Spatially-resolved analysis of triplet-triplet annihilation photon upconversion solid-state systems using spectromicroscopy

2022 Fiscal Year Final Research Report

• Project/Area Number: 20K05653
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 35030:Organic functional materials-related
• Research Institution: Rikkyo University
• Principal Investigator: Mitsui Masaaki 立教大学, 理学部, 教授 (90333038)
• Project Period (FY): 2020-04-01 – 2023-03-31
• Keywords: フォトンアップコンバージョン / 三重項状態 / エネルギー移動 / 顕微発光分光 / 三重項-三重項消滅 / 項間交差

Outline of Final Research Achievements

Triplet-triplet annihilation upconversion (TTA-UC) is a photoenergy conversion technique that can function even with light intensities as low as sunlight. If high UC quantum yields are achieved in solid-state samples, it is expected to improve the efficiency of solar-driven devices such as solar cells and photocatalysis. In this study, we attempted a measurement-driven approach to address this issue. Specifically, we applied spatially-resolved analysis based on emission spectromicroscopy to organic-organic/organic-inorganic composite microcrystals exhibiting TTA-UC emission. By precisely evaluating the photon detection efficiency of TTA-UC apparatus using single molecule measurements, the amounts of sensitizer/annihilator, the time constants and quantum yields of triplet energy transfer between sensitizer and annihilator in the microcrystals were successfully visualized for the first time.

Free Research Field

光物理化学

Academic Significance and Societal Importance of the Research Achievements

高効率かつ太陽光強度で機能するフォトンアップコンバージョン（PUC）固体材料の開発は、PUCにおける最重要課題の一つである。本研究では、顕微発光分光計測に基づく空間分解分析を、PUC現象を示す有機複合結晶や有機-無機複合結晶に適用することにより、微結晶中における増感剤と消滅体の存在量やPUCに関わる素過程の時定数・効率の空間不均一性を可視化する方法論を確立した。このような評価手法は、PUC固体内で起こるPUCの微視的理解を深化させる（＝学術的意義）だけでなく、より優れたPUC固体系の開発を促進し、太陽駆動デバイスの高効率化やセンサーへの応用へと繋がっていくこと（＝社会的意義）が期待される。