Luminescence properties of LaNb2VO9:Eu3+ phosphors with efficient UV excitation bands for w-LEDs, plant cultivation LEDs, and latent fingerprint detection

Abstract

A novel red-emitting phosphor, LaNb₂VO₉:Eu³⁺, was successfully synthesized using the traditional solid-state reaction method. A comprehensive characterization was carried out, covering crystal structure analysis, X-ray diffraction (XRD), scanning electron microscopy (SEM), photoluminescence (PL) properties, decay time measurement, and luminous thermal stability assessment. Upon excitation at 301 nm, the LaNb₂VO₉:Eu³⁺ phosphor exhibited four distinct emission peaks, corresponding to transitions from the ⁵D₀ state to the ⁷Hn levels (where n = 1, 2, 3, and 4) of Eu³⁺. The most pronounced emission peak occurred at 618 nm, attributed to the ⁵D₀ to ⁷F₂ transition. The Judd-Ofelt parameters (Ω₂, Ω₄) for the Eu³⁺-doped LaNb₂VO₉ phosphors were determined from the emission spectra. It was determined that 30 mol% of Eu³⁺ was the most optimal doping concentration for La_1-xNb₂VO₉:xEu³⁺ phosphors. The optimal sample exhibited a high activation energy of 0.25 eV and exceptional luminous thermal stability. The fabricated red LED is capable of satisfying the photic requirements that are essential for the growth and development of plants. The chromaticity coordinate of the packaged white light-emitting diode (w-LED) was found to be (0.321, 0.322), which places it within the white light area. Additionally, the LaNb₂VO₉:30 mol%Eu³⁺ phosphor offers a lucid and comprehensive visualization of the I-III properties of fingerprints. These findings suggest that LaNb₂VO₉:Eu³⁺ phosphors have promising potential as red-light components for w-LEDs, plant cultivation LEDs and latent fingerprint detection applications.