Modelling of the luminescent properties of nanophosphor coatings with different porosity

Abstract

Coatings of Y₂O₃:Eu nanophosphor with the effective refractive index of 1.02 were obtained by flame aerosol deposition (FAD). High-pressure cold compaction decreased the layer porosity from 97.3 to 40 vol % and brought about dramatic changes in the photoluminescent performance. Modelling of interdependence between the quantum yield, decay time of luminescence, and porosity of the nanophosphor films required a few basic simplifying assumptions. We confirmed that the properties of porous nanostructured coatings are most appropriately described by the nanocrystal cavity model of the radiative decay. All known effective medium equations resulted in seemingly underestimated values of the effective refractive index. While the best fit was obtained with the linear permittivity mixing rule, the influence of further effects, previously not accounted for, could not be excluded. We discuss the peculiarities in optical response of nanophopshors and suggest the directions for future research.