Ionothermal synthesis of a stable three-dimensional [Cu4I4] cluster scintillator with near-unity quantum efficiency and weak thermal quenching

Abstract

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 clusters 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 luminescence intensity at 110 °C can still maintain 90% of its room temperature value. After being placed in air for 100 days, the luminescence intensity retains 88.34% of its initial one. The compound demonstrates a strong X-ray response, achieving an effective light yield of 48 538 photons per MeV and a detection limit of 30.68 nGy_air s⁻¹, far below the medical diagnostic dose of 5.5 μGy_air s⁻¹. The successful development of this compound provides inspiration for green, non-toxic, and efficient detection applications.