Effect of Rb⁺ co-doping on the optical properties in VIS and NIR emitting CsPbCl₃:Yb³⁺ perovskite powder

Inorganic halide perovskites have been the subject of intensive research for their unique properties. Most current research focuses on halide ion exchange to modify the luminescence band gap and optical features. They are obtained mainly in colloids or thin layers, resulting in small grains with a narrow distribution. This work investigates an alternative way of tuning the optical features of powdered micrometric halide perovskites by substituting monovalent cations. The structural and spectroscopic properties of a concentration series of CsPbCl₃:10%Yb³⁺,x%Rb⁺ (x = 5, 10, 20, 30, 40) prepared by the solid-state reaction method were analyzed. It is shown that doping the host with rubidium ions can strongly influence the quality of the crystal structure of the studied materials and their spectroscopic properties. Particularly, an increase in the concentration of Rb⁺ ions in the host leads to the appearance of structural defects of a different type, allowing the intensity of the emission bands of both the matrix and the optically active dopant to be modified.