Just as we move away from a hot place to a comfortably cool one, so do charge carriers (electrons and holes) in atoms. If you heat one end of a metal bar, the carriers migrate towards the cooler end. As some charged particles migrate, there develops a pushback against the migration, leaving the two ends with a difference in electrical charge — one end positive, the other negative. When this happens, you have a voltage.This was discovered in 1821 by Thomas Johann Seebeck, a German physicist of Baltic extraction. Seebeck was experimenting with circuits made of different metals when he noticed that a temperature difference could produce a magnetic effect near a compass needle — an observation that was later understood to arise from an electric current generated by heat.He established, for the first time, a direct link between heat and electricity and laid the foundation for the science of thermoelectricity. Since then, the ‘Seebeck effect’ has been taught in high school physics textbooks.Most metals produce Seebeck coefficients of only a few tens of microvolts per kelvin. Even good semiconductors typically manage a few hundred microvolts per kelvin. A few millivolts per kelvin was generally considered the upper end for crystalline solids.Much larger values were the preserve of liquids and soft materials such as electrolytes, ionic gels and hydrogels, where ions rather than electrons move under a temperature gradient.Now, a team led by Prof Bivas Saha of the Jawaharlal Nehru Centre for Advanced Scientific Research (JNCASR), working with researchers from the University of Sydney and the Indian Institute of Science (IISc), has reported a Seebeck coefficient exceeding –124.6 millivolts per kelvin near room temperature in a thin film of scandium nitride, which is of industrial significance.That is several hundred times larger than the values normally associated with inorganic semiconductors, and nearly a hundred times beyond the previously accepted ceiling for crystalline solids.The findings, published in Science, amount to something of a thermoelectric surprise: A solid crystal behaving, in one important respect, more like an electrolyte.Carefully engineeredThe hero material — scandium nitride, or ScN — is a refractory transition-metal nitride. The researchers grew films of it on magnesium oxide substrates using ultra-high vacuum magnetron sputtering. Then came the crucial intervention.ScN naturally contains free electrons, partly because of oxygen impurities. The scientists deliberately introduced magnesium atoms, which compensated for these electrons. The result was what scientists call a heavily doped, highly compensated semiconductor.In such a material, positive and negative dopant atoms are present in nearly equal numbers and are randomly distributed through the crystal. “We were not looking for a record-breaking number,” Prof Saha said. “We were trying to understand how disorder and charge compensation reshape electronic transport in scandium nitride.”There was another surprise. The effect became stronger as the films were made thinner. The researchers have already taken the first step towards developing a device based on the phenomenon.They fabricated a prototype photon sensor using a thin film of the highly compensated ScN, with two chromium contacts. A laser was shone on one of the contacts, heating it slightly and creating a tiny local temperature difference across the device. That small difference generated a measurable voltage corresponding to a Seebeck response of –102.4 millivolts per kelvin. The response was fast and repeatable, and the material showed no apparent degradation after repeated cycles.Industrial significanceThe immediate implication is for extremely sensitive temperature and heat detectors. A material that produces a large voltage in response to a minute temperature difference can potentially detect very small thermal disturbances without requiring complicated amplification. That could be valuable in thermal imaging, heat-flux measurement and bolometers — devices that detect radiation by measuring the heating it produces. It could also matter for the rapidly growing internet-of-things universe, where billions of small sensors need to become cheaper, more sensitive and less power-hungry.Perhaps the most intriguing possibilities lie in quantum technologies. The researchers believe that with further optimisation, such devices could potentially approach single-photon detection near room temperature.At present, detecting individual photons often requires extremely sophisticated detectors and, in many cases, cryogenic cooling. The ScN discovery, therefore, points towards a tantalising possibility: Quantum-grade sensing based on an unusual form of thermoelectric amplification in an ordinary-looking semiconductor thin film. That possibility also resonates with India’s National Quantum Mission, which is seeking to build capabilities not only in quantum computing, but also quantum sensing and metrology.At a recent National Conference on Quantum Biotechnology at IIT-Bombay, scientists, clinicians, start-ups and industry representatives discussed how advances in quantum sensing could be translated into diagnostics, biomedical imaging, drug discovery and precision medicine.Sensing advancesThe underlying message is that the next quantum revolution may not depend only on building bigger quantum computers. It may also come from building instruments that can detect things that existing instruments simply cannot fathom. Prof Kasturi Saha, Project Director of QMet Tech Foundation at IIT-Bombay, captured the challenge neatly: Quantum biotechnology is where advances in sensing meet real clinical needs.The scandium nitride discovery is not yet a commercial technology, and considerable work will be needed to understand the physics, optimise the material and manufacture reliable devices. But its industrial significance lies precisely in the fact that it opens a new materials design strategy.For decades, engineers seeking superior thermoelectric materials largely tried to improve an existing balancing act between electrical conductivity, heat conductivity and thermopower. This work suggests another route: Engineer the right kind of disorder and charge compensation without sacrificing crystalline quality.If that strategy can be reproduced in other materials and translated into scalable devices, it could lead to a new class of ultrasensitive thermal and photon sensors — and perhaps give India’s quantum technology programme a promising materials platform of its own.Published on September 7, 2026