Ultrafast photoexcited dynamics of Cu(I) complexes with thermally activated delayed fluorescence in solid-state thin layers

2022 Fiscal Year Final Research Report

• Project/Area Number: 20K05446
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 32020:Functional solid state chemistry-related
• Research Institution: University of Toyama
• Principal Investigator: NOZAKI Koichi 富山大学, 学術研究部理学系, 教授 (20212128)
• Project Period (FY): 2020-04-01 – 2023-03-31
• Keywords: 銅錯体 / 熱活性遅延蛍光 / ヤーンテラー構造変形 / 時間分解蛍光寿命測定 / フェムト秒アップコンバージョン / 固体膜 / MLCT / XLCT

Outline of Final Research Achievements

Intensely emitting molecules such as copper(I) complexes often show environment-dependent emission properties in solid states. In this work, we developed a femtosecond time-resolved emission measurement system for direct observation of ultrafast photorelaxation dynamics in solid films, such as exciton diffusion. intersystem crossing, and structural relaxation in excited states.
Halogen-bridged copper(I) complexes with thermally activated delayed fluorescence from XLCT/MLCT mixed states undergo no structural relaxation in single crystals. Meanwhile, in vapor-deposited films of the copper(I) complex, it has been revealed that a transition from XLCT to MLCT occurred with a change in coordination structure of the copper ion and that the broadening of emission spectra in the halogen-bridged copper(I) complexes depends on rigidity of surrounding media.

Free Research Field

光化学

Academic Significance and Societal Importance of the Research Achievements

本研究において、固体薄膜中でのフェムト秒時間分解発光測定を可能にする装置を開発し、発光素子に近い固相状態での励起状態のエネルギーの緩和過程やエキシマー形成などの過程を明らかにしたことは学術的に意義がある。また、熱活性遅延蛍光性のハロゲン架橋銅(I)錯体の発光色が光励起後動的に変化することを明らかにしたことは、固相の剛性によって発光素子の発光物性を制御できる可能性を示唆するものである。