SEL Archives ⋆ OLED

[2015 OLED Evaluation Seminar] Oxide TFT Technology that 2015 should Spotlight

December 10, 2015/in Technology /by OLEDNET

By Hyun Jun Jang

During the 2015 OLED Evaluation Seminar (December 4) hosted by UBI Research, Professor Jin-Seong Park of Hanyang University gave a presentation titled OLED Oxide TFT Technology Trend, discussing oxide TFT, related industry, and technological issues as well as TFT technology that should receive the spotlight in 2016.

Oxide TFT has an advantage of high mobility and large area uniformity compared to a-Si TFT. As such, it is being more applied to large area OLED panel and used in LG Display’s OLED TV.

Park revealed that there are mainly 4 issues regarding oxide TFT and led with the reliability issue. Oxide TFT is essentially in amorphous state but when crystalized, the density and crystallizability increase; as oxygen does not move away and stay in place, defects occur less and reliability is high. Japan’s SEL and Sharp published CAAC (C-Axis Aligned Crystal) structure related oxide TFT paper, and Cornell University produced CAAC oxide TFT by increasing the substrate temperature and adjusting oxygen’s partial pressure.

The second issue is composition ratio. Park reported that composition ratio is the most closely related characteristic to TFT’s mobility. He revealed that recently research is being carried out centering around IGZO (indium gallium zinc oxide), but also oxide TFT research with different composition ratio is continually published. For example, ITZO (indium tin zinc oxide)’s mobility has been reported to reach 30cm/V_sec, and BOE is working on the related research. Research results, which showed increased mobility and reliability for IGZTO, which is IZTO with G added, was published, as well as ZnON (zinc oxide nitride) TFT’s 100cm/V_sec mobility. BOE demonstrated ZnO TFT applied 14.1inch AMOLED.

The third issue is the device structure. Park explained that efficiency can increase when top gate structure is used to oxide TFT as parasitic capacitor is not needed, but that the process is difficult. However, Park reported that JOLED revealed when self-alignment is used the number of masks used can be reduced and increases performance. This structure is applied to OLED TV by LG Display.

Lastly, Park gave the safety of device as the last issue. Oxide TFT can exhibit degradation effects from light, oxygen, hydrogen, and moisture. Park reported that hydrogen particularly has great effect on the safety. He explained that although the current prevailing OLED TFT is LTPS, as the panel becomes larger there will be technological competition between oxide and LTPS. Reporting that TFT which is cost efficient and shows high performance in diverse factors such as resolution will dominate the market, Park concluded his presentation.

[2015 OLED 결산 세미나] 2016년 주목해야 할 Oxide TFT 기술은?

December 9, 2015/in 미분류 /by OLEDNET

유비산업리서치가 12월 4일 개최한 ‘2015 OLED 결산 세미나’에서 한양대학교 박진성 교수는 ‘OLED용 산화물 TFT 기술 동향’이라는 제목의 강연을 통해 산화물 TFT와 관련된 산업, 기술적 이슈를 되짚고 2016년 주목해야 할 TFT 기술에 대해 생각해보는 시간을 가졌다.

Oxide TFT는 a-Si TFT에 비해 mobility와 대면적 균일도가 높다는 장점이 있어 대면적 OLED 패널 중심으로 적용되는 추세이며 LG 디스플레이의 OLED TV에 적용되고 있다.

박 교수는 oxide TFT에 관련해서 크게 4가지 이슈가 있다고 밝혔다. 먼저 신뢰성에 대한 이슈에 대해 발표했다. 기본적으로 oxide TFT는 비정질 상태이지만 결정화할 경우 density와 결정성이 높아지기 때문에 산소가 빠져나가지 않고 제자리를 지키고 있어 defect이 적으며 신뢰성이 높다. 일본의 SEL과 Sharp는 CAAC(C-Axis Aligned Crystal) 구조와 관련된 oxide TFT 논문을 발표하였으며, 코넬 대학에서는 기판의 온도를 올리고 산소의 분압을 조절해서 CAAC oxide TFT를 제작했다.

두 번째 이슈로는 조성비가 있다고 밝혔다. 박 교수는 조성비는 TFT의 이동도에 가장 밀접하게 연관되어 있는 특성이라고 발표하며 최근에는 IGZO(Indium Gallium Zinc Oxide)를 중심으로 연구가 진행되었지만 다른 조성비를 가진 oxide TFT에 대한 연구결과도 지속적으로 나오고 있다고 밝혔다. 예를 들어 ITZO(Indium Tin Zinc Oxide)는 이동도가 30cm/V·Sec까지 올라간다는 성과가 나오기도 했으며 BOE에서 관련 연구를 하고 있다. 또한 IZTO에 G을 추가한 IGZTO는 이동도와 신뢰성이 더 올라갔다는 연구결과가 발표되었으며 ZnON(Zinc Oxide Nitride) TFT는 100cm/V·Sec까지 이동도가 올라갈 수 있다는 연구결과가 발표되었다. BOE는 ZnO TFT를 적용해 14.1인치의 AMOLED의 데모버전을 선보이기도 했다.

세 번째 이슈로는 소자의 구조가 있다고 발표했다. 박 교수는 top gate구조를 oxide TFT에 사용할 경우 기생 capacitor를 없앨 수 있어 효율을 높일 수 있지만 oxide TFT에 적용할 경우 공정이 어렵다는 단점이 있다고 밝히며 “하지만 JOLED에서 self-align을 사용할 경우 mask 수를 줄일 수 있고 특성이 좋아진다는 연구결과가 나왔으며 같은 구조를 LG 디스플레이에서 OLED TV에 적용하고 있다.”라고 발표했다.

박 교수는 마지막 이슈로 소자의 안정성을 꼽았다. Oxide TFT는 빛과 산소, 수소, 수분에 특성이 하락하는 degradation 현상이 나타날 수 있다. 특히 수소가 안정성에 큰 영향을 준다고 발표했다. 박 교수는 현재 OLED TFT의 주류는 LTPS이지만 패널이 대면적화 될수록 oxide와 LTPS와의 기술 경쟁이 나타날 것이고 cost efficiency와 해상도 등 다양한 factor에서 높은 성능을 발휘하는 TFT가 시장을 장악할 것이라고 밝히며 발표를 마쳤다.

[SID 2015] OLED’s Endless Evolution. SEL Reveals 8K Foldable AMOLED Panel

June 16, 2015/in Oled Video /by OLEDNET

During the author interview on 3 June, first day of SID 2015 Symposium, Japan’s SEL (Semiconductor Energy Laboratory) revealed 13.5 inch 8K foldable AMOLED panel and drew most attention in the room. During the last year’s SID, SEL showcased OLED’s most evolved product at the time with 5.9 inch foldable AMOLED panel and 13.3 inch 8K AMOLED panel.

The 13.5 inch 8K foldable AMOLED panel that was shown this year is a product that combined last year’s foldable and 8K technology. It utilized RGB laminated white OLED, RGB color filter, and top emission structure. Additionally, 664ppi was actualized through 3Tr+1C/Cell structure and external correction method.

[SID 2015] High Resolution OLED for Commercial Display Too! SEL Reveals 81inch Multi OLED Display

June 9, 2015/in Exhibition /by OLEDNET

Commercial display is a display installed in public areas. With the advantage of being able to deliver various information without being restricted to a place or time, it is becoming a new display market.

In order to lead increasingly expanding commercial display market, key panel companies are leaning toward high resolution and large size panel exhibitions. Recently released commercial displays have enlarged the size by attaching small LCD panels in a tile style creating bezel between panels. In LCD sector, commercial display products with minimized bezel are being developed.

However, 8K ultra high resolution commercial display has been produced without bezel through OLED. In SID 2015, SEL revealed world’s largest 81inch 8K OLED multi display that was produced by combining 36 13.5inch 8K flexible AMOLED panels.

The key technology is transparent sections of right and bottom edges of the panel. The FPC and scan driver sections of each panel are overlapped with corners of transparent edges (see below diagram).

Daiki Nakamura of SEL revealed that commercial displays of various sizes and shapes can be produced using flexible AMOLED panel and as it is suitable for applications on columns, commercial display can be a new market for OLED.

SEL had previously exhibited 27inch 8K multi OLED display using 4 13.5 inch 8K flexible OLED panels in Display Innovation 2014.

SEL’s 81inch 8K Multi OLED Display, SID 2015

[SID 2015] 커머셜 디스플레이도 고해상도 OLED로!, SEL 81inch Multi OLED Display 공개

June 6, 2015/in 미분류 /by OLEDNET

커머셜 디스플레이란 공공장소에 설치되는 디스플레이로서 다양한 정보를 언제 어디서든 자연스럽게 전달해 줄 수 있어 새로운 디스플레이 시장으로 떠오르고 있다.

주요 패널업체들도 점점 확대되어가는 커머셜 디스플레이 시장의 주도권을 리드하기 위해 고화질, 대형 size의 panel들을 전시하고 있는 추세이다. 하지만 최근 공개되고 있는 커머셜 디스플레이는 size를 키우기 위해 작은 LCD panel들을 tile 형식으로 여러장 붙여서 제작 되어지고 있기 때문에 panel과 panel 사이에 bezel이 존재하여 화면이 분할되어 보이는 단점이 존재한다. LCD 진영에서는 커머셜 디스플레이에서 panel과 panel의 bezel을 최소화 한 제품들이 개발되고 있다.

하지만 OLED를 통해 8K의 초고화질 대면적으로 bezel이 없이 커머셜 디스플레이를 구현되었다.

SID 2015에서 SEL은 13.5inch 8K flexible AMOLED panel을 36장(6×6)을 결합하여 world largest 81inch 8K OLED multi display를 제작하여 공개하였다.

핵심 기술은 panel의 우측과 하단의 edge부분을 투명하게 제작한 것으로 각 panel의 FPC와 scan driver 부분을 투명한 edge 부분의 모서리로 겹치는 것이다. (하단 그림 참조)

Source : SID 2015

SEL의 Daiki Nakamura씨는 “Flexible AMOLED panel을 이용하여 다양한 size와 모양의 커머셜 디스플레이를 제작할 수 있으며, 원형기둥 같은 곳에도 적용이 용이하기 때문에 커머셜 디스플레이에 OLED의 신규시장이 될 수 있을 것”이라 발표하였다.

한편 SEL은 Display Innovation 2014에서 13.5inch 8k flexible OLED panel 4장을 적용하여 27inch 8K multi OLED display 공개한바 있다.

SEL의 81inch 8K multi OLED display, SID 2015

[SID 2015] OLED’s Endless Evolution. SEL Reveals 8K Foldable AMOLED Panel

June 5, 2015/in Exhibition /by OLEDNET

During the author interview on 3 June, first day of SID 2015 Symposium, Japan’s SEL (Semiconductor Energy Laboratory) revealed 13.5 inch 8K foldable AMOLED panel and drew most attention in the room. During the last year’s SID, SEL showcased OLED’s most evolved product at the time with 5.9 inch foldable AMOLED panel and 13.3 inch 8K AMOLED panel.

The 13.5 inch 8K foldable AMOLED panel that was shown this year is a product that combined last year’s foldable and 8K technology. It utilized RGB laminated white OLED, RGB color filter, and top emission structure. Additionally, 664ppi was actualized through 3Tr+1C/Cell structure and external correction method.

[SID 2015] OLED의 끝없는 진화. SEL, 8K foldable AMOLED panel 공개

June 4, 2015/in 미분류 /by OLEDNET

일본의 SEL(semiconductor energy laboratory)이 SID 2015 심포지움 첫날인 6월 3일 author interview에서 13.5inch 8K foldable AMOLED panel을 공개하며 참가자들의 가장 큰 관심을 끌었다. SEL은 지난 SID 2014에서 5.9inch foldable AMOLED panel과 13.3inch 8K AMOLED panel을 공개하며 OLED에서 가장 진화한 제품을 선보인바 있었다.

이번에 선보인 13.5inch 8K foldable AMOLED panel은 작년에 선보인 foldable 기술과 8K 기술을 결합한 결과물로서 RGB 적층의 white OLED와 RGB color filer, top emission이 사용된 구조이다. 또한 3Tr+1C/Cell 구조와 external correction method를 적용하여 664ppi를 구현하였다.

Finding a way for OLED industry in flexible

June 25, 2014/in 미분류 /by OLEDNET

Samsung is preparing to introduce foldable AMOLED panel applied mobile product, and LG will release a new product with the flexible AMOLED panel in the latter half of this year.

As the flexible OLED commercializes, its R&D also accelerates. It was analyzed that the trend of papers published at SID 2014 is the flexible OLED as 9 more papers totaling 23 regarding the flexible OLED were published at SID 2014 than 14 papers 2013.

SEL displayed its best technology in the flexible OLED by introducing a tri-folded AMOLED panel, a book type AMOLED panel, and 13.5” and 5.2” high resolution flexible AMOLED panels at SID 2014. AMOLED latecomers such as AUO, BOE and CSOT also published papers on the flexible AMOLED panel and showed that more display companies are entering the flexible OLED development.

As such, active R&D on the flexible OLED is carried out by industry-academic-institute, and it is expected that the flexible will be more focused in the OLED display sector. A keyword of the flexible will differentiate it from the LCD and is expected to lead the display industry.

SEL’s 5.9” tri-folded AMOLED panel at SID2014

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