Energy-Transfer-Enhanced Cr/Ni Co-doped Broadband Near-Infrared Phosphor for Fluorescence Thermometers and Near-Infrared Window Imaging.

Here, near-infrared broad dual-band emission phosphors were achieved through energy transfer between Cr and Ni ions in the β-GaO host. All samples co-doped with Cr and Ni exhibit dual-band emission covering 600-1700 nm under 430 nm excitation. Thanks to the doping of Cr ions, the emission intensity of GaO:Cr, Ni phosphors has increased by about 2.4 times and the internal quantum efficiency has increased by 83.2% compared to GaO:Ni phosphors. Meanwhile, when the fluorescence lifetime was monitored at 745 nm, an efficient energy transfer between Cr and Ni ions in the β-GaO host was verified. Due to the significant differences in the emission temperature-sensitive properties of Cr and Ni ions, a thermometer was designed utilizing fluorescence intensity ratio technology, achieving a maximum relative sensitivity of 5.26% K, which surpasses most optical temperature measurement phosphors. This suggests that GaO:Cr, Ni samples hold promise as potential candidates for optical thermometer materials. Additionally, the broadband near-infrared emission of the GaO:Cr, Ni sample has been investigated for potential applications in component analysis and night vision, demonstrating its versatility for multifunctional applications.