Red/near-infrared emitting phosphors based on Bi³⁺ ions: recent advances, materials design, and applications

In recent years, Bi³⁺-doped luminescent materials have attracted widespread attention due to their diverse electronic transition types and tunable emission properties. While most Bi³⁺-doped phosphors primarily emit in the ultraviolet to yellow spectral region, recent studies have successfully achieved efficient broadband red and near-infrared (NIR) emission through strategies such as crystal field/defect engineering and energy transfer, thereby breaking the traditional limitations of the emission spectrum. This review systematically summarizes the latest progress in Bi³⁺-based red/NIR phosphors, with emphasis on the luminescence mechanism, material design strategy, performance influencing factors, and application prospects in optical thermometry, plant cultivation lighting, and information encryption. Finally, we discuss current challenges and future research directions, aiming to provide theoretical guidance and insights for the development of novel high-performance Bi³⁺-doped long-wavelength phosphors.