Plasmon-enhanced upconversion luminescence with the hybrid structure of semiconductor-insulator-semiconductor

High-quality hexagonal NaYF4:Er/Yb particles and monodisperse copper(I) sulfide nanoparticles (NPs) were obtained with the solvothermal method and the hot-injection method, respectively. The hybrid structure of semiconductor-insulator-semiconductor (SIS) was constructed for upconversion luminescence (UCL). The results showed that compared with that of NaYF4:Er/Yb-SiO2 particles, the luminous intensity of SIS was promoted by 12.5 folds, and the quantum yield of SIS can reach to 0.89%. Furthermore, the optical field distribution in the vicinity of hybrid structure of SIS was numerically simulated based on the finite-time domain-difference method (FDTD). The UCL enhancement of the SIS originates from the amplified optical field, which was attributed to the localized surface plasmon resonance (LSPR) effect of copper(I) sulfide NPs and the local effect of the copper(I) sulfide film on the excited light.