Unraveling Luminescent Energy Transfer Pathways: Futuristic Approach of Miniature Shortwave Infrared Light-Emitting Diode Design

Phosphor-converted shortwave infrared phosphor light-emitting diodes (pc-SWIR LEDs, 900-1700 nm) are promising next-generation portable light sources for spectroscopy, security, optical communication, and medical applications. A typical design strategy involves energy transfer from Cr3+ to Ni2+, and thus, energy transfer from Cr3+-Cr3+ pairs to Ni2+ ions is important but challenging. Here, we report a Sr1-xLaxAl5.92Cr0.08Ga6-xO19:xNi2+ (x = 0-0.09) series for the SWIR emissions range of 900-1600 nm due to an energy transfer from Cr3+ and Cr3+-Cr3+ pair to Ni2+. Short-range structural studies using electron paramagnetic resonance and magnetometry measurements reveal that Ni2+ ions likely exist as isolated Ni2+ ions and Cr3+-Ni2+ pairs rather than forming Ni2+-Ni2+ pairs. The fabricated prototype SWIR pc-LED delivers a radiant flux of 12.43 mW under a 350 mA driving current. This work provides insights into the codopant strategy for energy transfer and the design of promising next-generation SWIR phosphors.