Solvothermal synthesis of lanthanide-doped CaF2upconversion nanoparticles using liquid-solid-solution approach

Abstract

Abstract Upconversion nanoparticles (UCNPs) capable of emitting pure green, red, blue, and white emissions have grabbed a lot of attention for bioimaging, security printing, and optoelectronic devices. Ho3+/Yb3+, Er3+/Yb3+, Tm3+/Yb3+, and Er3+/Tm3+/Yb3+ double- and triple-doped CaF2 nanoparticles (NPs) were synthesized by the solvothermal method. The nanoparticleswere characterized by XRD, FTIR, HR-TEM, Raman, and photoluminescence spectroscopy. Under 980 nm, UCNPs emit red, green, blue, yellow, and white emissions by the appropriate doping of lanthanide ions.The CIE-1931 chromaticity study was carried out to determine the color coordinate and color purity of the UCNPs. The color purity of red, green, blue, and yellow emissions exceeds 90%, showing the excellent chromatic performance. The energy transfer mechanismin the sensitizer Yb3+ions withthe activators Ho3+, Er3+, and Tm3+ was successfully studied. Er3+/Yb3+ co-doped CaF2 UCNPs were used to study the potential scope in latent fingerprint detection and security applications.