Tailoring Noncovalent Interactions to Activate Persistent Room‐Temperature Phosphorescence from Doped Polyacrylonitrile Films

• Published in: Advanced functional materials 2021-08, Vol.31 (32), p.n/a
• Main Authors: Wu, Hongzhuo, Wang, Deliang, Zhao, Zheng, Wang, Dong, Xiong, Yu, Tang, Ben Zhong
• Format: Article
• Language: English
• Subjects: Biomedical materials; Chemical bonds; Dispersion; Doped films; doped polyacrylonitrile films; Electrons; Hydrogen bonding; Materials science; noncovalent interactions; Optoelectronics; Phosphorescence; Phosphors; Polyacrylonitrile; Polymethyl methacrylate; Polystyrene resins; room‐temperature phosphorescence; ultralong lifetime; Water resistance
• ISSN: 1616-301X; 1616-3028
• DOI: 10.1002/adfm.202101656

Organic phosphors exhibiting room‐temperature phosphorescence (RTP) in amorphous phase are good candidates for optoelectronic and biomedical applications. In this proof‐of‐concept work, a rational strategy to activate wide‐color ranged and persistent RTP from amorphous films by embedding electron‐rich organic phosphor into electron‐deficient matrix polyacrylonitrile (PAN) is presented. Through tailoring noncovalent interactions between the electron‐deficient PAN matrix and electron‐rich organic phosphors, an ultralong lifetime of 968.1 ms is obtained for doped film TBB‐6OMe@PAN. Control experiments conducted on the polymers polymethyl methacrylate (PMMA) and polystyrene (PS) without electron‐withdrawing groups, and organic phosphors containing electron‐withdrawing groups indicate that the persistent RTP of doped films may be triggered by strong electrostatic interactions between electron‐deficient PAN and electron‐rich organic phosphor. Further theoretical calculations including electrostatic potential distributions, binding energies, and energy decomposing analysis demonstrate that both electrostatic and dispersion interactions between electron‐deficient PAN and electron‐rich organic phosphor are responsible for the activation of persistent RTP of doped films. In addition, the doped film TBB‐6OMe@PAN still maintains brightness even after soaking in water for 12 weeks. This excellent water resistance not only is favorable for future applications but also demonstrates an advantage of electrostatic and dispersion interactions over hydrogen bonding interactions. An instructive design rule based on the tuning of intermolecular noncovalent interactions between the electron‐deficient polyacrylonitrile (PAN) matrix and electron‐rich organic phosphors to trigger persistent room‐temperature phosphorescence (RTP) of amorphous films is presented. Both electrostatic and dispersion interactions between the PAN matrix and electron‐rich organic phosphors contribute to the activation of persistent RTP of doped PAN films.