Synthesis And Third Order Nonlinear Optical Properties Of CsPbBr₃/Ti₃C₂ Composites

In the 21st century,with the rapid development of science and technology,nonlinear optics plays an indispensable role and is widely used in research fields such as optical storage and optical information processing.In this context,researchers’requirements for the performance of nonlinear optical materials are gradually increasing.To further develop,the key lies in exploring new nonlinear optical materials with excellent nonlinear optical properties.Perovskite materials are a class of materials similar to calcium titanate in crystal structure.Due to their significant advantages such as narrow half peak width,high carrier mobility,and band adjustability,they are widely used in fields such as lasers and solar cells.However,there are seldom researches in the field of nonlinear optics at home and abroad.In this thesis,the cesium lead bromide（Cs Pb Br₃）in perovskite and its composite material are used as research objects to investigate their third-order nonlinear optical properties.In this thesis,cesium carbonate and lead bromide were synthesized into Cs Pb Br₃ material by thermal injection method using octadecene as solvent,assisted by ligand oleamine and oleic acid.Then,Cs Pb Br₃/Ti₃C₂ composite material was obtained by growing it on Ti₃C₂ material by thermal injection method.The microscopic morphology of the material was characterized by transmission electron microscope,X-ray diffractometer,ultraviolet visible spectrophotometer and fluorescence spectrometer.The results show that the Cs Pb Br₃ material is cubic structure with size of about 15 nm and regular and dense arrangement.About Cs Pb Br₃/Ti₃C₂ composite material,the granular Cs Pb Br₃ material grows on the surface of the lamellar Ti₃C₂ material with obvious structural layers and increasing the specific surface area.The synthesized Cs Pb Br₃material and Cs Pb Br₃/Ti₃C₂ composite material were prepared into organic glass with different contents.The linear absorption spectra of samples were measured by Ultraviolet Visible Spectrophotometer.The results show that the samples are evenly dispersed and have good light transmittance.The nonlinear absorption characteristics of the samples were investigated by open-aperture Z-scan technology.The results showed that Cs Pb Br₃/PMMA organic glass had transition from saturable absorption to reverse saturable absorption:The sample exhibits saturable absorption characteristics at low energy.With the increase of input energy,saturable absorption changes to reverse saturable absorption.By further increasing the input energy,the sample fully exhibits reverse saturable absorption characteristic.The（Cs Pb Br₃/Ti₃C₂）/PMMA organic glass also exhibits transition from saturable absorption to reverse saturable absorption.At the same input energy,its nonlinear absorption coefficient is greater than that of Cs Pb Br₃/PMMA organic glass.The closed-aperture Z-scan results show that all samples exhibit self-defocusing effects.At the same time,the optical limiting characteristics of the samples were investigated.The optical limiting thresholds(F_th)of Cs Pb Br₃/PMMA and（Cs Pb Br₃/Ti₃C₂）/PMMA organic glasses were6.4 J/cm² and 3.1 J/cm²,respectively.The above experiments have broadened the research on optical aspects of Cs Pb Br₃,which is conducive to its wider application.Moreover,Cs Pb Br₃/Ti₃C₂ composite material exhibits more excellent nonlinear optical properties due to the synergistic effect between Cs Pb Br₃ material and Ti₃C₂ material,which has potential application value in the field of laser protection.