Material Development for Pure and Full Color OLEDs

2023 Fiscal Year Final Research Report

• Project/Area Number: 21H02019
• 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: Kyoto University (2022-2023); Kwansei Gakuin University (2021)
• Principal Investigator: Hatakeyama Takuji 京都大学, 理学研究科, 教授 (90432319)
• Project Period (FY): 2021-04-01 – 2024-03-31
• Keywords: OLED / 色純度 / 熱活性化遅延蛍光 / 有機ホウ素化合物 / エネルギー変換効率

Outline of Final Research Achievements

By using the "multiple resonance effect" of boron and nitrogen atoms, we have successfully minimized the energy gap between the singlet excited state (S1) and the triplet excited state (T1) and suppressed structural changes in the excited state. This has led to the development of thermally activated delayed fluorescence (TADF) materials that exhibit ultrapure blue emission. In this study, under this molecular design, we developed narrowband green and red TADF materials in addition to improving the reverse intersystem crossing rate of blue TADF materials by optimizing the molecular structure. Furthermore, using the synthesized luminescent materials, we successfully developed full-color organic EL devices (OLEDs) with excellent energy conversion efficiency and color purity.

Free Research Field

有機材料化学

Academic Significance and Societal Importance of the Research Achievements

OLEDは，ディスプレイ分野での実用化が進んでいるが，エネルギー変換効率に課題を残しており，高効率なTADF材料の開発が盛んに行われている。一般的なTADF材料は幅広な発光スペクトルを示すという欠点があるが，本研究で開発した青色・緑色・赤色TADF材料は，20~40 nm程度の狭帯域発光を示すことから，ディスプレイ応用において光学フィルターにより余分なスペクトル領域をカットする必要がなくなり，エネルギー変換効率の大幅な向上，それに伴う消費電力の抑制が可能となる。これに加えて，最大輝度の向上や高精彩化も可能となり，社会的に大きな波及効果が期待できる。