Researchers at the Institute of Rare Earth Luminescent Materials and Devices, School of Rare Earth, Jiangxi University of Science and Technology (JXUST), have published a paper in Advanced Functional Materials, a top-tier Q1 journal in materials science with an impact factor of 19.9. The paper is titled “Balanced Cr3+ and RE3+ Luminescence in a Novel Non-Concentration-Quenching Cs2RbCrF6: High-Efficiency Wide-Coverage NIR Phosphors Toward Solvent Extraction Monitoring.” The first author is Pan Xixiang, a PhD student enrolled in 2023, and the corresponding authors are Professors Liu Songbin and Ye Xinyu. JXUST is the sole corresponding institution.
Near-infrared (NIR) light sources with broad spectral coverage and high luminous efficiency are promising for spectral detection, bioimaging and anti-counterfeiting. However, conventional Cr3+-doped NIR phosphors emit mainly in the first NIR window (NIR-I). Extending emission into the second NIR window (NIR-II) through rare-earth co-doping often weakens Cr3+ emission, making broad-spectrum luminescence a key challenge.
To address this, the team designed the host structure and prepared double-perovskite Cs2RbScF6:Cr3+ NIR phosphors using a solvothermal method without added hydrofluoric acid. The large spacing between luminescent ions prevented concentration quenching. The fully Cr-substituted Cs2RbCrF6 phosphor showed the strongest emission, with internal and external quantum efficiencies of 84.2% and 32.1%, respectively, and a broad NIR emission peak at 775 nm with a full width at half maximum of about 118 nm. The team then introduced Yb3+, Nd3+ and Er3+ into Cs2RbCrF6. The high-content Cr3+ centers effectively sensitized the rare-earth ions, enhancing their characteristic emission while maintaining strong Cr3+ broadband emission. This balanced Cr3+ and RE3+ emission and produced efficient, wide-coverage NIR luminescence from 650 to 1600 nm, with an internal quantum efficiency of 74.1%. The researchers also combined the phosphor with a blue LED chip to build a NIR phosphor-converted LED (pc-LED) device and demonstrated its potential for monitoring rare-earth solvent extraction. The device could quantitatively detect Nd3+ concentrations in aqueous and organic phases and identify 1 vol% water entrainment in the organic phase. The work turns high Cr content from a quenching source into a sensitization source, offering a new design logic for efficient wide-coverage NIR materials and process-analysis light sources.
The study provides a new approach for designing efficient wide-coverage NIR luminescent materials and a reference for developing optical monitoring technology for rare-earth solvent extraction. The work was supported by the National Natural Science Foundation of China, the Jiangxi Provincial Department of Science and Technology and JXUST.
The Institute of Rare Earth Luminescent Materials and Devices is an interdisciplinary research body spanning materials, metallurgy and chemistry. It relies on national platforms including the National Rare Earth Functional Materials Innovation Center, the National Engineering Research Center for Efficient Development and Utilization of Ion-Adsorbed Rare Earth Resources, and the Ministry of Education Key Laboratory for the Development and Application of Ion-Adsorbed Rare Earth Resources. In recent years, it has undertaken more than 50 national and provincial projects and over 10 industry-funded projects, with total funding of nearly RMB 20 million. It has won more than 10 provincial and ministerial science and technology awards, published over 150 SCI papers, including in Materials Today, and holds more than 20 authorized invention patents. Some results are internationally leading and have been applied.
Original link: https://doi.org/10.1002/adfm.202679129
