Related Experiment Video
Updated: Mar 8, 2026
04:14
Facile Synthesis of Colloidal Lead Halide Perovskite Nanoplatelets via Ligand-Assisted Reprecipitation
Published on: October 1, 2019
13.7K
Double Charged Surface Layers in Lead Halide Perovskite Crystals
Smritakshi P Sarmah, Victor M Burlakov1, Emre Yengel
1Mathematical Institute, University of Oxford , Woodstock Road, Oxford OX2 6GG, United Kingdom.
Nano Letters
|February 2, 2017
Summary
Defect chemistry in hybrid perovskites causes surface charge separation, altering optical properties. Understanding this ion migration is key to improving perovskite device performance.
Area of Science:
- Materials Science
- Solid-State Chemistry
- Device Physics
Background:
- Hybrid perovskite devices face challenges due to ion migration affecting surface properties.
- Understanding defect chemistry is crucial for advancing perovskite technology.
Purpose of the Study:
- To investigate the origins of surface effects in hybrid perovskite crystals.
- To elucidate the relationship between ion migration, charge separation, and optical properties.
Main Methods:
- Combined experimental and theoretical approaches.
- Analysis of surface layers in perovskite crystals.
- Investigation of halide and organic moiety influence.
Main Results:
- Demonstrated charge separation with positive vacancies and negative halide ions at the surface.
- Observed an electric field-induced increase in the optical band gap of surface layers.
- Found that band gap shifts depend on perovskite composition (halides and organic groups).
Conclusions:
- Surface effects in perovskites are peculiar and limit device applications.
- The study explains the origins of these surface effects.
- Findings enable development of surface passivation strategies for perovskite remediation.
Related Concept Videos
01:30The Electrical Double Layer
84
In the region where two bulk phases meet, an intricate electric charge distribution arises due to charge transfer, ion adsorption, molecular orientation, and charge distortion. This complex distribution is commonly referred to as the electrical double layer.When a solid electrode interfaces with ions in an electrolyte solution, the speed of electron transfer dictates the rates of oxidation and reduction. The electrode acquires a charge through the escape of atoms into the solution as cations or...
84
01:26Imperfections in Crystal Structure: Stoichiometric Point Defects
29
Schottky defects arise when some lattice points in a crystal, such as those in NaCl, remain unoccupied, creating lattice vacancies without disturbing the overall electrical neutrality of the crystal. This defect is common in ionic crystals where the positive and negative ions are similar in size, as seen in sodium chloride and cesium chloride. The presence of Schottky defects enables the crystal to conduct electricity to a small extent through an ionic mechanism. Electric fields cause nearby...
29
02:42Ionic Crystal Structures
19.4K
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...
19.4K
02:46Crystal Field Theory - Tetrahedral and Square Planar Complexes
49.3K
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,...
49.3K
01:29Potential Due to a Polarized Object
865
A neutral atom consists of a positively charged nucleus surrounded by a negatively charged electron cloud. When placed in an external electric field, the external electric force pulls the electrons and nucleus apart, opposite to the intrinsic attraction between the nucleus and the electrons. The opposing forces balance each other with a slight shift between the center of masses of the nucleus and the electron cloud, resulting in a polarized atom. On the other hand, a few molecules, like water,...
865
02:37Metallic Solids
21.2K
Metallic solids such as crystals of copper, aluminum, and iron are formed by metal atoms. The structure of metallic crystals is often described as a uniform distribution of atomic nuclei within a “sea” of delocalized electrons. The atoms within such a metallic solid are held together by a unique force known as metallic bonding that gives rise to many useful and varied bulk properties.
All metallic solids exhibit high thermal and electrical conductivity, metallic luster, and malleability....
All metallic solids exhibit high thermal and electrical conductivity, metallic luster, and malleability....
21.2K