Self assembly of three-dimensional Lu2O3:Eu3+ inverse opal photonic crystals, their modified emissions and dual-functional refractive index sensing

Abstract

In this study, Lu₂O₃:Eu³⁺ inverse-opal-photonic crystals (IOPCs) with controllable lattice constants were fabricated using a polymethylmethacrylate (PMMA) template. The modification effect of PC on the ⁵D₀–⁷F_J and ⁵D₁–⁷F_J (J = 1–6) transitions were systemically studied by emission spectra, luminescent dynamics and the temperature-dependence. It is significant to observe that the increase of ⁵D₀–⁷F_J radiative lifetime for Eu³⁺ ions (30%) in contrast to the reference sample was mainly due to modulation of the effective refractive index, rather than the density of optical states. The spontaneous decay rate in ⁵D₁ increased linearly with the decreasing lattice constants, which was due to the change in ⁵D₁–⁵D₀ nonradiative relaxation of the IOPC samples. The temperature quenching of Eu³⁺ ions in the IOPCs could be suppressed considerably more than the reference. On this basis, dual functional refractive index detection with infiltrated solutions was realized by monitoring the variation in the photonic stop band (PSB) and the lifetime of ⁵D₀–⁷F₂ transition of the Lu₂O₃:Eu³⁺ IOPCs. This work shows that the Lu₂O₃:Eu³⁺ IOPCs present highly modified photoluminescence properties and are promising candidates for dual-functional refractive index sensing application.