Polyimide - Page 3

China's Guangzhou New Vision has been developing flexible AMOLED displays for a long time, and the company now unveiled its latest prototype. This 0.01-thick panel use a Polyimide substrate, an Oxide-TFT backplane and an RGB (direct emission) frontplane. The curvature radius is 4.5 mm.

New Vision's 2014 flexible AMOLED prototype actually used a PEN substrate - and it's interesting to see the coming moving back to Polyimide. Back in 2014 New Vision said that the flexible OLEDs will be commercialized "in the near future".

Samsung hosted an investors forum in NY a few days ago, and it is reported that much of Samsung's focus was on OLED technologies. As we already reported, Samsung Electronics announced that flexible OLED is one of its 3 areas of future growth (especially as they struggle to increase high-end mobile phone sales), and during the conference the company revealed some interesting information and prototypes.

Foldable OLED concept (2013)

So first up were two new foldable OLED prototypes - a 5.5" (WQXGA, 2048x1526, 464 PPI) panel that folds in half and a 10" tri-foldable AMOLED (Full-HD, 218 PPI).

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.

Taiwan's ITRI institute demonstrated several new AMOLED prototypes at Touch Taiwan 2014. First up, is Taiwan's first foldable AMOLED, a 6" full-color panel that can be folded inwards over 10,000 times.

The 6" panel can be folded to a radius of 7.5 mm. The whole panel is just 0.1 mm thick and it was developed with ITRI's own FlexUPD technology which can be used to turn an existing OLED glass line to produce polyimide-based flexible panels.

Back in 2012, LG Display was awarded a project by the Korean government to develop 60" UHD flexible and transparent panels by 2017. Later in February 2014, LGD said it is still on target for this project, and that it will show 17" flexible panel prototypes by the end of 2014.

True to its word, today the company announced that it has developed 18" rollable OLEDs and also 18" transparent OLEDs. LG says that it has acquired the fundamental technologies required to lead the large-size flexible and transparent display market. These are the largest flexible and transparent OLEDs ever unveiled!

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).

DuPont developed new screen-printable nano-silver conductor ink that can be used to make grids and bus lines for OLED lighting panels. DuPont says that these materials are less expensive compared to materials currently used for such panels, and they offer a simpler manufacturing process.

DuPont estimates that these new inks will be commercially available next year. The inks provide extremely high conductivity and excellent adhesion even after substrate cleaning steps. They can be used on glass and flexible polymer substrates such as DuPont's own Kapton polyimide films and polyethylene naphthalate (PEN).

The SID Display Week, the world's leading display industry showcase is scheduled for June, but the organizers already published the list of papers to be presented in this show. Hiding in this long list of technical achievements and research projects are some interesting new OLED developments. So here's some of the achievements to be announced during the show (at no particular order).

TCL's China Star Optoelectronics Technology (CSOT) managed to fabricate a 7" QVGA (320x240) flexible PMOLED display. The display uses a thin PEN substrate, processed at Gen-4.5. The company also proposes a design for a 14" QVGA PMOLED panel. CSOT also developed a 31" Full-HD AMOLED panel that uses a IGZO backplane. The 31" direct-emission panel was produced on a Gen-4.5 glass substrate using FMM.

LG Display posted a very interesting article explaining their flexible OLEDs, and giving some predictions (based on IHS DisplayBank estimates) about the flexible OLED market. A couple of months ago LG already stated that they see a very bright future for flexible OLEDs and they intend to take the lead in this emerging display market.

So first of all, LGD explains the structure of their flexible OLED panel (see below). It is based on a plastic (polyimide) substrate as we already know, and LG gives some more information about their Face Seal method which was discussed before but with very little details.

According to ETNews, during CES Samsung Display has been privately showing a new foldable display prototype. SDC continues to develop their foldable OLEDs, and they are still only track to release the first foldable mobile phone in 2015.

SDC Foldable OLED concept, 2013

According to the report, the prototype panel was 5.68" in size, it uses a polyimide (plastic) substrate and it includes a touch panel. The touch panel uses metal-mesh electrodes instead of ITO (which is brittle and cannot be used in foldable displays).