Influence of Li+ doping on the luminescence performance of green nano-phosphor CaWO4:Tb3+ as a sweat pores fingerprint and cheiloscopy sensor

Abstract

We have developed green phosphors nanoparticles CaWO4:Tb3+ co-doped Li+using facial co-precipitation process, which can accurately control the composition, nanostructure, and surface condition of luminescent NPs. The structures and morphology of the developed nanophosphores were characterized by X-ray diffraction (XRD), high-resolution transmission electron microscope (TEM), and energy dispersive X-ray (EDX) methods. Their optical properties were performed by UV–visible, fluorescence, and FTIR methods. The phosphors exhibit green emission peak at 540 nm upon excitation at 255 nm corresponding to 5D0 → 7F2 transitions characteristic of Tb3+ with excellent CIE coordinates (x = 0.282 and y = 0.600), which are in close agreement with the regular NTSC values (xd = 0.290, yd = 0.600). This phosphor powder exhibited a flexible fluorescent mark for the detection of level 1–3 details with high contrast of latent fingerprint (LFP) and I-type V of Cheiloscopy for individual identification in forensic science. Our results reveal that the developed nanophosphors (CaWO4: Tb3+, Li+) has potential practical application for latent fingerprint identifications on different types of non-pores and pores surfaces common to forensic cases to solve crimes and as a valuable tool for law enforcement. Also, the novel nano-phosphor has significant ability to minimise the background fluorescence interference irrespective of the surface type used.