Cd-free quantum dots remain stable through polymer co-extrusion at 200°C

October 03, 2016 // By Julien Happich
US company Crystalplex Corp. announced it was granted a U.S. patent for its "Passivated Nanoparticles" (No. 9,425,253) disclosing Sapphire-passivated quantum dots with improved stability.

Granted to inventors Lianhua Qu, Crystalplex's Chief Technical Officer and Gregory Miller, the patent protects processes for synthesizing an alloy gradient nanoparticle with a Zn:S shell and an outside coating of aluminium oxide that provides a barrier to environmental degradation.

In addition to providing improved photo, thermal, and environmental stability, the quantum dots demonstrate longer lifetimes, as the optically transparent aluminium oxide outer layer serves as a shield against degradation by humidity and oxygen. The passivation technology is applicable to Crystalplex's alloy gradient cadmium-free quantum dots, as well.

"The protection provided by the Sapphire quantum dot shell makes passivated nanoparticles particularly well suited to the demanding requirements of optoelectronic applications," said Dr. Qu.

In a poster presented last August at the 26th International Liquid Crystal Conference (ILCC) at Kent State University in Ohio, the company shared its finding on the use of air-stable quantum dots, co-extruding them with PMMA at over 200°C to obtain a functional quantum dot/polymer composite.

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