Enhancement of NIR-to-visible Upconversion by Silver-Nanowire Thin Films.

摘要

NIR-to-visible upconversion luminescence of NaYF4:17% Yb 3+,3% Er3+ upconversion nanoparticles (UCNP) in a poly(methyl methylacrylate), PMMA, film was enhanced by an underlying silver-nanowire thin film. Silver-nanowires of 70 nm diameter and 4 mum length were synthesized by a solvothermal method and then spin-coated onto glass slides. A 110 nm thin film of the upconversion matrix was spin-coated onto the silver-nanowire thin film. The resulting samples were characterized by AFM, TEM, absorbance spectroscopy, steady state and time-resolved luminescence spectroscopy. Under 980 nm excitation, the UCNP PMMA/Ag-enhanced film showed much stronger upconversion luminescence than a simple UCNP PMMA film, with a factor of 2--4 times enhancement. The photoluminescence kinetics of the UCNP PMMA/Ag-enhanced and UCNP PMMA films confirm the surface plasmon effects of silver-nanowire thin films on the enhancement of upconversion emission of NaYF4:17% Yb3+,3% Er3+.