Preparation And Optical Properties Of Novel Organic-inorganic Metal Halides

Organic-inorganic metal halides are polyhedral structures formed by coordination of large organic equilibrium cations and inorganic ions through self-assembly,and their structures have obvious perovskite and perovskite-like characteristics.In recent years,they have received more research interest,mainly because most of them belong to semiconductors and have important properties such as photoluminescence,which provides the possibility to explore new luminescent materials.The fusion of organic and inorganic components greatly enriches the structure of organic-inorganic metal halides and makes it possible to integrate the properties of the two components into a single compound,thus enabling unique optical properties.In addition,adjustable multicolor luminescence can be realized by doping new components into the structure.In this thesis,three metal halide crystal materials have been designed and prepared,including organic-inorganic hybrid and all-inorganic doping.After a detailed study of the crystal structure,it is found that they show unique photoluminescence properties.The main contents are listed as follows:（1）A 0D zirconium（Zr）based organic-inorganic metal halide（（CH₃）₄N）₂ZrCl₆single crystal was designed and synthesized.The hexagonal inorganic octahedron[ZrCl₆]^2-was evenly separated by large organic equilibrium cations[（CH₃）₄N]⁺to form the 0D structure at the molecular level.Its unique crystal structure made it excitation-dependent emission at ambient temperature and pressure.With the change of excitation wavelength,the emission color can be flexibly adjusted from blue to green to yellow to red.The optical characterization showed that the excitation wavelength dependence was caused by various emission mechanisms.This work is the first report on Zr-based organic-inorganic metal halides and extends the scope of color tunability of 0D materials under natural conditions.（2）A 1D manganese（Mn）based organic-inorganic halide C₅H₅NOMnCl₂·H₂O was designed and synthesized.Among them,O atoms in the organic equilibrium cations and water molecules were coordinated with Mn atoms to form a variant octahedron[MnCl₃O₃].Moreover,the edge-sharing 1D chain structure was formed by alternately sharing two O/Cl atoms.Its peculiar crystal structure allowed it to emit bright red photoluminescence under ultraviolet lamps.After the photoluminescence mechanism was verified,it was applied to the LED chip excited by blue light.The light was successfully lit up and the correlated color temperature was 1857 K.This work extends the scope of red light emission material in organic-inorganic metal halides.（3）A 2D cadmium（Cd）based co-doped all inorganic metal halide perovskite Cs₃Cd₂Cl₇:Sb³⁺:Mn²⁺single crystal was designed and synthesized.After the successful introduction of a small amount of Mn²⁺and Sb³⁺,it produces strong orange photoluminescence.When the light source is removed,it has a long afterglow for 10 s.At the same time,Mn²⁺and Sb³⁺single-doped single crystals were synthesized respectively to analyze the origin of the long afterglow phenomenon.All the doped single crystals show the flake characteristic morphology of pristine Cs₃Cd₂Cl₇.The optical characterization showed that the red afterglow originates from the synergistic interaction between Mn²⁺and Sb³⁺.This provides a successful example for design and synthesis of a new type of all-inorganic material with long afterglow.