Ionothermal Synthesis of a Stable Three-Dimensional [Cu4I4] Cluster Scintillator with Near-Unity Quantum Efficiency and Weak Thermal Quenching

A facile and environmentally friendly ionothermal synthesis was employed to prepare a highly luminescent hybrid scintillator, Cu4I4(C6H14N2)2 (1, (C6H14N2)2 = 1,4-dimethylpiperazine). 1 features a 3-D structure of (Cu4I4) cubane cluster connected by 1,4-dimethylpiperazine. The optical properties of 1 under UV light and X-ray excitation were investigated. The results revealed that its excellent electronic transport properties enable a near-100% quantum yield. Moreover, its luminescent intensity at 110°C can still maintain 90% of its room temperature value. After being placed in air for 100 days, the luminescent intensity retains 88.34% of its initial one. The compound demonstrates a strong X-ray response, achieving an effective photon yield of 48538 photons/MeV and a detection limit of 30.68 nGy/s, far below the medical diagnostic dose of 5.5 μGy/s. The successful development of this compound provides inspiration for green, non-toxic, and efficient detection applications.