A detector that detects energy from near-infrared to thermal radiation at room temperature has been developed by Chinese researchers working with physicists from the Military University of Technology in Warsaw.
The key is the unusual material Nb3I8, a crystal just a few atoms thick with unique quantum properties.
Infrared and thermal detectors are widely used in the military, emergency services, construction and industry, but today’s most sensitive sensors must be cooled to very low temperatures. They are expensive, fragile and difficult to integrate into everyday electronics.
But as interest grows in applications ranging from disaster-response drones to gas-leak monitors and smart-home systems, the need for compact, low-cost, room-temperature sensors has become increasingly urgent.
The study, published in Nature Communications (https://doi.org/10.1038/s41467-025-63983-1), asks whether a single, inexpensive detector can operate at room temperature across an exceptionally broad infrared range—from short wavelengths used in telecommunications to long wavelengths emitted by warm bodies or leaking gases.
Conventional semiconductor detectors such as HgCdTe or InSb offer high sensitivity but require complex manufacturing and cryogenic cooling. Bolometer-based thermal cameras are cheaper but slow, and their performance degrades sharply when the system is miniaturised.
The team instead turned to a quantum material with flat electronic energy bands. They selected Nb₃I₈, a layered niobium iodide crystal that can be thinned to a few atomic layers. Its electrons move through a kagome-lattice structure that produces flat energy bands—regions where electrons have many available states but move slowly. Such bands make the material highly efficient at absorbing light and retaining the absorbed energy.
A moth’s dual visual and thermal sensing system partly inspired the research. Detailed quantum-mechanical calculations indicated that Nb₃I₈ not only hosts flat electronic bands but also shows flat bands for phonons, meaning it absorbs infrared photons effectively while conducting heat poorly.
As a result, the detector behaves like a standard photodetector at short wavelengths, and like a bolometer at longer wavelengths, sensing small temperature-driven changes in electrical resistance.
Experiments showed that a single Nb₃I₈ detector responds to wavelengths from roughly 2.5 to 20 micrometres, covering both telecommunications bands and the operating range of thermal cameras. It works at room temperature without liquid-nitrogen cooling, opening the door to simpler and cheaper infrared modules.
Researchers also built proof-of-concept devices. The same detector captured images of objects illuminated by a lamp and registered passive images of heated components. It detected the weak thermal radiation of a human hand and functioned as a flexible, skin-mounted temperature or proximity sensor. In separate trials, it performed well in infrared gas-leak detection.
The work remains at the single-detector stage. Engineers still need to develop pixel arrays, integrate the material with electronics and optics, and test long-term durability. However, if the technology scales to mass production, it could lead to inexpensive thermal cameras for cars, smartphones and home-automation systems.
Compact, low-power infrared detectors are also key to autonomous-vehicle navigation, drone inspections, methane-leak monitoring and energy-efficiency assessments in buildings. (PAP)
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