UV emission quenching in silicon-coupled upconverting nanocomposites

This study reports significant quenching of ultraviolet (UV) emission from NaYF4:Yb3+,Tm3+ upconversion nanoparticles (UCNPs) by silicon nanoparticles (SiNPs). SiNP-UCNP nanocomposite was fabricated using two approaches: (i) a bottom-up thermal coprecipitation method in which SiNPs served as growth seeds for UCNPs, and (ii) a solid-state synthesis route. Both methods enabled effective interaction between SiNPs and UCNPs, as evidenced by marked changes in emission behavior. In particular, the UCNP emission bands at 344 nm, 360 nm, 449 nm, and 473 nm were significantly suppressed in the nanocomposite due to the high UV and blue light absorption of SiNPs. Transmission electron microscopy revealed the structural evolution of the nanoparticles, showing that the bottom-up approach yielded a more homogeneous distribution of UCNPs around SiNPs compared with the solid-state method. These results suggest that nanocomposites could become a potential drug delivery system for photodynamic therapy with reduced photodamage caused by ultraviolet radiation.