a-Si - Page 3

Hitachi unveiled a new 4.5" a-Si based IPS LCD display with 329ppi (720x1280). The company says that using amorphous silicon instead of an LTPS backplane means that the new display is cheaper then their previous IPS displays - with only a slight drop in performance (a lower contrast ratio).

Last month we heard that Hitachi, Sony and Toshiba signed an agreement to merge their small/medium display business. The new business venture will invest in OLED R&D and according to the companies, they consider OLED to be the core technology for next-gen small/medium displays. We do not know if Hitachi's new technology is relevant for OLEDs as well.

HP has developed a new method to produce large AMOLED panels, based on roll-to-roll manufacturing. They say that one of the biggest challenges to make flexible OLEDs is the alignment on large area flexible substrates. The new solution uses self-aligned imprint lithography (SAIL) to laminate a well-defined micro OLED (µOLED) frontplane unto a flexible active matrix amorphous silicon TFT backplane.

SAIL process flow

HP says they already built a proof-of-concept AMOLED device - which contains a flexible µOLED frontplane with OLED sizes of 50 µm on PET and active matrix backplane on polyimide with pixel pitches of 1 mm. The company claims that the new method will enable large area OLEDs at a very low cost.

There are reports that RiTdisplay started to mass produce 3.5" 320x480 AMOLEDs on a-Si backplanes, and the company was already contracted to provide the displays to several smartphone makers. a-Si backplane AMOLEDs will be cheaper and easier to produce than LTPS ones (which is the most common technology for AMOLEDs and next-gen LCDs such as Apple's Retina displays) as they can use existing a-Si equipment used to fabricate LCD displays.

Canada's Ignis Innovation provided the compensation technology and driver IC (which is made by Himax). These are the same panels unveiled at SID last month. The actual backplane was developed with an undisclosed display-panel maker partner in Taiwan.

Update: we learned that RiTDisplay have started to mass produce those AMOLEDs and have already found some smartphone clients.

IGNIS Innovation, unveiled a new 3.47" 320x480 AMOLED made on an amorphous silicon backplane (a-Si). The new display uses INGIS' new AdMo compensation technology and is made by RiTdisplay.

Today all AMOLEDs are made on LTPS backplanes. Ignis' solution uses a-Si which is cheaper but has stability issues. Ignis says that their new AdMo technology eliminates those issues - and makes the a-Si made AMOLED equivalent in performance to LTPS AMOLEDs. Ignis says that "This opens the door for RiTdisplay and other manufacturers to make state-of-the-art AMOLED displays using existing amorphous silicon equipment" - but they haven't announced when and if RiTDisplay (or other companies) plan to start using the technology.

Ortus Technology is developing a 6.5" OLED display, driven by a-Si TFT. The panel features 960x540 resolution (QHD) at 169ppi. The panel uses Ortus' own HAST (Hyper Amorphous Silicon TFT) technology, which offers ultra-high resolution, low-resistance fine wiring, narrow pitch COG bonding and high quality optic design.

Ortus Technology was established in April 2010 in Japan by Casio and Toppan Printing to work on small and medium displays. The company is focusing on LCDs, but also has an active OLED program.

Universal Display announced that they delivered eight wrist-mounted OLED displays to the US Army. Those 4.3" QVGA full-color displays are based on UDC's phosphorescent OLED materials and are built on thin flexible metal foil. The backplane is an amorphous-Silicon (a-Si) TFT, fabricated by LG Display. The displays were designed by L-3 Display systems and "offer various advanced communications features, all integrated into a thin and rugged housing that comfortably fits around a soldier’s wrist".

These prototype were built as part of a US Department of Defense (DOD) funded program.

Sony plans to sell an LCD plant that makes small-sized panels to Kyocera. Sony are moving away from LTPS (low-temperature polysilicon) and into a-Si (amorphous silicon) - they have just completed a deal to buy Seiko-Epson's small-size LCD operations that use the latter technology.

This is an interesting move by Sony, and might have implications on their OLED program, which shares some of the manufacturing process of LTPS LCDs.

Universal Display (FDC) and the Flexible Display Center (FDC) at Arizona State University announced that they have strengthened their collaboration to extend to the joint fabrication of prototype active-matrix PHOLEDs on flexible plastic substrates for the U.S. Department of Army. In addition, Universal Display announced that the company has been awarded a $650,000 U.S. Army Small Business Innovation Research (SBIR) Phase II Enhancement contract to support this work.

UDC and the FDC believe that the enhanced relationship will accelerate the demonstration of the flexible AMOLEDs. Earlier in 2009, they have already demonstrated a 4.1" monochrome QVGA PHOLED display.

As part of this strategic relationship, Universal Display and the FDC will work to demonstrate flexible OLED display prototypes with enhanced performance for the U.S. Army. The FDC will fabricate a-Si:H thin-film transistor (TFT) arrays on flexible plastic substrates using their low-temperature backplane and proprietary bond-debond manufacturing technologies. Universal Display will then use its UniversalPHOLED materials and technology to build full-color AMOLED displays

For prototypes to be delivered under the U.S. Army SBIR Phase II Enhancement Program, Universal Display will also use its proprietary encapsulation film technology to create permeation barriers on the substrate and on top of the OLED to prevent harmful moisture and oxygen from reaching the OLED device.

IGNIS Innovation, in partnership with Kodak and Prime View International (PVI), has developed a 5" segment of a 32" OLED HDTV AMOLED display, using industry standard amorphous silicon thin film transistors (TFT). The prototype uses IGNIS' MaxLIfe solution, which compensates separately for both the TFT and LED degradation using only an electrical feedback - an industry first. This technology does not use any optical sensors which are unreliable.

IGNIS reports 20 years lifetime (when watching 12 hours a day), there is no burn-in images (the MaxLife technology keeps differential aging to 3% or less). The prototype was built using an amorphous silicon backplane from PVI using their standard a-Si LCD mass production process while the frontplane uses Kodak's long life and low power RGBW technology that delivers a vivid and outstanding viewing experience. They say that this combination provides the first reliable, low ost and scalable architecture.

IGNIS has also shown a 2.2" QVGA (181ppi) display module, using their AdMo (Advanced Mobile) compensation platform. They report over 50,000hrs lifetime (in house testing), large temperature range (-30c to 80c), suitable for automotive applications. The sophisticated compensation technology is built entirely in-pixel, meaning low-cost driver ICs are used, lending itself to a simple ‘drop-in’ display that is easily swappable into devices using legacy LCDs. The AdMo prototype use an amorphous silicon backplane, the standard TFT of the LCD industry that has traditionally been regarded as unusable for AMOLED displays. However, through its patented technology IGNIS is able compensate for the low mobility and in-stabilities of amorphous silicon, and as a result, for no additional capital investment costs, enables the manufacture of AMOLED backplanes at existing TFT plants.

Universal Display Corporation has been awarded a $334,000 extension to a US army Small-Business-Innovation-Research (SBIR) phase III contract. UDC will continue to work on their flexible OLED display technology, and will deliver new prototype flexible displays built on metal foil (using amorphhous-silicon backplanes). The new displays will also be encased in new and thinner housing (the old ones were pretty bulky, as can be seen in the photo below).

UDC is working on this together with LG Display and L-3 display systems. They will focus on the design and performance of the OLED displays. The technology is being evaluation by the US Department of Defense for military applications such as a wrist-mounted display for soldiers.