光スイッチ可能なダイメチルジヒドロピレン型単分子結合で電荷輸送
Diego Roldan1, Veerabhadrarao Kaliginedi, Saioa Cobo
1Département de Chimie Moléculaire, UMR CNRS-5250, Institut de Chimie Moléculaire de Grenoble, FR CNRS-2607, Université Joseph Fourier Grenoble I, BP 53, 38041 Grenoble Cedex 9, France.
Journal of the American Chemical Society
|April 12, 2013
まとめ
研究者は,電子機器のための光スイッチ可能な分子を研究した. ディメチルジヒドロピレン (DHP) デリバティブは,電気伝導性の大きく,可逆的な変化を示し,分子スイッチングアプリケーションで高いオン/オフ比率を達成しました.
科学分野:
- 分子電子 (モレキュラー・エレクトロニクス)
- 超分子化学 超分子化学
- ナノテクノロジー ナノテクノロジー
背景:
- フォトスイッチ可能な分子は,調節可能な電子特性を提供します.
- 単一分子結合は,ナノスケールの電子機器にとって極めて重要です.
研究 の 目的:
- フォトスイッチ可能なダイメチルジヒドロピレン (DHP) デリバティブの伝導性特性を調査する.
- 分子構造の変化と単一分子結合の伝導率の変動を相関させる.
主な方法:
- 機械的に制御可能なブレイクジャンクション (MCBJ) テクニックを使用しました.
- DHP誘導体による単分子結合の製造と測定.
主要な成果:
- 単一のDHP分子における可逆導電性スイッチングが実証されています.
- DHPのイソメリゼーションで伝導率の大幅な低下 (>10^4 ON/OFF比) が観察されました.
- 導電性のスイッチングの優れた可逆性が確認されました.
結論:
- フォトスイッチ可能なDHP誘導体は,分子電子アプリケーションにおいて有望である.
- アイソメリゼーションによって引き起こされる構造の変化は,単一分子伝導性を効果的に調節します.
- 高いオン/オフ比率と可逆性は,実用的な分子スイッチの鍵です.
関連する概念動画
01:11P-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...
01:26Photochemical Electrocyclic Reactions: Stereochemistry
The absorption of UV–visible light by conjugated systems causes the promotion of an electron from the ground state to the excited state. Consequently, photochemical electrocyclic reactions proceed via the excited-state HOMO rather than the ground-state HOMO. Since the ground- and excited-state HOMOs have different symmetries, the stereochemical outcome of electrocyclic reactions depends on the mode of activation; i.e., thermal or photochemical.
Selection Rules: Photochemical Activation
Selection Rules: Photochemical Activation
01:27Photosystem I
Although structurally similar to photosystem II (PSII), photosystem I (PSI) is has a different electron supplier and electron acceptor.
Both these photosystems work in concert. An excited electron from PSII is relayed to PSI via an electron transport chain in the thylakoid membrane of the chloroplast, which is comprised of the carrier molecule plastoquinone, the dual-protein cytochrome complex, and plastocyanin. As electrons move between PSII and PSI, they lose energy and must be re-energized...
Both these photosystems work in concert. An excited electron from PSII is relayed to PSI via an electron transport chain in the thylakoid membrane of the chloroplast, which is comprised of the carrier molecule plastoquinone, the dual-protein cytochrome complex, and plastocyanin. As electrons move between PSII and PSI, they lose energy and must be re-energized...
01:26Thermal and Photochemical Electrocyclic Reactions: Overview
Electrocyclic reactions are reversible reactions. They involve an intramolecular cyclization or ring-opening of a conjugated polyene. Shown below are two examples of electrocyclic reactions. In the first reaction, the formation of the cyclic product is favored. In contrast, in the second reaction, ring-opening is favored due to the high ring strain associated with cyclobutene formation.
01:24Metal-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...