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 ⁴⁰K 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.

中文翻译：

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一维全无机K ₂ CuBr ₃与紫光发射作为高效X射线闪烁体

卤化铅钙钛矿具有出色的X射线闪烁特性。一个巨大的挑战是找到无毒的替代品用于实际应用。此外，闪烁体应包含较少的固有放射性，以抑制恒定的背景信号。在这里，我们报道了具有超低本征放射性的K ₂ CuBr ₃。放射性同位素⁴⁰ K的丰度为0.0118％，而Cu和Br不包含稳定的放射性同位素。由于一维晶体结构和强的电子-声子耦合，K ₂ CuBr ₃对紫光发射（峰值，391 nm）表现出强的载流子限制和高的光致发光量子产率（86.98％）。如此高的PLQY值是所有紫色发射器中最高的。对于X射线闪烁应用，我们评估的光通量为每MeV 23806光子，检测极限为132.8 nGy _air s ^–1。