Ultrafast Scintillator Based on Zirconium‐Doped Cesium Zinc Chloride Single Crystals and Their Charge Carrier Dynamics

Scintillators have been widely used for high-energy radiation imaging. It is in great demand and challenge to develop scintillator materials with fast decay time, high scintillation light yield, and low detection limit for high-resolution imaging applications such as time-of-flight positron emission tomography. However, it is still a challenge to develop the ultrafast carrier dynamics to achieve 100% ultrafast decay time with high scintillation light yield. To meet the demand, a series of component-tunable Cs2ZnCl4: x%Zr single crystals as promising ultrafast scintillators is successfully developed. With 8% of Zr-dopant (Cs2ZnCl4: 8%Zr), the single crystal exhibits high light yield (28000 photons MeV−1) and low detection limit (51 nGy s−1) under X-ray excitation. Photo-induced transient absorption signals on sub-nanosecond and nanosecond scales ensure almost 100% fast decay time (≈3 ns) in nanoseconds under γ-ray excitation. In particular, the different radiative transition processes are achieved under ultraviolet and high-energy radiation due to the tunable carrier dynamics from the shallow trapped state to the self-trapped exciton (STE) state.