Compositional tailoring via source doping for intense NIR photoluminescence in solution-processed Er ³⁺ :As ₂ Se ₃ thin films

Rare-earth-doped chalcogenide films, as key materials for flexible optoelectronic integrated devices, have shown considerable potential in optical communications, precision metrology, and optical sensing. Herein, we address a persistent challenge in the dissolution of selenide glasses by developing an optimized ethylenediamine-based solvent system that enables exceptional solubility of As₂Se₃-up to 0.78 g/mL-in organic amine solvents. Leveraging this achievement, we engineered a highly uniform and reproducible spin-coating process for film fabrication. Through precise control of annealing temperature and Er³⁺ doping concentration, we demonstrate, for the first time, intense near-infrared (NIR) photoluminescence (PL) at 1.5 µm from Er³⁺-doped As₂Se₃ films, with optimal performance achieved at 3 mol% Er³⁺. Additionally, a source solution doping strategy was employed to tailor film composition, revealing the critical impact of introducing Se or As into the As₂Se₃ precursor solutions on the luminescence efficiency of Er³⁺-doped films. This work provides a robust and scalable approach for the fabrication of high-performance chalcogenide luminescent films, advancing their application in next-generation photonic devices.