Design And Preparation Of Organic-inorganic Hybrid 2D Perovskite And Their Photoelectric Properties

Two-dimensional perovskite shows extremely high stability when used in optoelectronic devices,and makes up for the shortcomings of three-dimensional perovskite,so it has been widely studied in the field of optoelectronics.Although the photoelectric application based on two-dimensional perovskite has developed rapidly,due to the limited understanding of its basic physical properties,there are inaccurate measurement of the optical band gap of two-dimensional perovskite,and the detection results of fluorescence spectroscopy are very different,especially in Carrier dynamics,exciton quasi-particles and other aspects are not mature enough,and many aspects need to be further explored.Therefore,this thesis starts with the growth of pure two-dimensional perovskite(PEA)₂PbI₄ high-quality single crystal,through a series of spectral tests on it,the photoelectric physical properties of the crystal were systematically explored,as follows:First of all,this research used constant temperature solvent volatilization method instead of the commonly used cooling method to successfully grow high crystalline quality two-dimensional perovskite(PEA)₂PbI₄ single crystal,and it was carried out by single crystal X-ray diffractometer,fluorescence microscope,and atomic force microscope.Characterization of crystal structure and morphology.Subsequently,we measured the absorption spectrum of the(PEA)₂PbI₄ single crystal using an ultraviolet-visible spectrophotometer.Through further analysis,the Urbach energy E_u=57.1±1.7 me V,which is related to the degree of crystal disorder,is obtained.At the same time,by comparing the Tauc plot method and the Elliott model fitting to expand the discussion of the optical band gap calculation,the Elliott model fitting can distinguish the exciton absorption,which is more suitable for the study of this kind of materials,and the exciton binding energy E_b=20.65 me V is calculated.,optical band gap E_g=2.33 e V.Next,we measured the steady state luminescence spectrum of(PEA)₂PbI₄ single crystal,and defined the distinguishable surface state luminescence peak(peak at 528 nm)and bulk state luminescence peak(peak at 547 nm),indicating the bulk phase The crystal lattice is periodically destroyed on the crystal surface,and the surface state luminescence comes from the discontinuity caused by the reorganization of the crystal surface,and the steady-state luminescence spectra with different bulk/surface luminescence ratios representing the crystallinity are obtained.In the transient fluorescence spectrum test of(PEA)₂PbI₄ single crystal,we performed experimental multiple fitting of its fluorescence lifetime decay.By comparing the goodness of fit and standard deviation,we selected a perfectly suitable triple decay function fitting,the triple life component is obtained.By characterizing the fluorescence lifetime of(PEA)₂PbI₄ single crystals samples under different detection wavelengths and excitation light intensities,the fluorescence lifetime of the crystal is summarized by the influence of photon reabsorption and carrier diffusion,and the crystal's high crystallinity and suitable work are summarized.The condition is the basis for obtaining excellent optoelectronic properties,which is conducive to the application of high-performance optoelectronic devices.