X-ray scintillation in lead-free double perovskite crystals

Metal halide perovskites have shown great performance for various applications, including solar cells, light emitting diodes, and radiation detectors, but they still suffer from the toxicity of lead and instability. Here we report the use of lanthanide series as trivalent metals to obtain low toxicity and highly stable double perovskites (Cs2NaLnCl6, Ln=Tb or Eu) with high scintillation light yield. The crystals exhibit typical f-f transitions of lanthanide cations, while Cs2NaTbCl6 exhibits strong green photoluminescence, and Cs2NaEuCl6 exhibits red photoluminescence. Under X-ray radiations, the light yield of Cs2NaTbCl6 reaches 46600 photons MeV−1, much higher than that of the commercially used (Lu,Y)2SiO5:Ce3+ crystals (LYSO, 28500 photons MeV−1), and previously reported lead-based perovskites (14000 photons MeV−1). As a new member of lead-free perovskites, lanthanide-based double perovskites open up a new route toward radiation detections and potential medical imaging.