Toxicity of Indium Phosphide in Quantum Dots

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The electronics industry has been using indium phosphide (InP) to engineer advanced components such as quantum dots, due to a possible RoHS exemption of the compound. They were considered the perfect solution for creating cadmium-free quantum dots for commercial application in the display sector, resulting in multiple manufacturers laboring under the incorrect assumption that indium phosphide is not a toxic compound.

However, new data has shown that indium phosphide is as much as 10 times more toxic than cadmium (Cd), and the accepted occupational exposure limit (OEL) for the mineral indium is 1,500 times lower than lead (Pb).

What this means for quantum dot manufacturers will be explored in more detail within this article.

Research into Indium Phosphide Toxicity

Indium phosphide is a comparatively new semiconductor that was quickly adopted by the electronics sector after its discovery. Research into the fundamental chemical behavior of the compound was initially fairly weak, but multiple leading organizations have worked to characterize the material, and its potential toxicity, in greater detail.

Indium phosphide has been concluded to be a hazardous substance by the International Agency for Research on Cancer (IARC), REACH, and the Committee on Hazardous Substances (AGS) of the German Federal Ministry of Labour and Social Affairs (BMAS).

The IARC has classified indium phosphide as a group 2A substance, meaning that it is “probably carcinogenic to humans”. This conclusion was based on a study of increased occurrence of malignant neoplasms in rats and mice exposed to low levels of indium phosphide for short periods. REACH independently determined indium phosphide to be a carcinogenic, mutagenic, or reprotoxic (CMR) material.

The German AGS sets the OEL of substances. The OEL of indium phosphide is five times lower than for cadmium, and 100,000 times lower than for lead, representing an equal risk of lung cancer from exposure at these concentrations.

This information creates a vivid picture concerning the risks of using indium phosphide in an unregulated manner, and its use in the manufacture of quantum dots for commercial sale.

It presents a decisive argument that indium phosphide should be RoHS regulated to, at a minimum, the same degree as cadmium.

Alternative Quantum Dot Materials

Quantum dots produced by metal halide synthesis are both cadmium free and fully RoHS compliant, representing greatly reduced toxicity compared to indium phosphide. They contain lead and lead compounds, though within the 0.1% concentration levels sanctioned as safe for homogenous materials by RoHS.

Regardless of fears concerning lead poisoning, largely proliferated when it was used ubiquitously in construction and engineering, lead is still used in substantial quantities by the electronics sector. Most of today’s car batteries are based on lead-acid storage batteries which use extensive amounts of lead.

Lead concentration levels as low as 10 times below the accepted RoHS limit are the promised concentrations in metal halide quantum dot products. To compare these two quantities, if every television produced each year was equipped with halide perovskite quantum dot components, it would represent only a millionth of the annual volume of lead used for manufacturing lead-acid batteries.

Avantama Quantum Dots

Avantama is a world-leader in engineering material solutions for advanced electronics applications. Avantama supplies metal halide perovskite quantum dots of excellent stability and first-rate chromatic properties, compared with conventional cadmium selenide nanocrystals.

Avantama quantum dots epitomize the best energy saving and color performance quantum dots in the display sector, with lowered toxicity compared to all other chemical compounds. A RoHS regulation of indium phosphide will most likely be in place by 2019 or 2020 latest. No RoHS exemption can be granted for indium phosphide because with halide perovskite quantum dots there is a safe and better performing alternative commercially ready.

This information has been sourced, reviewed and adapted from materials provided by Avantama.

For more information on this source, please visit Avantama.

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