The Synthesis Of Novel Organic-Inorganic Hybrid Halide Perovskite And Study On Circularly Polarized Photodetectors

Organic inorganic hybrid halide perovskite is a new type of material that has shown great potential in applications such as solar cells,light-emitting diodes,and photodetectors.The organic-inorganic hybrid halide perovskite has both the solvable processing characteristics of organic materials and the excellent photoelectric properties of inorganic materials.It has excellent photophysical properties such as high absorption coefficient,long exciton diffusion distance,and low exciton binding energy.Among them,two-dimensional organic-inorganic hybrid halide perovskite has gradually become a research hotspot in the field of perovskite due to its excellent photostability,thermal stability,and rich structural adjustability.The two-dimensional organic-inorganic hybrid halide perovskite structure integrates many advantages of both organic and inorganic materials,such as the structural diversity and functionality of organic materials,as well as the magnetism and high carrier mobility of inorganic materials,making it an ideal platform for designing and synthesizing new functional materials.However,research on magnetic materials based on perovskite structures and their applications in the field of nonlinear optics is still in its infancy.This paper aims to design and synthesize new perovskite ferromagnetic materials,prepare a series of novel two-dimensional organic-inorganic hybrid perovskite materials,explore their magnetic and nonlinear optical properties,and explore their applications in polarized light detectors.By regulating the types of organic ammonium ions,metal ions,and halogens,the ferromagnetic,thermochromic,chiral,and second harmonic properties of these materials were investigated.Furthermore,a polarized light detector was prepared and good device performance was achieved.This paper provides a new strategy for creating new functional materials,especially new ferromagnets,using perovskite structures,and provides a reference for further developing magnetic materials for spin devices.The main content of the paper is as follows:Chapter 1:Firstly,introduce the research background and classification of organic-inorganic hybrid halide perovskite.The basic phenomenon of second harmonic is explained,and its nonlinear optical coupled wave equation is derived.Subsequently,the dependence of second harmonic intensity on various conditions is obtained under the condition of small signal approximation.Summarize the research content on the ferromagnetic and second harmonic properties of organic-inorganic hybrid halide perovskites.Finally,summarize the research progress in polarized light detectors based on organic-inorganic hybrid lead based and non lead halide perovskites.On this basis,the topic selection ideas and research significance of this paper have been formed.Chapter 2:Twelve new two-dimensional hybrid perovskite（Cn）₂Cu X₄ were prepared,n=2,3,4,5,6,7;X=Cl,Br),studied the regulation of organic molecules on perovskite magnetism,and found that the in-plane magnetism changed from ferromagnetism to paramagnetism with the increase of carbon chain length,while the in-plane magnetism remained ferromagnetic.We selected ethylamine,propylamine,butylamine,pentamine,hexylamine,and heptadine to synthesize organic-inorganic hybrid copper based chloride perovskite and organic-inorganic hybrid copper based bromination,respectively.Perovskite achieves continuous and adjustable interlayer distance by changing the length of organic carbon chains.Magnetic testing shows that its out of plane magnetism changes from ferromagnetism to paramagnetism as the carbon chain distance increases.Through the study of powder XRD and Raman spectroscopy,we found that as the interlayer distance increases,the Raman peak position gradually shifts red with the increase of interlayer distance;And the internal and external magnetism maintains ferromagnetism as the distance between layers changes;The paramagnetic electron resonance test shows that when the halogen atom is changed from chlorine to bromine,the ESR signal peak changes from 2.02 to 2.13.In addition,the（Cn）₂Cu X₄ series of compounds exhibit reversible thermochromic behavior.The variation of interlayer distance between two-dimensional organic-inorganic hybrid copper based calcium titanium minerals can regulate the ferromagnetic and paramagnetic resonance properties of materials.Chapter 3:A series of new chiral zero dimensional hybrid copper halides were designed and synthesized.The R and S enantiomer all exhibit symmetric circular dichroism and strong second harmonic properties.In this work,six chiral zero dimensional organic-inorganic hybrid copper halides were synthesized based on chiral organic amines（R-,S-MBA）and chiral organic amines（R-,S-2MBA;R-,S-3MBA）substituted by F atoms,namely（R-,S-MBA）₂Cu Cl₄,（R-,S-2MBA）₂Cu Cl₄,and（R-,S-3MBA）₂Cu Cl₄.Based on the six compounds mentioned above,we have synthesized micro/nano crystals,bulk single crystals,and in situ grown single crystal microsheets on silicon wafers.The circular dichroic spectrum test shows that（R-,S-2MBA）₂Cu Cl₄exhibits an enhanced circular dichroic spectrum signal compared to（R-,S-3MBA）₂Cu Cl₄,indicating that ortho substituted chiral amines enhance the circular dichroic spectrum signal of metal halides compared to meta substituted chiral amines.In the circular dichroism spectrum,it can be seen that after the introduction of F atoms,there is a circular dichroism signal inversion at 610nm for（R-,S-3MBA）₂Cu Cl₄,while the circular dichroism signal inversion at 610nm for（R-,S-2MBA）₂Cu Cl₄ disappears.We prepared single crystal micrometer chips with adjustable thickness and tested the intensity dependent second harmonic effect.These six organic inorganic hybrid copper based halides have second harmonic characteristics in their single crystal micro chips.In addition,through second harmonic imaging,we found the presence of boundary enhancement effects,which has potential application prospects in the field of second harmonic imaging.The tunable circular dichroic signal and second harmonic properties provide a material foundation for the application of metal halides in nonlinear optics..Chapter 4:A polarized light detector based on chiral organic-inorganic hybrid lead based and copper based halide perovskite was prepared,exhibiting fast light responsiveness.Polarized light detectors based on（R-MPEA）₂Pb I₄ and（R-MPEA）₂MAPb₂I₇ thin films were prepared,achieving detection of 532 nm polarized light and analyzing the effect of light intensity on responsiveness.