Improved broadband luminescence in Gd2GaSb1-xTaxO7:Cr3+,Yb3+ pyrochlore phosphors: Near-infrared spectroscopic applications and dual-mode optical thermometry

The growing demand for spectroscopic applications in the fields of night vision monitoring, non-destructive analysis and bioimaging has led to extensive research into near infrared (NIR) light sources. Thus, the design of high-performance broadband Cr3+-doped NIR phosphors is of urgent and critical importance. Herein, novel Gd2GaSb1-xTaxO7:Cr3+,Yb3+ NIR-emitting pyrochlore phosphors were successfully explored. Via partly substituting Sb5+ by Ta5+ and tuning Cr3+ amount, a significant enhancement, broadening and redshift of Cr3+ NIR luminescence are exhibited under the radiation of 460 nm light. Moreover, higher thermal stability and wider NIR luminescence are realized by the proper introduction of Yb3+. A satisfactory NIR output power of 46.51 mW @ 300 mA and photoelectric efficiency of 10.82 % @ 10 mA of the fabricated NIR phosphor-converted light-emitting diodes (NIR pc-LEDs) based on Gd1.96Ga0.97Sb0.9Ta0.1O7:3%Cr3+,4%Yb3+ phosphor enable the demonstration in night vision and bioimaging applications. Besides, superior dual-mode optical thermometry was successfully constructed on fluorescence intensity ratio (Cr3+/Yb3+) and fluorescence lifetime (4T2) of Cr3+ in Gd2GaSb1-xTaxO7:Cr3+,Yb3+. These results confirm that Gd2GaSb1-xTaxO7:Cr3+,Yb3+ can serve as inspiring luminescent converters employed in NIR pc-LEDs and non-contact temperature sensing.