fig1

Figure 1. (A and B) UV-vis absorption and PL spectra of Yb³⁺:CsPbCl₃ NCs before and after CdCl₂ post-treatment; (C and D) XRD patterns of Yb³⁺:CsPbCl₃ NCs treated with different amounts of CdCl₂, together with an enlarged view around the (200) diffraction peak at approximately 31.8°. The standard XRD pattern (PDF#73-0692) of cubic CsPbCl₃ is shown at the bottom as a reference; (E-H) TEM images of Yb³⁺-doped CsPbCl₃ NCs before and after CdCl₂ post-treatment (scale bar: 20 nm), along with the corresponding high-resolution TEM images (scale bar: 5 nm); (I) Schematic illustration of the lattice of Yb³⁺-doped CsPbCl₃ NCs before and after CdCl₂ post-treatment; (J-N) High-resolution XPS spectra of untreated (blue) and CdCl₂ post-treated (green) Yb³⁺:CsPbCl₃ NCs, including Cs 3d, Pb 4f, Cl 2p, Yb 4d, and Cd 3d regions. XRD: X-ray diffraction; NCs: nanocrystals; TEM: transmission electron microscopy; XPS: X-ray photoelectron spectroscopy; PLQY: photoluminescence quantum yield; UV-vis: ultraviolet-visible; PL: photoluminescence.