Enhanced quantum efficiency and thermal stability by crystal-field engineering in a Y(Ga,Al)3(BO3)4:Cr3+,Yb3+ phosphor for diverse short-wave infrared applications

Abstract

The increasing need for night vision surveillance and medical imaging applications has expedited the progress of near-infrared (NIR) light sources, which require efficient broadband NIR luminescent materials. However, developing efficient broadband NIR luminescent materials is an ongoing and difficult task. Herein, we report a novel efficient NIR phosphor Y(Ga,Al)₃(BO₃)₄:Cr³⁺. By optimizing the Ga/Al ratio through crystal field engineering to modulate the crystal field around Cr³⁺ ions, a novel highly efficient YGa_1.8Al_1.2(BO₃)₄:0.08Cr³⁺ phosphor was obtained, exhibiting a wide NIR emission spanning from 650 to 1000 nm with a full width at half maximum (FWHM) of 115 nm. Additionally, it showed a high internal quantum efficiency (IQE) of 88% and remarkable temperature stability (I_373K/298K = 95%). When codoped with Yb³⁺ ions, the YGa_1.8Al_1.2(BO₃)₄:Cr³⁺,Yb³⁺ phosphor emits intense NIR light in the range of 900–1100 nm, and the luminescence performance is further improved. A NIR pc-LED achieves a high output power of 62.5 mW and a 15.8% efficiency at 125 mA. Furthermore, we confirmed the prospective multifunctional applications in non-destructive medical diagnostics, information encryption, and night vision illumination.