Preparation Of Two-dimensional Organic-inorganic Hybrid Perovskites Based On Organic Ligand Regulation And Research It's Photoelectric Properties

At present,perovskite-based materials are widely used in optoelectronic devices such as solar cells,light emitting diodes,and photodetectors.Compared with other optoelectronic materials,the preparation process of perovskite is simple and the cost is low.In terms of optoelectronic performance,perovskite are high photoelectric conversion efficiency,large carrier diffusion length,and low defect density.The two-dimensional perovskite is more easily adjusted photoelectric properties and better stability in the air.The first chapter summarizes the research status,preparation methods,and optoelectronic applications of two-dimensional organic-inorganic hybrid perovskite materials,and then introduce the research background and significance of this article.In the second chapter,we introduce the experimental materials for preparing two-dimensional organic-inorganic hybrid perovskites.And we introduce the working principle and operating parameters of characterization equipment.In the third chapter,we bring the different organic chain length into perovskite and studied photoelectric properties.Two-dimensional(2D)organic-inorganic hybrid perovskites(OIHPs)have recently drawn great interest due to their easy synthesis and excellent photoelectric properties.With tunable bandgaps,2D OIHPs have been widely investigated for use in solar cells,photodetectors and optoelectronic sensors.In this work,we synthesized three types of 2D perovskites with different organic chains,(CH₃(CH₂)₃NH₃)₂Pb I₄(C4,(BA)₂Pb I₄),(CH₃(CH₂)₅NH₃)₂Pb I₄(C6,(HA)₂Pb I₄)and(CH₃(CH₂)₇NH₃)₂Pb I₄(C8,(OA)₂Pb I₄),and investigated their photoelectric properties.With increasing organic chain length,the inter-layer spacing,bandgaps and stability in air increased correspondingly.In addition,tunable optoelectronic properties were achieved when these three perovskites with different organic chain cations were employed to fabricate photodetectors.The results provide an effective method for synthesizing various OIHPs via tuning different organic cations and are helpful to broaden the applications of OIHPs in photoelectric devices.In the fourth chapter,we bring fluorescent organic groups into two-dimensional organic-inorganic hybrid perovskite.Room-temperature phosphorescence(RTP)is a photophysical process that generates triplet state excitons in organic molecules,which then radiate to the ground state.RTP materials have been widely studied in various optoelectronic applications,such as organic light-emitting diodes(OLEDs),anticounterfeiting,bioimaging and so on.Although RTP exhibits unique advantages,such as slow exciton decay rates and sensitive biological sensing,it is difficult to detect RTP in 2D OIHPs.In this work,naphthalenemethyl ammonium(NEA),a typical organic fluorophore molecule with a triplet state energy level lower than that of the inorganic layer[Pb Br₄]^2–,was doped into 2D(C₆H₅C₂H₄NH₃)₂Pb Br₄((PEA)₂Pb Br₄)to achieve energy transfer from the inorganic component to the organic triplet state and then to generate RTP.With the doped NEA,the phosphorescence lifetime can reach 2.95 ms for the(PEA)_0.8(NEA)_1.2Pb Br₄ material with an emission peak at 473 nm,and the photoluminescence spectrum covered the entire visible spectrum when excited at 365 nm ultraviolet light.These results provide an effective strategy to tune the RTP in perovskite materials via varying the ratio of organic fluorophore molecules,which is also important for the applications of OIHPs in the optoelectronic area.In the fifth chapter,we take conclusion and outlook of the research work.