ALTHOUGH QUANTUM DOTS (QDS) WERE FIRST discovered at Bell Labs in the 1980s, their commercialization is accredited to Nanosys. The Milpitas, California-based company is the leading producer of QDs for displays. But Nanosys, founded in 2001, did not originally develop QD technology for display applications. In fact, it did not have any products in 2008, when Jason Hartlove took the helm as president and CEO. Hartlove, an electrical engineer with a successful product commercialization history, turned the company in a different direction. Every QD product since 2016—around 60 million devices—uses Nanosys’ technology, either under license or directly supplied by the company. Biotech entrepreneur Larry Bock co-founded Nanosys in 2001, along with Paul Alivisatos, now the president of the University of Chicago, and a team of scientists from MIT and Harvard. The field of nanotechnology still was in its infancy, and their mission was to find a way to bring this nascent technology to market, with a focus at first on solar cells and sensors. When Hartlove joined the company, it had an immense technology portfolio, including QDs, nanowires, and various other metal nanostructures. It also had government grants and venture capital to bring its vision to fruition. Yet, no marketable products were in the pipeline. “They had high-quality scientists, high-quality work, but were not extremely market- or problem-directed,” he said. “There was no orientation toward, ‘hey there's an unmet need in the world, let's see what can be done to address that.’” Hartlove has an eye for understanding customers’ needs and for identifying how products fit into the market. His background included co-inventing and commercializing the first optical mouse at Hewlett-Packard. At Agilent, he worked with Nokia and Erikkson on the first camera phone implementations in the 1990s. QD enhancement film Jason Hartlove holds up a sheet of QDEF as it rolls off of Nanosys’ pilot production line at the company's Silicon Valley headquarters (2015). Photo credit: Tekla Perry. Nanosys was experimenting with QDs for general illumination. But the semiconductor nanocrystals’ strength is as high-efficiency narrow-band emitters at any wavelength. The quantum confinement that sets the effective bandgap of the nanocrystals depends on their size, he said. They can be tailored to emit light at any visible wavelength depending on the starting bulk material and their size. This makes them perfect for displays that need narrow band red, green, and blue sources to achieve the highest color gamut, accuracy, and efficiency. At the time, however, QDs were expensive and unstable. They were core–shell particles made of a cadmium-selenide core and zinc selenide or a sulfide shell made in solution chemistry using dangerous precursors that made them hard to scale. It also was difficult using these methods to make high-quality particles consistently. Hartlove led Nanosys scientists to focus on improving the materials’ chemistry and production process to make large-scale batches of perfect core–shell particles. That led to the company's first product: a green wavelength illuminator for military cockpit head-up displays. To make the product rugged under flight conditions and to keep the QDs from being exposed to oxygen and moisture, a QD solution with extra chemicals added for stability had to be sealed in a hermetic sapphire chamber and then wrapped in tough titanium housing. All that engineering bore a cost that was impractical for consumer products. Plus, customers in the display industry did not want cadmium-based QDs because of lifecycle and recycling issues. To succeed, Hartlove knew they needed to engineer the materials into components that manufacturers could fit effortlessly into existing production lines and reduce or eliminate the presence of heavy metals. The Nanosys team worked tirelessly on the material chemistry to make QDs more stable, efficient, and consistent. They replaced the cadmium-selenide cores with indium-phosphide. “This was very difficult chemistry to get right, consistently and repetitively on scale,” Hartlove said. “This was just magical stuff. It was key to getting all the major brands that we have today using quantum dots.” While the materials improved, they were still not completely stable against oxygen and moisture. So the company's solution was to laminate them between dense, barrier-coated plastic films. Nanosys announced these QD enhancement films (QDEFs) at Display Week in 2011. By converting light from blue gallium nitride LEDs into red and green light at specific wavelengths, these films produced high-quality white light that made LED-backlit LCDs vivid and bright. The films could be scaled to any size, and device manufacturers could drop them into their production processes to make large TV screens, increasing color gamut by a factor of three. Nanosys’ QDEF technology made its way into the Amazon Kindle Fire in 2013 and the ASUS Zenbook in 2014, but the films were not cheap. They cost up to $300 per square meter, and Amazon paid about $3 for the small piece that went into the $99 Kindle Fire. Nanosys has come a long way since. By using improved shell layers, the company's engineers have made air-stable QDs that require no encapsulation. These new materials can be processed in open air at high temperatures. “With these, we're able to confine all the excited state energy in the particle,” Hartlove said. “This keeps the surface from becoming charged, which makes it non-reactive to its environment. What that enables now is for customers to implement even newer form factors for a reduced cost.” Red heavy-metal-free QDs A 70-liter vessel of red heavy-metal-free quantum dots illuminated by UV light as it is prepared for shipment at Nanosys’ headquarters in Silicon Valley. Photo credit: Nanosys. Last year, the company collaborated with China-based Nantong Changed New Material Co. to make a QD diffuser plate that converts blue miniLED backlight into white. This product won the 2022 Display Industry Awards Display Component of the Year award at Display Week. Electroluminescent nanoLED pixels A rainbow of electroluminescent nanoLED pixels made using Nanosys’ heavy-metal-free quantum dots. The pixels all are made with the same materials, and the size of the quantum dots determine the color. Photo credit: Nanosys. The QDs are mixed with a plastic powder and extruded into plate form. The plate is now in mass production for leading display manufacturers, such as TCL and Hisense. The technology will provide color and brightness enhancement in TVs that cost less than $500, which make up a two-thirds share of the consumer display market. Customers’ requests also have led to ever-changing chemistry. Nanosys has engineered QDs from proprietary semiconductor compounds that absorb blue light much more efficiently than indium phosphide. These are ideal for color conversion applications in self-emissive displays, where they were deposited directly on top of blue light emitters to convert the blue light into red and green. This requires patterning QD material on top of the tiny pixels in a layer only a few microns thick in order to absorb 100 percent of the blue light. “Most of the things people are working on in terms of future display technologies are emissive,” Hartlove said. These include displays in which blue light is emitted by OLEDs or microLEDs. “The advantage of integrating quantum dots into those architectures is to improve performance, solve manufacturing challenges, and reduce costs,” he said. “Those become the next frontier for us in terms of how we're going to use these materials. That presents different challenges.” Hartlove, ultimately, is most excited about the use of QDs as active emitters in displays. In such electroluminescent displays, electrons and holes are directly injected into a QD film to emit light. The company is working with several partners on the technology. At Display Week 2022, BOE Technology Group, one of Nanosys’ investors and partners, demonstrated the first 55-inch 8K active-matrix QD electroluminescent (QDEL) display. “It's a beautiful product,” Hartlove said. “The beauty is that it's all solution-printed. There is no evaporative process, no vacuum or high temperature required. This enables a completely new way of thinking about displays. But in terms of overall lifetime and readiness for manufacturing, we're still some years away.” Nanosys continues to cast its net wide. In May 2021, the company acquired glo, the leading maker of microLED displays. MicroLEDs are tremendously valuable in applications that require extremely high luminance and fine pixel size, such as contact lens displays and augmented reality headsets, Hartlove said. Making the 2-µm pixel-sized LEDs is difficult, especially for red emitters. That's because the charge carriers have very long lifetimes, so they get absorbed by defects, drastically reducing efficiency. Placing red QDs on blue microLEDs would provide a valuable red emitter to make high-efficiency red microLEDs. “The melding of these two technologies is going to be very important for the industry,” he said. Backed by top strategic and venture capital investors, Nanosys has made consistent advances that showcase the promise of QDs, leading to a skyrocketing demand for the material in displays. Samsung is one of Nanosys’ biggest strategic investors and R&D partner. At CES 2015, Samsung unveiled three QD-enhanced backlit LCD TVs developed in partnership with Nanosys. The QDs were made of cadmium-free materials, marking the first time heavy-metal-free QDs were used in any commercialized product. And in 2021, Samsung Display announced that it is investing more than $11 billion in a factory to mass-produce QD-OLED displays that combine QD's bright, rich, and pure color with OLED's incredible contrast and wide-viewing angles. Despite having the lion's share of the QD market, Nanosys remains a small company of about 100 employees. Critical to the company's success has been Hartlove's far-sightedness and an “amazing team” with an ability to deliver. “We've been able to uniquely bridge this interesting, very cool tech that came out of research laboratories into this marketplace,” he said. “We were able to clearly identify the dearth of low-cost, easy-to-implement RGB emitters, and to listen to customers and build a whole network to bring that technology to market. We make our own quantum dots, but also have dozens of people making optical films and manufacturing partners who make quantum dots for us. This whole ecosystem has really been built with an ear to customer's needs.” Prachi Patel is a Pittsburgh-based freelance journalist who writes about energy, materials science, nanotechnology, biotechnology, and computing.