在二维化佩洛夫斯基特中使用大酸的负压工程导致格子软化
Xiaotong Li1, Yongping Fu1, Laurent Pedesseau2
1Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States.
Journal of the American Chemical Society
|June 4, 2020
概括
在二维矿中较大的A位离子扩大了戈德施密特容忍因子,改变了Pb-I键和光学带隙. 这种调整影响光电子特性,为半导体研究提供了新的途径.
科学领域:
- 材料科学
- 固态化学
- 光电子产品
背景情况:
- 有机-无机混合化是可调节的半导体.
- 在三维矿 (AMX3) 中,几何约束限制了选择.
- 2D矿在A位选择中提供了灵活性,使得结构与属性关系的研究成为可能.
研究的目的:
- 调查二维矿中A位点离子大小的变化 ((BA) 2 (A) Pb2I7) 如何影响结构和光电子特性.
- 在二维矿系统中探索几何约束的放松.
- 了解A位点离子在调节矿体积和光电子行为的作用.
主要方法:
- 合成单晶 (BA) 2 (A) Pb2I7 矿,其中A=甲基 (MA),甲基 (FA),二甲基 (DMA) 或 (GA).
- 单晶X射线衍射以确定晶体结构和空间组 (Cmcm,Ccmb).
- 光学光谱,密度函数理论 (DFT) 计算和拉曼光谱分析结构和电子性质.
- 暂时吸收显微镜用于研究光发光衰变机制.
主要成果:
- 较大的A位点离子 (MA,FA,GA,DMA) 被纳入二维矿结构.
- 阴离子大小的增加导致了Pb-I键的延长和矿的扩张 ("负压").
- 通过减少轨道重叠,Pb-I键的延长增加了光学带隙;Pb-I-Pb倾斜起到了较小的作用.
- 在较大的阴离子中观察到晶格软化和光发光强度/寿命降低,这表明非辐射衰变增加.
结论:
- 在二维矿中,通过结合较大的A位点离子,可以放松戈德施密特容忍因子的限制.
- A位点离子大小是调整二维矿结构和光电子特性的一个关键参数.
- 这些发现可以进一步控制光电子应用的二维矿性能.
更多相关视频
08:12Low Pressure Vapor-assisted Solution Process for Tunable Band Gap Pinhole-free Methylammonium Lead Halide Perovskite Films
Published on: September 8, 2017
9.9K
04:14Facile Synthesis of Colloidal Lead Halide Perovskite Nanoplatelets via Ligand-Assisted Reprecipitation
Published on: October 1, 2019
13.4K
相关概念视频
02:54Trends in Lattice Energy: Ion Size and Charge
26.3K
An ionic compound is stable because of the electrostatic attraction between its positive and negative ions. The lattice energy of a compound is a measure of the strength of this attraction. The lattice energy (ΔHlattice) of an ionic compound is defined as the energy required to separate one mole of the solid into its component gaseous ions. For the ionic solid sodium chloride, the lattice energy is the enthalpy change of the process:
26.3K
02:42Ionic Crystal Structures
16.6K
Ionic crystals consist of two or more different kinds of ions that usually have different sizes. The packing of these ions into a crystal structure is more complex than the packing of metal atoms that are the same size.
Most monatomic ions behave as charged spheres, and their attraction for ions of opposite charge is the same in every direction. Consequently, stable structures for ionic compounds result (1) when ions of one charge are surrounded by as many ions as possible of the opposite...
Most monatomic ions behave as charged spheres, and their attraction for ions of opposite charge is the same in every direction. Consequently, stable structures for ionic compounds result (1) when ions of one charge are surrounded by as many ions as possible of the opposite...
16.6K
02:46Crystal Field Theory - Tetrahedral and Square Planar Complexes
47.4K
Tetrahedral Complexes
Crystal field theory (CFT) is applicable to molecules in geometries other than octahedral. In octahedral complexes, the lobes of the dx2−y2 and dz2 orbitals point directly at the ligands. For tetrahedral complexes, the d orbitals remain in place, but with only four ligands located between the axes. None of the orbitals points directly at the tetrahedral ligands. However, the dx2−y2 and dz2 orbitals (along the Cartesian axes) overlap with the ligands less than the dxy,...
Crystal field theory (CFT) is applicable to molecules in geometries other than octahedral. In octahedral complexes, the lobes of the dx2−y2 and dz2 orbitals point directly at the ligands. For tetrahedral complexes, the d orbitals remain in place, but with only four ligands located between the axes. None of the orbitals points directly at the tetrahedral ligands. However, the dx2−y2 and dz2 orbitals (along the Cartesian axes) overlap with the ligands less than the dxy,...
47.4K
02:58Crystal Field Theory - Octahedral Complexes
30.1K
Crystal Field Theory
To explain the observed behavior of transition metal complexes (such as colors), a model involving electrostatic interactions between the electrons from the ligands and the electrons in the unhybridized d orbitals of the central metal atom has been developed. This electrostatic model is crystal field theory (CFT). It helps to understand, interpret, and predict the colors, magnetic behavior, and some structures of coordination compounds of transition metals.
CFT focuses on...
To explain the observed behavior of transition metal complexes (such as colors), a model involving electrostatic interactions between the electrons from the ligands and the electrons in the unhybridized d orbitals of the central metal atom has been developed. This electrostatic model is crystal field theory (CFT). It helps to understand, interpret, and predict the colors, magnetic behavior, and some structures of coordination compounds of transition metals.
CFT focuses on...
30.1K
02:44The Born-Haber Cycle
24.8K
Lattice Energy
24.8K
02:48Ionic Bonding and Electron Transfer
48.2K
Ions are atoms or molecules bearing an electrical charge. A cation (a positive ion) forms when a neutral atom loses one or more electrons from its valence shell, and an anion (a negative ion) forms when a neutral atom gains one or more electrons in its valence shell. Compounds composed of ions are called ionic compounds (or salts), and their constituent ions are held together by ionic bonds: electrostatic forces of attraction between oppositely charged cations and anions.
48.2K