Cross-Linked Polyphosphazene Nanospheres Boosting Long-Lived Organic Room-Temperature Phosphorescence

Yongfeng Zhang; Xiaohong Chen; Jianrong Xu; Qinglun Zhang; Liang Gao; Zhonghao Wang; Lunjun Qu; Kaiti Wang; Youbing Li; Zhengxu Cai; Yanli Zhao; Chaolong Yang

doi:10.1021/jacs.2c02076

Cross-Linked Polyphosphazene Nanospheres Boosting Long-Lived Organic Room-Temperature Phosphorescence

J Am Chem Soc. 2022 Apr 6;144(13):6107-6117. doi: 10.1021/jacs.2c02076. Epub 2022 Mar 22.

Authors

Yongfeng Zhang¹, Xiaohong Chen¹, Jianrong Xu¹, Qinglun Zhang¹, Liang Gao¹, Zhonghao Wang¹, Lunjun Qu¹, Kaiti Wang¹, Youbing Li¹, Zhengxu Cai², Yanli Zhao³, Chaolong Yang^{1

4}

Affiliations

¹ School of Materials Science and Engineering, Chongqing University of Technology, Chongqing 400054 China.
² Beijing Key Laboratory of Construction Tailorable Advanced Functional Materials and Green Applications, School of Materials Science & Engineering, Beijing Institute of Technology, Beijing 100081 China.
³ Divisions of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, Singapore 637371 Singapore.
⁴ Guangdong Provincial Key Laboratory of Luminescence from Molecular Aggregates, South China University of Technology, Guangzhou 510640, China.

PMID: 35316063
DOI: 10.1021/jacs.2c02076

Abstract

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_n) and triplet (T_n) 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^-4 mol L^-1). 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.