Oxide TFT - Page 6

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.

Chunghwa Picture Tubes (CPT) had some pretty interesting prototype OLED displays shown at the Touch Taiwan 2014 trade show last month. We do not have any information regarding how close are these prototypes to commercialization.

So first up is a flexible AMOLED display. This panel is 4.8" in size and 720x240 resolution (158 PPI). The company did not reveal any more technical details. The company also showed some simpler flexible PMOLED panels, demonstrating their sealing capabilities by immersing them under water (see image below).

Last month Sony, Japan Display, Panasonic and the INCJ formed a new OLED company called JOLED to focus on medium sized OLEDs. JOLED will be launched in January 2015 and has the potential to become a large OLED player.

A few days later, OLEDNet reported that JOLED is likely to choose small-molecules OLEDs, Oxide-TFT backplanes, Sony's Super Top Emission technology and an WRGB pixel architecture. Today I found Sony's original press release (a month late, actually), and there's some interesting information in there.

Last month Japan Display, Sony and Panasonic announced the formation of a new OLED company. JOLED, funded by the Innovation Network Corporation of Japan, will be established formally in January 2015, and will focus mainly on medium sized OLEDs for tablet applications.

JDI 5.2-inch FHD OLED prototype

One of the key questions surrounding JOLED is the technology choice. While Sony (and JDI, which is basing its OLED program on Sony's tech) is using small-molecule OLEDs and an evaporation process, Panasonic based its OLED development on Sumitomo's PLED materials and printing technologies.

TCL Group announced that it is going to raise 5.7 billion RMB ($926 million) in a private placement (there will be 10 different investors) to build CSOT's T2 8.5-Gen fab. This fab will use Oxide-TFT substrates and will produce both LCDs and AMOLEDs. The company filed information which specifically mentioned that this fab is important due for the future OLED technology.

CSOT's 8.5-Gen Oxide-TFT fab was discussed back in July 2013, but we do not have any information regarding its capacity and how CSOT plans to split it between LCD and AMOLED production. A $926 million investment is not very large for such a fab, so this is probably just the first production line. Earlier estimates for the cost of this fab were 24.4 billion RMB (just over $4 billion).

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).