Micropatterned Scintillator Films With Engineered <scp>C</scp> s ₃ <scp>C</scp> u ₂ <scp>I</scp> ₅ / <scp>C</scp> s <scp>C</scp> u ₂ <scp>I</scp> ₃ Nanocrystals for Low‐Crosstalk X‐Ray Imaging at

The spatial resolution of X‐ray imaging is often limited by radioluminescence scattering, which is exacerbated in thick scintillators and unpatterned films due to lateral light spreading. Commercial scintillators such as cesium iodide and gadolinium oxysulfide, although hundreds of micrometers thick to ensure efficient X‐ray absorption, still suffer from optical crosstalk, complicated fabrication, and high production costs. To overcome these challenges, we report a novel micropatterned lead‐free green and sustainable 1D Cu‐based perovskite nanocrystals scintillator film. Specifically, polyethylene glycol‐coated CsCu 2 I 3 nanocrystals are used to achieve improved quantum yield and precise thickness control, facilitated by the flexibility and compatibility of polyethylene glycol with the Cu‐based nanocrystals. During polyethylene glycol treatment, zero‐dimensional Cs 3 Cu 2 I 5 nanocrystals transform into 1D CsCu 2 I 3 nanocrystals, occurring, accompanied by a pronounced redshift in emission, enabling the fabrication of yellow‐emitting scintillator films. Further, photolithographic techniques are used to fabricate patterned substrates with varying pattern sizes and thicknesses, which were subsequently filled with polyethylene glycol‐coated CsCu 2 I 3 nanocrystals via a hot‐press method. The optimized micropatterned scintillator film effectively suppressed optical crosstalk and delivered enhanced spatial resolution under a clinically relevant tube voltage (80 kVp), outperforming unpatterned counterparts. X‐ray imaging at such high voltage conditions has rarely been demonstrated using copper halide materials. This strategy highlights a practical route toward clinically relevant, scalable, and high‐resolution scintillator films for advanced X‐ray imaging.