Display technology: OLEDs are getting brighter and are making inroads into more and more areas
At the Electronic Displays Conference (EDC) in Nuremberg, there were insights into the current display development. A lot is currently happening with OLEDs in particular. Samsung is fine-tuning its new QD-OLED technology for TVs and monitors, while LG wants to elicit more radiance from its RGB OLEDs for mobile devices.
Panel manufacturer LG Displays accommodates two OLED stacks in the panel. The double structure improves the light efficiency of the panel by one and a half to two times, also it is less prone to burn-in and more durable; LG promises up to four times the service life. However, such tandem OLEDs are also more expensive because significantly more organic material and additional manufacturing steps are required in production. LG Displays is so far the only manufacturer to use the tandem structure in series production for flexible OLED panels. Samsung also wants to use the technology in the future.
The two self-illuminating OLED layers noticeably increase the light efficiency in the tandem OLED.
(Image: DSCC)
mobile devices
Both panel manufacturers want to control the organic layers with LTPO transistors (Low Temperature Polycrystalline Oxide), i.e. a mixture of fast LTPS TFTs (Low Temperature PolySilicon) and current-proof IGZO TFTs with indium zinc oxide in the charge carrier channel. The hybrid OLEDs with tandem structure are encapsulated with a thin film instead of a cover glass. This should make them 20 percent thinner and lighter than previous OLED panels. The market research institute DSCC expects that Apple will use hybrid OLEDs in 2024 for two iPad models.
In hybrid OLED panels, the top layer consists of a thin film instead of cover glass. This makes the panel 20 percent thinner.
(Image: DSCC)
Although this would give tablets with OLED displays a significant boost, analysts believe that LCD technology will continue to dominate the tablet market. The situation is somewhat different with smartphones: While LCDs were still in 58 percent of all smartphones last year, by 2027 it will only be 47 percent; thanks to falling OLED prices, organic displays will then dominate the smartphone sector. Contrary to what one might assume, this is not due to foldable or even roll-out smartphones. These will only occupy a niche in 2027 with a 5 percent share.
OLED lovers will be happy about the forecasts for notebooks: From 2027, the organic displays should be in the majority of all folding computers. This is also thanks to the new OLED factories that had been started by then, which also produce the tandem structure mentioned above. According to DSCC, Apple will then also equip its MacBooks with OLED panels.
OLED technology will increasingly be found in tablets in the coming years. According to DSCC, OLEDs will even become the dominant technology in notebooks from 2027.
QD OLEDs
Meanwhile, Samsung Display is further developing its QD-OLED technology for televisions and monitors. So far, the quantum dots that convert the blue light into red and green are applied to a separate substrate over the blue-emitting organic layer. In the future, Samsung wants to apply the particles directly to the protective thin film of the OLED stack. That would increase the brightness by another 20 percent and reduce costs because the additional substrate and some production steps are no longer necessary.
In the future, Samsung wants to print the quantum dots directly on the encapsulation instead of on a separate color filter substrate. As a result, the displays could shine about 20 percent brighter with the same energy requirement.
(Image: DSCC)
In addition, Samsung intends to use blue phosphorescent emitters in the future. These are significantly more efficient than the fluorescent emitter layer used so far, and Samsung could save one or two blue layers in the panel as a result. Until now, however, the service life of phosphorescent emitters has been too short. Universal Display Corporation, the developer of the blue phosphors, is said to have overcome this problem.
price question
In further development, Samsung is focusing on costs and light output. The QD OLED panels are currently significantly more expensive than the WOLED panels from Korean competitor LG Display.
When it comes to micro LEDs, in which each diode forms an RGB subpixel, little is happening. DSCC expects Samsung to deliver fewer than 1000 micro LED TVs this year. The company had shown various new models at CES.
According to DSCC, Apple wants to introduce a smartwatch with micro-LEDs in the coming year (market launch planned for 2025). However, this will be more expensive than the previous top model, since the yield in production (yield of good panels) is low.
It looks a little better with LED displays for video walls, here you can find more and more of the self-illuminating screens. However, the diodes used in it are also significantly larger than in the TV. The problem with micro-LED technology: the costs scale with the resolution, the smaller, the more expensive. At the same time, the efficiency decreases with decreasing LED size. In addition, the control of the LED displays requires even more complex backplanes than with OLEDs – whose TFT control is already significantly more complicated and therefore more expensive than in the LCD. Added to this is the low yield and the costly error detection and repair of the LEDs.
monitors and TVs
Because micro-LED displays are still decidedly too expensive, OLEDs and LCDs with mini-LEDs in the backlight make up the consumer electronics market. When it comes to TVs, OLED technology accounts for the lion’s share in the high-end sector, while LCDs with locally dimmable mini-LEDs are clearly in the lead among monitors. Even if you can now find a handful of monitors with high-contrast organic displays, the technology is reserved for a few applications here, also for cost reasons.
In the coming years, more monitors will use a finely dimmable LED backlight. OLED technology hardly plays a major role here, the mass market remains with conventional LCDs.
(Image: DSCC)
Demand in China plummeted
The demand for TVs, monitors, notebooks and other mobile devices is suffering from the aftermath of the corona pandemic – while the display production for these products is flying high. The latter is due to the long planning and construction times required for display factories – a lead time of seven years is not unusual here.
In the LCD sector in particular, factories were planned in China around 2015 that are now supplying large quantities. However, the market situation in China has changed completely in the meantime: the slump during the pandemic was followed by reduced purchasing power, and people in China had less need for new, ever more expensive devices.
Sales fell between 2015 and today by 20 million TV sets and 200 million smartphones, reported Paul Gray from the market research institute Omdia. According to the OECD, confidence in the domestic market has dwindled since 2022 at the latest, with the first slumps becoming apparent in China at the beginning of the 2020 pandemic.
(uk)
