Enhancement of upconversion luminescence of Al₂O₃: Er³⁺, Yb³⁺ thin films by small assemblies of Au nanorods

Abstract

Enhancement of upconversion luminescence by small assemblies of Au nanorods such as dimers, trimers, tetramers, etc, is studied by comparing upconversion images with electron microscope images. We show that small assemblies starting from dimers can enhance the upconversion luminescence, while isolated Au nanorods cannot. The analysis of the data reveals that the gaps between nanorods act as hot spots for the enhancement of upcnversion luminescence.