Ultra-broadband shortwave infrared emission under blue light excitation of Cr 3+ /Ni 2+ co-doped Y 3 Al 3 MgSiO 12 garnet phosphor through effective energy transfer and its application

Short-wave infrared (SWIR) phosphor-converted light-emitting diodes (pc-LEDs) are promising for biomedical and nondestructive applications. Still, their progress is constrained by the lack of efficient, ultra-broadband phosphors excitable by low-cost blue LEDs. Cr3+-activated materials exhibit strong blue light excitation, but their emission is primarily confined to the NIR-I region. In contrast, Ni2+ has the potential to achieve SWIR emission, yet suffers from weak absorption in the blue-light region. In this study, Y3Al3MgSiO12: Ni2+ and Y3Al3MgSiO12: Cr3+-Ni2+ phosphors were synthesized. Compared to previous reports, the Y3Al3MgSiO12: Cr3+-Ni2+ phosphor in this study achieved three significant advancements. (1) Efficient energy transfer from Cr3+ to Ni2+ was achieved (η=91.6%), resulting in a 10.45-fold enhancement of SWIR emission intensity upon 438 nm blue-light excitation, and the optimal excitation wavelength was shifted into the blue-light region. (2) Ultra-broadband continuous emission spanning the NIR-I to NIR-III regions, with an exceptionally wide FWHM (185+311 nm) was achieved in this phosphor. (3) Remarkably high thermal stability was achieved for the NIR-II-III emission, in a region where strong electron-phonon coupling and poor thermal stability are typically observed. The underlying mechanism was elucidated through analysis of the crystal structure rigidity and the Huang-Rhys factor (S). A SWIR pc-LED device was further fabricated by integrating the phosphor with a 450 nm blue LED chip, confirming its application potential in covert information recognition and nondestructive detection scenarios. This study not only introduces a broadband SWIR-emitting material system excitable by blue light but also provides a novel strategy for developing efficient and thermally stable SWIR phosphors.