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[IMID 2018] Can Blue TADF and Hyperfluorescence meet both efficiency and lifetime?

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At IMID 2018 in Busan, BEXCO on August 31, Junji Adachi, CEO of Kyulux disclosed the performance of hyperfluorescence, which adds TADF dopant to the existing fluorescent host and dopant.

The color coordinates of the yellow hyperfluorescence revealed by Junji Adachi are (0.49, 0.50), the FWHM (Full Width at Half Maximum) is 76 nm, the EQE is 15.7% on 1000 nit basis, and the LT50 is 62,000 hours by 1000 nit. And the color coordinates of the green hyperfluorescence are (0.28, 0.65), the FWHM (Full Width at Half Maximum) is 31 nm, the EQE is 20.6% on 1000 nit basis, and the LT50 of 1,000 nit is 48,000 hours.

Junji Adachi also revealed the performance of Blue hyperfluorescence, which is currently under development. The maximum emission wavelength of the blue hyperfluorescence is 470 nm, the EQE at 1000 nit is 22%, and the LT50 at 750 nit is 100 hours. In particular, he predicted that the performance of Blue hyperfluorescence would be further improved in the future, saying that it began to improve rapidly in the first half of 2018.

In the following announcement, Dr. Georgios Liaptsis of CYNORA explained about the deep Blue under development, emphasizing that the wavelength should be 460 nm and the CIEy should be within 0.15. He revealed its performance, adding that CYNORA has been carrying out the necessary research to make the lifetime of deep Blue as long as that of sky Blue even with phenomenon that the life span is getting longer as the Blue goes closer to the sky Blue

Fluorescent blue is currently used for the Blue of all OLED applications. Attention is growing whether Blue TADF or Blue Fluorescence can be commercialized to realize better efficiency and lifetime than existing fluorescent blue.

[IMID 2018] LG Display, showcased 2-stack RGB OLED for automobile OLED with improved life span.

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At IMID 2018 held in BEXCO, Busan on August 29, Kim Kwan-Soo, research fellow of LG Display presented about a new OLED technology for automotive displays.

Kim said that RGB OLEDs applied to mobile devices and WRGB OLEDs applied to TVs do not satisfy customers’ needs in terms of life span. To solve this issue, he introduced 2 stack RGB OLED in which RGB OLED has the same tandem structure as WRGB.

Because 2 stack RGB OLED can be thick due to adding a layer of CCL (charge generation layer) to the multi-layer structure, HTL is made thinner than before and the charge balance of the emitting layer is optimized.

As a result, the 2-stack RGB OLED shows 1.5 ~ 2 times higher emitting efficiency than the 1-stack RGB OLED. Its lifetime is increased by 4 times on T80 basis.

However, the 2-stack structure has a disadvantage in that it has higher power consumption than the general structure. Thus, it is necessary to make efforts to solve this disadvantage.

[IMID 2018] LG Display and Samsung Display exhibited a large number of large, and small & medium sized OLED applications.

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LG Display and Samsung Display introduced a number of applications using OLED at IMID 2018 held in BEXCO, Busan, drawing attention from many visitors. In particular, LG Display displayed its strategies mostly for large OLED applications such as 77-inch transparent OLED and 55-inch video wall OLED, while Samsung Display introduced the small and medium sized OLED applications mainly for automotive and virtual reality devices.

First, the panel thickness of the 77 inch transparent flexible OLED introduced by LG Display is 400 μm, the bending radius is 80 mm, and the luminance is 200 nit based on full white.

LG Display explained that it would improve the required transmittance and durability. Also, it commented that the goal is to reduce bezel to 0.5 mm at its display of 4 FHD OLEDs with 3.8 mm bezel.

In addition, LG Display presented a 1200ppi 4.3-inch WRGB OLED for virtual reality devices. One official explained that WRGB OLED, which represents the resolution by etching the color filter, would be advantageous for higher resolution than RGB using the deposition method.

Meanwhile, Samsung Display exhibited a number of automotive OLEDs, including unbreakable OLED for 6.22 inch steering wheel, 1000R curved OLED for passenger monitor, transparent OLED for HUD, S-curved OLED for CIO and rollable OLED. The concerned official expects the OLED to be widely applied to inside automobiles because it has excellent design autonomy, compared to LCD.

He added “Although there are many things to be improved, such as brightness and reliability, it is continuously improving the required performance through the feedback from European customers”.

Furthermore, Samsung Display showcased light field display and 2,000ppi resolution RGB OLED for virtual reality devices.