Researchers developed quantum dot light-emitting diodes that are free of heavy metals. [Image: Curtin University]
As a display technology, quantum dot light-emitting diodes (QLEDs) have several advantages, including light-emitting efficiency, wavelength tunability and cost. However, most quantum dots are made of heavy metal ions like cadmium, which are toxic to humans and the environment, limiting their practical applications.
Now, researchers in China and Australia have created a new type of heavy-metal-free quantum dot with pure-blue emissions and near-unity photoluminescence quantum yield (Nature, doi: 10.1038/s41586-025-08645-4). The work paves the way for the development of eco-friendly QLEDs for high-definition displays.
Pure, vibrant blue light
Quantum dots made with an alloy of zinc selenide and tellurium (ZnSeTe) have shown promise as a safer alternative to conventional metal-based quantum dots. But increasing the tellurium content to shift the emission peak toward the pure-blue region leads to aggregation of tellurium atoms, resulting in color impurity and structural instability.
The researchers discovered a strategy that incorporates sulfur, in complex with the organophosphorus molecule triphenyl phosphite, into the precursors of ZnSeTe quantum dots. The sulfur atoms inhibit the formation of tellurium aggregates by redistributing the placement of charge carriers around the tellurium atoms, promoting the formation of evenly alloyed ZnSeTeS quantum dots.
“Our research team has developed a new type of quantum dot that matches or even outperforms traditional cadmium-based QLEDs, but in a safer and more sustainable way,” said study author Guohua Jia, Curtin University, Australia, in a press release accompanying the research. “Our quantum dots emit a pure and vibrant blue light with an impressive 24.7% efficiency, which is among the highest recorded for blue QLEDs.”
Their performance rivals state-of-the-art, commercially available cadmium-based blue QLEDs, with the added benefit of being safe for the environment.
Rivals the state of the art
The resulting homogeneously alloyed ZnSeTeS quantum dots also show a narrow spread of emitted wavelengths (17 nm centered at 460 nm) and a long operational half-lifetime close to 30,000 hours with a luminance of 100 candela per square meter. Their performance rivals state-of-the-art, commercially available cadmium-based blue QLEDs, with the added benefit of being safe for the environment.
“We believe that our study will have a profound impact across the breadth of devices known as optoelectronics, which either produce light or use light to perform their functions,” said Jia. “These results represent a new frontier in display technology and put us on a path toward superior displays with high color purity, operational stability and eco-friendliness.”