Vertically‐Structured Large‐Scale Cs ₃ Cu ₂ I ₅ : Tl Scintillator Film: A New Choice for Commercial Flat Panel Detectors

For decades, the performance of x‐ray flat‐panel detectors (FPDs) has been constrained by the inherent trade‐offs between sensitivity, resolution, and imaging speed in conventional scintillators such as CsI:Tl and Gd 2 O 2 S (GOS). Overcoming these limitations through an almighty scintillator remains a critical challenge, hindered by the difficulty of discovering new high‐performance materials and complexities of their large‐scale fabrication. Cs 3 Cu 2 I 5 :Tl has been recently recognized as a promising candidate, while its practical application has been restricted by challenges in thick‐film fabrication and a lack of appropriate imaging demonstrations. In this work, we report the fabrication of large‐area (43 × 43 cm 2 ), vertically oriented Cs 3 Cu 2 I 5 :Tl thick film (> 300 µm) directly on commercial thin‐film transistor (TFT) panels using a single‐source evaporation method. The resulting integrated FPD achieves a spatial resolution of 3.7 lp mm −1 (unmagnified) with negligible afterglow (<0.3%@5 ms). Leveraging the high photo‐response non‐uniformity (PRNU, 0.16%), minimal lag, and a spatiotemporal transformer‐based machine‐learning framework, high quality and high‐speed imaging and computed tomography are demonstrated. The balanced performance, high sensitivity, remarkable stability under ambient conditions and high‐energy x‐ray irradiation, and the scalable fabrication method presented establish Cs 3 Cu 2 I 5 :Tl thick film as a compelling next‐generation scintillator for advanced FPD applications.