Charge transport in single molecules
Description
Studying charge transport through single molecules is of great importance for unravelling charge transport mechanisms, investigating fundamentals of chemistry, and developing functional building blocks in molecular electronics.
First, a study of the thermoelectric effect in single DNA molecules is reported. By varying the molecular length and sequence, the charge transport in DNA was tuned to either a hopping- or tunneling-dominated regimes. In the hopping regime, the thermoelectric effect is small and insensitive to the molecular length. Meanwhile, in the tunneling regime, the thermoelectric effect is large and sensitive to the length. These findings indicate that by varying its sequence and length, the thermoelectric effect in DNA can be controlled. The experimental results are then described in terms of hopping and tunneling charge transport models.
Then, I showed that the electron transfer reaction of a single ferrocene molecule can be controlled with a mechanical force. I monitor the redox state of the molecule from its characteristic conductance, detect the switching events of the molecule from reduced to oxidized states with the force, and determine a negative shift of ~34 mV in the redox potential under force. The theoretical modeling is in good agreement with the observations, and reveals the role of the coupling between the electronic states and structure of the molecule.
Finally, conclusions and perspectives were discussed to point out the implications of the above works and future studies that can be performed based on the findings.
First, a study of the thermoelectric effect in single DNA molecules is reported. By varying the molecular length and sequence, the charge transport in DNA was tuned to either a hopping- or tunneling-dominated regimes. In the hopping regime, the thermoelectric effect is small and insensitive to the molecular length. Meanwhile, in the tunneling regime, the thermoelectric effect is large and sensitive to the length. These findings indicate that by varying its sequence and length, the thermoelectric effect in DNA can be controlled. The experimental results are then described in terms of hopping and tunneling charge transport models.
Then, I showed that the electron transfer reaction of a single ferrocene molecule can be controlled with a mechanical force. I monitor the redox state of the molecule from its characteristic conductance, detect the switching events of the molecule from reduced to oxidized states with the force, and determine a negative shift of ~34 mV in the redox potential under force. The theoretical modeling is in good agreement with the observations, and reveals the role of the coupling between the electronic states and structure of the molecule.
Finally, conclusions and perspectives were discussed to point out the implications of the above works and future studies that can be performed based on the findings.
Date Created
The date the item was original created (prior to any relationship with the ASU Digital Repositories.)
2017
Agent
- Author (aut): Li, Yueqi, Ph.D
- Thesis advisor (ths): Tao, Nongjian
- Committee member: Buttry, Daniel
- Committee member: Mujica, Vladimiro
- Publisher (pbl): Arizona State University