【Adv.Mater.】华东理工大学马骧、丁兵兵|实现54.9%发光效率与2380%拉伸率：微相工程化柔性余辉材料取得突破

文章标题： Harmonizing High Phosphorescence Efficiency and Stretchability in Flexible Afterglow Materials Through Microphase Engineering

通讯作者： Bingbing Ding, Xiang Ma

文章链接： https://doi.org/10.1002/adma.73314

文章概要

在这篇发表于《Advanced Materials》的研究论文中，研究团队针对有机超长室温磷光（OURTP）材料在柔性电子领域面临的发光效率与机械柔韧性之间的矛盾，提出了一种创新的微相工程化策略。通过将电荷转移型磷光客体冠烯（CE）引入苯乙烯-异戊二烯-苯乙烯嵌段共聚物（SIS）基质中，成功构建了一种既具有高效发光性能又具备超强拉伸性的复合材料。该研究不仅为解决聚合物基质中三线态激子稳定与分子链运动性之间的冲突提供了新思路，也展示了该材料在智能穿戴、防伪监测及生物抗菌等领域的广泛应用潜力。

Organic amorphous flexible ultralong afterglow materials developed via microphase engineering (a) and exciton recombination (b). ISC: intersystem crossing; RISC: reverse ISC; ET: energy transfer.

引言

有机超长室温磷光材料因其独特的光物理性质，在防伪、成像和显示等领域展现出巨大的应用前景。然而，实现高性能的柔性余辉材料一直是一个巨大挑战。三线态激子的稳定通常需要极端刚性的环境以抑制非辐射跃迁，但这往往会导致材料脆性大、缺乏弹性；而为了追求高拉伸性，材料往往需要具备较强的分子链流动性，这又会严重削弱磷光效率。传统的物理掺杂或简单的化学改性往往难以平衡这两者，且容易出现相分离和发光不均的问题。为了突破这一瓶颈，研究人员利用嵌段共聚物的微相分离特性，试图在同一纳米结构中同时实现“刚性限域”与“柔性支撑”。

(a) Photographic image series of SIS@CE under continuous 365 nm UV light irradiation with the power density of 18.5 mW/cm2 (top) and after ceasing irradiation (bottom); (b) Mechanism of photoactivated OURTP: oxygen consumption and photo-induced exciton accumulation (EA) in the film, CR: charge recombination; 3LE: triplet locally excited state.; The photoluminescence spectra of SIS@CE under (c) sustaining UV light irradiation (inset: Commission Internationale de l'Éclairage (CIE)-1931 coordinate) and (d) after ceasing irradiation (λex = 360 nm); (e) Time-dependent normalized phosphorescence intensity of SIS@CE under UV irradiation with different power densities; (f) The RTP decay curves at 560 nm of SIS@CE under sustaining UV light irradiation; (g) The phosphorescence intensity at 560 nm of SIS@CE upon alternating UV light irradiation for 10 s and ceasing UV irradiation for 30 s; (h) RTP Quantum yield and lifetimes of SIS@CE films with different doping mass ratios after UV irradiation.

主要实验及结论

研究团队首先通过溶剂挥发法制备了不同比例的SIS@CE薄膜。实验发现，在365 nm紫外光照射下，该材料表现出显著的光活化OURTP行为。随着照射时间的增加，溶解氧被消耗且激子不断积聚，使得磷光强度和寿命大幅提升。其中，0.1 wt.%掺杂浓度的薄膜表现最为优异，光活化后的磷光量子产率高达54.9%，寿命达到6.26秒，即便在停止照射60秒后，肉眼仍可清晰观察到绿色的长余辉。

(a) Jablonski diagram for SIS@CE film, CT: charge transfer; CS: charge separation; CR: charge recombination; 1LE: singlet locally excited state; 3LE: triplet locally excited state; ISC: intersystem crossing; 1CT&3CT: charge transfer state; (b) Time-resolved µs transient absorption spectrum of SIS@CE; (c) Kinetic decay curves of 1LED (445 nm), 3LED (500 nm) and 1CT&3CT (525 nm); Transient absorption spectrum of 0.1 wt.% SIS@CE at different time scales from 2.9 to 3.6 ps (d) and from 3.8 ps to 2.9 µs (e); (f) SAXS of 0.1 wt.% SIS@CE film, inset image of TEM images stained with osmium tetroxide (g) and grayscale analysis (h).

(a) Comparison of elongation, RTP lifetime and RTP QY between SIS@CE and the other reported materials; (b) Weight lifting and afterglow images of the SIS@CE film; (c) Cyclic strain-stress curves of SIS@CE at 600% strain over 40 cycles, inset: images of SIS@CE film after 40 stretched cycles; (d) SIS@CE images subjected to external tension for 2300% strain and the afterglow of different stress regions; (e) The relationship between afterglow intensity and strain of SIS@CE with afterglow attenuation images under different strains.

在机理研究方面，结构表征证明了SIS基质中存在高度有序的微相分离结构。刚性的聚苯乙烯（PS）微区作为“限域空间”，有效地固定了发光客体，并通过电荷转移效应稳定了三线态激子，从而保证了高效率的磷光发射；而柔性的聚异戊二烯（PI）相则充当了“缓冲骨架”，赋予了材料宏观上的超强韧性。瞬态吸收光谱进一步证实了长寿命电荷转移态的存在，这种状态作为能量缓冲阶梯，显著提高了系间窜越效率。

(a,b) Melt-molded SIS@CE filaments with photoactive weaving exhibit UV-triggered green OURTP under 365 nm irradiation; (c) Ultra-thin luminous SIS@CE yarns; (d) Schematic illustration of the inactivation of E. coli; (e) E. coli colony growth images and coculture of blank control group and SIS@CE under 405 nm blue light irradiation; (f) Solar-activated OURTP with high visible-light transmittance; (g) Solar-activated luminescent warning films for automobiles; (h) Luminescent photograph of SIS@CE taken after UV light irradiation after soaking in different solution environments over a month.

机械性能测试结果令人惊叹，该材料的断裂伸长率高达2380.5%，并展现出优异的疲劳抗性，在600%应变下循环40次后仍能保持结构完整。更有趣的是，研究发现该材料具有应力响应发光特性：随着拉伸倍数的增加，基质的局部刚性受到扰动，导致余辉强度和寿命出现可量化的衰减。此外，由于三线态激子介导的单线态氧产生能力，该材料还表现出极佳的光动力抗菌效果，对大肠杆菌的杀灭率超过99.98%。

总结及展望

本研究通过微相工程化策略，成功开发出一种兼具高量子产率、超长余辉寿命和极限拉伸性能的柔性有机磷光材料。通过精准调控嵌段共聚物的纳米相区，实现了发光功能与机械柔韧性的完美解耦。这种材料不仅可以通过熔融加工制备成超细发光纤维（直径仅50微米），应用于智能纺织品和可穿戴设备，还能作为环境友好的太阳光驱动警示贴片用于汽车安全。该策略具有普适性，为未来开发多功能、高性能的柔性光电材料开辟了全新的设计路径，有望在人体健康监测、智能感知及柔性显示等前沿领域发挥重要作用。