Development of molecular systems focusing on triplet excited states for high performance organic devices

2021 Fiscal Year Final Research Report

• Project/Area Number: 19H02790
• 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: Mamada Masashi 九州大学, 工学研究院, 助教 (60625854)
• Project Period (FY): 2019-04-01 – 2022-03-31
• Keywords: 有機EL / OLED / TADF / 逆項間交差 / 近赤外

Outline of Final Research Achievements

There is increasing interest in excited state dynamics related to triplet states such as thermally activated delayed fluorescence (TADF) process for realizing highly efficient organic light-emitting diodes (OLEDs). Recent challenges include color purity, efficient deep-blue emission, exciton decay lifetimes, reverse intersystem crossing rates (kRISC), low-efficiency roll-off in organic light-emitting diodes (OLEDs), and long device lifetimes. In this study, we developed molecular design for stable emitter molecules to improve the device durability. Newly developed TADF molecules exhibited high excited state energies with dense alignment of several excited states. TADF-assisted fluorescence (TAF) OLED showed high external quantum efficiency with high color purity for blue. We also succeeded in developing highly emissive near-infrared emitters for high performance TAF-OLED.

Free Research Field

有機機能材料

Academic Significance and Societal Importance of the Research Achievements

青色OLEDにおいて、三重項励起子が強く関与するりん光やTADFの実用化が遅れている原因は素子耐久性の低さにあるが、本研究において分子の安定性や励起子過程が素子耐久性に与える影響について多くの知見が得られたことは、さらなる特性向上に寄与する。一方、近赤外発光デバイスは通信やセンシング用途などを中心として産業的な需要が非常に高く、高い発光効率を示す有機材料を創出できたことは、近赤外OLEDの開発を促進し、有機デバイスの特徴を活かした新たなアプリケーションの開拓につながると期待される。