Technical / Research - Page 35

Researchers from Seoul National University developed a new algorithm that remaps gray levels in image pixels so the image consumes less power on an OLED display. The researchers say that this algorithm can save about 10% while actually enhancing the contrast by 9%. The algorithm is linear and can be applied in real-time to high resolution videos.

The algorithms analysis the histogram of the image and changes the gray levels while maintaining the contrast. The key idea is that a large number of gray levels are never used in the images and these gray levels can be effectively exploited to reduce power consumption. To maintain the contrast, the algorithm takes into account the object size in the image to which each gray level is applied - so it does not perform changes to large objects.

Merck published an article on OLEDs in their Explorer Magazine, and in that article they reveal that AU Optronics is developing OLED ink-jet technologies with help from Merck.

AUO developed their own inkjet printer (with collaboration with suppliers), and they used it to develop a 14" printable OLED panel. Merck is working closely with AUO to supply them with soluble OLED materials. There's no word yet on how close this technology is for commercialization yet, and Merck did not reveal any details (or even a photo) of the 14" panel.

MBraun and Beneq announced that the two companies joined forces to provide complete turn-key systems for OLED R&D. The two companies will tailor R&D systems for customers that need research equipment int he areas of thin-film encapsulation and inert-gas glove box technologies.

OLED encapsulation is a hot topic, with several companies including Veeco, Beneq and Encapsulix developing and supplying ALD-based solutions. In October 2013 we published an interview with Beneq's technical sales Director.

Visionox developed a new RGB pixel arrangement for OLED technologies that allowed them to reach 570 PPI. The company refers to this new technology as Z-Type arrangement and it includes 3 sub-pixels (RGB) per pixel (unlike Samsung's Pentile displays). The sub-pixels are densely packed (the aperture ratio seems very high) in a way that does not suffer from jagged edges.

Visionox told me that they cannot yet say when such displays can be commercialized, as there are still manufacturing challenges to overcome. In the meanwhile the company applied for both Chinese and international patents.

Researchers from the University of Southern California developed a new software platform that can automatically rewrite web pages and web applications so that they consume less energy on OLED pages (i.e. reduce average pixel brightness). They report that using the software can achieve a 40% reduction in display power consumption.

The software, called Nyx, changes the colors of the web pages (or application) by choosing a new and efficient color scheme. The clever part is that the software chooses colors that are more efficient but that still maintain the color relationships between neighboring HTML elements as before.

Researchers from Kyushu University (led by Chihaya Adachi) developed a highly efficient blue OLED TADF (Thermally Activated Delayed Fluorescence) emitter that achieves almost 20% external quantum efficiency - similar to the best blue phosphorescent emitters.

TADF OLEDs are free from the heavy metals used in phosphorescent emitters and so they could be cheaper and better for the environment. The main problem with blue phosphorescent OLEDs is the short lifetime which still makes it impossible to use them in commercial applications. The new TADF blue OLEDs has about the same lifetime as the blue PHOLEDs, but researchers are hopeful that it will be easier to improve the lifetime of the TADF emitters.

Aixtron installed an R&D "cluster" at their clean-room that demonstrates the core processes used to produce organic semiconductors (deposition of OLEDs and flexible electronics). This new system offers industrial customers (and research partners) an integrated environment that shows off the company's core technologies.

The cluster includes several process modules and supports Gen-1 substrates (200x200 mm). The cluster is built around three OVPD systems embedded in an automated cluster environment and supplemented by various process modules and relevant infrastructure.

Konica Minolta developed the world's most efficient OLED lighting panel - at 131 lm/W. The panel's emitting area is 15 square centimeters. KM says that now OLEDs are actually more efficient than consumer LEDs, and this is a major step forward for OLED lighting. We do not know the lifetime or any other features of this panel.

KM's previous panel featured 103 lm/W and the company incorporated three new technologies in the new panel that enabled them to reach the record efficiency. First up is a new phosphorescent blue material that improved the internal quantum efficiency. In addition, KM also implemented a new light extraction technology and a new "organic layer construction technique", based on optical simulation.

A few weeks ago I posted about Plastic Logic's OTFT-based AMOLED demonstration. While the company's current demo is a simple display (monochrome white), it seems that Plastic Logic believes that OTFT technology is now reaching a performance level for adoption in AMOLED displays.

I discussed this with Mike Banach, Plastic Logic's Research Director. Mike (and the rest of the team at PL too, of course) says that organic semiconducting materials have reached a "tipping point" in electrical performance that makes them viable to drive flexible OLED displays. Couple this with the industrial and flexibility benefits of using solution-based organic materials makes it a compelling technology option for display makers looking to establish a position in the flexible display market.

The SID Display Week, the world's leading display industry showcase is scheduled for June, but the organizers already published the list of papers to be presented in this show. Hiding in this long list of technical achievements and research projects are some interesting new OLED developments. So here's some of the achievements to be announced during the show (at no particular order).

TCL's China Star Optoelectronics Technology (CSOT) managed to fabricate a 7" QVGA (320x240) flexible PMOLED display. The display uses a thin PEN substrate, processed at Gen-4.5. The company also proposes a design for a 14" QVGA PMOLED panel. CSOT also developed a 31" Full-HD AMOLED panel that uses a IGZO backplane. The 31" direct-emission panel was produced on a Gen-4.5 glass substrate using FMM.