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 are used to make displays and lighting panels. OLEDs today are widely used in TVs, smartphones, tablets, laptops and wearables.
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.
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.
For many years, companies all over the world invested heavily in inkjet printing processes for OLED displays, but the process is not yet common, as printing OLED displays is a relatively challenging task, and soluble OLED materials 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.
Printed OLED panels on the market
One area in which inkjet printing is common in the OLED production process is the encapsulation layer deposition. Almost all OLEDs that adopt TFE encapsulation use inkjet printing to deposit the organic elements.
LG 32EP950 OLED monitor (31" 4K printed OLED panel by JOLED)
For actual OLED emitter layers deposition, currently the only company that commercially uses ink-jet printing is Japan's JOLED, who in 2021 started printing OLED display panels in its 5.5-Gen production line in Nomi, Ishikawa Prefecture, Japan.
The latest OLED ink jet news:
In 2020 Samsung decided to use inkjet printers made by Korea's Semes, in its QD-OLED production lines. This created a major problem for Kateeva which hoped to win that account, which resulted in massive layoffs including some of its executives. These inkjet printers are used to deposit the QD layer in Samsung's QD-OLED panels.
According to new reports from Korea, Samsung has decided to change course, and rely on Kateeva's inkjet printers in its 2nd QD-OLED production line (the SDC 98.5-Gen Q-2). The reports suggests that the Semes printers do not perform as well as Samsung hopes, and these also cost more than Kateeva's printers (but Semes is affiliated with Samsung, which helped it to get the orders).
According to reports from Korea, Unijet has supplied China-based Sidtek with inkjet printing systems, used for thin-film encapsulation (TFE) deposition of OLED microdisplays. This is Unijet's first sell of a commercial TFE printing system.
Sidtek, established in 2016, is now producing 0.39" XGA OLED microdisplays, which are available on the OLED marketplace. Sidtek's 0.39" display is available in a color version (1,000 nits) or a monochrome one.
Yesterday we reported that during its DTC 2021 conference, TCL demonstrated a 65" inkjet-printed 8K OLED panel co-developed by TCL's CSoT and JOLED. During the conference, the company also unveiled another panel a rollable OLED.
This is a 14" inkjet printed OLED panel, produced using an inkjet printing process. TCL says that it has a rolling radius of
According to a report from China, TCL demonstrated 65" 8K OLED panel, produced using an inkjet printing process. This display was co-developed by TCL's CSoT and JOLED.
Last year it was reported that TCL's CSoT is building a $6.8 billion 8.5-Gen inkjet printing line in Guangzhou (the T8 line), with production expected to begin in 2023.
Notion Systems is a leading supplier of industrial ink jet printing systems. The n.jet inkjet platform from Notion Systems is used to produce printed circuit boards, OLED & QLED displays, sensors and high-quality 3D parts.
We present the following interview with the Company's CEO and founder, Dr. Michael Doran.
Q: Hello Michael. Can you detail notion systems' offering for the OLED industry? We understand you offer R&D and production systems, for both RBG printing and TFE printing.
Notion Systems offers a system platform called n.jet display series that prints functional layers at various steps of display production and for a range of display technologies. These include rigid, flexible, OLED, QLED and micro displays. The platform meets the most stringent requirements for process environment and process stability.
The National Center for Flexible Electronics (FlexE) was established in 2014 as a Centre of Excellence at the Indian Institute of Technology (IIT) in Kanpur. The vision of the center is to "catalyse the development of domestic industry in the field of large area flexible electronics".
The FlexE center has some interesting OLED projects, and we recently had a discussion with researchers from the center to learn more about the OLED R&D activities.
Inkjet system developer Notion Systems announced that investment company RSBG Advanced Manufacturing Technologies (RSBG AMT) has acquired 75.1% of Notion Systems.
RSBG competed against other interested parties, and it says Notion System has attractive growth prospects and a market-leading product range.
OLED inkjet printing developer Kateeva announced that it has established a strategic partnership with high-index material maker Pixelligent Technologies. The collaboration aims to optimize the light output efficiency by inkjet-printing of planarization layers over microlens arrays.
Collaboration Aims to Optimize Light Output Efficiency in Mobile Phones with Inkjet-Printed Planarization Layer over Microlens Arrays. To increase the efficiency, the companies suggest using a patterned structure followed by an inkjet-printed high-refractive index filling and planarization layer which enables more light from the OLED layer below to reach the top surface.
AU Optronics demonstrated two new OLED display prototypes at SID Displayweek 2021. The first display is a 4K 32-inch 144Hz inkjet-printed AMOLED panel.
The second display is a 5.6" rollable dual-sided AMOLED display - which shows images on both side of the display.
DSCC says that inkjet printing technologies for OLED display production is finally starting to gain traction, and the company sees IJP OLED display capacity to increase in a 137% CAGR from 2020 to 2025, to reach 7.1 million sqm.
As you can see from the chart, most of the growth will come from the printing of the quantum-dots color conversion layers in Samsung's QD-OLED fabs. Actual RGB inkjet printing will be confined to JOLED's fab which will start mass producing in 2021. In 2024, China Star (CSoT) will begin printing OLED TV panels at its T8 line.