Disclaimer: this article contains some speculation but is reported to the best of my knowledge as of the date of publishing.
Quantum dots on LEDs have the promise to change the display and lighting industries by displacing current phosphors, but it’s no easy task. The concept is simple: Replace broad-emitting, bulky phosphors with efficient nano-sized QDs. The result: higher efficiency and better color for displays and lighting (see my blog last year about “On chip – the next big challenge for quantum dots” for more info). Unfortunately progress has been slow due to the high light flux and high temperature on an LED chip (two things that QDs really don’t like). Despite the challenges, the technology is receiving a lot of attention as it moves out of the lab and into commercial products. The big news right now… there has been a recent acquisition in this field, and announcement of the first ever QD on-chip product.
First ever QDs on-chip product launched by Lumileds
A few weeks ago in Nashville at the Department of Energy Solid State Lighting Workshop, a number of companies presented about their technology status, and outlook for the future of solid state lighting. I presented on a panel with LED and phosphor experts to discuss the potential for QDs to impact the lighting industry. Lumileds presented on their recent success using QDs on-chip to achieve high color rendering and improved efficacy in their Luxeon product line. They formally announced that Lumileds has launched lighting products using QDs integrated into the silicone encapsulant, a true QD on-chip product (Luxeon 3535L HE Plus). While this package only contains red QDs, it represents a big step forward for the industry as the first ever commercially available QD on-chip product. Congrats Lumileds!
The optical spectra from the Lumileds data sheet (above) shows multiple features which may indicate that there are more than 2 down-converters being used in conjunction with a blue LED. It is also possible that the unique QD absorption features cause non-traditional emission features from a broad phosphor like Ce:YAG. Regardless, the steep drop in emission from 650-750 nm (from the QD) means less wasted infrared light for improved color rendering and efficacy.
Presumably this package contains CdSe QDs similar to those used in their published report, which begs ever-present concern about cadmium. What is Lumileds’ plan around the RoHS cadmium ban? Where will this product be sold? Will customers adopt this technology knowing that it contains cadmium? Is there enough of an advantage over GE’s KSF phosphor to make it competitive? We have no choice but to wait and find out. It is worth noting that the Lumileds data sheet does state that the product is RoHS compliant and that they do not intentionally add cadmium to their products (technically it is CdSe I suppose… I’ll let the lawyers argue about that one).
Pacific Light Technologies acquired by Osram
The QDs that were originally used by Lumileds came from Pacific Light Technologies (PLT) who published their successes in the same journal as Lumileds. Which is why it’s particularly surprising that PLTs acquisition was not by Lumileds, but their competitor Osram. While I have been unable to get an official announcement from PLT or Osram, there have been numerous job postings by Osram for QD chemists in PLT’s hometown of Portland, OR (where until recently there were no Osram labs). In addition, many PLT employees have quietly transitioned to Osram employees based on their LinkedIn profiles.
To the best of my knowledge Osram has yet to release a product containing QDs, but considering this acquisition, I would expect one soon. QDs for on chip is what PLT is known for, and it’s not likely they are working on much else given their size and focused approach. It’s worth noting that Osram has been working with Nanoco since 2011 on Cd-free QD technology for on chip.
Amidst all of the excitement, there are many lingering questions. What will happen to to Lumileds supply chain now that their competitor Osram owns PLT? Who will be the next company to launch LEDs with QDs? Can anyone make a green QD on chip solution for displays? One thing is for sure, it’s an exciting time to be in the QD industry, I have a feeling we are just scratching the surface with many more innovations to come.
About the author: Peter is the owner and chief scientist at Palomaki Consulting, a firm specializing in helping companies solve big problems at the nanoscale. If you have questions about quantum dots or other nanomaterial technologies, don’t hesitate to reach out!
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