Revolutionizing Electronics with Ladder-Like Molecules

Researchers at the University of Illinois Urbana-Champaign have developed a new method for controlling molecular conductance by using molecules with rigid structures, specifically ladder-type molecules. As electronic devices continue to miniaturize, traditional silicon-based microchips are hitting physical size limits, which disrupts the trend of doubling transistor density every two years, as predicted by Moore's Law. Molecular electronics, which involves using individual molecules as components in electronic devices, offers a potential solution but requires precise control of electrical currents.

Led by Charles Schroeder, James Economy Professor of Materials Science and Engineering and Chemical and Biomolecular Engineering, and supported by postdoc Xiaolin Liu and graduate student Hao Yang, the research team introduced a novel "one-pot" technique for synthesizing shape-persistent molecules. Their findings, published in Nature Chemistry, show that using rigid ladder-type molecules can stabilize electronic properties, which is essential for reliable performance in molecular electronics.

In this field, the flexibility of organic molecules and their various conformations can lead to significant fluctuations in conductance. Liu notes that different molecular shapes can result in conductance varying by as much as 1,000 times. To address this issue, the team focused on ladder-type molecules, which have a rigid, fixed structure that minimizes conductance variation.

These ladder-type molecules have an uninterrupted sequence of chemical rings that hold the molecule in a specific shape, ensuring consistent electronic behavior. This stability is crucial for creating functional electronic components, where uniform conductance across billions of devices is necessary.

One significant challenge in molecular electronics has been achieving consistent conductance, which hampers the commercialization of these technologies. The team's one-pot ladderization synthesis method allows for creating a wide range of chemically diverse, charged ladder molecules using simple, commercially available materials, unlike traditional methods which are more complex and expensive.

Additionally, the team applied their synthesis method to create a butterfly-shaped molecule, which also features a rigid backbone and constrained rotation. This demonstrates the broader applicability of their approach and could lead to new functional materials and more reliable electronic devices in the future.