| In recent years,organic inorganic layered perovskite have received much attention for their excellent electrical and optical properties and film forming abilities.At the molecular level,organic-inorganic layered perovskite materials is made of organic component and inorganic component assembled by chemical method.The organic layers and inorganic layers are alternately arranged in layered perovskite structure,and organic layers are bonded with inorganic layers by molecular bond.Therefore,perovskite materials have natural quantum well structure,and the structure can be self-adjusted when distorted.The unique properties of organic inorganic layered perovskite materials provide the possibility of its wide applications in the field of optoelectronics.In this study,(R-NH3)2PbX4(X=Br?I)films were prepared by spin coating method,where phenylethylamine,benzylamine,propylamine and butylamine were used as organic precursors respectively.We successfully obtained organic-inorganic layered perovskites,and systematically studied effects of preparation conditions on their properites.We studied optical properites of(R-NH3)2PbX4 system thin film.The influence of the change of inorganic elements halogen ions,annealing temperature,the change of organic element concentration and the change of film layer number on the optical properties of thin films were investigated respectively.We found that in this system,the exciton absorption peak wavelength and emission peak wavelength occurred obvious red shift with the change of inorganic element halogen ions(X=Br,I)species.Film absorption peak wavelength and emission peak wavelength have undergone slight changes with the change of annealing temperature and organic element concentration in the experiment.At the same time,as the increase of the number of film layers,the photoluminescence properties of the materials appeared obvious red shift,but for more than three layers,the optical properties of the films had not too big change.For(C4H9NH3)2PbX4 films,the optical properties of the films with different inorganic substrate show great change.In addition to we also calculate the average lifetime of the films by measuring the fluorescence lifetime of the films.We found that the magnitude of fluorescence lifetime of layered organic-inorganic perovskite thin films is approximately microsecond,the fluorescence lifetime of the films change with the concentration of organic elements,annealing temperature,inorganic elements halogen species and organic elements species.The effect of annealing temperature on the crystal structure of the films during the process of film preparation was investigated by XRD test.The results show that the heat treatment process is crucial to the formation of the crystal structure of the films.With the increase of annealing temperature,diffraction peak intensity of film and the degree of crystallinity increased,low temperature annealing temperature promoted the formation of crystal structure of perovskite material,and annealing temperature of any materials should not too high or too low,Too high annealing temperature will lead to the decomposition of film,and the organic component in the structure will be decomposed until lost.When the annealing temperature is too low,the crystallinity of film is reduced,and it's not conductive to the evaporation of organic solvents in the preparation process.In addition,the inorganic elements and halogen ion species in perovskite materials also have a great influence on the crystal structure of the films.With the change of halogen species,the structural phase of the films will change accordingly.By means of(FDTD)finite-difference time-domain simulation,the MATLAB software is used to simulate the electric field distribution in the cavity of 2D/3D perovskite crystal resonator.By changing the excitation source in the resonator(five kinds of excitation sources)and changing the length and width of the resonant cavity,the corresponding distributions of the simulated electromagnetic fields were obtained. |
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