在pi-结合材料中解离光学和电位计带间隙
Kimihiro Susumu1, Michael J Therien
1Department of Chemistry, University of Pennsylvania Philadelphia, Pennsylvania 19104-6323, USA.
Journal of the American Chemical Society
|July 18, 2002
概括
研究人员用乙烯桥合成了新的合氨酸寡合体. 这些分子尽管具有扩展的电子结构,但表现出稳定的氧化还原潜力,从而能够精确控制它们的光电子特性.
科学领域:
- 材料科学 材料科学 材料科学
- 超分子化学 超分子化学
- 有机电子 有机电子
背景情况:
- 结合式氨酸寡合体因其独特的电子和光学特性而引起人们的兴趣.
- 以前的研究集中在氨酸寡合物与简单的烯替代物.
- 在扩展联系统中调整氧化还原潜力仍然是一个挑战.
研究的目的:
- 合成和表征两类乙烯桥接甲 (porphyrinatozinc) 的二氧化物.
- 为了研究电子丰富和电子贫乏单位交替对电子结构的影响.
- 为了确定高度非局部化的兴奋状态是否可以与稳定的氧化还原潜力共存.
主要方法:
- 用不同的替代剂合成新型氨酸寡合物.
- 光学光谱学用于研究电子过渡.
- 电位测量研究以确定氧化还原潜力.
- 电子结构计算用于理论分析.
主要成果:
- 成功合成了具有乙烯链接的可溶性氨酸寡合物.
- 准备了具有交替电子丰富和电子贫穷单位的寡合体.
- 这些结合系统显示出高度脱局的单点兴奋状态 (S1).
- 观察到的单电子氧化和还原潜力与单质前体相比是不变的.
结论:
- 有可能设计具有量身定制的光电子特性的合寡合结构.
- 在扩展系统中观察到的氧化还原稳定性为新材料设计开辟了道路.
- 这些发现有助于理解基于氨酸的材料中的结构性质关系.
相关概念视频
Semiconductors
There is variation in the electrical conductivity of materials - metals, semiconductors, and insulators that are showcased with the help of the energy band diagrams.
Metals such as copper (Cu), zinc (Zn), or lead (Pb) have low resistivity and feature conduction bands that are either not fully occupied or overlap with the valence band, making a bandgap non-existent. This allows electrons in the highest energy levels of the valence band to easily transition to the conduction band upon gaining...
Metals such as copper (Cu), zinc (Zn), or lead (Pb) have low resistivity and feature conduction bands that are either not fully occupied or overlap with the valence band, making a bandgap non-existent. This allows electrons in the highest energy levels of the valence band to easily transition to the conduction band upon gaining...
Carrier Generation and Recombination
Carrier generation is the process by which electron-hole pairs (EHPs) are created within the semiconductor. In direct-bandgap semiconductors, such as gallium arsenide (GaAs), this occurs efficiently when energy absorption prompts valence electrons to leap into the conduction band, leaving behind holes.
This process is given by the generation rate G and is efficient due to the conservation of momentum between the valence band maximum and conduction band minimum.
Indirect generation involves an...
This process is given by the generation rate G and is efficient due to the conservation of momentum between the valence band maximum and conduction band minimum.
Indirect generation involves an...
P-N junction
A p-n junction is formed when p-type and n-type semiconductor materials are joined together. At the interface of the p-n junction, holes from the p-side and electrons from the n-side begin to diffuse into the opposite sides due to the concentration gradient. This diffusion of carriers leads to a region around the junction where there are no free charge carriers, known as the depletion region. The charge density within the depletion region for the n-side and p-side can be described by the...
Biasing of P-N Junction
The operation of a p-n junction diode involves various biasing conditions, including forward bias, reverse bias, and equilibrium.
In equilibrium, no external voltage is applied across the p-n junction. The depletion region is formed at the junction interface due to the diffusion of carriers, which leaves behind charged dopants, acceptors on the p-side, and donors on the n-side. These immobile charges create an electric field that prevents further diffusion of carriers. The related energy band...
In equilibrium, no external voltage is applied across the p-n junction. The depletion region is formed at the junction interface due to the diffusion of carriers, which leaves behind charged dopants, acceptors on the p-side, and donors on the n-side. These immobile charges create an electric field that prevents further diffusion of carriers. The related energy band...
Metal-Semiconductor Junctions
The contact of metal and semiconductor can lead to the formation of a junction with either Schottky or Ohmic behavior.
Schottky Barriers
Schottky barriers arise when a metal with a work function (Φm) contacts a semiconductor with a different work function (Φs). Initially, electrons transfer until the Fermi levels of the metal and semiconductor align at equilibrium. For instance, if Φm > Φs, the semiconductor Fermi level is higher than the metal's before contact. The semiconductor's...
Schottky Barriers
Schottky barriers arise when a metal with a work function (Φm) contacts a semiconductor with a different work function (Φs). Initially, electrons transfer until the Fermi levels of the metal and semiconductor align at equilibrium. For instance, if Φm > Φs, the semiconductor Fermi level is higher than the metal's before contact. The semiconductor's...
Biasing of Metal-Semiconductor Junctions
Biasing metal-semiconductor junctions involves applying a voltage across the junction. Specifically, the metal is connected to a voltage source, while the semiconductor is grounded. This technique is essential for controlling the direction and magnitude of current flow in electronic devices, including diodes, transistors, and photovoltaic cells.
In Schottky junctions, where the semiconductor is n-type, applying a positive voltage to the metal relative to the semiconductor reduces its Fermi...
In Schottky junctions, where the semiconductor is n-type, applying a positive voltage to the metal relative to the semiconductor reduces its Fermi...


