Investigation Of Quantum Interference Regulation In Single-Molecule Charge Transport Based On Charge Injection And Light Induction

The quantum interference(QI)effect in the charge transport process of singlemolecules can significantly affect the charge transport properties in the molecular structure in a constructive or destructive manner.It is of great significance for the direct manipulation of the charge transfer in the molecular junction,and it has presented broad application prospects in the preparation of tunable high-performance molecular devices in the future.To develop the tuning method of QI is the cutting-edge research direction of single-molecule electronics.After decades of research,various methods of regulating QI such as mechanical regulating,electrochemical regulating and chemical regulating have been extensively studied.However,a universal method to regulating QI has not been found.In a word,it is of great necessity to develop a universal and efficient way to tune QI.This thesis uses STM-BJ to control and study the QI effect in the single-moleculescale electrical transport process in order to develop a universal control strategy.The specific research contents and results of this thesis are summarized as follows:1.It is the first time to realize the strategy of regulating single-molecule electrical transport QI based on the conjugation transition.By studying the electrical transport properties of the keto-enol form under different bias voltages,we found that the charge injection effect of the electric field can realize the manipulation of the thermodynamic driving force and energy barrier of tautomerism.Thus,the tautomeric system can realize the reversible switch between the non-conjugated system and the π-conjugated system at room temperature,and then realize the regulation of single-molecule electrical transport QI.At the same time,it is expected that the keto-enol tautomerism reaction can be designed as a molecular device with a high switching ratio.2.The basis for light-induced decoherence to regulate destructive quantum interference(DQI)is established for the first time.By introducing laser as a decoherence source,we studied the influence of laser on the QI effect of singlemolecule electrical transport,realized the laser control strategy on DQI effect,and extended this strategy to different molecular systems.By verifying polarization experiment and temperature control experiment,it is preliminarily concluded that the inhibition effect of laser on QI comes from the decoherence mechanism,which provides a new idea for regulating the QI effect of single-molecule electrical transport.