Technical / Research - Page 30

Researchers from Japan (Chihaya Adachi of Kyushu University) and California have shown that OLED devices made with finely patterned structures are brighter and more efficient compared to regular OLEDs. The key finding in their research is that when the charge transport and recombination are confined to small nanoscale areas, the electroluminescent efficiency is increased because roll-off is suppressed.

The researchers say that such a structure (which are made using electron-beam lithography) may finally enable OLED devices to be bright enough and efficient enough to be used as laser sources. The researchers fabricated a small OLED device that supports charge density injection of 2.8 kA/cm² while maintaining 100 times higher luminescent efficiency than previously observed.

Finland's VTT Technical Research Centre developed a new technique to deposit patterned OLED lighting elements on flexible plastic films. This could enable a low-cost process technology to make flexible light emitting structured films - which they see used mostly in advertisement campaigns.

The new room-temperature deposition technology uses standard traditional gravure and screen printing - which means it may be possible to use in regular printing houses. The process makes OLED lighting stripes which are 0.2 mm thick and uses polymer based OLED emitters.

DuPont has been working on OLED materials and processes for a long time, but it's been a while since we heard any update. David Flattery, DuPont's OLED unit Director of Operations was kind enough to update us on the company's materials and OLED technologies.

Q: Dave - thanks for this interview. We know that DuPont is focusing on soluble OLED materials and processes. When do you see the OLED display industry starting to adopt such materials?

DuPont is focused on developing OLED materials for evaporation and soluble technologies, as well as working with our partners on our proprietary printing process.

Many in the industry believe that 2017 will be the year of mass production for printed OLED televisions, and while we cannot disclose the manufacturing plans for our partners, we have already seen one large manufacturer announce that they will pilot solution- processed OLED displays up to gen-8 in 2015.

Kateeva and Sumiomo Chemical announced a non-exclusive key partnership to pair Sumitomo's PLED materials to Kateeva's YieldJet OLED ink-jet printing platform. The two companies hope this collaboration will lead to adoption of P-OLED inkjet printing by OLED TV makers.

Kateeva and Sumitomo will cooperate to co-develop high-quality reference data for customers, which will be optmized to Kateeva's platform and Sumitomo's inks.

Researchers from UC Berkeley developed a pulse oximeter sensor that is made entirely from organic optoelectronics. The flexible oximeter can measure arterial oxygen saturation and heart rate, and performs as well as silicon-based pulse oximeters.

The sensor is made from red and green flexible OLED lighting devices and an organic photodiode (OPD). Unlike regular devices, this new organic sensor device is thin, flexible and (theoretically) cheap.

Royole, a startup established in the US in 2012, unveils their first prototype, a 0.01 mm thick (thin?) flexible AMOLED prototype (which they say is the thinnest ever). Here's a video showing the display in action:

The display is bendable, and has a bending radius of 1 mm. Samsung's recent flexible AMOLED prototypes has a radius of 5 mm - but these prototypes are closer to production units (the flexible OLED in the Galaxy Note Edge has a radius of 7 mm). Samsung's aim is to achieve a radius of 1 mm in production within two years.

According to OLEDNet, Seiko Epson developed a new OLED ink-jet printer head that can achieve a resolution of 360 PPI. This high-density print head uses two 180 PPI nozzles in 2 offset rows. The company managed to print prototype bottom-emitting and top-emitting OLED devices using this print head.

OLEDNet says that Seiko Epson is now aiming to develop a 600 PPI ink-jet printer head, by using two rows of 400 PPI nozzles.

Researchers from the Korean Inha University developed a new method to produce shadow masks that could lead to masks that have higher densities and are also more robust - leading to higher yields in OLED production. The team are going to transfer the technology to a company that will commercialize it.

Samsung AMOLED production

The researchers used an electrochemical processing technique to manufacture the new masks. This enables masks that are stronger (and thus fail less often) and still reach pixel densities of up to 500 PPI.

Samsung SDI and LG Chem are already developing bendable Li-Ion batteries, but Nokia is aiming higher: the company recently filed a patent for a graphene-based flexible transparent self-charging photon battery. This is still very early technology probably, and we're not sure if the company actually aims to commercialize it, but it's still exciting.

Nokia's battery design can regenerate itself immediately after discharge through continuous chemical reactions, without an external energy input - just from the humidity in the air). This could prove to be a truly energy autonomous device.

A UK-based star-up called R&D Core developed a new touch-display technology that is especially suited for flexible display. The company is collaborating with Plastic Logic to test the new technology.

SEL flexible touch-enabled OLED prototype

R&D Core's Digital Resistive Area Sensing (DRAS) is placed behind the display and responds to pressure. This has several advantages - it works with insulating materials (such as globes), it is less prone to breakage and it is more suitable for flexible displays. Last year we reported on similar technology from Peratech.