Technical / Research - Page 44

Panasonic Corporation developed a white OLED lighting panel that is the world's highest luminous efficiency - 114 lm/W for a light-emitting area of 1 cm². Panasonic also developed a larger panel (25 cm²) with 110 lm/W. The panels also feature long lifetime - over 100,000 hours (LT50) and a brightness of of 1,000 cd/m². The panel thickness was less than 2 mm.

Panasonic 114 lm/W OLED panel

To achieve this high efficiency, Panasonic focused on an all-phosphorescent design (with an optimal stacked layer design) and new light extraction technology. Panasonic used a Built-up Light Extraction Substrate (BLES) by optimizing the arrangement of the film, glass and air to suppress light confinement in the OLED. This enable them to achieve about 2.5 times improvement in the light extraction efficiency, which is about 50% in the new panels. Panasonic says that in older technology the light extraction efficiency stayed below 40%. Panasonic says they hold 30 patents in Japan and 17 overseas - all related for this new development.

A couple of months ago Toshiba developed a unique transparent OLED lighting device structure that emits most of the light (over 95%) in only one direction. Now at SID 2013 the company unveiled more information about the new structure, calling these panels "Transmissive Single-sided OLEDs".

Regular transparent OLEDs use transparent electrodes (usually made from ITO) for both sides of the panel. When the OLED is turned on, it emits light in both directions. Sometimes this poses problems - if you want to embed such panels in windows, for example, you don't want light pollution on the outside which just wastes electricity. In addition, when such OLED panels are turned on they are no longer transparent.

A few weeks ago we reported that AU Optronics developed a new 65" Oxide-TFT direct-emission OLED panel (the largest OLED panel ever made). Today at SID 2013 AUO discussed this new panel and unveiled the prototype:

AUO says that the panel is Full-HD in resolution, and it uses an "advanced" Oxide-TFT backplane. It was made in a Gen-6 production line which uses the largest Fine Metal Mask (FMM). AUO says that the uniformity of this panel is excellent. AUO also developed new pixel compensation driving technology which is employed in this panel. As can be expected from an OLED panel, AUO reports that their latest OLED features low power consumption, high picture quality, high contrast, high brightness, fast response time and free viewing angles.

Corning announced their new, second-generation Lotus XT glass for high performance displays (LCDs and OLEDs). The Lotus XT offers better dimensional stability and can withstand higher temperatures compared to the previous version.

The new glass features better total-pitch variation (the distance features move during panel processing). All this means that using the new glass shall increase production yields and result in more precise manufacturing. The new glass can be used as substrate for LTPS and Oxide-TFT backplanes.

Researchers from the Imperial College in London are researching the usage of Helicenes as emitter materials in OLED panels. Helicene based PLED emit circularly polarized light (they call these CP-OLEDs) and these may be useful for 3D OLEDs and other optical and photonics applications.

Helicenes are thermally-stable polycyclic aromatics with helically-shaped molecules. These molecules has unique structural, spectral, and optical features. The researchers found that when these molecules are used as emitter materials in OLED panels, they emit a light that is circularly polarized (not 100% though).

A few weeks ago we reported about Merck's new Taiwanese technology development center that is focused on OLEDs (but will also work on flexible displays, LED lighting and 3D displays). Merck held an official inauguration ceremony and they revealed some interesting details.

We already know that Merck OLED materials are "used commercially in many products on the market". But during the ceremony the company revealed that LG's 55" OLED TV, now on sale in Korea for $10,000, is using the company's materials.

The Holst Centre released a few nice videos, and I think they're worth a watch. First up is the one about their flexible OLED display research. Last year Holst and imec announced a new program to develop high resolution flexible OLED displays, with a focus on a mechanically flexible encapsulation film and TFT backplane, printed high-efficiency OLED and new materials and processes. The video below shows their first display (which was already unveiled last month):

In this new video you can see that the display is monochrome (red) and contains several defects.

The US Department of Energy (DoE) announced four new OLED lighting research grants as part of its Small Business Innovation Research (SBIR) program.

The first project, granted ($225,000) to Universal Display in collaboration with IDD Aerospace, aims to develop a low-energy shelf phosphorescent OLED light targeted at aircraft interiors. According to the DoE, IDD plans to commercialize this technology in 2015. Back in 2011, UDC showcased an all-phosphorescent, white OLED luminaire designed into an under-cabinet lighting system. This development was also funded by the DOE back in 2009. The warm-white OLED offer a power efficacy of 70 lm/W when operated at 190 lumens.

Researchers from the Fraunhofer COMEDD Institute in collaboration with Von Ardenne Anlagentechnik are developing new direct-emission OLED microdisplays. These new displays will be more efficient and cheaper than Fraunhofer's current microdisplays which use color filters.

Fraunhofer uses Von Ardenne's flash-mask-transfer-lithography (FMTL) technology. The FMTL-technology works with special transfer masks. Organic layers are locally deposited through the masks via thermal heat input and transferred to the microdisplay. This process needed a complete redesign to suit OLED deposition.

Plextronics has been awarded a $175,000 US DoE Phase 1 (Release 2) Small Business Innovation Research (SBIR) award for the design and development of low-cost processes of OLED lighting printed electrodes. Plextronics will partner with Electroninks (a startup that was spun-off from the University of Illinois to develop printable metal inks).

The new process will integrate Plextronics' conductive polymer inks (Plexcode HIL materials) with Electroninks printable metal inks. The printed metal lines will ensure high power efficiency and good light uniformity for large size OLED panels.