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

Abstract

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.

On-demand modulating afterglow color of water-soluble polymers through phosphorescence FRET for multicolor security printing

“…Current efforts in this field have been mainly focused on constructing various molecules and manipulating their lifetimes and quantum efficiency (13)(14)(15), while limited considerations have been devoted to developing water-soluble full-color OURTP emitters, let alone demonstrating their viable applications in multifarious security printing. To modulate the organic afterglow color, a variety of strategies have been proposed, including regulating material compositions and stacking motifs (16), using synergetic emission from molecular and aggregated phosphorescence (17,18), as well as incorporating multiple emission centers (19,20), and using triplet(T 1 )-singlet (S 1 ) energy transfer (21,22). Despite the flourishing advancements in OURTP materials showing color-tunable emission, there is still a daunting challenge to rationally realize water-soluble full-color OURTP materials with rational manipulation of afterglow colors, which are of great significance for environmental-friendly and multicolor security printing.…”

Persistent room temperature phosphorescence films based on star-shaped organic emitters

“…6,36–42 However, the poor reproducibility, processability, and flexibility of these crystal-based materials will greatly hinder their further development. 14,43–45 Especially, the preparation of their thin films is always a critical and challenging task, while thin films with desirable optical properties are highly desired for many important practical applications. 14,43,46,47 In addition, in film states, the active vibration/diffusion motions of phosphors may quench the long-live triplet excitons.…”

“…14,43–45 Especially, the preparation of their thin films is always a critical and challenging task, while thin films with desirable optical properties are highly desired for many important practical applications. 14,43,46,47 In addition, in film states, the active vibration/diffusion motions of phosphors may quench the long-live triplet excitons. 43 Although several blend films of small molecular phosphors with rigid polymer matrices or host molecules have been reported, 3,8,29–31,48–51 it is hard to control the homogeneity of these doped films due to inevitable phase separation in two-component systems 52 .…”

“…14,43,46,47 In addition, in film states, the active vibration/diffusion motions of phosphors may quench the long-live triplet excitons. 43 Although several blend films of small molecular phosphors with rigid polymer matrices or host molecules have been reported, 3,8,29–31,48–51 it is hard to control the homogeneity of these doped films due to inevitable phase separation in two-component systems 52 . Therefore, fabrication of single-component RTP films should be more convenient.…”

Room temperature tunable multicolor phosphorescent polymers for humidity detection and information encryption

“… 26 Tang et al presented wide-color ranged and persistent RTP from amorphous films by embedding electron-rich organic phosphor into electron-deficient matrix polyacrylonitrile. 27 Despite numerous advances, developing advanced RTP materials still remains challenging in several aspects, for example, most of polymer-based RTP materials just emit a single color. If the luminescent color can vary with external stimulation, it will effectively expand the application range of materials and meet the new development requirements of organic functional materials.…”