Covalent Ag–C Bonding Contacts from Unprotected Terminal Acetylenes for Molecular Junctions

Abstract

Robust molecule–metal linkages are essential for developing high-performance and air-stable devices for molecular and organic electronics. In this work, we report a facile method for forming robust and covalent bonding contacts between unprotected terminal acetylenes and metal (Ag) interfaces. Using this approach, we study the charge transport properties of conjugated oligophenylenes with covalent metal–carbon contacts to silver electrodes formed from unprotected terminal acetylene anchors. We performed single molecule charge transport experiments and molecular simulations on a series of arylacetylenes using gold and silver electrodes. Our results show that molecular junctions on silver electrodes spontaneously form silver–carbynyl carbon (Ag–C) contacts, resulting in a nearly 10-fold increase in conductance compared to the same molecules on gold electrodes. Overall, this work presents a simple, new electrode–anchor pair that reliably forms molecular junctions with stable and robust contacts for molecular electronics.

Single‐Molecule Electrochemical Transistors

“…However, the main disadvantage of the Ni contacts is the small potential window, which is limited by the Ni oxidation at a positive potential. Other metals, such as Ag, [77,78] Pt, [79] Cu, [80] and semiconductor Si [81] have been widely developed in single-molecule functional devices, which are expected to improve the diversity for the future SMECTs. Besides metal contacts, carbon-based electrodes, for example graphene, have also been used in SMECTs.…”

Using automated synthesis to understand the role of side chains on molecular charge transport

“…2a ) using a custom-built scanning tunneling microscope-break junction (STM-BJ) instrument, as previously described 10 , 11 . STM-BJ has been used in prior work to study single-molecule charge transport as a function of backbone length 10 , 12 , chemical substituents 13 , 14 , molecular conformation 15 , 16 , and anchor-electrode contacts 17 . Prior work has shown that alkyl side chains alter backbone conformation 16 , thereby affecting molecular conductance.…”

“…Recent work has reported that additional conductance states may arise from in-backbone molecule-electrode linkages 9 , 21 – 24 , in situ dimerization 17 , 25 – 27 , or intermolecular interactions 28 – 30 . To investigate the origin of the high G state, we synthesized the non-C2-symmetric terphenyl derivative R6-H containing only one terminal anchor using automated iterative cross-coupling (Fig.…”

Using Automated Synthesis to Understand the Role of Side Chains on Molecular Charge Transport

“…10,11 STM-BJ has been used in prior work to study single-molecule charge transport as a function of backbone length, 10,12 chemical substituents, 13,14 molecular conformation, 15,16 and anchor-electrode contacts. 17 Prior work has shown that alkyl side chains alter backbone conformation, 16 thereby affecting molecular conductance. Here, we used STM-BJ to systematically understand the role of side chain length and composition in the molecular library generated by automated synthesis.…”

“…Recent work has reported that additional conductance states may arise from in-backbone molecule-electrode linkages, 9,[18][19][20][21] in situ dimerization, 17,[22][23][24] or intermolecular interactions. [25][26][27] To investigate the origin of the high G state, we synthesized the non-C2-symmetric terphenyl derivative R6-H containing only one terminal anchor using automated iterative cross-coupling (Fig.…”