Quantum Dots and the Toxicity of Indium Phosphide

Due to a speculative RoHS exemption, the electronics industry has been using indium phosphide (InP) to engineer advanced components such as quantum dots. They were considered the ideal solution for generating cadmium-free quantum dots for commercial application in the display sector. This resulted in numerous manufacturers laboring under the false assumption that indium phosphide is a non-toxic compound.

In fact, new data has revealed 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).

This blog post will explore the toxicity of indium phosphide, and what that means for quantum dot manufacture in more detail.

Indium Phosphide: Research into Toxicity

Indium phosphide is a relatively-new semiconductor that was rapidly adopted into the electronics sector following its discovery. Research into the inherent chemical behavior of the material was initially thin on the ground, but several leading organizations have worked to characterize the material and its potential toxicity in greater detail.

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) have each concluded that indium phosphide is a hazardous substance.

The IARC has classified indium phosphide as a group 2A substance, which refers to materials that are “probably carcinogenic to humans”. This decision was drawn from a study of increased incidences of malignant neoplasms in rats and mice that were exposed to low levels of indium phosphide for short periods. REACH separately regulated indium phosphide as a carcinogenic, mutagenic, or reprotoxic (CMR) material.

The German AGS sets the OEL of substances. Surprisingly, the OEL is substantially lower for indium than for lead or cadmium. This required concentration of indium in the air to represent a certain risk of lung cancer was 5 times less than that of cadmium, and 100,000 times lower than lead.

These data create a vivid picture regarding the risks of indium phosphide and the unregulated use of the compound for manufacturing products such as InP quantum dots at commercial scales. It presents a conclusive argument that indium phosphide should be RoHS regulated to at least the same degree as cadmium.

Alternative Quantum Dot Materials

Quantum dots based on metal halide synthesis are both cadmium-free and fully-RoHS compliant, representing significantly reduced toxicity compared to indium phosphide. These nanomaterials contain lead and lead compounds within the 0.1% concentration levels sanctioned as safe for homogenous materials by RoHS.

Despite fears regarding lead poisoning, which were largely propagated when the mineral was used ubiquitously in construction and engineering, lead is still used in significant volumes in the electronics sector. Safe concentrations of lead have been used to manufacture all rechargeable lead-acid car batteries, for example. Metal halide quantum dot products are intended to contain lead at concentration levels as low as 10 times below the accepted RoHS limit. To put that into perspective on the commercial scale, if every television produced annually was equipped with halide perovskite quantum dot components, it would represent a millionth of the annual volume of lead required for manufacturing lead-acid batteries.

Quantum Dots with Avantama

Avantama is a world-leader in engineering material solutions for advanced electronics applications. We supply metal halide perovskite quantum dots of outstanding stability and superior chromatic properties compared to established cadmium selenide nanocrystals.

Our quantum dots represent the best energy saving, color performance, and significantly reduced toxicity compared to all other chemical compounds for quantum dots in the display sector. Indium phosphide is currently available on a RoHS exemption that is reserved for industrially-critical materials for which there is no suitable alternative. This is no longer true.

Contact us for any more information about our metal halide perovskite quantum dots.