Two independent research teams have devised similar strategies to electrically control the light emission from lanthanide ions contained within insulating nanoparticles (Nature, doi: 10.1038/s41586-025-09601-y and 10.1038/s41586-025-09717-1). By attaching organic molecules to the surface of the nanoparticles, the two groups have created light-emitting diodes (LEDs) that generate ultrapure light at wavelengths that can be tailored to the needs of the application.

Adding organic semiconductors

Nanoparticles doped with lanthanide ions are known for their ability to emit bright and stable light over a narrow and tunable spectral range. However, the difficulty of generating excited states in these insulating materials has prevented the development of practical devices. "These nanoparticles are fantastic light emitters, but we couldn't power them with electricity," says Akshay Rao of the University of Cambridge, UK, who led one of the studies. "It was a major barrier preventing their use in everyday technology."

The solution adopted by the two research groups was to augment the nanoparticles with carefully engineered organic molecules. When activated with an electrical current, these organic semiconductors capture energy from the charge carriers to create an excited triplet state. By matching this triplet state to the energy levels of the lanthanide ions, energy is efficiently transferred between the two to drive light emission from the lanthanide ions.

New material for optoelectronics

Both teams showed that these hybrid nanostructures can be incorporated into a conventional LED structure, allowing light emission to be activated at voltages below 5 V. The Cambridge researchers engineered their hybrid material to luminesce in the near infrared, specifically at the shorter wavelengths that are needed for biomedical imaging and optical communications. These devices emitted light over a much narrower spectral range than those based on quantum dots, which are the usual choice at these wavelengths.

The other team, which includes researchers from Singapore and China, designed its hybrid materials to emit light across the visible spectrum and up to wavelengths of 1000 nm. They showed that the color of light emission could be altered by controlling the type and concentration of dopants within the nanostructures, with no changes needed to the device architecture.

These proof-of-concept devices achieve external efficiencies that rival those of other emerging technologies, although more work will be needed to deliver the performance needed for practical applications. The brightness of the devices is also constrained by the time it takes a lanthanide ion to release a photon, but it could be improved by optimizing both the light-emitting materials and the device design.

If these challenges can be overcome, this new type of LED offers a versatile and practical solution for many photonics applications. "We've unlocked a whole new class of materials for optoelectronics," said Yunzhou Deng, a member of the Cambridge team. "They will allow us to create devices with tailored properties for applications we haven't even thought of yet."