SPR studies in PVA composite films of SiO2@NaYF4:Er3+/Yb3+ UCNPs via AuNPs concentration variation and their temperature sensing applications

The composite film of mesoporous silica coated NaYF4:Er3+/Yb3+ upconversion nanoparticles and gold nanoparticles (AuNPs) in Poly vinyl alcohol (PVA) medium were prepared. The effect of the concentrations of AuNPs with 0 µl, 50 µl, 100 µl and 150 µl on the structure and upconversion luminescence intensity were studied. The phenomenon of enhancement in upconversion luminescence intensity due to AuNPs were explained via surface plasmon resonance (SPR) phenomenon. Apart from this the XRD, FE-SEM and AFM studies were done for estimation of structure and surface morphology etc. The impurities were estimated through FTIR analysis. The optical properties of these polymer composite films were studied via UV–vis absorption spectra and upconversion luminescence spectra analysis. A low temperature sensing ability of these films have been demonstrated for the suitability of these films in bio-medical applications.