Image showing the smart molecule switches from a scanning tunneling microscope. Each bright molecule represents a single switch. (Image Credit: Dr. Kunal Mali, KU Leuven)


Data storage could one day be made up of smart molecules, providing up to 100 times more storage space than the ones we see today. An international team of researchers at Lancaster University have discovered a single-molecule switch capable of behaving like a transistor while making it possible to store binary data like the 1s and 0s used in computing. The researchers published their findings in the journal Angewandte Chemie.


The molecule measures approximately five square nanometers, which means that over a billion of them can fit into the cross-section of a human hair.


Researchers behind this discovery believe that these molecules could provide up to 250 terabits per square inch of data density, which is around 100 times the storage density found in traditional hard drives. Even though the team doesn't expect this molecule to be utilized in real hard drives, the study is a crucial proof of concept that offers new insight and could bring everyone one step closer to the beginning of molecular electronics.


Using a small electrical input in the study, molecules of an organic salt can be switched to have a bright or dark appearance, which provides binary information. Most importantly, this information can be read, written and erased in normal air pressures and at room temperature. These features are important for applications of the molecules in computer storage devices. Previous research involving molecular electronics for the same type of applications has been conducted at very low temperatures in a vacuum.


"There is an entire list of properties that a molecule has to possess to be useful as a molecular memory. Apart from being switchable in both directions under ambient conditions, it has to be stable for a long time in the bright and dark state, and also spontaneously form highly ordered layers that are only one molecule thick, in a process called self-assembly. Ours is the first example that combines all these features in the same molecule." said Dr. Stijn Mertens, Senior Lecturer in Electrochemical Surface Science at Lancaster University and lead researcher on the study.


During experiments in the laboratory, the team used tiny electric pulses in a scanning tunnel microscope to switch every single molecule from bright to dark. Afterward, they read and erase the information by pressing a button.


An image showing what the structure of the molecule switch looks like. (Image Credit: Dr. Kunal Mali, KU Leuven)


While switching, the electric pulse alters how the cation and anion in the organic salt stack on top of each other, causing the molecules to have a dark or bright appearance. Other than the switching, the molecules' ordering is also important: while being self-assembled, they end up in a highly ordered structure (2D crystal), without using costly manufacturing equipment, which is often used in today's electronics.


"Because chemistry allows us to make molecules with sophisticated functions in enormous numbers and with atomic precision, molecular electronics may have a very bright future," said Dr. Mertens.


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