在有机分子中增强的三倍三倍向上转换的机制
Changhae Andrew Kim1, Shicheng Hu1, Troy Van Voorhis1
1Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States.
The journal of physical chemistry. A
|August 16, 2023
概括
研究人员通过提高系统间交叉 (ISC) 速率,优化有机材料以实现高效的三倍三倍上转换 (TTU). 这一策略涉及调整分子结构以促进T2 → S1 ISC过程,从而提高TTU材料性能.
科学领域:
- 摄影化学和光物理
- 材料科学 材料科学 材料科学
- 计算化学计算化学
背景情况:
- 三倍三倍向上转换 (TTU) 对于提高有机材料的光采集效率至关重要.
- 有效的TTU依赖于两步旋转非保护过程 (T1 + T1 → T2 → S1),其中从T2到S1的系统间交叉 (ISC) 必须比内部转换 (IC) 到T1.1更快.
研究的目的:
- 通过使用时间依赖密度函数理论 (TDDFT) 研究有机材料中高效三倍三倍向上转换 (TTU) 的机制.
- 确定提高T2 → S1系统间交叉率 (ISC) 的策略,以提高TTU效率.
主要方法:
- 时间依赖密度函数理论 (TDDFT) 的计算被用来研究TTU机制.
- 分析的重点是T2 → S1 ISC和T2 → T1内部转换 (IC) 之间的竞争.
- 研究了分子修饰,包括替代组和重原子,对ISC和IC速率的影响.
主要成果:
- 有效的T2 → S1 ISC可以通过替换电子捐赠/提取组,扭曲分子几何或结合重原子来增强.
- 这些修改允许调整T2 → S1的ISC速率超过五个数量级,符合El-Sayed的规则.
- 由于能量差距大 (>0.5 eV),T2 → T1内部转换 (IC) 被显著抑制,确保了缓慢的IC速率.
结论:
- 调整T2 → S1系统间交叉点 (ISC) 是一种有效的策略,用于系统地改进三重三重升级 (TTU) 材料.
- 在T2和T1状态之间的巨大能量差距有效地抑制了内部转换,有利于所需的上升转换路径.
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