Preparation And Afterglow Properties Study Of Two-Dimensional Metal Halide Perovskites

Organic afterglow materials with a much longer emission lifetime show great application potential in emerging fields,such as flexible intelligent information encryption,optical anticounterfeiting,and biological imaging.Two-dimensional（2D）metal halide perovskites display significant advantages in realizing organic afterglow due to their variable structure,tunable composition,low defect density and strong light absorption ability,and tunable exciton species.But so far,almost no 2D metal halide perovskite with high-efficiency and long lifetime afterglow characteristics is reported,and the available afterglow color is usually singular.In this thesis,a series of novel 2D metal halide perovskites with excellent afterglow properties are designed and prepared by adjusting the composition and structure of inorganic layers and the types of organic layers.The specific research contents are as follows:（1）In this work,two new 2D metal halide perovskites as 4MPPC and 3MPPC were successfully prepared by choosing PbCl₂ as inorganic layer and phenethylamine derivatives with methoxy group,namely 3-methoxy phenylethylamine（3MPEA）and 4-methoxy phenylethylamine（4MPEA）as organic layer.The afterglow lifetime of 4MPPC is up to 480 ms,which is the longest lifetime in the reported 2D metal halide perovskite afterglow materials systems currently.Further studies show that the hydrogen bonds between the organic and inorganic layers as well as the interactions between organic molecules enhance the rigidity of the material and effectively restrict the movement of organic molecules.Meanwhile,inorganic layer effectively isolate oxygen.The cooperative effect greatly reduce the non-radiative transition and quenching of triplet excitons,and improve the stability.Based on the excellent afterglow performance and good stability,the 4MPPCs shows great potential in data encryption and afterglow LED devices.（2）In this work,two novel 2D metal halide perovskite afterglow materials,P-MACC and P-EACC,were synthesized by choosing CdCl₂ as inorganic layer and piperonylamine derivatives,namely piperonylamine（P-MA）and homopiperonylamine（P-EA）as organic layer.The lifetime of P-MACC and P-EACC are 224 ms and 579 ms,respectively.Single-crystal analysis indicates that the alkyl chain length results in different stacking arrangements of P-MA and P-EA in inorganic layers.The longer lifetime of P-EACC is due to more effectiveπ-πstacking of adjacent P-EA cations.In addition,both P-MACC and P-EACC display temperature-dependent color-tunable afterglow emission characteristices.（3）Based on the P-EACC,synthesized in the previous chapter,this work successfully synthesized a novel red 2D metal halide perovskite afterglow materials by simply doping Mn²⁺ions.After in-depth research,it is found that the triplet state of P-EACC can transfer energy to Mn²⁺ions,promoting Mn²⁺ions a long-lived and high-efficient red afterglow emission.By varying the doping amounts of Mn²⁺ions????曅??谘?礶??灪?済餍?欢绅???墫tent is about 20%,and the lifetime and efficiency of the material are 343 ms and 44.11%,respectively.