Ultra‐Broad Emission Copper Halide Scintillator‐Based X‐Ray Imager

Lead-free metal-halide scintillators are gaining considerable attention as more eco-friendly and superior alternatives to their lead-based counterparts. However, novel broad-emission band scintillators like the state-of-the-art CsI: Tl scintillator, which can generate high signals due to its strong compatibility with the spectral responsivity of regular photodiode arrays, are still less investigated. Herein, a TPA₂Cu₂I₄ (TPACI) copper halide scintillator with a unique ultra-broad emission (FWHM > 240 nm) is developed, which shows universal compatibility with the peak response range of commercial photodetector. The optical properties characterization and mechanism analysis indicates that this ultra-broad spectrum can be attributed to the dual self-trapped exciton (STE) emission consisting of two emission bands. Benefiting from the large Stokes shift and ultra-broad emission band enabled by the dual STE, the self-absorption-free TPACI scintillator exhibits efficient white light emission with a high photoluminescence quantum yields of 94.27%, a high light yield of ≈40124 photons MeV^-1. Moreover, a prototype of a TPACI scintillator-based X-ray imager is assembled for inspecting the internal structures of biological and electronic devices, which demonstrated a high resolution of 5.5 lp mm^-1 at modulation transfer function = 0.2. These findings provide insights into the design of efficient, broad-emission scintillators for high-resolution X-ray imaging.