Sensitized near-infrared lanthanide emission in chalcogenide perovskites

Abstract

Semiconductor materials capable of hosting luminescent lanthanide ions (Ln³⁺) and sensitize their emission are scarce. Halide perovskites are prime systems for this purpose, yet they often feature toxic elements (e.g., lead) in their composition and have reduced stability. The discovery of alternative semiconductors that feature host-to-Ln³⁺ energy transfer mechanisms – while being more stable and environmentally benign – would thus broaden the applicability of this class of luminescent materials. Herein, we report near-infrared (NIR) emitting phosphors made of BaZrS₃ chalcogenide perovskite doped with Ln³⁺ ions (Ln = Yb, Er, Nd). We chose BaZrS₃ because it features (i) crystallographic sites that can accommodate Ln³⁺ ions, (ii) high light absorption coefficient in the visible, and (iii) stability. The phosphors were prepared via sulfurization of Ln³⁺-doped BaZrO₃ microparticles obtained by a microwave-assisted procedure. The so-obtained Ln³⁺-doped BaZrS₃ display low-temperature NIR emission characteristic of each Ln³⁺ ion when exciting the matrix. Following photoluminescence studies on doped and undoped BaZrS₃ as a function of temperature, we propose an energy level scheme that explains the rich NIR photoluminescence displayed by these phosphors. The obtained results pave the way for the optimization of Ln³⁺-doped BaZrS₃ for optical applications and are expected to spur the study of other ternary chalcogenides sensitization of Ln³⁺ luminescence.