Printed OLED is coming, and the industry has an unprecedented consensus

But, wait! Why is there a new thing called "printed OLED"? Is this a new display technology? In the past five years, the declaration that OLED is “coming soon” has made my ears grow numb! Can we still trust the news this time? And with new technologies, what should we do with the original production lines and the production lines currently under construction?

There are too many questions! However, let’s take a look at what the latest news says: According to Korean media reports, Samsung Display and LG Display are preparing to introduce inkjet printing processes in their A3 and M2 production lines through cooperation with equipment manufacturers such as Kateeva and Tokyo Electron, as well as material manufacturers such as Merck and Idemitsu Kosan. The timetable is 2017.

Among them, the Samsung A3 production line is a 6th generation line, the target product is flexible OLED, and the scale is 15,000 substrates per month; the LG M2 line is an 8.5th generation line, the target product is rigid OLED, the current technology is white light OLED + color filter film, full-width evaporation, the scale is 26,000 substrates per month. Samsung A3 is the world's first purely flexible OLED line, focusing on small and medium-sized applications such as mobile phones and RGB OLED products; LG M2 is the world's first large-sized OLED mass production line, focusing on large-sized application products such as TVs. ——These two lines are currently the most advanced flat panel display panel production lines!

According to media reports, Mitsubishi Chemical has provided "OLED material" samples for inkjet printing to several potential users in the first half of this year; domestic TCL-led Juhua Printing has also signed a printing display material product cooperation agreement with Germany's Merck and others.

Based on the above news, it seems that "printing" + "OLED" has become the "core direction" for the progress of new next-generation flat panel display technology in the first half of the year. However, I believe many people have a question: Now that there are mass production technologies for OLEDs from large to small, why is printing technology still so popular? There are four reasons for this:

First of all, printing is a low-cost method. Just for the OLED material itself, the printing process saves 90% compared to the current steaming process; secondly, although the steaming process solves the entire steaming problem from the 3rd generation line to the 8.5th generation line, it fails to achieve triple steaming of the RGB three primary colors in large sizes. When the existing 8.5-generation line steaming process is used to manufacture RGB OLED three primary color panels, the yield rate drops significantly. Third, the effects of steaming and inkjet printing on the life characteristics of OLED materials are significantly different, and the latter is beneficial to long-lived OLED display products. Longevity is very important for large size applications. Fourth, the current trend in the panel industry is to concentrate on large-size lines, that is, new investment production lines are basically based on the 6th generation line as the starting standard. This makes the steaming process more conducive to lower-generation lines and encounters "upgrading" problems, while printing technology is more suitable for higher-generation lines.

These reasons together are enough to make printed OLED a trend of the times. However, the biggest bottleneck in printing OLED is the control of differences between each tiny printing dot, and the development of equipment for printing extremely small sub-pixel units. The former is a key bottleneck in the entire printed display industry, while the latter is mainly a problem for small and medium-sized display products. ——In other words, for printing OLED, ink stability is not the final big issue, equipment accuracy and stability are the real test. The latter can only be truly solved from an engineering perspective after a demonstration production line is established.

"Solving the problems of printing accuracy and process stability in specific engineering practices and under large-scale conditions" - this is the real bottleneck of current OLED printing displays. This is also a problem that Samsung, LG, Juhua Printing and other companies are making their greatest efforts to solve.

Is this problem easy to solve? Someone must ask that. However, as a comparison, the problems encountered by steaming technology in the manufacturing of large-size OLED panels can also be summarized as "accuracy and process stability." In other words, the core issues after large-scale printing and steamed OLED are the same - who will win in the future depends on which technical route is easier to solve this problem.

In other words, the OLED printing technology boom in 2016 can be understood as follows: steaming large-size OLEDs is a bit more difficult than imagined, so everyone chooses to try another way - printing OLEDs. However, this also has a greater impact on color TVs. Regarding the OLEDization of mobile phones, whether there is printing technology or not will not cause changes in the industrial popularization process.

"Don't be happy too early"! Because when it comes to OLED, consumers have been put off too many times. Since 2012, Samsung and LG’s promise of “OLED TV is coming” has been repeatedly delayed.

The reason for this is not that the manufacturers do not work hard, but because there are "too many choices" and energy is scattered, and at the same time, the technical difficulties are relatively large. These factors combine to cause "Samsung and LG" to continue to break their promises.

From a technical perspective, Samsung’s earliest favorite route was “low-temperature polysilicon, steamed, RGB OLED”. However, the fact is that it is difficult to increase the size of low-temperature polysilicon TFTs, and it is also difficult to increase the size of the steaming process. It is now almost difficult to achieve economical yields when RGB OLEDs are steamed to large sizes. Later, Samsung proposed "laser thermal transfer" printing OLED, but it was not ultimately successful. LG is smart and adopts the route of metal oxide TFT + half-width evaporation + WOLED + color filter film. This route bypasses some of the most difficult problems, such as RGB technology, and takes the lead in launching large-scale mass-produced products.

From these technical analyses, you can see that the OLED roadmap is not easy: there are differences between glass substrates and flexible substrates on TFT, and there are two major technical routes, low-temperature polysilicon and metal oxide; there are at least four technologies for OLED coating: half-width evaporation, full evaporation, laser thermal transfer, and inkjet printing; there are also two major differences in final product selection: WOLED + color filter film and RGB OLED.

So, the conclusion is: there are too many possible choices, which increases the possibility of going in the wrong direction. This is the key "opportunity risk" that OLED has not yet arrived. If the entire industry and all resources were concentrated on inkjet RGB OLED from the beginning, perhaps the entire industry process would be much faster.

The best news for next-generation flat panel displays in 2016 - manufacturers finally really believe that "inkjet printing" is the most critical process point. Even electroluminescent QLED, the technology used by Samsung to "anti-OLED", must be based on the "inkjet printing" process. Once an unprecedented consensus on "inkjet printing" is formed in the OLED and QLED display industries, it will be possible for OLED to accelerate its arrival.

"Although the difficulties are relatively large," "the industry has reached an unprecedented consensus" and shared strengths, and years of industry efforts have made other key links such as OLED materials, OLED ink formulas, and TFT process materials "quite mature." This is the biggest good news for the OLED industry at present.

At this point, the article is basically over, but there is a question at the beginning that needs additional answers: Printed OLED is coming, what to do with the existing OLED lines and lines under construction?

First of all, there is no need to introduce printing technology for small and medium-sized lines. The current ones used by Zidu are also very good, so just continue to use them after they are built; secondly, there are production lines under construction, and the large-sized lines only have LG's 9th generation line. This line will not be mass-produced until 2018, which means that its technology roadmap can be determined after the M2 line test of printed OLED in 2017; Third, other small and medium-sized lines under construction can be scientifically adjusted by referring to the demonstration results of LG and Samsung; fourth, the difficulty of steaming OLED lines and converting to printed OLED lines is not very big, mainly due to cost issues; fifth, the only large-sized OLED lines that have been mass-produced are LG's M1 and M2, and the scale of the two lines is not large, so the cost of converting them into printed lines is acceptable.

Therefore, you don’t need to worry too much about the impact of new technologies on existing OLED lines. Because OLED has not gone very far before, even if it is rolled back and started again, it will not be a big problem. Moreover, the steaming process accounts for less than 30% of OLED panel equipment.