Yb ³⁺ ‐Doped Lead‐Free Halide Perovskite as High‐Performance Near‐Infrared Scintillation Material for X‐Ray Imaging

ABSTRACT With the continuous improvement of the efficiency of photodetectors in the near‐infrared (NIR) region in recent years, NIR scintillator materials have attracted more and more attention from researchers. Current scintillator materials either emit in the visible region or have low light yield in the NIR region. Herein, we describe efficient NIR scintillation by doping Yb 3+ in lead‐free halide double perovskites (DP) Cs 2 NaYCl 6 . Its light yield reaches 93295 photons·MeV −1 , and the detection limit is as low as 4.2 µGy air ·s −1 upon radiation with 20 keV X‐ray. Moreover, it exhibits great irradiation hardness, maintaining 96% of its initial scintillation intensity after exposure to an X‐ray dose of 6.66 Gy air . A flexible scintillator film Cs 2 NaYCl 6 : Yb 3+ @PDMS with an area of 100 cm 2 is prepared by combining the material with PDMS as a carrier and successfully applied to X‐ray imaging. The spatial resolution of the scintillation screen is determined to be 10 lp·mm −1 using line‐pair phantoms and modulation transfer function (MTF). This finding reveals that lead‐free halide perovskites are attractive functional materials suitable for matrices of NIR scintillation materials.