Balanced Cr 3+ and RE 3+ Luminescence in a Novel Non‐Concentration‐Quenching Cs 2 RbCrF
Xixiang Pan, Songbin Liu, Shuyang Liu, Wanfang Zou, Yu Liao, Shuifu Liu, Fengli Yang, Chunpei Yan, Junjun Tan, Jiaqing Peng, Zhihua Xiong, Xinyu YeABSTRACT
Achieving wide‐coverage near‐infrared (NIR) luminescence spanning from NIR‐I to NIR‐II regions in Cr 3+ ‐sensitized rare‐earth‐ion (RE 3+ ) phosphor systems without sacrificing the Cr 3+ emission intensity remains a significant challenge. Herein, a novel double‐perovskite‐structured Cs 2 RbScF 6 host with large interionic separation was first discovered, which enables successful full substitution of Sc 3+ by Cr 3+ without concentration quenching. The resulting Cs 2 RbCrF 6 phosphor exhibits broadband NIR emission centered at 775 nm with a full width at half maximum of ∼118 nm, and high internal/external quantum efficiencies of 84.2%/32.1%. More importantly, this Cr‐rich host serves as an effective sensitizing platform for RE 3+ ions (i.e., Yb 3+ , Nd 3+ , Er 3+ ), extending the spectral coverage from 650 to 1600 nm via efficient Cr 3+ →RE 3+ energy transfer, while remarkably retaining substantial Cr 3+ emission intensity. This balanced coexistence of intense broadband Cr 3+ and multiple RE 3+ characteristic emissions enables a genuinely wide‐coverage NIR luminescence profile spanning 650–1600 nm. Finally, a prototype NIR phosphor‐converted LEDs device was fabricated and innovatively demonstrated practical utility for quantitatively monitoring various RE 3+ concentrations and detecting aqueous‐phase entrainment in the organic phase during solvent extraction. This work provides a rational design strategy for developing high‐efficiency wide‐coverage NIR phosphors and offers a new broadband NIR light source for real‐time monitoring of RE solvent extraction processes.