Ultra-broadband shortwave infrared emission under blue light excitation of a Cr3+/Ni2+ co-doped Y3Al3MgSiO12 garnet phosphor through effective energy transfer and its applications

Abstract

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 to 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.