Simple trick lets pure blue quantum dots maintain their performance without cadmium

A simple structural tweak has dramatically enhanced the colour clarity and stability of heavy metal-free blue quantum dots. By incorporating sulfur into the ecofriendly zinc–selenium–tellurium nanocrystal lattice, researchers in China produced pure blue quantum dot LEDs (QLEDs) that rival the performance of state-of-the-art ones.

‘Quantum dots are semiconductor nanocrystals with size-dependent optical and electronic properties,’ explains Yajie Dong, an optoelectronics researcher at the University of Central Florida who wasn’t involved in the research. The physical size of these particles confines the electrons into such a small space that quantum effects dominate their behaviour, leading to tuneable optical and electronic properties that are heavily exploited in the production of coloured LEDs.