Photon up-conversion promoted by molecular vibration

2023 Fiscal Year Final Research Report

• Project/Area Number: 22K19008
• Research Category: Grant-in-Aid for Challenging Research (Exploratory)
• Allocation Type: Multi-year Fund
• Review Section: Medium-sized Section 32:Physical chemistry, functional solid state chemistry, and related fields
• Research Institution: Kobe University
• Principal Investigator: Kobori Yasuhiro 神戸大学, 分子フォトサイエンス研究センター, 教授 (00282038)
• Project Period (FY): 2022-06-30 – 2024-03-31
• Keywords: 三重項－三重項消滅 / 時間分解電子スピン共鳴法 / スピン変換 / 蛍光量子収量 / 強相関多重励起子 / スピン双極子相互作用 / 交換相互作用 / アップコンバージョン

Outline of Final Research Achievements

The microscopic motion of electron spins inside an organic thin-film solid capable of efficiently converting near-infrared light into visible light was investigated, and the authors succeeded for the first time in the world in capturing the highly efficient generation of short-wavelength light by the spin state change of triplet excitons formed as intermediates through rotational diffusion motion inside the solid. The model analysis of the motion of triplet exciton pairs (TT) formed during the TTA reaction revealed that the singlet exciton with luminescent properties is generated with an efficiency of 77% due to the spin multiplicity conversion, indicating that the modulation of the spin-dipole interaction by the orientation motion of the triplet exciton is responsible for the generation of short wavelength light. The modulation of the spin-dipole interaction due to the orientational motion of the triplet exciton plays an important role in the efficiency of the TTA reaction.

Free Research Field

光スピン化学

Academic Significance and Societal Importance of the Research Achievements

中間体として生成する三重項励起子が固体内部の回転拡散運動でスピン状態を変化させて短波長の光を高効率に生じる様子を捉えることに世界で初めて成功した。これにより、今後、高効率光エネルギー変換デバイス開発が進展し、世界的なエネルギー問題解決に貢献するとともに、人体に害のない近赤外光を光アップコンバージョンさせ利用する光線力学的ながん治療や診断など幅広い分野への展開が期待される。