When it comes to displays and lighting, consumers have a lot of choices to select from. The options shift, though, when different markets are considered. Smartphones, for example, are split between organic light emitting diodes (OLED) and LCDs. TVs have a wider range of options, with quantum dots (QD) making gains. Lighting has LEDs as a growing technology, while OLED and QD are trying to make some headway.
 
Quantum dots offer numerous advantages in its markets. It offers better colors gamut and is becoming more affordable. As a result, quantum dots have made significant gains in the TV and display segment.
 
“In TV, QDs are used as color converters in LCD panels (ie, the QD convert the light from the blue LED backlight unit into ultrapure red and green) ,” said Dr. Eric Virey, senior market and technology analyst – LED, Sapphire & Display for Yole Développement, a market research & strategy consulting company. “QD-LCD volumes could reach three million to four million in 2018. The market has so far been strongly dominated by Samsung, which targets the high end of the market with sets priced above $2000. Penetration could accelerate as credible players such as Visio are now coming with lower price sets that still deliver all the benefits of QDs.”
 
Dr. Virey said quantum dots are not used in smartphone applications. “This might change if the material stability increases sufficiently so that it could be coated directly on the LED chip, hence alleviating the need for a QD film which thickness (> 200 um) is a deterrent for mobile applications,” he added.
 
“If you buy a Samsung premium TV, you are getting a TV with quantum dot film,” said Brian Gally, head of products for Nanoco. “Gaming displays also use QD film. Clearly, the poster child is Samsung, which promotes QDs in premium TVs and gaming monitors, and Asus and Acer also use QDs in their gaming monitors. In China, TCL offers high-end TVs with quantum dots.”
 
“More than half of the premium TVs sold in the US over the last 12 months featured quantum dot technology from Nanosys,” said Russell Kempt, VP of sales and marketing for Nanosys. “As the costs of adopting quantum dots have come down it is now becoming possible for set-makers to waterfall the technology across their product lineups. As a result, we’re beginning to see quantum dot technology entering the mainstream market for TVs with several 65” TV products available below $1,500 by the end of this year.”
 
Lighting is also of interest to QD suppliers. On the quantum dot side, Nanoco is developing QD lighting for plants.
 
“We are pursuing QDs in lighting for plants,” said Gally. “You don’t need green for lights for growing plants indoors. You want to generate blue and red, using blue LEDs and red QD film to get the correct blue-red ratio, and can shift the red if needed to optimize the light for a particular plant.”
 
Printing and Quantum Dots
 
QD is an area where printing can play a role.
 
“On the QD side, there are two types of QD displays that could also benefit from printing deposition: The QD OLED described earlier where the patterned QD layers could also be deposited and patterned by printing; and electroluminescent QD displays (‘EL-QD’): in this design, the QD are excited directly by electrical charge rather than using color converters like in existing QD-LCD displays,” Dr. Virey said. “EL-QD would, in essence, behave like OLED and would be deposited similarly by printing techniques. Development of QL-QD material is still in its infancy and suffering from low efficiency and short lifetime. However, rapid progress makes them a credible option for the longer term. We expect EL-QD to appear on the market after printed OLED (i.e. beyond 2022.
 
The technology, however, will benefit from all the development made on OLED printing equipment and could potentially use the infrastructure and fabs set up for printed OLED.”
 
“In terms of printing with quantum dots, the first implementation of QD is film being placed in LCD displays,” said Gally. “The next step is to use QD as a color conversion mechanism. You could use QD to replace LCD color filters to do color conversion, and that can be inkjet printed. There is also talk of QD for micro-LEDs, which could also be inkjetted. Next-gen TV manufacturers are looking at these options. QDEL, with QD as the emitter, is still some years away, and these will be printed. There is a lot of work being done on QD inks. Quantum dots have a long future ahead in the display space, and really, quantum dots have only just begun.”
 
“Our quantum dots can be used in printed, flexible displays,” Kempt said. “It’s an area of research we are really excited about. In the future, printed, flexible quantum dot displays may really change how we think about our relationship with technology. We are thinking a lot about moving away from a device-centric world to a world of ‘Active Surfaces.’ These surfaces are interactive; they can display information or disappear into a home’s décor or even clothing. They need to be bright, power efficient, sensor-enabled and rugged. If we can get the cost of making a display down to $100 per square meter, which is basically the same cost as printing a high-resolution poster printing a T-shirt, then displays could be everywhere. That’s our vision and we believe that the quantum dot material is the only material that has the opportunity to achieve this.”