Synthesis and upconversion emission of NaYF4:Er/TiO2/Ag core-shell nanocomposites

The synthesis of core/shell NaYF4:Er/TiO2/Ag (NETA)hybrid nanostructure was prepared by the thermal decomposition process which involves Polyvinylpyrrolidone for dissolving precursors to form core NaYF4:Er. However, TiO2 and silver nanoparticles (AgNPs) shell were deposited on the core nanocrystal using Tetraethyl orthotitanate (TEOT) and AgNO3 to obtain core-shell structure. The Uv-Vis-Nir absorption spectra for identification surface plamon band and the core-shell nano structural analysis were studied. Upon 808 nm laser diode excitation to NETA samples exhibit mainly green upconversion enhancement which remarkably two times and lesser red emission intensity has been marked. Through the interaction of Er3+ with SPR of AgNPs leads to enhance green band and it may be proven potential material for application in bioimaging. The presences of AgNP shell on nanocrystal of nanocomposite and upconversion mechanism related to enhancement were discussed.