Research progress on Fe³⁺-activated near-infrared phosphor

Fe³⁺-activated near-infrared (NIR) luminescent materials have attracted widespread attention due to their tunable emission wavelength and extensive applications in various fields such as plant growth, food analysis, biomedical imaging, and night vision. Many excellent NIR materials have been developed by introducing non-toxic and environmentally friendly Fe³⁺ ions into different inorganic hosts. This article elucidates the luminescent properties of Fe³⁺ ions by combining the Tanabe–Sugano energy level diagram and the configuration coordinate model. The latest research progress on Fe³⁺-doped NIR luminescent materials is outlined, summarizing the luminescent characteristics of various Fe³⁺-doped materials, including emission wavelength, emission bandwidth, quantum efficiency, and thermal stability. Particularly, a detailed summary and analysis of the application areas of Fe³⁺-doped NIR luminescent materials are provided. Finally, the future prospects and challenges faced by Fe³⁺-doped NIR luminescent materials are presented. This review contributes to a deeper understanding of the luminescence mechanism of Fe³⁺ and the research progress of iron ion-doped luminescent materials, aiming to develop advanced Fe³⁺-activated NIR luminescent materials with enhanced performance and explore new application fields.