Robust Sub‐5 Nanometer bis(Diarylcarbene)‐Based Thin Film for Molecular Electronics and Plasmonics

Abstract

In miniaturized electronic and optoelectronic circuits, molecular tunnel junctions have attracted enormous research interest due to their small footprint, low power consumption, and rich molecular functions. However, the most popular building blocks used in contemporary molecular tunnel junctions are thiol molecules, which attach to electrode surfaces via a metal‐thiolate (MS) bond, showing low stability and usually quick degradation within several days. To pave the way for more widely applicable and stable molecular tunnel junctions, there is a need to develop new molecular anchoring groups. Here, this work demonstrates robust and air‐stable molecular tunnel junctions with a sub‐5 nanometer bis(diarylcarbene)‐based thin film as the tunneling barrier, which anchors to the electrode surface via a AuC bond. The bis(diarylcarbene)‐based molecular tunnel junctions exhibit high thermal stability against heating up to 200 °C and long storage lifetime over 5 months in an ambient environment. Both electrical and optical performance of these bis(diarylcarbene)‐based molecular junctions are characterized systematically, showing similar behaviors to thiol‐based junctions as well as largely improved emission stability. This research highlights the excellent performance of bis(diarylcarbene)‐based molecular tunnel junctions, which could be useful for applications in molecular electronics and plasmonics.

Revealing the correlation relation between conducting channels in self-assembled monolayer tunnel junctions

“…1d, the spectra of the light emission blue shift together with the intensity increase as the bias increases from 1.6 V to 2.0 V, which agrees with the previous reports. 24,31…”

“…21–23 On the other hand, in molecular monolayer tunnel junctions, light emission mainly originates from the excitation of surface plasmons on the metallic electrode. 24–32 Interestingly, light emission in molecular monolayer tunnel junctions is not uniform over the entire junction area, but from individual spots due to the non-uniform electrical contact between the electrode and the molecular monolayer. 24,27–29,31 Under constant bias, the light emission intensity is proportional to the tunnelling current.…”

“…24–32 Interestingly, light emission in molecular monolayer tunnel junctions is not uniform over the entire junction area, but from individual spots due to the non-uniform electrical contact between the electrode and the molecular monolayer. 24,27–29,31 Under constant bias, the light emission intensity is proportional to the tunnelling current. Hence, the light emission spot in molecular monolayer tunnel junctions actually shows the place where the tunnelling current or a conducting channel locates, and the light emission intensity reflects the magnitude of tunnelling current at local spots (or conducting channels).…”

Molecular-Scale Electronics: From Individual Molecule Detection to the Application of Recognition Sensing

“…First, the analytical targets are currently limited to electronically conducting and small-sized molecules (<5 nm) for tunneling current measurement in SMJs. Second, current fabrication methods for SMJs often have limited reproducibility, unreliable contact, or inadequate binding of analytes onto the electrodes for reliable long-term measurement. , Third, achieving precise trapping, positioning, and orienting of target analytes within the nanogap of electrodes remains a persistent challenge, critical for consistent and accurate measurements. Additionally, while electrical tunneling sensors hold immense potential in next-generation sequencing technologies, correlating signal transformations with specific molecular processes presents obstacles in signal analysis …”