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.
The latest OLED ink jet news:
Notion Systems and M.Braun announced a strategic partnership in OLED processing equipment. The two companies will combine their best-in-class OLED production technology to improve the production process offers and enhance market access in Asia.
M.Braun is a developer of glove boxes, inert gas purification and automation solutions while Notion Systems is a leading developer of industrial inkjet-printing systems for functional materials, and both companies already enjoy the growing demand of OLED manufacturing in Asia.
In December 2019 BOE unveiled a 55" 8K (160 PPI) OLED TV prototype produced by inkjet printing. The panel achieves a maximum brightness of 400 nits and a color gamut of 95% DCI-P3.
At SID Displayweek 2020, the company demonstrated this display and gave more details regarding its production process and display structure.
Samsung Display has developed a 18.2" 2560x1440 202 PPI inkjet-printed OLED display, that features the highest current efficiency of any inkjet-printed OLED, with the brightness at 350 cd/m2 (full white).
Samsung Display says that the high brightness was achieved by tuning the top-emission device structure with high performance soluble materials. The high pixel resolution was achieved by modulating the jetting waveform for ejecting ink drops and improving the drop placement accuracy by selecting the right ink formulations in terms of viscosities and surface energies.
This is a sponsored post by Notion Systems
Notion Systems received a major order of several n.jet display inkjet printing systems from a major Taiwanese display manufacturer and underlines its leading position in the market.
The n.jet display series prints functional layers in various steps of display production, and for various display technologies. This includes rigid, flexible, OLED, QLED, and LCD displays. In addition to its unparalleled precision, the platform complies with the highest demands on process environment and process stability. Specifically developed features, like the no.mura printing technology solve long-standing challenges in the industry and enable an efficient, additive use of the valuable materials involved in manufacturing the next generation displays.
This is a sponsored post by Noctiluca
Poland-based TADF developer Noctiluca reports that the company continues to improve its emitter platform, and the company recently concluded testing a new family of emitters that have revealed great TADF properties, good to excellent QY and blue emission. Noctiluca released the raw data (available from company under the NDA) that details the performance of several new blue emitters. Here is a link to the summary of these results.
Noctiluca’s Team have a history of making custom high purity compounds to specific needs, and its TADF compound family has a high level of customization which will allow the company to tailor its materials for specific OLED stacks. In fact the company's next step is to work with industry leaders and OLED material developers to test its materials within commercial-grade OLED stack architectures to continue its development work and enhance the performance of its OLED emitters.
US-based OLED inkjet printing developer Kateeva announced that Tianma has ordered an R&D 200mm YIELDJet Explore printing system to expand its OLED research and development programs.
Kateeva reveals that Tianma is already using its TFE system in its OLED mass production fabs. Kateeva also says that this tool will be the 60th Kateeva printer at customer sites.
DSCC updated its OLED material market forecasts, seeing a lower growth ahead. DSCC says the AMOLED stack material market will grow from $928 million in 2019 to $2.06 billion in 2024 in a CAGR of 17%. Only a couple of months ago DSCC estimated that the market in 2024 will reach $2.69 billion - and even these were reduced from earlier estimates due to COVID-19.
DSCC says that the main reason behind the reduction in its forecast is lower OLED TV capacity. The company now expects a slower ramp up at the Guangzhou fab, and LG's P-10 10.5-Gen fab is now removed from the forecast period.
JDI developed a new OLED production technology, looking for customer partners to commence mass production
Japan Display says it is developing a new OLED production technology that will enable higher resolution and higher efficiency OLED displays, and the company is in talks with potential customers regarding a joint investment in producing next-generation OLEDs.
According to JDI's CEO, the company is using a new manufacturing technology that is different to the evaporation method currently used by OLED makers. It is not clear what is meant by that - it could be an inkjet-printing technology (but achieving high resolution for smartphone displays with inkjet printing is a challenge) or something like OVPD or OVJP - or a new technology developed in-house at JDI.
JOLED announced that TCL CSoT has invested 20 billion Yen (around $187 million USD) in the company, and has also signed an agreement to jointly develop OLED TV printing technologies.
This is a very interesting development. TCL has been a long time believer in inkjet printing for OLED displays, and the company has established Juhua Printing in 2016 (together with TianMa and other collaborators) as an "open-innovation platform" to develop ink-jet printing of OLED panels. JOLED was not involved as far as we know in this alliance - so has TCL given up on Juhua and is now aiming to rely on JOLED's technology?
DSCC updated its OLED material market estimates, saying that AMOLED stack material sales will grow from $951 million in 2019 to $2.69 billion in 2024 - a CAGR of 23%. These new estimates take into account DSCC's reduced input area forecast due to the slowdown in demand cased by the Covid-19 pandemic.
DSCC says that incremental improvements in material utilization and price reductions, material costs per square meters will decline in the future. The unyielded cost of producing a square meter of a WOLED TV panel will decline from $95.21 in 2019 to $56.11 in 2024.