Realizing Ultrabroadband NIR-II Emission and Wide-Range Wavelength Tuning in Cr4+-activated ABO2 (A = Li, Na; B = Al, Ga) Phosphors

• Published in: Inorganic chemistry Vol. 63; no. 29; pp. 13738 - 13747
• Main Authors: Yang, Xiaowei, Zou, Yanfei, Hu, Chen, Su, Shikun, Wang, Zhenghang, Dong, Houhe, Teng, Wenying, Teng, Bing, Zhang, Bingtao, Zhong, Degao
• Format: Journal Article
• Language: English
• Published: American Chemical Society 22.07.2024
• ISSN: 0020-1669; 1520-510X; 1520-510X
• DOI: 10.1021/acs.inorgchem.4c02087

Cr4+-activated phosphors are important candidate materials for NIR-II light sources, but providing a suitable lattice coordination environment for Cr4+ and achieving long wavelength broadband emission remains a challenge. In this work, a series of Cr4+-activated ABO2 (A = Li, Na; B = Al, Ga) phosphors were successfully prepared. Due to the presence of only tetrahedral coordination structures available for Cr4+ to occupy in the matrix crystal ABO2, the valence state and luminescence stability of Cr4+ are effectively guaranteed. Through the cation substitution design of A-site (Na → Li) and B-site (Ga → Al), the [BO4] tetrahedron is distorted and expanded, which degrades the symmetry of the Cr4+ coordination crystal field. Consequently, the central wavelength of the Cr4+ emission peak is tuned from 1280 to 1430 nm, and the fwhm is significantly extended from 257 to 355 nm. Thebroadband NIR-II light sources constructed with LiAlO2: 0.03Cr4+ and NaGaO2: 0.03Cr4+ phosphors verify their important potential applications in nondestructive testing and biological imaging.