LSPR-mediated improved upconversion emission on randomly distributed gold nanoparticles array

Abstract

Herein, we report the plasmonic upconversion (UC) emission enhancement of Gd₂O₃:Er³⁺/Yb³⁺ thin films grown on randomly distributed gold nanoparticles (AuNPs) on glass. The AuNPs were prepared by thermal annealing a gold thin film on a glass substrate at 500 °C for 2 h. Gd₂O₃:Er³⁺/Yb³⁺ thin films were deposited on AuNPs using the pulsed laser deposition technique. The prepared plasmonic films exhibited stronger UC emission intensities in comparison to the reference Gd₂O₃:Er³⁺/Yb³⁺ thin film. This enhancement in UC intensity was assumed to be due to the strong optical field associated with the localized surface plasmon resonance (LSPR) and strong light scattering from AuNPs. A theoretical simulation based on a finite element method was performed to understand the nature of the optical field confined in AuNPs present in the Gd₂O₃:Er³⁺/Yb³⁺ thin film. This study is believed to be beneficial for several applications such as thin film-based infrared detectors and high efficiency photovoltaic devices.