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Innovation Japan 2022 (October 4 - 31)


Innovation Japan 2022 - Online Close up topics of solution-processed OLEDs

October 4th, Innovation Japan 2022 - Online has started by the online method. Many demonstrations are disclosed until October 31 by a specific homepage. Topics for OLED are closed up based on the homepage.

Solution-processed OLED is obtained by use of organic Nanocrystals

As concerns "equipment/device category", the research group of Nara Institute of Science and Technology (Sai Mizuno assistant professor) reported "Solution-Processed Organic Light-Emitting Diode Displays Using High-Quality Water-Dispersed Organic Nanocrystals".

Fig 1. Image of solutiopn-processed OLED using organic Nanocrystals
In this device, as figure 1, (thiophen/phenylene)co-oligomer (TPCO) was used as organic emitting material. If this Nanocrystal is used, high quality OLED with low voltage driving and high durability against high temperature is obtained because of forming of 0 dimension state density. Emission color can be changed by grain size because of quantum effect of Nanocrystal. For this reason, RGB full color OLED is easily obtained by control of grain size.

Furthermore, originally developed manufacturing method of this Nanocrystal is based on water series. And also, an additive is not necessary for this dispersion liquid. Moreover, agglomeration of Nanocrystals and interfusion of additive into Nanocrystals are not generated. As a result, independent water series dispersion liquid is obtained stably.

Solution-processed gas barrier film is printed by IJ printing in the near future

On the other hand, in "category of JST enterprise exhibition", the Suzuri professor research room (Yamagata University) announced manufactured ultra-high barrier technology by solution-processed, and appealed high barrier structure was obtained almost same as that of glass.


Pic 1. Flexible OLED using gas barrier encapsulatuion
Fig 2. Process image of solution-processed gas barrier film
In this process, a precursor Perhydropolysilazane (PHPS) is coated and then, its film is irradiated with VUV light (wavelength 172 nm) in N2 environment and at RT. As a result, dense inorganic SiNx film is obtained. Its water vapor permeability (WVTR) was 10-4 g/m2/day, which was world highest value among solution-processed gas barriers. Furthermore, in the near future, the inkjet printing (IJ) method will be adopted as coating and patterning method. In short, direct patterning process will be used due to correspondence with DX.

Picture 1 shows a flexible OLED (200 × 50 ㎜), was encapsulated by this process. Superior flexibility same as Ra = 5 ㎜ was gained.

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