Technical / Research - Page 33

BASF opened a new R&D center for electronic materials at Sungkyunkwan University in Korea. The new center will focus on materials for next-generation display technologies - specifically OLED displays and flexible displays (OLEDs and e-paper displays).

The new center will support local researchers - and will provide internships and training programs. BASF hopes to team up with local small and medium companies for joint development and marketing.

Samsung first unveiled the wrappable YOUM prototype that you see below in January 2013 - a year and a half ago. While the company is already producing flexible OLEDs, and have adopted one in the Galaxy Round, they have yet to release a product with a display that curves around the edges.

A curved OLED prototype device (Samsung)

According to reports from Korea, Samsung has now begun trial-production of panels that can be wrapped around edges (i.e. with a smaller curvature radius). They are still facing some technical issues with the plastic substrate, so real mass production is not expected soon. But Samsung may release a "technology-demonstrator" product, a limited-volume device just to show off the technology (as they did with the Galaxy Round).

Researchers from the University of Michigan developed metal-free phosphorescent OLED emitters. The idea is that if the emitter molecules cannot vibrate, they cannot release energy and light and so more energy is converted into light. At first they tried creating a stiff lattice (crystalize the emitters) - this achieved 55% light conversion (better than the 25% of regular fluorescent OLEDs, but not as good as the 100% achieved by heavy metal doping).

But this method cannot be adopted for commercial OLEDs easily, and so the second method they tried is to tweaking the organic molecules so that they form structural bonds with a transparent polymer (they attach "like magnets"). This is an easier process, but it achieved only 24% efficiency - similar to a regular fluorescent OLEDs. But they are working on ways to improve this. The important point is that they demonstrated that increasing the intermolecular bonding strength could efficiently suppress the vibrational loss of the phosphorescent light.

eMagin says that they will receive a number of R&D contracts over the next 2 months. The company will share more information when the contracts are officially signed, but they did say that they expect to more than double the brightness of their already ultra-high-brightness (5,000 cd/m²) full-color OLED microdisplays.

These new contracts will significantly increase eMagin's R&D contract revenue beginning in Q3 2014.

Back in 2012, LG Display was awarded a project by the Korean government to develop 60" UHD flexible and transparent panels by 2017. Later in February 2014, LGD said it is still on target for this project, and that it will show 17" flexible panel prototypes by the end of 2014.

True to its word, today the company announced that it has developed 18" rollable OLEDs and also 18" transparent OLEDs. LG says that it has acquired the fundamental technologies required to lead the large-size flexible and transparent display market. These are the largest flexible and transparent OLEDs ever unveiled!

Update: It turns out that the researchers did not fabricate an OLED lighting panel, but a small monochrome (green) OLED device.

Researchers from Philips, Graphenea and the University of Cambridge developed a new graphene-based transparent electrode that outperforms ITO in OLED devices.

Graphene by itself is not a good electrode material because the concentration of the charge carriers is low - which means that you need to dope it with excess carriers - while leaving it flexible and transparent. To achieve that, the team used a metal oxide film (molybdenum trioxide, MoO₃) as an intermediate layer between the graphene and the OLED layers. The work was performed as part of the EU project GRAFOL, aimed at roll-to-roll mass production of graphene.

Researchers from the University of Iowa and New York University developed a method to convert magnetic storage data into optical transmission data. Basically this means that one can directly control OLEDs from magnetic-based storage.

It turns out that the magnetic field of the storage has enough energy to excite an OLED to produce photos. The researchers say that this method can be an optimal solution for plastic-based devices. I'm not sure I understand this completely, but it seems an interesting innovation on the road to cheap plastic-based computing devices.

According to a new report by Korea's ETNews, both Samsung Display and LG Display managed to achieve major breakthrough in their OLED production processes. These new achievements will raise the production yields of OLED TV and flexible OLEDs.

So first up is LG Display, who applied a co-planar TFT with a top-gate structure that enabled the Oxide-TFT layer to become less vulnerable to the etching process. This results in better yields. This design has not yet been applied to the mass production lines. But in the upcoming M2 production line, LGD will use ALD technology instead of the current 2-partition deposition technology. This will reduce costs and improve process time.

Researchers from the University of Michigan, trying to make OLED brighter but still efficient, discovered that a pyramid-shaped OLED lamp is more efficient than a flat panel shape. The idea is that the reflective OLEDs are emitting in the inside of the pyramid, and all the light comes out of the open base.

The surface emitting light on the inside is more than four times larger than the opening at the base of the pyramid, but the whole pyramid consumes about three times less electricity than trying to achieve the same brightness with a flat panel the size of the base. In addition, the researchers found out that this device achieves a better light distribution (the "halo" effect).

As we reported back in February, SEL and sharp unveiled a 13.3" 8K OLED prototype. This ultra high density (664 PPI!) display uses SEL's C-axis-aligned crystalline oxide semiconductor (CAAC-OS) backplane.

SEL's previous 13" CAAC-OS OLED prototype featured 326 PPI. But that lower-resolution panel was flexible. This new panel uses white OLEDs with color filters. SEL adopted micro cavities to narrow the wavelengths. The display features a 84% NTSC color gamut (rather low for an OLED). Each OLED pixel is driven by five transistors and one capacitor (5T+C) - there are almost 500 million pixel transistors in this display.