Organic light-emitting diodes possess 200% exciton production efficiency

2020 Fiscal Year Final Research Report

• Project/Area Number: 18H02047
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Single-year Grants
• Section: 一般
• Review Section: Basic Section 35030:Organic functional materials-related
• Research Institution: Kyushu University
• Principal Investigator: Nakanotani Hajime 九州大学, 工学研究院, 准教授 (90633412)
• Project Period (FY): 2018-04-01 – 2021-03-31
• Keywords: 有機EL / 一重項励起子開裂 / 近赤外有機EL / 熱活性化遅延蛍光

Outline of Final Research Achievements

In this study, we aimed to dramatically improve the exciton generation yield in organic light-emitting diode (OLED) by fusing two different spin conversion mechanisms: (1) thermally-activated delayed fluorescence (TADF), and (2) singlet fission (SF) processes. During this research project, the world's first SF-type OLED that exhibits over 100% exciton generation yield was realized by incorporating molecules showing SF into the OLED. Further, the basic physics of the TADF process was clarified from both experimental and theoretical aspects, and we succeeded in developing a highly efficient and durable NIR-OLED that can be applied to practical applications. Through this research project, the feasibility of "OLED exhibiting exciton generation yield of 200%" was obtained.

Free Research Field

有機光エレクトロニクス

Academic Significance and Societal Importance of the Research Achievements

本研究課題において、SF過程を示す分子をOLEDにおけるホスト材料として用いることで、励起子生成効率が100%を超える世界初のSF型OLEDを実現した。また、TADF過程の基礎物理を明らかにした。そしてこれらの学術的知見を基に、TADF過程とSF過程という二つの異なるスピン変換機構を融合することで、従来信じられていた励起子生成効率の理論限界値を超えることができる可能性を見出した。これにより、OLEDの特徴を生かしつつ、その発光強度は飛躍的に向上し、これまで想定されてきた用途のみならず、センサ光源や通信用光源等の新たな有機エレクトロニクス分野の学術・産業領域を開拓・創成できると期待される。