Oxide TFT News
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.
A couple of weeks ago I reported that BOE showed a 55" 4K WRGB OLED TV at SID 2014. When I posted on this, I said that BOE probably used a panel supplied by LG Display (although it didn't make a lot of sense).
It turns out that I was wrong, and that panel was produced by BOE Display themselves, at the company's AMOLED pilot Gen-8.5 line in Hefei. The panel uses a bottom-emission white OLED with a color filter array (WRGB architecture). BOE also uses internal compensation technology. The 5 mm thick panel features a contrast ratio of over 100,000:1, a response time of 0.2 ms and a brightness of 120-400 nits.
In January 2014, Sharp unveiled 7" WXGA MEMS-based displays, promising to release them within six months. Last week during the SID conference, Sharp unveiled new prototypes, saying that they will start shipping those displays in Q4 2014 (yes, still half a year away).
Sharp's display use an IGZO backplane and MEMS technology developed by Pixtronix (a subsidiary of Qualcomm). The 7" 1280x800 panels offer a color depth of 24 bits and a 122% NTSC color gamut. Sharp says that this display is very power efficient - with full color it consumes less than half the power an an LCD panel. A monochrome display will use 1/10 of the power used by an LCD.
In 2013, Guangzhou New Vision Optoelectronics (New Vision) developed a flexible 4.8" AMOLED display using an Ln-IZO backplane and a polyimide substrate. New Vision now unveiled another flexible AMOLED prototype, this one using a PEN substrate. The company says that they expect flexible OLEDs to be commercialized in the near future.
The new full-color display is 5-inch in size with a thickness of only 0.1 mm and a weigh of less than 5 grams. The radius of curvature is up to 1 cm. New Vision says that PEN is preferable to Polyimide because it's cheaper, it doesn't require the complex preperation process required by PI and it enables transparent panels. The PEN substrate limits the production temperature to 180 C which created a major challenge for New Vision (to deposit the Oxide-TFT backplane at that temperature).
Researchers from UCLA developed an amorphous oxide semiconductor thin-film transistors (backplane) for LCD and OLED displays. The transistors were produced using a solution process and feature a specially-designed layer with ultra-high density and high electron mobility.
The researchers say that their new process does not require a clean room or expensive equipment, and so can enable a high-performance device that is simple and cheap to produce. The new device offers an electron mobility that is 10 to 20 times greater than a-Si TFTs. It is composed of indium gallium zinc oxide (IGZO) and indium tin zinc oxide, (ITZO).
Towards the end of 2013 it was reported that TCL plans to invest 24.4 billion yuan (just over $4 billion) to build a new 8.5-Gen TV fab in Shenzhen, owned by CSOT. This fab (called Huaxing Power Two) will have two lines, one for a-Si LCDs and one for Oxide-TFT (55" OLED TV and LCD TV, it seems) panels. The Oxide-TFT capacity will be 30,000 monthly substrates.
Now TCL announced that the company, together with CSOT and the Hubei Science & Technology Investment group will invest 16 billion yuan ($2.56 billion) and build a 6-Gen display fab that will also be used to produce AMOLED displays. It's a bit confusing, but it seems that CSOT aims to use both LTPS and Oxide-TFT for this production. The fab will be used to produce small/medium displays.
A few weeks ago I posted about Plastic Logic's OTFT-based AMOLED demonstration. While the company's current demo is a simple display (monochrome white), it seems that Plastic Logic believes that OTFT technology is now reaching a performance level for adoption in AMOLED displays.
I discussed this with Mike Banach, Plastic Logic's Research Director. Mike (and the rest of the team at PL too, of course) says that organic semiconducting materials have reached a "tipping point" in electrical performance that makes them viable to drive flexible OLED displays. Couple this with the industrial and flexibility benefits of using solution-based organic materials makes it a compelling technology option for display makers looking to establish a position in the flexible display market.