Interactions in Rare Earth Doped Nanoparticles: A Multi-Transition, Concentration, and Excitation Path Analysis

Understanding and modeling energy transfer mechanisms in rare-earth-doped nanomaterials is essential for advancing luminescent technologies used in bioimaging, optical thermometry, and solid-state lasers. In this work, we investigate the photoluminescence dynamics of Yb3+ and Er3+ ions in Y2O3 nanoparticles over a wide concentration range (0.5-17%), using both direct and upconversion excitation. Luminescence decays of green, red, and near-infrared transitions were measured and analyzed using a rate-equation model incorporating radiative and non-radiative processes, energy transfer mechanisms, and defect-related quenching. The model successfully reproduces experimental trends across most concentrations and excitation paths. This work provides a reliable and predictive framework for modeling energy transfer in rare-earth doped materials and offers valuable insights for optimizing photoluminescent properties in nanostructured systems.