Molecular electronics: a possible solution beyond Moore's Law

Molecular electronics is the science that studies the quantum behavior of electrons tunneling through molecules, where the electrical properties of a single molecule are intrinsic fingerprint properties closely related to its structure. Through the construction of electrode-molecule-electrode junction (molecular junction), connecting a single molecule to external circuits provides an opportunity for the development of new operational strategies for future electronic devices suppressing possible solutions beyond Moore's Law.

In a new paper published in the International Journal of Extreme Manufacturing, a team of researchers, including Prof. Junyang Liu, Dr. Yi Zhao, Prof. Wenjing Hong and Prof. Zhongqun Tian et al. from the School of Chemistry and Chemical Engineering of Xiamen University, have summarized the fabrication, characterization and functionalization in molecular electronics. This team is working to develop instruments for single-molecule electrochemistry, spectroscopy, and charge transport characterization. The ultimate goal of their highly interdisciplinary research is to design and synthesize materials from the interplay of chemistry, physics, and engineering at single-molecule scale. In this article, they revolve around the basic model molecular junction of molecular electronics, comprehensively summarize the fabrication methods of molecular junctions and discuss the characterization and regulation of molecular electronics at the atomic scale. In addition, they discuss the functionalization of molecular junctions, i.e., various molecular devices, including molecular rectifiers, optical switches, transistors, and outlook some challenges and opportunities in this field.

Prof. Junyang Liu, Dr. Yi Zhao, Prof. Wenjing Hong and Prof. Zhongqun Tian have identified a few critical challenges in the field of fabrication, characterization and functionalization of molecular electronics as follows:

"Since the size of a single molecule is usually at the nanometer or even sub-nanometer scale, how can the connection between individual molecules and external macroscopic measuring instruments be realized?"

"The access of molecules to the external test system is mainly achieved through the construction of metal nanogap. At present, the construction methods of molecular junction (electrode-molecule-electrode junction) mainly include two types, one is the static molecular junction with fixed gap, and the other is the dynamic break junction technology based on the repeated opening and closing of electrodes to realize the repeated construction of molecular structures."

"How does molecular electronics characterize and regulate individual molecules in molecular junctions?"

"At present, the electrical properties of single molecules can be characterized by the construction of some molecular structures supplemented by the construction of related test devices. For example, our research group has realized the independent research and development and construction of scanning tunneling microscope break junction (STM-BJ), atomic force microscope break junction (AFM-BJ), mechanically controllable break junction (MCBJ) instruments, and provided external single-molecule electrical testing assistance. Further, the combination with other instruments such as Raman spectroscopy, ultrafast spectroscopy, electron microscopy characterization, etc., can further explore the structure-activity relationship of physical and chemical processes at the single-molecule scale."

Finally, the researchers suggest that starting from the ultimate goal of molecular electronics, how to implement the prototypical molecular junctions into functional circuit components is the core problem in future exploration. How to form a stable and reliable molecular junction with an adjustable molecule-electrode interface is still the key challenge, whereas the molecular electronic device can really be moving forward into the application after well solved. Therefore, the next crucial step for molecular electronics is to develop manufacturing technologies to realize the construction of integrated molecular electronic devices with high stability and reproducibility.

About IJEM:

International Journal of Extreme Manufacturing (IF: 10.036) is a new multidisciplinary, double-anonymous peer-reviewed and fully open access journal uniquely covering the areas related to extreme manufacturing. The journal is devoted to publishing original articles and reviews of the highest quality and impact in the areas related to extreme manufacturing, ranging from fundamentals to process, measurement and systems, as well as materials, structures and devices with extreme functionalities.

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