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 is trying to make some headway.

OLEDs and quantum dots have some elements in common. In their own way, both offer better colors gamut and are becoming more affordable. Each also offers the potential for printing.

OLEDs in the Market

OLED has done particularly well in the smartphone space, with high-end Samsung phones using OLEDs and Apple adding OLED screens to some of its new iPhone models.

“We expect OLED to account for about 30% of smartphone shipments in 2018,” said Dr. Eric Virey, senior market and technology analyst – LED, Sapphire & Display for Yole Développement, a market research & strategy consulting company. “Besides Samsung and Apple, many other brands are now using OLED for their flagship phones (Xiaomi, Sony, LG, Google…). The leading supplier is Samsung Display, with more than 90% share in 2018. We expect OLED to capture >50% of the smartphone market by 2020.

“Today, the major limitation is capacity, but as new entrants such as LG Display in Korea and BOE, Tianma and others build and ramp up fabs, supply should not be an issue and price will decrease further,” he added.

For OLEDs, the TV market has been more of a challenge.

“For TV, success has been more modest. We expect about 2.5 million OLED TV to be sold in 2018, out of a total market of about 220 million units,” Dr. Virey said. “This number could grow to more than 9 million by 2022, still representing less than 5% of the market. However, while small in number of units, OLED is very successful in the high end of the TV market (TV > $2000). Penetration is limited by cost as well as capacity: while there is now a dozen OEMs offering OLED TVs (LG Electronics, Panasonic, Sony etc.), there is only one panel supplier, LG Display, which sells panels to all those TV brands. LG is expanding its OLED TV panel capacity in Korea with a generation 10.5 Fab and building a generation 8.5 Fab in China. Those should be operational within the next couple of years.”

Dr. Mike Hack, VP for Universal Display, said OLEDs have made major breakthroughs, notably in the cellphone display and TV markets.

“The one billionth OLED cell phone was shipped recently,” Dr. Hack said. “Samsung uses OLED technology for all of its Galaxy S series, and Apple just started using OLEDs in its iPhone in 2017.

OLED has more than 50% of the high-end smartphone market compared to LCD, the incumbent technology. In TV, LG Display’s sales are ramping up and is expected to ship close to 3 million units so far in 2018. The picture quality is really stunning, and prices have come down.”

Craig Bandes, president and CEO of Pixelligent Technologies, said that Pixelligent is going to have its first real number of significant commercial applications hitting the market next year, with one application that has already become commercial.

“For the last three to four years, we have been engaged with leading display technology companies, and these projects are coming to fruition,” Bandes added.

Pixelligent’s Bandes said that initially, OLED made inroads in mobile displays, and has also made gains in the TV segment.

“The Galaxy has shown tremendous improvement since Samsung first brought it out in 2010,” Bandes said. “Apple is now having its first OLED components coming into its technology play with the release of the iPhone X. You’ll see an increasing number of OLED devices entering the market in 2019.

“In the OLED TV segment, LG Display continues to dominate, while other companies are trying to come in,” added Bandes. “OLED TVs have excellent contrast, truer blacks and crisper images, and other companies will enter the OLED market. OLEDs offer a better contrast ratio than you can ever get with a quantum dot, while QDs have ultra-deep colors but are a very expensive material. TVs are a big market and consumers will be able to choose from these technologies.”

Quantum Dots

Quantum dots have made 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. Virey. “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.”

OLED Lighting

Meanwhile, OLED lighting has come a long way – but it also has a way to travel.

“OLED lighting is for the most part in niche applications, getting traction in automobiles, where it offers some very unique designs, and is being used by BMW and Audi for rear lighting,” Dr. Hack said. “LED lighting came onto the scene 10 years ago and the industry slowly adapted. The industry is still heavily focused on commercializing LED lighting. Since we are still in the early days of OLED lighting, volumes are still relatively low so the cost is still high. The cost needs to come down.

“Most traditional lighting technologies are based around a light bulb, a bright sort of hot spot, and you need a lampshade or a diffuser to avoid glare,” Dr. Hack added. “OLED lighting is a surface area source of lighting with no bright spots. It can be flexible and transparent.”

Bandes said the OLED lighting field is just starting.

“OLED lighting is where LED was 10 years ago, where the economics are pretty tough right now,” Bandes said. “You have two main players. LG Display has a Gen 5 line for making OLED panels for automotive and general lighting. In lighting, LG Display has around 90% of the market, with OLEDWorks starting to bring products to market. The beauty of OLED lighting is that it provides pure white, with no blue emitters that can cause eye fatigue and headaches. Improved economics are coming, and I believe OLED lighting will start to show growth by the middle of next year and really gain momentum in 2020.”

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 OLEDs and Quantum Dots

The idea that large TVs and displays could be printed is an attractive one for cost reasons, and leading companies are emphasizing this as one possibility. Founded out of Sony and Panasonic, JOLED, for example, recently raised 47 billion yen ($420 million) from its partners, including Sumitomo Chemical, Panasonic, DENSO Corporation, Toyota Tsusho and Screen Finetech Solutions.

The new capital will be raised on setting up mass production for OLEDs.

Dr. Virey said inkjet printing is a major area of development for TV applications. “All major panel makers have significant efforts in this direction,” he added. “Inkjet is already used routinely in OLED display manufacturing to deposit the organic layer that is part of the encapsulation necessary to protect the OLED emitters that are very sensitive to air and oxygen. Rapid progress is being made in depositing the OLED emitters themselves.”

Dr. Virey added that work is still needed in term of both the printing technologies and the materials. “The performance of the solution processable OLED materials required for inkjet printing is still falling behind that of the materials currently deposited by evaporation. Leading companies, however, are closing the gap rapidly,” he said. “Once both the materials and the printing technology are ready, it will still take some time to ramp up manufacturing as this equipment is quite different from those encountered in traditional display manufacturing fabs. We, therefore, don’t expect to see any significant volume of printed TVs before at least 2021-2022.”

Inkjet printing is already being used to produce OLEDs. “Our quantum dot technology can be printed. We’ve been working closely with Japan-based DIC to develop quantum dot inkjet printing inks for displays. These inks can be deployed today in LCD, microLED or OLED displays as a color conversion layer. We expect to see products based on this technology in the market soon,” Kempt said.

“We have reformulated our materials to be inkjet printable, and it is already commercial in one application,” said Bandes. “Not every layer is being inkjetted yet, but we are getting pretty close.”

Printing has long been a target for OLED manufacturers, and Universal Display has developed its own deposition technology that accomplishes this.

“Printing has been talked about as the holy grail of OLED TVs,” Dr. Hack said. “The current way of making OLEDs is through vacuum deposition. When you print in solution, generally the device performance has not been as good as devices made by vacuum deposition as you have to use solvents which can have impurities, which have to be driven off. UDC believes that printing will be important to make large area TVs, and we have developed our own process, OVJP (organic vapor jet printing), in which we can dry print OLEDs in the gas phase. We can get the benefits of printing and not need a mask, but there is no solvent solution. UDC is developing it internally and is engaged with the industry on this project.”

QD is another 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 microLEDs, 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.”

Flexible and Foldable Displays

One real opportunity for OLEDs is found in foldable, flexible displays for smartphones, and this appears to be on its way to the market. It has been challenging putting OLEDs on plastic, but it has been pretty much solved. In particular, developing a foldable, bendable form factor is a huge opportunity for display manufacturers and one where OLED can excel.

Darice Liu, director of investor relations and corporate communications at Universal Display, discussed the opportunities for foldable displays.

“The key thing that a lot of folks are excited about are foldable displays,” said Liu. “OLEDs consist of film layers. OLEDs are the only technology that allows you to have a bendable, rollable, foldable display. It is going to create a lot of excitement, and you’ll see continuous improvements in the technology. Once you remove the limitations of glass, there is a lot you can do with new designs and applications.”

“Samsung has announced that it will launch a foldable device next year that will be a phone that will fold out into a tablet. That will be a big breakthrough,” Dr. Hack said. “OLED on plastic will change the game in displays. A lot of things needed to be solved to get there. There have been technical challenges, with all sorts of flexible coatings and barrier films that need to be applied. A lot of work has been done in these fields. Encapsulation has been solved for first generation foldable displays. As a result, there will be a lot more design freedom.”