分子ワイヤのホッピング伝導は,大きな重原子運動同位体効果を示す

Quyen Van Nguyen¹, C Daniel Frisbie¹

¹Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, Minnesota 55455, United States.

Journal of the American Chemical Society

|February 15, 2021

まとめ

長い有機線で電荷を運ぶ大きな運動同位体効果 (KIE) を発見しましたこの発見は,分子電子学の電子運動のための新しいメカニズムを示唆しています.

科学分野:

分子電子
量子輸送現象
有機半導体物理学

背景:

分子内部での電荷輸送は分子電子学にとって極めて重要です
運動同位体効果 (KIE) は反応機構と輸送経路の敏感な探査物である.
π結合分子における電荷輸送を理解することは,新しい電子機器の開発の鍵です.

研究の目的:

オリゴフェニレニミン (OPI) 分子の分子内電荷輸送のメカニズムを調査する.
OPI分子ワイヤの伝導性に対する運動同位体効果 (KIE) を定量化する.
同位体置換が電荷輸送特性を調節する役割を明らかにする.

主な方法:

金の電極に接続されたOPI分子ワイヤの製造.
同位体で標識されたOPI分子 (CとNを使用) の合成.
同位体ラベルを付けているとしていないOPIワイヤの導電性と温度に依存する導電性の測定

主要な成果:

長 OPI ワイヤ (> 4 nm) に対して,大きな KIE (標識された原子あたり ~ 2. 7) が観察されました.
短いOPIワイヤ (<4 nm) では有意なKIEは観察されず,直接トンネリングメカニズムを示しています.
長,NラベルのOPIワイヤの伝導性は,温度によって活性化された行動を示した.

結論:

長いOPIワイヤの大きなKIEは,熱的に支援された,バリアを通過するポラロントンネルメカニズムを示唆しています.
短線でのKIEの欠如は,直接トンネリングモデルをサポートします.
大導電性KIEの観測は,分子システムにおける電荷輸送メカニズムを理解するための強力なツールを提供します.

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