A novel broadband-excited LaNb2VO9:Sm3+ orange-red-emitting phosphor with zero-thermal-quenching behavior for WLEDs and personal identification

Novel orange-red-emitting LaNb2VO9 (LNV):xSm(3+) (x = 0-35 mol%) phosphors were successfully synthesized through the traditional high-temperature solid-state reaction method. The crystal structure, SEM images, particle size distribution, XRD spectra, optimal concentration, zero-thermal-quenching behaviors, and luminescent stability of the samples were exhaustively studied. In particular, the phosphors presented broadband excitation that consisted of O2--> V5+ and O2--> Sm3+ charge transfer bands (CTB). Under 308 nm excitation, LNV:5 mol%Sm3+ phosphor emitted orange-red light with high intensity at the wavelength of 598 nm due to the (4)G(5/2) -> H-6(7/2) transition of Sm3+ ions. The sample with the optimal doping concentration of 5 mol% exhibited zero-thermal -quenching. Furthermore, a white light-emitting diode (WLED) with the Commission Internationale de L'Eclairage (CIE) coordinate of (0.347, 0.348) and the superior color rendering index (CRI, Ra) of 90 was smoothly fabricated. With the LNV: 5 mol%Sm3+ phosphor, the level 1-3 structure of latent fingerprints (LFPs) and the detailed features of lip prints were clearly detected under ultraviolet irradiation. Ultimately, the phosphor effectively detected LFPs in various daily life circumstances. Consequently, the zero-thermal-quenching orange-red LNV:Sm3+ phosphors have several promising applications in WLEDs and personal identification.