Ultrathin scintillators enabled via rapidly growing large-area 2D lanthanide oxychloride doped with Eu3+/Tb3+ for X-ray imaging

Ultrathin scintillators are key components of high-spatial-resolution X-ray detectors in medical imaging, high-precision nondestructive inspection, and high-energy physics. Currently, the spatial resolution of X-ray imaging detector generally is enabled by high-light-yield scintillators with minimal optical scattering. However, suppressing optical scattering losses typically require the scintillation layers thinner than a few tens of micrometers, which is difficult to obtain through conventional top-down mechanical thinning. Here, a bottom-up method that rapidly growing inch-sized, Eu 3+ /Tb 3+ doped lanthanide oxychloride (LaOCl) films via chemical vapor deposition (CVD) is proposed to obtain large-area ultrathin scintillators. The doping Eu 3+ /Tb 3+ ions act as luminescent activators and provide strong red and green scintillation through efficient f-f intra-configurational transitions, which are shielded from the host lattice by the outer 5s 2 5p 6 electron shells, resulting in sharp emission lines and high quantum efficiency. The layered crystal structure of LaOCl further facilitates anisotropic growth, enabling precise control of film thickness from a few atomic layers up to the micrometer scale. The growing LaOCl:Eu 3+ film with thickness of approximately 30 μm shows a photoluminescence quantum yield (PLQY) of 99.3%, and demonstrating an ultralow X-ray dose-rate detection limit of 143.41 nGy s −1 , owing to efficient energy transfer from the LaOCl host to the activator ions. Furthermore, the growing LaOCl:Eu 3+ /Tb 3+ films exhibit excellent linear response and radiation hardness under X-ray exposure, retaining above 95% of their initial intensity after prolonged cyclic irradiation at 27.8 μGy s −1 for 24,000 s. These results demonstrate CVD-grown LaOCl:Ln films as a promising platform for high-resolution and low-dose X-ray imaging detection. An ultrathin scintillator film is fabricated via an unconventional bottom-up chemical vapor deposition–driven evaporation growth method. The oriented attachment and layer-by-layer stacking of LaOCl:Ln 3+ crystal nuclei enables the fabrication of centimeter-scale ultrathin films with controllable thickness. The doping Eu 3+ and Tb 3+ act as luminescent activators, generating intense red and green emissions through efficient 4f-4f intra-configurational transitions. Owing to the effective shielding of the outer 5s 2 5p 6 electron shells, these transitions exhibit sharp emission lines and exceptionally high quantum efficiency. For LaOCl:Eu 3+ films with a thickness of approximately 30 μm, the photoluminescence quantum yields achieves a near unit of 99.3%, demonstrating an ultralow X-ray detection limits of 143.41 nGy s −1 and outstanding radiation stability. Download: Download high-res image (333KB) Download: Download full-size image