A NASICON-type structure NaAlNb(PO4)3:Cr3+ phosphor with both high efficiency and thermal quenching resistance

NIR pc-LEDs develop rapidly due to its spectral tunability and compact design. However, NIR phosphors with both high efficiency and superior thermal quenching resistance are scarce. In this study, a novel NASICON-type structure phosphate NaAlNb(PO 4 ) 3 :Cr 3+ phosphor was synthesized successfully. The crystal structures and the luminescence behaviors were systematically investigated. The phosphor exhibits a broadband NIR emission from 700 to 1100 nm, centered at 808 nm and with a full-width at half maximum (FWHM) of 131 nm. Owing to the high structural rigidity (Θ D = 624.9 K) and wide optical bandgap (E g = 4.1 eV), NaAlNb(PO 4 ) 3 :Cr 3+ shows a high internal quantum efficiency (IQE) of 87% and excellent thermal quenching resistance (retaining 84.19% of its room-temperature intensity at 373 K). A NIR pc-LED was fabricated by combining the as-prepared phosphor with a 460 nm blue LED chip, achieving a high photoelectric conversion efficiency of 18.37% and a strong NIR output power of 50.19 mW at a driving current of 100 mA. All results indicate the NaAlNb(PO 4 ) 3 :Cr 3+ is a promising phosphor for NIR light practical applications.