| Project/Area Number |
24KF0245
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| Research Category |
Grant-in-Aid for JSPS Fellows
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| Allocation Type | Multi-year Fund |
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| Section | 外国 |
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| Review Section |
Basic Section 35030:Organic functional materials-related
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| Research Institution | Kyushu University |
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Principal Investigator |
安達 千波矢 九州大学, 工学研究院, 教授 (30283245)
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| Co-Investigator(Kenkyū-buntansha) |
BARMAN DEBASISH 九州大学, 工学研究院, 外国人特別研究員
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| Project Period (FY) |
2024-11-15 – 2027-03-31
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| Project Status |
Granted (Fiscal Year 2024)
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| Budget Amount *help |
¥2,000,000 (Direct Cost: ¥2,000,000)
Fiscal Year 2026: ¥800,000 (Direct Cost: ¥800,000)
Fiscal Year 2025: ¥1,000,000 (Direct Cost: ¥1,000,000)
Fiscal Year 2024: ¥200,000 (Direct Cost: ¥200,000)
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| Keywords | Multiresonance / charge transfer / molecular orientation / TADF / EQE |
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| Outline of Research at the Start |
We anticipate that the combined effects of multi-resonance (MR) and charge transfer (CT) will offer flexibility in tailoring TADF molecular design. This will have a transformative impact on photophysics and device physics, opening a new paradigm and paving the way for future advancements in TADF emitter designs for high-efficiency blue OLEDs.
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| Outline of Annual Research Achievements |
We summarize our approach with two simple donor-acceptor (D-A) and donor-acceptor-donor (D-A-D) design strategies, which combine short-range (SR) charge transfer (CT) with main long-range (LR) CT, resulting in multi-resonance (MR) CT-type thermally activated delayed fluorescence (TADF) emitters. By modifying the auxiliary push-pull connection between a carbazole donor and a boron-based acceptor core, we constructed C-C bond-extended DBACzPh and DBADCzPh emitters with strong TADF emission in solution and thin films. Preferential 100% horizontal molecular orientation resulted in balanced bipolar carrier transport and effective host-to-dopant energy transfer in a high-polarity host matrix. Thereby, DBADCzPh significantly boosts outcoupling efficiency with a record-high EQE of over 40%.
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| Current Status of Research Progress |
Current Status of Research Progress
1: Research has progressed more than it was originally planned.
Reason
We successfully synthesized two of the proposed emitters. Afterward, we could obtain feasible optical properties. Further, evaluate the exclusive photophysics and device physics of the synthesized emitters as planned.
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| Strategy for Future Research Activity |
We summarize all the obtained results and prepare them for publication. Unlike very high EQE, the device lifetime of these emitters was not satisfactory for the sky-blue emitter. Therefore, we plan to synthesize cyclic MRCT-type D-A-D-A structures to achieve blue emission with improved operational device lifetime. We believe that a cyclic framework could reduce molecular vibration and enhance molecular stability, thereby reducing the likelihood of unnecessary chemical degradation. At the same time, the reverse intersystem crossing rate is also expected to be enhanced by the molecular rigidity factor.
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