Electrolyte Effect In The Destructive Quantum Interference Azulene Monomolecular Electrochemical Transistor

Quantum interference effect provides unique opportunities for nanoscale charge transport and has become an emerging field of molecular electronics.Due to the existence of quantum interference between particles,it is possible to control charge transport of single molecule through structural changes and environmental changes,which may cause charge transport state to transition from conductive to insulating state,and in future functional single-molecule devices Provide promising applications.Especially for molecules with destructive quantum interference,due to the ultra-low conductivity of destructive quantum interference molecules,the use of electrochemical gating to transform them into constructive quantum interference can increase the conductance,which is of great significance to the development of single-molecule electrical devices.In the related research of electrochemical gating,people’s attention is usually on the effect of potential on the single molecule charge transport process.Electrolyte,as an essential component of electrochemical gating,has important effects on molecular junctions.The impact of transport has received little attention.In the process of electrochemical gating,in addition to the provider of ions,the electrolyte may also have a solvation with the molecule to achieve the manipulation of charge transport process without applying a potential.Therefore,this paper uses Single-molecule electrical measurement technique to deeply study the effect of electrolyte on charge transport process of the molecular junction constructed by destructive quantum interference molecules and the performance of corresponding single-molecule electrochemical devices.The main tasks are as follows:1.The self-built scanning tunneling microscope break junction device was used to construct the molecular structure of azulene under the environment of imidazole ionic liquid,and its conductance were measured.We found that the azulene molecule with destructive quantum interference in the imidazole ionic liquid,the conductance increased 18 times compared to the mesitylene,and the azulene molecule with constructive quantum interference exhibit similar conductance.Through a series of experiments,we determined that the imidazole cations in the ionic liquids have a regulating effect on the destructive quantum interference during the transport process of the azulene molecule.Theoretical calculations show that the imidazole cation can adjust the destructive quantum interference in the process of charge transport to constructive quantum interference through the interaction with the azulene,thereby greatly improving the charge transport performance of the molecular junction.2.Based on the above findings,we further constructed Single-molecule electrochemical transistors based on the azulene with destructive quantum interference to study the effect of electrolyte on device performance.We found that in the propylene carbonate electrolyte,the charge transport of the azulene molecular junction was dominated by the destructive quantum interference,and the molecular junction conductance increased 18 times with the potential change in the range of 0～0.8 V;In the imidazole ionic liquid,the molecular junction conductance changes only 2 times in the same potential interval,which further confirms that the destructive quantum interference is converted to constructive quantum interference due to the interaction between the imidazole cation and the azulene,the electron’s transmission function curve is relatively smooth,which causes the change of the conductance with the potential to decrease.