Establishing Amorphous Organoeuropium Complex Films Through Solvent‐Triggered Self‐Stacking

ABSTRACT Europium‐based scintillators are attractive for X‐ray imaging because of their high color purity, large Stokes shift, and tunable coordination chemistry. However, the fabrication of large‐area, mechanically compliant scintillation films typically relies on polymer matrices or high‐temperature processing, which inherently dilute the scintillator phase, increase optical scattering, and complicate direct integration with detector backplanes. Here, we report a solvent‐triggered self‐stacking strategy for constructing matrix‐free amorphous scintillation films directly from ternary organoeuropium complexes. Using Eu(NTA) 3 (TPPO) 2 (NTA = 4,4,4‐trifluoro‐1‐(2‐naphthyl)‐1,3‐butanedione, TPPO = triphenylphosphine oxide) dissolved in dichloromethane as a model system, we show that solvent evaporation drives a solution‐to‐film transition, yielding dense and uniform Eu(NTA) 3 (TPPO) 2 films with characteristic Eu 3+ red emission. Spectroscopic analyses and theoretical calculations indicate that the strong emission and amorphous packing are induced by strong intramolecular interaction but weak intermolecular interaction. The resulting Eu(NTA) 3 (TPPO) 2 films can be deposited on both rigid and flexible substrates, exhibit intense radioluminescence, sensitive low‐dose X‐ray response, and high‐resolution X‐ray imaging capability, and can be directly integrated with commercial amorphous‐silicon flat‐panel detectors. This work establishes a general strategy for assembling molecular organoeuropium complexes into matrix‐free film scintillators, expanding the materials platform for flexible and in situ X‐ray imaging.