Preparation And Characterization Of The Molecular Tunnel Junctions Based On Self-assemble Of The Phenyl Deritives

Electrons transport across organic molecules depends strongly on the structure of the functional molecules. Understanding the relationship between electron transfer and molecular structure is valuable for constructing molecular devices. In this work, gallium was used as the electrode material. The molecular tunnel junctions were constructed by the capillary method which has been reported previously. The electricity of the molecular tunnel junctions has been tested, and the HOMO-LUMO energy gaps (HLG) of the molecules were also calculated.The current-voltage(I-V) curves of metal-molecule-metal junctions were measured, and the dI/dV-V curves were obtained based on the current-voltage(I-V) data. The energy gaps are determined by the position of abrupt change on the slope of the dI/dV-V curves.In our experiments, functional molecules such C₆H₄Br₂,C₁₂H₈Br₂,C₆H₆O₂,C₁₂H₁₀O₂,C₆H₈N₂,C₁₂H₁₂N₂,C₆H₄Cl₂,C₁₂H₈Cl₂,C₆H₄I₂,C₁₂H₈I₂,C₈H₆O₄ and C14H10O4 were explored. Typical nonlinear electric behavior of the metal-molecule-metal junctions was found at room temperature. The structures of the main chain, as well as the terminal groups of the molecules are affect the energy gaps of the tunnel junctions. While the molecules with the same backbone, the high electro-negativity of the terminal group made the harder electron transfer in the molecular tunnel junctions.The calculated results indicate that the HLGs behaved the same trend with the energy gaps obtained from experiment. The higher HLG makes the harder electron transfer in the molecular tunnel junctions. The results confirmed that the capillary method which we used to study the electricity of the functional molecules was reasonable.