Upconversion luminescence mechanisms in Er³⁺ and Er³⁺/Yb³⁺ doped nanoparticles: dependence on phonon energies and concentrations

Abstract

Upconversion luminescence, a phenomenon where two or more lower-energy photons are converted into higher-energy emissions, holds significant potential for applications in several fields, including imaging, sensing, security inks, and photonics. Upconversion luminescence mechanisms in Erbium (Er³⁺) and Erbium-Ytterbium (Er³⁺ / Yb³⁺) doped nanoparticles have been investigated, focusing on the influence of dopant concentrations and phonon energies of the host lattice. Through systematic analysis and spectral characterization, we have elucidated how phonon-assisted energy transfers and multiphoton cooperative mechanisms dictate the observed luminescence behavior. Our findings provide valuable insights into tailoring the upconversion efficiency and emission spectra of doped nanoparticles for enhanced applications.