Related Experiment Video
Updated: Feb 13, 2026
07:05
In vitro Cannabis Exposures of Lung Epithelial Cells at the Air-Liquid Interface
Published on: June 20, 2025
948
Local Electronic Structure Changes in Polycrystalline CdTe with CdCl2 Treatment and Air Exposure
Morgann Berg1, Jason M Kephart2, Amit Munshi2
1Sandia National Laboratories , Albuquerque , New Mexico 87185 , United States.
ACS Applied Materials & Interfaces
|March 13, 2018
Summary
Cadmium chloride (CdCl2) treatment and oxygen exposure can improve cadmium telluride (CdTe) solar cells. Spectroscopic photoemission electron microscopy revealed how these treatments alter electronic structures at grain boundaries, enhancing photovoltaic performance.
Area of Science:
- Materials Science
- Solid-State Physics
- Photovoltaics
Background:
- Postdeposition cadmium chloride (CdCl2) treatment is a standard method for enhancing polycrystalline cadmium telluride (CdTe) solar cell efficiency.
- The exact mechanisms by which CdCl2 treatment improves device performance, involving chemical, structural, and electronic modifications, remain incompletely understood.
- Understanding variations in electronic structure between grain interiors and grain boundaries (GBs) is crucial for optimizing CdTe photovoltaic devices.
Purpose of the Study:
- To spatially map the vacuum level and ionization energy of CdTe films using spectroscopic photoemission electron microscopy (SPEEM).
- To differentiate the effects of CdCl2 treatment and ambient oxygen exposure on the electronic structure of CdTe surfaces and grain boundaries.
- To quantify the electronic properties of space charge regions at GBs in CdTe films.
Main Methods:
- Spectroscopic photoemission electron microscopy (SPEEM) was employed to spatially resolve variations in electronic properties.
- In vacuo preparation and inert transfer techniques were used to maintain oxide-free CdTe surfaces.
- Analysis focused on mapping vacuum levels and ionization energies to identify differences between grains and GBs.
Main Results:
- Grain boundaries exhibited lower work function and downward band bending compared to grain interiors, specifically after air exposure of CdCl2-treated CdTe.
- Average depletion width at GBs was measured at 290 nm, with an average band bending magnitude of 70 meV.
- Calculated GB trap density was 10^11 cm^-2, and net carrier density was 10^15 cm^-3.
Conclusions:
- CdCl2 treatment and oxygen exposure independently influence the electronic structure of CdTe films.
- These treatments can be tuned to engineer the interface and bulk electronic properties of CdTe.
- Optimizing these parameters offers a pathway to enhance CdTe photovoltaic device performance.
Related Concept Videos
02:28Electronic Structure of Atoms
29.0K
An atom comprises protons and neutrons, which are contained inside the dense, central core called the nucleus, with electrons present around the nucleus. Taking into account the wave–particle duality of electrons and the uncertainty in position around the nucleus, quantum mechanics provides a more accurate model for the atomic structure. It describes atomic orbitals as the regions around the nucleus where electrons of discrete energy exist, characterized by four quantum...
29.0K
01:07Radicals: Electronic Structure and Geometry
5.1K
This lesson delves into the geometry of a radical, which is influenced by the electronic structure of the molecule. The principle is similar to that of a lone pair, where the unpaired electron influences the geometry at the radical center.
Accordingly, the structure of a trivalent radical lies between the geometries of carbocations and carbanions. An sp2-hybridized carbocation is trigonal planar, while an sp3-hybridized carbanion is trigonal pyramidal. Here, the difference in geometry is...
Accordingly, the structure of a trivalent radical lies between the geometries of carbocations and carbanions. An sp2-hybridized carbocation is trigonal planar, while an sp3-hybridized carbanion is trigonal pyramidal. Here, the difference in geometry is...
5.1K
01:30Local Anesthetics: Chemistry and Structure-Activity Relationship
6.8K
Local anesthetics (LAs) are drugs that induce a temporary loss of sensation in a limited body area, preventing pain. Cocaine was the first local anesthetic discovered in the late 19th century. Cocaine is a benzoic acid ester obtained from the leaves of coca shrubs and was often used for its psychotropic effects. Cocaine was first isolated in 1860 by Albert Niemann. Sigmund Freud studied the physiological actions of cocaine. Carl Koller later introduced it into clinical practice in 1884 as a...
6.8K
01:24Electron Carriers
92.1K
Electron carriers can be thought of as electron shuttles. These compounds can easily accept electrons (i.e., be reduced) or lose them (i.e., be oxidized). They play an essential role in energy production because cellular respiration is contingent on the flow of electrons.
Over the many stages of cellular respiration, glucose breaks down into carbon dioxide and water. Electron carriers pick up electrons lost by glucose in these reactions, temporarily storing and releasing them into the electron...
Over the many stages of cellular respiration, glucose breaks down into carbon dioxide and water. Electron carriers pick up electrons lost by glucose in these reactions, temporarily storing and releasing them into the electron...
92.1K
02:34Structural Isomerism
21.8K
Isomerism in Complexes
Isomers are different chemical species that have the same chemical formula. Structural isomerism of coordination compounds can be divided into two subcategories, the linkage isomers and coordination-sphere isomers.
Linkage isomers occur when the coordination compound contains a ligand that can bind to the transition metal center through two different atoms. For example, the CN− ligand can bind through the carbon atom or through the nitrogen atom. Similarly, SCN− can...
Isomers are different chemical species that have the same chemical formula. Structural isomerism of coordination compounds can be divided into two subcategories, the linkage isomers and coordination-sphere isomers.
Linkage isomers occur when the coordination compound contains a ligand that can bind to the transition metal center through two different atoms. For example, the CN− ligand can bind through the carbon atom or through the nitrogen atom. Similarly, SCN− can...
21.8K
03:07Electron Affinity
43.7K
The electron affinity (EA) is the energy change for adding an electron to a gaseous atom to form an anion (negative ion).
43.7K