光响应室温磷光材料因其广阔的应用前景而受到越来越多的关注。迄今为止，人们仍难以获得兼具高效率和长寿命的磷光材料。蓝光和红光材料的缺乏在很大程度上限制了室温磷光材料的应用。
近日，武汉大学李振教授和天津大学杨杰副教授等人在Science China Materials发表研究论文，报导了一种构筑高效光诱导室温磷光材料的新策略，即通过具有n-π*跃迁的吩噻嗪和以π-π*跃迁主导的多环芳烃相结合，来维持磷光分子的高效率和长寿命。
1) 当把这些材料掺杂进聚合物基体中时，由于多环芳烃的π共轭结构变化，所获得的掺杂体系可以获得红-绿-蓝（RGB）发射色，其中，PTri@PVP的室温磷光性能最好，磷光量子产率为20.73 %，寿命长达819毫秒。2) 在停止紫外线照射后，该体系会出现由绿变蓝的随时间变化的磷光余辉，这源于两种不同的分子构象，并可通过热刺激进一步调节。3) 基于这些材料，成功实现了其包括丝网印刷、多色图案和多维信息加密在内的多种防伪应用。Figure 1. Schematic diagram of photo-induced RTP system with high efficiency, long lifetime and tunable emission color. For this system, compounds PPh, PNap, PPhe, PTri and PPy acted as guest and PVP as host matrixes. Among them, PTri@PVP showed photo-induced dual RTP emissions for the existence of two conformations, which could be further regulated by thermal stimulus.Figure 2. (a) Photographs of PPhe@PVP, PPy@PVP and PTri@PVP before and after removal of 365 nm UV light excitation. (b–d) Time-resolved RTP spectra of PTri@PVP, PPhe@PVP and PPy@PVP. (e) CIE coordinate diagrams of the afterglow for PTri@PVP. (f) Phosphorescence lifetimes of PTri@PVP at different wavelengths. (g) Photo-induced RTP process of PTri@PVP. “UV OFF” represents the phosphorescence spectrum of the moment the excitation is stopped.Figure 3. (a, b) Potential surface scanning calculations for compounds PPhe and PTri at S0 state, where the torsion angle between phenothiazine and phenanthrene/triphenylene served as the scanning coordinate. (c, d) Schematic of the relative energies of compounds PPhe and PTri with excited state relaxation. (e, f) Calculated energy levels and SOC constants based on the configurations of T1 state for eq-PPhe, eq-PTri, and ax-PTri. (g, h) NTOs of eq-PPhe, eq-PTri and ax-PTri in T1 state.Figure 4. (a) Application of PPhe@PVP in screen printing. (b) Erasable pattern application based on PPy@PVP and PTri@PVP, in which white phosphorescence pattern produced by the spectral complementarity of PPy@PVP and PTri@PVP was achieved. (c) 3D programmable multi-information decoding.Jiayi Liang, Jie Yang, Yunsheng Wang, Mingda Shan, Zhenjiang Liu, Jia Ren, Manman Fang, Zhen Li. Efficient photo-induced RTP materials based on phenothiazine and polycyclic aromatic hydrocarbons: Tunable emission color and thermal stimulus response. Sci. China Mater. (2024).https://doi.org/10.1007/s40843-024-2983-x
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