QD III.5
One point that we feel obligated to make concerning quantum dots is safety. The highest efficiency quantum dots are based on Cadmium Selenide. Cadmium is a metal similar to zinc, however it is extremely toxic to humans and the environment, with indications that cadmium mining operations going back to pre-WW II had contaminated water sources, leading to health problems for local populations. It is one of only 6 materials banned by RoHS (EU Restriction of Hazardous Substances) and is considered a carcinogen by the International Agency for Research on Cancer. There are alternatives to using Cadmium in quantum dots, with Indium and Zinc among the alternatives, although they do not have the same characteristics.
While both Cadmium based and Cadmium free QDs are produced, we found it unusual that there was a very significant disparity between where each type of QD is used. According to the largest supplier of QDs globally, Cadmium free quantum dots are used in almost all display products produced by non-Chinese display producers, while Chinese display products seem to use Cadmium based QDs. There is a cost to using Cadmium free QDs, as they tend to be more expensive and less efficient, but are free of toxic materials, so one might look at the trade-off between the development and use of Cadmium free QDs as one that has slowed the overall development of QDs over time. That said, we would rather see the development of Cadmium free QDs as a global standard than a bifurcated development scenario even if it extends the developmental timeline.
While both Cadmium based and Cadmium free QDs are produced, we found it unusual that there was a very significant disparity between where each type of QD is used. According to the largest supplier of QDs globally, Cadmium free quantum dots are used in almost all display products produced by non-Chinese display producers, while Chinese display products seem to use Cadmium based QDs. There is a cost to using Cadmium free QDs, as they tend to be more expensive and less efficient, but are free of toxic materials, so one might look at the trade-off between the development and use of Cadmium free QDs as one that has slowed the overall development of QDs over time. That said, we would rather see the development of Cadmium free QDs as a global standard than a bifurcated development scenario even if it extends the developmental timeline.
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