Study On The Controllable Preparation And Optical Properties Of Aminovaleric Acid Based Two-dimensional Perovskite

In recent years,with the continuously explore of two dimensional organic-inorganic perovskite materials,perovskites with Pb-Br and Pb-Cl based have attracted the attention of the whole research community due to their excellent light emission properties and good stability in air,however,the research on the synthesis of stable white light emission perovskites is still in the primary stage.In the synthesis method,the problem of long time consuming and tedious operation is common,and the toxicity of organic solvents is also one of the urgent problems.Based on this situation,this work focuses on the development of a simple and environmentally friendly synthetic method for the preparation of two-dimensional perovskite materials with white light emission.In this work,the influence of halogen doping on the luminescence properties of two-dimensional perovskite was first investigated,and expect band gap regulation through halogen doping to obtain perovskite materials with white light emission.The 5-aminovaleric acid（AVA）with bifunctional groups was used to gradually replace bromine with chlorine element based on two-dimensional monolayer AVA₂Pb Br₄ perovskite to realize the emission from blue violet to white light,and the AVA₂PbCl₄ perovskite with white light was obtained.This result opens up new channel for further development of white-light-emitting perovskite.Next,because the synthesis methods of these perovskite film materials have the problems of complicated operation and expensive raw materials.Therefore,a simple synthesis method of two-dimensional perovskite materials is proposed,which is in situ tailoring of three-dimensional perovskites with zwitterionic 5-aminovaleric acid to successfully fabricate AVA（MAPbCl₃）_n perovskites.The use of AVA of bifunctional groups can,on the one hand,reduce the structural dimensions of perovskites,on the other hand,effectively regulate the morphology of the perovskites and promote the formation of their nanostructures morphology.Based on the above conclusions,the Pb-COO^-coordination-induced exchange-exfoliation mechanism is further proposed to illustrate the formation process of mixed dimensionoal perovskites.Finally,because organic solvents are used in the synthesis of AVA（MAPbCl₃）_nperovskites,and these organic solvents are harmful to the environment and human health.Therefore,in this paper,the bifunctional two-dimensional perovskite AVA₂PbCl₄ was prepared directly by using deionized water as solvent in the process of synthesis.The perovskite of AVA₂PbCl₄ prepared by deionized water has the same optical band gap and broadband white light properties as the conventional perovskite AVA₂PbCl₄ prepared by organic solvent,but it has better crystallinity and can achieve a photoluminescence quantum yield of 4.3%.This synthetic method of water as solvent effectively avoids environmental pollution and human health problems caused by organic solvent.In addition,the bifunctional perovskite synthesized with water as solvent has stronger luminescence intensity and higher efficiency than the monofunctional perovskite.Briefly,in this paper,the two-dimensional AVA₂PbCl₄ perovskite with white light emission is obtained by halogen doping,and then the synthesis process of white light emission perovskite is simplified.Finally,it is proved that using water as solvent improves the crystallinity of perovskite and achieves good luminescence properties.