Afterglow Copper(I) Iodine Cluster Scintillator

Abstract

Copper(I) iodine clusters have drawn intense attention due to their advantageous photophysical properties, such as a high luminescence efficiency, large Stokes shift, and tunable luminescence lifetimes. In this work, a copper(I) iodine cluster (Cu₂I₂-CH₃CN) was synthesized, which exhibits unique afterglow emission, ultrahigh quantum yield (90.1 % in solid state) and aggregation-induced emission (AIE) behavior. It was found that thermally activated delayed fluorescence (TADF) and long-lifetime phosphorescence occur simultaneously in Cu₂I₂-CH₃CN. The unique photoluminescence properties of Cu₂I₂-CH₃CN were attributed to the large spin-orbit coupling (SOC) and long-term rigidity of the crystal. The high quantum efficiency, TADF characteristics, and heavy-atom composition of Cu₂I₂-CH₃CN endow it with excellent X-ray excited luminescence (XEL) properties, making it a promising X-ray scintillator. A flexible scintillator screen made of Cu₂I₂-CH₃CN was successfully fabricated and used for X-ray imaging with a spatial resolution of 23.6 LP mm^-1.