Sensitized near-infrared lanthanide emission in chalcogenide perovskites

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.