Preparation And Application Of Blue Perovskite With High Stability

In recent years,perovskite materials have received a lot of attention due to their unique and excellent optoelectronic properties such as large absorption coefficient,adjustable band gap,high brightness,high color purity,wide color gamut,high defect tolerance,and simple preparation method.Perovskite materials have been widely used in various fields such as solar cells,light-emitting diodes,lasers,X-ray imaging,and photodetectors.It is noteworthy that after the development in recent years,the external quantum efficiency of light-emitting diodes made of perovskite materials has exceeded20%.However,the stability problems of perovskite materials,especially the sensitivity to factors such as water,light,heat,oxygen,and organic solvents,greatly limit its further application.Although researchers have used different methods to improve the stability of perovskite materials in recent years,the preparation of perovskite materials with good stability to water,light,heat,oxygen,organic solvents and other elements at the same time is still it is hard.Moreover,most of the stable perovskite materials that have been reported are concentrated in the green and red bands,so it is urgent for the display field to prepare blue perovskite materials with high stability.In view of the above problems,this article synthesizes a highly stable perovskite material with continuously adjustable wavelength in an alkaline atmosphere.At the same time,this method is also suitable for all-inorganic halide perovskite materials(Cs Pb Br_1.6Cl_1.4).The research results obtained in this paper are as follows:（1）By synthesizing the perovskite material in an alkaline atmosphere,the MAPb Br_xCl_3-x quantum dots are wrapped in Pb（OH）Br to synthesize the highly stable crystal MAPb Br_xCl_3-x@Pb（OH）Br.In addition,by simply adjusting the ratio of HCl and HBr,the luminescence of MAPb Br_xCl_3-x@Pb（OH）Br can be adjusted in the range of 435-485nm.（2）Experiments show that the cubic MAPb Br_xCl_3-x is formed into rectangular MAPb Br_xCl_3-x@Pb（OH）Br through redox reaction with the aid of methylamine vapor.At the same time,experimental results show that the generated MAPb Br_xCl_3-x@Pb（OH）Br has good water,light,heat,and organic solvent stability.After immersing MAPb Br_xCl_3-x@Pb（OH）Br in water for 6 months,the crystals are still With bright luminescence.Because the Pb（OH）Br formed on the surface has good chemical inertness,MAPb Br_xCl_3-x@Pb（OH）Br also has good resistance to anion exchange.（3）MAPb Br_xCl_3-x@Pb（OH）Br perovskite powder and PDMS are mixed as a conversion layer to prepare UV pumped LEDs that emit light at 435nm-485nm.At the same time,experiments show that the LEDs have good stability and can operate stably in a humid environment for more than 8 hours,and the brightness exceeds 1000 cd/m².At the same time,this method has universal applicability.Cs Pb Br_1.6Cl_1.4@Pb（OH）Br can be synthesized through the same method,and this sample also has good stability.