Semiconductor Energy Laboratory Co., Ltd.

SEL develops and prototypes various displays with a crystalline oxide semiconductor such as CAAC-OS^®. FETs made with crystalline oxide semiconductors enable high-resolution and low-power consumption displays^[1].
Our OLED display prototypes, such as 8K displays, ultra-small and high-resolution displays, flexible displays (foldable displays and multi-displays), and touch-sensor-embedded displays, are characterized by their high resolution and high contrast. There is a high expectation for these technologies to be used in the mobile devices and medical devices.

Liquid crystal displays including our CAAC-OS are in widespread use across the display industry, an example of which is its adoption in smartphone displays in 2012 as the world's first liquid crystal displays including OS.

Now, we are also considering expanding our crystalline oxide semiconductor technology to backplanes of micro-LED displays, which are attracting attention as third generation displays after LCDs and OLEDs.

8K display

World's Smallest Direct-View 8K Display with High-Aperture Ratio using MML Technology

SEL have developed high-resolution OLED displays exceeding 1000 ppi by application of thin-film transistors using crystalline oxide semiconductors to drivers^[1]. We also achieved ultra-high-resolution 13.3-inch 8K display creating a greater feeling of depth in images and stereoscopic effect^{[2], [3]}. We have further increased the resolution to realize 8K displays in various sizes, including an 8.3-inch display exceeding 1000 ppi^{[4], [5]}.
Initially, color displays were fabricated by combination of white-emission OLED devices and color filters, but now OLED materials for different colors are separately patterned by a photolithography technique, thereby achieving a higher aperture ratio, lower power consumption, and higher color purity.
We call this fabrication technology metal mask-less lithography (MML).



[1] K. Yokoyama et al., “A 2.78-in 1058-ppi Ultra-High-Resolution OLED Display Using CAAC-OS FETs,” SID Symp. Dig. Tech. Pap., 46, 1039 (2015).
[2] S. Kawashima et al., “13.3-in. 8K x 4K 664-ppi OLED Display Using CAAC-OS FETs,” SID Symp. Dig. Tech. Pap., 45, 627 (2014) , Received SID Distinguished Paper Award.
[3] R. Yamamoto et al., “13.3-inch 8k4k 664-ppi 120-Hz 12-bit OLED Display,” SID Symp. Dig. Tech. Pap. 47, 53 (2016), Received SID Distinguished Paper Award.
[4] M. Shiokawa et al., “A 1058 ppi 8K4K OLED Display Using a Top-Gate Self-Aligned CAAC Oxide Semiconductor FET,” SID Symp. Dig. Tech. Pap. 47, 1209 (2016).
[5] S. Eguchi et al., “An 8.3-inch 1058-ppi OLED Display with Side-by-Side Pixel Structure Fully Fabricated by Photolithography,” SID Symp. Dig. Tech. Pap., 209 (2023).

Ultra-small and high-resolution displays for AR/VR

AR/VR displays require higher resolution and higher brightness. We have developed ultra-small and high-resolution displays using our crystalline OS^[7]. A stacked structure of a pixel circuit using our original OSLSI^® and a driving circuit using silicon (Si)^{[8], [9]} enables displays with narrow bezels and large sizes. Furthermore, a structure using only oxide semiconductor (OS), without Si, is expected to facilitate low-cost mass production.


[7] S. Katsui et al., “5291 ppi organic light-emitting diode display using field-effect transistors including a c-axis aligned crystalline oxide semiconductor,” J. Soc. Inf. Disp., 50(1), 311 (2019).
[8] K. Kato et al., “5291-ppi OLED Display Enabled by Monolithic Integration of C-axis-aligned Crystalline IGZO FET and Si CMOS,” IDW '21 Proc., 177 (2021).
[9] Y. Tamatsukuri et al., “5009-ppi, 10000-cd/m2, OLED/OS/Si Structure Display with Built-in CPU and Display Driver,” SID Symp. Dig. Tech. Pap., 193 (2025).
https://doi.org/10.1002/jsid.2058

We also succeeded in developing ultra-high-resolution displays exceeding a resolution of 3000 ppi and a luminance of 5000 cd/m² by combination of the stacked structure and MML technology^{[10], [11]}.

[10] T. Saito et al., “Layout of 1.50-inch, 3207-ppi OLED Display with OSLSI/SiLSI Structure Capable of Division Driving Fabricated through VLSI Process with Side-by-Side Patterning by PPhotolithography,” SID FETs,” Symp. Dig. Tech. Pap., 94 (2022).
[11] M. Kozuma et al., “1.5-inch, 3207-ppi Side-by-Side OLED Display Capable of 32-Division Driving with OSLSI/SiLSI Structure Fabricated by Photolithography,” SID Symp. Dig. Tech. Pap., 384 (2022).

foldable display^®

We developed CAAC-OS technology, OLED technology, and flexible technology independently, and unveiled a foldable OLED display^{[12], [13]} in 2014.
The foldable display we introduced in 2015 incorporates a capacitive touch sensor that withstands over 100,000 times of bending and touch function^[14].


[12] Y. Jimbo et al., “Tri-Fold Flexible AMOLED with High Barrier Passivation Layers,” SID Symp. Dig. Tech. Pap., 45, 322 (2014).
[13] R. Komatsu et al., “Repeatedly Foldable Book-Type AMOLED Display,” SID Symp. Dig. Tech. Pap., 45, 326 (2014).
[14] K. Watanabe et al., “An 8.67-in. Foldable OLED Display with an In-cell Touch Sensor,” SID Symp. Dig. Tech. Pap., 46, 246 (2015).
[15] K. Takahashi et al., “13.3-inch 8k4k 664-ppi Foldable OLED Display Using Crystalline Oxide Semiconductor FETs,” SID Symp. Dig. Tech. Pap., 46, 250 (2015).