Aggregation-Induced Long-Lived Phosphorescence in Nonconjugated Polyurethane Derivatives at 77 K,Macromolecules

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Aggregation-Induced Long-Lived Phosphorescence in Nonconjugated Polyurethane Derivatives at 77 K
Macromolecules ( IF 5.1 ) Pub Date : 2018-05-23 00:00:00 , DOI: 10.1021/acs.macromol.8b00715
Nan Jiang ₁ , Guang-Fu Li ₁ , Bao-Hua Zhang ₂ , Dong-Xia Zhu ₁ , Zhong-Min Su ₁ , Martin R. Bryce ₃

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Achieving long-persistent phosphorescence in polymers is a challenge even at low temperatures. In this work, long-persistent phosphorescence (>1 s) is observed in nonconjugated polyurethane derivatives at 77 K, which is among the longest reported phosphorescent lifetimes for an organic polymer. The mechanism for this unusual behavior has been shown by steady-state photophysical characterization and time-resolved emission spectra to arise from the formation of intra- and/or intermolecular carbonyl clusters at low temperature. The lifetime of long-persistent phosphorescence is increased by the introduction of an aromatic monomer into the nonconjugated polyurethane chains. This is attributed to intra- and/or intermolecular n−π* transitions from electron-rich carbonyl groups to the conjugated aromatic units, thereby enhancing the intersystem crossing rate. Coating an ultraviolet InGaAsN light-emitting diode with a polyurethane derivative as the emitter gives cryogenic afterglow with long-persistent phosphorescence that is observed for up to 7 s with the naked eye.

中文翻译：

非共轭聚氨酯衍生物中77 K的聚集诱导的长寿命磷光

即使在低温下，在聚合物中实现持久的磷光也是一个挑战。在这项工作中，在非共轭聚氨酯衍生物中在77 K处观察到长时间持久的磷光（> 1 s），这是有机聚合物报道的最长的磷光寿命之一。稳态光物理特征和时间分辨发射光谱已证明这种异常行为的机理是由于低温下分子内和/或分子间羰基簇的形成而引起的。通过将芳香族单体引入非共轭聚氨酯链中，可以延长长时间持续磷光的寿命。这归因于从富电子羰基到共轭芳族单元的分子内和/或分子间n-π*跃迁，从而提高了系统间的交叉速率。在紫外InGaAsN发光二极管上涂上聚氨酯衍生物作为发射体，可产生深低温余辉，并具有长期持续的磷光，用肉眼观察到的时间长达7 s。

更新日期：2018-05-23

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