Lanthanide doping enabled multimodal luminescence in layered lead-free double perovskite Cs4MnBi2Cl12

Abstract

The incorporation of lanthanide ions (Ln³⁺) has been shown to be an effective strategy to tune the luminescence properties in lead-free halide double perovskites. However, most Ln³⁺-doped double perovskites exhibit a low luminescence efficiency and a high excitation energy and/or require doping with multiple ions which result in complex compositions. Herein, we demonstrate that the Ln³⁺ doping (Ln = Yb, Er, Nd) in the layered double perovskite Cs₄MnBi₂Cl₁₂ enables multimodal luminescence, that is, the orange-red emission from the d–d transition of Mn²⁺, the efficient ultraviolet light excited near-infrared (NIR) emissions of Ln³⁺ and the upconversion emissions in both Yb- and Yb/Er-doped systems. In addition, the NIR emissions of Ln³⁺ can also be excited by blue and green light benefiting from the energy transfer from Mn²⁺ to Ln³⁺. Finally, taking advantage of the multimodal luminescence in the Ln³⁺-doped Cs₄MnBi₂Cl₁₂ phosphor, a preliminary anti-counterfeiting application is demonstrated. We highlight that the particular chemical composition (comprising Bi³⁺ and Mn²⁺) and the sandwich-type Bi–Mn–Bi layered crystal structure facilitate the light absorption and the energy transfer from Bi³⁺ to Ln³⁺ and Mn²⁺ to Ln³⁺, demonstrating the importance of the rational selection and design of double perovskite host materials for Ln³⁺ doping.