IISc's new molecular tech mimics brain functions

BENGALURU: Scientists from Indian Institute of Science (IISc) reported an advance in the long quest to move electronics beyond silicon, by creating molecular-scale devices that can adapt their behaviour and perform multiple computing functions within the same material.

In a study that brings together chemistry, physics, and electrical engineering, the IISc team has demonstrated tiny electronic devices built from specially-designed molecules that can switch roles depending on how they are electrically stimulated. The same device can function as a memory unit, a logic gate, an analogue processor, or even an artificial synapse that mimics learning in the brain.

For decades, researchers have explored molecular electronics as a way to shrink devices further than conventional silicon allows. The idea was appealing, but in practice molecules inside a device interact in complex ways. Electrons flow, ions rearrange, and small changes in structure can produce unpredictable results. As a result, controlling molecular behaviour reliably has remained difficult.

At the same time, neuromorphic computing that aims to build hardware inspired by brain, has struggled to find materials that can naturally combine memory and computation. Existing systems rely on oxide materials that imitate learning by engineered switching, rather than learning being intrinsic property of the material.

The new work from IISc suggests these two challenges may be addressed together. The team, led by Sreetosh Goswami, assistant professor at CeNSE, designed and synthesised 17 variants of ruthenium-based molecular complexes. By carefully altering chemical ligands and surrounding ions, the researchers were able to tune how electrons move through thin molecular films.

These subtle chemical changes allowed the devices to display a wide range of behaviours, from sharp digital switching to smooth analogue responses, across many levels of electrical conductance. "It is rare to see adaptability at this level in electronic materials," Goswami said. "Here, chemical design directly determines how computation happens."

The molecular synthesis was carried out by Pradip Ghosh, Ramanujan Fellow at CeNSE, along with Santi Prasad Rath, a former doctoral student. Device fabrication and testing were led by Pallavi Gaur, the study's first author and a PhD student. "What stood out was how much functionality was hidden in the same system," Gaur said. "With the right chemistry, one device can store information, process it, or even learn and forget."