In a brand new Nature Communications research, Columbia Engineering researchers report that they’ve constructed extremely conductive, tunable single-molecule gadgets through which the molecule is connected to leads through the use of direct metal-metal contacts. Their novel strategy makes use of gentle to regulate the digital properties of the gadgets and opens the door to broader use of metal-metal contacts that might facilitate electron transport throughout the single-molecule system.
The problem
As gadgets proceed to shrink, their digital elements should even be miniaturized. Single-molecule gadgets, which use natural molecules as their conductive channels, have the potential to resolve the miniaturization and functionalization challenges confronted by conventional semiconductors. Such gadgets provide the thrilling chance of being managed externally through the use of gentle, however — till now — researchers haven’t been capable of show this.
“With this work, we have unlocked a brand new dimension in molecular electronics, the place gentle can be utilized to regulate how a molecule binds throughout the hole between two metallic electrodes,” stated Latha Venkataraman, a pioneer in molecular electronics and Lawrence Gussman Professor of Utilized Physics and professor of chemistry at Columbia Engineering. “It is like flipping a change on the nanoscale, opening up every kind of potentialities for designing smarter and extra environment friendly digital elements.”
The strategy
Venkataraman’s group has been finding out the basic properties of single-molecule gadgets for nearly 20 years, exploring the interaction of physics, chemistry, and engineering on the nanometer scale. Her underlying focus is on constructing single-molecule circuits, a molecule connected to 2 electrodes, with different performance, the place the circuit construction is outlined with atomic precision.
Her group, in addition to these creating useful gadgets with graphene, a carbon-based two-dimensional materials, have identified that making good electrical contacts between metallic electrodes and carbon programs is a significant problem. One resolution can be to make use of organo-metallic molecules and devise strategies to interface electrical results in the metallic atoms throughout the molecule. In direction of this purpose, they determined to discover the usage of organo-metallic iron-containing ferrocene molecules, that are additionally thought of to be tiny constructing blocks on the earth of nanotechnology. Identical to LEGO items will be stacked collectively to create advanced buildings, ferrocene molecules can be utilized as constructing blocks to assemble ultra-small digital gadgets. The workforce used a molecule terminated by a ferrocene group comprising two carbon-based cyclopentadienyl rings that sandwich an iron atom. They then used gentle to leverage the electrochemical properties of the ferrocene-based molecules to type a direct bond between the ferrocene iron heart and the gold (Au) electrode when the molecule was in an oxidized state (i.e. when the iron atom had misplaced one electron). On this state, they found that ferrocene may bind to the gold electrodes used to attach the molecule to the exterior circuitry. Technically, oxidizing the ferrocene enabled the binding of a Au0 to an Fe3+ heart.
“By harnessing the light-induced oxidation, we discovered a strategy to manipulate these tiny constructing blocks at room temperature, opening doorways to a future the place gentle can be utilized to regulate the habits of digital gadgets on the molecular stage,” stated the research’s lead creator Woojung Lee, who’s a PhD scholar in Venkararaman’s lab.
Potential impression
Venkataraman’s new strategy will allow her workforce to increase the kinds of molecular terminations (contact) chemistries they will use for creating single-molecule gadgets. This research additionally reveals the power to activate and off this contact through the use of gentle to vary the oxidation state of the ferrocene, demonstrating a light-switchable ferrocene-based single-molecule system. The sunshine-controlled gadgets may pave the way in which for the event of sensors and switches that reply to particular gentle wavelengths, providing extra versatile and environment friendly elements for a variety of applied sciences.
The workforce
This work was a collaborative effort involving synthesis, measurements, and calculations. The synthesis was achieved primarily at Columbia by Michael Inkpen, who was a post-doc within the Venkataraman group and is now an assistant professor on the College of Southern California. All of the measurements have been made by Woojung Lee, a graduate scholar within the Venkataraman group. The calculations have been carried out each by graduate college students within the Venkataraman group and by collaborators from the College of Regensburg in Germany.
What’s subsequent
The researchers at the moment are exploring the sensible purposes of light-controlled single-molecule gadgets. This might embrace optimizing system efficiency, finding out their habits below completely different environmental circumstances, and refining further functionalities enabled by the metal-metal interface.
