Molecular Memory Project
For more than three decades, improvements in computer hardware have been rooted in the top-down miniaturization of transistors in integrated circuitry, leading to a reduction in minimum feature sizes from one micrometer to ten nanometers. Further miniaturization of circuit elements based on existing “hammer-and-chisel” techniques like photolithography is becoming increasingly difficult and cost-prohibitive, highlighting the need for development of alternative fabrication strategies to keep pace with increasing technical demand.
The continuous demand for increased computing power has led to a deviation from conventional electronic devices typically made up of bulk materials and has grown to encompass the use of single molecule components in "molecular electronics." The integration of molecular species in circuits provides increased high degrees of tunability not typically found through alterations from bulk materials.
One promising application of molecular electronics is data storage through the form of molecular memory. Molecular switches, where the electronic states of the incorporated molecules can be controlled externally, may be realized for reliable molecular electronic circuits.
One prospective approach that has gained considerable scientific momentum over the past decade is the pursuit of data storage technologies based on individual molecules as memory elements. Towards this end, prior work in our laboratory has focused on exploring the use of switchable, mechanically interlocked molecules (MIMs) as tunnel junctions for data storage media. Our success in implementing self-assembled monolayers of these molecules in a 160 kbit memory device has nevertheless shed light on a number of technical obstacles (e.g. irregular distribution of memory elements and their susceptibility to rapid weathering) that must be addressed before commercial de-velopment of molecular electronic devices can begin.
Extensive work has been done to create a wide range of switchable mechanically interlocked molecules (MIMs), particularly bistable catenanes and rotaxanes. The electrochemical addressability of these compounds have shown string promise in molecular memory devices due to their inherent ‘on’ and ‘off’ configurations following an external stimulus. Our success in the incorporation of bistable MIMs as tunnel junctions for molecular storage media has demonstrated that modifications to these compounds can create species ideal for molecular electronic devices.