- The Guangzhou government released a file showing a China Star Optoelectronics Technology (CSOT) inkjet display project with a construction time of 2021–23 and a total investment of around ¥48 billion.
- Although this is a great move for adopting inkjet technology in the mass production of displays, this technology still needs to develop further to compete with existing products.
- In the long run, reducing the device structure and combining the electron transporting layer (ETL) and electron injection layer (EIL) into one printable layer might help inkjet display to overcome some of its drawbacks. This would also minimize production costs one step further by reducing the needed materials, increasing the material usage rate, and increasing the yield.
After months of waiting, updates for CSOT’s massive inkjet printing production line project are available. On June 20, 2020, the Guangzhou government released a name list of key construction projects for 2020 where CSOT’s T8/T9 project was officially mentioned for the first time.
According to the document, the project is still in the planning phase with its construction time targeted for 2021–23.
More details about the ongoing CSOT T8/T9 project
According to the original plan, CSOT planned to build both T8 and T9 in Guangzhou, China. T8 was estimated to be a smaller-size pilot line with inkjet organic light-emittiong diode (OLED) technology, whereas T9 was estimated to be a Gen 8.5 full-size inkjet OLED line. However, the construction plan changed over time, so the original T8 pilot line might be cancelled and replaced by joint research with JOLED in Japan. In the meantime, the original T9 full-size mass production line project might be renamed T8.
According to the local government’s file, this new T8 project is named “China Star printing and rollable display R&D and production base project”. The total investment is ¥46 billion ($6.6 billion), and the construcion period is set for 2021–23. Out of the total investment of ¥46 billion, 3 million is planned to be spent in 2020 for material preparations.
Compared with BOE Technology (BOE), CSOT is more aggressive in adopting inkjet technology in mass production. Having a new T8 project in 2021 will not only boost the inkjet printing display industry’s development but also enhance CSOT’s competitiveness in global display production.
However, although inkjet OLED/quantum-dot (QD) displays have many potential advantages compared with white OLED (WOLED) technology, it also has some potential drawbacks that might limit further development. One of the most worrisome factors is that inkjet display’s long and complex process might harm its yield.
- Currently, inkjet OLED panels still have many layers inside, and only some of them can be printed. Since the printing of each layer needs many steps and substrates have to be moved constantly between vacuum and air atmospheres, there are lots of ways for the process to go wrong. This leads to poor yield and high production costs.
Luckily, CSOT has years to solve the aforementioned drawbacks. One possible solution is to simplify the device struture via material innovation.
- The steps in the process can be vastly reduced by combining the hole injection layer (HIL) and hole transport layer (HTL) as well as making a new, single, printable layer of electron transfer material to replace both ETL and EIL.
- In addition, since the layers of material needed are reduced and material usage efficiency can be increased to 90% and above, the production cost might further decline. Then, it would be able to compete with WOLED head-to-head and even have some cost advantages compared with high-end LCDs.
Estimations for the CSOT Gen 8.5 injet printing (IJP) mass production line project are as follows:
- Although it has “rollable” in its name and CSOT had recently increased its investments in developing flexible IJP panels, this new T8 project might still make rigid IJP OLEDs its core product first.
- This new Gen 8.5 IJP line might not have multi-model glass (MMG) technology in its initial phases because of the challenges faced in its current printing process.
- This line will likely use JOLED’s technology and printers if the joint research between JOLED and CSOT goes well in the next few years.
- Before inkjet technology is adopted in actual mass production and used to replace other competitive technologies, many innovations, such as structural reductions and material innovations, are needed.