One-Dimensional All-Inorganic K2CuBr3 with Violet Emission as Efficient X-ray Scintillators

Lead halide perovskites have shown great X-ray scintillation properties. One big challenge is to find nontoxic replacements for practical applications. Moreover, the scintillator should contain less intrinsic radioactivity as possible to suppress the constant background signal. Here, we report K2CuBr3 with ultralow intrinsic radioactivity. The abundance of radioactive isotope K-40 is 0.0118%, while Cu and Br do not contain stable radioactive isotopes. Thanks to the one-dimensional crystal structure and strong electron-phonon coupling, K2CuBr3 exhibits strong carrier confinement and high photoluminescence quantum yield (86.98%) for the violet emission (peak, 391 nm). Such a high PLQY value is among the highest for all kinds of violet emitters. For X-ray scintillation applications, we evaluate the light yield to be 23,806 photons per MeV, and the detection limit is 132.8 nGy(air) s(-1).