# Triplet Excitons Unlock Electroluminescence from Insulating Lanthanide Nanocrystals for Light-Emitting Diode Applications

## TL;DR

Researchers enabled electrically driven light emission from insulating lanthanide nanocrystals by using molecular engineering to transfer energy efficiently.

## Contribution

The study introduces a novel method to overcome the insulating nature of lanthanide nanocrystals for electroluminescence.

## Key findings

- Functionalized ligands enabled efficient triplet exciton transfer to lanthanide ions.
- Multicolor electroluminescence was achieved with high power and quantum efficiency.
- This approach opens new opportunities for electrically driven luminescence in insulating systems.

## Abstract

Lanthanide nanocrystals hold exceptional promise for electroluminescence applications due to their unique optical properties. However, their intrinsic insulating character and localized 4f orbitals severely restrict carrier injection, thereby hindering direct electrical excitation. In a recent study published in Nature, Tan and colleagues circumvented this fundamental bottleneck via molecular engineering of the nanocrystal surface. They developed a series of functionalized ligands (e.g., carbazole-phosphine oxide) to establish an electroactive interface, facilitating efficient transfer of electro-generated triplet excitons to lanthanide ions. Notably, a wide-ranging multicolor electroluminescence from lanthanide nanocrystals was achieved for the first time, exhibiting high power efficiency and external quantum efficiency. These findings provide new opportunities for electrically driven luminescence in lanthanide nanocrystals or other insulating systems.