Coordinative Polyimides‐Ln3+ for Full‐Spectrum Luminescence with Applications in PLEDs and Acid‐Responsive Data Encryption

Abstract Controllable coordination and efficient sensitization of rare earth ions in polymer materials are key to achieving high‐performance optoelectronic polymers. By designing aromatic diamines, polyimides are synthesized with 1,10‐phenanthroline benzimidazole groups (PBG) in the polymer backbone. Utilizing the coordination between PBG and rare earth ions (Eu 3 ⁺, Tb 3 ⁺), polyimide‐rare earth complexes are formed and precisely characterized their structures. The unique coordination allows PBG to effectively sensitize Eu 3 ⁺, resulting in efficient, long‐lived red emission. Furthermore, PBG maintains excellent coordination with Eu 3 ⁺ in acidic environments, granting acid‐responsive color changes for data encryption. Importantly, PBG sensitization of Tb 3 ⁺ enabled full‐spectrum emission (CIE coordinates: (0.31, 0.35)) within a single rare earth‐polyimide complex, due to electron transfer among the ions, ligands, and polymer. This leads to the design of a multi‐layer PLED device with an optimal external quantum efficiency of 0.43% for white light emission (CIE coordinates: (0.28, 0.34)). Through comparative theoretical and experimental analysis, the photophysical behavior of these coordinated polyimides is explained and explored their photoluminescent and electroluminescent properties. This research integrates the advantages of rare earth elements and polyimides, creating novel luminescent polymers with diverse optical applications, providing a new strategy for designing luminescent coordination polymers.