Plasmon-Enhanced Upconversion Luminescence on Vertically Aligned Gold Nanorod Monolayer Supercrystals

Upconversion nanophosphor is attracting world, wide interests-owing to its unique optical properties and great application potentials. However, it is still a great challenge to effectively improve the efficiency/strength of upconversion nanophosphor. Plasmonic modulation is a promising way to solve this bottleneck. In this work, we present a simple yet versatile concept on magnifying upconversion luminescence of NaYF4:Yb3+, Er3+ nanocrystals through local field manipulation of Surface plasmon. Gold nanorods were directionally assembled into a vertically aligned monolayer supercrystals over large areas. The FDTD simulation indicates that the electromagnetic field strength vertical bar E vertical bar(2) can be improved about 113 folds at the hot spots of monolayer supercrystals. After optimization, on the surface of the vertically aligned monolayer supercrystals, the overall up-conversion luminescence intensity of NaYF4:Yb3+, Er3+ under 980 nm excitation was improved more than 35 fold.