Zero-dimensional cuprous halide scintillator with ultra-high anti-water stability for X-ray imaging

Zero-dimensional (0D) cuprous organic–inorganic hybrid halides have emerged as a new kind of scintillator due to their high light yield and adjustable emission properties in the whole visible spectral range. However, their practical application in the radiation industry is seriously hindered by the instability of Cu^I ions under humid atmospheres and oxidizing environments. Herein, we designed a new Cu(I)-based halide of [CEOMTPP]₂Cu₄Br₆ (CEOMTPP = ethoxycarbonylmethyl(triphenyl) phosphonium cation) containing a discrete [Cu₄Br₆]²⁻ nanocluster, which displays strong broadband yellow light emission with near-unity photoluminescence quantum yield (PLQY) and large Stokes shift of 206 nm. Remarkably, [CEOMTPP]₂Cu₄Br₆ shows ultra-high anti-water and anti-oxidation stability with steady emitting performance in water for over one year and in an acid–base aqueous solution for one day. Benefiting from the near-unity PLQY, large Stokes shift and negligible self-absorption, [CEOMTPP]₂Cu₄Br₆ exhibits excellent scintillation properties with a high light yield of 69 500 phonon per meV and low detection limit of 113.0 nGy s⁻¹. Furthermore, a high spatial resolution of 14.5 lp mm⁻¹ is achieved in X-ray imaging based on a [CEOMTPP]₂Cu₄Br₆@EVA composite-assembled scintillation screen, demonstrating its potential application in medical photography. This research provides a fundamental structural engineering strategy to design highly efficient and stable low-dimensional Cu(I) halides for X-ray radiation application.