Regulation Of Optical Properties Of Halide Perovskite Materials

In recent years,organic-inorganic hybrid perovskite shows great application prospects in the field of luminescent material due to relatively high chemical stability and regulation of efficient luminescence performance.In this paper,a series of organic-inorganic hybrid perovskites were prepared.Through the change from the molecular level two-dimensional（2D）perovskite‘thickness’as well as the preparation of perovskite heterojunction,regulation of the optical properties of the perovskite was achieved.The specific work contents are as follows:（1）Twelve kinds of organic-inorganic hybrid perovskites were synthesized from benzylamine halide and lead halide.The general structure formula is（R-XPMA）₂Pb X₄,（R stands for 2,3,4 position substitution,PMA=benzylamine,X=Cl,Br）.The structure and morphology of compounds prepared were characterized and analyzed.The optical properties were studied.Emitting mechanism of perovskite materials was researched by using the variable temperature fluorescence.The results showed that with the reduction of temperature,the self-trapped excitons tend to be free excitons,leading to stronger fluorescence intensity,peak width narrower and larger stokes shift.（2）With ultrasonic assisted technology,twelve kinds of organic-inorganic hybrid perovskites prepared were exfoliated.The structure and morphology of the exfoliated compounds were characterized and optical analysis was conducted.The results showed that compared with the precursors,the fluorescence emission peak of compounds 1-6showed a certain red shift after stripping,while the fluorescence emission position of compounds 7-12 showed a certain blue shift after stripping.This experimental result provides research ideas for the regulation of optical properties of layered perovskite materials.（3）Six kinds of compounds were assembled into the heterojunction with the complex[Fe（NCS）₂（1,3-bpp）₂]₂,[1,3-bpp=1,3-bis（4-pyridyl）propane]two dimensional nanosheets by mechanical stirring method.The morphology and composition of the heterojunction were characterized and the optical properties of the heterojunction were studied.The results showed that the fluorescence emission peak shape and emission position of the assembled heterojunction changed compared with the matrix material.