High‐Temperature Organic Scintillation and X‐Ray Imaging Enabled by a Brominated Pyrazine Phosphor

Purely organic scintillators provide lightweight and solution‐processable alternatives to conventional inorganic materials, but their applications at elevated temperatures remain challenging due to severe thermal quenching and inefficient X‐ray energy conversion. Here, a brominated pyrazine phosphor, DCPPBr , is developed to integrate thermally robust red phosphorescence, efficient X‐ray scintillation, and high‐temperature X‐ray imaging. Bromine incorporation into the planar π‐conjugated framework simultaneously enhances spin‐orbit coupling and X‐ray attenuation, while halogen bonding, hydrogen bonding, and π–π interactions construct a rigid supramolecular lattice. These intermolecular interactions effectively suppress thermally activated nonradiative decay, allowing DCPPBr to maintain red phosphorescence and X‐ray‐excited radioluminescence up to 423 K. The resulting scintillator exhibits an X‐ray scintillation light yield of 25,459 photons MeV −1 and a low detection limit of 424 nGy s −1 . Moreover, a transparent DCPPBr /epoxy scintillator screen with only 1 wt% loading achieves X‐ray imaging with a spatial resolution of approximately 10 lp mm −1 at room temperature and retains 7 lp mm −1 resolution at 373 K, enabling clear visualization of microchip structures under high‐temperature conditions. Beyond X‐ray excitation, DCPPBr also exhibits red phosphorescence from ultraviolet to blue‐light excitation. This work provides new insights into purely organic scintillators for high‐temperature X‐ray imaging.