Organic Cation Modulation in Hybrid Zirconium Halides for High‐Performance Flexible X‐ray Imaging

Exploiting novel materials featuring high‐quality zero‐dimensional structure, remarkable lattice stability, and minimal defects represents an efficacious strategy for enhancing the detection performance of X‐ray scintillators. Here, we design and synthesize two novel, lead‐free, zirconium‐based zero‐dimensional organic‐inorganic hybrid metal halides (OIMHs), C14H40N4ZrCl8 and C6H16N2ZrCl6. Based on the steric hindrance effect of organic cations, the distance between [ZrCl6]2‐ polyhedra was designed and the electronic coupling interactions among polyhedra were adjusted, thus precisely engineering excellent zero‐dimensional materials. Simultaneously, the stronger N‐H+···Cl‐ (interstitial) bond is introduced to avoid structural instabilities and more defects due to the bigger organic cation in C14H40N4ZrCl8. As expected, C14H40N4ZrCl8 exhibits more remarkable luminescence behavior compared to C6H16N2ZrCl6 when excited by UV light and X‐rays. The photophysics process involving self‐trapped excitons and defects is elaborately expounded using first‐principles calculations, luminescence properties, and stabilities. Finally, a flexible and large‐area scintillation screen with a size of up to 200×100 mm2 based on C14H40N4ZrCl8 is fabricated and attains a high spatial resolution of 21.35 lp mm‐1 and a lower limit of detection of 2.270 μGyair s‐1, outperforming the resolution of most blue‐emitting scintillation screens. These results imply that the zirconium‐based OIMHs possess significant potential applications for medical diagnostics, security scanning, and non‐destructive testing.