Kyushu University Academic Staff Educational and Research Activities Database
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Onda Ken Last modified date:2020.06.19

Graduate School
Undergraduate School

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 Reseacher Profiling Tool Kyushu University Pure
Academic Degree
Country of degree conferring institution (Overseas)
Field of Specialization
Spectrochemistry, Ultrafast spectroscopy
Total Priod of education and research career in the foreign country
Research Interests
  • Structural analysis of photofunctional materials studied by time-resolved infrared vibrational spectroscopy
    keyword : Infrared Spectroscopy, Ultrafast Spectroscopy, Photochemistry, Photofunctional Material, Reaction Dynamics
Academic Activities
1. Masaki Saigo, Kiyoshi Miyata, Sei'Ichi Tanaka, Hajime Nakanotani, Chihaya Adachi, Ken Onda, Suppression of Structural Change upon S 1 -T 1 Conversion Assists the Thermally Activated Delayed Fluorescence Process in Carbazole-Benzonitrile Derivatives, Journal of Physical Chemistry Letters, 10.1021/acs.jpclett.9b00810, 10, 10, 2475-2480, 2019.05, Thermally activated delayed fluorescence (TADF) molecules are gathering attention for their potential to boost the efficiency of organic light-emitting diodes without precious metals. Minimizing the energy difference between the S 1 and T 1 states (ΔE ST ) is a fundamental strategy to accelerate reverse intersystem crossing (RISC). However, the lack of microscopic understanding of the process prevents adequate design strategies for efficient TADF materials. Here, we focused on four carbazole-benzonitrile (Cz-BN) derivatives that possess identical ΔE ST but distinct TADF activities. We systematically compared their geometrical dynamics upon photoexcitation using time-resolved infrared (TR-IR) vibrational spectroscopy in conjunction with quantum chemical calculations. We found that the most TADF-active molecule, 4CzBN, shows little structural change after photoexcitation, while the TADF-inactive molecules show relatively large deformation upon S 1 -T 1 conversion. This implies that the suppression of structural deformation is critical for minimizing the activation energy barrier for RISC in cases of the Cz-BN derivatives..
Membership in Academic Society
  • American Chemical Society
  • American Physical Society
  • The Physical Society of Japan
  • The Chemical Society of Japan