Bond‐Mode Engineering in Copper(I) Halides: From Excitation‐Dependent Luminescence to High‐Resolution X‐Ray Imaging Screens

ABSTRACT Copper(I)‐based halides are promising for X‐ray detection due to their excellent scintillation efficiency and solution processability. However, the structure–property relationship remains elusive, and their practical viability for X‐ray imaging is largely unverified. In this work, we employ a bond‑mode control strategy to synthesize two compounds from the same amine precursor: ionic (4‑ATHP) 2 CuI 3 and coordinative (4‑ATHP) 4 Cu 4 I 4 (4‐ATHP = 4‐Aminotetrahydropyran), providing a model system to study their photophysics and underlying mechanism. (4‑ATHP) 2 CuI 3 adopts a unique 1D crystal structure with alternating arrangement of Cu 2 I 6 dimers, which shows excitation‑dependent dual emissions. Experimental and calculation results indicate that the dual emissions originate from the Cu 2 I 6 dimer with a different Cu─Cu bond length. In contrast, the (4‑ATHP) 4 Cu 4 I 4 shows single emission centered at 635 nm, in which the organic component contributes to the excited state. The ionic (4‑ATHP) 2 CuI 3 achieves a much higher light yield (55 923 photons/MeV) than that of the coordinative counterpart (31 866 photons/MeV). Furthermore, a large‑area flexible film (15 × 20 cm 2 ) based on (4‑ATHP) 2 CuI 3 delivers a spatial resolution of 20 lp/mm. Critically, integrating this film into a CMOS imager demonstrates superior dynamic imaging without afterglow, outperforming the commercialized CsI: Tl screen. This study not only deciphers the bond‑mode‑dependent photophysics but also validates a commercial‑grade scintillator, paving the way for high‑performance X‑ray imaging materials.