Technical / Research - Page 28

Researchers from Korea's Ulsan Institute of Technology announced that they have developed a new technique that can improve the efficiency of Iridium-doped phosphorescent emitters by more than 30 times.

The team explained that this dramatic increase in efficiency was achieved by a new method to synthesize molecules - which resulted in "stronger" molecules. More precisely, the researchers created an emitter molecule in which the two carborane units were thethered by an alkylene linker.

This is a guest post by SCM's business developer Fedor Goumans

To further improve the efficiency and life-time of organic light-emitting diodes (OLEDs), ultimately the properties of underlying materials need to be tweaked at the molecular level. In materials science, as in other fields, modeling has become a more wide-spread tool integrated with experiments for a holistic research & development approach.

In particular, high-throughput screening computational screening may considerably reduce experimental costs for synthesizing and testing new materials. At the molecular level there are a few properties that are important for OLED life-time and efficiency. A simplified set up for an OLED device is depicted in Figure 1. The charge mobility and light emission properties can be predicted with computational chemistry, as explained below.

Researchers from Germany's Goethe University discovered that graphene doped with boron atoms feature an intensive blue fluorescence - which means that this new material may prove to be useful in OLED devices.

The Boron doping changes the graphene in two ways. First of all, it shifts the fluorescence into the desirable blue spectral range. It also improve the capacity to transport electrons. The new material is reportedly not sensitive to oxygen and moisture, unlike most boron-containing graphenes.

ITRI and Orbotech signed an agreement to jointly develop solutions for flexible display production. In the first stage, ITRI will use Orbotech's inspection technology to identify production bottlenecks in flexible AMOLED processes.

ITRI says that they are confident that flexible devices are the future of the display industry, and that flexible OLEDs will bring next generation form factors such as foldable tablets and wearable devices.

FlexEnable and Chunghwa Picture Tube (CPT) demonstrate an OTFT full-color flexible AMOLED display manufactured by using FlexEnable's low-temperature process and CPT's RGB OLED technology.

The glass-free prototype display (which you can see above) is a full-color AMOLED that operates at 60Hz and is only 125 microns thick. This is a great achievement, but it's not clear whether CPT aims to commercialize such displays any time soon.

Back in 2013, Fujifilm and imec jointly developed a new process to deposit and pattern OLED materials using existing i-line photolithography equipment. The two companies have now demonstrated a full-color photoresist OLED. They say that this could lead to a new process that can be used to produce high-resolution large-area OLED displays in a cost-effective way.

In the new prototype, the two companies patterned red, green and blue OLED materials to create a subpixel pitch of 20 micrometer. The full device is 40x40 pixels and achieved a density of 640 PPI. As you can see in the image above, UV rays were used to confirm the result.

Kateeva and DuPont announced that they will co-develop solutions for ink-jet printed OLEDs - specifically they will optimize DuPont's soluble materials for Kateeva's inkjet systems. The two companies hope this collaboration will enable then to offer a simple and highly-effective OLED TV printing process.

This follows Kateeva's agreement with Sumiomo Chemical that aims to pair Sumitomo's PLED materials to Kateeva's YieldJet OLED ink-jet printing platform.

Researchers from AU Optronics developed an AMOLED display that uses four primary colors (Red, Green, Blue and Yellow). They say that this design is more efficient than an RGB panel by 16%. The AMOLED panel is 4.65" 720p (317 PPI).

RGBY has been used by Sharp for their Quattron LCD displays (Aquos TVs) for a long time. Sharp says that adding another color increases the range of displayable colors (although the content itself does not provide the yellow color information, which means the TVs need to use software processes which results in less accurate colors).

Researchers from Japan's Semiconductor Energy Laboratory (SEL) and Advanced Film Device developed a 81-inch 8Kx4K OLED display that is built from 36 13.5" flexible OLED panels that have transparent edges on two adjacent sides.

The transparent edges enabled the researchers to connect the tiles seamlessly - to create the world's largest OLED display ever developed.

Next week at SID, Novaled will report on a new Vertical organic field-effect transistors (V-OFETs) that can be used to drive high-brightness AMOLED displays. Novaled says that the new backplane can be deposited on plastic backplanes, and it allows a 4X brightness enhancement compared to reference AMOLEDs.

Vertical-OETs has been first reported in 2011 by the University of Florida. That particular research used carbon-nanotube based backplanes, and it was spun-off to form a company called nVerPix which is commercializing the technology.