Zhang Yongfeng, Chen Xiaohong, Xu Jianrong, Zhang Qinglun, Gao Liang, Wang Zhonghao, Qu Lunjun, Wang Kaiti, Li Youbing, Cai Zhengxu, Zhao Yanli, Yang Chaolong
School of Materials Science and Engineering, Chongqing University of Technology, Chongqing 400054 China.
Beijing Key Laboratory of Construction Tailorable Advanced Functional Materials and Green Applications, School of Materials Science & Engineering, Beijing Institute of Technology, Beijing 100081 China.
J Am Chem Soc. 2022 Apr 6;144(13):6107-6117. doi: 10.1021/jacs.2c02076. Epub 2022 Mar 22.
Long-lived organic room-temperature phosphorescence (RTP) has sparked intense explorations, owing to the outstanding optical performance and exceptional applications. Because triplet excitons in organic RTP experience multifarious relaxation processes resulting from their high sensitivity, spin multiplicity, inevitable nonradiative decay, and external quenchers, boosting RTP performance by the modulated triplet-exciton behavior is challenging. Herein, we report that cross-linked polyphosphazene nanospheres can effectively promote long-lived organic RTP. Through molecular engineering, multiple carbonyl groups (C═O), heteroatoms (N and P), and heavy atoms (Cl) are introduced into the polyphosphazene nanospheres, largely strengthening the spin-orbit coupling constant by recalibrating the electronic configurations between singlet (S) and triplet (T) excitons. In order to further suppress nonradiative decay and avoid quenching under ambient conditions, polyphosphazene nanospheres are encapsulated with poly(vinyl alcohol) matrix, thus synchronously prompting phosphorescence lifetime (173 ms longer), phosphorescence efficiency (∼12-fold higher), afterglow duration time (more than 20 s), and afterglow absolute luminance (∼19-fold higher) as compared with the 2,3,6,7,10,11-hexahydroxytriphenylene precursor. By measuring the emission intensity of the phosphorescence, an effective probe based on the nanospheres is developed for visible, quantitative, and expeditious detection of volatile organic compounds. More significantly, the obtained films show high selectivity and robustness for anisole detection (7.1 × 10 mol L). This work not only demonstrates a way toward boosting the efficiency of RTP materials but also provides a new avenue to apply RTP materials in feasible detection applications.
长寿命有机室温磷光（RTP）因其出色的光学性能和卓越的应用而引发了广泛的探索。由于有机RTP中的三重态激子具有高灵敏度、自旋多重性、不可避免的非辐射衰减以及外部猝灭剂等因素，导致其经历多种弛豫过程，因此通过调节三重态激子行为来提高RTP性能具有挑战性。在此，我们报道交联聚磷腈纳米球可以有效地促进长寿命有机RTP。通过分子工程，多个羰基（C═O）、杂原子（N和P）以及重原子（Cl）被引入到聚磷腈纳米球中，通过重新校准单重态（S）和三重态（T）激子之间的电子构型，大大增强了自旋 - 轨道耦合常数。为了进一步抑制非辐射衰减并避免在环境条件下猝灭，聚磷腈纳米球被聚乙烯醇基质包裹，从而与2,3,6,7,10,11 - 六羟基三亚苯前驱体相比，同步提高了磷光寿命（延长173 ms）、磷光效率（高约12倍）、余辉持续时间（超过20 s）和余辉绝对亮度（高约19倍）。通过测量磷光的发射强度，开发了一种基于纳米球的有效探针，用于可见、定量和快速检测挥发性有机化合物。更重要的是，所获得的薄膜对苯甲醚检测显示出高选择性和稳健性（7.1×10 mol L）。这项工作不仅展示了提高RTP材料效率的方法，还为将RTP材料应用于可行的检测应用提供了新途径。
