Efficient short-wave NIR emission induced by energy transfer from Cr3+ clusters to Ni2+ in LiAl5O8:Cr3+,Ni2+ phosphor-in-glass for spectroscopy applications

Abstract

To achieve efficient short-wave infrared (SWIR) light sources, a series of LiAl₅O₈:Cr³⁺,Ni²⁺ phosphors were synthesized, demonstrating excellent internal quantum efficiency (IQE = 94.56%) and thermal stability (I_423K/I_293K = 67.90%). Here, a novel energy transfer (ET) pathway is proposed, revealing the efficient ET mechanism between Cr³⁺ clusters and Ni²⁺. The ET mechanism significantly enhances the emission intensity by approximately 24.60 times, while gradually shifting the optimal excitation wavelength from the ultraviolet region (367 nm) to the blue region (420 nm), effectively addressing the issue of weak blue light absorption. This underscores its potential for application in high-efficiency SWIR LEDs. Moreover, to avoid severe reabsorption of emission in traditional phosphor-converted light-emitting diodes (pc-LEDs), LiAl₅O₈:Cr³⁺,Ni²⁺ phosphor-in-glass (PiG) was utilized. Compared to conventional pc-LED packaging, PiG pc-LED exhibits a more stable spectral distribution and better thermal stability of luminescence at varying driving currents. This study not only presents a novel approach to enhance the luminescence performance of SWIR phosphors, but also demonstrates the promising application prospects of efficient phosphors in PiG pc-LEDs.