The single‐band red upconversion emission of Er3+ in YbOCl layered structure

The single-band red upconversion (UC) emission of lanthanide-doped materials have attracted attention due to its great potential for versatile applications. In this work, YbOCl: x Er 3+ with super pure red UC emission had been successfully synthesized by conventional high temperature solid-state reaction. X-ray powder diffraction (XRD) confirmed the rhombohedral structure with space group R -3 m (166). Scanning electron microscopy (SEM) exhibited agglomeration morphology of smooth sheets with nanometer thickness. The UC emission spectra of YbOCl:Er 3+ manifested intense red emission and much lower green emission when pumped by 980 nm diode laser. The dominating red emission peaking at 670 nm was assigned to the electron transition 4 F 9/2 → 4 I 15/2 . The green emission at 521 nm and 547 nm were corresponding to 2 H 11/2 → 4 I 15/2 and 4 S 3/2 → 4 I 15/2 transition of Er 3+ , respectively. The CIE chromaticity coordinates showed the color of samples lain in red region and the purity of red emission could be tuned by the concentration of Er 3+ . The UC luminescence mechanism was proposed based on the relationship of UC intensity versus pump power density and their lifetime. Our research provided a new thought for realizing single-band red emission without any further modification.