Preparation and photoluminescence of high-monochromaticity green-emitting Ca9Tb(PO4)5(SiO4)F2:Ce3+ phosphor with high quantum efficiency and excellent thermal stability for WLEDs application

In this study, a novel green-emitting fluorapatite phosphor Ca 9 Tb(PO 4 ) 5 (SiO 4 )F 2 :Ce 3+ (CTPSF:Ce 3+ ), which features excellent luminous efficiency and thermal stability, was first designed and prepared. High-concentration doping of Tb 3+ enables efficient green emission. Moreover, photoluminescence (PL) spectra and diffuse reflectance spectra reveal that the introduction of Ce 3+ extends the excitation spectrum to the range spanning 200 nm–380 nm, with a significant improvement in efficiency, which stem from the Ce 3+ → Tb 3+ energy transfer process. The introduction of Ce 3+ boosts the photoluminescence intensity of CTPSF by 2.315-fold, delivering a great internal quantum efficiency (IQE) of 73.95 % and an external quantum efficiency (EQE) of 57.86 %. Additionally, the thermal stability improved from retaining 66.3 % of the original intensity at 150 °C to 83.6 % retention of its original intensity at 150 °C. Finally, White-light-emitting diode (WLED) devices were fabricated by employing BaMgAl 10 O 17 :Eu 2+ (blue), CaAlSiN 3 :Eu 2+ (red), and the synthesized CTPSF:Ce 3+ (green) phosphors. Upon applying a forward bias current of 60 mA, the WLED device displayed a high color rendering index (Ra) of 92.7 and a low correlated color temperature (CCT) of 3973 K, validating the potential of this green-emitting phosphor for practical applications in WLED lighting systems.