of the anti-solvent was studied.The size of the microcrystals increases with the increase of temperature.When the temperature is too high,the morphology of the microcrystals is not controlled,grows disorderly,and impurity Cs Br is generated.The fluorescence intensity of the microcrystals increases first and then decreases with the increase of temperature.When the temperature is80?,it has the best luminescence properties,and the quantum yield reaches 60.22%.