Eu3+-activated Ca3La2(BO3)4 red phosphors: Concentration-quenching mechanism, thermal stability, and dual applications in WLEDs and anti-counterfeiting

A conventional high-temperature solid-state reaction was used to synthesize Eu 3+ -doped Ca 3 La 2 (BO 3 ) 4 red phosphors, aiming to overcome the low color rendering index and high correlated color temperature of WLEDs caused by insufficient red spectral components. The XRD patterns indicate that Eu 3+ incorporation does not produce detectable impurity phases, while ionic-radius and charge-balance considerations suggest that Eu 3+ preferentially occupies La 3+ sites. Under 393 nm near-ultraviolet excitation, the samples exhibit intense red emission peaking at 612 nm, attributed to the 5 D 0 → 7 F 2 transition. The optimal doping concentration is 1.3, and concentration quenching is governed by dipole-dipole interactions with a calculated critical distance of 7.19 Å. The internal quantum efficiency reaches 67.21%, and the fluorescence lifetime is 2.64 ms. Thermal stability evaluation shows that at 473 K, the emission intensity retains 70.95% of its room-temperature value, yielding an activation energy of 0.1757 eV. A neutral white LED device was fabricated by encapsulating the optimally synthesized phosphor together with commercial green- and blue-emitting phosphors onto a 365 nm chip, achieving a correlated color temperature of 4767 K and a color rendering index of 91.1. Additionally, anti-counterfeiting ink formulated from this phosphor shows bright red luminescence under UV excitation. Collectively, Ca 3 La 2 (BO 3 ) 4 : Eu 3+ serves as an efficient red phosphor with excellent thermal stability, making it highly promising for solid-state lighting and anti-counterfeiting applications.