Technical / Research - Page 32

A senior VP at LGD recently declared in the IMID Display Business Forum in Korea that according to measurements done by the company, LCD screens emit 3.1 times more blue light than OLED screens. The measurements were done 120 cm away from TVs, 60 mm from monitors and 30 cm from smartphones (TVs are larger and emit more blue light than other types of screens).

Blue light is high energy visible light, widely acknowledged to bear harmful effects like discomfort to the eye and damage to the retina, as well as serve as a contributing factor to diseases such as cancer, diabetes, heart disease, obesity and insomnia. Children seem to have delicate retinas that are highly susceptible to the dangers of blue light.

In June 2014, Japan's Semiconductor Energy Laboratory (SEL), in collaboration with Nokia, unveiled new foldable OLED display prototypes - 5.9" 1280x720 (249 PPI) ones, which can be folded in two or in three (these were two different prototypes).

Last month in Japan SEL unveiled new prototypes. The new panels are bigger at 8.7" and offer a higher resolution (1920x1080, 254 PPI). The new panels are also touch-enabled. And they are still tri-folded like the ones shown in June.

Samsung Display introduced three new special displays modes enabled by AMOLED technology - an ultra power-saving mode (already used in some of their smartphones), color weakness mode and super dimming mode. These are great examples how OLED's emissive nature can be used for innovative solutions.

The color weakness mode can help people with color vision deficiency to distinguish red and green clearly - by inceasing (or decreasing) the brightness of the red and green subpixels.

In July eMagin announced they expect to receive a number of new R&D contracts, and now the company announced three new R&D project wins, worth a total of $6.8 million.

The first project is a $1.1 million contract over 15 months to further enhance the brightness of eMagin's ultra-high-brightness full-color microdisplay. The second project ($4.9 million, 30 months) and the third ($800,000 over 11 months) involved a new manufacturing technology that eMagin will detail in the near future.

Nippon Electric Glass (NEG) developed the world's thinnest glass plate (only 30 um thick). The G-Leaf glass can be used as a substrate for flexible OLED displays, and NEG demonstrated a flexible OLED that is only 90 um thick (sandwiched between two G-Leaf sheets).

NEG uses their "overflow method" technology to manufacture the new glass plates. Reportedly the glass feels like a plastic film and does not break even when crumpled (see photo below).

In the past two years, Evonik and the Holst Centre has been developing a new soluble Oxide-TFT material and a slot-die coating deposition process. Evonik is now commercializing the so-called iXsenic S material. In fact Evonik says that a key customer is introducing the product in a mass production display fab (it is unknown if this line produces OLED or LCD displays).

Evonik says that their new material offers a performance good enough for high-resolution OLED and LCD displays, and it can be deposited in a coating process which lowers production costs.

Microsoft research propose a new OLED power consumption technique (which they call FingerShadow) that uses local-dimming for screen areas covered by user fingers. Because OLED pixels only consume power when lit, this is a clever way to save power when people interactive with their smartphones or tablets.

According to Microsoft, they did a short study (10 users) and on average 11.14% of the screen is covered by fingers - which means FingerShadow can achieve a power saving of 5-22% (average 12.96%) with almost no overhead. Clever idea there Microsoft.

Researchers from the University of Tokyo developed a new technology to bond polyimide films to glass so it can easily be peeled off by applying heat. Polyimide is widely used today as a flexible OLED substrate, which is indeed produced on glass and then de-laminated at the end of the deposition process. This is an expensive process today (which requires a laser) with low yields.

The new bonding technology (which they call surface activated bonding) makes it easier to remove the polyimide film. In the new process an argon io beam is used to remove the oxide and adsorption films and flatten the surfaces. A 5-20 nm thick silicon layer is formed between the glass and the polyimide by ion beam sputtering. An iron adhesion layer (1 nm thick) is formed on the silicon to reinforce the bonding.

IDTechEx estimates that the barrier (encapsulation) layers for flexible electronics market will reach over $200 million by 2024. This will be driven mostly by flexible OLED displays for phones, tablets and wearables. Following is details regarding the different technologies adopted by Samsung, LG and others.

Samsung is using Vitex's multilayer thin-film encapsulation (TFE) using three layers (this is a new achievement, up until now they had to use at least 6 layers). While Samsung will still use this technology for its current and next-gen displays, Samsung is also considering other encapsulation deposition technologies, including Veeco's FAST-ALD and Universal Display's UniversalBarrier.

The Nikkei Asian Review reports that Athene, a Japanese semiconductor technology maker, developed a new shadow mask (or Fine Metal Mask, FMM) specifically for high precision OLED production. The new mask is stronger and more durable than any other mask on the market, which means it can be used to make higher resolution OLEDs.

Samsung AMOLED production

This new strong mask was achieved by adding nickel and iron materials to the standard metal mask. Athene's mask can withstand temperatures of up to 100 degrees Celsius without deformation, and the company says it can enable the production of OLED panels with pixel densities of over 500 PPI. Athene plans to setup a production line to make these new shadow masks and they will start delivering products to OLED makers in 2015.