Ultrabright X‑Ray Scintillators Enabled by Strong Exciton Confinement and Hierarchical Energy Funneling

Organic‐inorganic hybrid metal halides are promising X‑ray scintillators due to their tunable structures and strong X‑ray attenuation. However, inefficient energy transfer between organic ligands and metal halides severely limits exciton utilization, resulting in low brightness and poor imaging resolution. Herein, we present a design strategy that synergistically combines strong exciton confinement with hierarchical energy funneling in a Zn 2+ ‑doped hybrid material, producing the ultrabright scintillator (TPA) 2 Mn 0.88 Zn 0.12 Br 4 . This scintillator achieves a record relative light yield of 115,800 photons MeV −1 , surpassing its undoped counterpart by 103.9%, along with a near‑unity photoluminescence quantum yield of 99.5%, attributed to enhanced ligand‑to‑metal‑halide energy transfer and strongly confined excitons. When fabricated into a flexible scintillation film, it delivers an ultralow detection limit of 12.3 nGy air s −1 , high spatial resolution of 23.3 lp mm −1 in static imaging, and a 3D dynamic imaging capability at 25 frames s −1 . It also shows remarkable scintillation stability under high−dose X−ray radiation (maintaining 96.4% intensity at 1.95 mGy air s −1 for 3800 s) and during long‐term storage at 80 °C for 60 days. This work establishes a design paradigm that directly correlates radioluminescence kinetics with strong exciton confinement and hierarchical energy funneling, paving the way for next‐generation ultrabright scintillators.