Size-dependent luminescence kinetics of rare-earth Er3+ ions in Y2O3 nanospheres

The luminescence kinetics of Er ions in Y2O3:Er nanospheres with diameters of 75–270 nm has been studied. A pronounced decrease in the luminescence decay times for Er3+ ion transitions in the green-red visible range is observed with increasing diameter up to 270 nm, unlike near-infrared emission at ∼1.5 μm. This finding is attributed to the appearance of photonic modes accelerating spontaneous luminescence, which is confirmed by a model calculation of bound optical states in the studied nanospheres.