Short Lifetime Radical Metal Cluster Scintillator

Metal clusters, an emerging class of scintillator materials, have attracted much attention owing to their inherently high X-ray absorption, mild synthesis conditions, low toxicity, strong luminescence, and large Stokes shift. However, the decay lifetime of metal clusters is usually on the order of microseconds, which is unfavorable for safety inspection, nondestructive testing, and medical imaging. Here, the open-shell luminescent radical ligand was used to construct the first radical cluster scintillator Cu₂I₂(L)₄. The spin-allowed doublet emission of Cu₂I₂(L)₄ theoretically enabled 100% exciton utilization and exhibited a short radiation decay lifetime on the nanosecond scale. Cu₂I₂(L)₄ can be fabricated into a flexible scintillator screen for X-ray imaging, achieving a high resolution of 30.7 LP mm^-1. More importantly, the Cu₂I₂(L)₄ scintillator screen has no residual images during X-ray imaging. This work reports the first luminescent metal cluster with a radical ligand and presents a new strategy for constructing short lifetime X-ray scintillators.