Wang Guangming, Chen Xuefeng, Zeng Ying, Li Xun, Wang Xuepu, Zhang Kaka
State Key Laboratory of Organometallic Chemistry and Shanghai Hongkong Joint Laboratory in Chemical Synthesis, Key Laboratory of Synthetic and Self-Assembly Chemistry for Organic Functional Molecules, Shanghai Institute of Organic Chemistry, University of Chinese Academy of Sciences, Chinese Academy of Sciences, 345 Lingling Road, Shanghai 200032, People's Republic of China.
J Am Chem Soc. 2024 Sep 11;146(36):24871-24883. doi: 10.1021/jacs.4c05531. Epub 2024 Aug 30.
Organic room-temperature phosphorescence (RTP) and afterglow materials hold great potential for various applications, but there remain inherent trade-offs between the afterglow efficiency and the lifetime. Here, we propose a dual-mechanism design strategy, leveraging the RTP or thermally activated delayed fluorescence (TADF) mechanism for a high afterglow efficiency and the organic long-persistent luminescence (OLPL) mechanism for a prolonged afterglow duration. The intramolecular charge transfer (ICT)-type difluoroboron β-diketonate molecules with a large S dipole moment are doped as the luminescent component into the organic matrix with a large dipole moment, and a series of TADF-type afterglow materials can be achieved with an afterglow efficiency of up to 88.7% and an afterglow lifetime of 200 ms. To prolong the afterglow duration, an electron donor is introduced as the third component to generate traps and facilitate charge separation. The obtained materials exhibit a dual afterglow mechanism, first exhibiting a TADF/RTP afterglow with an afterglow efficiency of up to 50.9%, followed by an hours-long OLPL afterglow emission with an afterglow efficiency of up to 13.1%. Further investigations reveal that an appropriate heavy-atom effect can facilitate the intersystem crossing process, which can promote the charge separation process and thus improve the OLPL afterglow performance. Additionally, rare-earth upconversion materials are introduced into OLPL materials to enable their near-infrared excitation properties, showcasing their potential applications in bioimaging.
有机室温磷光（RTP）和余辉材料在各种应用中具有巨大潜力，但在余辉效率和寿命之间仍存在内在的权衡。在此，我们提出一种双机制设计策略，利用RTP或热激活延迟荧光（TADF）机制实现高余辉效率，利用有机长余辉发光（OLPL）机制实现长余辉持续时间。将具有大S偶极矩的分子内电荷转移（ICT）型二氟硼β-二酮分子作为发光组分掺杂到具有大偶极矩的有机基质中，可实现一系列TADF型余辉材料，其余辉效率高达88.7%，余辉寿命为200毫秒。为了延长余辉持续时间，引入电子供体作为第三组分以产生陷阱并促进电荷分离。所获得的材料表现出双余辉机制，首先表现出TADF/RTP余辉，余辉效率高达50.9%，随后是长达数小时的OLPL余辉发射，余辉效率高达13.1%。进一步研究表明，适当的重原子效应可促进系间窜越过程，这可促进电荷分离过程，从而改善OLPL余辉性能。此外，将稀土上转换材料引入OLPL材料以实现其近红外激发特性，展示了它们在生物成像中的潜在应用。
