Researchers Create New Path To Highly Precise NIR LEDs

Researchers have developed a new way to make ultra-narrow band, near‑infrared LEDs by “electrically powering” materials that normally do not conduct, using attached organic molecules that act as molecular antennas. The work opens a path to highly precise light sources for deep‑tissue medical imaging, optical communication, and chemical or biological sensing.

Core scientific breakthrough

Researchers at the University of Cambridge’s Cavendish Laboratory discovered how to drive electrical current into lanthanide‑doped nanoparticles (LnNPs), a material family previously considered unusable in conventional LEDs because they are strong electrical insulators. By attaching specific organic dye molecules to the nanoparticle surface, they circumvent the need for current to flow through the nanoparticles themselves while still getting them to emit light efficiently.

Molecular antenna mechanism

The team used an organic dye called 9‑anthracenecarboxylic acid (9‑ACA), which binds to the LnNP surface and acts as a molecular antenna that receives injected electrical charges. When energized, 9‑ACA reaches an excited triplet state and then transfers that energy with more than 98% efficiency into the lanthanide ions in the insulating nanoparticle, triggering bright, highly pure light emission.

Performance and optical advantages

The resulting “LnLEDs” switch on at about 5 volts, a relatively low operating voltage for such devices. Their electroluminescence has an extremely narrow spectral width, especially in the second near‑infrared window (NIR‑II), making the emission much purer than many competing technologies such as quantum dots.

Potential applications

Because NIR‑II light penetrates deeply into biological tissue and the emission is so spectrally clean, the devices could be used in deep‑tissue biomedical imaging, real‑time organ function monitoring, and precise activation of light‑controlled drugs via tiny injectable or wearable sources. The same spectral purity and stability also suit high‑speed optical communication links and highly selective sensors for chemicals or biomarkers in diagnostics and environmental monitoring.

Future directions and impact

In first‑generation prototypes, the external quantum efficiency in the NIR‑II range exceeds 0.6%, which is regarded as promising for a brand‑new platform based on insulating nanoparticles. The authors emphasize that the underlying design principle is versatile, allowing many combinations of organic antennas and insulating nanomaterials, potentially enabling tailored optoelectronic devices for yet‑unexplored applications.

The full research paper is published in Nature here.

Image above: a, Schematic illustration of the device architecture of LnLEDs with a close-up schematic of LnNP@9-ACA nanohybrids. b, Simplified schematic showing electron and hole injection through organic molecules to turn on lanthanide ions in an insulating host lattice. CB, conduction band; VB, valence band. c, Normalized EL spectra of LnLEDs. a.u., arbitrary units. d, Reported FWHMs of the EL at different wavelengths from different types of LED, including LnLEDs and QD LEDs. Source

Special thanks to Isaac Meisels for sharing this advancement.

David Shiller

David Shiller is the Publisher of LightNOW, and President of Lighting Solution Development, a North American consulting firm providing business development services to advanced lighting manufacturers. The ALA awarded David the Pillar of the Industry Award. David has co-chaired ALA’s Engineering Committee since 2010. David established MaxLite’s OEM component sales into a multi-million dollar division. He invented GU24 lamps while leading ENERGY STAR lighting programs for the US EPA. David has been published in leading lighting publications, including LD+A, enLIGHTenment Magazine, LEDs Magazine, and more.

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