OLED (Organic Light Emitting Diodes) is a flat light emitting technology, made by placing a series of organic thin films (usually carbon based) between two conductors. When an electrical current is applied, light is emitted. OLEDs can be used to make displays and lighting, with possible applications that span TV sets, computer screens, mobile phones, decorative lighting and more. Since OLEDs emit light they do not require a backlight and so they are thinner than LCD displays, and are also more efficient, simpler to make and boast a better color contrast.

While OLED displays excel in color-contrast and efficiency compared to LCDs, they’ve also proven relatively hard to produce on a large scale. Current evaporation-based production techniques involve a lot of wasted material and risk of defects. OLEDs are also extremely sensitive to moisture and oxygen and therefore must be protected with a high performance encapsulating layer. All of these issues hinder OLEDs’ market takeover, but much work is put into resolving them.

OLED ink-jet printing

Current OLED producing methods rely on evaporation processes, in which the organic materials are deposited onto a glass sheet through a thin metal stencil, also known as a "shadow mask”. This process is problematic, as a significant amount of the material is wasted because it disperses all over the mask, in addition to inherent mask changes which expose the sheet to dust and compromise yields (OLEDs are by nature sensitive to contamination).

Inkjet OLED printing has the desirable ability to allow precision deposits without the use of a mask. It also produces less stray particles, thus boosting yields. These significant advantages make this technology interesting to many companies and virtually all OLED makers have active ink-jet printing development projects.

Inkjet methods form films by discharging the required amount of organic material onto large glass substrates in regular atmospheric conditions. This could be done, for example, by placing OLED pixels on glass or plastic using a portable platform and nozzles. Such methods have the potential to increase yields and lower prices, thus enabling OLED technology to take its deserving place in the market.



Unfortunately, OLED inkjet printing is not yet common, as printing OLED displays is a relatively challenging task for many reasons. A number of layers need to be deposited in pixels (the size of the pixels themselves is defined by the overall resolution the display will have). Being able to place the right number of drops of the active materials into the pixels is a challenge, in addition to developing a process in which the ink dries to deliver flat films of materials in the pixel.

Despite major progress, it is maintained that soluble OLED materials (required for inkjet printing) are less effective than evaporable ones. Ink-Jet printing is also not able to reach the same high densities of evaporation OLED production, which limits its applications for large-area production (TV panels) and not small mobile, VR and wearable OLEDs.

Ink Jet printing is still not used in any commercial OLED display production. But progress in past years have been rapid and some believe that initial OLED TV production using ink jet printing may begin in 1-2 years.

Latest OLED ink jet printing news

CSoT details its OLED ink-jet printing plans, collaborates with Kateeva, Sumitomo, Merck, DuPont and Tianma

Last month CSoT (TCL) announced plans to establish a 11-Gen LCD+OLED TV fab in Shenzhen, China. Details on the OLED part of that fab were not given, but now we have some updates following the company's investor day.

The new fab will use Oxide-TFT backplanes, and it turns out that the OLED part of the fab will also use the 11-Gen substrates (which may be cut for the actual OLED front plane deposition). Out of the entire capacity of 90,000 monthly substrates, the OLED line will use 20,000 substrates. The fab will start mass production in 2021.

BOE demonstrates its first inkjet-printed OLED prototype at SID 2018

China's largest display maker BOE Display has an active OLED ink-jet printing project, and according to reports the company is establishing an R&D production line (in Hefei) that uses Kateeva's inkjet deposition equipment.

At SID 2018, BOE demonstrated a printed OLED panel for the first time. Surprisingly this is a small mobile OLED display - a 5.5" FHD (400 PPI) flexible AMOLED. It is usually assumed that inkjet printing is limited to around 200 PPI, and so only useful to large area panels (such as TVs or monitors). JOLED's 21.6" 4K printed OLEDs have a PPI of 204, for example. In 2017 Korea-based Unijet's president said that Inkjet printing could reach up to 550 PPI in 2020 by using next-generation laser-droplet technologies.

Graphene for Displays and Lighting Market Report

Pixelligent raised $7.6 million, is working with Kateeva to adopt its materials for OLED inkjet printing

US-based high-index material maker Pixelligent Technologies announced it raised $7.6 million in a new funding round that will help the company to further drive its product commercialization and accelerate global customer adoption.

This round was led by the Abell Foundation, and included other Baltimore-based investors. This found also included strategic investments from Kateeva and Japan-based advanced material producer Tokyo Ohka Kogyo.

DSCC: the OLED material market will reach $2.56 billion in 2022

Display Supply Chain Consultants (DSCC) says that OLED material revenues grew 43% to reach $869 million in 2017. DSCC expects the OLED material market to grow at a 24% CAGR until 2022, when the market will reach $2.56 billion.

OLED material revenue by type (2016-2022, DSCC)

The small/medium display market accounts to about 59% of the total OLED material market, and this will continue until 2022. For the TV market, DSCC expects ink-jet printing to enable producers to make lower the material costs of OLED TV production, and OLED TV materials will grow at a rate of 23%, from $344 in 2017 to $963 million in 2022.

OLED Ink-jet printing market situation, early 2018

Many OLED producers believe that Ink-Jet printing of OLED emissive materials is the best way to achieve lower-cost OLED TV production, and to enable OLEDs to compete in the medium part of the TV market. Ink-Jet printing is an efficient process (less material waste compared to evaporation) and it can be very quick as well. The main drawbacks of inkjet are the limited resolution and the need for soluble emissive materials which are less efficient compared to evaporation ones.

A Kateeva OLED ink-jet printing system

These challenges are being overcome, and it seems that at least four groups (in Korea, Japan and China) are charging forward towards mass production of ink-jet printed OLEDs. Ink-jet printer makers and soluble material suppliers are also optimistic ink-jet printing commercialization will soon be here as the material performance gap is diminishing.

Here's Asus' 21.6" ink-jet printed OLED Monitor on video

Earlier this month Asus introduced a new OLED monitor, the 21.6" 3840x2160 (204 PPI) ProArt PQ22UC, which uses a ink-jet printed OLED panel produced by JOLED. The following video shows this new laptop which is said to have a remarkable image quality and a portable design:

Asus did not yet reveal the price of its first OLED monitor, but it did say it will ship by the spring of 2018. JOLED announced a few weeks ago that it started commercial production of 21.6" ink-jet printed 4K OLED panels. JOLED's production capacity is not large as the company is still using a pilot-scale line, but JOLED is seeking to raise $900 million to support its plan to start mass producing OLEDs in 2019.

JOLED supplies the 21.6" 4K OLEDs used by Asus in its new OLED monitor

Yesterday we posted on a new OLED monitor, the Asus ProArt PQ22UC with a 21.6" 3840x2160 (204 PPI) OLED panel. It turns out that this panel is produced by JOLED.

ASUS ProArt PQ22UC photo

This is very interesting news. JOLED indeed announced a few weeks ago that it started commercial production of 21.6" ink-jet printed 4K OLED panels, and it is great to see a product launched so quickly. JOLED's production capacity is not large, the company is still using a pilot-scale line, but it's likely that Asus is not expecting to sell many units of this high-end OLED monitor.

Denso may invest $450 million in JOLED to help it achieve OLED mass production

Following JOLED's announcement that it started commercial shipments of its 21.6" 4K OLED panels for use in medical monitors in its low-volume 4.5-Gen ink-jet printing production line, it was reported that the Japanese display maker is seeking to raise $900 million to support its plan to start mass producing OLEDs in 2019.

JOLED 4K prototype OLED Monitor (July 2017, Japan)

Reuters reports today that Denso Corp (an automobile parts producers) is considering a $440 million investment in JOLED. Earlier reports from Japan claimed the JOLED received funding commitments from Sony and Panasonic, with both Sumitomo Chemical (who supplies its P-OLED materials to JOLED) and Screen Holdings (who supplies its equipment to JOLED) are likely to take part in the financing round as well. Each of these four companies will invest between $45 to $90 million.

UniJet: Ink-jet printing could reach 550 PPI for small/medium OLED production in 2020

During an OLED display Seminar in Korea, UniJet's CEO Kim Seok-Soon said that new advances in Ink-Jet printing technologies could enable displays that are over 500 PPI - and so make printing a viable technology to produce small and medium-sized OLED panels.

UniJet 2017  LED-seminar slide, 550 PPI Inkjet printing

Kim says that current ink-jet printing processes can reach to to 150 or 200 PPI, which is good enough for TV production (enough for a 8K 55" panel in fact) but not good enough for small sized displays. However current laser-droplet measurement processes could enable discharge control of less than 0.1 μm and a volume accuracy of less than 0.1% - enough to reach 550 PPI. Kim estimates that such technologies could be ready for mass production lines by 2020.

Kyulux - Hyperfluoresence OLED emittersKyulux - Hyperfluoresence OLED emitters