| The physical properties of phase change materials can switch between two or more states,and have been widely used in data storage,optoelectronic devices,signal processing and other fields.As one of the best candidates for this type of material,the organic-inorganic hybrid material has attracted great interest from researchers due to its environmental friendliness,easy processing,and flexible structure.In this thesis,organic amine cations and Sb（III）/Cd（II）halogenated coordination anions were assembled,and four examples of ferroelectric,dielectric,and semiconducting multifunctional organic-inorganic hybrid materials were successfully synthesized.And the structure and related properties of the compound were studied.The main contents of this paper are as follows:1.A new organic-inorganic hybrid antimony bromide semiconductor compound[C6H13N3Sb Br5]（1）was successfully prepared.The corners in the structure of compound 1 share the antimony bromide octahedron to form a one-dimensional zigzag structure.The changes of symmetry plane and center of symmetry in the low-temperature structure and the synergistic effect of hydrogen bonds,compound 1exhibits a reversible phase transition around 230 K,with a significant Second Harmonic Generation（SHG）signal response and a narrow band gap of 2.52 e V.As we expected,ferroelectric materials with reversible phase change will provide a new way for the study of nonlinear optics and band gap.2.Using the chiral molecule（S）-3-hydroxypyrrolidine,combined with metal halides,two new molecular halides with reversible structural phase transition and multifunctional properties were designed and constructed.[C4H10NO]2Sb Cl5（2）and[C4H10NO]2Cd2Cl6（3）,through the analysis and measurement of single crystal structure,dielectric,Differential Scanning Calorimetry,Circular Dichroism,etc.,confirmed the occurrence of the reversible phase transition behavior of compounds 2and 3,deeply explored its phase transition mechanism,and studied the influence of structure on physical properties.Their dielectric and SHG response conversion indicate that compounds 2 and 3 may be an excellent candidate for potential convertible optoelectronic materials,which will also help to explore new multifunctional materials.3.Through simple H/F substitution,an organic-inorganic hybrid perovskite compound[C6H18F6N3Sb Br6]（4）with good reversible phase transition and semiconductor properties was synthesized.By introducing fluorine atoms to ethylamine,the symmetry of the structure is reduced,and the phase change is generated.The results show that compound 4 has three obvious dielectric anomalies near 175.9 K,205.9 K,and 257.5 K,respectively.Density functional theory calculations show that compound4 has a narrower band gap of 2.90 e V,and reveals the inorganic[Sb Br6]3-octahedral frame is the main contribution of its band gap.This work highlights that the substitution of hydrogen atoms by halogen has an important influence on its structural phase change mechanism and physical properties,and provides an effective strategy for the synthesis of new organic-inorganic hybrid perovskite-type phase change materials. |
